A Potential Role for Immunotherapy in Thyroid Cancer by Enhancing NY-ESO-1 Cancer Antigen Expression

Background: NY-ESO-1 is one of the most immunogenic members of the cancer/testis antigen family and its levels can be increased after exposure to demethylating and deacetylating agents. This cytoplasmic antigen can serve as a potent target for cancer immunotherapy and yet has not been well studied in differentiated thyroid cancer cells. Methods: We studied the baseline expression of NY-ESO-1 messenger RNA and protein before and after exposure to 5-aza-2'-deoxycytidine (DAC) (72 hours) in a panel of thyroid cancer cell lines using quantitative polymerase chain reaction and Western blot. HLA-A2+, NY-ESO-1+ thyroid cell lines were then co-cultured with peripheral blood lymphocytes transduced with NY-ESO-1 specific T-cell receptor (TCR) and assayed for interferon-gamma and Granzyme-B release in the medium. SCID mice injected orthotopically with BCPAP cells were treated with DAC to evaluate for NY-ESO-1 gene expression in vivo. Results: None of the thyroid cancer cell lines showed baseline expression of NY-ESO-1. Three cell lines, BCPAP, TPC-1, and 8505c, showed an increase in NY-ESO-1 gene expression with DAC treatment and were found to be HLA-A2 positive. DAC-treated target BCPAP and TPC-1 tumor cells with up-regulated NY-ESO-1 levels were able to mount an appropriate interferon-gamma and Granzyme-B response upon co-culture with the NY-ESO-1-TCR-transduced peripheral blood lymphocytes. In vivo DAC treatment was able to increase NY-ESO-1 expression in an orthotopic mouse model with BCPAP cells. Conclusion: Our data suggest that many differentiated thyroid cancer cells can be pressed to express immune antigens, which can then be utilized in TCR-based immunotherapeutic interventions.