桔梗皂苷D对人乳腺癌细胞体外杀伤效应及机制研究

Viability Inhibition of Human Breast Cancer Cells Treated with Platycodin D in Vitro and the Underlying Mechanism

目的探讨桔梗皂苷D对人乳腺癌细胞体外杀伤效应及机制。方法将人乳腺癌细胞系MCF-7和MDA-MB-231用桔梗皂苷D干预后,采用MTT法检测桔梗皂苷D对这两种乳腺癌细胞系的抑制率;采用流式细胞术检测桔梗皂苷D对MCF-7细胞凋亡的影响;Western blot法检测桔梗皂苷D干预后MCF-7细胞caspase-3、Bcl-2和Bax表达水平。结果 MCF-7细胞抑制率:2.5μg/mL桔梗皂苷D组(8.9±2.4)%,5μg/mL桔梗皂苷D组(24.6±3.6)%,10μg/mL桔梗皂苷D组(39.7±4.1)%,20μg/mL桔梗皂苷D组(64.8±5.2)%,40μg/mL桔梗皂苷D组(82.4±6.5)%;MDA-MB-231细胞抑制率:2.5μg/mL桔梗皂苷D组(5.3±1.7)%,5μg/mL桔梗皂苷D组(17.3±2.9)%,10μg/mL桔梗皂苷D组(28.4±3.5)%,20μg/mL桔梗皂苷D组(50.5±4.0)%,40μg/mL桔梗皂苷D组(71.3±6.1)%,与对照组比较,差异有统计学意义(P均<0.05);MCF-7细胞的凋亡诱导率:5μg/mL桔梗皂苷D组为(9.7±1.6)%,20μg/mL桔梗皂苷D组(29.8±3.1)%,高、低剂量桔梗皂苷D组与对照组比较,差异有统计学意义(P均<0.05);与相同剂量桔梗皂苷D组比较,zVAD-fmk可有效抑制桔梗皂苷D对MCF-7细胞的凋亡诱导效应(P<0.05);桔梗皂苷D能显著降低MCF-7细胞Bcl-2表达水平(0.43±0.07、0.24±0.04 vs 0.78±0.09,P均<0.05),但对Bax表达无影响(0.38±0.05、0.41±0.04 vs0.42±0.05,P>0.05)。结论桔梗皂苷D诱导乳腺癌细胞进入caspase-3依赖的凋亡过程,其机制可能与降低Bcl-2表达,降低Bcl-2/Bax比例有关。

Objective To investigate the anticancer activity of platycodin D in breast cancer cells and the mechanism.Methods Human breast cancer cell lines MCF-7 and MDA-MB-231 were treated with platycodin D.Cell viability was then measured by using the MTT assay.Apoptosis of MCF-7 treated with platycodin D was determined by flow cytometry.The expression of cleaved caspase-3,Bcl-2 and Bax on MCF-7 was detected by western blot.Results The viability inhibition rate of MCF-7 were as follows：8.9%±2.4%in 2.5 μg/mL platycodin D group,24.6%±3.6%in 5 μg/mL platycodin D group,39.7%±4.1%in 10 μg/mL platycodin D group,64.8%±5.2%in 20μg/mL platycodin D group,82.4%±6.5%in 40μg/mL platycodin D group.The viability inhibition rate of MDA-MB-231 were as follows：5.3%±1.7%in 2.5 μg/mL platycodin D group,17.3%±2.9%in 5μg/mL platycodin D group,28.4%±3.5%in 10 μg/mL platycodin D group,50.5%±4.0%in 20μg/mL platycodin D group,71.3%±6.1%in 40μg/mL platycodin D group.Statistical differences was found between MCF-7 and MDA-MB-231 treated with platycodin D group and control group（P〈0.05）.The apoptosis rate of MCF-7 cells was 9.7%±1.6%in 5μg/mL platycodin D group and 29.8%±3.1%in 20μg/mL platycodin D group,which were significantly different from that of control group（P〈0.05）.Compared to the equal dose of platycodin D group,Zvad-fmk significantly inhibited the apoptosis induced by platycodin D（P〈0.05）.Pplatycodin D decreased the expression of Bcl-2 on MCF-7 cells（0.43±0.07 and 0.24±0.04 vs 0.78±0.09,P〈0.05）,while it did not affect the expression of Bax on MCF-7 cells（0.38±0.05 and 0.41 ±0.04 vs 0.42±0.05,P〉0.05）.Conclusion Platycodin D can induce caspase-3-dependant apoptosis of breast cancer cells by down-regulating the expression of Bcl-2 and the ratio of Bcl-2 to Bax.