Induction of c-fos and AFP expression in a differentiating teratocarcinoma cell line.

The introduction of a c-fos expression vector has been shown to potentiate spontaneous differentiation in teratocarcinoma cells. We have studied a teratocarcinoma stem cell line which can be induced to differentiate with dimethylsulfoxide (DMSO) to determine endogenous c-fos expression during the process of differentiation. c-Fos expression increases dramatically as P19S1801A1 embryonal carcinoma cells are induced to differentiate into a variety of cell types. Expression peaks 12 days after the start of aggregate culture about the same time as alphafetoprotein (AFP), a characteristic of visceral endoderm differentiation, as demonstrated by RNA hybridization to specific probes, ELISA, and immunofluorescent staining with specific antibodies. However, most differentiated cells expressed c-fos, while AFP was expressed in a minor fraction (less than 5%). The data suggest that c-fos is correlated with differentiation of teratocarcinoma cells but not specifically to visceral endoderm formation.