Vanadate, epidermal growth factor and prostaglandin E2 production in human amnion cells

We have investigated the effects of vanadate (VAN) and mouse epidermal growth factor (mEGF) on prostaglandin (PG) E2 production in human amnion cells in monolayer culture that served as a model system. The secretion of PGE2 into the culture medium was quantified by radioimmunoassay. The rate of conversion of [14C] arachidonic acid to [14C] PGE2 (PGE2 synthase) was determined in cell sonicates under optimal in vitro conditions. After a treatment period of 4 h we observed an increase in PGE2 production in the presence of mEGF (4.7-fold), VAN (1.8-fold) or both agents (6.8-fold) over control samples. Similarly, the specific activity of PGE2 synthase was stimulated maximally after 4 h with mEGF (2.1-fold), VAN (1.7-fold) or with both (4.8-fold) compared with untreated tissue samples. In the presence of cycloheximide those effects were abolished. We suggest, that VAN and mEGF act by a mechanism(s) that involves de novo protein synthesis or that alters the phosphorylation state of enzymes that are requisite for the conversion of arachidonic acid to PGE2.