雷公藤甲素通过ERK通路诱导肺癌A549细胞自噬

目的:研究雷公藤甲素(tripchlorolide,TP)对肺癌A549细胞活力及自噬的影响,并初步探讨其作用机制。方法:应用TP作用于肺癌A549细胞后,MTT法检测细胞活力;吖啶橙染色(AO)法在荧光显微镜下观察细胞自噬状态;GFP-LC3质粒转染实验观察细胞胞质中绿色点状聚集的自噬小体;Western blot法检测自噬相关蛋白LC3-Ⅱ的表达情况及有关的信号通路ERK蛋白水平的变化。结果:TP可以显著抑制肺癌A549细胞的增殖(P0.05),并呈一定的剂量-时间依赖关系。TP作用于肺癌A549细胞48 h后,细胞内酸性滤泡染成亮红色荧光比例增多。GFP-LC3转染实验结果显示在100 nmol/L TP处理后,细胞胞质中出现绿色点状聚集的自噬小体,而正常培养组极少细胞有自噬小体形成;同时转染GFP-control质粒的细胞在100 nmol/L TP处理及正常培养条件下均未观察到点状聚集的自噬小体产生。TP作用于肺癌A549细胞48 h后,与对照组相比,100 nmol/L TP组LC3-Ⅱ蛋白表达水平显著升高(P0.01),同时p-ERK/ERK蛋白水平也显著升高(P0.01);与100 nmol/L TP组相比,TP+3-MA组LC3-Ⅱ蛋白表达水平显著下降(P0.01),同时p-ERK/ERK蛋白水平也显著下降(P0.01)。结论:TP可显著抑制肺癌A549细胞活力并诱导细胞发生自噬,这种作用可能与影响ERK的磷酸化有关。

Tripchlorolide activates p-ERK and induces autophagy in lung cancer A549 cells

AIM: To investigate the effects of tripchlorolide (TP) on proliferation and autophagy of human lung cancer A549 cells, and explore its mechanism. METHODS: MTT assay was performed to analyze the effect of TP on the viability of human lung cancer A549 cells. The A549 cells were treated with TP, and their autophagy was observed under the fluorescence microscope through acridine orange staining. Green fluorescence spots were observed by fluorescence microscopy through GFP-LC3 plasmid transfection experiment. The levels of LC3 and p-ERK in the A549 cells after TP treatment were determined by Western blot. RESULTS: The viability of human lung cancer A549 cells was significantly inhibited by TP in a dose-time dependent manner (P<0.05). The number of the intracellular acidic follicles dyed with bright red fluorescence was significantly increased after TP treatment in A549 cells. The number of green dot-like congregate autophagosomes in cell cytoplasm was significantly increased after TP treatment in the A549 cells transfected with GFP-LC3 plasmid, while the normal treatment only induced a few cells with autophagosome formation. At the same time, we did not observe the dot-like congregate autophagosomes after TP treatment in the A549 cells transfected with GFP-control plasmid. Compared with control group, the expression of LC3-Ⅱ protein was up-regulated in A549 cells after TP treatment (P<0.01). Furthermore, treatment with TP in A549 cells for 48 h also led to a significant upregulation of phosphorylated form of ERK (P<0.01). In contrast, no significant change in the levels of total ERK protein was observed. Compared with 100 nmol/L TP group, TP+3-MA group down-regulated the protein levels of LC3-Ⅱ (P<0.01) and p-ERK (P<0.01) in the A549 cells. CONCLUSION: TP significantly inhibits the growth of A549 lung cancer cells and induces the autophagy, which may be correlated with upregulation of p-ERK protein.