微小RNA-9通过TGFβR2/Smad2/Smad3信号轴抑制NSCLC增殖、侵袭和迁移

MicroRNA-9 inhibits proliferation,invasion and migration of non-small cell lung cancer by TGFβR2/Smad2/Smad3 signaling pathway

目的探讨微小RNA-9(miR-9)抑制非小细胞肺癌(NSCLC)增殖、侵袭和迁移的作用及其相关机制。方法采用RT-PCR检测NSCLC组织及其邻近正常肺组织中miR-9的表达。体外实验观察miR-9表达对NSCLC细胞增殖、侵袭和迁移的作用。预测miR-9结合靶基因,通过荧光素酶报告实验证实靶基因。Western blot观察miR-9靶基因及其下游通路的激活及相关蛋白表达情况。结果与正常肺组织相比,NSCLC组织中miR-9的相对表达量降低(P<0.05)。体外实验显示,miR-9的高表达可抑制NSCLC细胞的增殖、侵袭和迁移。靶点预测及荧光素酶报告实验证实miR-9通过结合于转化生长因子β受体2(TGFβR2)mRNA的3′非翻译区结合位点从而抑制其激活。miR-9可以降低TGFβR2下游的Smad2和Smad3的磷酸化水平从而抑制TGF-β的激活。结论 miR-9通过结合并下调TGFβR2,进一步抑制其下游的Smad2和Smad3激活,最终起到抑制NSCLC增殖、侵袭和迁移的作用。

Objective To investigate the effect and underlying mechanism of microRNA-9（miR-9）on inhibiting the proliferation,invasion and migration of non-small cell lung cancer（NSCLC）.Methods RT-PCR was used to detect the expression of miR-9 in NSCLC and tumoradjacent normal lung tissues.The effect of miR-9 on the proliferation,migration and invasion of NSCLC cells was observed in vitro.The miR-9-binding target genes were predicted and confirmed by luciferase reporter assay.Western blot was used to observe the activation and expression of miR-9 target genes and their downstream pathways.Results Compared with normal lung tissues,the relative expression of miR-9 was decreased in NSCLC tissues（P〈0.05）.The experiments in vitro further confirmed that the overexpression of miR-9 inhibited the proliferation,migration,and invasion of NSCLC cells.Target prediction and luciferase reporter experiment confirmed that miR-9 inhibited its activation by binding to the 3′-UTR binding site of TGFβR2 mRNA.Western blot results showed that miR-9 reduced the phosphorylation of Smad2 and Smad3 and inhibited the activation of TGF-β.Conclusion miR-9 can inhibit the activation of Smad2 and Smad3 by binding and down-regulating TGFβR2,and finally inhibit the proliferation,invasion and migration of NSCLC.