Involvement of CPP32/Yama(-like) proteases in Fas-mediated apoptosis

Fas (Apo-1/CD95) belongs to the tumor necrosis factor/nerve growth factor receptor family and transmits apoptotic signals by binding to its ligand. Interleukin-1beta-converting enzyme (ICE), which shows substantial homology to the product of the cell death gene, ced-3, of Caenorhabditis elegans, is reported to be involved in Fas-mediated apoptosis. Using two human carcinoma-derived cell lines with undetectable levels of ICE, we found that an agonistic antihuman Fas antibody induces the activation of CPP32/Yama(-like) proteases that are ICE(-like) protease family members, and that a tetrapeptide inhibitor of CPP32/Yama protease, DEVD-CHO, inhibits the Fas-mediated activation of the proteases, Fas-mediated apoptosis, and CPP32/Yama(-like) proteolytic activities in vitro. Fas-mediated apoptosis is inhibited by the CPP32/Yama inhibitor DEVD-CHO, but not by the ICE inhibitor YVAD-CHO, suggesting a dominant role for the CPP32/Yama(-like) proteases and not ICE itself in Fas-mediated apoptosis of the human carcinoma cell lines.