The Mechanism of Calcitriol in Cancer Prevention and Treatment

Jiguang      Ma; Zhenhua      Ma; Wei      Li; Qingyong      Ma; Jian      Guo; Ang      Hu; Rong      Li; Fengfei      Wang; Suxia      Han

Abstract

Calcitriol (1, 25-dihydroxyvitamin D₃) is the most biologically active metabolite derived from the secosteroid hormone vitamin D. Apart from its calcium homeostatic effects, epidemiological studies have shown that reduced serum calcitriol levels are associated with an increased risk of some types of cancer. Numerous recent epidemiological and experimental studies have reported that it elicits anti-proliferative, apoptotic and differentiation effects in several malignant cell types. The inhibition of calcitriol results in reduced effects of anticancer drugs. Results from a number of clinical trials revealed that sufficient dosing and exposure to calcitriol is critical for achieving antitumor effects during intermittent regimens. This review summarizes the role of calcitriol in anticancer therapy and the progress in understanding its mechanism.

Keywords: Anti-proliferative, apoptosis, calcitriol, cancer prevention, chemotherapeutic agents, clinical trial, differentiation, retinoblastoma, signaling pathways, VDR.