Although cytotoxic T lymphocyte (CTL)-directed
epitopes binding to human histocompatibility leukocyte
antigen (
HLA)-A molecules have been well characterized, those binding to
HLA-B molecules have not, largely due to their large diversity. In this study we report a unique
cancer antigen gene, tentatively named Testin-related gene (TRG), which encodes CTL-directed
epitopes on the
HLA-B52 molecules most frequently expressed in Asians. TRG is located in an intron of the putative tumor suppressor gene Testin in the common fragile site 7G region at 7q31.2. TRG
mRNA was expressed in the majority of
cancer cells and
cancer tissue tested, whereas it was scarcely expressed in the majority of normal tissues, and only low-level expression of TRG was detected in the heart, liver, and pancreas. One TRG
peptide had the ability to induce HLA-B52-restricted CTL cytotoxic to TRG+
tumor cells in peripheral blood mononuclear cells (PBMC) of epithelial
cancer patients. This
peptide also induced HLA-B62-restricted and
tumor-reactive CTL in PBMC of
cancer patients. Therefore, this TRG-derived
peptide might be appropriate for use in
peptide-based
immunotherapy for relatively large numbers of
cancer patients throughout the world, given that 34% of Japanese, 27% of Chinese, and 13% of Caucasians express either
HLA-B52 or HLA-B62 molecules