Figure 4.

Calcitriol decreases PG synthesis in BCa cells. A, Calcitriol decreases COX-2 mRNA levels in BCa cells. BCa cells were treated with calcitriol as described in Fig. 1A and COX-2 mRNA levels were determined. *, P < 0.05 and ***, P < 0.001 compared with vehicle. B, Calcitriol decreases COX-2 protein levels. Western blot showing COX-2 expression in MDA-MB 231 cells treated with vehicle (Cal−) or 100 nm calcitriol (Cal+) for 48 h. COS-7 cell extracts overexpressing COX-2 and COX-1 protein served as a positive and negative control, respectively. β-Actin was used as a loading control. C, Calcitriol increases 15-PGDH mRNA levels in BCa cells. BCa cells were treated as described in Fig. 1A and 15-PGDH mRNA levels were determined. *, P < 0.05 compared with vehicle. D, Calcitriol decreases PGE₂ levels in BCa cells. MCF-7 and MDA-MB 231 cells were treated with vehicle (Veh) or calcitriol (Cal) at 10 and 100 nm, respectively, in serum-free culture media for 72 h. PGE₂ levels in conditioned media were measured. **, P < 0.01 and ***, P < 0.001 compared with vehicle.