Research Progress on the Roles of Vitamin D3 in Gastrointestinal Cancer

Vitamin D3 is a steroid hormone. Its main functions include regulating calcium and phosphate metabolism, maintaining normal blood calcium levels, regulating bone metabolism, and regulating the physiological functions of many cells. Recent epidemiological studies suggested that vitamin D deficiency correlates with the risk of gastrointestinal cancer and a poor prognosis in cancer patients. Vitamin D3 has demonstrated anti-tumor activities, including reducing tumor cell proliferation, inducing apoptosis, and inducing cell cycle arrest in gastrointestinal cancer. Further studies showed that vitamin D3 can enhance the effects of chemotherapeutic drugs to induce apoptosis and inhibit the proliferation of gastrointestinal cancer cells. Vitamin D3 analogs also exhibit anti-tumor activity, and generally have fewer side effects than vitamin D3. This review describes the molecular characteristics and anti-cancer mechanisms of vitamin D3 and its analogs in gastrointestinal cancer.