Expression of MAGE-1, MAGE-2 and MAGE-3 genes in human gastric carcinomas; lack of evidence for cytotoxic effects in cases with simultaneous expression of MAGE-3 and HLA-A2.

The human MAGE gene products are recognized by major histocompatibility complex-restricted cytotoxic T lymphocytes. We analyzed by RT-PCR the expression of MAGE-1, MAGE-2, MAGE-3 and HLA-A2 genes in 10 human gastric cancer cell lines and 46 human stomachs removed due to advanced gastric carcinomas. All the cell lines expressed MAGE genes, except for MKN-45 and -74 which lacked the expression of MAGE-1 and -3 genes in this study. Of the 46 gastric carcinomas, MAGE-1, -2 and -3 genes were expressed in 14 (30%), 10 (22%) and 26 (57%) cases, respectively, regardless of histological type. Normal gastric mucosa and intestinal metaplastic mucosa showed no expression of these genes. HLA-A2 gene expression was noted in 14 both normal and carcinoma cases. Simultaneous expression of MAGE-3 and HLA-A2 genes was noted in 7 cases. Mean apoptotic and Ki-67-labeling indices (AI and KI) of carcinoma cells were 2.3 +/- 0.5 and 48.1 +/- 6.0 in 7 cases, and 2.8 +/- 0.2 and 47.3 +/- 2.7 in the other 39 cases lacking the expression of MAGE-3 and/or HLA-A2 genes, respectively. The two-year survival rate did not differ between the two groups. Although this study confirmed the relatively higher expression of the MAGE gene family in human advanced gastric carcinomas, it might suggest that simultaneous expression of MAGE-3 and HLA-A2 genes does not necessarily imply the induction of cancer cell apoptosis by CTL.