Calcitriol Combined With Platinum-based Chemotherapy Suppresses Growth and Expression of Vascular Endothelial Growth Factor of SKOV-3 Ovarian Cancer Cells

Aim: To evaluate the effects of the combination of calcitriol and chemotherapy and to identify the molecular mechanisms underlying the effect of calcitriol on ovarian cancer cells. Materials and Methods: SKOV-3 cells were treated with calcitriol and cisplatin, and their effects alone and in combination in a dose-dependent manner were compared. Cell viability, cell proliferation, and apoptosis were assessed using the following assays: PrestoBlue, intracellular adenosine triphosphate, caspase-3/7 activity, annexin V, and immunoblotting, respectively. Results: Calcitriol alone caused dose-dependent inhibition of cell survival and proliferation, and induced apoptotic cell death of SKOV-3 cells. We confirmed that the expression of vitamin D receptor was increased in a dose-dependent manner by calcitriol. Combination treatment using calcitriol at a physiological concentration of 10-100 nM plus cisplatin significantly suppressed cell survival and induced apoptosis. Furthermore, when calcitriol was administered alone, the activity of vascular endothelial growth factor decreased in a dose-dependent manner, and when combined with cisplatin, activity was more suppressed. Conclusion: In SKOV-3 ovarian cancer cells, calcitriol plus cisplatin exerted greater antiproliferative, apoptotic, and anti-angiogenic effects than cisplatin alone. Adding calcitriol to platinum-based chemotherapy might be beneficial to patients with ovarian cancer.