Smad7基因过表达的促增殖作用机制探讨

Effect of overexpression of Smad7 gene on cell proliferation

目的 研究Smad7过表达使人支气管上皮细胞系增殖能力增强的机制。方法 用Smad7真核表达载体PCISmad7.neo同携带有报告基因碱性磷酸酶的c myc顺式增强子元件pMyc SEAP共转染 ,检测Smad7基因对增殖信号通路的影响。用RT PCR方法 ,检测稳定转染Smad7基因前后永生化及恶性化的人支气管上皮细胞系BEP2D和BERP35T2细胞内c myc、p15、p2 1表达水平的变化 ,调查Smad7基因对TGF β介导的抗增殖基因反应的调控。 结果 报告基因检测结果表明 ,Smad7基因可使参与增殖信号通路的c myc顺式增强子元件活性增强。RT PCR结果表明 ,在稳定转染Smad7基因的细胞中 ,c myc表达上调 ,p15表达降低 ,对TGF β刺激的应答丧失 ,p2 1表达降低。 结论Smad7基因可通过调控TGF β介导的抗增殖基因应答来影响细胞的生长。

Objective To study the effect of overexpression of Smad7 gene on cell proliferation in human bronchial epithelial cell lines. Methods Human bronchial epithelial cell lines, BEP2D and BERP35T2 cells, were cotransfected with the mammalian expression vectors PCISmad7.neo and pMyc-SEAP, the latter was a c-myc cis-acting enhancer element fused with alkaline phosphatase (SEAP) reporter gene. Expression of c-myc, p15 and p21 mRNA was detected by RT-PCR before and after stable transfection of Smad7 into BEP2D and BERP35T2 cells in order to study the regulation of TGF-beta-mediated growth inhibition. Results After BEP2D and BERP35T2 cells transfected with Smad7, the transcriptional activity of c-myc was significantly increased. Smad7 overexpressing cells showed upregulation of c-myc expression and downregulation of p15 and p21 expression, which contributed to the loss of TGF-beta responses in these cells. Conclusion Overexpression of Smad7 may facilitate cell proliferation by antagonizing TGF-β-mediated antiproliferative gene responses.