BEP2D细胞恶性转化过程中Smad7基因对MAPK信号通路的调控  

Regulatory Effect of Smad7 Gene on MAPK Signal Pathway in Malignant Transformation of Immortalized Human Bronchial Epithelial BEP2D Cells

作　　者：王莉[1] 霍艳英[1] 张开泰[1] 王莹[1] 项晓琼[1] 胡迎春[1] 余刚[2] 李刚[1] 米粲[3] 吴德昌[1] 

机构地区：[1]军事医学科学院放射医学研究所,北京100850 [2]重庆医科大学附属第一医院神经内科,重庆400016 [3]重庆医科大学病理学教研室,重庆400016

出　　处：《癌症》2005年第9期1080-1084,共5页Chinese Journal of Cancer

基　　金：国家自然科学基金项目(No.30200329)~~

摘　　要：背景与目的:Smad7基因是转化生长因子(transforminggrouthfactor-茁,TGF-β)信号通路的抑制分子,有研究表明TGF-β通过活化SMAD通路和ras/MEK/ERK通路来诱导某些基因的表达。本研究旨在探讨在人永生化支气管上皮细胞BEP2D经辐射诱发恶性转化过程中,作为SMAD蛋白家族的抑制分子Smad7是否参与TGF-β对MAPK信号通路的调控。方法:将人工合成的Smad7siRNA及Smad7真核表达载体与pTet-Elk,pTet-Jun反式激活载体、报告基因荧光素酶共转染BEP2D细胞,TGF-β刺激,通过报告基因荧光素酶的表达丰度来检测Smad7对MAPK信号通路的调控。结果:永生化BEP2D细胞中,TGF-β刺激之后,Elk和Jun磷酸化活性升高(PElk=0.033,PJun=0.016);Elk或Jun同Smad7真核表达载体共转染之后,Elk磷酸化活性升高,Jun磷酸化活性降低(PElk=0.017,PJun=0.028);Elk或Jun同Smad7-siRNA共转染之后,Elk磷酸化活性降低,Jun磷酸化活性升高(PElk=0.018,PJun=0.005)。恶性化BERP35T2细胞中,TGF-β刺激之后,Elk磷酸化活性增强(P=0.006),Elk同Smad7siRNA共转染之后,Elk磷酸化活性降低(P=0.000);恶性化细胞中几乎检测不到Jun的活性。结论:在BEP2D细胞发生恶性转化过程中,Smad7基因干预MAPK信号通路,使ERK和JNK磷酸化活性的平衡失调,导致促增殖作用强于生长抑制作用,从而有助于细胞向恶性方向发展。BACKGROUND ＆ OBJECTIVE. Smad7 is an inhibitor of transforming growth factor-β （TGF-β） signal pathway. TGF-β could induce the expression of several genes through activating SMAD and ras/MEK/ERK pathways, This study was to determine whether Smad7 is involved in regulating mitogen-activated protein kinase （MAPK） signal pathway with TGF-β in malignant transformation of human METHODS： Immortalized BEP2D cel colls and malignant BERP35T2 cells were co-transfected with full-length Smad7 cDNA constructed pCISmad7.neo or Smad7 siRNA, transactivator vector pTet-EIk or pTet-Jun, and reporter vector pTRE-Luc, and stimulated with TGF-β. The regulatory effect of Smad7 on MAPK signal pathway was investigated by standard luciferase assay. RESULTS： In BEP2D cells, when treated with TGF-β1, phosphorylated activities of Elk and Jun were up-regulated （PEIk=0.033, PJun=0.016）; after co-transfection of Elk or Jun with pCISmad7.neo, phosphorylated activity of Elk was increased, and that of Jun was decreased （PEIk=0.017, PJun=0.028） ; after co-transfection of EIk or Jun with Smad7 siRNA, phosphorylated activity of Elk was decreased, and that of Jun was increased （PEIk=0.018, PJun= 0.005）. In BERP35T2 cells, when treated with TGF-β1, phosphorylated activity of Elk was up-regulated （P=0.006）; after co-transfection of Elk and Smad7 siRNA, phosphorylated activity of Elk was decreased （P=0.000）; no activity of Jun was detected in BERP35T2 cells. CONCLUSIONS： In the process of malignant transformation of BEP2D cells, the intervention of Smad7 in MAPK signal pathway leads to the activity imbalance between extracellular signal-related protein kinase （ERK） and c-Jun NH2-terminal kinase （JNK）, which in turn promotes cell proliferation. All these could contribute to further malignant transformation of these cells.

关 键 词：BEP2D细胞 SMAD7 TGF-β MAPK 信号通路 细胞恶变/辐射效应 

分 类 号：R73-3[医药卫生—肿瘤]