Bcl-2 prevents TNF- and Fas-induced cell death but does not inhibit initial processing of caspase-3

The members of ICE/CED3 family of cysteine proteases (caspases) play important roles in the regulation of programmed cell death. Recent studies have revealed that processing and activation of CPP32 (CASP-3) are crucial for executing cell death in TNF-α- and Fas-induced apoptosis. Overexpression of Bcl-2 in HeLa cells inhibits the cell death and CASP-3 like protease activities which are induced by TNF-α or anti-Fas antibody. Preform of CASP-3 disappered after the treatment with TNF-α or anti-Fas antibody in both HeLa cells and HeLa/bcl-2 cells. These results suggest Bcl-2 prevents cell death and activation of CASP-3 but does not inhibit initial processing of CASP-3.