Objective    To investigate the effect of genistein on the proliferation of breast cancer cell lines

MDA-MB-453(ER

-

HER2-high)

MCF-7(ER

+

HER2-low)

MCF-7/HER2(ER

+

HER2-high)

and observe the role of HER2 in the antiproliferative effect of genistein.     Methods    Breast cancer cell line MCF-7 highly expressing HER-2/neu was constructed by cell transfection

and the successful transfection was confirmed by immunofluorescence cytochemical technology. After treated by genistein (5

1

0

40

70

100

130

160

190

220  mol/L) for 48 h

the 3 cell lines were examined by MTT assay to evaluate the antiproliferative effect of genistein.     Results    The inhibitive effect of genistein on MDA-MB-453 was increased along with the increasing concentration of genistein

and the IC

50

was 100 μmol/L. The proliferation of MCF-7/HER2 and MCF-7 were enhanced upon a low concentration of genistein

but inhibited at a higher concentration (40 μmol/L and 10 μmol/L

respectively).     Conclusion    Genistein could inhibit the proliferation of all 3 breast cancer cell lines within a certain range of concentration through ER-dependent or ER-independent pathways

and HER2 high-expression could attenuate the antiproliferative effect of genistein on ER positive breast cancer cells.