RETRACTED: Formononetin promotes proliferation that involves a feedback loop of microRNA-375 and estrogen receptor alpha in estrogen receptor-positive cells (Retracted Article)

Formononetin is an O-methylated isoflavone that is isolated from the root of Astragalus membranaceus, and it has antitumorigenic effects. Our previous studies found that formononetin triggered growth-inhibitory and apoptotic activities in MCF-7 breast cancer cells. To further investigate the potential effect of formononetin in promoting cell proliferation in estrogen receptor (ER)-positive cells, we used in vivo and in vitro studies to elucidate the possible mechanism. ER-positive cells (HUVEC, MCF-7) were treated with formononetin. The CCK8 assay, Hoechst 33258, and flow cytometry were used to assess cell proliferation and apoptosis. mRNA levels of ER, Bcl-2, and miR-375 were quantified using real-time polymerase chain reaction. ER, p-Akt, and Bcl-2 expression was determined using Western blot. Compared with the control, low formononetin concentrations (2-6M) stimulated ER-positive cell proliferation (HUVEC, MCF-7). The more sensitive HUVEC cells were used to study the relevant signaling pathway. After treatment with formononetin, ER, miR-375, p-Akt, and Bcl-2 expression was significantly upregulated. The proliferative effect of formononetin was also blocked by a miR-375 inhibitor or raloxifene pretreatment. Additionally, in the in vivo studies, uterine weight in ovariectomized mice treated with formononetin increased significantly, but the weight dramatically decreased with raloxifene or miR-375 inhibitor pretreatment before formononetin. This study demonstrated that formononetin promoted ER-positive cell proliferation through miR-375 activation and this mechanism is possibly involving in a miR-375 and ER feedback loop. (c) 2015 Wiley Periodicals, Inc.