MAGE-E1, a new member of the melanoma-associated antigen gene family and its expression in human glioma.

To unearth glioma-specific genes in human glioblastoma, the serial analysis of gene expression technique was applied to a primary glioblastoma, using cultured human astrocytes as a normal control. Among the top 147 most-expressed tags in glioblastoma, we found a tag, TTTTGGGTAT, that originated from an unidentified gene and which was not detected in human astrocyte cultures. Real-time quantitative reverse transcription-PCR showed that MAGE-E1 expression was 2.6-15-fold enriched in glioblastoma relative to human astrocytes. Expressed sequence tags containing this tag were homologous to the melanoma-associated antigen gene (MAGE) family, and this new cDNA, named MAGE-E1, was cloned by the 5'-rapid amplification of cDNA ends technique. Three alternatively spliced variants (MAGE-E1a-c) were found, and deduced amino acid sequence showed that MAGE-E1a and -E1b shared the MAGE-conserved region, whereas -E1c did not. This suggests that although MAGE-E1c is expressed from one of the MAGE family, it has distinct functions from other members. Tissue distribution analysis showed that MAGE-E1 was distinct from other MAGEs. MAGE-E1 expression was detected only in brain and ovary among normal tissues. Interestingly, MAGE-E1a and/or -E1b were specifically expressed in glioma cells among cancer cells. These results indicate that MAGE-E1 is a novel and glioma-specific member of MAGE family.