Expression of the SART1 tumor-rejection antigen in hepatocellular carcinomas

We previously reported a tumor-rejection antigen, SART1259, possessing tumor epitopes capable of inducing cytotoxic T lymphocytes (CTL) in epithelial cancer patients. The present study investigated the expression of the SART1259 antigen in hepatocellular carcinomas (HCC) in order to explore for a potential molecule for use in specific immunotherapy of HCC patients. Expression of the SART1 antigens in samples was analyzed by western blot analysis with anti-SART1259 and anti-SART1800 polyclonal antibodies. In addition HLA-A24- restricted CTLs were induced from peripheral blood mononuclear cells (PBMCs) of HLA-A24+ HCC patients by the SART1690-698 (EYRGFTQDF) peptide with an HLA-A24 binding motif. The SART1259 antigen was detected in the cytoplasmic fraction of 6 of 8 HCC cell lines and 12 of 23 (52%) HCC tissues, but in none of the normal liver tissues or those of chronic hepatitis or cirrhosis. The HLA-A24 restricted and SART1-specific CTLs recognized the HLA-A24+ and SART1259+ HCC cells. Further, in peripheral blood mononuclear cells of HCC patients, the SART1690-698 peptide induced CTLs that reacted to the HCC cells in an HLA-A24-restricted manner. These results suggest that the SART1259 antigen could be an appropriate target molecule for use in specific immunotherapy of HCC patients.