I kappa B alpha gene transfer is cytotoxic to squamous-cell lung cancer cells and sensitizes them to tumor necrosis factor-alpha-mediated cell death

Current paradigms in cancer therapy suggest that activation of nuclear fact or-kappa B (NF-kappa B) by a variety of stimuli, including some cytoreducti ve agents, may inhibit apoptosis. Thus, inhibiting NF-kappa B activation ma y sensitize cells to anticancer therapy. thereby providing a more effective treatment for certain cancers. E-1-deleted adenoviral (Ad) vectors encodin g a "superrepressor" form of the NF-kappa B inhibitor I kappa B alpha (AdI kappa B alpha SR) or beta-galactosidase (AdLacZ) were tested alone and in c ombination with tumor necrosis factor-alpha (TNF-alpha) in lune cancer cell s for sensitization of the cells to death. Following transduction with AdI kappa B alpha SR, lung cancer cells expressed I kappa B alpha SR in a dose- dependent manner. Probing nuclear extracts of lung cancer cells with NF-kap pa B-sequence-specifc oligonucleotides indicated that there was a minimal a mount of NF-kappa B in the nucleus at baseline and an expected and dramatic increase in nuclear NF-kappa B following exposure of cells to TNF-alpha. C ontrol E-1-deleted AdLacZ did not promote NF-kappa B activation. Importantl y, AdI kappa B alpha SR-mediated gene transfer resulted in the complete blo ck of nuclear translocation of NF-kappa B by specific binding of its p65/re lA component with transgenic I kappa B alpha SR. At the cellular level, tra nsduction with AdI kappa B alpha SR resulted in increased cytotoxicity in l ung cancer cells as opposed to transduction with equivalent doses of AdLacZ . In addition. whereas the parental cells were resistant to TNF-alpha-media ted cytotoxicity, I kappa B alpha SR-transduced cells could be sensitized t o TNF-alpha. Consequently, AdI kappa B alpha SR transduction followed by ex posure to TNF-alpha uniformly resulted in the death of non-small-cell lung cancer cells. These data suggest that novel approaches incorporating I kapp a B alpha. gene therapy may have a role in the treatment of lung cancer.