Abstract: Objective:To observe the effect of phytoestrogens (genistein,Gen,daidzein,Dai,quercetin,Que,and curcumin,Cur) on DNA damage and proliferation of MCF-7 breast cancer cells. Methods: MCF-7 breast cancer cells were cultured with 3,9,27 and 54 μmol/L Gen or Dai or Que or Cur on 24,48 or 72 h. The proliferation and DNA damage of MCF-7 breast cancer cells were observed by MTT test and single cell gel electrophoresis assay (SCGE). Results: The proliferation of MCF-7 breast cancer cells significantly increases when they are treated with Que or 3 μmol/L Gen or Dai or Cur,but it significantly decreases when the MCF-7 breast cancer cell are treated with 54 μmol/L Gen or Cur. The comet tail length (CTL) in MCF-7 breast cancer cells significant increases when they are treated with 27 μmol/L and 54 μmol/L Gen or Cur and show dose-response and time-response relationships,but it does not significanly change when the MCF-7 breast cancer cell are treated with Dai or Que. Conclusion: 27 μmol/L and 54 μmol/L Gen or Cur can induce DNA damage and inhibits the proliferation of MCF-7 breast cancer cells. Dai or Que does not cause DNA damage and promotes the proliferation of MCF-7 breast cancer cells at the low concentration of Dai.

Key words: DNA damage, breast cancer cells, phytoestrogens, proliferation