海蓬子皂苷甲通过mTOR信号通路诱导MCF7细胞发生自噬

摘要

目的 研究海蓬子皂苷甲(BA)诱导细胞自噬的作用及其机制.方法 采用倒置荧光显微镜法、流式细胞仪法和Western blot法从3个不同角度检测细胞自噬;免疫印迹法检测mTOR信号通路;MTT法检测BA单独或联合3-MA作用后细胞的存活率.结果 BA可诱导MCF7细胞发生自噬,具有剂量依赖性.BA可抑制mTOR磷酸化激活,抑制mTOR下游p70S6K蛋白丝氨酸(Ser)、苏氨酸(Thr)的磷酸化以及4EBP1的磷酸化.且随着BA浓度升高,Akt和p-ERK表达降低.3-MA与10 μmol·L-1 BA联合用药时,细胞存活率明显低于单独使用BA处理的细胞.结论 海蓬子皂苷甲通过抑制Akt和p-ERK蛋白表达,进而抑制mTOR激活,最终诱导人乳腺癌MCF7细胞发生自噬.%Aim To investigate the effects of Bigelovii A on autophagy and its mechanism.Methods Fluorescence microscope,flow cytometry and Western blot were employed to analyze autophagy.Western blot was used to detect the protein expressions of mTOR pathway.MTT colorimetry was used to assay cell viability after treatment with 3-MA and Bigelovii A or Bigelovii A alone.Results Bigelovii A-treated MCF7 cells displayed a dramatic increase in the number of MDC-labeled vesicles and the expressions of LC3-Ⅱ,indicating cell autophagy.Ⅰt was proved that in MCF7 cells,Bigelovii A inhibited mTOR signaling by decreasing Akt and p-ERK.Consistently,Bigelovii A decreased phosphorylation levels of mTOR,p70S6K (Ser371,Thr389) and 4EBP1 proteins.Inhibiting Bigelovii Ainduced autophagy with the autophagy inhibitor 3-methyladenine significantly decreased cell viability,which suggested that Bigelovii A-induced autophagy played a pro-survival role.Conclusion Bigelovii A is likely to induce autophagy through inhibiting mTOR pathway.