ERas oncogene expression and epigenetic regulation by histone acetylation in human cancer cells.

The ERas oncogene is a recently identified gene that supports the tumorigenic growth of embryonic stem (ES) cells by producing a constitutively active Ras protein. However the expression of ERas in cancer cells remains unclear. In this study, ERas mRNA expression was examined in 20 human cancer cell lines and 5 normal cell lines. ERas mRNA was found in 4 out of 7 colorectal carcinomas, 2 out of 6 pancreatic carcinomas, 1 out of 3 breast carcinomas, none in the esophageal carcinomas and none in the normal cells. Histone deacetylase inhibitor treatment resulted in ERas expression in 1 out of 3 colorectal carcinomas, 2 out of 2 breast carcinomas and 3 out of 3 normal cell lines. These findings suggested that the ERas oncogene might be associated with the development of human carcinomas. Up-regulation of ERas by histone acetylation might be one of the mechanisms reversing/overcoming the epigenetic transcriptional silencing of the ERas oncogenes.