Calcitriol Inhibits Proliferation and Potentially Induces Apoptosis in B16–F10 Cells

Background Melanoma is one of the most aggressive types of cancer and it has shown a remarkable surge in incidence during the last 50 years. Melanoma has been projected to be continuously rising in the future. Therapy for advanced-type melanoma is still a challenge due to the low response rate and poor 10-year survival. Interestingly, several epidemiological and preclinical studies had reported that vitamin D deficiency was associated with disease progression in several cancer types. In vivo and in vitro studies revealed anti-proliferative, anti-angiogenic, apoptosis, and differentiation induction effects of calcitriol in various cancers. However, information on the effects of calcitriol (1,25(OH)2D3) on melanoma is still limited, and its mechanism remains unclear. Material/Methods In the present study, by utilizing B16–F10 cells, which is a melanoma cell line, we explored the anti-proliferative effect of calcitriol using cell viability assay, near-infrared imaging, expression of apoptosis-related genes using real-time polymerase chain reactions (PCR), and the expression of apoptosis proteins levels using western blot. In addition, we also assessed calcitriol uptake by B16–F10 cells using high-performance liquid chromatography (HPLC). Results We found that calcitriol inhibits melanoma cell proliferation with an IC50 of 93.88 ppm (0.24 μM), as shown by cell viability assay. Additionally, we showed that B16–F10 cells are capable of calcitriol uptake, with a peak uptake time at 60 min after administration. Calcitriol was also able to induce apoptosis-related proteins such as caspase-3, caspase 8, and caspase-9. These effects of calcitriol reflect its potential utility as a potent adjuvant therapy for melanoma. Conclusions Calcitriol inhibits cell proliferation and induces apoptosis in B16–F10 cells.