Expression of c-erbB-2 in human esophageal carcinoma cells: overexpression correlated with gene amplification or with GATA-3 transcription factor expression.

Amplification and expression of the c-erbB-2 protooncogene was studied in 60 primary human esophageal carcinomas and 12 cell lines established from the carcinomas. Amplification of the c-erbB-2 gene was found in 4 out of 60 (6.7%) and 1 out of 12 (8.3%) DNA samples from the primary carcinomas and cell lines, respectively. Overexpression of c-erbB-2 gene product, as determined by both Northern blot hybridization and immunohistochemical analysis, was found in the cells with c-erbB-2 amplification, but not in normal esophageal mucosae or in primary esophageal carcinomas without gene amplification. In contrast, c-erbB-2 overexpression was clearly observed in 7 cell lines in which gene amplification 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 gene expression. This observation suggested that the GATA-3 transcription factor and c-erbB-2 protein play important roles in the process of immortalization and/or maintenance of the transformed phenotype of human esophageal carcinoma cells in vitro.