Characterization of the GAGE genes that are expressed in various human cancers and in normal testis

The GAGE-1 gene was identified previously as a gene that codes for an antig enic peptide, YRPRPRRY, which was presented on a human melanoma by HLA-Cw6 molecules and recognized by a clone of CTLs derived from the patient bearin g the tumor. By screening a cDNA library from this melanoma, we identified five additional, closely related genes named GAGE-2-6, We report here that further screening of this library led to the identification of two more gen es, GAGE-7B and -8 GAGE-1, -2, and -8 code for peptide YRPRPRRY. Using anot her antitumor CTL clone isolated from the same melanoma patient, se identif ied antigenic peptide, YYWPRPRRY, which is encoded by GAGE-3, -4, -5, -6, a nd -7B and which is presented by HLA-A29 molecules. Genomic cloning of GAGE -7B showed that it is composed of five exons. Sequence alignment showed tha t an additional exon, which is present only in the mRNA of GAGE-1, has been disrupted in gene GAGE-7B by the insertion of a long interspersed repeated element retroposon. These GAGE genes are located in the p11.2 - p11.4 regi on of chromosome X, They are not expressed in normal tissues, except in tes tis, but a large proportion of tumors of various histological origins expre ss at least one of these genes. Treatment of normal and tumor cultured cell s with a demethylating agent, azadeoxycytidine, resulted in the transcripti onal activation of GAGE genes, suggesting that their expression in tumors r esults from a demethylation process.