[目的]研究人参皂甙Rg3对人乳腺癌MDA-MB-231细胞生长的抑制作用及其机制.[方法]采用MTT比色法检测人参皂甙Rg3对人乳腺癌MDA-MB-231细胞生长的抑制作用.利用流式细胞仪检测细胞凋亡及周期变化.建立人乳腺癌MDA-MB-231细胞裸鼠移植瘤模型,观察不同浓度的人参皂甙Rg3对裸鼠的体质量及肿瘤增殖抑制率的影响.采用Western blot方法检测肿瘤组织中procaspase-3和procaspase-9蛋白表达水平.[结果]人参皂甙Rg3可明显抑制人乳腺癌MDA-MB-231细胞的生长(P<0.05),且抑制作用呈剂量和时间依赖性;明显促进MDA-MB-231细胞凋亡(P<0.05),可将细胞周期阻滞于G0/G1期.人参皂甙Rg3对人乳腺癌细胞体内的增长具有明显的抑制作用,与对照组比较,人参皂甙Rg3各浓度组proCaspase-3和proCaspase-9蛋白表达水平均明显降低(P<0.05).[结论]人参皂甙Rg3在体内和体外均可抑制人乳腺癌MDA-MB-231细胞生长,机制认为可能与诱导细胞凋亡、改变细胞周期和Caspase-3,Caspase-9活化有关系. [Objective] To study the inhibitory effect of ginsenoside Rg3 on the growth of human breast cancer MDA-MB-231 cells and its mechanism. [Methods] MTT assay was used to detect the inhibitory effect of ginsenoside Rg3 on the growth of human breast cancer MDA-MB-231 cells .Methods Flow cytometry was used to detect apoptosis and cycle changes.Methods The nude mice model of human breast cancer MDA-MB-231 cells was established and the effects of different concentrations of ginsenoside Rg3 on the body weight and tumor growth inhibition rate .The expression of procaspase-3 and procaspase-9 in tumor tissues were detected by Western blot. [Results] Ginsenoside Rg3 could significantly inhibit the growth of human breast cancer MDA-MB-231 cells (P <0.05) and inhibit In a dose-and time-dependent manner, significantly promoted the apoptosis of MDA-MB-231 cells (P <0.05), and blocked the cell cycle in G0 / G1 phase.Ginsenoside Rg3 significantly inhibited the growth of human breast cancer cells (P <0.05). [Conclusion] Ginsenoside Rg3 could inhibit the proliferation of human breast cancer cell line MDA-MB-231 in vitro and in vivo.Conclusion: Ginsenoside Rg3 can inhibit the expression of pro- MB-231 cell growth, the mechanism that may be induced Apoptosis, cell cycle, and Caspase-3, Caspase-9 activation relationship.