![]() The MAGE-A and -B genes code for antigens that are recognized by autologous T cells. We report here that one MAGE homologue recorded in databanks is expressed ubiquitously. In an attempt to identify new MAGE genes that may encode tumor-specific antigens, we performed a search of protein databanks for MAGE-related protein sequences. The activation of these genes appears to result from the demethylation of their promoter region (8). Seven MAGE-A genes, two MAGE-B genes, and two MAGE-C genes are expressed in a significant proportion of tumors of various histological types. These MAGE-A, -B and -C genes are not expressed in normal tissues, except in male germ-line cells, and, for some of these genes, in placenta. 3 They were identified following the analysis of cDNA libraries enriched for tumor- and testis-specific sequences by representational difference analysis. MAGE-C, a third group, comprises two genes located in Xq26-27 (7). A sequencing effort directed at the Xp21 region led to the identification of the MAGE-B cluster, which comprises four genes (4, 5, 6). Together, these 12 genes form the MAGE-A cluster, located in the q28 region of the X chromosome (3). By hybridization of cosmids with a MAGE-A1 probe, 11 closely related genes were identified (2). The human gene MAGE-A1 was identified by a gene transfection approach involving the stimulation of CTLs directed against a melanoma cell line (1). ![]()
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