EXPRESSION OF C-ERBB-2 IN HUMAN ESOPHAGEAL-CARCINOMA CELLS - OVEREXPRESSION CORRELATED WITH GENE AMPLIFICATION OR WITH GATA-3 TRANSCRIPTIONFACTOR EXPRESSION

Amplification and expression of the c-erbB-2 protooncogene was studied in 60 primary human esophageal carcinomas and 12 cell lines establish ed from the carcinomas. Amplification of the c-erbB-2 gene was found i n 4 out of 60 (6.7%) and 1 out of 12 (8.3%) DNA samples from the prima ry carcinomas and cell lines, respectively. Overexpression of c-erbB-2 gene product, as determined by both Northern blot hybridization and i mmunohistochemical analysis, was found in the cells with c-erbB-2 ampl ification, but not in normal esophageal mucosae or in primary esophage al carcinomas without gene amplification. In contrast, c-erbB-2 overex pression was clearly observed in 7 cell lines in which gene amplificat ion was not found. We analyzed expression of the GATA-3 transcription factor in the carcinoma cell lines and found that the level of GATA-3 mRNA expression showed very good correlation with that of c-erbB-2 gen e expression. This observation suggested that the GATA-3 transcription factor and c-erbB-2 protein play important roles in the process of im mortalization and/or maintenance of the transformed phenotype of human esophageal carcinoma cells in vitro.