Growth inhibitory effect of green tea extract in Ehrlich ascites tumor cells involves cytochrome c release and caspase activation

We reported previously that the mechanism by which Green tea extract (GTE) elicited growth-inhibitory effects in Ehrlich ascites tumor cells involved a decrease in ornithine decarboxylase (ODC) activity and in cell viability. Decrease in ODC activity has been associated with apoptotic cell death and we therefore studied changes in cytochrome c release and caspase activatio n, which characterize apoptosis. GTE caused a dose- and rime-dependent incr ease in caspase-3-like protease activation, preceded by a release of cytoch rome c from the mitochondria. Inhibiting the activation of caspase-3 with a cetyl-Asp-Glu-Val-Asp-alpha -aldehyde (caspase inhibitor) caused a reversal in the effect on cell viability. (C) 2001 Elsevier Science Ireland Ltd. Al l rights reserved.