Inhibition of nuclear factor-κB by an antioxidant enhances paclitaxel sensitivity in ovarian carcinoma cell line

The objective of this study was to determine whether paclitaxel and a strong antioxidant, pyrrolidinedithiocarbamate (PDTC), can affect the activation of nuclear factor-kappa B (NF-kappa B) in SKOV-3 human ovarian cancer cell line and the effect of these two agents on the growth and apoptosis of the cancer cells. The cells were treated with various concentrations of paclitaxel and/or PDTC at various time intervals. Following treatments, cell growth and apoptosis were determined by 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulphonyl)-2H-tetrazolium (WST-8) (WST) assay and flow cytometry, respectively. Western blot assay was used to determine the nuclear p65 protein and cytoplasmic I kappa B-alpha protein. High doses of PDTC significantly inhibited the growth of SKOV-3 cells and caused apoptosis. Paclitaxel and lower doses of PDTC combined demonstrated additive inhibition of cell growth and increased levels of apoptosis. Treatment of paclitaxel alone showed increased nuclear p65 protein and decreased cytoplasmic I kappa B-alpha protein expression, while pretreatment of PDTC reversed this function. PDTC blocks the paclitaxel-induced activation of NF-kappa B leading to increased chemosensitivity to paclitaxel and enhanced apoptosis. Combining antioxidants and paclitaxel has significant potential to overcome the risk of paclitaxel resistance.