Cytotoxic Effect of Combination Treatment of Vitamin D and Pitavastatin on the MCF7 Breast Cancer Cells

Breast cancer is the most common cancer among women. Several common approaches to cancer management are being used, but many cancer patients develop resistance to chemotherapy drugs. Here we describe the antiproliferative effect of the combination of vitamin D and pitavastatin against breast cancer cells. Aims: To determine the combined cytotoxic effect of both vitamin D and pitavastatin on the MCF7 breast cancer cell line and to study the mechanism of action behind this effect. Methods: In vitro experimental study using the MCF7 estrogen receptor-positive breast cancer cells. The effective doses of the combinations were determined by MTT, and western blotting was used to determine the different protein levels. Results: The 50% inhibitory concentrations (IC50s) of vitamin D and pitavastatin on MCF7 cells were 5.1 μM and 5.5 μM, respectively. However, when the cells were pre-treated with a low dose of vitamin D (1μM) the new pitavastatin IC50 was 1.1 μM. In addition, the combined treatment inhibited the phosphorylation of STAT3 protein in MCF7 cells and increased p53 and p21 protein levels. Conclusion: The combination of pitavastatin and vitamin D showed a synergistic cytotoxic effect by inducing cell cycle arrest and apoptosis.