Combination therapy of calcitriol inhibits the proliferation of breast cancer cells: new concept of nonclassical function of calcitriol.

Objectives: To evaluate the anticancer effects of calcitriol and cholecalciferol against different cell lines of breast cancer in monotherapy settings and in combination with raloxifene.
Methods: The antiproliferative, anti-migratory, and apoptotic induction effects were assessed by MTT, wound healing, and flow cytometry assays, respectively.
Results: Calcitriol and cholecalciferol exhibited antiproliferative effects against T47D, MCF-7, and MDA-MB-231 in a time and concentration-dependent manner. The IC ₅₀ values of calcitriol were in the range of 0.05-0.25 μM while that for cholecalciferol were in the range of 3-100 μM. Furthermore, the results showed that calcitriol and cholecalciferol exhibited anti-migratory effects on MDA-MB-231, an apoptotic induction effect on MCF-7 cells, and a synergistic effect when combined with raloxifene.
Conclusions: Calcitriol and cholecalciferol exhibited anticancer effects and may be used as chemosensitizers.
(© 2021 Walter de Gruyter GmbH, Berlin/Boston.)