The role of IkappaBalpha in TNF-alpha-induced apoptosis in hepatic stellate cell line HSC-T6.

To investigate the role of NF-kappaB in TNF-alpha induced apoptosis in HSC-T6, a mutant IkappaBalpha was transfected into HSC-T6 cells by lipofectin transfection technique and its transient effect was examined 48 h after the transfection. The activation of NF-kappaB was detected by immune fluorescence cytochemistry and Western blotting with anti-p65 antibody. The apoptosis and the rate of inhibition by TNF-alpha in both transfected and untransfected HSC-T6 cells were measured respectively by FAC-Scan side scatter analysis and MTT methods. Our results showed that TNF-alpha could activate NF-kappaB in untransfected cells but not in transfected HSC-T6 cells. The percentage of apoptosis in transfected cells were significantly higher than that in the untransfected ones (P<0.01) and it was also true of the inhibition rate (P<0.01). It is concluded that the resistance of HSC-T6 towards apoptosis induced by TNF-alpha can be mediated by NF-kappaB activation. The inhibition of NF-kappaB activation by mutant IkappaBalpha can attenuate the resistance of HSC-T6 cells and increase its sensitivity to TNF-alpha.