和厚朴酚通过mTOR信号通路诱导肺癌A549细胞自噬

目的:探讨和厚朴酚(honokiol)对人肺腺癌A549细胞自噬的诱导作用及可能的作用机制。方法:体外培养A549细胞,加入不同浓度(0、10、20、40、60和80μmol/L)的honokiol处理48 h,MTT法检测honokiol对细胞活力的影响;吖啶橙染色观察细胞酸性自噬泡情况;Western blot法检测honokiol及联合自噬抑制剂3-甲基腺嘌呤(3-MA)作用后对自噬相关蛋白LC3及相关的信号通路mTOR蛋白表达的变化。结果:Honokiol剂量依赖地抑制肺癌A549细胞的活力(P<0.05)。Honokiol处理肺癌A549细胞能显著增加细胞内发出亮红色荧光的酸性自噬泡的比例。在40μmol/L的honokiol作用下肺癌A549细胞中LC3-Ⅱ蛋白表达水平显著升高(P<0.01),3-MA作用则显著降低。Honokiol可显著降低p-mTOR蛋白表达水平(P<0.01),而联合3-MA作用后则使p-mTOR蛋白水平显著升高(P<0.01),mTOR总蛋白表达水平均无显著变化。结论:Honokiol可诱导肺癌A549细胞自噬,其机制可能与抑制mTOR信号通路相关。

Honokiol induces autophagy by inhibiting mTOR signaling pathway in lung cancer A549 cells

AIM: To investigate whether honokiol induces the autophagy of human lung cancer A549 cells and to explore its mechanism. METHODS: The A549 cells were cultured in vitro, and treated with honokiol at different concentrations(0, 10, 20, 40, 60 and 80 μmol/L) for 48 h. MTT assay was performed to analyze the effect of honokiol on the viability of the A549 cells. The formation of autophagosome was observed by staining with acridine orange under fluorescence microscope. The protein levels of autophagy-associated protein LC3, mTOR and p-mTOR in the A549 cells treated with honokiol, or combined with autophagy inhibitor 3-methyladenine(3-MA) were determined by Western blot. RESULTS: Honokiol significantly inhibited the viability of A549 cells in a dose-dependent manner(P<0.05). The number of the intracellular acidic autophageic vacuoles with bright red fluorescence was significantly increased after honokiol treatment. The protein level of LC3-II/LC3-I in the A549 cells was significantly enhanced after honokiol(40 μmol/L) treatment, and the ratio of LC3-II/LC3-I was significantly decreased by treatment with 3-MA(P<0.05). Furthermore, treatment with honokiol(40 μmol/L) in the A549 cells for 48 h also resulted in significant down-regulation of phosphorylated form of mTOR(P<0.01), while the total protein level was not changed. CONCLUSION: Honokiol significantly inhibits the growth of lung cancer A549 cells and induces the autophagy, which may be correlated with inhibition of mTOR signaling pathway.