N-甲基-N＇-硝基-N-亚硝胍抑制细胞表皮生长因子受体酪氨酸激酶活性

目的：研究低浓度N-甲基-N′-硝基-N-亚硝胍（MNNG）诱发细胞表皮生长因子受体（EGFR）形成的二聚体,干扰了EGFR介导的下游信号转导功能的分子机制。方法：构建EGFR胞内域真核表达的载体,转染Lec-1细胞,纯化EGFR胞内域重组蛋白质后,分别以不同浓度的MNNG（0.25、0.5和1.0μmol/L MNNG）处理EGFR1h,应用酶联免疫吸附测定法检测MNNG各浓度对重组EGFR胞内域蛋白质酪氨酸激酶活性的影响。结果：MNNG浓度大于0.5μmol/L即可显著下调EGFR胞内域酪氨酸活性（P〈0.01）。结论：MNNG通过抑制EGFR胞内域的酪氨酸激酶活性而阻断其对下游信号的传递。

N-methyl-N'-nitro- N-nitrosoguanidine suppresses protein tyrosine kinase activity of epidermal growth factor receptor

OBJECTIVE:To elucidate the molecular mechanism of low concentration of N-methyl-N’-nitro-N -nitrosoguanidine(MNNG) that interfered with the function of EGFR-mediated cellular signal transduction pathway,by inducing the epidermal growth factor receptor(EGFR)clustering,which was similar to that of epidermal growth factor treatment.METHODS:Eukaryotic expression vector of EGFR cytoplasmic domain gene was constructed and transfected into Lec-1 cells.Then the recombinant EGFR cytoplasmic domain protein was purified,and treated with MNNG for 1 h,at concentrations of 0.25,0.5,and 1.0μmol/L.Enzyme linked immunoassay was used to measure the protein tyrosine kinase activity of recombinant EGFR cytoplasmic domain.Untreated recombinant cytoplasmic domain protein tyrosine kinase was used as control.RESULTS:Compared with normal control group,tyrosine kinase activity of EGFR was significantly inhibited by 0.5μmol/L MNNG(P<0.01).CONCLUSION:Low concentration of MNNG interfered with the signal transduction pathway of EGFR by supressing its tyrosine kinase activity.