Cyclo-Oxygenase 2 Modulates Chemoresistance in Breast Cancer Cells Involving NF-κB

BACKGROUND Breast cancer cells can develop chemoresistance after prolonged exposure to cytotoxic drugs due to expression of the multi drug resistance (MDR) 1 gene. Type 2 cyclo-oxygenase (COX-2) inhibitors reverse the chemoresistance phenotype of a medullary thyroid carcinoma cell line, TT, and of a breast cancer cell line, MCF7, by inhibiting MDR1 expression and P-gp function. AIM investigate the role of prostaglandin (PG) in modulating chemoresistance in MCF7 cells and to explore the involved intracellular mechanisms. METHODS native and chemoresistant MCF7 cells were treated with PGH2 and resistance to Doxorubicin was tested in the presence or absence of COX-2 inhibitors. RESULTS PGH2 restores resistance to the cytotoxic effects of Doxo, with concomitant nuclear translocation of the transcription factor NF-kappaB. CONCLUSIONS COX-2 inhibitors prevent chemoresistance development in breast cancer cells by inhibiting P-gp expression and function by a mechanism that involves PGH2 generation and NF-kappaB activation.