Adenovirus-mediated inhibition of NF-kappaB confers chemo-sensitization and apoptosis in prostate cancer cells.

Acquirement of multi-drug resistance by tumor cells represents a major obstacle in the management of prostate cancer. Such resistance was demonstrated in the androgen-independent DU-145 cells in response to paclitaxel and the mechanisms by which these cell develops resistance was not understood. The objective of this study was to examine whether abrogation of the constitutively active NF-kappaB in the chemoresistant, androgen independent DU-145 prostate cancer cells will enhance their sensitivity to cytototoxic agents. Inhibition of NF-kappaB by a dominant negative super-repressor IkappaB mutant adenoviral construct enhanced the apoptotic potentials of paclitaxel and rhTNF-alpha in these cells. Using reporter assays and RT-PCR analysis, we demonstrate that paclitaxel-induced cell death was associated with an increase in NF-kappaB activation and MDR-1 gene expression. Abrogation of these effects by the dominant negative IkappaB adenoviral construct suggests that induction and/or constitutive activation of NF-kappaB can block the paclitaxel-induced apoptotic signaling pathways in this cell line, possibly by increasing the expression of anti-apoptotic and MDR-1 gene products, leading to development of chemoresistance in these cells. We conclude that inhibition of NF-kappaB activation may have therapeutic implications for prostate cancer.