TGF-BETA-INDUCED APOPTOSIS OF TRANSFORMED FIBROBLASTS BY NORMAL FIBROBLASTS - INDEPENDENCE OF CELL-TO-CELL CONTACT AND DEPENDENCE ON REACTIVE OXYGEN SPECIES

Abstract

We studied the elimination of transformed fibroblasts induced by TGF-beta-treated normal fibroblasts. Kinetic experiments revealed two steps: First, the elimination process is induced in the normal cells by TGF-beta and later, the apoptosis of transformed cells is mediated by a short-lived effector different from TGF-beta and TNF. The killing of the transformed cells is directly observable as a cytopathic effect. It does not depend on cell-to-cell contact between normal and transformed cells. Reactive oxygen species (ROS) play an important role in the elimination process but are not the apoptosis-inducing signal transmitted from TGF-beta-treated normal cells.