Adenoviral Bak overexpression mediates caspase-dependent tumor killing

One of the most promising strategies in cancer gene therapy is adenoviral transfer of proapoptotic genes. We therefore evaluated the novel strategy of adenovirally overexpressing the proapoptotic Bak gene. Our results showed marked apoptosis in cancer cells in vivo and in vitro after Bak gene transfer via a binary adenoviral vector system. This effect was not seen in a caspase 3-defective cell line (MCF-7) and was abrogated in Bak- sensitive tumors after administration of the caspase inhibitor zDEVD-fmk. Our results suggest that adenoviral-mediated overexpression of Bak provides a novel therapeutic strategy for cancer therapy, but this process appears to be caspase dependent.