Role of nuclear factor of kB in tumor necrosis factor alpha-mediated INS-1 cell apoptosis

OBJECTIVE: To investigate the effect of cytokine tumor necrosis factor alpha(TNFalpha) on pancreatic beta cells apoptosis and the effect of transcription factor nuclear factor of kappa B (NF-kB) on TNFalpha-mediated apoptosis. METHODS: INS-1 cells, a pancreatic beta cell line, were cultured,and recombinant DNA technique, transfection and reinfection technology were used to obtain INS-1/IkBDeltaN cells expressing inhibitor of kB (IkB)alphaDeltaN, mutant IkBalpha (inhibitor of NF-kB). DNA fragmentation assay and fluorescence analysis using a kB-luc reporter gene were applied to observe the NF-kB activity and beta cell apoptosis. RESULTS: NF-kB activity induced by IL-Ibeta was detectable in INS-1 cells but not in INS-1/IkBDeltaN cells. After incubation of the cells with IL-1beta (10 micro g/L), TNFalpha (100 micro g/L) and interferon (IFN)gamma (100 000 U/L) for 48 hours, the combination of TNFalpha and IFNgamma induced apoptosis in INS-1 cells but not in INS-1/IkBDeltaN cells. No apoptosis was observed after incubation of INS-1 cells with IL-1beta or IFNgamma or IL-1beta plus IFNgamma. CONCLUSION: Apoptosis is one of the TNFalpha-induced beta-cell death forms. NF-kB may play an important role in the TNFalpha-mediated beta-cell apoptosis. Inhibition of NF-kB activation protects beta-cells from TNFalpha-induced apoptosis.