Figure 3: Effect of OPG in breast cancer MCF7 cells. (A) SiRNA knockdown OPG and Rab25 expression in MCF7 decrease OPG secretion. MCF7 cells were transfected with siRNA specific to OPG, Rab25 or non-target siRNA (NT) control. Flesh culture media was placed 24h post-transfection and OPG concentration was measured by Human Osteoprotegerin (OPG)/TNFRSF11B DuoSet purchased from R&D Systems*, p < 0.05 vs NT siRNA control. (B) TRAIL induced cells death was augmented by decreasing expression of OPG and Rab25 in MCF7 cells. a, p < 0.01 vs no drug NT siRNA transfected control, b p < 0.05 vs NT siRNA transfected TRAIL treated samples. (C) QPCR detection of OPG and Rab25 mRNA level in MCF7 Rab25 stably knockdown cells (MCF7 sh Rab25). The OPG and Rab25 expression level in HEY pcDNA was set to 1 for comparison. a, p < 0.01 vs HEY pc DNA control, b, p < 0.05 vs MCF7 shRNA control (MCF7 sh Cont). (D) Addition of exogenous OPG decreased MCF7 cells sensitivity to TRAIL-induced cell death. *, p < 0.05 vs no TRAIL control. (E) OPG and Rab25 mRNA expression in breast cancer cell line with respect to TRAIL sensitivity. *, p < 0.05 vs TRAIL sensitive cells.