TGF-beta and FGF-trigger intercellular induction of apoptosis: analogous activity on non-transformed but differential activity on transformed cells.

Transforming growth factor (TGF)-beta as well as fibroblast growth factor (FGF) are able to trigger intercellular induction of apoptosis. Interaction of either cytokine with non-transformed cells results in the production and release of apoptosis inducing factor (AIF) which is specifically directed against transformed cells. In both cases, AIF production is inhibited by the antioxidant N-Acetylcysteine, indicating that similar or identical signalling pathways are utilized. Whereas TGF-beta sensitizes transformed cells by down modulation of their endogenous survival factors, FGF is devoid of a similar activity. Therefore TGF-beta triggers and enhances intercellular induction of apoptosis by interaction with non-transformed and transformed cells, whereas the activity of FGF is based only on the interaction with non-transformed cells.