Inhibition of NF-κB expression by RNA interference increases HCT116/3-6 and M10 cell sensitivity to TMZ. (A) The cells were mock transfected (M) or subjected to two sequential transfections with 100 nM scrNFp65 (Scr) or siNFp65 (siNF). Seven days after the second transfection, whole cell extracts were prepared and analyzed for RelA content by immunoblotting (see legend of Figure 2). The results are representative of two independent experiments. (B), (C) The cells were mock transfected or subjected to two sequential transfections with 100 nM scrNFp65 or siNFp65. Twenty-four hours after the second transfection, the cells were incubated with the indicated concentrations of TMZ+10 μM BG or with BG alone as a control. Proliferation was evaluated after 6 days of drug exposure by the MTT assay. Data are expressed in terms of percentage of growth of TMZ-treated cells with respect to control cells. Each value represents the mean of four independent experiments performed with quadruplicate samples. Bars, SEM. **p<0.01, and *p<0.05, according to Student’s t test, comparing TMZ IC50 values of siNFp65-transfected cells with those of mock-transfected or scrNFp65-transfected cells. The difference between TMZ IC50 values of scrNFp65 and those of mock-transfected cells was not statistically significant.