Growth advantage by overexpression of normal Harvey ras proto-oncogene in cultured rat epidermal keratinocytes.

The ras proto-oncogene is frequently amplified and overexpressed in the hyperproliferative conditions of epidermal keratinocytes. To investigate the effects of its overexpression on the growth of keratinocytes in a model system, we constructed expression vectors for normal human Ha-ras and introduced them into FRSK cells, a fetal rat epidermal keratinocyte cell line. Several clones containing the transfected Ha-ras were isolated, and two of them overexpressed this gene. In these clones DNA synthesis and cell growth were greater than in other clones expressing this gene at low levels. Thus we suggest that overexpression of normal ras gene may provide growth advantage to epidermal keratinocytes.