OBJECTIVETo study the effect of BRCA1 in regulating the proliferation and migration of breast cancer cells stimulated by progesterone.

METHODSBreast cancer MCF-7 and T-47D cell were transfected with a vector containing the coding sequence of BRCA1 (pFlag-CMV2-BRCA1 wt) to induce BRCA1 overexpression or with the empty vector (control). The cells were then stimulated with progesterone, and the cell proliferation and migration were observed using MTT assay and wound healing assay, respectively. The proliferation and migration of MCF-7 cells were also observed following transfection with a small interfering RNA (siRNA) for BRCA1 knockdown or with a scrambled siRNA prior to progesterone stimulation.

RESULTSTransfection with the empty vector and with pFlag-CMV2-BRCA1 wt prior to progesterone stimulation caused significantly different proliferation rates in MCF-7 cells [(114.4∓6.0)% vs (82.1∓3.2)%, P<0.05] and in T-47D cells [(111.3∓4.3)% vs (84.2∓3.5)%, P<0.05], resulting also in significantly different cell migration rates (55.9% vs 15.8% in MCF-7 cells and 44.83% vs 10.43% in T-47D cells). Compared to the scrambled siRNA, BRCA1 siRNA transfection prior to progesterone stimulation significantly increased the proliferation rates [(114.4∓3.05)% vs (125.3∓4.0)%, P<0.05] and migration rate (39.2% vs 69.08%) of MCF-7 cells. The progesterone antagonist RU468 could antagonize the effects of BRCA1 knockdown in enhancing progesterone-stimulated MCF-7 cell proliferation and migration.

CONCLUSIONA decreased BRCA1 expression can enhance progesterone-stimulated tumor cell proliferation and migration in sporadic breast cancer.