Vitamin D inhibits ovarian cancer cell line proliferation in combination with celecoxib and suppresses cyclooxygenase-2 expression

Background: Vitamin D exhibits multiple antiproliferative 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)-1β, 10 μM 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-1β, 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.