ROLE OF PROLIFERATION FOR INTERCELLULAR INDUCTION OF APOPTOSIS

We have recently described induction of apoptosis of transformed targe t cells by TGF-beta-treated nontransformed effector cells as a potenti al novel control step in oncogenesis. Here we study the role of prolif eration of both cell types for the efficiency of induction of apoptosi s. Inhibition of proliferation of transformed target cells by gamma ir radiation or colchicine treatment did not affect their sensitivity to induction of apoptosis by TGF-beta-treated nontransformed effector cel ls. This finding indicates that sensitivity to intercellular induction of apoptosis is not related to cell cycle control. In contrast, the a bility of nontransformed effector cells to induce apoptosis was depend ent on their proliferation, Nontransformed cells blocked by gamma irra diation, colchicine treatment, or thymidine treatment were no longer a ble to induce apoptosis of transformed target cells, This inability se ems to be partially due to substances that are released from prolifera tion-inhibited nontransformed effector cells and that interfere with i nduction of apoptosis. (C) 1997 Academic Press.