Expression of MAGE genes in colorectal carcinomas

The human genes MAGE-1 and MAGE-3 encode tumor rejection antigens recognized on melanoma cells by cytotoxic T lymphocytes (CTL). These antigens are potentially useful as targets for specific immunotherapy. Expression of MAGE genes in some malignant tumors has been reported, but MAGE gene expression in colorectal carcinomas has not been studied adequately. Therefore, we studied MAGE-1,2,3, and 4 a/4 b expression at the mRNA level, in 40 cases of surgery for colorectal carcinoma, using the reverse transcription polymerase chain reaction (RT-PCR). MAGE-1,2,3, and 4 a/4 b genes were expressed in 3 (7.5%), 6 (15.0%), 13 (32.5%), and 5 (12.5%), respectively, of these 40 cases. A total of 19 of the 40 samples (47.5%) expressed at least one of the MAGE genes. The relationships between clinicopathologic factors and MAGE gene expression were also examined. The frequency of lymph node metastasis was significantly higher in MAGE-3-positive than in MAGE-3-negative cases (p < 0.05). All these cases classified as Duke's D expressed the MAGE-3 gene. This rate of expression was significantly higher than that for all other the Duke's classifications together (p < 0.05). Our findings suggest that MAGE-specific immunotherapy against colorectal carcinomas may be feasible.