Inhibition of the transcription factor nuclear factor-κB by adenoviral- mediated expression of IκBαM results in tumor cell death

Background. The activation of transcription factor nuclear factor-κB (NF-κB) by extracellular stimuli has been shown to protect cells from apoptotic cell death. Inhibition of NF-κB activity should result in increased tumor cell killing in response to apoptotic stimuli. This study evaluated the effect of inhibition of NF-κB on a series of sarcoma and normal cell lines. Methods. Human sarcoma cell lines (HT1080, SKLMS-1, and MFH) and normal cell lines (NLF and BSMC) were infected with an adenoviral dominant-negative mutant Ad5IκBαM in vitro. Control cells were infected with the empty adenoviral vector and mock-infected with media alone. Viable cell counts were determined by microscopic evaluation on days 1 to 6 after infection. Cell proliferation was determined at 48 hours by MTT (1-[4,5- dimethylthiazol-2-yl]-3,5-dephenylformazan) assay. Results. All cell lines showed evidence of successful adenoviral infection as evidenced by the infection of all cell lines with the adenoviral marker gene Ad5 LacZ. All the tumor cells were found to have a significant decrease in cell viability and proliferation after treatment with the Ad5IκBαM gene compared with both mock-infected cells and cells infected with empty vector (P < .0001). The normal cell lines, although able to be successfully infected, did not show a significant decrease in cell viability or proliferation with adenoviral- mediated IκBαM infection. Conclusions. Inhibition of NF-κB through adenoviral-mediated infection of the dominant-negative inhibitor IκBαM resulted in a significant decrease in tumor cell viability and proliferation while having no deleterious effect on normal cell lines. The Ad5IκBαM gene therefore could be potentially used as a clinical treatment for patients with soft-tissue sarcoma.