Inhibition of NF-κB sensitizes human pancreatic carcinoma cells to apoptosis induced by etoposide (VP16) or doxorubicin

The transcription factor NF-κB has anti-apoptotic properties and may confer chemoresistance to cancer cells. Here, we describe human pancreatic carcinoma cell lines that differ in the responsiveness to the topoisomerase-2 inhibitors VP16 (20 μM) and doxorubicin (0.3 μM): Highly sensitive BxPC-3 and PT45-P1 cells, and Capan-1 and A818-4 cells that were almost resistant to both anti cancer drugs. VP16, but not doxorubicin, transiently induced NF-κB activity in all cell lines, whereas basal NF-κB binding was nearly undetectable in BxPc-3 and PT45-P1 cells, but rather high in Capan-1 and A818-4 cells, as demonstrated by gel-shift and luciferase assays. Treatment with various NF-κB inhibitors (Gliotoxin, MG132 and Sulfasalazine), or transfection with the IκBα super-repressor, strongly enhanced the apoptotic effects of VP16 or doxorubicin on resistant Capan-1 and 818-4 cells. Our results indicate that under certain conditions the resistance of pancreatic carcinoma cells to chemotherapy is due to their constitutive NF-κB activity rather than the transient induction of NF-κB by some anti-cancer drugs. Blockade of basal NF-κB activity by well established drugs efficiently reduces chemoresistance of pancreatic cancer cells and offers the potential for improved therapeutic strategies.