Bio

Academic Appointments


Administrative Appointments


  • Member, Canary Center at Stanford for Cancer Early Detection (2009 - Present)
  • Member, Stanford Cancer Center (2007 - Present)
  • Member, Bio-X Program (2007 - Present)
  • Member, Molecular Imaging Program at Stanford (MIPS) (2007 - Present)

Honors & Awards


  • Best Basic Science Paper Published in 2009, Journal of Nuclear Medicine (2010)
  • New Investigator Award, Department of Defense (2009)
  • Young Investigator Award, Melanoma Research Alliance (2009)
  • IDEA Award, California Breast Cancer Research Program (2008)

Professional Education


  • B.S., Sichuan University, Chemistry (1994)
  • M.S., China Institute of Atomic Energy, Radiopharmaceutical Chemistry (1997)
  • Ph.D., University of Missouri-Columbia, Chemistry (2001)

Research & Scholarship

Current Research and Scholarly Interests


The overall objective of my laboratory is to develop novel molecular imaging probes and techniques for non-invasive detection of cancer and its metastasis at the earliest stage, so that cancer can be cured or transformed into a chronic, manageable disease. The techniques developed in my research will allow a close examination of the molecular, metabolic and physiological characteristics of cancers and their responses to therapy. In order to achieve this goal, my lab is aimed to identify novel cancer biomarkers with significant clinical relevance, develop new chemistry for probes preparation, and validate new strategies for probes high-throughput screening.

Teaching

2013-14 Courses


Publications

Journal Articles


  • Impact of a Multiple Mice Holder on Quantitation of High-Throughput MicroPET Imaging With and Without Ct Attenuation Correction. Molecular imaging and biology Habte, F., Ren, G., Doyle, T. C., Liu, H., Cheng, Z., Paik, D. S. 2013; 15 (5): 569-575

    Abstract

    PURPOSE: The aim of this study is to evaluate the impact of scanning multiple mice simultaneously on image quantitation, relative to single mouse scans on both a micro-positron emission tomography/computed tomography (microPET/CT) scanner (which utilizes CT-based attenuation correction to the PET reconstruction) and a dedicated microPET scanner using an inexpensive mouse holder "hotel." METHODS: We developed a simple mouse holder made from common laboratory items that allows scanning multiple mice simultaneously. It is also compatible with different imaging modalities to allow multiple mice and multi-modality imaging. For this study, we used a radiotracer ((64)Cu-GB170) with a relatively long half-life (12.7h), selected to allow scanning at times after tracer uptake reaches steady state. This also reduces the effect of decay between sequential imaging studies, although the standard decay corrections were performed. The imaging was also performed using a common tracer, 2-deoxy-2-[(18) F]fluoro-D-glucose (FDG), although the faster decay and faster pharmacokinetics of FDG may introduce greater biological variations due to differences in injection-to-scan timing. We first scanned cylindrical mouse phantoms (50ml tubes) both in a groups of four at a time (multiple mice mode) and then individually (single mouse mode), using microPET/CT and microPET scanners to validate the process. Then, we imaged a first set of four mice with subcutaneous tumors (C2C12Ras) in both single- and multiple-mice imaging modes. Later, a second set of four normal mice were injected with FDG and scanned 1h post-injection. Immediately after completion of the scans, ex vivo biodistribution studies were performed on all animals to provide a "gold-standard" to compare quantitative values obtained from PET. A semi-automatic threshold-based region of interest tool was used to minimize operator variability during image analysis. RESULTS: Phantom studies showed less than 4.5% relative error difference between the single- and multiple-mice imaging modes of PET imaging with CT-based attenuation correction and 18.4% without CT-based attenuation correction. In vivo animal studies (n?=?4) showed <5% (for (64)Cu, p?>?0.686) and <15% (for FDG, p?>?0.4 except for brain image data p?=?0.029) relative mean difference with respect to percent injected dose per gram (%ID/gram) between the single- and multiple-mice microPET imaging mode when CT-based attenuation correction is performed. Without CT-based attenuation correction, we observed relative mean differences of about 11% for (64)Cu and 15% for FDG. CONCLUSION: Our results confirmed the potential use of a microPET/CT scanner for multiple mice simultaneous imaging without significant sacrifice in quantitative accuracy as well as in image quality. Thus, the use of the mouse "hotel" is an aid to increasing instrument throughput on small animal scanners with minimal loss of quantitative accuracy.

    View details for DOI 10.1007/s11307-012-0602-y

    View details for PubMedID 23479323

  • Evaluation of Zr-89-rituximab Tracer by Cerenkov Luminescence Imaging and Correlation with PET in a Humanized Transgenic Mouse Model to Image NHL MOLECULAR IMAGING AND BIOLOGY Natarajan, A., Habte, F., Liu, H., Sathirachinda, A., Hu, X., Cheng, Z., Nagamine, C. M., Gambhir, S. S. 2013; 15 (4): 468-475

    Abstract

    PURPOSE: This research aimed to study the use of Cerenkov luminescence imaging (CLI) for non-Hodgkin's lymphoma (NHL) using (89)Zr-rituximab positron emission tomography (PET) tracer with a humanized transgenic mouse model that expresses human CD20 and the correlation of CLI with PET. PROCEDURES: Zr-rituximab (2.6MBq) was tail vein-injected into transgenic mice that express the human CD20 on their B cells (huCD20TM). One group (n?=?3) received 2mg/kg pre-dose (blocking) of cold rituximab 2h prior to tracer; a second group (n?=?3) had no pre-dose (non-blocking). CLI was performed using a cooled charge-coupled device optical imager. We also performed PET imaging and ex vivo studies in order to confirm the in vivo CLI results. At each time point (4, 24, 48, 72, and 96h), two groups of mice were imaged in vivo and ex vivo with CLI and PET, and at 96h, organs were measured by gamma counter. RESULTS: huCD20 transgenic mice injected with (89)Zr-rituximab demonstrated a high-contrast CLI image compared to mice blocked with a cold dose. At various time points of 4-96h post-radiotracer injection, the in vivo CLI signal intensity showed specific uptake in the spleen where B cells reside and, hence, the huCD20 biomarker is present at very high levels. The time-activity curve of dose decay-corrected CLI intensity and percent injected dose per gram of tissue of PET uptake in the spleen were increased over the time period (4-96h). At 96h, the (89)Zr-rituximab uptake ratio (non-blocking vs blocking) counted (mean??standard deviation) for the spleen was 1.5??0.6 for CLI and 1.9??0.3 for PET. Furthermore, spleen uptake measurements (non-blocking and blocking of all time points) of CLI vs PET showed good correlation (R (2)?=?0.85 and slope?=?0.576), which also confirmed the corresponding correlations parameter value (R (2)?=?0.834 and slope?=?0.47) obtained for ex vivo measurements. CONCLUSIONS: CLI and PET of huCD20 transgenic mice injected with (89)Zr-rituximab demonstrated that the tracer was able to target huCD20-expressing B cells. The in vivo and ex vivo tracer uptake corresponding to the CLI radiance intensity from the spleen is in good agreement with PET. In this report, we have validated the use of CLI with PET for NHL imaging in huCD20TM.

    View details for DOI 10.1007/s11307-013-0624-0

    View details for Web of Science ID 000321972500014

    View details for PubMedID 23471750

  • F-18-Fluorobenzoate-Labeled Cystine Knot Peptides for PET Imaging of Integrin alpha(v)beta(6) JOURNAL OF NUCLEAR MEDICINE Hackel, B. J., Kimura, R. H., Miao, Z., Liu, H., Sathirachinda, A., Cheng, Z., Chin, F. T., Gambhir, S. S. 2013; 54 (7): 1101-1105

    Abstract

    Integrin ?v?6 is a cell surface receptor minimally expressed by healthy tissue but elevated in lung, colon, skin, ovarian, cervical, and pancreatic cancers. A molecular PET agent for integrin ?v?6 could provide significant clinical utility by facilitating both cancer staging and treatment monitoring to more rapidly identify an effective therapeutic approach. METHODS: Here, we evaluated 2 cystine knot peptides, R01 and S02, previously engineered with a 3-6 nM affinity for integrin ?v?6, for (18)F radiolabeling and PET imaging of BxPC3 pancreatic adenocarcinoma xenografts in mice. Cystine knot peptides were labeled with N-succinimidyl-4-(18)F-fluorobenzoate and evaluated for binding affinity and serum stability. Peptides conjugated with (18)F-fluorobenzoate (2-3 MBq) were injected via the tail vein into nude mice xenografted with BxPC3 (integrin ?v?6-positive) or 293 (integrin ?v?6-negative) tumors. Small-animal PET scans were acquired at 0.5, 1, and 2 h after injection. Ex vivo ?-counting of dissected tissues was performed at 0.5 and 2 h. RESULTS: (18)F-fluorobenzoate peptides were produced in 93% ((18)F-fluorobenzoate-R01) and 99% ((18)F-fluorobenzoate-S02) purity. (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02 had affinities of 1.1 0.2 and 0.7 0.4 nM, respectively, and were 87% and 94%, respectively, stable in human serum at 37C for 2 h. (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02 exhibited 2.3 0.6 and 1.3 0.4 percentage injected dose per gram (%ID/g), respectively, in BxPC3 xenografted tumors at 0.5 h (n = 4-5). Target specificity was confirmed by low tumor uptake in integrin ?v?6-negative 293 tumors (1.4 0.6 and 0.5 0.2 %ID/g, respectively, for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02; both P < 0.05; n = 3-4) and low muscle uptake (3.1 1.0 and 2.7 0.4 tumor to muscle for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02, respectively). Small-animal PET data were corroborated by ex vivo ?-counting of dissected tissues, which demonstrated low uptake in nontarget tissues with only modest kidney uptake (9.2 3.3 and 1.9 1.2 %ID/g, respectively, at 2 h for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02; n = 8). Uptake in healthy pancreas was low (0.3% 0.1% for (18)F-fluorobenzoate-R01 and 0.03% 0.01% for (18)F-fluorobenzoate-S02; n = 8). CONCLUSION: These cystine knot peptide tracers, in particular (18)F-fluorobenzoate-R01, show translational promise for molecular imaging of integrin ?v?6 overexpression in pancreatic and other cancers.

    View details for DOI 10.2967/jnumed.112.110759

    View details for Web of Science ID 000321113500019

  • First (18)F-labeled ligand for PET imaging of uPAR: In vivo studies in human prostate cancer xenografts. Nuclear medicine and biology Persson, M., Liu, H., Madsen, J., Cheng, Z., Kjaer, A. 2013; 40 (5): 618-624

    Abstract

    Urokinase-type plasminogen activator receptor (uPAR) is overexpressed in human prostate cancer and uPAR has been found to be associated with metastatic disease and poor prognosis. AE105 is a small linear peptide with high binding affinity to uPAR. We synthesized an N-terminal NOTA-conjugated version (NOTA-AE105) for development of the first (18)F-labeled uPAR positron-emission-tomography PET ligand using the Al(18)F radiolabeling method. In this study, the potential of (18)F-AlF-NOTA-AE105 to specifically target uPAR-positive prostate tumors was investigated.NOTA-conjugated AE105 was synthesized and radiolabeled with (18)F-AlF according to a recently published optimized protocol. The labeled product was purified by reverse phase high performance liquid chromatography RP-HPLC. The tumor targeting properties were evaluated in mice with subcutaneously inoculated PC-3 xenografts using small animal PET and ex vivo biodistribution studies. uPAR-binding specificity was studied by coinjection of an excess of a uPAR antagonist peptide AE105 analogue (AE152).NOTA-AE105 was labeled with (18)F-AlF in high radiochemical purity (>92%) and yield (92.7%) and resulted in a specific activity of greater than 20GBq/?mol. A high and specific tumor uptake was found. At 1h post injection, the uptake of (18)F-AlF-NOTA-AE105 in PC-3 tumors was 4.220.13%ID/g. uPAR-binding specificity was demonstrated by a reduced uptake of (18)F-AlF-NOTA-AE105 after coinjection of a blocking dose of uPAR antagonist at all three time points investigated. Good tumor-to-background ratio was observed with small animal PET and confirmed in the biodistribution analysis. Ex vivo uPAR expression analysis on extracted tumors confirmed human uPAR expression that correlated close with tumor uptake of (18)F-AlF-NOTA-AE105.The first (18)F-labeled uPAR PET ligand, (18)F-AlF-NOTA-AE105, has successfully been prepared and effectively visualized noninvasively uPAR positive prostate cancer. The favorable in vivo kinetics and easy production method facilitate its future clinical translation for identification of prostate cancer patients with an invasive phenotype and poor prognosis.

    View details for DOI 10.1016/j.nucmedbio.2013.03.001

    View details for PubMedID 23602763

  • Image-guided resection of malignant gliomas using ?uorescent nanoparticles. Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology Su, X., Cheng, K., Wang, C., Xing, L., Wu, H., Cheng, Z. 2013; 5 (3): 219-232

    Abstract

    Intraoperative fluorescence imaging especially near-infrared fluorescence (NIRF) imaging has the potential to revolutionize neurosurgery by providing high sensitivity and real-time image guidance to surgeons for defining gliomas margins. Fluorescence probes including targeted nanoprobes are expected to improve the specificity and selectivity for intraoperative fluorescence or NIRF tumor imaging. The main focus of this article is to provide a brief overview of intraoperative fluorescence imaging systems and probes including fluorescein sodium, 5-aminolevulinic acid, dye-containing nanoparticles, and targeted NIRF nanoprobes for their applications in image-guided resection of malignant gliomas. Moreover, photoacoustic imaging is a promising molecular imaging modality, and its potential applications for brain tumor imaging are also briefly discussed.

    View details for DOI 10.1002/wnan.1212

    View details for PubMedID 23378052

  • Fluorine-18 labeling by click chemistry: Multiple probes in one pot APPLIED RADIATION AND ISOTOPES Jia, L., Cheng, Z., Shi, L., Li, J., Wang, C., Jiang, D., Zhou, W., Meng, H., Qi, Y., Cheng, D., Zhang, L. 2013; 75: 64-70

    Abstract

    Click chemistry has been widely applied in drug development including radiopharmaceuticals and has shown great advantages. Here we reported a novel strategy for rapid preparation of multiple (18)F labeled PET probes in one pot using the 'Click Reaction' of Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition of terminal alkynes and organic azides (CuAAC). Preliminary results showed its high efficiency and potential for speeding up the preclinical screening of PET probes.

    View details for DOI 10.1016/j.apradiso.2013.01.033

    View details for Web of Science ID 000317558900012

    View details for PubMedID 23455406

  • Affibody modified and radiolabeled gold-Iron oxide hetero-nanostructures for tumor PET, optical and MR imaging BIOMATERIALS Yang, M., Cheng, K., Qi, S., Liu, H., Jiang, Y., Jiang, H., Li, J., Chen, K., Zhang, H., Cheng, Z. 2013; 34 (11): 2796-2806

    Abstract

    A highly monodispersed hetero-nanostructure with two different functional nanomaterials (gold (Au) and iron oxide (Fe(3)O(4,) IO)) within one structure was successfully developed as Affibody based trimodality nanoprobe (positron emission tomography, PET; optical imaging; and magnetic resonance imaging, MRI) for imaging of epidermal growth factor receptor (EGFR) positive tumors. Unlike other regular nanostructures with a single component, the Au-IO hetero-nanostructures (Au-IONPs) with unique chemical and physical properties have capability to combine several imaging modalities together to provide complementary information. The IO component within hetero-nanostructures serve as a T(2) reporter for MRI; and gold component serve as both optical and PET reporters. Moreover, such hetero-nanoprobes could provide a robust nano-platform for surface-specific modification with both targeting molecules (anti-EGFR Affibody protein) and PET imaging reporters (radiometal (64)Cu chelators) in highly efficient and reliable manner. In vitro and in vivo study showed that the resultant nanoprobe provided high specificity, sensitivity, and excellent tumor contrast for both PET and MRI imaging in the human EGFR-expressing cells and tumors. Our study data also highlighted the EGFR targeting efficiency of hetero-nanoparticles and the feasibility for their further theranostic applications.

    View details for DOI 10.1016/j.biomaterials.2013.01.014

    View details for Web of Science ID 000315748200022

    View details for PubMedID 23343632

  • Tyrosinase as a multifunctional reporter gene for Photoacoustic/MRI/PET triple modality molecular imaging SCIENTIFIC REPORTS Qin, C., Cheng, K., Chen, K., Hu, X., Liu, Y., Lan, X., Zhang, Y., Liu, H., Xu, Y., Bu, L., Su, X., Zhu, X., Meng, S., Cheng, Z. 2013; 3

    Abstract

    Development of reporter genes for multimodality molecular imaging is highly important. In contrast to the conventional strategies which have focused on fusing several reporter genes together to serve as multimodal reporters, human tyrosinase (TYR) - the key enzyme in melanin production - was evaluated in this study as a stand-alone reporter gene for in vitro and in vivo photoacoustic imaging (PAI), magnetic resonance imaging (MRI) and positron emission tomography (PET). Human breast cancer cells MCF-7 transfected with a plasmid that encodes TYR (named as MCF-7-TYR) and non-transfected MCF-7 cells were used as positive and negative controls, respectively. Melanin targeted N-(2-(diethylamino)ethyl)-(18)F-5-fluoropicolinamide was used as a PET reporter probe. In vivo PAI/MRI/PET imaging studies showed that MCF-7-TYR tumors achieved significant higher signals and tumor-to-background contrasts than those of MCF-7 tumor. Our study demonstrates that TYR gene can be utilized as a multifunctional reporter gene for PAI/MRI/PET both in vitro and in vivo.

    View details for DOI 10.1038/srep01490

    View details for Web of Science ID 000316251200007

    View details for PubMedID 23508226

  • Development of F-18-Labeled Picolinamide Probes for PET Imaging of Malignant Melanoma JOURNAL OF MEDICINAL CHEMISTRY Liu, H., Liu, S., Miao, Z., Deng, Z., Shen, B., Hong, X., Cheng, Z. 2013; 56 (3): 895-901

    Abstract

    Melanoma is an aggressive skin cancer with worldwide increasing incidence. Development of positron emission tomography (PET) probes for early detection of melanoma is critical for improving the survival rate of melanoma patients. In this research, (18)F-picolinamide-based PET probes were prepared by direct radiofluorination of the bromopicolinamide precursors using no-carrier-added (18)F-fluoride. The resulting probes, (18)F-1, (18)F-2 and (18)F-3, were then evaluated in vivo by small animal PET imaging and biodistribution studies in C57BL/6 mice bearing B16F10 murine melanoma tumors. Noninvasive small animal PET studies demonstrated excellent tumor imaging contrasts for all probes, while (18)F-2 showed higher tumor to muscle ratios than (18)F-1 and (18)F-3. Furthermore, (18)F-2 demonstrated good in vivo stability as evidenced by the low bone uptake in biodistribution studies. Collectively, these findings suggest (18)F-2 as a highly promising PET probe for translation into clinical detection of melanoma.

    View details for DOI 10.1021/jm301740k

    View details for Web of Science ID 000315182100023

    View details for PubMedID 23301672

  • A novel radiofluorinated agouti-related protein for tumor angiogenesis imaging AMINO ACIDS Jiang, H., Moore, S. J., Liu, S., Liu, H., Miao, Z., Cochran, F. V., Liu, Y., Tian, M., Cochran, J. R., Zhang, H., Cheng, Z. 2013; 44 (2): 673-681

    Abstract

    A novel protein scaffold based on the cystine knot domain of the agouti-related protein (AgRP) has been used to engineer mutants that can bind to the ?(v)?(3) integrin receptor with high affinity and specificity. In the current study, an (18)F-labeled AgRP mutant (7C) was prepared and evaluated as a positron emission tomography (PET) probe for imaging tumor angiogenesis. AgRP-7C was synthesized by solid phase peptide synthesis and site-specifically conjugated with 4-nitrophenyl 2-(18/19)F-fluoropropionate ((18/19)F-NFP) to produce the fluorinated peptide, (18/19)F-FP-AgRP-7C. Competition binding assays were used to measure the relative affinities of AgRP-7C and (19)F-FP-AgRP-7C to human glioblastoma U87MG cells that overexpress ?(v)?(3) integrin. In addition, biodistribution, metabolic stability, and small animal PET imaging studies were conducted with (18)F-FP-AgRP-7C using U87MG tumor-bearing mice. Both AgRP-7C and (19)F-FP-AgRP-7C specifically competed with (125)I-echistatin for binding to U87MG cells with half maximal inhibitory concentration (IC(50)) values of 9.40 and 8.37 nM, respectively. Non-invasive small animal PET imaging revealed that (18)F-FP-AgRP-7C exhibited rapid and good tumor uptake (3.24 percentage injected dose per gram [% ID/g] at 0.5h post injection [p.i.]). The probe was rapidly cleared from the blood and from most organs, resulting in excellent tumor-to-normal tissue contrasts. Tumor uptake and rapid clearance were further confirmed with biodistribution studies. Furthermore, co-injection of (18)F-FP-AgRP-7C with a large molar excess of blocking peptide c(RGDyK) significantly inhibited tumor uptake in U87MG xenograft models, demonstrating the integrin-targeting specificity of the probe. Metabolite assays showed that the probe had high stability, making it suitable for in vivo applications. (18)F-FP-AgRP-7C exhibits promising in vivo properties such as rapid tumor targeting, good tumor uptake, and excellent tumor-to-normal tissue ratios, and warrants further investigation as a novel PET probe for imaging tumor angiogenesis.

    View details for DOI 10.1007/s00726-012-1391-y

    View details for Web of Science ID 000313794600036

    View details for PubMedID 22945905

  • Molecular imaging of hepatocellular carcinoma xenografts with epidermal growth factor receptor targeted affibody probes. BioMed research international Zhao, P., Yang, X., Qi, S., Liu, H., Jiang, H., Hoppmann, S., Cao, Q., Chua, M., So, S. K., Cheng, Z. 2013; 2013: 759057-?

    Abstract

    Hepatocellular carcinoma (HCC) is a highly aggressive and lethal cancer. It is typically asymptomatic at the early stage, with only 10%-20% of HCC patients being diagnosed early enough for appropriate surgical treatment. The delayed diagnosis of HCC is associated with limited treatment options and much lower survival rates. Therefore, the early and accurate detection of HCC is crucial to improve its currently dismal prognosis. The epidermal growth factor receptor (EGFR) has been reported to be involved in HCC tumorigenesis and to represent an attractive target for HCC imaging and therapy. In this study, an affibody molecule, Ac-Cys-ZEGFR:1907, targeting the extracellular domain of EGFR, was used for the first time to assess its potential to detect HCC xenografts. By evaluating radio- or fluorescent-labeled Ac-Cys-ZEGFR:1907 as a probe for positron emission tomography (PET) or optical imaging of HCC, subcutaneous EGFR-positive HCC xenografts were found to be successfully imaged by the PET probe. Thus, affibody-based PET imaging of EGFR provides a promising approach for detecting HCC in vivo.

    View details for DOI 10.1155/2013/759057

    View details for PubMedID 23710458

  • 177Lu-labeled RGD-BBN heterodimeric peptide for targeting prostate carcinoma. Nuclear medicine communications Jiang, L., Miao, Z., Liu, H., Ren, G., Bao, A., Cutler, C. S., Shi, H., Cheng, Z. 2013

    Abstract

    INTRODUCTION: Radiolabeled Arg-Gly-Asp (RGD) and bombesin (BBN) heterodimers have been investigated for dual targeting of tumor integrin ?v?3 receptors and gastrin-releasing peptide receptors. The goal of this study was to evaluate the potential use of a Lu-labeled RGD-BBN heterodimer for targeted prostate cancer therapy. MATERIALS AND METHODS: A 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-conjugated RGD-BBN peptide (DO3A-RGD-BBN) was radiolabeled with Lu and purified by high-performance liquid chromatography. The in-vivo biodistribution study of Lu-DO3A-RGD-BBN was carried out in mice bearing human prostate cancer PC3 xenografts. The receptor-targeting specificity of the radiolabeled peptide was assayed by injecting the tracer with the unlabeled RGD-BBN peptide. Radiation absorbed doses in adult male patients, based on biodistribution data from mice, were also calculated. RESULTS: DO3A-RGD-BBN peptides were successfully labeled with Lu, and high radiochemical purity (>95%) could be achieved after high-performance liquid chromatography purification. In human PC3 xenograft-bearing mice, the tumor accumulation of Lu-DO3A-RGD-BBN was 5.881.12, 2.770.30, 2.040.19, and 1.180.19%ID/g at 0.5, 2, 24, and 48 h, respectively. With rapid clearance from normal tissues, the radiolabeled probe displayed high tumor-to-blood and tumor-to-muscle ratios. On calculating the radiation absorbed doses for Lu-DO3A-RGD-BBN, we found that the prostate tumor and the pancreas were the organs receiving the highest radiation absorbed doses. CONCLUSION: Dual integrin ?v?3 and GPRP-targeted agent Lu-DO3A-RGD-BBN shows excellent prostate cancer-targeting ability, and it is worthy of further evaluation for prostate cancer-targeted therapy.

    View details for PubMedID 23708872

  • Continuous sensing of tumor-targeted molecular probes with a vertical cavity surface emitting laser-based biosensor JOURNAL OF BIOMEDICAL OPTICS Parashurama, N., O'Sullivan, T. D., de la Zerda, A., El Kalassi, P., Cho, S., Liu, H., Teed, R., Levy, H., Rosenberg, J., Cheng, Z., Levi, O., Harris, J. S., Gambhir, S. S. 2012; 17 (11)

    Abstract

    Molecular optical imaging is a widespread technique for interrogating molecular events in living subjects. However, current approaches preclude long-term, continuous measurements in awake, mobile subjects, a strategy crucial in several medical conditions. Consequently, we designed a novel, lightweight miniature biosensor for in vivo continuous optical sensing. The biosensor contains an enclosed vertical-cavity surface-emitting semiconductor laser and an adjacent pair of near-infrared optically filtered detectors. We employed two sensors (dual sensing) to simultaneously interrogate normal and diseased tumor sites. Having established the sensors are precise with phantom and in vivo studies, we performed dual, continuous sensing in tumor (human glioblastoma cells) bearing mice using the targeted molecular probe cRGD-Cy5.5, which targets ?V?3 cell surface integrins in both tumor neovasculature and tumor. The sensors capture the dynamic time-activity curve of the targeted molecular probe. The average tumor to background ratio after signal calibration for cRGD-Cy5.5 injection is approximately 2.430.95 at 1 h and 3.641.38 at 2 h (N=5 mice), consistent with data obtained with a cooled charge coupled device camera. We conclude that our novel, portable, precise biosensor can be used to evaluate both kinetics and steady state levels of molecular probes in various disease applications.

    View details for DOI 10.1117/1.JBO.17.11.117004

    View details for Web of Science ID 000314502700046

    View details for PubMedID 23123976

  • Novel, Cysteine-Modified Chelation Strategy for the Incorporation of [M-I(CO)(3)](+) (M = Re, Tc-99m) in an alpha-MSH Peptide BIOCONJUGATE CHEMISTRY Jiang, H., Kasten, B. B., Liu, H., Qi, S., Liu, Y., Tian, M., Barnes, C. L., Zhang, H., Cheng, Z., Benny, P. D. 2012; 23 (11): 2300-2312

    Abstract

    Engineering peptide-based targeting agents with residues for site-specific and stable complexation of radionuclides is a highly desirable strategy for producing diagnostic and therapeutic agents for cancer and other diseases. In this report, a model N-S-N(Py) ligand (3) and a cysteine-derived ?-melanocyte stimulating hormone (?-MSH) peptide (6) were used as novel demonstrations of a widely applicable chelation strategy for incorporation of the [M(I)(CO)(3)](+) (M = Re, (99m)Tc) core into peptide-based molecules for radiopharmaceutical applications. The structural details of the core ligand-metal complexes as model systems were demonstrated by full chemical characterization of fac-[Re(I)(CO)(3)(N,S,N(Py)-3)](+) (4) and comparative high-performance liquid chromatography (HPLC) analysis between 4 and [(99m)Tc(I)(CO)(3)(N,S,N(Py)-3)](+) (4a). The ?-MSH analogue bearing the N-S-N(Py) chelate on a modified cysteine residue (6) was generated and complexed with [M(I)(CO)(3)](+) to confirm the chelation strategy's utility when applied in a peptide-based targeting agent. Characterization of the Re(I)(CO)(3)-6 peptide conjugate (7) confirmed the efficient incorporation of the metal center, and the (99m)Tc(I)(CO)(3)-6 analogue (7a) was explored as a potential single photon emission computed tomography (SPECT) compound for imaging the melanocortin 1 receptor (MC1R) in melanoma. Peptide 7a showed excellent radiolabeling yields and in vitro stability during amino acid challenge and serum stability assays. In vitro B16F10 melanoma cell uptake of 7a reached a modest value of 2.3 0.08% of applied activity at 2 h at 37 C, while this uptake was significantly reduced by coincubation with a nonlabeled ?-MSH analogue, NAPamide (3.2 ?M) (P < 0.05). In vivo SPECT/X-ray computed tomography (SPECT/CT) imaging and biodistribution of 7a were evaluated in a B16F10 melanoma xenografted mouse model. SPECT/CT imaging clearly visualized the tumor at 1 h post injection (p.i.) with high tumor-to-background contrast. Blocking studies with coinjected NAPamide (10 mg per kg of mouse body weight) confirmed the in vivo specificity of 7a for MC1R-positive tumors. Biodistribution results with 7a yielded a moderate tumor uptake of 1.20 0.09 percentage of the injected radioactive dose per gram of tissue (% ID/g) at 1 h p.i. Relatively high uptake of 7a was also seen in the kidneys and liver at 1 h p.i. (6.55 0.36% ID/g and 4.44 0.17% ID/g, respectively), although reduced kidney uptake was seen at 4 h p.i. (3.20 0.48% ID/g). These results demonstrate the utility of the novel [M(I)(CO)(3)](+) chelation strategy when applied in a targeting peptide.

    View details for DOI 10.1021/bc300509k

    View details for Web of Science ID 000311325000017

    View details for PubMedID 23110503

  • Near Infrared Receptor-Targeted Nanoprobes for Early Diagnosis of Cancers CURRENT MEDICINAL CHEMISTRY Cheng, K., Cheng, Z. 2012; 19 (28): 4767-4785

    Abstract

    The success of detecting cancer at early stages relies greatly on the sensitivity and specificity of in vivo molecular imaging. Optical imaging with near infrared (NIR) luminescent molecular nanoprobes currently attracts much attention because of many advantages of this imaging modality. It provides real time imaging with relatively inexpensive cost, produces images with high sensitivity and spatial resolution, and avoids exposure to ionizing irradiation. Raman spectroscopy/microscopy imaging with surface enhanced Raman scattering (SERS) nanoparticles allows scientists to detect biological events in living cells or organisms in real time and with high sensitivity. The photoacoustic imaging has emerged as a hybrid of optical and ultrasound imaging for sensitive and quantitative tumor detection. Given the recent advances in nanoscience and biomedicine, receptor-targeted NIR nanoprobes promise to improve the cancer early detection with relatively high sensitivity and specificity. We summarize various targeted NIR nanoprobes and their potential applications in cancer targeting and in vivo imaging and discuss the potential of multimodality imaging of NIR nanoprobes. With ongoing efforts to enhance their targeting ability and endow more functions, NIR nanoprobes hold great promise for clinical translation.

    View details for Web of Science ID 000309745800006

    View details for PubMedID 22873665

  • Intraoperative Imaging of Tumors Using Cerenkov Luminescence Endoscopy: A Feasibility Experimental Study JOURNAL OF NUCLEAR MEDICINE Liu, H., Carpenter, C. M., Jiang, H., Pratx, G., Sun, C., Buchin, M. P., Gambhir, S. S., Xing, L., Cheng, Z. 2012; 53 (10): 1579-1584

    Abstract

    Cerenkov luminescence imaging (CLI) is an emerging new molecular imaging modality that is relatively inexpensive, easy to use, and has high throughput. CLI can image clinically available PET and SPECT probes using optical instrumentation. Cerenkov luminescence endoscopy (CLE) is one of the most intriguing applications that promise potential clinical translation. We developed a prototype customized fiberscopic Cerenkov imaging system to investigate the potential in guiding minimally invasive surgical resection.All experiments were performed in a dark chamber. Cerenkov luminescence from (18)F-FDG samples containing decaying radioactivity was transmitted through an optical fiber bundle and imaged by an intensified charge-coupled device camera. Phantoms filled with (18)F-FDG were used to assess the imaging spatial resolution. Finally, mice bearing subcutaneous C6 glioma cells were injected intravenously with (18)F-FDG to determine the feasibility of in vivo imaging. The tumor tissues were exposed, and CLI was performed on the mouse before and after surgical removal of the tumor using the fiber-based imaging system and compared with a commercial optical imaging system.The sensitivity of this particular setup was approximately 45 kBq (1.21 ?Ci)/300 ?L. The 3 smallest sets of cylindric holes in a commercial SPECT phantom were identifiable via this system, demonstrating that the system has a resolution better than 1.2 mm. Finally, the in vivo tumor imaging study demonstrated the feasibility of using CLI to guide the resection of tumor tissues.This proof-of-concept study explored the feasibility of using fiber-based CLE for the detection of tumor tissue in vivo for guided surgery. With further improvements of the imaging sensitivity and spatial resolution of the current system, CLE may have a significant application in the clinical setting in the near future.

    View details for DOI 10.2967/jnumed.111.098541

    View details for Web of Science ID 000309432400017

    View details for PubMedID 22904353

  • The manipulation of natural killer cells to target tumor sites using magnetic nanoparticles BIOMATERIALS Jang, E., Shin, J., Ren, G., Park, M., Cheng, K., Chen, X., Wu, J. C., Sunwoo, J. B., Cheng, Z. 2012; 33 (22): 5584-5592

    Abstract

    The present work demonstrates that Cy5.5 conjugated Fe(3)O(4)/SiO(2) core/shell nanoparticles could allow us to control movement of human natural killer cells (NK-92MI) by an external magnetic field. Required concentration of the nanoparticles for the cell manipulation is as low as ~20 ?g Fe/mL. However, the relative ratio of the nanoparticles loaded NK-92MI cells infiltrated into the target tumor site is enhanced by 17-fold by applying magnetic field and their killing activity is still maintained as same as the NK-92MI cells without the nanoparticles. This approach allows us to open alternative clinical treatment with reduced toxicity of the nanoparticles and enhanced infiltration of immunology to the target site.

    View details for DOI 10.1016/j.biomaterials.2012.04.041

    View details for Web of Science ID 000305366500010

    View details for PubMedID 22575830

  • A multimodality reporter gene for monitoring transplanted stem cells NUCLEAR MEDICINE AND BIOLOGY Pei, Z., Lan, X., Cheng, Z., Qin, C., Wang, P., He, Y., Yen, T., Tian, Y., Mghanga, F. P., Zhang, Y. 2012; 39 (6): 813-820

    Abstract

    The aim of this study is to explore the feasibility of a triple-fused reporter gene, termed TGF [herpes simplex virus type 1 thymidine kinase (HSV1-tk), enhanced green fluorescent protein (eGFP) and firefly luciferase (Fluc)], to monitor stem cells using multimodality molecular imaging.A recombinant adenovirus vector carrying the triple-fused reporter gene (Ad5-TGF) was constructed. Bone marrow mesenchymal stem cells (BMSCs) were transfected with different virus titers of Ad5-TGF [multiplicities of infection (MOIs) were 0, 50, 100, 150, 200 and 250]. The mRNA and protein expressions of HSV1-tk, eGFP and Fluc in the transfected BMSCs were evaluated using polymerase chain reaction and Western blot. After the transfection of the BMSCs with different virus titers of Ad5-TGF (MOIs were 25, 50, 75, 100 and 125), their uptake rates of (131)I-FIAU were measured. Whole-body fluorescence, bioluminescence and micro-positron emission tomography (PET) images were acquired 1 day after the transfected BMSCs were injected into the left forelimb of rats.After the transfection with different titers of Ad5-TGF, the positive transfection rate reached a peak (70%) when the MOI was 100. HSV1-tk, eGFP and Fluc mRNA and protein were detected in the Ad5-TGF-transfected BMSCs, which implies their successful transfection and expression. The BMSCs uptake of (131)I-FIAU increased with the adenovirus titer and incubation time and reached a plateau (approximately 5.3%) after 3 h. Strong signals were observed in the injected left forearms in the fluorescence, bioluminescence and micro-PET images.A triple-fused reporter gene, TGF, can be used as a multifunctional molecular probe for multimodality imaging.

    View details for DOI 10.1016/j.nucmedbio.2011.12.014

    View details for Web of Science ID 000307041000009

    View details for PubMedID 22336371

  • Activatable Near-Infrared Fluorescent Probe for In Vivo Imaging of Fibroblast Activation Protein-alpha BIOCONJUGATE CHEMISTRY Li, J., Chen, K., Liu, H., Cheng, K., Yang, M., Zhang, J., Cheng, J. D., Zhang, Y., Cheng, Z. 2012; 23 (8): 1704-1711

    Abstract

    Fibroblast activation protein-alpha (FAP?) is a cell surface glycoprotein which is selectively expressed by tumor-associated fibroblasts in malignant tumors but rarely on normal tissues. FAP? has also been reported to promote tumor growth and invasion and therefore has been of increasing interest as a promising target for designing tumor-targeted drugs and imaging agents. Although medicinal study on FAP? inhibitors has led to the discovery of many FAP?-targeting inhibitors including a drug candidate in a phase II clinical trial, the development of imaging probes to monitor the expression and activity of FAP? in vivo has largely lagged behind. Herein, we report an activatable near-infrared (NIR) fluorescent probe (ANP(FAP)) for in vivo optical imaging of FAP?. The ANP(FAP) consists of a NIR dye (Cy5.5) and a quencher dye (QSY21) which are linked together by a short peptide sequence (KGPGPNQC) specific for FAP? cleavage. Because of the efficient fluorescence resonance energy transfer (FRET) between Cy5.5 and QSY21 in ANP(FAP), high contrast on the NIR fluorescence signal can be achieved after the cleavage of the peptide sequence by FAP? both in vitro and in vivo. In vitro assay on ANP(FAP) indicated the specificity of the probe to FAP?. The in vivo optical imaging using ANP(FAP) showed fast tumor uptake as well as high tumor to background contrast on U87MG tumor models with FAP? expression, while much lower signal and tumor contrast were observed in the C6 tumor without FAP? expression, demonstrating the in vivo targeting specificity of the ANP(FAP). Ex vivo imaging also demonstrated ANP(FAP) had high tumor uptake at 4 h post injection. Collectively, these results indicated that ANP(FAP) could serve as a useful NIR optical probe for early detection of FAP? expressing tumors.

    View details for DOI 10.1021/bc300278r

    View details for Web of Science ID 000307487300021

    View details for PubMedID 22812530

  • In vivo targeting of HER2-positive tumor using 2-helix affibody molecules AMINO ACIDS Ren, G., Webster, J. M., Liu, Z., Zhang, R., Miao, Z., Liu, H., Gambhir, S. S., Syud, F. A., Cheng, Z. 2012; 43 (1): 405-413

    Abstract

    Molecular imaging of human epidermal growth factor receptor type 2 (HER2) expression has drawn significant attention because of the unique role of the HER2 gene in diagnosis, therapy and prognosis of human breast cancer. In our previous research, a novel cyclic 2-helix small protein, MUT-DS, was discovered as an anti-HER2 Affibody analog with high affinity through rational protein design and engineering. MUT-DS was then evaluated for positron emission tomography (PET) of HER2-positive tumor by labeling with two radionuclides, 68Ga and 18F, with relatively short half-life (t1/2<2 h). In order to fully study the in vivo behavior of 2-helix small protein and demonstrate that it could be a robust platform for labeling with a variety of radionuclides for different applications, in this study, MUT-DS was further radiolabeled with 64Cu or 111In and evaluated for in vivo targeting of HER2-positive tumor in mice. Design 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugated MUT-DS (DOTA-MUT-DS) was chemically synthesized using solid phase peptide synthesizer and I2 oxidation. DOTA-MUT-DS was then radiolabeled with 64Cu or 111In to prepare the HER2 imaging probe (64Cu/111In-DOTA-MUT-DS). Both biodistribution and microPET imaging of the probe were evaluated in nude mice bearing subcutaneous HER2-positive SKOV3 tumors. DOTA-MUT-DS could be successfully synthesized and radiolabeled with 64Cu or 111In. Biodistribution study showed that tumor uptake value of 64Cu or 111In-labeled DOTA-MUT-DS was 4.660.38 or 2.170.15%ID/g, respectively, in nude mice bearing SKOV3 xenografts (n=3) at 1 h post-injection (p.i.). Tumor-to-blood and tumor-to-muscle ratios for 64Cu-DOTA-MUT-DS were attained to be 3.05 and 3.48 at 1 h p.i., respectively, while for 111In-DOTA-MUT-DS, they were 2.04 and 3.19, respectively. Co-injection of the cold Affibody molecule ZHER2:342 with 64Cu-DOTA-MUT-DS specifically reduced the SKOV3 tumor uptake of the probe by 48%. 111In-DOTA-MUT-DS displayed lower liver uptake at all the time points investigated and higher tumor to blood ratios at 4 and 20 h p.i., when compared with 64Cu-DOTA-MUT-DS. This study demonstrates that the 2-helix protein based probes, 64Cu/111In DOTA-MUT-DS, are promising molecular probes for imaging HER2-positive tumor. Two-helix small protein scaffold holds great promise as a novel and robust platform for imaging and therapy applications.

    View details for DOI 10.1007/s00726-011-1096-7

    View details for Web of Science ID 000305210800041

    View details for PubMedID 21984380

  • PET of EGFR Expression with an F-18-Labeled Affibody Molecule JOURNAL OF NUCLEAR MEDICINE Miao, Z., Ren, G., Liu, H., Qi, S., Wu, S., Cheng, Z. 2012; 53 (7): 1110-1118

    Abstract

    Epidermal growth factor receptor (EGFR) is often overexpressed in a variety of human cancers, and its expression is associated with poor prognosis for many cancer types. However, an accurate technique to noninvasively image EGFR expression in vivo is not available in the clinical setting. In this research, an Affibody analog, anti-EGFR Ac-Cys-Z(EGFR:1907), was successfully site-specifically (18)F-labeled for PET of EGFR expression.The prosthetic group N-[2-(4-(18)F-fluorobenzamido) ethyl] maleimide ((18)F-FBEM) was conjugated to Ac-Cys-Z(EGFR:1907) under mild conditions (pH 7) to produce the probe (18)F-FBEM-Cys-Z(EGFR:1907). The binding affinity and specificity tests of (18)F-FBEM-Cys-Z(EGFR:1907) to EGFR were conducted using A431 cancer cells. Small-animal PET and biodistribution studies were conducted on various mice tumor xenograft models with EGFR overexpression (6 types) after injection of approximately 2.0 MBq of (18)F-FBEM-Cys-Z(EGFR:1907) with or without coinjection of unlabeled Ac-Cys-Z(EGFR:1907) for up to 3 h after injection. A correlation study between (18)F-FBEM-Cys-Z(EGFR:1907) small- animal PET quantification and ex vivo Western blot analysis of tumor EGFR expression was conducted in those 6 types of tumor models.(18)F-FBEM-Cys-Z(EGFR:1907) binds to EGFR with low nanomolar affinity (37 nM) in A431 cells. (18)F-FBEM-Cys-Z(EGFR:1907) rapidly accumulated in the tumor and cleared from most of the normal organs except the liver and kidneys at 3 h after injection, allowing excellent tumor-to-normal tissue contrast to be obtained. In the A431 tumor xenograft model, coinjection of the PET probe with 45 ?g of Ac-Cys-Z(EGFR:1907) was able to improve the tumor uptake (3.9 vs. 8.1 percentage of the injected radioactive dose per gram of tissue, at 3 h after injection) and tumor imaging contrast, whereas coinjection with 500 ?g of Ac-Cys-Z(EGFR:1907) successfully blocked the tumor uptake significantly (8.1 vs. 1.0 percentage of the injected radioactive dose per gram of tissue, at 3 h after injection, 88% inhibition, P < 0.05). Moderate correlation was found between the tumor tracer uptake at 3 h after injection quantified by PET and EGFR expression levels measured by Western blot assay (P = 0.007, R = 0.59).(18)F-FBEM-Cys-Z(EGFR:1907) is a novel protein scaffold-based PET probe for imaging EGFR overexpression of tumors, and its ability to differentiate tumors with high and low EGFR expression in vivo holds promise for future clinical translation.

    View details for DOI 10.2967/jnumed.111.100842

    View details for Web of Science ID 000306164600028

    View details for PubMedID 22689926

  • Assessment and comparison of magnetic nanoparticles as MRI contrast agents in a rodent model of human hepatocellular carcinoma CONTRAST MEDIA & MOLECULAR IMAGING Bu, L., Xie, J., Chen, K., Huang, J., Aguilar, Z. P., Wang, A., Sun, K. W., Chua, M., So, S., Cheng, Z., Eden, H. S., Shen, B., Chen, X. 2012; 7 (4): 363-372

    Abstract

    The purpose of this study was to synthesize, characterize and tailor the surface properties of magnetic nanoparticles with biocompatible copolymer coatings and to evaluate the efficiency of the resulting nanoconjugates as magnetic resonance imaging (MRI) contrast agents for liver imaging. Magnetic nanoparticles with core diameters of 10 and 30 nm were synthesized by pyrolysis and were subsequently coated with a copolymer containing either carboxyl (SHP) or methoxy groups as termini. All four formulas, and ferumoxides (Feridex I.V.()), were individually injected intravenously into separate, normal Balb/C mice (at 2.5, 1.0 and 0.56 mg Fe kg(-1)), and the animals underwent T(2)-weighted MRI at multiple time points post injection (p.i.) to evaluate the hepatic uptake and clearance. Furthermore, we compared the abilities of the new formulas and Feridex to detect tumors in an orthotropic Huh7 tumor model. Transmission electron microscopy (TEM) revealed a narrow size distribution of both the 10 and 30 nm nanoparticles, in contrast to a wide size distribution of Feridex. MTT, apoptosis and cyclin/DNA flow cytometry assays showed that the polymer coated nanoparticles had no adverse effect on cell growth. Among all the tested formulas, including Feridex, SHP-30 showed the highest macrophage uptake at the in vitro level. In vivo MRI studies on normal mice confirmed the superiority of SHP-30 in inducing hypointensities in the liver tissue, especially at clinical dose (0.56 mg Fe kg(-1)) and 3?T field. SHP-30 showed better contrast-to-noise ratio than Feridex on the orthotropic Huh7 tumor model. SHP-30 was found to be an efficient contrast agent for liver MR imaging. The success of this study suggests that, by improving the synthetic approach and by tuning the surface properties of IONPs, one can arrive at better formulas than Feridex for clinical practice.

    View details for DOI 10.1002/cmmi.494

    View details for Web of Science ID 000304665100002

    View details for PubMedID 22649042

  • Lu-177-DO3A-HSA-Z(EGFR:1907): characterization as a potential radiopharmaceutical for radionuclide therapy of EGFR-expressing head and neck carcinomas JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY Hoppmann, S., Qi, S., Miao, Z., Liu, H., Jiang, H., Cutler, C. S., Bao, A., Cheng, Z. 2012; 17 (5): 709-718

    Abstract

    Epidermal growth factor receptor 1 (EGFR) is an attractive target for radionuclide therapy of head and neck carcinomas. Affibody molecules against EGFR (Z(EGFR)) show excellent tumor localizations in imaging studies. However, one major drawback is that radiometal-labeled Affibody molecules display extremely high uptakes in the radiosensitive kidneys which may impact their use as radiotherapeutic agents. The purpose of this study is to further explore whether radiometal-labeled human serum albumin (HSA)-Z(EFGR) bioconjugates display desirable profiles for the use in radionuclide therapy of EGFR-positive head and neck carcinomas. The Z(EFGR) analog, Ac-Cys-Z(EGFR:1907), was site-specifically conjugated with HSA. The resulting bioconjugate 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A)-HSA-Z(EGFR:1907) was then radiolabeled with either (64)Cu or (177)Lu and subjected to in vitro cell uptake and internalization studies using the human oral squamous carcinoma cell line SAS. Positron emission tomography (PET), single photon emission computed tomography (SPECT), and biodistribution studies were conducted using SAS-tumor-bearing mice. Cell studies revealed a high (8.43 0.55 % at 4 h) and specific (0.95 0.09 % at 4 h) uptake of (177)Lu-DO3A-HSA-Z(EGFR:1907) as determined by blocking with nonradioactive Z(EGFR:1907). The internalization of (177)Lu-DO3A-HSA-Z(EGFR:1907) was verified in vitro and found to be significantly higher than that of (177)Lu-labeled Z(EFGR) at 2-24 h of incubation. PET and SPECT studies showed good tumor imaging contrasts. The biodistribution of (177)Lu-DO3A-HSA-Z(EGFR:1907) in SAS-tumor-bearing mice displayed high tumor uptake (5.1 0.44 % ID/g) and liver uptake (31.5 7.66 % ID/g) and moderate kidney uptake (8.5 1.08 % ID/g) at 72 h after injection. (177)Lu-DO3A-HSA-Z(EGFR:1907) shows promising in vivo profiles and may be a potential radiopharmaceutical for radionuclide therapy of EGFR-expressing head and neck carcinomas.

    View details for DOI 10.1007/s00775-012-0890-3

    View details for Web of Science ID 000304566400004

    View details for PubMedID 22418921

  • Human Serum Albumin Conjugated Biomolecules for Cancer Molecular Imaging CURRENT PHARMACEUTICAL DESIGN Yang, M., Hoppmann, S., Chen, L., Cheng, Z. 2012; 18 (8): 1023-1031

    Abstract

    Molecular imaging is a fast growing field in biomedical research. The discovery, development and continual improvement of molecular probes are important for ongoing research efforts in molecular imaging. Human serum albumin (HSA) offers favorable characteristics and opportunities as a platform protein for molecular imaging probe discovery and optimization. It has many advantages, including alternation of biodistribution and pharmacokinetic properties of molecular imaging probes, enhancing the blood half-life of bio-molecules, and making these molecules multivalent, all of which make HSA a promising carrier for cancer-targeted imaging and therapy. Numerous studies have focused on the development and application of HSA-based cancer imaging and treatment. This review gives a brief account of albumin-based molecular probes, focusing on their applications in cancer molecular imaging, such as PET/SPECT, MRI and optical imaging.

    View details for Web of Science ID 000304445900002

    View details for PubMedID 22272822

  • Optical Imaging with Her2-Targeted Affibody Molecules Can Monitor Hsp90 Treatment Response in a Breast Cancer Xenograft Mouse Model CLINICAL CANCER RESEARCH van de Ven, S. M., Elias, S. G., Chan, C. T., Miao, Z., Cheng, Z., De, A., Gambhir, S. S. 2012; 18 (4): 1073-1081

    Abstract

    To determine whether optical imaging can be used for in vivo therapy response monitoring as an alternative to radionuclide techniques. For this, we evaluated the known Her2 response to 17-dimethylaminoethylamino-17-demethoxygeldanamycin hydrochloride (17-DMAG) treatment, an Hsp90 inhibitor.After in vitro 17-DMAG treatment response evaluation of MCF7 parental cells and 2 HER2-transfected clones (clone A medium, B high Her2 expression), we established human breast cancer xenografts in nude mice (only parental and clone B) for in vivo evaluation. Mice received 120 mg/kg of 17-DMAG in 4 doses at 12-hour intervals intraperitonially (n = 14) or PBS as carrier control (n = 9). Optical images were obtained both pretreatment (day 0) and posttreatment (day 3, 6, and 9), always 5 hours postinjection of 500 pmol of anti-Her2 Affibody-AlexaFluor680 via tail vein (with preinjection background subtraction). Days 3 and 9 in vivo optical imaging signal was further correlated with ex vivo Her2 levels by Western blot after sacrifice.Her2 expression decreased with 17-DMAG dose in vitro. In vivo optical imaging signal was reduced by 22.5% in clone B (P = 0.003) and by 9% in MCF7 parental tumors (P = 0.23) 3 days after 17-DMAG treatment; optical imaging signal recovered in both tumor types at days 6 to 9. In the carrier group, no signal reduction was observed. Pearson correlation of in vivo optical imaging signal with ex vivo Her2 levels ranged from 0.73 to 0.89.Optical imaging with an affibody can be used to noninvasively monitor changes in Her2 expression in vivo as a response to treatment with an Hsp90 inhibitor, with results similar to response measurements in positron emission tomography imaging studies.

    View details for DOI 10.1158/1078-0432.CCR-10-3213

    View details for Web of Science ID 000300628100017

    View details for PubMedID 22235098

  • Proof-of-Concept Study of Monitoring Cancer Drug Therapy with Cerenkov Luminescence Imaging JOURNAL OF NUCLEAR MEDICINE Xu, Y., Chang, E., Liu, H., Jiang, H., Gambhir, S. S., Cheng, Z. 2012; 53 (2): 312-317

    Abstract

    Cerenkov luminescence imaging (CLI) has emerged as a less expensive, easier-to-use, and higher-throughput alternative to other nuclear imaging modalities such as PET. It is expected that CLI will find many applications in biomedical research such as cancer detection, probe development, drug screening, and therapy monitoring. In this study, we explored the possibility of using CLI to monitor drug efficacy by comparisons against PET. To assess the performance of both modalities in therapy monitoring, 2 murine tumor models (large cell lung cancer cell line H460 and prostate cancer cell line PC3) were given bevacizumab versus vehicle treatments. Two common radiotracers, 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) and (18)F-FDG, were used to monitor bevacizumab treatment efficacy.One group of mice (n = 6) was implanted with H460 xenografts bilaterally in the shoulder region, divided into treatment and control groups (n = 3 each), injected with (18)F-FLT, and imaged with PET immediately followed by CLI. The other group of mice (n = 6) was implanted with PC3 xenografts in the same locations, divided into treatment and control groups (n = 3 each), injected with (18)F-FDG, and imaged by the same modalities. Bevacizumab treatment was performed by 2 injections of 20 mg/kg at days 0 and 2.On (18)F-FLT scans, both CLI and PET revealed significantly decreased signals from H460 xenografts in treated mice from pretreatment to day 3. Moderately increased to unchanged signals were observed in untreated mice. On (18)F-FDG scans, both CLI and PET showed relatively unchanged signals from PC3 tumors in both treated and control groups. Quantifications of tumor signals of Cerenkov luminescence and PET images showed that the 2 modalities had excellent correlations (R(2) > 0.88 across all study groups).CLI and PET exhibit excellent correlations across different tumor xenografts and radiotracers. This is the first study, to our knowledge, demonstrating the use of CLI for monitoring cancer treatment. The findings warrant further exploration and optimization of CLI as an alternative to PET in preclinical therapeutic monitoring and drug screening.

    View details for DOI 10.2967/jnumed.111.094623

    View details for Web of Science ID 000300032800024

    View details for PubMedID 22241909

  • Evaluation of Four Affibody-Based Near-Infrared Fluorescent Probes for Optical Imaging of Epidermal Growth Factor Receptor Positive Tumors. Bioconjugate chemistry Qi, S., Miao, Z., Liu, H., Xu, Y., Feng, Y., Cheng, Z. 2012

    Abstract

    The epidermal growth factor receptor 1 (EGFR) has become an attractive target for cancer molecular imaging and therapy. An Affibody protein with strong binding affinity for EGFR, Z(EGFR:1907), has been reported. We are interested in translating Affibody molecules to potential clinical optical imaging of EGFR positive cancers. In this study, four anti-EGFR Affibody based near-infrared (NIR) fluorescent probes were thus prepared, and their in vivo performance was evaluated in the mice bearing EGFR positive subcutaneous A431 tumors. Methods: The Affibody analogue, Ac-Cys-Z(EGFR:1907), was synthesized using solid-phase peptide synthesis method. The purified small protein was then site-specifically conjugated with four NIR fluorescent dyes, Cy5.5-monomaleimide, Alex-Fluor-680-maleimide, SRfluor680-maleimide, or IRDye-800CW-maleimide, to produce four optical probes-Cy5.5-Z(EGFR:1907), Alexa680-Z(EGFR:1907), SR680-Z(EGFR:1907), and 800CW-Z(EGFR:1907). The EGFR binding property and specificity of the four NIR fluorescent Affibody probes were studied by fluorescence microscopy using high EGFR expressing A431 cells and low expressing MCF7 cells. The binding affinities of the probes (K(D)) to EGFR were further determined by flow cytometry. In vivo optical imaging of the four probes was performed in the mice bearing subcutaneous A431 tumors. Results: The four NIR optical probes were prepared in high purity. In vitro cell imaging studies demonstrated that all of them could specifically bind to EGFR positive A431 cells while showing minimum uptake in low EGFR expressing MCF7 cells. Flow cytometry showed that Cy5.5-Z(EGFR:1907) and Alexa680-Z(EGFR:1907) possessed high binding affinity in low nanomolar range (43.6 8.4 and 28.3 4.9, respectively). In vivo optical imaging of the four probes revealed that they all showed fast tumor targeting ability and good tumor-to-normal tissue contrast as early as 0.5 h postinjection (p.i.). The tumor-to-normal tissue ratio reached a peak at 2 to 4 h p.i. by regional of interest (ROI) analysis of images. Ex vivo studies further demonstrated that the four probes had high tumor uptakes. Particularly, Cy5.5-Z(EGFR:1907) and Alex680-Z(EGFR:1907) displayed higher tumor-to-normal tissue ratios than those of the other two probes. Conclusion: This work demonstrates that Affibody proteins can be modified with different NIR fluorescent dyes and used for imaging of EGFR expressing tumors. Different NIR fluorescent dyes have variable impact on the in vitro binding and in vivo performance of the resulting Affibody based probes. Therefore, selection of an appropriate NIRF label is important for optical probe development. The probes developed are promising for further tumor imaging applications and clinical translation. Particularly, Alex680-Z(EGFR:1907) and Cy5.5-Z(EGFR:1907) are excellent candidates as EGFR-targeted probes for optical imaging.

    View details for PubMedID 22621238

  • 111In-Labeled Agouti Related Proteins for SPECT/CT Imaging of Tumor &#945;v&#946;3 Integrin. Journal of Biomedicine and Biotechnology Jiang L, Miao Z, Kimura RH, Ren G, Liu HG, Silverman AP, Li PY, Gambhir SS, Cochran JR, Cheng Z. 2012; 2012: doi:10.1155/2012/ 36
  • Endoscopic Imaging of Cerenkov Luminescence Biomedical Optics Express Kothapalli Sri-R, Liu H, Liao JC, Cheng Z*, Gambhir SS*. 2012; 3: 1215-1225
  • Cerenkov Luminescence Imaging (CLI) for cancer therapy monitoring. Journal of visualized experiments : JoVE Xu, Y., Liu, H., Chang, E., Jiang, H., Cheng, Z. 2012: e4341-?

    Abstract

    In molecular imaging, positron emission tomography (PET) and optical imaging (OI) are two of the most important and thus most widely used modalities. PET is characterized by its excellent sensitivity and quantification ability while OI is notable for non-radiation, relative low cost, short scanning time, high throughput, and wide availability to basic researchers. However, both modalities have their shortcomings as well. PET suffers from poor spatial resolution and high cost, while OI is mostly limited to preclinical applications because of its limited tissue penetration along with prominent scattering optical signals through the thickness of living tissues. Recently a bridge between PET and OI has emerged with the discovery of Cerenkov Luminescence Imaging (CLI). CLI is a new imaging modality that harnesses Cerenkov Radiation (CR) to image radionuclides with OI instruments. Russian Nobel laureate Alekseyevich Cerenkov and his colleagues originally discovered CR in 1934. It is a form of electromagnetic radiation emitted when a charged particle travels at a superluminal speed in a dielectric medium. The charged particle, whether positron or electron, perturbs the electromagnetic field of the medium by displacing the electrons in its atoms. After passing of the disruption photons are emitted as the displaced electrons return to the ground state. For instance, one (18)F decay was estimated to produce an average of 3 photons in water. Since its emergence, CLI has been investigated for its use in a variety of preclinical applications including in vivo tumor imaging, reporter gene imaging, radiotracer development, multimodality imaging, among others. The most important reason why CLI has enjoyed much success so far is that this new technology takes advantage of the low cost and wide availability of OI to image radionuclides, which used to be imaged only by more expensive and less available nuclear imaging modalities such as PET. Here, we present the method of using CLI to monitor cancer drug therapy. Our group has recently investigated this new application and validated its feasibility by a proof-of-concept study. We demonstrated that CLI and PET exhibited excellent correlations across different tumor xenografts and imaging probes. This is consistent with the overarching principle of CR that CLI essentially visualizes the same radionuclides as PET. We selected Bevacizumab (Avastin; Genentech/Roche) as our therapeutic agent because it is a well-known angiogenesis inhibitor. Maturation of this technology in the near future can be envisioned to have a significant impact on preclinical drug development, screening, as well as therapy monitoring of patients receiving treatments.

    View details for DOI 10.3791/4341

    View details for PubMedID 23183774

  • A Novel StarPEG Platform for Bombesin Peptide Delivery to GRPR in Prostate Cancer ACS Macro Letters Xu Y, Huang W, Gang R, Qi S, Jiang H, Miao Z, Liu H, Lucente E, Barron A, Cheng Z 2012; 1: 753-757
  • In Vivo Biodistribution and Small Animal PET of (64)Cu-Labeled Antimicrobial Peptoids. Bioconjugate chemistry Seo, J., Ren, G., Liu, H., Miao, Z., Park, M., Wang, Y., Miller, T. M., Barron, A. E., Cheng, Z. 2012

    Abstract

    Peptoids are a rapidly developing class of biomimetic polymers based on oligo-N-substituted glycine backbones, designed to mimic peptides and proteins. Inspired by natural antimicrobial peptides, a group of cationic amphipathic peptoids has been successfully discovered with potent, broad-spectrum activity against pathogenic bacteria; however, there are limited studies to address the in vivo pharmacokinetics of the peptoids. Herein, (64)Cu-labeled DOTA conjugates of three different peptoids and two control peptides were synthesized and assayed in vivo by both biodistribution studies and small animal positron emission tomography (PET). The study was designed in a way to assess how structural differences of the peptidomimetics affect in vivo pharmacokinetics. As amphipathic molecules, major uptake of the peptoids occurred in the liver. Increased kidney uptake was observed by deleting one hydrophobic residue in the peptoid, and (64)Cu-3 achieved the highest kidney uptake of all the conjugates tested in this study. In comparison to peptides, our data indicated that peptoids had general in vivo properties of higher tissue accumulation, slower elimination, and higher in vivo stability. Different administration routes (intravenous, intraperitoneal, and oral) were investigated with peptoids. When administered orally, the peptoids showed poor bioavailability, reminiscent of that of peptide. However, remarkably longer passage through the gastrointestinal (GI) tract without rapid digestion was observed for peptoids. These unique in vivo properties of peptoids were rationalized by efficient cellular membrane permeability and protease resistance of peptoids. The results observed in the biodistribution studies could be confirmed by PET imaging, which provides a reliable way to evaluate in vivo pharmacokinetic properties of peptoids noninvasively and in real time. The pharmacokinetic data presented here can provide insight for further development of the antimicrobial peptoids as pharmaceuticals.

    View details for PubMedID 22486390

  • A Novel Clinically Translatable Fluorescent Nanoparticle for Targeted Molecular Imaging of Tumors in Living Subjects NANO LETTERS Gao, J., Chen, K., Luong, R., Bouley, D. M., Mao, H., Qiao, T., Gambhir, S. S., Cheng, Z. 2012; 12 (1): 281-286

    Abstract

    The use of quantum dots (QDs) in biomedical research has grown tremendously, yet successful examples of clinical applications are absent due to many clinical concerns. Here, we report on a new type of stable and biocompatible dendron-coated InP/ZnS core/shell QD as a clinically translatable nanoprobe for molecular imaging applications. The QDs (QD710-Dendron) were demonstrated to hold several significant features: near-infrared (NIR) emission, high stability in biological media, suitable size with possible renal clearance, and ability of extravasation. More importantly, a pilot mouse toxicity study confirmed that QD710-Dendron lacks significant toxicity at the doses tested. The acute tumor uptake of QD710-Dendron resulted in good contrast from the surrounding nontumorous tissues, indicating the possibility of passive targeting of the QDs. The highly specific targeting of QD710-Dendron-RGD(2) to integrin ?(v)?(3)-positive tumor cells resulted in high tumor uptake and long retention of the nanoprobe at tumor sites. In summary, QD710-Dendron and RGD-modified nanoparticles demonstrate small size, high stability, biocompatibility, favorable in vivo pharmacokinetics, and successful tumor imaging properties. These features satisfy the requirements for clinical translation and should promote efforts to further investigate the possibility of using QD710-Dendron-based nanoprobes in the clinical setting in the near future.

    View details for DOI 10.1021/nl203526f

    View details for Web of Science ID 000298943100049

    View details for PubMedID 22172022

  • Radioluminescent Nanophosphors Enable Multiplexed Small-Animal Imaging Optic Express Carpenter CM, Sun C, Pratx G, Liu H, Cheng Z, Xing L 2012; 20 (11): 11598-11604
  • A photonic crystal cavity-optical fiber tip nanoparticle sensor for biomedical applications Applied Physics Letters Shambat G, Kothapalli SR, Khurana A, Provine J, Sarmiento T, Cheng K, Cheng Z, Harris J, Daldrup-Link H, Gambhir SS, Vuckovi J. 2012; 100: 213702
  • Analysis of in situ and ex vivo alpha(V)beta(3) integrin expression during experimental carotid atherogenesis INTERNATIONAL JOURNAL OF NANOMEDICINE Yao, Y., Jiang, Y., Sheng, Z., Zhang, Y., An, Y., Yan, F., Ma, G., Liu, N., Teng, G., Cheng, Z. 2012; 7: 641-649

    Abstract

    Mural inflammation has been shown to contribute to the development of plaque, with the ?(V)?(3) integrin highly expressed in atherosclerotic plaques. We herein examined ?(V)?(3) integrin expression as a function of carotid atherosclerosis formation in the apolipoprotein E-deficient (apoE(-/-)) mouse.Constrictive collars were placed around the left common carotid arteries of apo E(-/-) mice maintained on a high-fat diet (n = 14). Before and 21 days following collar placement, in vivo serial magnetic resonance imaging (MRI) measurements of the carotid aortic diameter were performed using a 7T magnetic resonance (MR) scanner. Near- infrared fluorescence (NIRF) imaging was performed (n = 6) using an in vivo imaging system 0-24 hours following administration of 1.0 nmol c(RGDyK)-Cy5.5 via the tail vein. A competition experiment was performed by the co-injection of a saturating dose of bicyclic RGD peptide H-Glu[cyclo(Arg-Gly-Asp-D-Tyr-Lys)]2 (n = 3). Following image acquisition and sacrifice at 24 hours after injection, carotid arteries were harvested for histological analyses. Neointima formation and arterial remodeling in the carotid arteries of apoE(-/-) mice were induced by the placement of a constrictive collar. Significantly greater fluorescent signals were obtained from constrictive collar left common carotid arteries as compared to uninvolved aortic segments in constrictive collar mice. Binding to stenotic lesions was efficiently blocked in competition experiments. Immunostaining confirmed the presence of mural ?(V)?(3) integrin expression in macrophages in the neointima. Signal intensity increased in a macrophage density-dependent fashion in the stenotic segments.Mural ?(V)?(3) integrin expression, as determined using RGD-Cy5.5 near-infrared optical imaging, was increased in carotid arteries with constrictive collars in experimental mice. This expression can estimate the macrophage-bound inflammatory activity of atherosclerotic lesions.

    View details for DOI 10.2147/IJN.S28065

    View details for Web of Science ID 000302713100001

    View details for PubMedID 22334786

  • Harnessing the Power of Radionuclides for Optical Imaging: Cerenkov Luminescence Imaging JOURNAL OF NUCLEAR MEDICINE Xu, Y., Liu, H., Cheng, Z. 2011; 52 (12): 2009-2018

    Abstract

    Over the past several years, nuclear imaging modalities such as PET and SPECT have received much attention because they have been instrumental not only in preclinical cancer research but also in nuclear medicine. Yet nuclear imaging is limited by high instrumentation cost and subsequently low availability to basic researchers. Cerenkov radiation, a relativistic physical phenomenon that was discovered 70 years ago, has recently become an intriguing subject of study in molecular imaging because of its potential in augmenting nuclear imaging, particularly in preclinical small-animal studies. The intrinsic capability of radionuclides emitting luminescent light from decay is promising because of the possibility of bridging nuclear imaging with optical imaging-a modality that is much less expensive, is easier to use, and has higher throughput than its nuclear counterpart. Thus, with the maturation of this novel imaging technology using Cerenkov radiation, which is termed Cerenkov luminescence imaging, it is foreseeable that advances in both nuclear imaging and preclinical research involving radioisotopes will be significantly accelerated in the near future.

    View details for DOI 10.2967/jnumed.111.092965

    View details for Web of Science ID 000298162500039

    View details for PubMedID 22080446

  • Non-Invasive Imaging of Cysteine Cathepsin Activity in Solid Tumors Using a Cu-64-Labeled Activity-Based Probe PLOS ONE Ren, G., Blum, G., Verdoes, M., Liu, H., Syed, S., Edgington, L. E., Gheysens, O., Miao, Z., Jiang, H., Gambhir, S. S., Bogyo, M., Cheng, Z. 2011; 6 (11)

    Abstract

    The papain family of cysteine cathepsins are actively involved in multiple stages of tumorigenesis. Because elevated cathepsin activity can be found in many types of human cancers, they are promising biomarkers that can be used to target radiological contrast agents for tumor detection. However, currently there are no radiological imaging agents available for these important molecular targets. We report here the development of positron emission tomography (PET) radionuclide-labeled probes that target the cysteine cathepsins by formation of an enzyme activity-dependent bond with the active site cysteine. These probes contain an acyloxymethyl ketone (AOMK) functional group that irreversibly labels the active site cysteine of papain family proteases attached to a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) tag for labeling with (64)Cu for PET imaging studies. We performed biodistribution and microPET imaging studies in nude mice bearing subcutaneous tumors expressing various levels of cysteine cathepsin activity and found that the extent of probe uptake by tumors correlated with overall protease activity as measured by biochemical methods. Furthermore, probe signals could be reduced by pre-treatment with a general cathepsin inhibitor. We also found that inclusion of a Cy5 tag on the probe increased tumor uptake relative to probes lacking this fluorogenic dye. Overall, these results demonstrate that small molecule activity-based probes carrying radio-tracers can be used to image protease activity in living subjects.

    View details for DOI 10.1371/journal.pone.0028029

    View details for Web of Science ID 000297789900039

    View details for PubMedID 22132198

  • A novel F-18-labeled two-helix scaffold protein for PET imaging of HER2-positive tumor EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Miao, Z., Ren, G., Jiang, L., Liu, H., Webster, J. M., Zhang, R., Namavari, M., Gambhir, S. S., Syud, F., Cheng, Z. 2011; 38 (11): 1977-1984

    Abstract

    Two-helix scaffold proteins (~ 5 kDa) against human epidermal growth factor receptor type 2 (HER2) have been discovered in our previous work. In this research we aimed to develop an (18)F-labeled two-helix scaffold protein for positron emission tomography (PET) imaging of HER2-positive tumors.An aminooxy-functionalized two-helix peptide (AO-MUT-DS) with high HER2 binding affinity was synthesized through conventional solid phase peptide synthesis. The purified linear peptide was cyclized by I(2) oxidation to form a disulfide bridge. The cyclic peptide was then conjugated with a radiofluorination synthon, 4-(18)F-fluorobenzyl aldehyde ((18)F-FBA), through the aminooxy functional group at the peptide N terminus (30% yield, non-decay corrected). The binding affinities of the peptides were analyzed by Biacore analysis. Cell uptake assay of the resulting PET probe, (18)F-FBO-MUT-DS, was performed at 37C. (18)F-FBO-MUT-DS with high specific activity (20-32 MBq/nmol, 88-140 ?Ci/?g, end of synthesis) was injected into mice xenograft model bearing SKOV3 tumor. MicroPET and biodistribution and metabolic stability studies were then conducted.Cell uptake assays showed high and specific cell uptake (~12% applied activity at 1 h) by incubation of (18)F-FBO-MUT-DS with HER2 high-expressing SKOV3 ovarian cancer cells. The affinities (K(D)) of AO-MUT-DS and FBO-MUT-DS as tested by Biacore analysis were 2 and 1 nM, respectively. In vivo small animal PET demonstrated fast tumor targeting, high tumor accumulation, and good tumor to normal tissue contrast of (18)F-FBO-MUT-DS. Biodistribution studies further revealed that the probe had excellent tumor uptake (6.9%ID/g at 1 h post-injection) and was cleared through both liver and kidneys. Co-injection of the probe with 500 ?g of HER2 Affibody protein reduced the tumor uptake (6.9 vs 1.8%ID/g, p < 0.05).F-FBO-MUT-DS displays excellent HER2 targeting ability and tumor PET imaging quality. The two-helix scaffold proteins are suitable for development of (18)F-based PET probes.

    View details for DOI 10.1007/s00259-011-1879-9

    View details for Web of Science ID 000295680200004

    View details for PubMedID 21761266

  • Protein scaffold-based molecular probes for cancer molecular imaging AMINO ACIDS Miao, Z., Levi, J., Cheng, Z. 2011; 41 (5): 1037-1047

    Abstract

    Protein scaffold molecules are powerful reagents for targeting various cell signal receptors, enzymes, cytokines and other cancer-related molecules. They belong to the peptide and small protein platform with distinct properties. For the purpose of development of new generation molecular probes, various protein scaffold molecules have been labeled with imaging moieties and evaluated both in vitro and in vivo. Among the evaluated probes Affibody molecules and analogs, cystine knot peptides, and nanobodies have shown especially good characteristics as protein scaffold platforms for development of in vivo molecular probes. Quantitative data obtained from positron emission tomography, single photon emission computed tomography/CT, and optical imaging together with biodistribution studies have shown high tumor uptakes and high tumor-to-blood ratios for these probes. High tumor contrast imaging has been obtained within 1 h after injection. The success of those molecular probes demonstrates the adequacy of protein scaffold strategy as a general approach in molecular probe development.

    View details for DOI 10.1007/s00726-010-0503-9

    View details for Web of Science ID 000296469100003

    View details for PubMedID 20174842

  • Adipose tissue-derived stem cells display a proangiogenic phenotype on 3D scaffolds. Journal of biomedical materials research. Part A Neofytou, E. A., Chang, E., Patlola, B., Joubert, L., Rajadas, J., Gambhir, S. S., Cheng, Z., Robbins, R. C., Beygui, R. E. 2011; 98 (3): 383-393

    Abstract

    Ischemic heart disease is the leading cause of death worldwide. Recent studies suggest that adipose tissue-derived stem cells (ASCs) can be used as a potential source for cardiovascular tissue engineering due to their ability to differentiate along the cardiovascular lineage and to adopt a proangiogenic phenotype. To understand better ASCs' biology, we used a novel 3D culture device. ASCs' and b.END-3 endothelial cell proliferation, migration, and vessel morphogenesis were significantly enhanced compared to 2D culturing techniques. ASCs were isolated from inguinal fat pads of 6-week-old GFP+/BLI+ mice. Early passage ASCs cells (P3-P4), PKH26-labeled murine b.END-3 cells or a co-culture of ASCs and b.END-3 cells were seeded at a density of 1 10(5) on three different surface configurations: (a) a 2D surface of tissue culture plastic, (b) Matrigel, and (c) a highly porous 3D scaffold fabricated from inert polystyrene. VEGF expression, cell proliferation, and tubulization, were assessed using optical microscopy, fluorescence microscopy, 3D confocal microscopy, and SEM imaging (n = 6). Increased VEGF levels were seen in conditioned media harvested from co-cultures of ASCs and b.END-3 on either Matrigel or a 3D matrix. Fluorescence, confocal, SEM, bioluminescence revealed improved cell, proliferation, and tubule formation for cells seeded on the 3D polystyrene matrix. Collectively, these data demonstrate that co-culturing ASCs with endothelial cells in a 3D matrix environment enable us to generate prevascularized tissue-engineered constructs. This can potentially help us to surpass the tissue thickness limitations faced by the tissue engineering community today.

    View details for DOI 10.1002/jbm.a.33113

    View details for PubMedID 21630430

  • One-step radiosynthesis of F-18-AlF-NOTA-RGD(2) for tumor angiogenesis PET imaging EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Liu, S., Liu, H., Jiang, H., Xu, Y., Zhang, H., Cheng, Z. 2011; 38 (9): 1732-1741

    Abstract

    One of the major obstacles of the clinical translation of (18)F-labeled arginine-glycine-aspartic acid (RGD) peptides has been the laborious multistep radiosynthesis. In order to facilitate the application of RGD-based positron emission tomography (PET) probes in the clinical setting we investigated in this study the feasibility of using the chelation reaction between Al(18)F and a macrocyclic chelator-conjugated dimeric RGD peptide as a simple one-step (18)F labeling strategy for development of a PET probe for tumor angiogenesis imaging.Dimeric cyclic peptide E[c(RGDyK)](2) (RGD(2)) was first conjugated with a macrocyclic chelator, 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA), and the resulting bioconjugate NOTA-RGD(2) was then radiofluorinated via Al(18)F intermediate to synthesize (18)F-AlF-NOTA-RGD(2). Integrin binding affinities of the peptides were assessed by a U87MG cell-based receptor binding assay using (125)I-echistatin as the radioligand. The tumor targeting efficacy and in vivo profile of (18)F-AlF-NOTA-RGD(2) were further evaluated in a subcutaneous U87MG glioblastoma xenograft model by microPET and biodistribution.NOTA-RGD(2) was successfully (18)F-fluorinated with good yield within 40 min using the Al(18)F intermediate. The IC(50) of (19)F-AlF-NOTA-RGD(2) was determined to be 46 4.4 nM. Quantitative microPET studies demonstrated that (18)F-AlF-NOTA-RGD(2) showed high tumor uptake, fast clearance from the body, and good tumor to normal organ ratios.NOTA-RGD(2) bioconjugate has been successfully prepared and labeled with Al(18)F in one single step of radiosynthesis. The favorable in vivo performance and the short radiosynthetic route of (18)F-AlF-NOTA-RGD(2) warrant further optimization of the probe and the radiofluorination strategy to accelerate the clinical translation of (18)F-labeled RGD peptides.

    View details for DOI 10.1007/s00259-011-1847-4

    View details for Web of Science ID 000293637900017

    View details for PubMedID 21617974

  • Preclinical Evaluation of Raman Nanoparticle Biodistribution for their Potential Use in Clinical Endoscopy Imaging SMALL Zavaleta, C. L., Hartman, K. B., Miao, Z., James, M. L., Kempen, P., Thakor, A. S., Nielsen, C. H., Sinclair, R., Cheng, Z., Gambhir, S. S. 2011; 7 (15): 2232-2240

    Abstract

    Raman imaging offers unsurpassed sensitivity and multiplexing capabilities. However, its limited depth of light penetration makes direct clinical translation challenging. Therefore, a more suitable way to harness its attributes in a clinical setting would be to couple Raman spectroscopy with endoscopy. The use of an accessory Raman endoscope in conjunction with topically administered tumor-targeting Raman nanoparticles during a routine colonoscopy could offer a new way to sensitively detect dysplastic lesions while circumventing Raman's limited depth of penetration and avoiding systemic toxicity. In this study, the natural biodistribution of gold surface-enhanced Raman scattering (SERS) nanoparticles is evaluated by radiolabeling them with (64) Cu and imaging their localization over time using micropositron emission tomography (PET). Mice are injected either intravenously (IV) or intrarectally (IR) with approximately 100 microcuries (?Ci) (3.7 megabecquerel (MBq)) of (64) Cu-SERS nanoparticles and imaged with microPET at various time points post injection. Quantitative biodistribution data are obtained as % injected dose per gram (%ID g(-1)) from each organ, and the results correlate well with the corresponding microPET images, revealing that IV-injected mice have significantly higher uptake (p < 0.05) in the liver (5 h = 8.96% ID g(-1); 24 h = 8.27% ID g(-1)) than IR-injected mice (5 h = 0.09% ID g(-1); 24 h = 0.08% ID g(-1)). IR-injected mice show localized uptake in the large intestine (5 h = 10.37% ID g(-1); 24 h = 0.42% ID g(-1)) with minimal uptake in other organs. Raman imaging of excised tissues correlate well with biodistribution data. These results suggest that the topical application of SERS nanoparticles in the mouse colon appears to minimize their systemic distribution, thus avoiding potential toxicity and supporting the clinical translation of Raman spectroscopy as an endoscopic imaging tool.

    View details for DOI 10.1002/smll.201002317

    View details for Web of Science ID 000294361200015

    View details for PubMedID 21608124

  • Synthesis and Radioluminescence of PEGylated Eu3+-doped Nanophosphors as Bioimaging Probes ADVANCED MATERIALS Sun, C., Pratx, G., Carpenter, C. M., Liu, H., Cheng, Z., Gambhir, S. S., Xing, L. 2011; 23 (24): H195-H199

    View details for DOI 10.1002/adma.201100919

    View details for Web of Science ID 000293046600018

    View details for PubMedID 21557339

  • Enzyme-Responsive Multifunctional Magnetic Nanoparticles for Tumor Intracellular Drug Delivery and Imaging CHEMISTRY-AN ASIAN JOURNAL Yang, Y., Aw, J., Chen, K., Liu, F., Padmanabhan, P., Hou, Y., Cheng, Z., Xing, B. 2011; 6 (6): 1381-1389

    Abstract

    Enzyme-responsive, hybrid, magnetic silica nanoparticles have been employed for multifunctional applications in selective drug delivery and intracellular tumor imaging. In this study, doxorubicin (Dox)-conjugated, enzyme-cleavable peptide precursors were covalently tethered onto the surface of uniform silica-coated magnetic nanoparticles through click chemistry. This enzyme-responsive nanoparticle conjugate demonstrated highly efficient Dox release upon specific enzyme interactions in vitro. It also exhibits multiple functions in selective tumor intracellular drug delivery and imaging in the tumor cells with high cathepsin B expression, whereas it exhibited lower cytotoxicity towards other cells without enzyme expression.

    View details for DOI 10.1002/asia.201000905

    View details for Web of Science ID 000292097700015

    View details for PubMedID 21548100

  • Macrocyclic chelator assembled RGD multimers for tumor targeting BIOORGANIC & MEDICINAL CHEMISTRY LETTERS Zhang, X., Liu, H., Miao, Z., Kimura, R., Fan, F., Cheng, Z. 2011; 21 (11): 3423-3426

    Abstract

    Macrocyclic chelators have been extensively used for complexation of metal ions. A widely used chelator, DOTA, has been explored as a molecular platform to assemble multiple bioactive peptides in this paper. The multivalent DOTA-peptide bioconjugates demonstrate promising tumor targeting ability.

    View details for DOI 10.1016/j.bmcl.2011.03.110

    View details for Web of Science ID 000290708300049

    View details for PubMedID 21524578

  • In vivo imaging of embryonic stem cell therapy EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Jiang, H., Cheng, Z., Tian, M., Zhang, H. 2011; 38 (4): 774-784

    Abstract

    Embryonic stem cells (ESCs) have the most pluripotent potential of any stem cell. These cells, isolated from the inner cell mass of the blastocyst, are "pluripotent," meaning that they can give rise to all cell types within the developing embryo. As a result, ESCs have been regarded as a leading candidate source for novel regenerative medicine therapies and have been used to derive diverse cell populations, including myocardial and endothelial cells. However, before they can be safely applied clinically, it is important to understand the in vivo behavior of ESCs and their derivatives. In vivo analysis of ESC-derived cells remains critically important to define how these cells may function in novel regenerative medicine therapies. In this review, we describe several available imaging modalities for assessing cell engraftment and discuss their strengths and limitations. We also analyze the applications of these modalities in assessing the utility of ESCs in regenerative medicine therapies.

    View details for DOI 10.1007/s00259-010-1667-y

    View details for Web of Science ID 000288255500020

    View details for PubMedID 21107558

  • Preliminary evaluation of Lu-177-labeled knottin peptides for integrin receptor-targeted radionuclide therapy EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Jiang, L., Miao, Z., Kimura, R. H., Liu, H., Cochran, J. R., Culter, C. S., Bao, A., Li, P., Cheng, Z. 2011; 38 (4): 613-622

    Abstract

    Cystine knot peptides (knottins) 2.5D and 2.5F were recently engineered to bind integrin receptors with high affinity and specificity. These receptors are overexpressed on the surface of a variety of malignant human tumor cells and tumor neovasculature. In this study, 2.5D and 2.5F were labeled with a therapeutic radionuclide, (177)Lu, and the resulting radiopeptides were then evaluated as potential radiotherapeutic agents in a murine model of human glioma xenografts.Knottins 2.5D and 2.5F were synthesized using solid phase peptide synthesis, folded in vitro, and site-specifically coupled with 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) at their N terminus for (177)Lu radiolabeling. The stability of the radiopeptides (177)Lu-DOTA-2.5D and (177)Lu-DOTA-2.5F was tested in both phosphate-buffered saline (PBS) and mouse serum. Cell uptake assays of the radiolabeled peptides were performed in U87MG integrin-expressing human glioma cells. The biodistribution studies of both (177)Lu-DOTA-2.5D and (177)Lu-DOTA-2.5F were examined in U87MG tumor-bearing athymic nu/nu mice. Radiation absorbed doses for the major tissues of a human adult male were calculated based on the mouse biodistribution results.DOTA-2.5D and DOTA-2.5F were labeled with (177)Lu at over 55% efficiency. High radiochemical purity for both radiocomplexes (> 95%) could be achieved after high performance liquid chromatography (HPLC) purification. Both radiopeptides were stable in PBS and mouse serum. Compared to (177)Lu-DOTA-2.5D (0.39 and 0.26 %ID/g at 2 and 24h, respectively), (177)Lu-DOTA-2.5F showed much higher tumor uptake (2.16 and 0.78 %ID/g at 2 and 24h, respectively). It also displayed higher tumor to blood ratios than that of (177)Lu-DOTA-2.5D (31.8 vs 18.7 at 24h and 52.6 vs 20.6 at 72h). Calculation of radiodosimetry for (177)Lu-DOTA-2.5D and (177)Lu-DOTA-2.5F suggested that tumor and kidney were tissues with the highest radiation absorbed doses. Moreover, (177)Lu-DOTA-2.5F had a higher tumor to kidney radiation absorbed dose ratio than that of (177)Lu-DOTA-2.5D.Cystine knot peptides can be successfully radiolabeled with (177)Lu for potential therapeutic applications. Knottin 2.5F labeled with (177)Lu exhibits favorable distribution in murine U87MG xenograft model; thus, it is a promising agent for radionuclide therapy of integrin-positive tumors.

    View details for DOI 10.1007/s00259-010-1684-x

    View details for Web of Science ID 000288255500002

    View details for PubMedID 21153409

  • Reproducibility study of [F-18]FPP(RGD)(2) uptake in murine models of human tumor xenografts EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Chang, E., Liu, S., Gowrishankar, G., Yaghoubi, S., Wedgeworth, J. P., Chin, F., Berndorff, D., Gekeler, V., Gambhir, S. S., Cheng, Z. 2011; 38 (4): 722-730

    Abstract

    An (18)F-labeled PEGylated arginine-glycine-aspartic acid (RGD) dimer {[(18)F]FPP(RGD)(2)} has been used to image tumor ?(v)?(3) integrin levels in preclinical and clinical studies. Serial positron emission tomography (PET) studies may be useful for monitoring antiangiogenic therapy response or for drug screening; however, the reproducibility of serial scans has not been determined for this PET probe. The purpose of this study was to determine the reproducibility of the integrin ?(v)?(3)-targeted PET probe, [(18)F]FPP(RGD)(2,) using small animal PET.Human HCT116 colon cancer xenografts were implanted into nude mice (n?=?12) in the breast and scapular region and grown to mean diameters of 5-15mm for approximately 2.5weeks. A 3-min acquisition was performed on a small animal PET scanner approximately 1h after administration of [(18)F]FPP(RGD)(2) (1.9-3.8MBq, 50-100?Ci) via the tail vein. A second small animal PET scan was performed approximately 6h later after reinjection of the probe to assess for reproducibility. Images were analyzed by drawing an ellipsoidal region of interest (ROI) around the tumor xenograft activity. Percentage injected dose per gram (%ID/g) values were calculated from the mean or maximum activity in the ROIs. Coefficients of variation and differences in %ID/g values between studies from the same day were calculated to determine the reproducibility.The coefficient of variation (meanSD) for %ID(mean)/g and %ID(max)/g values between [(18)F]FPP(RGD)(2) small animal PET scans performed 6h apart on the same day were 11.1??7.6% and 10.4??9.3%, respectively. The corresponding differences in %ID(mean)/g and %ID(max)/g values between scans were -0.025??0.067 and -0.039??0.426. Immunofluorescence studies revealed a direct relationship between extent of ?(?)?(3) integrin expression in tumors and tumor vasculature with level of tracer uptake. Mouse body weight, injected dose, and fasting state did not contribute to the variability of the scans; however, consistent scanning parameters were necessary to ensure accurate studies, in particular, noting tumor volume, as well as making uniform: the time of imaging after injection and the ROI size. Reanalysis of ROI placement displayed variability for %ID(mean)/g of 6.6??3.9% and 0.28??0.12% for %ID(max)/g.[(18)F]FPP(RGD)(2) small animal PET mouse tumor xenograft studies are reproducible with relatively low variability.

    View details for DOI 10.1007/s00259-010-1672-1

    View details for Web of Science ID 000288255500015

    View details for PubMedID 21125268

  • Affibody-Functionalized Gold-Silica Nanoparticles for Raman Molecular Imaging of the Epidermal Growth Factor Receptor SMALL Jokerst, J. V., Miao, Z., Zavaleta, C., Cheng, Z., Gambhir, S. S. 2011; 7 (5): 625-633

    Abstract

    The affibody functionalization of fluorescent surface-enhanced Raman scattering gold-silica nanoparticles as multimodal contrast agents for molecular imaging specific to epidermal growth factor receptor (EGFR) is reported. This nanoparticle bioconjugate reports EGFR-positive A431 tumors with a signal nearly 35-fold higher than EGFR-negative MDA-435S tumors. The low-level EGFR expression in adjacent healthy tissue is 7-fold lower than in the positive tumors. Validation via competitive inhibition reduces the signal by a factor of six, and independent measurement of EGFR via flow cytometry correlates at R(2) = 0.92.

    View details for DOI 10.1002/smll.201002291

    View details for Web of Science ID 000288081900013

    View details for PubMedID 21302357

  • Affibody-based nanoprobes for HER2-expressing cell and tumor imaging BIOMATERIALS Gao, J., Chen, K., Miao, Z., Ren, G., Chen, X., Gambhir, S. S., Cheng, Z. 2011; 32 (8): 2141-2148

    Abstract

    This article reports the affibody-based nanoprobes specifically target and image human epidermal growth factor receptor type 2 (HER2)-expressing cells and tumors. The affibody molecules are a promising class of targeting ligands with simple, robust, and precise structure and high affinity. Using near-infrared (NIR) quantum dots (QDs) and iron oxide (IO) nanoparticles as two representative nanomaterials, we designed anti-HER2 affibody molecules with a N-terminus cysteine residue (Cysteine-Z(HER2:342)) and precisely conjugated with maleimide-functionalized nanoparticles to make nanoparticle-affibody conjugates. The in vitro and in vivo study showed the conjugates are highly specific to target and image HER2-expressing cells and tumors. This work indicated the nanoparticle-affibody conjugates may be excellent candidates as targeting probes for molecular imaging and diagnosis.

    View details for DOI 10.1016/j.biomaterials.2010.11.053

    View details for Web of Science ID 000287061400015

    View details for PubMedID 21147502

  • Radio labeled Affibody-Albumin Bioconjugates for HER2-Positive Cancer Targeting BIOCONJUGATE CHEMISTRY Hoppmann, S., Miao, Z., Liu, S., Liu, H., Ren, G., Bao, A., Cheng, Z. 2011; 22 (3): 413-421

    Abstract

    Affibody molecules have received significant attention in the fields of molecular imaging and drug development. However, Affibody scaffolds display an extremely high renal uptake, especially when modified with chelators and then labeled with radiometals. This unfavorable property may impact their use as radiotherapeutic agents in general and as imaging probes for the detection of tumors adjacent to kidneys in particular. Herein, we present a simple and generalizable strategy for reducing the renal uptake of Affibody molecules while maintaining their tumor uptake. Human serum albumin (HSA) was consecutively modified by 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid mono-N-hydroxysuccinimide ester (DOTA-NHS ester) and the bifunctional cross-linker sulfosuccinimidyl 4-[N-maleimidomethyl]cyclohexane-1-carboxylate (Sulfo-SMCC). The HER2 Affibody analogue, Ac-Cys-Z(HER2:342), was covalently conjugated with HSA, and the resulting bioconjugate DOTA-HSA-Z(HER2:342) was further radiolabeled with ??Cu and In and evaluated in vitro and in vivo. Radiolabeled DOTA-HSA-Z(HER2:342) conjugates displayed a significant and specific cell uptake into SKOV3 cell cultures. Positron emission tomography (PET) investigations using ??Cu-DOTA-HSA-Z(HER2:342) were performed in SKOV3 tumor-bearing nude mice. High tumor uptake values (>14% ID/g at 24 and 48 h) and high liver accumulations but low kidney accumulations were observed. Biodistribution studies and single-photon emission computed tomography (SPECT) investigations using In-DOTA-HSA-Z(HER2:342) validated these results. At 24 h post injection, the biodistribution data revealed high tumor (16.26% ID/g) and liver (14.11% ID/g) uptake but relatively low kidney uptake (6.06% ID/g). Blocking studies with coinjected, nonlabeled Ac-Cys-Z(HER2:342) confirmed the in vivo specificity of HER2. Radiolabeled DOTA-HSA-Z(HER2:342) Affibody conjugates are promising SPECT and PET-type probes for the imaging of HER2 positive cancer. More importantly, DOTA-HSA-Z(HER2:342) is suitable for labeling with therapeutic radionuclides (e.g., ??Y or ??Lu) for treatment studies. The approach of using HSA to optimize the pharmacokinetics and biodistribution profile of Affibodies may be extended to the design of many other targeting molecules.

    View details for DOI 10.1021/bc100432h

    View details for Web of Science ID 000288401400013

    View details for PubMedID 21299201

  • Functional Mutation of Multiple Solvent-Exposed Loops in the Ecballium elaterium Trypsin Inhibitor-II Cystine Knot Miniprotein PLOS ONE Kimura, R. H., Jones, D. S., Jiang, L., Miao, Z., Cheng, Z., Cochran, J. R. 2011; 6 (2)

    Abstract

    The Ecballium elaterium trypsin inhibitor (EETI-II), a 28-amino acid member of the knottin family of peptides, contains three interwoven disulfide bonds that form multiple solvent-exposed loops. Previously, the trypsin binding loop of EETI-II has been engineered to confer binding to several alternative molecular targets. Here, EETI-II was further explored as a molecular scaffold for polypeptide engineering by evaluating the ability to mutate two of its structurally adjacent loops.Yeast surface display was used to engineer an EETI-II mutant containing two separate integrin binding epitopes. The resulting knottin peptide was comprised of 38 amino acids, and contained 11- and 10-residue loops compared to wild-type EETI-II, which naturally contains 6- and 5-residue loops, respectively. This knottin peptide bound to ?(v)?(3) and ?(v)?(5) integrins with affinities in the low nanomolar range, but bound weakly to the related integrins ?(5)?(1) and ?(iib)?(3). In addition, the engineered knottin peptide inhibited tumor cell adhesion to vitronectin, an extracellular matrix protein that binds to ?(v)?(3) and ?(v)?(5) integrins. A (64)Cu radiolabeled version of this knottin peptide demonstrated moderate serum stability and excellent tumor-to-muscle and tumor-to-blood ratios by positron emission tomography imaging in human tumor xenograft models. Tumor uptake was ?3-5% injected dose per gram (%ID/g) at one hour post injection, with rapid clearance of probe through the kidneys.We demonstrated that multiple loops of EETI-II can be mutated to bind with high affinity to tumor-associated integrin receptors. The resulting knottin peptide contained 21 (>50%) non-native amino acids within two mutated loops, indicating that extended loop lengths and sequence diversity were well tolerated within the EETI-II scaffold. A radiolabeled version of this knottin peptide showed promise for non-invasive imaging of integrin expression in living subjects. However, reduced serum and metabolic stability were observed compared to an engineered integrin-binding EETI-II knottin peptide containing only one mutated loop.

    View details for DOI 10.1371/journal.pone.0016112

    View details for Web of Science ID 000287482800005

    View details for PubMedID 21364742

  • Ferritin Enhances SPIO Tracking of C6 Rat Glioma Cells by MRI MOLECULAR IMAGING AND BIOLOGY Wang, J., Xie, J., Zhou, X., Cheng, Z., Gu, N., Teng, G., Hu, Q., Zhu, F., Chang, S., Zhang, F., Lu, G., Chen, X. 2011; 13 (1): 87-93

    Abstract

    To investigate the effect of ferritin protein overexpression on superparamagnetic iron oxide (SPIO) particle labeling of C6 rat glioma cells, and track the labeled cells in vivo using magnetic resonance imaging (MRI).A plasmid of H-chain of murine ferritin gene was constructed and transfected into C6 cells. The parental and the transfected C6 cells labeled with SPIO were bilaterally inoculated subcutaneously into nude mice. The mice were imaged by multiple T2-weighted MR scans after C6 cell inoculation. The mice were killed 2 weeks later, and the concentration of iron in the tumor tissue was measured by inductively coupled plasma.The iron concentration in xenografts derived from SPIO-labeled C6 cells that were transfected with ferritin plasmid was significantly higher than that in xenografts from parental C6 cells that were labeled with SPIO but not transfected (p = 0.034, N = 5). Ferritin-transfected C6 cells showed an improved T(2) contrast in vivo compared with parental cells labeled with SPIO but not transfected.Coordinating ferritin with SPIO can lead to a longer MRI cellular tracking period.

    View details for DOI 10.1007/s11307-010-0338-5

    View details for Web of Science ID 000286395600012

    View details for PubMedID 20440566

  • PET Imaging of Integrin Positive Tumors Using F-18 Labeled Knottin Peptides THERANOSTICS Liu, S., Liu, H., Ren, G., Kimura, R. H., Cochran, J. R., Cheng, Z. 2011; 1: 403-412

    Abstract

    Purpose: Cystine knot (knottin) peptides, engineered to bind with high affinity to integrin receptors, have shown promise as molecular imaging agents in living subjects. The aim of the current study was to evaluate tumor uptake and in vivo biodistribution of (18)F-labeled knottins in a U87MG glioblastoma model.Procedures: Engineered knottin mutants 2.5D and 2.5F were synthesized using solid phase peptide synthesis and were folded in vitro, followed by radiolabeling with 4-nitrophenyl 2-(18)F-fluoropropionate ((18)F-NFP). The resulting probes, (18)F-FP-2.5D and (18)F-FP-2.5F, were evaluated in nude mice bearing U87MG tumor xenografts using microPET and biodistribution studies.Results: MicroPET imaging studies with (18)F-FP-2.5D and (18)F-FP-2.5F demonstrated high tumor uptake in U87MG xenograft mouse models. The probes exhibited rapid clearance from the blood and kidneys, thus leading to excellent tumor-to-normal tissue contrast. Specificity studies confirmed that (18)F-FP-2.5D and (18)F-FP-2.5F had reduced tumor uptake when co-injected with a large excess of the peptidomimetic c(RGDyK) as a blocking agent.Conclusions: (18)F-FP-2.5D and (18)F-FP-2.5F showed reduced gallbladder uptake compared with previously published (18)F-FB-2.5D. (18)F-FP-2.5D and (18)F-FP-2.5F enabled integrin-specific PET imaging of U87MG tumors with good imaging contrasts. (18)F-FP-2.5D demonstrated more desirable pharmacokinetics compared to (18)F-FP-2.5F, and thus has greater potential for clinical translation.

    View details for DOI 10.7150/thno/v01p0403

    View details for Web of Science ID 000299121000034

    View details for PubMedID 22211146

  • Recent Progress in Radiofluorination of Peptides for PET Molecular Imaging Current Organic Synthesis Liu S, S. C. 2011; 8 (4): 584-592
  • Molecular Probes for Bioluminescence Imaging Current Organic Synthesis Wu S, C. C. 2011; 8 (4): 488-497
  • Radiofluorinated Rhenium Cyclized alpha-MSH Analogues for PET Imaging of Melanocortin Receptor 1 BIOCONJUGATE CHEMISTRY Ren, G., Liu, S., Liu, H., Miao, Z., Cheng, Z. 2010; 21 (12): 2355-2360

    Abstract

    In order to accomplish in vivo molecular imaging of melanoma biomarker melanocortin 1 receptor (MC1R), several ?-melanocyte-stimulating hormone (?-MSH) analogues have been labeled with N-succinimidyl-4-?F-fluorobenzoate (?)F-SFB) and studied as positron emission tomography (PET) probes in our recent studies. To further pursue a radiofluorinated ?-MSH peptide with high clinical translation potential, we utilized 4-nitrophenyl 2-?F-fluoropropionate (?F-NFP) to radiofluorinate the transition metal rhenium cyclized ?-MSH metallopeptides for PET imaging of MC1R positive malignant melanoma. Metallopeptides Ac-d,Lys-ReCCMSH(Arg) (two isomers, namely RMSH-1 and RMSH-2) were synthesized using conventional solid phase peptide synthesis chemistry and rhenium cyclization reaction. The two isomers were then conjugated with ?F-NFP or ?F-NFP. The resulting cold or radiofluorinated metallopeptides, (?/?)F-FP-RMSH-1 and (?/?)F-FP-RMSH-2, were further evaluated for their in vitro receptor binding affinities, in vivo biodistribution, and small-animal PET imaging properties. The binding affinities of ?F-FP-RMSH-1 and ?F-FP-RMSH-2 were determined to be within low nanomolar range. In vivo studies revealed that both F-labeled metallopeptides possessed good tumor uptake in the B16F10 murine model with high MC1R expression, while possessing much lower uptake in A375M human melanoma xenografts. Moreover, ?F-FP-RMSH-1 displayed more favorable in vivo performance in terms of higher tumor uptake and much lower accumulation in the kidney and liver, when compared to that of ?F-FP-RMSH-2 at 2 h postinjection (p.i.). ?F-FP-RMSH-1 also displayed lower liver and lung uptake when compared with that of the same peptide labeled with ?F-SFB (named as ?F-FB-RMSH-1). Small animal PET imaging of ?F-FP-RMSH-1 in mice bearing B16F10 tumors at 1 and 2 h showed good tumor imaging quality. As expected, much lower tumor uptake and poorer tumor/normal organ contrast were observed for A375M model compared to those of the B16F10 model. ?F-FP-RMSH-1 also exhibited higher tumor uptake and better tumor retention when compared with ?F-FB-RMSH-1. ?F-FP-RMSH-1 demonstrates significant advantages over ?F-FB-RMSH-1 and ?F-FP-RMSH-2. It is a promising PET probe for imaging MC1R positive melanoma and MC1R expression in vivo.

    View details for DOI 10.1021/bc100391a

    View details for Web of Science ID 000285236300029

    View details for PubMedID 21073170

  • Effects of Nanoparticle Size on Cellular Uptake and Liver MRI with Polyvinylpyrrolidone-Coated Iron Oxide Nanoparticles ACS NANO Huang, J., Bu, L., Xie, J., Chen, K., Cheng, Z., Li, X., Chen, X. 2010; 4 (12): 7151-7160

    Abstract

    The effect of nanoparticle size (30-120 nm) on magnetic resonance imaging (MRI) of hepatic lesions in vivo has been systematically examined using polyvinylpyrrolidone (PVP)-coated iron oxide nanoparticles (PVP-IOs). Such biocompatible PVP-IOs with different sizes were synthesized by a simple one-pot pyrolysis method. These PVP-IOs exhibited good crystallinity and high T(2) relaxivities, and the relaxivity increased with the size of the magnetic nanoparticles. It was found that cellular uptake changed with both size and surface physiochemical properties, and that PVP-IO-37 with a core size of 37 nm and hydrodynamic particle size of 100 nm exhibited higher cellular uptake rate and greater distribution than other PVP-IOs and Feridex. We systematically investigated the effect of nanoparticle size on MRI of normal liver and hepatic lesions in vivo. The physical and chemical properties of the nanoparticles influenced their pharmacokinetic behavior, which ultimately determined their ability to accumulate in the liver. The contrast enhancement of PVP-IOs within the liver was highly dependent on the overall size of the nanoparticles, and the 100 nm PVP-IO-37 nanoparticles exhibited the greatest enhancement. These results will have implications in designing engineered nanoparticles that are optimized as MR contrast agents or for use in therapeutics.

    View details for DOI 10.1021/nn101643u

    View details for Web of Science ID 000285449100015

    View details for PubMedID 21043459

  • Near-infrared fluorescent nanoprobes for cancer molecular imaging: status and challenges TRENDS IN MOLECULAR MEDICINE He, X., Gao, J., Gambhir, S. S., Cheng, Z. 2010; 16 (12): 574-583

    Abstract

    Near-infrared fluorescence (NIRF) imaging promises to improve cancer imaging and management; advances in nanomaterials allow scientists to combine new nanoparticles with NIRF imaging techniques, thereby fulfilling this promise. Here, we present a synopsis of current developments in NIRF nanoprobes, their use in imaging small living subjects, their pharmacokinetics and toxicity, and finally their integration into multimodal imaging strategies. We also discuss challenges impeding the clinical translation of NIRF nanoprobes for molecular imaging of cancer. Whereas utilization of most NIRF nanoprobes remains at a proof-of-principle stage, optimizing the impact of nanomedicine in cancer patient diagnosis and management will probably be realized through persistent interdisciplinary amalgamation of diverse research fields.

    View details for DOI 10.1016/j.molmed.2010.08.006

    View details for Web of Science ID 000285727200004

    View details for PubMedID 20870460

  • PET Imaging of Tumor Neovascularization in a Transgenic Mouse Model with a Novel Cu-64-DOTA-Knottin Peptide CANCER RESEARCH Nielsen, C. H., Kimura, R. H., Withofs, N., Tran, P. T., Miao, Z., Cochran, J. R., Cheng, Z., Felsher, D., Kjaer, A., Willmann, J. K., Gambhir, S. S. 2010; 70 (22): 9022-9030

    Abstract

    Due to the high mortality of lung cancer, there is a critical need to develop diagnostic procedures enabling early detection of the disease while at a curable stage. Targeted molecular imaging builds on the positive attributes of positron emission tomography/computed tomography (PET/CT) to allow for a noninvasive detection and characterization of smaller lung nodules, thus increasing the chances of positive treatment outcome. In this study, we investigate the ability to characterize lung tumors that spontaneously arise in a transgenic mouse model. The tumors are first identified with small animal CT followed by characterization with the use of small animal PET with a novel 64Cu-1,4,7,10-tetra-azacylododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-knottin peptide that targets integrins upregulated during angiogenesis on the tumor associated neovasculature. The imaging results obtained with the knottin peptide are compared with standard 18F-fluorodeoxyglucose (FDG) PET small animal imaging. Lung nodules as small as 3 mm in diameter were successfully identified in the transgenic mice by small animal CT, and both 64Cu-DOTA-knottin 2.5F and FDG were able to differentiate lung nodules from the surrounding tissues. Uptake and retention of the 64Cu-DOTA-knottin 2.5F tracer in the lung tumors combined with a low background in the thorax resulted in a statistically higher tumor to background (normal lung) ratio compared with FDG (6.010.61 versus 4.360.68; P<0.05). Ex vivo biodistribution showed 64Cu-DOTA-knottin 2.5F to have a fast renal clearance combined with low nonspecific accumulation in the thorax. Collectively, these results show 64Cu-DOTA-knottin 2.5F to be a promising candidate for clinical translation for earlier detection and improved characterization of lung cancer.

    View details for DOI 10.1158/0008-5472.CAN-10-1338

    View details for Web of Science ID 000284213300008

    View details for PubMedID 21062977

  • Optical imaging of reporter gene expression using a positron-emission-tomography probe JOURNAL OF BIOMEDICAL OPTICS Liu, H., Ren, G., Liu, S., Zhang, X., Chen, L., Han, P., Cheng, Z. 2010; 15 (6)

    Abstract

    Reporter gene?reporter probe technology is one of the most important techniques in molecular imaging. Lately, many reporter gene?reporter probe systems have been coupled to different imaging modalities such as positron emission tomography (PET) and optical imaging (OI). It has been recently found that OI techniques could be used to monitor radioactive tracers in vitro and in living subjects. In this study, we further demonstrate that a reporter gene?nuclear reporter probe system [herpes simplex virus type-1 thymidine kinase (HSV1-tk) and 9-(4-(18)F-fluoro-3-[hydroxymethyl] butyl) guanine ([(18)F]FHBG)] could be successfully imaged by OI in vitro and in vivo. OI with radioactive reporter probes will facilitate and broaden the applications of reporter gene?reporter probe techniques in medical research.

    View details for DOI 10.1117/1.3514659

    View details for Web of Science ID 000287171100005

    View details for PubMedID 21198146

  • Dynamic Visualization of RGD-Quantum Dot Binding to Tumor Neovasculature and Extravasation in Multiple Living Mouse Models Using Intravital Microscopy SMALL Smith, B. R., Cheng, Z., De, A., Rosenberg, J., Gambhir, S. S. 2010; 6 (20): 2222-2229

    View details for DOI 10.1002/smll.201001022

    View details for Web of Science ID 000283890500003

    View details for PubMedID 20862677

  • Molecular Probes for Malignant Melanoma Imaging CURRENT PHARMACEUTICAL BIOTECHNOLOGY Ren, G., Pan, Y., Cheng, Z. 2010; 11 (6): 590-602

    Abstract

    Malignant melanoma represents a serious public health problem and is a deadly disease when it is diagnosed at late stage. Though (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) has been widely used clinically for melanoma imaging, other approaches to specifically identify, characterize, monitor and guide therapeutics for malignant melanoma are still needed. Consequently, many probes targeting general molecular events including metabolism, angiogenesis, hypoxia and apoptosis in melanoma have been successfully developed. Furthermore, probes targeting melanoma associated targets such as melanocortin receptor 1 (MC1R), melanin, etc. have undergone active investigation and have demonstrated high melanoma specificity. In this review, these molecular probes targeting diverse melanoma biomarkers have been summarized. Some of them may eventually contribute to the improvement of personalized management of malignant melanoma.

    View details for Web of Science ID 000281435100006

    View details for PubMedID 20497118

  • Near-Infrared Quantum Dots as Optical Probes for Tumor Imaging CURRENT TOPICS IN MEDICINAL CHEMISTRY Gao, J., Chen, X., Cheng, Z. 2010; 10 (12): 1147-1157

    Abstract

    Molecular imaging plays a key role in personalized medicine, which is the goal and future of patient management. Among the various molecular imaging modalities, optical imaging may be the fastest growing area for bioanalysis, and the major reason is the research on fluorescence semiconductor quantum dots (QDs) and dyes have evolved over the past two decades. The great efforts on the synthesis of QDs with fluorescence emission from UV to near-infrared (NIR) regions speed up the studies of QDs as optical probes for in vitro and in vivo molecular imaging. For in vivo applications, the fluorescent emission wavelength ideally should be in a region of the spectrum where blood and tissue absorb minimally and tissue penetration reach maximally, which is NIR region (typically 700-1000 nm). The goal of this review is to provide readers the basics of NIR-emitting QDs, the bioconjugate chemistry of QDs, and their applications for diagnostic tumor imaging. We will also discuss the benefits, challenges, limitations, perspective, and the future scope of NIR-emitting QDs for tumor imaging applications.

    View details for Web of Science ID 000279117800002

    View details for PubMedID 20388111

  • In vivo near-infrared fluorescence imaging of cancer with nanoparticle-based probes WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY He, X., Wang, K., Cheng, Z. 2010; 2 (4): 349-366

    Abstract

    The use of in vivo near-infrared fluorescence (NIRF) imaging techniques for sensitive cancer early detection is highly desirable, because biological tissues show very low absorption and autofluorescence in the NIR spectrum window. Cancer NIRF molecular imaging relies greatly on stable, highly specific and sensitive molecular probes. Nanoparticle-based NIRF probes have overcome some of the limitations of the conventional NIRF organic dyes, such as poor hydrophilicity and photostability, low quantum yield, insufficient stability in biological system, low detection sensitivity, etc. Therefore, a lot of efforts have been made to actively develop novel NIRF nanoparticles for in vivo cancer molecular imaging. The main focus of this article is to provide a brief overview of the synthesis, surface modification, and in vivo cancer imaging applications of nanoparticle-based NIRF probes, including dye-containing nanoparticles, NIRF quantum dots, and upconversion nanoparticles.

    View details for DOI 10.1002/wnan.85

    View details for Web of Science ID 000280014000003

    View details for PubMedID 20564463

  • Cu-64-Labeled Affibody Molecules for Imaging of HER2 Expressing Tumors MOLECULAR IMAGING AND BIOLOGY Cheng, Z., De Jesus, O. P., Kramer, D. J., De, A., Webster, J. M., Gheysens, O., Levi, J., Namavari, M., Wang, S., Park, J. M., Zhang, R., Liu, H., Lee, B., Syud, F. A., Gambhir, S. S. 2010; 12 (3): 316-324

    Abstract

    The development of molecular probes based on novel engineered protein constructs is under active investigation due to the great potential of this generalizable strategy for imaging a variety of tumor targets.In this report, human epidermal growth factor receptor type 2 (HER2)-binding Affibody molecules were radiolabeled with (64)Cu and their imaging ability was further evaluated in tumor mice models to understand the promise and limitations of such probes. The anti-HER2 Affibody molecules in monomeric (Z(HER2:477)) and dimeric [(Z(HER2:477))(2)] forms were site specifically modified with the maleimide-functionalized chelator, 1,4,7,10-tetraazacyclododecane-1,4,7-tris(acetic acid)-10-acetate mono (N-ethylmaleimide amide) (Mal-DOTA). The resulting DOTA-Affibody conjugates were radiolabeled with (64)Cu and evaluated in nude mice bearing subcutaneous SKOV3 tumors. Biodistribution experiments showed that tumor uptake values of (64)Cu-DOTA-Z(HER2:477) and (64)Cu-DOTA-(Z(HER2:477))(2) were 6.12 +/- 1.44% and 1.46 +/- 0.50% ID/g, respectively, in nude mice (n = 3 each) at 4 h postinjection. Moreover, (64)Cu-labeled monomer exhibited significantly higher tumor/blood ratio than that of radiolabeled dimeric counterpart at all time points examined in this study. MicroPET imaging of (64)Cu-DOTA-Z(HER2:477) in SKOV3 tumor mice clearly showed good and specific tumor localization. This study demonstrates that (64)Cu-labeled Z(HER2:477) is a promising targeted molecular probe for imaging HER2 receptor expression in living mice. Further work is needed to improve the excretion properties, hence dosimetry and imaging efficacy, of the radiometal-based probe.

    View details for DOI 10.1007/s11307-009-0256-6

    View details for Web of Science ID 000277375300010

    View details for PubMedID 19779897

  • Radiation-Luminescence-Excited Quantum Dots for in vivo Multiplexed Optical Imaging SMALL Liu, H., Zhang, X., Xing, B., Han, P., Gambhir, S. S., Cheng, Z. 2010; 6 (10): 1087-1091

    View details for DOI 10.1002/smll.200902408

    View details for Web of Science ID 000278629300004

    View details for PubMedID 20473988

  • Cy5.5-labeled Affibody molecule for near-infrared fluorescent optical imaging of epidermal growth factor receptor positive tumors JOURNAL OF BIOMEDICAL OPTICS Miao, Z., Ren, G., Liu, H., Jiang, L., Cheng, Z. 2010; 15 (3)

    Abstract

    Affibody protein is an engineered protein scaffold with a three-helical bundle structure. Affibody molecules of small size (7 kD) have great potential for targeting overexpressed cancer biomarkers in vivo. To develop an Affibody-based molecular probe for in vivo optical imaging of epidermal growth factor receptor (EGFR) positive tumors, an anti-EGFR Affibody molecule, Ac-Cys-Z(EGFR:1907) (7 kD), is site-specifically conjugated with a near-IR fluorescence dye, Cy5.5-mono-maleimide. Using fluorescent microscopy, the binding specificity of the probe Cy5.5-Z(EGFR:1907) is checked by a high-EGFR-expressing A431 cell and low-EGFR-expressing MCF7 cells. The binding affinity of Cy5.5-Z(EGFR:1907) (K(D)) to EGFR is 43.6+/-8.4 nM, as determined by flow cytometry. For an in vivo imaging study, the probe shows fast tumor targeting and good tumor contrast as early as 0.5 h postinjection (p.i.) for A431 tumors, while MCF7 tumors are barely visible. An ex vivo imaging study also demonstrates that Cy5.5-Z(EGFR:1907) has high tumor, liver, and kidney uptakes at 24 h p.i.. In conclusion, Cy5.5-Z(EGFR:1907) shows good affinity and high specificity to the EGFR. There is rapid achievement of good tumor-to-normal-tissue contrasts of Cy5.5-Z(EGFR:1907), thus demonstrating its potential for EGFR-targeted molecular imaging of cancers.

    View details for DOI 10.1117/1.3432738

    View details for Web of Science ID 000280642900022

    View details for PubMedID 20615009

  • Small-Animal PET Imaging of Human Epidermal Growth Factor Receptor Positive Tumor with a Cu-64 Labeled Affibody Protein BIOCONJUGATE CHEMISTRY Miao, Z., Ren, G., Liu, H., Jiang, L., Cheng, Z. 2010; 21 (5): 947-954

    Abstract

    Epidermal growth factor receptor (EGFR) has become an attractive target for cancer molecular imaging and therapy. Affibody proteins against EGFR have been reported, and thus, we were interested in evaluating their potential for positron emission tomography (PET) imaging of EGFR positive cancer. An Affibody analogue (Ac-Cys-Z(EGFR:1907)) binding to EGFR was made through conventional solid phase peptide synthesis. The purified protein was site-specifically coupled with the 1,4,7,10-tetraazacyclododecane-1,4,7-tris-aceticacid-10-maleimidethylacetamide (maleimido-mono-amide-DOTA) to produce the bioconjugate, DOTA-Z(EGFR:1907). (64)Cu labeled probe (64)Cu-DOTA-Z(EGFR:1907) displayed a moderate specific activity (5-8 MBq/nmol, 22-35 microCi/microg). Cell uptake assays by pre-incubating without or with 300 times excess unlabeled Ac-Cys-Z(EGFR:1907) showed high EGFR-specific uptake (20% applied activity at 0.5 h) in A431 epidermoid carcinoma cancer cells. The affinity (K(D)) of (64)Cu-DOTA-Z(EGFR:1907) as tested by cell saturation analysis was 20 nM. The serum stability test showed excellent stability of the probe with >95% intact after 4 h of incubation in mouse serum. In vivo small-animal PET imaging showed fast tumor targeting, high tumor accumulation (approximately 10% ID/g at 1 h p.i.), and good tumor-to-normal tissue contrast of (64)Cu-DOTA-Z(EGFR:1907) spiked with a wide dose range of Ac-Cys-Z(EGFR:1907). Bio-distribution studies further demonstrated that the probe had high tumor, blood, liver, and kidney uptakes, while blood radioactivity concentration dropped dramatically at increased spiking doses. Co-injection of the probe with 500 microg of Ac-Cys-Z(EGFR:1907) for blocking significantly reduced the tumor uptake. Thus, (64)Cu-DOTA-Z(EGFR:1907) showed potential as a high tumor contrast EGFR PET imaging reagent. The probe spiked with 50 microg of Ac-Cys-Z(EGFR:1907) improved tumor imaging contrast which may have important clinical applications.

    View details for DOI 10.1021/bc900515p

    View details for Web of Science ID 000277683300020

    View details for PubMedID 20402512

  • In Vivo Tumor-Targeted Fluorescence Imaging Using Near-Infrared Non-Cadmium Quantum Dots BIOCONJUGATE CHEMISTRY Gao, J., Chen, K., Xie, R., Xie, J., Yan, Y., Cheng, Z., Peng, X., Chen, X. 2010; 21 (4): 604-609

    Abstract

    This article reported the high tumor targeting efficacy of RGD peptide labeled near-infrared (NIR) non-cadmium quantum dots (QDs). After using poly(ethylene glycol) to encapsulate InAs/InP/ZnSe QDs (emission maximum at about 800 nm), QD800-PEG dispersed well in PBS buffer with the hydrodynamic diameter (HD) of 15.9 nm and the circulation half-life of approximately 29 min. After coupling QD800-PEG with arginine-glycine-aspartic acid (RGD) or arginine-alanine-aspartic acid (RAD) peptides, we used nude mice bearing subcutaneous U87MG tumor as models to test tumor-targeted fluorescence imaging. The results indicated that the tumor uptake of QD800-RGD is much higher than those of QD800-PEG and QD800-RAD. The semiquantitative analysis of the region of interest (ROI) showed a high tumor uptake of 10.7 +/- 1.5%ID/g in mice injected with QD800-RGD, while the tumor uptakes of QD800-PEG and QD800-RAD were 2.9 +/- 0.3%ID/g and 4.0 +/- 0.5%ID/g, respectively, indicating the specific tumor targeting of QD800-RGD. The high reproducibility of bioconjunction between QDs and the RGD peptide and the feasibility of QD-RGD bioconjugates as tumor-targeted fluorescence probes warrant the successful application of QDs for in vivo molecular imaging.

    View details for DOI 10.1021/bc900323v

    View details for Web of Science ID 000276817800006

    View details for PubMedID 20369817

  • Molecular Optical Imaging with Radioactive Probes PLOS ONE Liu, H., Ren, G., Miao, Z., Zhang, X., Tang, X., Han, P., Gambhir, S. S., Cheng, Z. 2010; 5 (3)

    Abstract

    Optical imaging (OI) techniques such as bioluminescence and fluorescence imaging have been widely used to track diseases in a non-invasive manner within living subjects. These techniques generally require bioluminescent and fluorescent probes. Here we demonstrate the feasibility of using radioactive probes for in vivo molecular OI.By taking the advantages of low energy window of light (1.2-3.1 eV, 400-1000 nm) resulting from radiation, radionuclides that emit charged particles such as beta(+) and beta(-) can be successfully imaged with an OI instrument. In vivo optical images can be obtained for several radioactive probes including 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG), Na(18)F, Na(131)I, (90)YCl(3) and a (90)Y labeled peptide that specifically target tumors.These studies demonstrate generalizability of radioactive OI technique. It provides a new molecular imaging strategy and will likely have significant impact on both small animal and clinical imaging.

    View details for DOI 10.1371/journal.pone.0009470

    View details for Web of Science ID 000274997100016

    View details for PubMedID 20208993

  • Evaluation of a Cu-64-Labeled Cystine-Knot Peptide Based on Agouti-Related Protein for PET of Tumors Expressing alpha(v)beta(3) Integrin JOURNAL OF NUCLEAR MEDICINE Jiang, L., Kimura, R. H., Miao, Z., Silverman, A. P., Ren, G., Liu, H., Li, P., Gambhir, S. S., Cochran, J. R., Cheng, Z. 2010; 51 (2): 251-258

    Abstract

    Recently, a truncated form of the agouti-related protein (AgRP), a 4-kDa cystine-knot peptide of human origin, was used as a scaffold to engineer mutants that bound to alpha(v)beta(3) integrin with high affinity and specificity. In this study, we evaluated the potential of engineered integrin-binding AgRP peptides for use as cancer imaging agents in living subjects.Engineered AgRP peptides were prepared by solid-phase peptide synthesis and were folded in vitro and purified by reversed-phase high-performance liquid chromatography. Competition assays were used to measure the relative binding affinities of engineered AgRP peptides for integrin receptors expressed on the surface of U87MG glioblastoma cells. The highest-affinity mutant, AgRP clone 7C, was site-specifically conjugated with 1,4,7,10-tetra-azacyclododecane-N,N',N''N'''-tetraacetic acid (DOTA). The resulting bioconjugate, DOTA-AgRP-7C, was radiolabeled with (64)Cu for biodistribution analysis and small-animal PET studies in mice bearing U87MG tumor xenografts. In addition to serum stability, the in vivo metabolic stability of (64)Cu-DOTA-AgRP-7C was assessed after injection and probe recovery from mouse kidney, liver, tumor, and urine.AgRP-7C and DOTA-AgRP-7C bound with high affinity to integrin receptors expressed on U87MG cells (half maximal inhibitory concentration values, 20 +/- 4 and 14 +/- 2 nM, respectively). DOTA-AgRP-7C was labeled with (64)Cu with high radiochemical purity (>99%). In biodistribution and small-animal PET studies, (64)Cu-DOTA-AgRP-7C displayed rapid blood clearance, good tumor uptake and retention (2.70 +/- 0.93 percentage injected dose per gram [%ID/g] and 2.37 +/- 1.04 %ID/g at 2 and 24 h, respectively), and high tumor-to-background tissue ratios. The integrin-binding specificity of (64)Cu-DOTA-AgRP-7C was confirmed in vitro and in vivo by showing that a large molar excess of the unlabeled peptidomimetic c(RGDyK) could block probe binding and tumor uptake. Serum stability and in vivo metabolite assays demonstrated that engineered AgRP peptides are sufficiently stable for in vivo molecular imaging applications.A radiolabeled version of the engineered AgRP peptide 7C showed promise as a PET agent for tumors that express the alpha(v)beta(3) integrin. Collectively, these results validate AgRP-based cystine-knot peptides for use in vivo as molecular imaging agents and provide support for the general use of AgRP as a scaffold to develop targeting peptides, and hence diagnostics, against other tumor receptors.

    View details for DOI 10.2967/jnumed.109.069831

    View details for Web of Science ID 000274152800028

    View details for PubMedID 20124048

  • Ultrasmall Near-Infrared Non-cadmium Quantum Dots for in vivo Tumor Imaging SMALL Gao, J., Chen, K., Xie, R., Xie, J., Lee, S., Cheng, Z., Peng, X., Chen, X. 2010; 6 (2): 256-261

    Abstract

    The high tumor uptake of ultrasmall near-infrared quantum dots (QDs) attributed to the enhanced permeability and retention effect is reported. InAs/InP/ZnSe QDs coated by mercaptopropionic acid (MPA) exhibit an emission wavelength of about 800 nm (QD800-MPA) with very small hydrodynamic diameter (<10 nm). Using 22B and LS174T tumor xenograft models, in vivo and ex vivo imaging studies show that QD800-MPA is highly accumulated in the tumor area, which is very promising for tumor detection in living mice. The ex vivo elemental analysis (Indium) using inductively coupled plasma (ICP) spectrometry confirm the tumor uptake of QDs. The ICP data are consistent with the in vivo and ex vivo fluorescence imaging. Human serum albumin (HSA)-coated QD800-MPA nanoparticles (QD800-MPA-HSA) show reduced localization in mononuclear phagocytic system-related organs over QD800-MPA plausibly due to the low uptake of QD800-MPA-HSA in macrophage cells. QD800-MPA-HSA may have great potential for in vivo fluorescence imaging.

    View details for DOI 10.1002/smll.200901672

    View details for Web of Science ID 000274363800018

    View details for PubMedID 19911392

  • HSA coated MnO nanoparticles with prominent MRI contrast for tumor imaging CHEMICAL COMMUNICATIONS Huang, J., Xie, J., Chen, K., Bu, L., Lee, S., Cheng, Z., Li, X., Chen, X. 2010; 46 (36): 6684-6686

    Abstract

    We report in this Communication a facile, two-step surface modification strategy to achieve manganese oxide nanoparticles with prominent MRI T1 contrast. In a U87MG glioblastoma xenograft model, we confirmed that the particles can accumulate efficiently in tumor area to induce effective T1 signal alteration.

    View details for DOI 10.1039/c0cc01041c

    View details for Web of Science ID 000281604500010

    View details for PubMedID 20730157

  • Synthesis of porous and nonporous ZnO nanobelt, multipod, and hierarchical nanostructure from Zn-HDS J Solid State Chem Jang ES, W. K. 2010; 183 (8): Available online 2 J
  • A Dual-Labeled Knottin Peptide for PET and Near-Infrared Fluorescence Imaging of Integrin Expression in Living Subjects. Bioconjugate chemistry Kimura, R. H., Miao, Z., Cheng, Z., Gambhir, S. S., Cochran, J. R. 2010

    Abstract

    Previously, we used directed evolution to engineer mutants of the Ecballium elaterium trypsin inhibitor (EETI-II) knottin that bind to alpha(v)beta(3) and alpha(v)beta(5) integrin receptors with low nanomolar affinity, and showed that Cy5.5- or (64)Cu-DOTA-labeled knottin peptides could be used to image integrin expression in mouse tumor models using near-infrared fluorescence (NIRF) imaging or positron emission tomography (PET). Here, we report the development of a dual-labeled knottin peptide conjugated to both NIRF and PET imaging agents for multimodality imaging in living subjects. We created an orthogonally protected peptide-based linker for stoichiometric coupling of (64)Cu-DOTA and Cy5.5 onto the knottin N-terminus and confirmed that conjugation did not affect binding to alpha(v)beta(3) and alpha(v)beta(5) integrins. NIRF and PET imaging studies in tumor xenograft models showed that Cy5.5 conjugation significantly increased kidney uptake and retention compared to the knottin peptide labeled with (64)Cu-DOTA alone. In the tumor, the dual-labeled (64)Cu-DOTA/Cy5.5 knottin peptide showed decreased wash-out leading to significantly better retention (p < 0.05) compared to the (64)Cu-DOTA-labeled knottin peptide. Tumor uptake was significantly reduced (p < 0.05) when the dual-labeled knottin peptide was coinjected with an excess of unlabeled competitor and when tested in a tumor model with lower levels of integrin expression. Finally, plots of tumor-to-background tissue ratios for Cy5.5 versus (64)Cu uptake were well-correlated over several time points post injection, demonstrating pharmacokinetic cross validation of imaging labels. This dual-modality NIRF/PET imaging agent is promising for further development in clinical applications where high sensitivity and high resolution are desired, such as detection of tumors located deep within the body and image-guided surgical resection.

    View details for PubMedID 20131753

  • An Engineered Knottin Peptide Labeled with F-18 for PET Imaging of Integrin Expression BIOCONJUGATE CHEMISTRY Miao, Z., Ren, G., Liu, H., Kimura, R. H., Jiang, L., Cochran, J. R., Gambhir, S. S., Cheng, Z. 2009; 20 (12): 2342-2347

    Abstract

    Knottins are small constrained polypeptides that share a common disulfide-bonded framework and a triple-stranded beta-sheet fold. Previously, directed evolution of the Ecballium elaterium trypsin inhibitor (EETI-II) knottin led to the identification of a mutant that bound to tumor-specific alpha(v)beta(3) and alpha(v)beta(5) integrin receptors with low nanomolar affinity. The objective of this study was to prepare and evaluate a radiofluorinated version of this knottin (termed 2.5D) for microPET imaging of integrin positive tumors in living subjects. Knottin peptide 2.5D was prepared by solid-phase synthesis and folded in vitro, and its free N-terminal amine was reacted with N-succinimidyl-4-18/19F-fluorobenzoate (18/19F-SFB) to produce the fluorinated peptide 18/19F-FB-2.5D. The binding affinities of unlabeled knottin peptide 2.5D and 19F-FB-2.5D to U87MG glioblastoma cells were measured by competition binding assay using 125I-labeled echistatin. It was found that unlabeled 2.5D and 19F-FB-2.5D competed with 125I-echistatin for binding to cell surface integrins with IC(50) values of 20.3 +/- 7.3 and 13.2 +/- 5.4 nM, respectively. Radiosynthesis of 18F-FB-2.5D resulted in a product with high specific activity (ca. 100 GBq/micromol). Next, biodistribution and positron emission tomography (PET) imaging studies were performed to evaluate the in vivo behavior of 18F-FB-2.5D. Approximately 3.7 MBq 18F-FB-2.5D was injected into U87MG tumor-bearing mice via the tail vein. Biodistribution studies demonstrated that 18F-FB-2.5D had moderate tumor uptake at 0.5 h post injection, and coinjection of a large excess of the unlabeled peptidomimetic c(RGDyK) as a blocking agent significantly reduced tumor uptake (1.90 +/- 1.15 vs 0.57 +/- 0.14%ID/g, 70% inhibition, P < 0.05). In vivo microPET imaging showed that 18F-FB-2.5D rapidly accumulated in the tumor and quickly cleared from the blood through the kidneys, allowing excellent tumor-to-normal tissue contrast to be obtained. Collectively, 18F-FB-2.5D allows integrin-specific PET imaging of U87MG tumors with good contrast and further demonstrates that knottins are excellent peptide scaffolds for development of PET probes with potential for clinical translation.

    View details for DOI 10.1021/bc900361g

    View details for Web of Science ID 000272690100018

    View details for PubMedID 19908826

  • PET of Malignant Melanoma Using F-18-Labeled Metallopeptides JOURNAL OF NUCLEAR MEDICINE Ren, G., Liu, Z., Miao, Z., Liu, H., Subbarayan, M., Chin, F. T., Zhang, L., Gambhir, S. S., Cheng, Z. 2009; 50 (11): 1865-1872

    Abstract

    Melanocortin type 1 receptor (MC1R), also known as alpha-melanocyte-stimulating hormone (alpha-MSH) receptor, is an attractive molecular target for melanoma imaging and therapy. An (18)F-labeled linear alpha-MSH peptide ((18)F-FB-Ac-Nle-Asp-His-d-Phe-Arg-Trp-Gly-Lys-NH(2) [NAPamide]) shows promising melanoma imaging properties but with only moderate tumor uptake and retention. A transition metal rhenium-cyclized alpha-MSH peptide, ReO[Cys(3,4,10),d-Phe(7),Arg(11)]alpha-MSH(3-13) (ReCCMSH(Arg(11))), has shown high in vitro binding affinity to MC1R and excellent in vivo melanoma-targeting profiles when labeled with radiometals. Therefore, we hypothesized that ReCCMSH(Arg(11)) could be a good platform for the further development of an (18)F-labeled probe for PET of MC1R-positive malignant melanoma.In this study, the metallopeptide Ac-d-Lys-ReCCMSH(Arg(11)) was synthesized using conventional solid-phase peptide synthesis chemistry and a rhenium cyclization reaction. The resulting peptides were then labeled with N-succinimidyl-4-(18)F-fluorobenzoate ((18)F-SFB). The (18)F-labeled metallopeptides were further tested for their in vitro receptor binding affinities, in vivo biodistribution, and PET imaging properties.Both isomers of Ac-d-Lys-ReCCMSH(Arg(11)), named as RMSH-1 and RMSH-2, were purified and identified by high-performance liquid chromatography. The binding affinities of RMSH-1 and RMSH-2 and their respective (19)F-SFB-conjugated peptides ((19)F-FB-RMSH-1 and (19)F-FB-RMSH-2) were all determined to be within nanomolar range. Both (18)F-labeled metallopeptides showed good tumor uptake in the B16F10 murine model, with high MC1R expression, but much lower uptake in the A375M human melanoma xenografted in mice, indicating low MC1R expression. (18)F-FB-RMSH-1, when compared with (18)F-FB-RMSH-2, displayed more favorable in vivo performance in terms of slightly higher tumor uptakes and much lower accumulations in the kidney and liver at 2 h after injection. Small-animal PET of (18)F-FB-RMSH-1 and -2 in mice bearing B16F10 tumors at 1 and 2 h showed good tumor imaging quality. As expected, much lower tumor uptakes and poorer tumor-to-normal organ contrasts were observed for the A375M model than for the B16F10 model. (18)F-FB-RMSH-1 and -2 showed higher tumor uptake and better tumor retention than did (18)F-FB-NAPamide.Specific in vivo targeting of (18)F-FB-RMSH-1 to malignant melanoma was successfully achieved in preclinical models with high MC1R expression. Thus, the radiofluorinated metallopeptide (18)F-FB-RMSH-1 is a promising molecular probe for PET of MC1R-positive tumors.

    View details for DOI 10.2967/jnumed.109.062877

    View details for Web of Science ID 000272554100021

    View details for PubMedID 19837749

  • Melanin-Targeted Preclinical PET Imaging of Melanoma Metastasis JOURNAL OF NUCLEAR MEDICINE Ren, G., Miao, Z., Liu, H., Jiang, L., Limpa-Amara, N., Mahmood, A., Gambhir, S. S., Cheng, Z. 2009; 50 (10): 1692-1699

    Abstract

    Dialkylamino-alkyl-benzamides possess an affinity for melanin, suggesting that labeling of such benzamides with (18)F could potentially produce melanin-targeted PET probes able to identify melanotic melanoma metastases in vivo with high sensitivity and specificity.In this study, N-[2-(diethylamino)ethyl]-4-(18)F-fluorobenzamide ((18)F-FBZA) was synthesized via a 1-step conjugation reaction. The sigma-receptor binding affinity of (19)F-FBZA was determined along with the in vitro cellular uptake of radiofluorinated (18)F-FBZA in B16F10 cells. In vivo distribution and small-animal PET studies were conducted on mice bearing B16F10 melanoma, A375M amelanotic melanoma, and U87MG tumors, and comparative studies were performed with (18)F-FDG PET in the melanoma models.In vitro, uptake of (18)F-FBZA was significantly higher in B16F10 cells treated with l-tyrosine (P < 0.001). In vivo, (18)F-FBZA displayed significant tumor uptake; at 2 h, 5.94 +/- 1.83 percentage injected dose (%ID) per gram was observed in B16F10 tumors and only 0.75 +/- 0.09 %ID/g and 0.56 +/- 0.13 %ID/g was observed in amelanotic A375M and U87MG tumors, respectively. Lung uptake was significantly higher in murine lungs bearing melanotic B16F10 pulmonary metastases than in normal murine lungs (P < 0.01). Small-animal PET clearly identified melanotic lesions in both primary and pulmonary metastasis B16F10 tumor models. Coregistered micro-CT with small-animal PET along with biopsies further confirmed the presence of tumor lesions in the mouse lungs.(18)F-FBZA specifically targets primary and metastatic melanotic melanoma lesions with high tumor uptake and may have translational potential.

    View details for DOI 10.2967/jnumed.109.066175

    View details for Web of Science ID 000272553600023

    View details for PubMedID 19759116

  • A 2-Helix Small Protein Labeled with Ga-68 for PET Imaging of HER2 Expression JOURNAL OF NUCLEAR MEDICINE Ren, G., Zhang, R., Liu, Z., Webster, J. M., Miao, Z., Gambhir, S. S., Syud, F. A., Cheng, Z. 2009; 50 (9): 1492-1499

    Abstract

    Affibody molecules are a class of scaffold proteins being developed into a generalizable approach to targeting tumors. Many 3-helix-based Affibody proteins have shown excellent in vivo properties for tumor imaging and therapy. By truncating one alpha-helix that is not responsible for receptor recognition in the Affibody and maturating the protein affinity through synthetic strategies, we have successfully identified in our previous research several small 2-helix proteins with excellent binding affinities to human epidermal growth factor receptor type 2 (HER2). With preferential properties such as faster blood clearance and tumor accumulation, lower immunogenic potential, and facile and economically viable synthetic schemes, we hypothesized that these 2-helix protein binders could become excellent molecular imaging probes for monitoring HER2 expression and modulation.In this study, a 2-helix small protein, MUT-DS, was chemically modified with a metal chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). DOTA-MUT-DS was then site-specifically radiolabeled with an important PET radionuclide, (68)Ga. The resulting radiolabeled anti-HER2 2-helix molecule was further evaluated as a potential molecular probe for small-animal PET HER2 imaging in a SKOV3 tumor mouse model.The 2-helix DOTA-MUT-DS showed high HER2-binding affinity (dissociation constant, 4.76 nM). The radiolabeled probe displayed high stability in mouse serum and specificity toward HER2 in cell cultures. Biodistribution and small-animal PET studies further showed that (68)Ga-DOTA-MUT-DS had rapid and high SKOV3 tumor accumulation and quick clearance from normal organs. The specificity of (68)Ga-DOTA-MUT-DS for SKOV3 tumors was confirmed by monitoring modulation of HER2 protein on treatment of tumor mice with heat shock protein 90 inhibitor 17-N,N-dimethyl ethylene diamine-geldanamycin in vivo.This proof-of-concept research clearly demonstrated that synthetic 2-helix (68)Ga-DOTA-MUT-DS is a promising PET probe for imaging HER2 expression in vivo. The Affibody-derived small 2-helix protein scaffold has great potential for developing targeting agents for a variety of tumor-associated biomarkers.

    View details for DOI 10.2967/jnumed.109.064287

    View details for Web of Science ID 000272548900023

    View details for PubMedID 19690041

  • Visualizing Implanted Tumors in Mice with Magnetic Resonance Imaging Using Magnetotactic Bacteria CLINICAL CANCER RESEARCH Benoit, M. R., Mayer, D., Barak, Y., Chen, I. Y., Hu, W., Cheng, Z., Wang, S. X., Spielman, D. M., Gambhir, S. S., Matin, A. 2009; 15 (16): 5170-5177

    Abstract

    To determine if magnetotactic bacteria can target tumors in mice and provide positive contrast for visualization using magnetic resonance imaging.The ability of the magnetotactic bacterium, Magnetospirillum magneticum AMB-1 (referred to from here as AMB-1), to confer positive magnetic resonance imaging contrast was determined in vitro and in vivo. For the latter studies, AMB-1 were injected either i.t. or i.v. Bacterial growth conditions were manipulated to produce small (approximately 25-nm diameter) magnetite particles, which were observed using transmission electron microscopy. Tumor targeting was confirmed using 64Cu-labeled bacteria and positron emission tomography and by determination of viable cell counts recovered from different organs and the tumor.We show that AMB-1 bacteria with small magnetite particles generate T1-weighted positive contrast, enhancing in vivo visualization by magnetic resonance imaging. Following i.v. injection of 64Cu-labeled AMB-1, positron emission tomography imaging revealed increasing colonization of tumors and decreasing infection of organs after 4 hours. Viable cell counts showed that, by day 6, the bacteria had colonized tumors but were cleared completely from other organs. Magnetic resonance imaging showed a 1.22-fold (P = 0.003) increased positive contrast in tumors on day 2 and a 1.39-fold increase (P = 0.0007) on day 6.Magnetotactic bacteria can produce positive magnetic resonance imaging contrast and colonize mouse tumor xenografts, providing a potential tool for improved magnetic resonance imaging visualization in preclinical and translational studies to track cancer.

    View details for DOI 10.1158/1078-0432.CCR-08-3206

    View details for Web of Science ID 000269024900019

    View details for PubMedID 19671860

  • Engineered Knottin Peptides: A New Class of Agents for Imaging Integrin Expression in Living Subjects CANCER RESEARCH Kimura, R. H., Cheng, Z., Gambhir, S. S., Cochran, J. R. 2009; 69 (6): 2435-2442

    Abstract

    There is a critical need for molecular imaging agents to detect cell surface integrin receptors that are present in human cancers. Previously, we used directed evolution to engineer knottin peptides that bind with high affinity ( approximately 10 to 30 nmol/L) to integrin receptors that are overexpressed on the surface of tumor cells and the tumor neovasculature. To evaluate these peptides as molecular imaging agents, we site-specifically conjugated Cy5.5 or (64)Cu-1,4,7,10-tetra-azacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) to their N termini, and used optical and positron emission tomography (PET) imaging to measure their uptake and biodistribution in U87MG glioblastoma murine xenograft models. NIR fluorescence and microPET imaging both showed that integrin binding affinity plays a strong role in the tumor uptake of knottin peptides. Tumor uptake at 1 hour postinjection for two high-affinity (IC(50), approximately 20 nmol/L) (64)Cu-DOTA-conjugated knottin peptides was 4.47% +/- 1.21% and 4.56% +/- 0.64% injected dose/gram (%ID/g), compared with a low-affinity knottin peptide (IC(50), approximately 0.4 mumol/L; 1.48 +/- 0.53%ID/g) and c(RGDyK) (IC(50), approximately 1 mumol/L; 2.32 +/- 0.55%ID/g), a low-affinity cyclic pentapeptide under clinical development. Furthermore, (64)Cu-DOTA-conjugated knottin peptides generated lower levels of nonspecific liver uptake ( approximately 2%ID/g) compared with c(RGDyK) ( approximately 4%ID/g) 1 hour postinjection. MicroPET imaging results were confirmed by in vivo biodistribution studies. (64)Cu-DOTA-conjugated knottin peptides were stable in mouse serum, and in vivo metabolite analysis showed minimal degradation in the blood or tumor upon injection. Thus, engineered integrin-binding knottin peptides show great potential as clinical diagnostics for a variety of cancers.

    View details for DOI 10.1158/0008-5472.CAN-08-2495

    View details for Web of Science ID 000264541300037

    View details for PubMedID 19276378

  • A Novel Method for Direct Site-Specific Radiolabeling of Peptides Using [F-18]FDG BIOCONJUGATE CHEMISTRY Namavari, M., Cheng, Z., Zhang, R., De, A., Levi, J., Hoerner, J. K., Yaghoubi, S. S., Syud, F. A., Gambhir, S. S. 2009; 20 (3): 432-436

    Abstract

    We have used the well-accepted and easily available 2-[(18)F]fluoro-2-deoxyglucose ([(18)F]FDG) positron emission tomography (PET) tracer as a prosthetic group for synthesis of (18)F-labeled peptides. We herein report the synthesis of [(18)F]FDG-RGD ((18)F labeled linear RGD) and [(18)F]FDG-cyclo(RGD(D)YK) ((18)F labeled cyclic RGD) as examples of the use of [(18)F]FDG. We have successfully prepared [(18)F]FDG-RGD and [(18)F]FDG-cyclo(RGD(D)YK) in 27.5% and 41% radiochemical yields (decay corrected) respectively. The receptor binding affinity study of FDG-cyclo(RGD(D)YK) for integrin alpha(v)beta(3), using alpha(v)beta(3) positive U87MG cells confirmed a competitive displacement with (125)I-echistatin as a radioligand. The IC(50) value for FDG-cyclo(RGD(D)YK) was determined to be 0.67 +/- 0.19 muM. High-contrast small animal PET images with relatively moderate tumor uptake were observed for [(18)F]FDG-RGD and [(18)F]FDG-cyclo(RGD(D)YK) as PET probes in xenograft models expressing alpha(v)beta(3) integrin. In conclusion, we have successfully used [(18)F]FDG as a prosthetic group to prepare (18)F]FDG-RGD and [(18)F]FDG-cyclic[RGD(D)YK] based on a simple one-step radiosynthesis. The one-step radiosynthesis methodology consists of chemoselective oxime formation between an aminooxy-functionalized peptide and [(18)F]FDG. The results have implications for radiolabeling of other macromolecules and would lead to a very simple strategy for routine preclinical and clinical use.

    View details for DOI 10.1021/bc800422b

    View details for Web of Science ID 000264389800005

    View details for PubMedID 19226160

  • Engineered two-helix small proteins for molecular recognition. ChemBioChem Webster JM, Zhang R, Gambhir SS, Cheng Z*, Syud FA*. 2009; 10: 1293-6
  • Photoactivatable caged bioluminescent probes for luciferase activity measurement. Chem Commun Shao Q, Jiang T, Ren G, Cheng Z*, Xing B*. 2009; 15: 4028-30
  • Photoacoustic Molecular Imaging using Single Walled Carbon Nanotubes in Living Mice PHOTONS PLUS ULTRASOUND: IMAGING AND SENSING 2009 de la Zerda, A., Zavaleta, C., Keren, S., Vaithilingam, S., Bodapati, S., Teed, R., Liu, Z., Levi, J., Smith, B. R., Ma, T., Oralkan, O., Cheng, Z., Chen, X., Dai, H., Khuri-Yakub, B. T., Gambhir, S. S. 2009; 7177

    View details for DOI 10.1117/12.806497

    View details for Web of Science ID 000285714100066

  • Near-infrared fluorescent deoxyglucose analog for optical imaging of experimental arthritis. J Innov Opt Health Sci. Liu X, Xiong Z, Lee S, Levi J, Yaghoubi S, Biswal S, Gambhir SS, Cheng Z. 2009; 2: 179-187
  • Particle Size, Surface Coating, and PEGylation Influence the Biodistribution of Quantum Dots in Living Mice SMALL Schipper, M. L., Iyer, G., Koh, A. L., Cheng, Z., Ebenstein, Y., Aharoni, A., Keren, S., Bentolila, L. A., Li, J., Rao, J., Chen, X., Banin, U., Wu, A. M., Sinclair, R., Weiss, S., Gambhir, S. S. 2009; 5 (1): 126-134

    Abstract

    This study evaluates the influence of particle size, PEGylation, and surface coating on the quantitative biodistribution of near-infrared-emitting quantum dots (QDs) in mice. Polymer- or peptide-coated 64Cu-labeled QDs 2 or 12 nm in diameter, with or without polyethylene glycol (PEG) of molecular weight 2000, are studied by serial micropositron emission tomography imaging and region-of-interest analysis, as well as transmission electron microscopy and inductively coupled plasma mass spectrometry. PEGylation and peptide coating slow QD uptake into the organs of the reticuloendothelial system (RES), liver and spleen, by a factor of 6-9 and 2-3, respectively. Small particles are in part renally excreted. Peptide-coated particles are cleared from liver faster than physical decay alone would suggest. Renal excretion of small QDs and slowing of RES clearance by PEGylation or peptide surface coating are encouraging steps toward the use of modified QDs for imaging living subjects.

    View details for DOI 10.1002/smll.200800003

    View details for Web of Science ID 000262895300019

    View details for PubMedID 19051182

  • 123I labeled metaiodobenzylguanidine for diagnosis of neuroendocrine tumors Reports in Medical Imaging Jiang L, S. L. 2009; 2: 79-89
  • Targeted microbubbles for imaging tumor angiogenesis: Assessment of whole-body biodistribution with dynamic micro-PET in mice RADIOLOGY Willmann, J. K., Cheng, Z., Davis, C., Lutz, A. M., Schipper, M. L., Nielsen, C. H., Gambhir, S. S. 2008; 249 (1): 212-219

    Abstract

    To evaluate in vivo whole-body biodistribution of microbubbles (MBs) targeted to tumor angiogenesis-related vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) by using dynamic micro-positron emission tomography (PET) in living mice.Animal protocols were approved by the Institutional Administrative Panel on Laboratory Animal Care. Lipid-shell perfluorocarbon-filled MBs, targeted to VEGFR2 via anti-VEGFR2 antibodies, were radiolabeled by conjugating the radiofluorination agent N-succinimidyl-4-[(18)F]fluorobenzoate (SFB) to the anti-VEGFR2 antibodies. These MBs were then injected intravenously into nude mice (n = 4) bearing angiosarcomas, and the whole-body biodistribution of these probes was assessed for 60 minutes by using dynamic micro-PET. Results were compared with ex vivo gamma counting (n = 6) and immunofluorescence staining (n = 6). Control studies in angiosarcoma-bearing mice were performed with injection of the radiolabeled antibodies alone (n = 3) or free SFB (n = 3). A mixed-effects regression of MB accumulation on fixed effects of time and tissue type (tumor or muscle) and random effect of animal was performed.VEGFR2-targeted MBs rapidly cleared from the blood circulation (50% blood clearance after approximately 3.5 minutes) and accumulated in the liver (mean, 33.4% injected dose [ID]/g +/- 13.7 [standard deviation] at 60 minutes) and spleen (mean, 9.3% ID/g +/- 6.5 at 60 minutes) on the basis of micro-PET imaging. These findings were confirmed with ex vivo gamma counting. Uptake of targeted MBs was significantly higher (P < .0001) in tumor than in adjacent skeletal muscle tissue. Immunofluorescence staining demonstrated accumulation of the targeted MBs within hepatic Kupffer cells and splenic macrophages. Biodistribution of the radiolabeled antibodies and free SFB differed from the distribution of the targeted MBs.Dynamic micro-PET allows assessment of in vivo biodistribution of VEGFR2-targeted MBs.

    View details for DOI 10.1148/radiol.2491072050

    View details for Web of Science ID 000259505200025

    View details for PubMedID 18695212

  • Noninvasive Raman spectroscopy in living mice for evaluation of tumor targeting with carbon nanotubes NANO LETTERS Zavaleta, C., de la Zerda, A., Liu, Z., Keren, S., Cheng, Z., Schipper, M., Chen, X., Dai, H., Gambhir, S. S. 2008; 8 (9): 2800-2805

    Abstract

    An optimized noninvasive Raman microscope was used to evaluate tumor targeting and localization of single walled carbon nanotubes (SWNTs) in mice. Raman images were acquired in two groups of tumor-bearing mice. The control group received plain-SWNTs, whereas the experimental group received tumor targeting RGD-SWNTs intravenously. Raman imaging commenced over the next 72 h and revealed increased accumulation of RGD-SWNTs in tumor ( p < 0.05) as opposed to plain-SWNTs. These results support the development of a new preclinical Raman imager.

    View details for DOI 10.1021/nl801362a

    View details for Web of Science ID 000259140200034

    View details for PubMedID 18683988

  • Carbon nanotubes as photoacoustic molecular imaging agents in living mice NATURE NANOTECHNOLOGY de la Zerda, A., Zavaleta, C., Keren, S., Vaithilingam, S., Bodapati, S., Liu, Z., Levi, J., Smith, B. R., Ma, T., Oralkan, O., Cheng, Z., Chen, X., Dai, H., Khuri-Yakub, B. T., Gambhir, S. S. 2008; 3 (9): 557-562

    Abstract

    Photoacoustic imaging of living subjects offers higher spatial resolution and allows deeper tissues to be imaged compared with most optical imaging techniques. As many diseases do not exhibit a natural photoacoustic contrast, especially in their early stages, it is necessary to administer a photoacoustic contrast agent. A number of contrast agents for photoacoustic imaging have been suggested previously, but most were not shown to target a diseased site in living subjects. Here we show that single-walled carbon nanotubes conjugated with cyclic Arg-Gly-Asp (RGD) peptides can be used as a contrast agent for photoacoustic imaging of tumours. Intravenous administration of these targeted nanotubes to mice bearing tumours showed eight times greater photoacoustic signal in the tumour than mice injected with non-targeted nanotubes. These results were verified ex vivo using Raman microscopy. Photoacoustic imaging of targeted single-walled carbon nanotubes may contribute to non-invasive cancer imaging and monitoring of nanotherapeutics in living subjects.

    View details for DOI 10.1038/nnano.2008.231

    View details for Web of Science ID 000259013100014

    View details for PubMedID 18772918

  • Real-time intravital imaging of RGD-quantum dot binding to luminal endothelium in mouse tumor neovasculature NANO LETTERS Smith, B. R., Cheng, Z., De, A., Koh, A. L., Sinclair, R., Gambhir, S. S. 2008; 8 (9): 2599-2606

    Abstract

    Nanoscale materials have increasingly become subject to intense investigation for use in cancer diagnosis and therapy. However, there is a fundamental dearth in cellular-level understanding of how nanoparticles interact within the tumor environment in living subjects. Adopting quantum dots (qdots) for their excellent brightness, photostability, monodispersity, and fluorescent yield, we link arginine-glycine-aspartic acid (RGD) peptides to target qdots specifically to newly formed/forming blood vessels expressing alpha vbeta 3 integrins. Using this model nanoparticle system, we exploit intravital microscopy with subcellular ( approximately 0.5 microm) resolution to directly observe and record, for the first time, the binding of nanoparticle conjugates to tumor blood vessels in living subjects. This generalizable method enabled us to show that in this model qdots do not extravasate and, unexpectedly, that they only bind as aggregates rather than individually. This level of understanding is critical on the path toward ensuring regulatory approval of nanoparticles in humans for disease diagnostics and therapeutics. Equally vital, the work provides a platform by which to design and optimize molecularly targeted nanoparticles including quantum dots for applications in living subjects.

    View details for DOI 10.1021/nl80141f

    View details for Web of Science ID 000259140200001

    View details for PubMedID 18386933

  • Direct site-specific radiolabeling of an Affibody protein with 4-[18F]fluorobenzaldehyde via oxime chemistry. Molecular imaging and biology Namavari, M., Padilla De Jesus, O., Cheng, Z., De, A., Kovacs, E., Levi, J., Zhang, R., Hoerner, J. K., Grade, H., Syud, F. A., Gambhir, S. S. 2008; 10 (4): 177-181

    Abstract

    In this study, we introduce a methodology for preparing 18F-labeled Affibody protein, specifically 18F-Anti-HER2 dimeric Affibody (14 kDa), for in vivo imaging of HER2neu with positron emission tomography (PET).We have used 4-[18F]fluorobenzaldehyde as a synthon to prepare 18F-Anti-HER2 Affibody. Aminooxy-functionalized Affibody (Anti-HER2-ONH2) was incubated with 4-[18F]fluorobenzaldehyde in ammonium acetate buffer at pH 4 in the presence of methanol at 70 degrees C for 15 min. The resulting 18F-labeled Affibody molecule was evaluated as a PET probe in xenograft models expressing HER2.We have successfully prepared 18F-Anti-HER2 dimeric Affibody (14 kDa), N-(4-[18F]fluorobenzylidine)oxime-Anti-HER2 Affibody, [18F]FBO-Anti-HER2, in 26-30% radiochemical yields (decay corrected). High-contrast small-animal PET images with relatively moderate tumor uptake (1.79 +/- 0.40% ID/g) were observed for the 18F-Anti-HER2 Affibody.Site-specific 18F-labeled Affibody against HER2 has been synthesized via chemoselective oxime formation between an aminooxy-functionalized Affibody and 18F-fluorobenzaldehyde. The results have implications for radiolabeling of other affibodies and macromolecules and should also be important for advancing Affibody imaging with PET.

    View details for DOI 10.1007/s11307-008-0142-7

    View details for PubMedID 18481153

  • Small-animal PET Imaging of human epidermal growth factor receptor type 2 expression with site-specific F-18-labeled protein scaffold molecules JOURNAL OF NUCLEAR MEDICINE Cheng, Z., De Jesus, O. P., Namavari, M., De, A., Levi, J., Webster, J. M., Zhang, R., Lee, B., Syud, F. A., Gambhir, S. S. 2008; 49 (5): 804-813

    Abstract

    Human epidermal growth factor receptor type 2 (HER2) is a well-established tumor biomarker that is overexpressed in a wide variety of cancers and that serves as a molecular target for therapeutic intervention. HER2 also serves as a prognostic indicator of patient survival and as a predictive marker of the response to antineoplastic therapy. The development of (18)F-labeled biomolecules for PET imaging of HER2 (HER2 PET) is very important because it may provide a powerful tool for the early detection of HER2-positive tumor recurrence and for the monitoring of HER2-based tumor treatment.In this study, anti-HER2 monomeric and dimeric protein scaffold molecules [Z(HER2:477) and (Z(HER2:477))(2), respectively] were radiofluorinated at a reasonable radiochemical yield (13%-18%) by use of site-specific oxime chemistry. The resulting radiofluorinated protein scaffold molecules were then evaluated as potential molecular probes for small-animal HER2 PET by use of a SKOV3 tumor-bearing mouse model.The 4-(18)F-fluorobenzaldehyde conjugated aminooxy-protein scaffolds [(18)F-N-(4-fluorobenzylidene)oxime (FBO)-Z(HER2:477) and (18)F-FBO-(Z(HER2:477))(2)] both displayed specific HER2-binding ability in vitro. Biodistribution and small-animal PET imaging studies further revealed that (18)F-FBO-Z(HER2:477) showed rapid and high SKOV3 tumor accumulation and quick clearance from normal tissues, whereas (18)F-FBO-(Z(HER2:477))(2) showed poor in vivo performance (low tumor uptake and tumor-to-normal tissue ratios). The specificity of (18)F-FBO-Z(HER2:477) for SKOV3 tumors was confirmed by its lower uptake on pretreatment of tumor-bearing mice with the HER2-targeting agents Z(HER2) and trastuzumab. Moreover, small-animal PET imaging studies revealed that (18)F-FBO-Z(HER2:477) produced higher-quality tumor imaging than (18)F-FBO-(Z(HER2:477))(2). (18)F-FBO-Z(HER2:477) could clearly identify HER2-positive tumors with good contrast.Overall, these data demonstrate that (18)F-FBO-Z(HER2:477) is a promising PET probe for imaging HER2 expression in living mice. It has a high potential for translation to clinical applications. The radiofluorination method developed can also be used as a general strategy for the site-specific labeling of other proteins with (18)F. The protein scaffold molecules used here are attractive for the further development of PET probes for other molecular targets.

    View details for DOI 10.2967/jnumed.107.047381

    View details for Web of Science ID 000255809100032

    View details for PubMedID 18413392

  • Noninvasive molecular imaging of small living subjects using Raman spectroscopy PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Keren, S., Zavaleta, C., Cheng, Z., de la Zerda, A., Gheysens, O., Gambhir, S. S. 2008; 105 (15): 5844-5849

    Abstract

    Molecular imaging of living subjects continues to rapidly evolve with bioluminescence and fluorescence strategies, in particular being frequently used for small-animal models. This article presents noninvasive deep-tissue molecular images in a living subject with the use of Raman spectroscopy. We describe a strategy for small-animal optical imaging based on Raman spectroscopy and Raman nanoparticles. Surface-enhanced Raman scattering nanoparticles and single-wall carbon nanotubes were used to demonstrate whole-body Raman imaging, nanoparticle pharmacokinetics, multiplexing, and in vivo tumor targeting, using an imaging system adapted for small-animal Raman imaging. The imaging modality reported here holds significant potential as a strategy for biomedical imaging of living subjects.

    View details for DOI 10.1073/pnas.0710575105

    View details for Web of Science ID 000255237200036

    View details for PubMedID 18378895

  • The Application of Cleavable Linker in Development of Molecular Probe for Cancer Molecular Imaging. Recent Advances of Bioconjugate Chemistry in Molecular Imaging, Cheng Z, Levi J. 2008: 53-70
  • Bisdeoxycoelenterazine derivatives for improvement of bioluminescence resonance energy transfer assays JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Levi, J., De, A., Cheng, Z., Gambhir, S. S. 2007; 129 (39): 11900-?

    View details for DOI 10.1021/ja073936h

    View details for Web of Science ID 000249887700013

    View details for PubMedID 17850082

  • MicroPET-based biodistribution of quantum dots in living mice JOURNAL OF NUCLEAR MEDICINE Schipper, M. L., Cheng, Z., Lee, S., Bentolila, L. A., Iyer, G., Rao, J., Chen, X., Wu, A. M., Weiss, S., Gambhir, S. S. 2007; 48 (9): 1511-1518

    Abstract

    This study evaluates the quantitative biodistribution of commercially available CdSe quantum dots (QD) in mice.(64)Cu-Labeled 800- or 525-nm emission wavelength QD (21- or 12-nm diameter), with or without 2,000 MW (molecular weight) polyethylene glycol (PEG), were injected intravenously into mice (5.55 MBq/25 pmol QD) and studied using well counting or by serial microPET and region-of-interest analysis.Both methods show rapid uptake by the liver (27.4-38.9 %ID/g) (%ID/g is percentage injected dose per gram tissue) and spleen (8.0-12.4 %ID/g). Size has no influence on biodistribution within the range tested here. Pegylated QD have slightly slower uptake into liver and spleen (6 vs. 2 min) and show additional low-level bone uptake (6.5-6.9 %ID/g). No evidence of clearance from these organs was observed.Rapid reticuloendothelial system clearance of QD will require modification of QD for optimal utility in imaging living subjects. Formal quantitative biodistribution/imaging studies will be helpful in studying many types of nanoparticles, including quantum dots.

    View details for DOI 10.2967/jnumed.107.040071

    View details for Web of Science ID 000252894700039

    View details for PubMedID 17704240

  • Small-animal PET of melanocortin 1 receptor expression using a F-18-labeled alpha-melanocyte-stimulating hormone analog JOURNAL OF NUCLEAR MEDICINE Cheng, Z., Zhang, L., Graves, E., Xiong, Z., Dandekar, M., Chen, X., Gambhir, S. S. 2007; 48 (6): 987-994

    Abstract

    (18)F-Labeled small synthetic peptides have emerged as attractive probes for imaging various molecular targets with PET. The alpha-melanocyte-stimulating hormone (alpha-MSH) receptor (melanocortin type 1 receptor [MC1R]) is overexpressed in most murine and human melanomas. It is a promising molecular target for diagnosis and therapy of melanomas. However, (18)F compounds have not been successfully developed for imaging the MC1R.In this study, an alpha-MSH analog, Ac-Nle-Asp-His-D-Phe-Arg-Trp-Gly-Lys-NH(2) (NAPamide), was radiolabeled with N-succinimidyl-4-(18)F-fluorobenzoate ((18)F-SFB). The resulting radiopeptide was evaluated as a potential molecular probe for small-animal PET of melanoma and MC1R expression in melanoma xenografted mouse models.The binding affinity of (19)F-SFB-conjugated NAPamide, (19)F-FB-NAPamide, was determined to be 7.2 +/- 1.2 nM (mean +/- SD) using B16/F10 cells and (125)I-(Tyr(2))-[Nle(4),D-Phe(7)]-alpha-MSH [(125)I-(Tyr(2))-NDP] as a radioligand. The biodistribution of (18)F-FB-NAPamide was then investigated in C57BL/6 mice bearing subcutaneous murine B16/F10 melanoma tumors with high expression of MC1Rs and Fox Chase Scid mice bearing human A375M melanoma with a relatively low number of MC1R receptors. Biodistribution experiments showed that tumor uptake values (percentage injected dose per gram of tumor [%ID/g]) of (18)F-FB-NAPamide were 1.19 +/- 0.11 %ID/g and 0.46 +/- 0.11 %ID/g, in B16/F10 and A375M xenografted melanoma at 1 h after injection, respectively. Furthermore, the B16/F10 tumor uptake was significantly inhibited by coinjection with excess alpha-MSH peptide (P < 0.05), indicating that (18)F-FB-NAPamide specifically recognizes the MC1R in living mice. Small-animal PET of (18)F-FB-NAPamide in mice bearing B16/F10 and A375M tumors at 1 h after tail vein injection revealed good B16/F10 tumor-to-background contrast and low A375M tumor-to-background ratios.(18)F-FB-NAPamide is a promising molecular probe for alpha-MSH receptor-positive melanoma PET and warrants further study.

    View details for DOI 10.2967/jnumed.107.039602

    View details for Web of Science ID 000247054800024

    View details for PubMedID 17504880

  • Fluorescent fructose derivatives for imaging breast cancer cells BIOCONJUGATE CHEMISTRY Levi, J., Cheng, Z., Gheysens, O., Patel, M., Chan, C. T., Wang, Y., Namavari, M., Gambhir, S. S. 2007; 18 (3): 628-634

    Abstract

    Breast cancer cells are known to overexpress Glut5, a sugar transporter responsible for the transfer of fructose across the cell membrane. Since Glut5 transporter is not significantly expressed in normal breast cells, fructose uptake can potentially be used to differentiate between normal and cancerous cells. Fructose was labeled with two fluorophores at the C-1 position: 7-nitro-1,2,3-benzadiazole (NBD) and Cy5.5. The labeling site was chosen on the basis of the presence and substrate specificity of the key proteins involved in the first steps of fructose metabolism. Using fluorescence microscopy, the uptake of the probes was studied in three breast cancer cell lines: MCF 7, MDA-MB-435, and MDA-MB-231. Both fluorescent fructose derivatives showed a very good uptake in all tested cell lines. The level of uptake was comparable to that of the corresponding glucose analogs, 2-NBDG and Cy5.5-DG. Significant uptake of 1-NBDF derivative was not observed in cells lacking Glut5 transporter, while the uptake of the 1-Cy5.5-DF derivative was independent of the presence of a fructose-specific transporter. While 1-NBDF showed Glut5-specific accumulation, the coupling of a large fluorophore such as Cy5.5 likely introduces big structural and electronic changes, leading to a fructose derivative that does not accurately describe the uptake of fructose in cells.

    View details for DOI 10.1021/bc060184s

    View details for Web of Science ID 000246485500005

    View details for PubMedID 17444608

  • Cu-64-Labeled alpha-melanocyte-stimulating hormone analog for MicroPET imaging of melanocortin 1 receptor expression BIOCONJUGATE CHEMISTRY Cheng, Z., Xiong, Z., Subbarayan, M., Chen, X., Gambhir, S. S. 2007; 18 (3): 765-772

    Abstract

    The alpha-melanocyte-stimulating hormone (alpha-MSH) receptor (melanocortin type 1 receptor, or MC1R) plays an important role in the development and growth of melanoma cells. It was found that MC1R was overexpressed on most murine and human melanoma, making it a promising molecular target for melanoma imaging and therapy. Radiolabeled alpha-MSH peptide and its analogs that can specifically bind with MC1R have been extensively explored for developing novel agents for melanoma detection and radionuclide therapy. The goal of this study was to evaluate a 64Cu-labeled alpha-MSH analog, Ac-Nle-Asp-His-D-Phe-Arg-Trp-Gly-Lys(DOTA)-NH2 (DOTA-NAPamide), as a potential molecular probe for microPET imaging of melanoma and MC1R expression in melanoma xenografted mouse models. 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugated NAPamide was synthesized and radiolabeled with 64Cu (t1/2=12 h) in NH4OAc (0.1 M; pH 5.5) buffered solution for 60 min at 50 degrees C. Cell culture studies reveal rapid and high uptake and internalization of 64Cu-DOTA-NAPamide in B16F10 cells. Over 90% of receptor-bound tracer is internalized at 3 h incubation. A cellular retention study demonstrates that the receptor-bound 64Cu-DOTA-NAPamide is slowly released from the B16F10 cells into the medium; 66% of the radioactivity is still associated with the cells even after 3 h incubation. The biodistribution of 64Cu-DOTA-NAPamide was then investigated in C57BL/6 mice bearing subcutaneous murine B16F10 melanoma tumors with high capacity of MC1R and Fox Chase Scid mice bearing human A375M melanoma with a relatively low number of MC1R receptors. Tumor uptake values of 64Cu-DOTA-NAPamide are found to be 4.63 +/- 0.45% and 2.49 +/- 0.31% ID/g in B16F10 and A375M xenografted melanoma at 2 h postinjection (pi), respectively. The B16F10 tumor uptake at 2 h pi is further inhibited to 2.29 +/- 0.24% ID/g, while A375M tumor uptake at 2 h pi remains 2.20 +/- 0.41% ID/g with a coinjection of excess alpha-MSH peptide. MicroPET imaging of 64Cu-DOTA-NAPamide in B16F10 tumor mice clearly shows good tumor localization. However, low A375M tumor uptake and poor tumor to normal tissue contrast were observed. This study demonstrates that 64Cu-DOTA-NAPamide is a promising molecular probe for alpha-MSH receptor positive melanoma PET imaging as well as MC1R expression imaging in living mice.

    View details for DOI 10.1021/bc060306g

    View details for Web of Science ID 000246485500021

    View details for PubMedID 17348700

  • In vivo bioluminescence tumor imaging of RGD peptide-modified adenoviral vector encoding firefly luciferase reporter gene MOLECULAR IMAGING AND BIOLOGY Niu, G., Xiong, Z., Cheng, Z., Cai, W., Gambhir, S. S., Xing, L., Chen, X. 2007; 9 (3): 126-134

    Abstract

    The goal of this study is to demonstrate the feasibility of chemically modified human adenovirus (Ad) vectors for tumor retargeting.E1- and E3-deleted Ad vectors carrying firefly luciferase reporter gene under cytomegalovirus promoter (AdLuc) was surface-modified with cyclic arginine-glycine-aspartic acid (RGD) peptides through a bifunctional poly(ethyleneglycol) linker (RGD-PEG-AdLuc) for integrin alpha(v)beta(3) specific delivery. The Coxsackie and adenovirus viral receptor (CAR) and integrin alpha(v)beta(3) expression in various tumor cell lines was determined by reverse transcriptase PCR and fluorescence-activated cell sorting. Bioluminescence imaging was performed in vitro and in vivo to evaluate RGD-modified AdLuc infectivity.RGD-PEG-AdLuc abrogated the native CAR tropism and exhibited significantly enhanced transduction efficiency of integrin-positive tumors than AdLuc through intravenous administration.This approach provides a robust platform for site-specific gene delivery and noninvasive monitoring of the transgene delivery efficacy and homing.

    View details for DOI 10.1007/s11307-007-0079-2

    View details for Web of Science ID 000246175500005

    View details for PubMedID 17297551

  • Near-infrared fluorescent deoxyglucose analogue for tumor optical imaging in cell culture and living mice BIOCONJUGATE CHEMISTRY Cheng, Z., Levi, J., Xiong, Z., Gheysens, O., Keren, S., Chen, X., Gambhir, S. S. 2006; 17 (3): 662-669

    Abstract

    2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) has extensively been used for clinical diagnosis, staging, and therapy monitoring of cancer and other diseases. Nonradioactive glucose analogues enabling the screening of the glucose metabolic rate of tumors are of particular interest for anticancer drug development. A nonradioactive fluorescent deoxyglucose analogue may have many applications for both imaging of tumors and monitoring therapeutic efficacy of drugs in living animals and may eventually translate to clinical applications. We found that a fluorescent 2-deoxyglucose analogue, 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose (2-NBDG), can be delivered in several tumor cells via the glucose transporters (GLUTs). We therefore conjugated D-glucosamine with a near-infrared (NIR) fluorphor Cy5.5 and tested the feasibility of the Cy5.5-D-glucosamine (Cy5.5-2DG) conjugate for NIR fluorescence imaging of tumors in a preclinical xenograft animal model. Cy5.5-2DG was prepared by conjugating Cy5.5 monofunctional N-hydroxysuccinimide ester (Cy5.5-NHS) and D-glucosamine followed by high-performance liquid chromatography purification. The accumulation of Cy5.5-2DG and Cy5.5-NHS in different tumor cell lines at 37 and 4 degrees C were imaged using a fluorescence microscope. Tumor targeting and retention of Cy5.5-2DG and Cy5.5-NHS in a subcutaneous U87MG glioma and A375M melanoma tumor model were evaluated and quantified by a Xenogen IVIS 200 optical cooled charged-coupled device system. Fluorescence microscopy imaging shows that Cy5.5-2DG and Cy5.5-NHS are taken up and trapped by a variety of tumor cell lines at 37 degrees C incubation, while they exhibit marginal uptake at 4 degrees C. The tumor cell uptake of Cy5.5-2DG cannot be blocked by the 50 mM D-glucose, suggesting that Cy5.5-2DG may not be delivered in tumor cells by GLUTs. U87MG and A375M tumor localization was clearly visualized in living mice with both NIR fluorescent probes. Tumor/muscle contrast was clearly visible as early as 30 min postinjection (pi), and the highest U87MG tumor/muscle ratios of 2.81 +/- 0.10 and 3.34 +/- 0.23 were achieved 24 h pi for Cy5.5-2DG and Cy5.5-NHS, respectively. While as a comparison, the micropositron emission tomography imaging study shows that [18F]FDG preferentially localizes to the U87MG tumor, with resulting tumor/muscle ratios ranging from 3.89 to 4.08 after 30 min to 2 h postadministration of the probe. In conclusion, the NIR fluorescent glucose analogues, Cy5.5-2DG and Cy5.5-NHS, both demonstrate tumor-targeting abilities in cell culture and living mice. More studies are warranted to further explore their application for optical tumor imaging. To develop NIR glucose analogues with the ability to target GLUTs/hexokinase, it is highly important to select NIR dyes with a reasonable molecular size.

    View details for DOI 10.1021/bc050345c

    View details for Web of Science ID 000237576000013

    View details for PubMedID 16704203

  • Imaging chemically modified adenovirus for targeting tumors expressing integrin alpha(v)beta(3) in living mice with mutant herpes simplex virus type 1 thymidine kinase PET reporter gene JOURNAL OF NUCLEAR MEDICINE Xiong, Z. M., Cheng, Z., Zhang, X. Z., Patel, M., Wu, J. C., Gambhir, S. S., Chen, X. Y. 2006; 47 (1): 130-139

    Abstract

    The aim of this study was to change adenovirus tropism by chemical modification of the fiber knobs with PEGylated RGD peptide for targeting integrin alpha(v)beta(3) that is uniquely or highly expressed in tumor cells and neovasculature of tumors of various origins.The first generation Ad (Ad) vector, which expresses the herpes simplex virus type 1 mutant thymidine kinase (HSV1-sr39tk) gene under the control of cytomegalovirus (CMV) promoter was conjugated with poly(ethylene glycol) (PEG) or RGD-PEG. The transduction efficiency of Ads (Adtk, PEG-Adtk, and RGD-PEG-Adtk) into different types of cells (293T, MCF7, MDA-MB-435, and U87MG) was analyzed and quantified by thymidine kinase (TK) assay using 8-(3)H-penciclovir (8-(3)H-PCV) as substrate. The in vivo infectivity of the Ad vectors after intravenous administration into integrin alpha(v)beta(3)-positive U87MG and MDA-MB-435 tumor-bearing athymic nude mice was measured by both noninvasive microPET using 9-[4-(18)F-fluoro-3-(hydroxymethyl)butyl]guanine ((18)F-FHBG) as a reporter probe and ex vivo TK assay of the tumor and tissue homogenates.PEGylation completely abrogated coxsackievirus and adenovirus receptor (CAR)-knob interaction and the infectivity of PEG-Adtk is significantly lower than that of unmodified Adtk in CAR-positive cells. RGD-PEG-modified virus (RGD-PEG-Adtk) had significantly higher infectivity than PEG-Adtk and the extent of increase is related to both CAR and integrin alpha(v)beta(3) expression levels. (18)F-FHBG had minimal nonspecific uptake in the liver and tumors that are void of sr39tk. Mice preinjected intravenously with unmodified Adtk resulted in high hepatic uptake and moderate tumor accumulation of the tracer. In contrast, RGD-PEG-Adtk administration resulted in significantly lower liver uptake without compromising the tumor accumulation of (18)F-FHBG. Expression of TK in the liver and tumor homogenates corroborated with the magnitude of (18)F-FHBG uptake quantified by noninvasive microPET. Analysis of liver and tumor tissue integrin level confirmed that RGD-integrin interaction is responsible for the enhanced tumor infectivity of RGD-PEG-Adtk.The results of this study suggest that RGD-PEG conjugation is an effective way to modify Ad vector tropism for improved systemic gene delivery. Noninvasive PET and (18)F-FHBG are able to monitor in vivo transfectivity of both Adtk and RGD-PEG-Adtk vectors in the liver and tumors after intravenous injection.

    View details for Web of Science ID 000234679300024

    View details for PubMedID 16391197

  • Reproducibility of 3 '-deoxy-3 '-F-18-fluorothymidine MicroPET studies in tumor xenografts in mice JOURNAL OF NUCLEAR MEDICINE Tseng, J. R., Dandekar, M., Subbarayan, M., Cheng, Z., Park, J. M., Louie, S., Gambhir, S. S. 2005; 46 (11): 1851-1857

    Abstract

    3'-Deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) has been used to image tumor proliferation in preclinical and clinical studies. Serial microPET studies may be useful for monitoring therapy response or for drug screening; however, the reproducibility of serial scans has not been determined. The purpose of this study was to determine the reproducibility of (18)F-FLT microPET studies.C6 rat glioma xenografts were implanted into nude mice (n = 9) and grown to mean diameters of 5-17 mm for approximately 2 wk. A 10-min acquisition was performed on a microPET scanner approximately 1 h after (18)F-FLT (1.9-7.4 MBq [50-200 muCi]) was injected via the tail vein. A second microPET scan was performed approximately 6 h later on the same day after reinjection of (18)F-FLT to assess for reproducibility. Most of the mice were studied twice within the same week (for a total of 17 studies). Images were analyzed by drawing an ellipsoidal region of interest (ROI) around the tumor xenograft activity. Percentage injected dose per gram (%ID/g) values were calculated from the mean activity in the ROIs. Coefficients of variation and differences in %ID/g values between studies from the same day were calculated to determine the reproducibility after subtraction of the estimated residual tumor activity from the first (18)F-FLT injection.The coefficient of variation (mean +/- SD) for %ID/g values between (18)F-FLT microPET scans performed 6 h apart on the same day was 14% +/- 10%. The difference in %ID/g values between scans was -0.06% +/- 1.3%. Serum thymidine levels were mildly correlated with %ID/g values (R(2) = 0.40). Tumor size, mouse body weight, injected dose, and fasting state did not contribute to the variability of the scans; however, consistent scanning parameters were necessary to ensure accurate studies, in particular, controlling body temperature, the time of imaging after injection, and the ROI size.(18)F-FLT microPET mouse tumor xenograft studies are reproducible with moderately low variability. Serial studies may be performed to assess for significant changes in therapy response or for preclinical drug development.

    View details for Web of Science ID 000233095800017

    View details for PubMedID 16269599

  • Near-infrared fluorescent RGD peptides for optical imaging of integrin alpha(v)beta 3 expression in living mice BIOCONJUGATE CHEMISTRY Cheng, Z., Wu, Y., Xiong, Z. M., Gambhir, S. S., Chen, X. Y. 2005; 16 (6): 1433-1441

    Abstract

    Near-infrared fluorescence optical imaging is a powerful technique for studying diseases at the molecular level in preclinical models. We recently reported that monomeric RGD peptide c(RGDyK) conjugated to the NIR fluorescent dye specifically targets integrin receptor both in cell culture and in living subjects. In this report, Cy5.5-conjugated mono-, di-, and tetrameric RGD peptides were evaluated in a subcutaneous U87MG glioblastoma xenograft model in order to investigate the effect of multimerization of RGD peptide on integrin avidity and tumor targeting efficacy. The binding affinities of Cy5.5-conjugated RGD monomer, dimer, and tetramer for alpha(v)beta(3) integrin expressed on U87MG cell surface were determined to be 42.9 +/- 1.2, 27.5 +/- 1.2, and 12.1 +/- 1.3 nmol/L, respectively. All three peptide-dye conjugates had integrin specific uptake both in vitro and in vivo. The subcutaneous U87MG tumor can be clearly visualized with each of these three fluorescent probes. Among them, tetramer displayed highest tumor uptake and tumor-to-normal tissue ratio from 0.5 to 4 h postinjection. Tumor-to-normal tissue ratio for Cy5.5-conjugated RGD monomer, dimer, and tetramer were found to be 3.18 +/- 0.16, 2.98 +/- 0.05, and 3.63 +/- 0.09, respectively, at 4 h postinjection. These results suggest that Cy5.5-conjugated monomeric, dimeric, and tetrameric RGD peptides are all suitable for integrin expression imaging. The multmerization of RGD peptide results in moderate improvement of imaging characteristics of the tetramer, compared to that of the monomer and dimeric counterparts.

    View details for DOI 10.1021/bc0501698

    View details for Web of Science ID 000233393800015

    View details for PubMedID 16287239

  • microPET imaging of glioma integrin alpha(V)beta(3) expression using Cu-64-labeled tetrameric RGD peptide JOURNAL OF NUCLEAR MEDICINE Wu, Y., Zhang, X. Z., Xiong, Z. M., Cheng, Z., Fisher, D. R., Liu, S., Gambhir, S. S., Chen, X. Y. 2005; 46 (10): 1707-1718

    Abstract

    Integrin alpha(v)beta(3) plays a critical role in tumor-induced angiogenesis and metastasis and has become a promising diagnostic indicator and therapeutic target for various solid tumors. Radiolabeled RGD peptides that are integrin specific can be used for noninvasive imaging of integrin expression level as well as for integrin-targeted radionuclide therapy.In this study we developed a tetrameric RGD peptide tracer (64)Cu-DOTA-E{E[c(RGDfK)](2)}(2) (DOTA is 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) for PET imaging of integrin alpha(v)beta(3) expression in female athymic nude mice bearing the subcutaneous UG87MG glioma xenografts.The RGD tetramer showed significantly higher integrin binding affinity than the corresponding monomeric and dimeric RGD analogs, most likely due to a polyvalency effect. The radiolabeled peptide showed rapid blood clearance (0.61 +/- 0.01 %ID/g at 30 min and 0.21 +/- 0.01 %ID/g at 4 h after injection, respectively [%ID/g is percentage injected dose per gram]) and predominantly renal excretion. Tumor uptake was rapid and high, and the tumor washout was slow (9.93 +/- 1.05 %ID/g at 30 min after injection and 4.56 +/- 0.51 %ID/g at 24 h after injection). The metabolic stability of (64)Cu-DOTA-E{E[c(RGDfK)](2)}(2) was determined in mouse blood, urine, and liver and kidney homogenates at different times after tracer injection. The average fractions of intact tracer in these organs at 1 h were approximately 70%, 58%, 51%, and 26%, respectively. Noninvasive microPET studies showed significant tumor uptake and good contrast in the subcutaneous tumor-bearing mice, which agreed well with the biodistribution results. Integrin alpha(v)beta(3) specificity was demonstrated by successful blocking of tumor uptake of (64)Cu-DOTA-E{E[c(RGDfK)](2)}(2) in the presence of excess c(RGDyK) at 1 h after injection. The highest absorbed radiation doses determined for the human reference adult were received by the urinary bladder wall (0.262 mGy/MBq), kidneys (0.0296 mGy/MBq), and liver (0.0242 mGy/MBq). The average effective dose resulting from a single (64)Cu-DOTA-E{E[c(RGDfK)](2)}(2) injection was estimated to be 0.0164 mSv/MBq.The high integrin and avidity and favorable biokinetics make (64)Cu-DOTA-E{E[c(RGDfK)](2)}(2) a promising agent for peptide receptor radionuclide imaging and therapy of integrin-positive tumors.

    View details for Web of Science ID 000232452700033

    View details for PubMedID 16204722

  • [99(m)TcOAADT]-(CH2)(2)-NEt2: A potential small-molecule single-photon emission computed tomography probe for Imaging metastatic melanoma CANCER RESEARCH Cheng, Z., Mahmood, A., Li, H. Z., Davison, A., Jones, A. G. 2005; 65 (12): 4979-4986

    Abstract

    Evaluation of [99mTc]oxotechnetium(V) complexes of the amine-amide-dithiol (AADT) chelates containing tertiary amine substituents as small-molecule probes for the diagnostic imaging of metastatic melanoma has shown that technetium-99m-labeled AADT-(CH2)2-NEt2 (99mTc-1) has the highest tumor uptake and other favorable biological properties. We have, therefore, assessed this agent in a more realistic metastatic melanoma model in which, after i.v. tail injection, a highly invasive melanoma cell line, B16F10, forms pulmonary tumor nodules in normal C57BL6 mice. Small melanotic lesions develop in the lungs and, on histologic examination, appear as small black melanoma colonies, increasing in size and number with time after tumor cell injection. Groups of mice received tumor cell inocula of 2 x 10(5), 4 x 10(5), or 8 x 10(5) B16F10 cells; 14 days later, 2 hours after 99mTc-1 administration, lung uptake of 2.83 +/- 0.21%, 3.63 +/- 1.07%, and 4.92 +/- 1.61% injected dose per gram of tissue (% ID/g), respectively, was observed, compared with normal lung uptake of 2.13 +/- 0.2% ID/g (P < 0.05). Additionally, a higher level of 99mTc-1 accumulation was seen 17 days after tumor cell inoculation as the lung lesions grew. These in vivo studies coupled with additional in vitro and ex vivo assessment show that 99mTc-1 has high and specific uptake in melanoma metastases in lungs and can potentially follow the temporal growth of these tumors.

    View details for Web of Science ID 000229734300003

    View details for PubMedID 15958536

  • A new strategy to screen molecular imaging probe uptake in cell culture without radiolabeling using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry JOURNAL OF NUCLEAR MEDICINE Cheng, Z., Winant, R. C., Gambhir, S. S. 2005; 46 (5): 878-886

    Abstract

    Numerous new molecular targets for diseases are rapidly being identified and validated in the postgenomic era, urging scientists to explore novel techniques for accelerating molecular probe development. In this study, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was investigated as a potential tool for high-throughput screening and characterization of molecular imaging probes. Specifically, MALDI-TOF-MS was used to screen a small library of phosphonium cations for their ability to accumulate in cells.C6 cells incubated with phosphonium cations at room temperature were collected and lysed for experiments. Calibration curves for the internal standard, methyltriphenyl phosphonium, and for tetraphenylphosphonium bromide (TPP) and other phosphonium cations were first established. The time course of TPP uptake by C6 cells was then quantified using both MALDI-TOF-MS and liquid scintillation counting with (3)H-TPP. In addition, MALDI-TOF-MS was used to screen a library of 8 phosphonium cations and subsequently rank their ability to penetrate membranes and accumulate in cells. Finally, the accumulation of 4-fluorophenyltriphenyl phosphonium (FTPP) in the membrane potential-modulated cells was also measured by MALDI-TOF-MS.MALDI-TOF-MS spectra clearly revealed that TPP was easily identified from cell lysates even as early as 10 min after incubation and that levels as low as 0.11 fmol of TPP per cell could be detected, suggesting the high sensitivity of this technique. The time course of TPP influx determined by both MALDI-TOF-MS and radioactivity counting showed no statistically significant difference (P > 0.05 for all time points). These data validated MALDI-TOF-MS as an alternative approach for accurately measuring uptake of phosphonium cations by cells. TPP and FTPP demonstrated greater accumulation in cells than did the other cations evaluated in this study. Furthermore, uptake profiles suggested that FTPP preserves the membrane potential-dependent uptake property of TPP in cell cultures. Taken together, these data justify further synthesis and evaluation of (18)F-FTPP as a molecular probe for imaging mitochondrial dysfunction.These results demonstrate that MALDI-TOF-MS is a powerful analytic tool for rapid screening and characterization of phosphonium cations as molecular probes. This technique can potentially be applied to the evaluation of other imaging probes or drugs and thus may facilitate their rational design and development.

    View details for Web of Science ID 000228952400030

    View details for PubMedID 15872363

  • Synthesis of (4-[F-18]fluorophenyl)triphenylphosphonium as a potential imaging agent for mitochondrial dysfunction JOURNAL OF LABELLED COMPOUNDS & RADIOPHARMACEUTICALS Cheng, Z., Subbarayan, M., Chen, X. Y., Gambhir, S. S. 2005; 48 (2): 131-137

    View details for DOI 10.1002/jlcr.906

    View details for Web of Science ID 000227120300006

  • Synthesis of (4-[18F]fluorophenyl)-triphenylphosphonium as a potential imaging agent for mitochondrial dysfunction. Journal of Labelled Compound & Radiopharmaceuticals Cheng Z, Subbarayan M, Chen X, Gambhir SS. 2005; 48: 131-137
  • Radioiodination of rhenium cyclized alpha-melanocyte-stimulating hormone resulting in enhanced radioactivity localization and retention in melanoma CANCER RESEARCH Cheng, Z., Chen, J. Q., Quinn, T. P., Jurisson, S. S. 2004; 64 (4): 1411-1418

    Abstract

    Radiohalogenated alpha-melanocyte-stimulating hormone (alpha-MSH) analogs were proposed for melanoma imaging and potential radiotherapy because alpha-MSH receptors are overexpressed on both mouse and human melanoma cell lines. However, biodistribution studies in tumor-bearing mice with radiohalogenated alpha-MSH peptides showed very rapid tumor radioactivity wash out due to lysosomal degradation of the radiohalogenated complex after internalization, which decreased the therapeutic efficacy significantly (R. Stein et al., Cancer Res., 55: 3132-3139, 1995; P. K. Garg et al., Bioconjugate Chem., 6: 493-501, 1995.). The melanoma-targeting metallopeptide ReO[Cys(3,4,10),D-Phe(7)]alpha-MSH(3-13) (ReCCMSH) was shown to possess high tumor uptake and retention properties (J. Chen et al., Cancer Res., 60: 5649-5658, 2000). Therefore, three peptides, Ac-Lys-ReCCMSH(Arg(11)), Ac-D-Lys-ReCCMSH(Arg(11)), and [Nle(4),D-Phe(7)]alpha-MSH (NDP) (for comparison), labeled with N-succinimidyl 4-[(125)I]iodobenzoate ((125)I-PIB), were prepared and evaluated in vitro and in vivo to develop radiohalogenated alpha-MSH peptide analogs with high tumor uptake, retention, and favorable biodistribution characteristics. In vitro cell binding and internalization data showed that approximately 90% of radioiodinated peptides were internalized at 2 h in cultured B16/F1 melanoma cells. Cellular retention studies showed that the receptor-bound radioiodinated linear alpha-MSH analog NDP was released from the cells into the medium very quickly, whereas significant amounts of cell-associated radioactivity remained in the cells for Ac-Lys((125)I-3- or 4-iodobenzoate (IBA))-ReCCMSH(Arg(11)) and Ac-D-Lys((125)I-IBA)-ReCCMSH(Arg(11)). The in vitro data clearly demonstrate that rhenium cyclization significantly enhanced peptide trapping in the cells, as did D-amino acid incorporation. The combination of these two effects resulted in a 2.9-fold increase in the retention of radioactivity for Ac-D-Lys((125)I-IBA)-ReCCMSH(Arg(11)) relative to (125)I-IBA-NDP at 4 h. In vivo studies also showed that Ac-D-Lys((125)I-IBA)-ReCCMSH(Arg(11)) exhibited extremely high radioactivity accumulation and prolonged retention in the tumor. Ac-D-Lys((125)I-IBA)-ReCCMSH(Arg(11)) and Ac-Lys((125)I-IBA)-ReCCMSH(Arg(11)) exhibited much higher tumor uptake at 24 h after injection compared with (125)I-IBA-NDP [7.18% injected dose/gram (ID/g), 4.92% ID/g, and 0.26% ID/g, respectively]. Ac-D-Lys((125)I-IBA)-ReCCMSH(Arg(11)) also showed very fast whole body clearance and low nonspecific radioactivity accumulation in normal tissues compared with (125)I-IBA-NDP and Ac-Lys((125)I-IBA)-ReCCMSH(Arg(11)). A tumor:blood ratio of 34.3 was observed for Ac-D-Lys((125)I-IBA)-ReCCMSH(Arg(11)) at 24 h postinjection, whereas values of 4.3 and 2.0 were observed for Ac-Lys((125)I-IBA)-ReCCMSH(Arg(11)) and (125)I-IBA-NDP, respectively. The biodistribution data clearly demonstrate that both rhenium cyclization and D-Lys incorporation enhanced the tumor localization and retention of the radiolabel. Therefore Ac-D-Lys-ReCCMSH(Arg(11)) is an excellent candidate for additional therapeutic studies.

    View details for Web of Science ID 000189245200029

    View details for PubMedID 14973076

  • Modification of the structure of a metallopeptide: Synthesis and biological evaluation of In-111-labeled DOTA-conjugated rhenium-cyclized alpha-MSH analogues JOURNAL OF MEDICINAL CHEMISTRY Cheng, Z., Chen, J. Q., Miao, Y. B., Owen, N. K., Quinn, T. P., Jurisson, S. S. 2002; 45 (14): 3048-3056

    Abstract

    Rhenium-cyclized CCMSH analogues are novel melanoma-targeting metallopeptides with high tumor uptake, long tumor retention, and low background in normal tissues, which make these metallopeptides an ideal structural motif for designing novel melanoma-targeting agents. ReCCMSH has been derivatized with a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) chelate so that it can be labeled with a wide variety of radionuclides for imaging and therapeutic applications. This study involved optimization of the in vivo biological properties of DOTA-ReCCMSH (S), through modification of the structure of the metallopeptide. Several DOTA-ReCCMSH analogues, Ac-Lys(DOTA)-ReCCMSH (4) DOTA-ReCCMSH(Arg(11)) (6), DOTA-ReCCMSH-OH (8), and DOTA-ReCCMSH-Asp-OH (10), were synthesized using solid phase peptide synthesis followed by rhenium cyclization. The IC(50) values of the metallopeptides were determined through competitive binding assays against (125)I-(Tyr(2))-NDP. Radiolabeling of the DOTA-rhenium-cyclized peptides with (111)In was carried out in NH(4)OAc (0.1 M; pH 5.5)-buffered solution for 30 min at 70 degrees C. The stability of the radiolabeled complexes was evaluated in 0.01 M, pH 7.4, phosphate-buffered saline/0.1% bovine serum albumin solution. After separation of the radiolabeled peptide from the unlabeled peptide by reverse phase high-performance liquid chromatography, the biodistribution of the radiolabeled complex was performed in C57 mice bearing B16/F1 murine melanoma tumors. All radiolabeled complexes showed fast blood clearance (2 h postinjection (pi): (111)In-S, 0.07 +/- 0.03% ID/g; (111)In-4, 0.09 +/- 0.06% ID/g; (111)In-6, 0.21 +/- 0.08% ID/g; (111)In-8, 0.11 +/- 0.10% ID/g; and (111)In-10, 0.05 +/- 0.03% ID/g), and their clearance was predominantly through the urine (4 h pi: 93.5 +/- 1.7, 87.8 +/- 6.5, 89.8 +/- 4.2, 93.3 +/- 1.1, and 93.8 +/- 1.8 (% ID) for (111)In-labeled S, 4, 6, 8, and 10, respectively). Tumor uptake values of 9.45 +/- 0.90, 6.01 +/- 2.36, 17.41 +/- 5.61, 9.27 +/- 0.68, and 7.32 +/- 2.09 (% ID/g) for (111)In-labeled S, 4, 6, 8, and 10, respectively, were observed at 4 h pi. The kidney uptake was 9.27 +/- 2.65% ID/g for (111)In-S, 19.02 +/- 2.63% ID/g for (111)In-4, 7.37 +/- 1.13% ID/g for (111)In-6, 8.70 +/- 0.88% ID/g for (111)In-8, and 8.13 +/- 1.47% ID/g for (111)In-10 at 4 h pi. Complex 6 showed high melanoma uptake and lower kidney uptake than the corresponding Lys(11) analogues, supporting 6 for further investigations as a potential therapeutic radiopharmaceutical.

    View details for DOI 10.1021/jm010408m

    View details for Web of Science ID 000176664900016

    View details for PubMedID 12086490

  • Differential in-vivo behavior of Tc(V)Oxo N2S2 complexes with melanoma affinity. Technetium, Rhenium and other Metals in Chemistry and Nuclear Medicine, Malago E, Mahmood A, Cheng Z, Kramer DJ, Friebe M, Eisenhut M, Davison A, Jones AG. 2002; 6: 419-421
  • Evaluation of [99mTcOAADT]-(CH2)2-N(Et)2 in a metastatic melanoma lung model. Technetium, Rhenium and other Metals in Chemistry and Nuclear Medicine, Cheng Z, M. L. 2002; 6: 423-425
  • Evaluation of an In-111-DOTA-rhenium cyclized alpha-MSH analog: A novel cyclic-peptide analog with improved tumor-targeting properties JOURNAL OF NUCLEAR MEDICINE Chen, J. Q., Cheng, Z., Owen, N. K., Hoffman, T. J., Miao, Y. B., Jurisson, S. S., Quinn, T. P. 2001; 42 (12): 1847-1855

    Abstract

    The aim of this study was to examine the effect of rhenium-mediated peptide cyclization on melanoma targeting, biodistribution, and clearance kinetics of the alpha-melanocyte-stimulating hormone (alpha-MSH) analog 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) coupled ReO-cyclized [Cys(3,4,10),D-Phe(7)]alpha-MSH(3-13) (DOTA-ReCCMSH).DOTA-ReCCMSH was compared with its reduced nonmetalated linear homolog, DOTA-CCMSH, and an analog in which rhenium cyclization was replaced by disulfide bond cyclization, DOTA-[Cys(4,10),D-Phe(7)]alpha-MSH(4-13) (CMSH). DOTA was also conjugated to the amino terminus of one of the highest-affinity alpha-MSH receptor-binding peptides, [Nle(4),D-Phe(7)]alpha-MSH (NDP), as a linear peptide standard. The DOTA-conjugated alpha-MSH analogs were radiolabeled with (111)In and examined for their in vitro receptor-binding affinity with B16/F1 murine melanoma cells, and their in vivo biodistribution properties were evaluated and compared in melanoma tumor-bearing C57 mice.The tumor uptake values of (111)In-DOTA-ReCCMSH were significantly higher than those of the other closely related (111)In-DOTA-alpha-MSH conjugates. Even at 24 h after injection, a comparison of the tumor uptake values for (111)In-DOTA-coupled ReCCMSH (4.86 +/- 1.52 percentage injected dose [%ID]/g), CCMSH (1.91 +/- 0.56 %ID/g), CMSH (3.09 +/- 0.32 %ID/g), and NDP (2.47 +/- 0.79 %ID/g) highlighted the high tumor retention property of ReCCMSH. Rhenium-coordinated cyclization resulted in less renal radioactivity accumulation of (111)In-DOTA-ReCCMSH (8.98 +/- 0.82 %ID/g) than of (111)In-DOTA-CCMSH (63.2 +/- 15.6 %ID/g), (111)In-DOTA-CMSH (38.4 +/- 3.6 %ID/g), and (111)In-DOTA-NDP (12.0 +/- 1.96 %ID/g) at 2 h after injection and significantly increased its clearance into the urine (92 %ID at 2 h after injection). A high radioactivity uptake ratio of tumor to normal tissue was obtained for (111)In-DOTA-ReCCMSH (e.g., 489, 159, 100, and 49 for blood, muscle, lung, and liver, respectively, at 4 h after injection).The novel ReO-coordinated cyclic structure of DOTA-ReCCMSH contributes significantly to its enhanced tumor-targeting and renal clearance properties and makes DOTAReCCMSH an excellent candidate for melanoma radiodetection and radiotherapy.

    View details for Web of Science ID 000172843200029

    View details for PubMedID 11752084

  • Melanoma-targeting properties of (99m)technetium-labeled cyclic alpha-melanocyte-stimulating hormone peptide analogues CANCER RESEARCH Chen, J. Q., Cheng, Z., Hoffman, T. J., Jurisson, S. S., Quinn, T. P. 2000; 60 (20): 5649-5658

    Abstract

    Preliminary reports have demonstrated that (99m)technetium (Tc)-labeled cyclic [Cys(3,4,10), D-Phe7]alpha-MSH(3-13) (CCMSH) exhibits high tumor uptake and retention values in a murine melanoma mouse model. In this report, the tumor targeting mechanism of 99mTc-CCMSH was studied and compared with four other radiolabeled alpha-melanocyte stimulating hormone (alpha-MSH) peptide analogues: 125I-(Tyr2)-[Nle4, D-Phe7]alpha-MSH [125I-(Tyr2)-NDP]; 99mTc-CGCG-NDP; 99mTc-Gly11-CCMSH; and 99mTc-Nle11-CCMSH. In vitro receptor binding, internalization, and cellular retention of radiolabeled alpha-MSH analogues in B16/F1 murine cell line demonstrated that >70% of the receptor-bound radiolabeled analogues were internalized together with the receptor. Ninety % of the internalized 125I-(Tyr2)-NDP, whereas only 36% of internalized 99mTc-CCMSH, was released from the cells into the medium during a 4-h incubation at 37 degrees C. Two mouse models, C57 mice and severe combined immunodeficient (Scid) mice, inoculated s.c. with B16/F1 murine and TXM-13 human melanoma cells were used for the in vivo studies. Tumor uptake values of 11.32 and 2.39 [% injected dose (ID)/g] for 99mTc-CCMSH at 4 h after injection, resulted in an uptake ratio of tumor:blood of 39.0 and 11.5 in murine melanoma-C57 and human melanoma-Scid mouse models, respectively. Two strategies for decreasing the nonspecific kidney uptake of 99mTc-CCMSH, substitution of Lys11 in CCMSH with Gly11 or Nle11, and lysine coinjection, were evaluated. The biodistribution data for the modified peptides showed that Lys11 replacement dramatically decreased the kidney uptake, whereas the tumor uptakes of 99mTc-Nle11- and 99mTc-Gly11-CCMSH were significantly lower than that of 99mTc-CCMSH. Lysine coinjection significantly decreased the kidney uptake (e.g., from 14.6% ID/g to 4.5% ID/g at 4 h after injection in murine melanoma-C57 mice) without significantly changing the value of tumor uptake of 99mTc-CCMSH. In conclusion, the compact cyclic structure of 99mTc-CCMSH, its resistance to degradation, and its enhanced intracellular retention are the major contributing factors to the superior in vivo tumor targeting properties of 99mTc-CCMSH. Lys11 residue in 99mTc-CCMSH is critical to the tumor targeting in vivo, and lysine coinjection rather than lysine replacement can significantly decrease the nonspecific renal radioactivity accumulation without impeding the high melanoma-targeting properties of 99Tc-CCMSH. The metal-cyclized CCMSH molecule displays excellent potential for the development of melanoma-specific diagnostic and therapeutic agents.

    View details for Web of Science ID 000090054800013

    View details for PubMedID 11059756

  • Quality control studies of Tc-99m-DTPA-octreotide by RP-HPLC J Radioanal Nucl Chem Cheng Z, L. J. 1998; 236: 97-101
  • Labeling conditions studies of Tyr3-octreotide with 131I and its biodistribution in mouse Journal of Isotopes Fan HQ, W. J. 1998; 11 (1): 29-33
  • HPLC analysis of radiolabeled octreotide. J Radioanal Nucl Chem Wang F, F. C. 1998; 236: 205-7
  • Preparation of Sm-153-resin micorosphere and determination of femoral head blood flow of rabbits. Journal of Isotopes Bai HS, C. J., Zhang NF, Yang L, Li ZR. 1998; 11 (1): 39-43
  • Study on analysis of Sm-153-EDTMP stability in vitro and in vivo by HPLC. J Radioanal Nucl Chem Bai HS, J. F. 1998; 236: 87-95
  • Labeling study on In-111-octreotide and primary animal tests. Journal of Isotopes Wang F, F. X. 1997; 10 (1): 16-20
  • Development of 99mTc-DTPA-octreotide somatostaton receptor imaging agent. I. studying of labeling conditions. Journal of Isotopes Cheng Z, Lin QF, Jin XH. 1997; 10 (3): 150-157
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  • Preparation of 166Ho-EDTMP-hydroxyapatite for radiation synovectomy. Nuclear Techniques Bai HS, Jin XH, Du J, Wang F, Chen DM, Fan HQ, Cheng Z. 1997; 20 (11): 691-695
  • Preliminary study on a potential tumor radiotherapy agent: 186Re(V)-DMSA. Journal of Isotopes. Chen DM, Jin XH, Du J, Wang F, Bai HS, Xu H, Cheng Z, Chen S, Qi X, Zhao X, Lu X. 1997; 10 (2): 109-112

Conference Proceedings


  • alpha-melanocyte-stimulating hormone peptide analogs labeled with technetium-99m and indium-111 for malignant melanoma targeting Chen, J. Q., Cheng, Z., Miao, Y. B., Jurisson, S. S., Quinn, T. P. JOHN WILEY & SONS INC. 2002: 1196-1201

    Abstract

    Previous studies have shown that the compact structure of a rhenium-cyclized alpha--melanocyte-stimulating hormone peptide analog, [Cys3410,D-Phe7]alpha-MSH(3--13), or Re-CCMSH, significantly enhanced its in vivo tumor uptake and retention. In this study, the metal chelate 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was coupled to the N-terminus of Re-CCMSH in order to develop a melanoma-targeting peptide that could be labeled with a wider variety of imaging and therapeutic radionuclides.Biodistribution properties of indium-111 ((111)In)--labeled DOTA-Re-CCMSH were compared with the non-DOTA-containing technetium-99m ((99m)Tc)--CCMSH in murine melanoma--bearing C57 mice to determine the effects of DOTA on tumor uptake and whole-body clearance. The tumor targeting capacity and clearance kinetics of (111)In-DOTA-Re-CCMSH were also compared with other related cyclic and linear (111)In-labeled DOTA-alpha-MSH complexes.The in vivo distribution data showed that the conjugation of DOTA to Re-CCMSH did not reduce its initial tumor uptake kinetics but did enhance its tumor retention and renal clearance properties. The tumor uptake of (111)In-DOTA-Re-CCMSH was significantly higher than the other (111)In-DOTA--coupled cyclic or linear alpha-MSH analogs used in this study. Moreover, (111)In-DOTA-Re-CCMSH displayed lower radioactivity accumulation in normal tissues of interest than its non-Re-cyclized counterpart, (111)In-DOTA-CCMSH; the disulfide bond--cyclized (111)In-DOTA-CMSH; or the linear (111)In-DOTA-NDP.Peptide cyclization via rhenium coordination significantly enhanced the tumor targeting and renal clearance properties of DOTA-Re-CCMSH, making it an excellent candidate for melanoma radiodetection and radiotherapy.

    View details for DOI 10.1002/cncr.10284

    View details for Web of Science ID 000173958100002

    View details for PubMedID 11877745

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