摘要目的 研究转化生长因子β受体Ⅱ(TGFβ RⅡ)表达对微卫星不稳定(MSI)结肠癌细胞凋亡和迁移的影响.方法 选择野生型PIK3CA HCT116细胞(HCT116 wt)作为MSI结肠癌细胞模型.将TGFβRⅡ转染HCT116 wt细胞获得HCT116 wt-RⅡ细胞,并以HCT116 wt空质粒细胞作为对照.通过生长因子缺失应激(GFDS)诱导细胞凋亡.采用Western印迹检测磷酸化Smad2(TGFβ信号通路关键因子)、磷酸化AKT (PI3K/AKT信号通路关键因子)、Bim (TGFβ信号通路下游因子)和Ecadherin(诱导上皮向间质转化的标志物)表达.采用DNA碎片ELISA分析检测HCT116 wt-RⅡ细胞凋亡情况.通过Transwell实验检测HCT116 wt-RⅡ细胞迁移活力.结果 加入TGFβ后,HCT116 wt-RⅡ细胞的TGFβ信号通路得以启动,GFDS诱导的HCT116 wt-RⅡ细胞凋亡受到显著抑制(DNA碎片值:0.69±0.02比0.41±0.04,P＜0.01)；细胞迁移活力明显增强(2.10±0.15比4.03±0.48,P＜0.01).PI3K抑制剂(LY294002)可以逆转TGFβ对HCT116 wt-RⅡ细胞的凋亡抑制和迁移活力增强作用.TGFβ作用于HCT116 wt-RⅡ细胞后,Bim和E-cadherin表达明显减少.结论 TGFβRⅡ在MSI结肠癌细胞中的再表达可以增加MSI结肠癌细胞的存活能力和迁移活力,该作用依赖PI3K/AKT途径,从而为MSI结肠癌患者的良好预后提供了一个分子水平的解释.

abstractsObjective To investigate the impact of transforming growth factor-β receptor Ⅱ (TGFβ R Ⅱ ) expression on apoptosis and mobility of colon cancer cells with microsatellite instability (MSI).Methods Wild-type PIK3CA HCT116 cells (HCT116 wt) were selected as the colon cancer cell models with MSI.TGFβ3 R Ⅱ was then transfected into HCT116 wt cells so as to obtain HCT116 wt-R Ⅱ cells,with HCT116 wt pGenesil-NP cells as controls.Thereafter,apoptosis was induced by growth factor deprivation stress (GFDS).The expressions of phosphorylated Smad3,phosphorylated AKT,Bim2 and E-cadherin were detected by Western-blot,apoptosis of HCT116 wt-R Ⅱ cells by DNA fragmentation ELISA,and mobility of HCT116 wt-R Ⅱ cells by Transwell assay.Results TGFβ signaling pathways of HCT116 wt-R Ⅱ cells were started with TGFβ added (increased phosphorylated Smad2),which resulted in the significant restrain to GFDS- induced apoptosis and enhancement of cell mobility (both P＜0.01).PI3K inhibitor (LY294002) enabled to reverse the apoptosis-restricted and mobility-enhanced effects of TGFβ on HCT116 wt-R Ⅱ cells (P＜0.01).After the effects of TGFβ,the expressions of Bim and E-cadherin were significantly reduced (P＜0.01).Conclusion The re-expression of TGFβ R Ⅱ in colon cancer cells with MSI may increase the survival ability and mobility of colon cancer cells through PI3K/AKT pathway,which provides a molecular explanation for the favorable prognosis in patients with MSI colon cancer.