PKC-DEPENDENT AND PKC-INDEPENDENT CELLULAR EFFECTS INDUCED BY RECOMBINANT TRANSFORMING GROWTH-FACTOR TYPE-BETA-1

TGF-beta 1 purified from human platelets induces colony formation of r at fibroblasts reversibly when administered together with EGF. TGF-bet a 1 has been reported by us to lead to stable transformation of rat fi broblasts, to activate latent Epstein-Barr virus, to exhibit tumor pro moting activity for murine fibroblasts, and to cause the release of ap optosis-inducing signals from normal cells which are directed specific ally against transformed cells. The use of recombinant TGF-beta 1 in t his study showed that all the effects measured were indeed due to TGF- beta 1. In order to get information on intracellular signal pathways i nduced by TGF-beta 1, specific inhibitors of protein kinase C (PKC) we re applied. Induction of EBV antigens by TGF-beta 1 was dependent on t he function of PKC, whereas induction of apoptosis in transformed cell s by TGF-beta 1-treated normal cells was independent of the action of PKC.