TGF-β/Smad4信号通路对结直肠癌肿瘤细胞株转移潜能影响的研究

Effect of TGF-β/Smad4 on the tumor metastasis of colorectal cancer cells

目的:探讨TGF-β/Smad4基因在结直肠癌肿瘤细胞高低转移细胞株中的表达及其作用。方法:免疫细胞化学方法检测Smad4在SW-480和SW-620细胞系中的定位,免疫印迹法检测Smad4蛋白在SW-480和SW-620细胞系中表达的差异,并构建Smad4真核表达载体,脂质体法瞬时转染Smad4基因,转染后24h应用蛋白质印迹法检测Smad4、PAI-1、VEGF和E-cad-herin的表达。结果:免疫细胞化学方法分析显示,Smad4基因在细胞核(质)表达,且Smad4在SW-480细胞中表达的平均光强度为2.356±0.431,而在SW-620细胞中表达的平均光强度为1.023±0.502,两者比较差异有统计学意义,P<0.05。蛋白质印迹法检测Smad4基因在SW-480细胞中表达高于SW-620细胞(0.675±0.356 vs0.224±0.243),瞬时转染Smad4基因24h后,转染前后PAI-1表达显著下调(4.355±0.674 vs2.110±0.524),E-cadherin表达明显上调(0.201±0.254 vs 0.899±0.325),而转染前后VEGF表达(0.867±0.359 vs 0.745±0.479)差异无统计学意义。结论:TGF-β/Smad4基因在SW-480中高表达,在SW-620中低表达,表明Smad4基因与肿瘤转移有关。TGF-β/Smad4基因通过调节PAI-1和E-cadherin的表达而抑制肿瘤转移。

OBJECTIVE： To explore the expression of TGF-13/Smad4 on high and low metastasis eolorectal cancer cell lines and its effect on tumor metastasis. METHODS： The expression of Smad4 in SW-480 and SW-620 cell lines was detected by immunohistochemistry and Western blot. Smad4 eukaryotic expression vector was constructed,Smad4 gene by liposome was transfected, and the expression of Smad4, PAI-1, VEGF,E-cadherin were detected by Western blot in 24 hours later. RESULTS： Smad4 was significant highly expressed in SW-480 （2. 356 ± 0. 431） and lowly expressed in SW-620 （1. 023±0. 502） in the cytoplasm and nucleus by immunohistochemistry （P（0. 05）, while the protein of Smad4 was also significantly higher expressed in SW-480 than that in SW-620 （0. 675~0. 356 vs O. 224~0. 243） by Western Blot. Transient transfection Smad4 gene could down regulate the expression of PAI-1 （4. 355±0. 674 vs 2. 110=t=0. 524） and up regulate the expression of E-cadherin （0. 201 ± 0. 254 vs 0. 899±0. 325）,but there was no effect on the expression of VEGF （0. 867 ± 0. 359 vs 0. 745 i 0. 479）. CONCLUSIONS： TGF-β/Smad4 is highly expressed in SW-480 and lowly expressed in SW-620, which indicates that it may be associated with tumor metastasis. And TGF-β/Smad4 can suppress tumor metastasis by regulate the expression of PAI-1 and E-cadherin.