Combined treatment of breast cancer cell lines with vitamin D and COX-2 inhibitors

Background: Vitamin D is known for its anticancerogenous potential. Prostaglandin E₂ (PGE₂) is a proliferation and inflammation activating agent. The production of PGE₂ is dependent on the activity of cyclooxygenase-2 (COX-2). A link between vitamin D and PGE₂ metabolism was recently shown. Materials and Methods: In MDA-MB-231 and MCF-7 breast cancer cell lines we investigated the influence of calcitriol and the COX-2 inhibitor celecoxib regarding cell growth via MTT test, as well as on the protein and mRNA expression of COX-2 using western blot and qRT-PCR. Results: The proliferation of MCF-7 and MDA-MB-231 was inhibited by both calcitriol and the COX-2 inhibitor celecoxib and even stronger by their combination. Moreover, calcitriol inhibited the COX-2 protein expression in MDA-MB-231, as well as the COX-2 mRNA expression in both cell lines. Conclusion: The combination of calcitriol and celecoxib demonstrated a cooperative growth-inhibiting effect in breast cancer cell lines.