Smad4 siRNA对乳腺癌细胞侵袭力和MMP-9表达的影响

目的:探讨Smad4特异性小分子干扰RNA(siRNA)对乳腺癌MDA-MB-231细胞侵袭力及MMP-9表达的影响。方法:构建Smad4 siRNA,将细胞分为空白对照组,Smad4 siRNA转染组,TGF-β处理组,Smad4 siRNA转染+TGF-β处理组。首先用Western blot法检测转染Smad4 siRNA后细胞中Smad4蛋白的表达,以及用荧光素酶报告基因法检测TGF-β处理后细胞Smad结合元件(4xSBE)的活性;然后用Transwell小室模型和Western blot法检测各组细胞的黏附侵袭能力以及基质金属蛋白酶9(MMP-9)蛋白的表达水平。结果:转染Smad4 siRNA后,乳腺癌细胞的Smad4蛋白表达及其TGF-β诱导的4xSBE活性增强均被明显抑制(均P<0.05);与对照组细胞比较,细胞经TGF-β刺激后的侵袭能力及MMP-9的表达量均明显增加(均P<0.05),但预先转染Smad4 siRNA的细胞的上述TGF-β刺激作用被明显抑制(均P<0.05),单纯Smad4 siRNA转染对细胞的侵袭能力及MMP-9的表达量无明显影响。结论:Smad4 siRNA能减弱TGF-β诱导的MDA-MB-231细胞的侵袭能力,该作用可能与其抑制MMP-9的表达有关。

Smad4 siRNA decreases the invasive ability and MMP-9 expression of breast cancer cells

Objective:To investigate the effect of Smad4 specific small interference RNA(siRNA) on the invasive ability and MMP-9 expression of the breast cancer MDA-MB-231 cells. Methods:After Smad4 siRNA construction,the breast cancer cells were divided into control group,Smad4 siRNA transfection group,TGF-β treatment group and Smad4 siRNA transfection plus TGF-β treatment group.The expression of Smad4 protein in the breast cancer cells transfected with Smad4 siRNA was tested by Western blot analysis,and the activity of 4xSBE(Smad4 binding element) of the cells after TGF-β treatment was detected by luciferase reporter gene assay.Subsequently,the cell invasive ability and MMP-9 expression of the cells of each group were determined by using Transwell chamber system and Western blot analysis,respectively. Results:The protein expression of Smad4 and the TGF-β-induced elevation of 4xSBE activity of the breast cancer cells were significantly inhibited by Smad4 siRNA transfection(both P<0.05).The invasive ability and MPP-9 expression level of the breast cells stimulated by TGF-β were significantly increased compared with the cells of control group(both P<0.05),but these effects of TGF-β were significantly inhibited in the cells previously transfected with Smad4 siRNA(both P<0.05).The Smad4 siRNA transfection alone had no obvious effects on the invasive ability and MMP-9 expression of the cells. Conclusion:Smad4 siRNA can effectively decrease the invasive ability of MDA-MB-231 cells promoted by TGF-β1,and this effect may be associated with its inhibition of MMP-9 expression.