Effects Of Genistein On Biological Function Of Three - Negative Breast Cancer Cell Line MDA-MB-231 And Its Mechanism

Purpose:To investigate the role of Notch-1 signaling pathway in the growth of triple-negative breast cancer (TNBC).Materials and methods:Notch-1 siRNA was transiently transfected into MDA-MB-231 cells to down-regulate the mRNA expression of Notch-1. The cell proliferation was assessed by MTT assay and the changes in cell apoptosis and cell cycle were evaluated by flow cytometry. In addition, Real-time PCR was used to measure mRNA levels of Notch-1, cyclin B1, Bcl-2 and Bcl-XL and Western blotting was used to measure NF-κB level in cell nucleus.Results:Our study reveals that Notch-1 siRNA can effectively inhibit the expression of Notch-1, with the inhibition rate of 88.6%. The proliferation of MDA-MB-231 cells was markedly inhibited by Notch-1 siRNA with the inhibition rate of 44.7%. The apoptosis rate increases from 3.67% to 13.25% and the percentage of cells at G2 phase increases from 6.27% to 14.28%. Furthermore, our data demonstrates that Notch-1 siRNA, which down-regulates expression of Notch-1, can further down-regulate the expression of NF-κB in nucleus, and the expression of cyclin B1, Bcl-2 and Bcl-XL in MDA-MB-231 cells.Conclusions:Our results suggest that Notch-1 pathway plays a critical role inTNBC. Down-regulation of Notch-1 by siRNA can inhibit the proliferation of MDA-MB-231 cells. Notch-1 may be a novel therapeutic target of TNBC.Purpose:Genistein was reported as a protective factor against breast cancer. However, the molecular mechanism by which genistein elicits its effects on triple-negative breast cancer cells has not been fully elucidated.Materials and methods:In our study, breast cancer cell line MDA-MB-231 was selected to determine the action of genistein on triple-negative breast cancer cells. MTT assay, flow cytometric analysis, siRNA transfection, Western blotting and Activation-Nuclear Translocation assay were used to address the role of NF-κB activity and Notch-1 signaling pathway in the action of genistein on cells.Results:Our study reveals that Genistein elicits a dramatic effect on cell growth inhibition, in a dose-dependent and time-dependent manner. Treatment of MDA-MB-231 cells with 0,5,10, or 20 μM genistein induces apoptosis of 6.78, 18.98,30.45, and 60.64%, respectively. And exposure of MDA-MB-231 cells to genistein also results in G2/M phase accumulation of cells corresponding to 4.93, 12.54,18.93, and 30.95%, respectively. Furthermore, our data demonstrates for the first time that genistein inhibits triple-negative breast cancer cells MDA-MB-231 growth by inhibiting NF-κB activity via Nocth-1 signaling pathway in a dose-dependent manner. We also found that genistein down-regulated expression of cyclin B1, Bcl-2 and Bcl-XL, possibly mediated by NF-κB activation via Notch-1 signaling pathway.Conclusions:Our results suggest that inhibition of NF-κB activity via Notch-1 pathway may be a novel mechanism by which genistein suppresses triple-negative breast cancer cells growth. Further preclinical and clinical studies are wanted to confirm the hypothesis to apply the use of genistein in patients with triple-negative breast cancer.