Background: The authors recently reported that the SART2 and SART3 antigens encode tumor epitopes recognized by HLA-A24-restricted and tumor-specific cytotoxic T lymphocytes (CTLs) established from esophageal carcinoma patients. The current study investigated these antigens to explore a potential molecule for specific immunotherapy for colorectal carcinoma patients.
Methods: The SART2 and SART3 antigens were investigated by Western blotting in colorectal carcinoma cell lines and in cancer tissues. For induction of CTLs, peripheral blood mononuclear cells (PBMCs) of HLA A-24-positive cancer patients were stimulated in vitro with peptides.
Results: The 140 kD SART3 antigen was expressed in both the cytosol and nuclear fractions of all six colon carcinoma cell lines, 27 of 41 (65.9%) cytosol fractions, 30 of 41 (73.2%) nuclear fractions of colorectal carcinoma tissue samples, and in 0 of 7 non-tumorous tissues. The 100 kD SART2 antigen was expressed in the cytosol fractions of 2 of 6 colon carcinoma cell lines, 5 of 20 (25%) cytosol fractions of colorectal carcinoma tissue samples, and in 0 of 7 non tumorous tissues. HLA-A24-restricted CTLs cytotoxic to colon carcinoma cells were induced from PBMCs of colon carcinoma patients by stimulation with the two immunogenic peptides of SART3.
Conclusions: The SART3 antigen could be an appropriate target molecule for specific immunotherapy for colorectal carcinoma patients.
Copyright 2002 American Cancer Society.