Estrogen receptor mediated effects of Cimicifuga extracts on human breast cancer cells

Cimicifuga racemosa extracts have long been used to treat female reproductive disorders both in Asia and Europe. Here in this study, we examined the possible estrogen receptor (ER)alpha effects of Cimicifuga heracleifolia var. bifida ethanol extract (C-Ex), which has been used traditionally in Asia, in MCF-7 cells. The activity of C-Ex was characterized in a transient transfection system, using ERa and estrogen-responsive luciferase plasmids in HEK 293 cells and endogenous target genes were studied in MCF-7 cells. C-Ex failed to activate ERalpha and at a concentration of 0.005-0.5 mg/ml as examined by reporter activity. In addition, no statistically significant antiestrogenic activity was observed. However, to our interest, C-Ex enhanced expression of VEGF at 0.5 mg/ml concentration and repressed ERalpha both at the mRNA and protein levels in MCF-7 cells. These results suggested that C-Ex does not activate or inactivate ERalpha in a direct manner, but the extracts may affect factors in ER signal transduction pathway.