Phosphatidylinositol 3-kinase and protein kinase C are required for the inhibition of caspase activity by epidermal growth factor

The mechanism by which growth factors exert an anti-apoptotic function on m any cell types is not well understood. This issue is addressed in relation to epidermal growth factor (EGF) which inhibits apoptosis induced by stauro sporine or wortmannin in an epithelial tumour cell line (CNE-2). The presen ce of EGF substantially reduced the in vitro Ac-DEVD-AMC hydrolytic activit y and almost completely suppressed the intracellular cleavage of poly(ADP-r ibose) polymerase in staurosporine- or wortmannin-treated cells. Staurospor ine but not wortmannin caused the intracellular proteolytic processing of p ro-caspase-3 and this event was transiently inhibited by EGF. Staurosporine -induced apoptosis was not inhibited by EGF in the presence of wortmannin o r LY294002. Similarly, EGF failed to inhibit wortmannin-induced apoptosis i n the presence of staurosporine, chelerythrine chloride or Go6850, These re sults suggest that phosphatidylinositol 3-kinase and protein kinase C play a role in the survival function of EGF but the reduction of cellular caspas e activity cannot be satisfactorily explained by a lack of pro-caspase-3 ac tivation. (C) 1999 Federation of European Biochemical Societies.