microRNA-200a downregulation in human glioma leads to Gαi1 over-expression, Akt activation, and cell proliferation
microRNA-200a downregulation in human glioma leads to Gαi1 over-expression, Akt activation, and cell proliferation
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人类神经胶质瘤中 microRNA-200a 的下调导致 Galphai1 过度表达、Akt 激活和细胞增殖。
DOI：
10.1038/s41388-018-0184-5
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发表时间：
2018-05-01
期刊：
影响因子：
8
通讯作者：
Cao, Cong
中科院分区：
文献类型：
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作者：
Liu, Yuan-yuan;Chen, Min-Bin;Cao, Cong
我们之前发现了G蛋白α抑制亚基1 （G α i1）在通过受体酪氨酸激酶（rtk）介导PI3K-Akt信号传导中的关键作用。在此，我们检测了G α i1在人类胶质瘤中的表达及其生物学功能。在人胶质瘤组织中，G α i1 mRNA和蛋白的表达显著上调，这与抗G α i1 miRNA: microRNA-200a （miR-200a）的下调相关。在已建立的（A172/U251MG细胞系）和原代（患者来源的）人胶质瘤细胞中强制表达miR-200a导致G α i1下调、Akt失活和增殖抑制。通过shRNA降低G α i1表达、显性负突变体干扰或G α i1完全缺失均可抑制Akt的激活和细胞增殖。值得注意的是，当G α 1沉默或突变时，miR-200a无法抑制胶质瘤细胞的增殖。在人类胶质瘤细胞和组织中的共免疫沉淀研究表明，G α i1与多种rtk （EGFR、PDGFR α和FGFR）和适配器蛋白Gab1形成复合物。在体内，G α 1 shRNA或miRNA-200a的表达在很大程度上抑制了裸鼠皮下和原位胶质瘤异种移植物的生长。综上所述，miR-200a在人胶质瘤中下调可导致G α i1过表达、Akt活化和胶质瘤细胞增殖。
We previously identified a pivotal role for G protein alpha inhibitory subunit 1 (G alpha i1) in mediating PI3K-Akt signaling by receptor tyrosine kinases (RTKs). Here, we examined the expression and biological function of G alpha i1 in human glioma. G alpha i1 mRNA and protein expression were significantly upregulated in human glioma tissues, which correlated with downregulation of an anti-G alpha i1 miRNA: microRNA-200a ("miR-200a"). Forced-expression of miR-200a in established (A172/U251MG lines) and primary (patient-derived) human glioma cells resulted in G alpha i1 downregulation, Akt inactivation and proliferation inhibition. Reduction of G alpha i1 expression by shRNA, dominant negative mutant interference, or complete G alpha i1 depletion inhibited Akt activation and cell proliferation. Notably, miR-200a was unable to inhibit glioma cell proliferation when G alpha i1 was silenced or mutated. Co-immunoprecipitation studies, in human glioma cells and tissues, show that G alpha i1 forms a complex with multiple RTKs (EGFR, PDGFR alpha, and FGFR) and the adapter protein Gab1. In vivo, the growth of subcutaneous and orthotopic glioma xenografts in nude mice was largely inhibited by expression of G alpha i1 shRNA or miRNA-200a. Collectively, miR-200a downregulation in human glioma leads to G alpha i1 over-expression, Akt activation and glioma cell proliferation.