Suppression of vitamin D metabolizing enzyme CYP24A1 provides increased sensitivity to chemotherapeutic drugs in breast cancer

Vitamin D is an essential nutrient for the human body that plays an important role in homeostasis and contributes to cell fate decision including proliferation, differentiation and cell viability. Accumulated epidemiological data suggest a relationship between vitamin D deficiency and carcinogenesis in various organs. However, the underlying mechanism remains to be further clarified. In this study, we showed that vitamin D metabolizing enzyme CYP24A1 promotes the oncogenic property of breast carcinoma cells. In addition, expression of CYP24A1 is elevated in invasive breast carcinoma and decreases the overall survival. Importantly, CYP24A1 suppression significantly enhances cell death sensitivity to two pharmacologically different acting anticancer drugs, cisplatin and gefitinib. The results of our study suggest the possibility of CYP24A1-inhibiting therapy for breast malignancy.