In vitro and in silico evaluation of NF-κB targeted costunolide action on estrogen receptor-negative breast cancer cells--a comparison with normal breast cells.

Costunolide, a sesquiterpene lactone is a plant-derived secondary metabolite found to be present in most of the pharmacologically active herbs, being the cause for their medicinal values. The present study aims to evaluate the cytotoxic effect of costunolide isolated from Costus speciosus rhizome extract on MDA-MB-231 cells and explore its targeted action in comparison with its action on the normal breast cells (MCF 10A). The effect of costunolide on cell viability of the cells was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability assay. The targeted action of the compound was analyzed comparing the effectiveness of the compound to alter the protein expression levels of NF-κB subunits in the normal and the cancer cells using western blotting analysis. In silico studies were performed to predict the targeted interaction of costunolide with the NF-κB subunit proteins. Costunolide inhibited the cell viability of MDA-MB-231 cells in a dose-dependent manner leaving no significant change in the viability of the normal breast cells. The over expressed NF-κB subunits - p65, 52 and 100 in the cancer cells were found to be downregulated when treated with costunolide at an effective dose of 20 and 40 μM costunolide. In silico results provided stable interactions between costunolide and the target proteins, supporting the in vitro results in addition. Thus, costunolide derived from C. speciosus plant source elevates a fresh conviction for its use in breast cancer therapy for its cytotoxic efficacy and non-toxic nature.