KILLER/DR5, a novel DNA-damage inducible death receptor gene, links the p53-tumor suppressor to caspase activation and apoptotic death.

TRAIL and its emerging receptors are the newest members of the TNF receptor super-family. The activation of TRAIL receptors by ligand binding leads to apoptosis through caspase activation through an as yet unclear signaling pathway that does not require the FADD adaptor. The TRAIL receptor KILLER/DR5, is induced by DNA damage and appears to be regulated by the tumor suppressor gene p53. Both the Fas receptor and KILLER/DR5 provide potential links between DNA damage-mediated activation of the p53 tumor suppressor and caspase activation. While further evaluation of the role of TRAIL receptors in human cancer is ongoing, initial studies suggest that both KILLER/DR5 and DR4 may be targets for inactivation and that these pro-apooptotic receptors may be tumor suppressor genes. Understanding the regulation of TRAIL and its receptors may thus be beneficial for the development of novel approaches for cancer treatment. TRAIL appears to be a cancer-specific cytotoxic agent and thus offers promise as a novel therapy for cancer either through replacement of the cytokine or potentially via gene replacement. Preliminary studies suggest the potential to combine TRAIL with classical cytotoxic chemotherapeutic drugs to achieve synergistic cell killing.