MTMR6激活PI3K/AKT/mTOR信号通路促进肝癌细胞侵袭

Myotubularin-related protein 6 promotes invasion of hepatocellular carcinoma cells by activating the PI3K/AKT/mTOR signaling pathway

目的 探究肌微管素相关蛋白6(myotubularin-related protein 6,MTMR6)对人肝癌细胞(HepG2)侵袭能力的影响及潜在的分子机制。方法 在GEO数据库中通过分析肝癌组织与非癌肝组织的测序结果,筛选出差异表达基因MTMR6,随后从癌症基因组图谱(TCGA)数据库中对MTMR6与通路相关性评分进行Spearman分析,最后通过Genemania数据库分析MTMR6与信号通路蛋白的互作关系。比较MTMR6在人正常肝细胞系(LO-2)和肝癌细胞系(Huh-7和HepG2)中的蛋白表达情况;选取HepG2作为研究对象,沉默或过表达MTMR6基因,运用Transwell实验检测细胞侵袭能力,蛋白免疫印迹实验(Western blot)检测MTMR6、PI3K、p-PI3K、AKT、p-AKT、mTOR、p-mTOR、MMP-2和MMP-9蛋白表达。结果 MTMR6基因在肝癌组织中的表达明显高于癌旁组织,并且MTMR6与PI3K/AKT/mTOR信号通路呈正线性相关(P<0.01),MTMR6与PI3K、AKT、mTOR蛋白之间存在互作关系。与LO-2和Huh-7细胞相比,MTMR6在HepG2细胞中的表达水平明显升高(P<0.01)。将HepG2细胞中MTMR6基因过表达,细胞侵袭能力明显增强(P<0.01),而将HepG2细胞中MTMR6基因沉默,细胞侵袭能力明显下降(P<0.01)。沉默MTMR6基因导致PI3K、AKT、mTOR蛋白的磷酸化水平以及MMP-2和MMP-9表达水平下降(P<0.01),而过表达MTMR6则促进PI3K、AKT、mTOR蛋白的磷酸化水平以及MMP-2和MMP-9表达水平升高(P<0.01)。使用特异性PI3K抑制剂LY294002阻断PI3K/AKT/mTOR通路下调MMP-2、MMP-9表达(P<0.01),但对MTMR6表达无影响。结论 MTMR6通过激活PI3K/AKT/mTOR信号通路促进肝癌细胞发生侵袭。

Objective To explore the effect of myotubularin-related protein 6(MTMR6) on the invasion of hepatocellular carcinoma cell line HepG2 and the potential molecular mechanism.Methods By analyzing the sequencing results of liver cancer tissues and adjacent tissues in Gene Expression Omnibus(GEO) database,MTMR6 gene was screened out,and Spearman analysis was used to analyze the correlation of MTMR6 and pathway in the Cancer Genome Atlas(TCGA) database.Finally,the interaction between MTMR6 and signaling pathway proteins was analyzed with Genemania database.Then the expression of MTMR6 in human normal liver cell line LO-2 and hepatoma cell lines Huh-7 and HepG2 were measured and compared among the cell lines.Then HepG2 cells was selected as the study object.After MTMR6 gene was knocked down or over-expressed in HepG2 cells,Transwell assay was employed to observe invasion ability,and Western blotting was adopted to detect the expression of MTMR6,PI3K,p-PI3K,AKT,p-AKT,mTOR,p-mTOR MMP-2 and MMP-9.Results The expression of MTMR6 was significantly higher in the hepatocellular carcinoma tissues than the paracancer tissues,and it was in a positive linear correlation with PI3K/AKT/mTOR signaling pathway(P<0.01),showing interaction with PI3K,AKT and mTOR.The expression level of MTMR6 was significantly higher in the HepG2 cells than the LO-2 and Huh-7 cells(P<0.01).Over-expression of MTMR6 obviously enhanced invasion ability(P<0.01),while its knockdown decreased the ability(P<0.01) in HepG2 cells.Knockdown of MTMR6 gene also resulted in decreased phosphorylation of PI3K,AKT and mTOR,and expression levels of MMP-2 and MMP-9(P<0.01),while over-expression of MTMR6 promoted the phosphorylation of PI3K,AKT and mTOR,and up-regulated the expression of MMP-2 and MMP-9(P<0.01).In addition,LY294002(a specific PI3K inhibitor) treatment could block the PI3K/AKT/mTOR pathway and down-regulate the expression of MMP-2 and MMP-9(P<0.01),but had no effect on MTMR6 expression.Conclusion MTMR6 may promote the invasion of hepatoma cells through activation of PI3K/AKT/mTOR signaling pathway.