转化生长因子β受体Ⅱ对微卫星不稳定结肠癌细胞凋亡和迁移的影响

The impact of transforming growth factor-IS receptor lion apoptosis and mobility in colon cancer cellswith microsatellite instability

目的 研究转化生长因子β受体Ⅱ（TGFBRⅡ）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PIK3CAHCT116细胞（HCT116wt）作为MSI结肠癌细胞模型。将TGFDRⅡ转染HCTll6wt细胞获得HCTll6wt—RⅡ细胞，并以HCT116wt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（TGFD信号通路关键因子）、磷酸化AKT（P13K／AKT信号通路关键因子）、Bim（TGFB信号通路下游因子）和E-cadherin（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HCTll6wt—RⅡ细胞凋亡情况。通过Transwell实验检测HCT116wt—RⅡ细胞迁移活力。结果加入TGFB后，HCTll6wt—RlI细胞的TGFB信号通路得以启动，GFDS诱导的HCT116wt-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）。P13K抑制剂（LY294002）可以逆转TGF[3对HCTll6wt—RⅡ细胞的凋亡抑制和迁移活力增强作用。TGFβ作用于HCT116wt．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P13K／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。

Objective To investigate the impact of transforming growth factor-β receptor Ⅱ （TGFβ R Ⅱ ） expresson 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. TGFβ R Ⅱ1 was then transfected into HCTll6 wt cells so as tq obtain HCTll6 wt-R Ⅱ cells, with HCT116 wt pGenesil-NP ceils 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 Ⅱcells （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 P13K/AKT pathway, which provides a molecular explanation for the favorable prognosis in patients with MSI colon cancer.