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目的:研究慢性高胰岛素对胰岛素受体后信号转导的影响及其与胰岛素抵抗的关系,并探讨二甲双胍治疗胰岛素抵抗是否通过胰岛素信号转导途径的介导。方法:人类肝癌细胞系(Hep G2)在无血清条件下首先与100nmol/L高浓度胰岛素预温育16h以产生胰岛素抵抗细胞模型,并观察不同浓度(0.01-10mmol/L)的二甲双胍对胰岛素受体后磷酯酰肌醇3激酶(PI3K)途径信号转导的影响。结果:高浓度胰岛素100nmol/L慢性处理引起了IRβ、IRS1和IRS2的酪氨酸磷酸化和蛋白表达水平的下调,p85与IRS的相互作用也有显著降低。生理治疗浓度的(0.01-0.1mmol/L)二甲双胍逆转了这种慢性高胰岛素引起的信号下调,细胞用0.1mmol/L二甲双胍预温育后,IRB、IRS1和IRS2的磷酸化反应水平分别增加了2.7倍(P<0.01),6.8倍(P<0.01)和2.3倍(P<0.01),p85与IRS1的相互作用从34％增加至86％(P<0.01),与IRS2的相互作用从30％增加至92％(P<0.01)。相反,药物浓度(1-10mmol/L)的二甲双胍进一步抑制了IRB、IRS的磷酸化及IRS与p85的相互作用。结论:高浓度胰岛素慢性处理可引起胰岛素受体后PI3K途径信号转导的下调,二甲双胍对胰岛素信号转导的作用可能是其治疗胰岛素抵抗的主要分子机制。
OBJECTIVE: To study the effect of chronic hyperinsulinism on signal transduction of insulin receptor and its relationship with insulin resistance and to explore whether metformin treatment of insulin resistance is mediated by insulin signaling pathway. Methods: Human hepatoma cell line (Hep G2) was preincubated with high concentration insulin (100nmol / L) for 16h under serum-free condition to generate insulin resistance cell model. The effects of metformin at different concentrations (0.01-10mmol / L) Effect of Post-phosphatidylinositol 3-kinase (PI3K) Pathway Signal Transduction. Results: Chronic treatment with 100 nmol / L of high concentration of insulin caused the down-regulation of tyrosine phosphorylation and protein expression of IRβ, IRS1 and IRS2, and the interaction between p85 and IRS was also significantly reduced. Physiotherapeutic concentrations (0.01-0.1 mmol / L) metformin reversed this chronic hyperinsulin-induced signal downregulation, and the phosphorylation levels of IRB, IRS1 and IRS2 increased after cells were preincubated with 0.1 mmol / L metformin (P <0.01), 6.8 times (P <0.01) and 2.3 times (P <0.01) respectively. The interaction between p85 and IRS1 increased from 34% to 86% (P <0.01) % To 92% (P <0.01). In contrast, metformin at drug concentrations (1-10 mmol / L) further inhibited IRB, phosphorylation of IRS and IRS interaction with p85. CONCLUSION: Chronic treatment with high concentration of insulin can cause the down-regulation of PI3K signaling pathway after insulin receptor. The effect of metformin on insulin signaling may be the main molecular mechanism of insulin resistance.