Nathan Reticker-Flynn

All Publications

• Systemic Immunity Is Required for Effective Cancer Immunotherapy. Cell Spitzer, M. H., Carmi, Y., Reticker-Flynn, N. E., Kwek, S. S., Madhireddy, D., Martins, M. M., Gherardini, P. F., Prestwood, T. R., Chabon, J., Bendall, S. C., Fong, L., Nolan, G. P., Engleman, E. G. 2017; 168 (3): 487-502 e15

  Abstract

  Immune responses involve coordination across cell types and tissues. However, studies in cancer immunotherapy have focused heavily on local immune responses in the tumor microenvironment. To investigate immune activity more broadly, we performed an organism-wide study in genetically engineered cancer models using mass cytometry. We analyzed immune responses in several tissues after immunotherapy by developing intuitive models for visualizing single-cell data with statistical inference. Immune activation was evident in the tumor and systemically shortly after effective therapy was administered. However, during tumor rejection, only peripheral immune cells sustained their proliferation. This systemic response was coordinated across tissues and required for tumor eradication in several immunotherapy models. An emergent population of peripheral CD4 T cells conferred protection against new tumors and was significantly expanded in patients responding to immunotherapy. These studies demonstrate the critical impact of systemic immune responses that drive tumor rejection.

  View details for DOI 10.1016/j.cell.2016.12.022

  View details for PubMedID 28111070

  View details for PubMedCentralID PMC5312823

• Aberrant Glycosylation Promotes Lung Cancer Metastasis through Adhesion to Galectins in the Metastatic Niche CANCER DISCOVERY Reticker-Flynn, N. E., Bhatia, S. N. 2015; 5 (2): 168-181

  Abstract

  Metastasis is the leading cause of cancer-associated deaths. Although dissemination of tumor cells likely occurs early in tumorigenesis, the constituents of the microenvironment play essential rate-limiting roles in determining whether these cells will form clinically relevant tumors. Recent studies have uncovered many molecular factors that contribute to the establishment of a protumorigenic metastatic niche. Here, we demonstrate that galectin-3, whose expression has clinical associations with advanced malignancy and poor outcome, contributes to metastatic niche formation by binding to carbohydrates on metastatic cells. We show that galectin-3 is expressed early during tumorigenesis by both CD11b(+)Gr-1(+) and CD11b(+)Ly-6C(hi) leukocytes. Tumors mobilize these myeloid populations through secretion of soluble factors, including IL6. We find that metastatic cancer cells exhibit elevated presentation of the oncofetal galectin-3 carbohydrate ligand, the Thomsen-Friedenreich antigen, on their surfaces as a result of altered C2GnT2 and St6GalNAc4 glycosyltransferase activity that inhibits further glycosylation of this carbohydrate motif and promotes metastasis.Although clinical observations of elevated serum galectin-3 levels and altered glycosylation have been associated with malignancy, we identify novel roles for glycosyltransferases in promoting adhesion to galectins in the metastatic niche. This identification of a cytokine-leukocyte-glycosylation axis in metastasis provides mechanistic explanations for clinical associations between malignancy and aberrant glycosylation.

  View details for DOI 10.1158/2159-8290.CD-13-0760

  View details for Web of Science ID 000349393600025

  View details for PubMedID 25421439

• A combinatorial extracellular matrix platform identifies cell-extracellular matrix interactions that correlate with metastasis NATURE COMMUNICATIONS Reticker-Flynn, N. E., Malta, D. F., Winslow, M. M., Lamar, J. M., Xu, M. J., Underhill, G. H., Hynes, R. O., Jacks, T. E., Bhatia, S. N. 2012; 3

  Abstract

  Extracellular matrix interactions have essential roles in normal physiology and many pathological processes. Although the importance of extracellular matrix interactions in metastasis is well documented, systematic approaches to identify their roles in distinct stages of tumorigenesis have not been described. Here we report a novel-screening platform capable of measuring phenotypic responses to combinations of extracellular matrix molecules. Using a genetic mouse model of lung adenocarcinoma, we measure the extracellular matrix-dependent adhesion of tumour-derived cells. Hierarchical clustering of the adhesion profiles differentiates metastatic cell lines from primary tumour lines. Furthermore, we uncovered that metastatic cells selectively associate with fibronectin when in combination with galectin-3, galectin-8 or laminin. We show that these molecules correlate with human disease and that their interactions are mediated in part by α3β1 integrin. Thus, our platform allowed us to interrogate interactions between metastatic cells and their microenvironments, and identified extracellular matrix and integrin interactions that could serve as therapeutic targets.

  View details for DOI 10.1038/ncomms2128

  View details for Web of Science ID 000313514100032

  View details for PubMedID 23047680

• A gut punch fights cancer and infection NATURE Reticker-Flynn, N. E., Engleman, E. G. 2019; 565 (7741): 573–74

  View details for Web of Science ID 000457404000031

  View details for PubMedID 30683936

• An Immunosuppressive Dendritic Cell Subset Accumulates at Secondary Sites and Promotes Metastasis in Pancreatic Cancer. Cancer research Kenkel, J. A., Tseng, W. W., Davidson, M. G., Tolentino, L. L., Choi, O., Bhattacharya, N., Seeley, E. S., Winer, D. A., Reticker-Flynn, N. E., Engleman, E. G. 2017; 77 (15): 4158–70

  Abstract

  Pancreatic ductal adenocarcinoma (PDAC) after complete surgical resection is often followed by distant metastatic relapse for reasons that remain unclear. In this study, we investigated how the immune response at secondary sites affects tumor spread in murine models of metastatic PDAC. Early metastases were associated with dense networks of CD11b+CD11c+MHC-II+CD24+CD64lowF4/80lowdendritic cells (DC), which developed from monocytes in response to tumor-released GM-CSF. These cells uniquely expressed MGL2 and PD-L2 in the metastatic microenvironment and preferentially induced the expansion of T regulatory cells (Treg)in vitroandin vivoTargeted depletion of this DC population inMgl2DTRhosts activated cytotoxic lymphocytes, reduced Tregs, and inhibited metastasis development. Moreover, blocking PD-L2 selectively activated CD8 T cells at secondary sites and suppressed metastasis, suggesting that the DCs use this particular pathway to inhibit CD8 T-cell-mediated tumor immunity. Phenotypically similar DCs accumulated at primary and secondary sites in other models and in human PDAC. These studies suggest that a discrete DC subset both expands Tregs and suppresses CD8 T cells to establish an immunosuppressive microenvironment conducive to metastasis formation. Therapeutic strategies to block the accumulation and immunosuppressive activity of such cells may help prevent PDAC progression and metastatic relapse after surgical resection.Cancer Res; 77(15); 4158-70. ©2017 AACR.

  View details for PubMedID 28611041

• Akt and SHP-1 are DC-intrinsic checkpoints for tumor immunity. JCI insight Carmi, Y., Prestwood, T. R., Spitzer, M. H., Linde, I. L., Chabon, J., Reticker-Flynn, N. E., Bhattacharya, N., Zhang, H., Zhang, X., Basto, P. A., Burt, B. M., Alonso, M. N., Engleman, E. G. 2016; 1 (18)

  Abstract

  BM-derived DC (BMDC) are powerful antigen-presenting cells. When loaded with immune complexes (IC), consisting of tumor antigens bound to antitumor antibody, BMDC induce powerful antitumor immunity in mice. However, attempts to employ this strategy clinically with either tumor-associated DC (TADC) or monocyte-derived DC (MoDC) have been disappointing. To investigate the basis for this phenomenon, we compared the response of BMDC, TADC, and MoDC to tumor IgG-IC. Our findings revealed, in both mice and humans, that upon exposure to IgG-IC, BMDC internalized the IC, increased costimulatory molecule expression, and stimulated autologous T cells. In contrast, TADC and, surprisingly, MoDC remained inert upon contact with IC due to dysfunctional signaling following engagement of Fcγ receptors. Such dysfunction is associated with elevated levels of the Src homology region 2 domain-containing phosphatase-1 (SHP-1) and phosphatases regulating Akt activation. Indeed, concomitant inhibition of both SHP-1 and phosphatases that regulate Akt activation conferred upon TADC and MoDC the capacity to take up and process IC and induce antitumor immunity in vivo. This work identifies the molecular checkpoints that govern activation of MoDC and TADC and their capacity to elicit T cell immunity.

  View details for PubMedID 27812544

  View details for PubMedCentralID PMC5085602

• Normalizing Microbiota-Induced Retinoic Acid Deficiency Stimulates Protective CD8(+) T Cell-Mediated Immunity in Colorectal Cancer. Immunity Bhattacharya, N., Yuan, R., Prestwood, T. R., Penny, H. L., DiMaio, M. A., Reticker-Flynn, N. E., Krois, C. R., Kenkel, J. A., Pham, T. D., Carmi, Y., Tolentino, L., Choi, O., Hulett, R., Wang, J., Winer, D. A., Napoli, J. L., Engleman, E. G. 2016; 45 (3): 641-655

  Abstract

  Although all-trans-retinoic acid (atRA) is a key regulator of intestinal immunity, its role in colorectal cancer (CRC) is unknown. We found that mice with colitis-associated CRC had a marked deficiency in colonic atRA due to alterations in atRA metabolism mediated by microbiota-induced intestinal inflammation. Human ulcerative colitis (UC), UC-associated CRC, and sporadic CRC specimens have similar alterations in atRA metabolic enzymes, consistent with reduced colonic atRA. Inhibition of atRA signaling promoted tumorigenesis, whereas atRA supplementation reduced tumor burden. The benefit of atRA treatment was mediated by cytotoxic CD8(+) T cells, which were activated due to MHCI upregulation on tumor cells. Consistent with these findings, increased colonic expression of the atRA-catabolizing enzyme, CYP26A1, correlated with reduced frequencies of tumoral cytotoxic CD8(+) T cells and with worse disease prognosis in human CRC. These results reveal a mechanism by which microbiota drive colon carcinogenesis and highlight atRA metabolism as a therapeutic target for CRC.

  View details for DOI 10.1016/j.immuni.2016.08.008

  View details for PubMedID 27590114

  View details for PubMedCentralID PMC5132405

• Extracellular matrix microarrays to study inductive signaling for endoderm specification. Acta biomaterialia Malta, D. F., Reticker-Flynn, N. E., da Silva, C. L., Cabral, J. M., Fleming, H. E., Zaret, K. S., Bhatia, S. N., Underhill, G. H. 2016; 34: 30-40

  Abstract

  During tissue development, stem and progenitor cells are faced with fate decisions coordinated by microenvironmental cues. Although insights have been gained from in vitro and in vivo studies, the role of the microenvironment remains poorly understood due to the inability to systematically explore combinations of stimuli at a large scale. To overcome such restrictions, we implemented an extracellular matrix (ECM) array platform that facilitates the study of 741 distinct combinations of 38 different ECM components in a systematic, unbiased and high-throughput manner. Using embryonic stem cells as a model system, we derived definitive endoderm progenitors and applied them to the array platform to study the influence of ECM, including the interactions of ECM with growth factor signaling, on the specification of definitive endoderm cells towards the liver and pancreas fates. We identified ECM combinations that influence endoderm fate decisions towards these lineages, and demonstrated the utility of this platform for studying ECM-mediated modifications to signal activation during liver specification. In particular, defined combinations of fibronectin and laminin isoforms, as well as combinations of distinct collagen subtypes, were shown to influence SMAD pathway activation and the degree of hepatic differentiation. Overall, our systematic high-throughput approach suggests that ECM components of the microenvironment have modulatory effects on endoderm differentiation, including effects on lineage fate choice and cell adhesion and survival during the differentiation process. This platform represents a robust tool for analyzing effects of ECM composition towards the continued improvement of stem cell differentiation protocols and further elucidation of tissue development processes.Cellular microarrays can provide the capability to perform high-throughput investigations into the role of microenvironmental signals in a variety of cell functions. This study demonstrates the utility of a high-throughput cellular microarray approach for analyzing the effects of extracellular matrix (ECM) in liver and pancreas differentiation of endoderm progenitor cells. Despite an appreciation that ECM is likely involved in these processes, the influence of ECM, particularly combinations of matrix proteins, had not been systematically explored. In addition to the identification of relevant ECM compositions, this study illustrates the capability of the cellular microarray platform to be integrated with a diverse range of cell fate measurements, which could be broadly applied towards the investigation of cell fate regulation in other tissue development and disease contexts.

  View details for DOI 10.1016/j.actbio.2016.02.014

  View details for PubMedID 26883775