NF-κB transcription factor induces drug resistance through MDR1 expression in cancer cells

Abstract

The ubiquitous NF-B transcription factor has been reported to inhibit apoptosis and to induce drug resistance in cancer cells. Drug resistance is the major reason for cancer therapy failure and neoplastic cells often develop multiple mechanisms of drug resistance during tumor progression. We observed that NF-B or P-glycoprotein inhibition in the HCT15 colon cancer cells led to increased apoptotic cell death in response to daunomycin treatment. Interestingly, NF-B inhibition through transfection of a plasmid coding for a mutated IB- inhibitor increased daunomycin cell uptake. Indeed, the inhibition of NF-B reduced mdr1 mRNA and P-glycoprotein expression in HCT15 cells. We identified a consensus NF-B binding site in the first intron of the human mdr1 gene and demonstrated that NF-B complexes could bind with this intronic site. Moreover, NF-B transactivates an mdr1 promoter luciferase construct. Our data thus demonstrate a role for NF-B in the regulation of the mdr1 gene expression in cancer cells and in drug resistance.