Potentiation of tumor necrosis factor-mediated apoptosis of oral squamous cell carcinoma cells by adenovirus-mediated gene transfer of NF-κB inhibitor

Oral squamous cell carcinoma (SCC) is a malignant tumor which is often resistant to cancer-therapy-mediated apoptosis. The stress-responsive transcription factor nuclear factor kappa B (NF-kappaB), which has been found to be associated with SCC development, plays an essential role in the suppression of tumor necrosis factor (TNF)mediated apoptosis. Here, we report that an adenovirus-mediated gene transfer of NF-kappaB inhibitor, super-repressor I kappa B alpha (Adv-SR-IkappaBalpha), blocked TNF-induced NF-kappaB activation and sensitized oral SCC cells to TNF killing. Additionally, we found that the inhibition of NFkappaB by Adv-SR-IkappaBalpha enhanced TNF-mediated caspase-8 and -3 activation. These results suggest that NF-kappaB activation is a general mechanism by which oral squamous carcinoma cells are resistant to TNF killing and provide a molecular basis for gene therapy of oral cancer by IkappaBalpha gene transfer in vivo.