Evaluation of the potential anticancer activity of different vitamin D metabolites on colorectal and breast cancer cell lines.

Objectives: Vitamin D is very important for calcium and mineral metabolism, and many hypotheses appear to link sunlight exposure with cancer risk and prognosis. As many studies supported the antitumor effect of vitamin D we wanted to investigate the potential effect of multiple vitamin D metabolites.

Methods: This study compared the anticancer effect of three inactive forms of vitamin D which are; cholecalciferol, alfacalcidol, and calcifediol on two human cancer cell lines colorectal cancer (CaCo II) and breast cancer (MCF-7). All were examined after 24, 48, and 72 h continuous exposure using a colorimetric assay (MTT) seeded in 96-multiwell plates. Doxorubicin anticancer used as a standard agent for comparison, while normal skin fibroblast cells (HDFa) was used as our negative control. IC values were calculated as indication of antitumor effect.

Results: Broad-spectrum of cytotoxicity with IC values ranging from 4 to 200 μM were found. Alfacalcidol was the most potent cytotoxic agents on colorectal cancer (CaCo II) and breast cancer (MCF-7) compared to cholecalciferol, and calcifediol. Both, alfacalcidol and calcifediol were more cytotoxic than cholecalciferol on the tested cell lines as they are partially active metabolites. Breast cancer (MCF-7) was the most sensitive to all metabolites at all-time intervals with the best IC values of 4.35 μM ± 1.06 after 72 h continuous exposure of alfacalcidol.

Conclusions: Vitamin D metabolites are a potential option for cancer treatment along with or an alternative to chemo-therapeutics although extensive preclinical studies are required to prove this effect.