Vitamin D Inhibits Ovarian Cancer Cell Line Proliferation in Combination with Celecoxib and Suppresses Cyclooxygenase-2 Expression

Background: Vitamin D exhibits multiple anti-proliferative and pro-differentiating actions. Prostaglandin(PG)E2 is a tumor-promoting tissue hormone anabolized by cyclooxygenase-2 (COX-2). Recently, a link between the PG and vitamin D metabolism was reported. Materials and Methods: The influence of calcitriol and celecoxib on the proliferation of ovarian cancer cell lines was measured and the impact of calcitriol on the protein and mRNA expression of COX-2 was quantified by western blot and qRT-PCR, respectively. Results: After COX-2 induction with interleukin (IL)-1 beta, 10 mu M celecoxib did not significantly inhibit the proliferation of OVCAR-3 cells, whereas calcitriol showed such an effect; however, the combination of the two substances had an additive influence. After induction by IL-1 mu, calcitriol inhibited the COX-2 protein, as well as its mRNA expression significantly in OVCAR-3 and SKOV-3 cells. Conclusion: These data suggest a correlation between PG and vitamin D metabolism in their anti-tumorigenic activity in ovarian carcinomas.