EXPRESSION OF C-FOS IN CULTURED HUMAN NEVUS CELLS - AN INCREASE OVER MELANOCYTES AND MELANOMA-CELLS

Nevus cells exhibit growth characteristics in culture which differenti ate them from melanocytes and melanoma cells. We examined the expressi on of c-jun, c-fos and jun-B mRNA levels in cultures of different mela nocytic cell types to determine if biologic differences among these ce lls was due to their level of proto-oncogene expression. Because cell growth and differentiation are also known to be affected by serum cond itions, the expression of c-jun, c-fos and jun-B was examined under no rmal serum conditions and serum starved and repleted conditions which stimulates proto-oncogene expression. Expression of c-jun and jun-B wa s not significantly different among the cell types studied under norma l serum conditions, or serum starved and refed conditions and c-fos wa s not detectable in any of the unstimulated cell types. In contrast, w hen the cells were serum starved and refed, the level of c-fos express ion was uniformly increased (2-10 fold) in 3 different nevus cell line s. This increase was not seen in normal melanocyte cultures or 2 melan oma cell lines. With serum deprivation and repletion, c-fos was also e levated in I melanoma cell line. We conclude that the regulation of th e proto-oncogene c-fos is different in nevus cells than in normal mela nocytes, which may contribute to the different growth characteristics seen with nevus cells.