Ece Canan Sayitoglu

All Publications

• Boosting Natural Killer Cell-Mediated Targeting of Sarcoma Through DNAM-1 and NKG2D. Frontiers in immunology Sayitoglu, E. C., Georgoudaki, A. M., Chrobok, M., Ozkazanc, D., Josey, B. J., Arif, M., Kusser, K., Hartman, M., Chinn, T. M., Potens, R., Pamukcu, C., Krueger, R., Zhang, C., Mardinoglu, A., Alici, E., Temple, H. T., Sutlu, T., Duru, A. D. 2020; 11: 40

  Abstract

  Sarcomas are malignancies of mesenchymal origin that occur in bone and soft tissues. Many are chemo- and radiotherapy resistant, thus conventional treatments fail to increase overall survival. Natural Killer (NK) cells exert anti-tumor activity upon detection of a complex array of tumor ligands, but this has not been thoroughly explored in the context of sarcoma immunotherapy. In this study, we investigated the NK cell receptor/ligand immune profile of primary human sarcoma explants. Analysis of tumors from 32 sarcoma patients identified the proliferative marker PCNA and DNAM-1 ligands CD112 and/or CD155 as commonly expressed antigens that could be efficiently targeted by genetically modified (GM) NK cells. Despite the strong expression of CD112 and CD155 on sarcoma cells, characterization of freshly dissociated sarcomas revealed a general decrease in tumor-infiltrating NK cells compared to the periphery, suggesting a defect in the endogenous NK cell response. We also applied a functional screening approach to identify relevant NK cell receptor/ligand interactions that induce efficient anti-tumor responses using a panel NK-92 cell lines GM to over-express 12 different activating receptors. Using GM NK-92 cells against primary sarcoma explants (n = 12) revealed that DNAM-1 over-expression on NK-92 cells led to efficient degranulation against all tested explants (n = 12). Additionally, NKG2D over-expression showed enhanced responses against 10 out of 12 explants. These results show that DNAM-1+ or NKG2D+ GM NK-92 cells may be an efficient approach in targeting sarcomas. The degranulation capacity of GM NK-92 cell lines was also tested against various established tumor cell lines, including neuroblastoma, Schwannoma, melanoma, myeloma, leukemia, prostate, pancreatic, colon, and lung cancer. Enhanced degranulation of DNAM-1+ or NKG2D+ GM NK-92 cells was observed against the majority of tumor cell lines tested. In conclusion, DNAM-1 or NKG2D over-expression elicited a dynamic increase in NK cell degranulation against all sarcoma explants and cancer cell lines tested, including those that failed to induce a notable response in WT NK-92 cells. These results support the broad therapeutic potential of DNAM-1+ or NKG2D+ GM NK-92 cells and GM human NK cells for the treatment of sarcomas and other malignancies.

  View details for DOI 10.3389/fimmu.2020.00040

  View details for PubMedID 32082316

  View details for PubMedCentralID PMC7001093

• Engineering antigen-specific NK cell lines against the melanoma-associated antigen tyrosinase via TCR gene transfer EUROPEAN JOURNAL OF IMMUNOLOGY Parlar, A., Sayitoglu, E., Ozkazanc, D., Georgoudaki, A., Pamukcu, C., Aras, M., Josey, B. J., Chrobok, M., Branecki, S., Zahedimaram, P., Ikromzoda, L., Alici, E., Erman, B., Duru, A. D., Sutlu, T. 2019; 49 (8): 1278–90

  Abstract

  Introduction of Chimeric Antigen Receptors to NK cells has so far been the main practical method for targeting NK cells to specific surface antigens. In contrast, T cell receptor (TCR) gene delivery can supply large populations of cytotoxic T-lymphocytes (CTL) targeted against intracellular antigens. However, a major barrier in the development of safe CTL-TCR therapies exists, wherein the mispairing of endogenous and genetically transferred TCR subunits leads to formation of TCRs with off-target specificity. To overcome this and enable specific intracellular antigen targeting, we have tested the use of NK cells for TCR gene transfer to human cells. Our results show that ectopic expression of TCR α/β chains, along with CD3 subunits, enables the functional expression of an antigen-specific TCR complex on NK cell lines NK-92 and YTS, demonstrated by using a TCR against the HLA-A2-restricted tyrosinase-derived melanoma epitope, Tyr368-377 . Most importantly, the introduction of a TCR complex to NK cell lines enables MHC-restricted, antigen-specific killing of tumor cells both in vitro and in vivo. Targeting of NK cells via TCR gene delivery stands out as a novel tool in the field of adoptive immunotherapy which can also overcome the major hurdle of "mispairing" in TCR gene therapy.

  View details for DOI 10.1002/eji.201948140

  View details for Web of Science ID 000478643000013

  View details for PubMedID 31054264

• Successive crystal structure snapshots suggest the basis for MHC class I peptide loading and editing by tapasin PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Hafstrand, I., Sayitoglu, E., Apavaloaei, A., Josey, B., Sun, R., Han, X., Pellegrino, S., Ozkazanc, D., Potens, R., Janssen, L., Nilvebrant, J., Nygren, P., Sandalova, T., Springer, S., Georgoudaki, A., Duru, A., Achour, A. 2019; 116 (11): 5055–60

  Abstract

  MHC-I epitope presentation to CD8+ T cells is directly dependent on peptide loading and selection during antigen processing. However, the exact molecular bases underlying peptide selection and binding by MHC-I remain largely unknown. Within the peptide-loading complex, the peptide editor tapasin is key to the selection of MHC-I-bound peptides. Here, we have determined an ensemble of crystal structures of MHC-I in complex with the peptide exchange-associated dipeptide GL, as well as the tapasin-associated scoop loop, alone or in combination with candidate epitopes. These results combined with mutation analyses allow us to propose a molecular model underlying MHC-I peptide selection by tapasin. The N termini of bound peptides most probably bind first in the N-terminal and middle region of the MHC-I peptide binding cleft, upon which the peptide C termini are tested for their capacity to dislodge the tapasin scoop loop from the F pocket of the MHC-I cleft. Our results also indicate important differences in peptide selection between different MHC-I alleles.

  View details for DOI 10.1073/pnas.1807656116

  View details for Web of Science ID 000460911500051

  View details for PubMedID 30808808

  View details for PubMedCentralID PMC6421438

• Functional Assessment for Clinical Use of Serum-Free Adapted NK-92 Cells CANCERS Chrobok, M., Dahlberg, C. M., Sayitoglu, E., Beljanski, V., Nahi, H., Gilljam, M., Stellan, B., Sutlu, T., Duru, A., Alici, E. 2019; 11 (1)

  Abstract

  Natural killer (NK) cells stand out as promising candidates for cellular immunotherapy due to their capacity to kill malignant cells. However, the therapeutic use of NK cells is often dependent on cell expansion and activation with considerable amounts of serum and exogenous cytokines. We aimed to develop an expansion protocol for NK-92 cells in an effort to generate a cost-efficient, xeno-free, clinical grade manufactured master cell line for therapeutic applications. By making functional assays with NK-92 cells cultured under serum-free conditions (NK-92SF) and comparing to serum-supplemented NK-92 cells (NK-92S) we did not observe significant alterations in the viability, proliferation, receptor expression levels, or in perforin and granzyme levels. Interestingly, even though NK-92SF cells displayed decreased degranulation and cytotoxicity against tumor cells in vitro, the degranulation capacity was recovered after overnight incubation with 20% serum in the medium. Moreover, lentiviral vector-based genetic modification efficiency of NK-92SF cells was comparable with NK-92S cells. The application of similar strategies can be useful in reducing the costs of manufacturing cells for clinical use and can help us understand and implement strategies towards chemically defined expansion and genetic modification protocols.

  View details for DOI 10.3390/cancers11010069

  View details for Web of Science ID 000457233300033

  View details for PubMedID 30634595

  View details for PubMedCentralID PMC6356567