miR-26a抑制ST3GAL6基因介导mTOR信号通路对小鼠Lewis肺癌细胞增殖凋亡的作用机制

目的:探究miR-26a靶向调控ST3GAL6基因介导mTOR信号通路对小鼠Lewis肺癌细胞增殖凋亡的作用机制。方法:构建肺癌小鼠模型，将小鼠分为正常组和模型组；免疫组化检测ST3GAL6在肺组织中的表达情况，qRT-PCR法检测miR-26a在组织中的表达；细胞分为空白组、阴性对照组、miR-26a mimic组、miR-26a inhibitor组、si-ST3GAL6组、miR-26a inhibitor+si-ST3GAL6组和miR-26a mimic+RAD001（mTOR抑制剂）组；qRT-PCR法检测细胞中miR-26a和ST3GAL6 mRNA的表达情况；MTT法和流式细胞术分别检测各组细胞的增殖和凋亡情况；Western blot法测定各组细胞ST3GAL6、p-mTOR、Akt蛋白相对表达量。结果:miR-26a和ST3GAL6在肺癌小鼠肺癌组织中均高表达（均P<0.05）。与空白组相比，miR-26a mimic组ST3GAL6 mRNA及蛋白表达上升，Akt、p-mTOR蛋白表达上升，细胞增殖率上升、凋亡率下降（均P<0.05）；而miR-26a inhibitor组、si-ST3GAL6组和miR-26a inhibitor+si-ST3GAL6组ST3GAL6 mRNA及蛋白表达下调，Akt、p-mTOR蛋白表达下降，细胞增殖率下降、凋亡率上升（均P<0.05）。同时，miR-26a表达在miR-26a mimic组和miR-26a mimic+RAD001组中上升，miR-26a inhibitor组和miR-26a inhibitor+si-ST3GAL6组中下降（均P<0.05）。结论:miR-26a下调ST3GAL6基因，抑制mTOR信号通路活化，抑制肺癌细胞增殖及促进细胞的凋亡。

Mechanism of miR-26a inhibiting ST3GAL6 gene expression on proliferation and apoptosis of Lewis lung cancer cells in mice by mediating mTOR signaling pathway

Objective:To explore the mechanism of miR-26a targeting ST3GAL6 gene-mediated mTOR signaling pathway on the proliferation and apoptosis of Lewis lung cancer cells in mice.Methods:With the establishment of lung cancer，mice were divided into normal group and model group.The expression of ST3GAL6 in lung tissue was detected by immunohistochemistry and the expression of miR-26a was detected by qRT-PCR.Cell groups included blank group，negative control group，miR-26a mimic group，miR-26a inhibitor group，si-ST3GAL6 group，miR-26a inhibitor+si-ST3GAL6 group and miR-26a mimic+RAD001 (mTOR inhibitor) group.The relative expression of miR-26a and ST3GAL6 mRNA was detected by qRT-PCR.The proliferation and apoptosis of cells were detected by MTT and flow cytometry，and the protein expression of ST3GAL6，p-mTOR and Akt protein was measured by Western blot.Results:Both miR-26a and ST3GAL6 were highly expressed in lung cancer tissues of mice (All P<0.05).Compared with blank group，the expression of ST3GAL6 mRNA and protein were increased，the expression of Akt and p-mTOR protein were increased，and cell proliferation increased while apoptosis rate decreased in miR-26a mimic group (All P<0.05).While there were decreased expression of ST3GAL6 mRNA and protein，reduced expression of Akt and p-mTOR protein，increased cell apoptosis rate and inhibited cell proliferation in miR-26a inhibitor group，si-ST3GAL6 group and miR-26a inhibitor+si-ST3GAL6 group (All P<0.05).Meanwhile，the expression of miR-26a was increased in miR-26a mimic group and miR-26a mimic+RAD001 group，and decreased in miR-26a inhibitor group and miR-26a inhibitor+si-ST3GAL6 group (All P<0.05).Conclusion:miR-26a down-regulates ST3GAL6 gene，inhibits the activation of mTOR signaling pathway，inhibits the proliferation of lung cancer cells and promotes cell apoptosis.