title: Effects of the dietary phytoestrogen biochanin A on cell growth in the mammary carcinoma cell line MCF-7.
abstract: Studies of the dietary phytoestrogen biochanin A on cell proliferation of the cultured estrogen responsive cells human breast carcinoma MCF-7 showed that biochanin A exhibits biphasic regulation on MCF-7 cells. At concentrations of less than 10 microg/mL, cells respond to biochanin A by increasing cell growth and de novo DNA synthesis. The addition of biochanin A at concentrations of greater than 30 microg/mL significantly inhibited cell growth and DNA synthesis in a dose-dependent fashion, resulting in an IC(50) value of 40 microg/mL. The reversibility of these inhibitory effects by biochanin A appears also to be concentration dependent. Cells previously treated with high concentrations (>60 microg/mL) of biochanin A did not regain normal growth after treatment ceased. Biochanin A was cytostatic at low concentrations (<40 microg/mL) and cytotoxic at higher concentrations. Upon exposure to 100 microg/mL of biochanin A, cell morphology was severely altered, cell volume decreased, and condensation of cell components was clearly noticeable. In addition, biochanin A damaged cell membranes by increasing membrane permeability. These results suggest possible molecular and cellular mechanisms of the action of dietary phytoestrogens on estrogen target cells.
authors.affiliation: Department of Animal Sciences, National Taiwan University, Taipei, Taiwan, People's Republic of China.
authors.forename: J T
authors.initials: JT
authors.lastname: Hsu
authors.forename: H C
authors.initials: HC
authors.lastname: Hung
authors.forename: C J
authors.initials: CJ
authors.lastname: Chen
authors.forename: W L
authors.initials: WL
authors.lastname: Hsu
authors.forename: C
authors.initials: C
authors.lastname: Ying