中文摘要：

目的观察人参皂苷Rg3对乳腺癌细胞MDA-MB-231增殖的影响,并探讨其机制。方法取处于对数生长期的MDA-MB-231,加入不同终浓度（50、100、200、400、600μmol/L）人参皂苷Rg3,以不加人参皂苷Rg3为对照。MTT法检测细胞生长情况;Western blot法检测细胞中细胞周期蛋白E（Cyclin E）及细胞分裂周期蛋白25A（CDC25A）表达水平。结果低浓度（≤200μmol/L）的人参皂苷Rg3可促进MDA-MB-231增殖,高浓度（≥400μmol/L）的人参皂苷Rg3则抑制其增殖。与对照细胞比较,低浓度人参皂苷Rg3处理的细胞中Cyclin E及CDC25A的表达增高,高浓度处理者Cyclin E及CDC25A的表达下降（P均〈0.01）。结论高浓度人参皂苷Rg3在体外对乳腺癌细胞的生长具有抑制作用,其机制可能与抑制细胞周期关键蛋白Cyclin E及CDC25A的表达有关。

英文摘要：

Objective To investigate the effects of ginsenoside Rg3 on cell proliferation of breast cancer cell line MDA-MB-231 and the possible mechanism involved.Methods MDA-MB-231 cells at logarithmic growth phase were obtained,and were cultured with ginsenoside Rg3 of different concentrations（50、100、200、400、600 μmol/L）.Cells cultured without ginsenoside Rg3 were served as controls.The proliferation of cells were detected by MTT assay,and the expression of Cyclin E and CDC25A was examined by Western blot,respectively.Results The growth rates on MDA-MB-231 cells treated with ginsenoside Rg3 of low concentration（≤200 μmol/L）increased,but those treated with ginsenoside Rg3 of high concentration（≥400 μmol/L）growed more slowly,compared with control group.The expression of cellular Cyclin E and CDC25A rose when exposed to ginsenoside Rg3 of low concentration（≤200 μmol/L）while declined when exposed to ginsenoside Rg3 of high concentration（≥400 μmol/L）.Conclusions Ginsenoside Rg3 of high concentration（≥400 μmol/L）can inhibit the growth of MDA-MB-231.This effect may involve its suppression of cell-cycle related protein Cyclin E and CDC25A.