蛋白酶体抑制剂MG-132对肺癌A549细胞转分化的影响

Effect of proteasome inhibitor MG-132 on epithelial mesenchymal transition of A549 cells

目的 探讨蛋白酶体抑制剂MG-132对肺癌A549细胞转分化的影响.方法 将肺癌A549细胞分为对照组（加入磷酸盐缓冲液）、T组[加入5 μg/L转化生长因子（TGF）-31]、M组（加入2.5μmol/LMG-132）、T＋M组（加入2.5 μmol/L MG-132孵育30 min后再加入5μg/L TGF-31）.倒置显微镜下观察各组培养24h后细胞形态的变化;采用免疫组织化学法检测各组细胞钙黏附蛋白E、波形蛋白、磷酸化Smad2/3蛋白及SnoN蛋白表达.结果 对照组细胞为上皮细胞所特有的铺路石样,T组细胞形态转变为梭形、纺锤形,T＋M组与M组细胞形态同对照组比较无明显差异.T组钙黏附蛋白E表达明显低于对照组、M组及T＋M组（0.144 ±0.046比0.347±0.019、0.352±0.020、0.332±0.017）;波形蛋白及磷酸化Smad2/3蛋白表达明显高于对照组、M组及T＋M组（0.483±0.063比0.130±0.034、0.134±0.015、0.166±0.011;0.367 1±0.016 9比0.073 3 ±0.000 6、0.071 3±0.000 8、0.108 5±0.002 2）;SnoN蛋白表达高于对照组和M组（0.343 7±0.013 2比0.1530±0.0027、0.161 0±0.005 7）.结论 MG-132可抑制TGF-β1诱导的A549细胞转分化,可能机制是MG-132下调磷酸化Smad2/3蛋白的表达以及上调SnoN蛋白的表达.

Objective To investigate the effect of proteasome inhibitor MG-132 on epithelial mesenchymal transition in A549 cells.Methods The A549 cells were divided into：control group added with phosphate buffer,transforming growth factorβ1 （TGF-β1）,stimulation group （T group） added with 5 μg/LTGF-β1,MG-132 group （M group） added with 2.5 μmol/L MG-132,MG-132 ± TGF-31 group （T ± M group） added with 2.5 μmol/L MG-132 followed by 5 μg/L TGF-31.The cellular morphology was observed by inverted phase-contrast microscope 24 h after treatment.Immunohistochemical technique was used to observe the expression of E-cadherin,Vimentin,p-Smad2/3 and SnoN.Results After being treated by TGF-β1 for 24 h,A549 cells in T group were found to turn to fusiform shape from pebble shape,no obvious changes were observed in T ± M group and M group compared with those in control group.The expression of E-cadherinin T group was significantly lower than that in control group,M group and T ± M group （0.144 ±0.046 vs 0.347 ±0.019,0.352 ±0.020,0.332 ±0.017）,while the express of Vimentin and p-Smad2/3 showed the opposite tendency （Vimentin：0.483 ±0.063 vs 0.130 ±0.034,0.134 ± 0.015,0.166 ± 0.011;p-Smad2/3：0.367 1 ± 0.016 9 vs 0.073 3 ± 0.000 6,0.071 3 ± 0.000 8,0.108 5 ± 0.002 2）.The expression of SnoN in T group was significantly higher than that in control group and M group （0.343 7 ±0.013 2 vs 0.153 0 ±0.002 7,0.161 0 ±0.005 7）.Conclusion MG-132 can inhibit the epithelial mesenchymal transition of A549 cells,which can be related with the cs down-regulation of p-Smad2/3 protein expression and upregulation of SnoN protein.