Vitamin D and its analogs as anticancer and anti-inflammatory agents.

Vitamin D3 is the precursor of the steroid hormone calcitriol (1α,25-dihydroxyvitamin D3), a potent agonist of the transcription factor vitamin D receptor (VDR). Calcitriol has received large appreciation due to the impact not only on mineral homeostasis, but also on metabolic diseases, immunological disorders, and cancer. A supraphysiological dose of calcitriol is required to reduce the proliferation of cancer cells. However, the dose will lead to calcemic side effects such as hypercalcemia and hypercalciuria. Although several analogs of 1α,25(OH)2D3 have shown potent anticancer or anti-inflammatory activity on cell cultures or in animal models, few vitamin D analogs have been successfully applied in the treatment of cancer or inflammatory diseases. This review will present and discuss vitamin D analogs that have the potential to be used as anticancer or anti-inflammatory agents.