Soutto Mohammed, Romero-Gallo Judith, Krishna Uma, Piazuelo M Blanca, Washington M Kay, Belkhiri Abbes, Peek Richard M, El-Rifai Wael
Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA.
Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
Oncotarget. 2015 Jul 20;6(20):17911-22. doi: 10.18632/oncotarget.3772.
Using in vitro and in vivo models, we investigated the role of TFF1 in suppressing H. pylori-mediated activation of oncogenic β-catenin in gastric tumorigenesis. A reconstitution of TFF1 expression in gastric cancer cells decreased H. pylori-induced β-catenin nuclear translocation, as compared to control (p < 0.001). These cells exhibited significantly lower β-catenin transcriptional activity, measured by pTopFlash reporter, and induction of its target genes (CCND1 and c-MYC), as compared to control. Because of the role of AKT in regulating β-catenin, we performed Western blot analysis and demonstrated that TFF1 reconstitution abrogates H. pylori-induced p-AKT (Ser473), p-β-catenin (Ser552), c-MYC, and CCND1 protein levels. For in vivo validation, we utilized the Tff1-KO gastric neoplasm mouse model. Following infection with PMSS1 H. pylori strain, we detected an increase in the nuclear staining for β-catenin and Ki-67 with a significant induction in the levels of Ccnd1 and c-Myc in the stomach of the Tff1-KO, as compared to Tff1-WT mice (p < 0.05). Only 10% of uninfected Tff1-KO mice, as opposed to one-third of H. pylori-infected Tff1-KO mice, developed invasive adenocarcinoma (p = 0.03). These findings suggest that loss of TFF1 could be a critical step in promoting the H. pylori-mediated oncogenic activation of β-catenin and gastric tumorigenesis.
我们使用体外和体内模型，研究了三叶因子1（TFF1）在抑制幽门螺杆菌介导的致癌β-连环蛋白激活从而影响胃癌发生过程中的作用。与对照组相比，胃癌细胞中TFF1表达的重建减少了幽门螺杆菌诱导的β-连环蛋白核转位（p < 0.001）。通过pTopFlash报告基因检测，这些细胞表现出显著更低的β-连环蛋白转录活性，并且与其靶基因（细胞周期蛋白D1（CCND1）和原癌基因c-MYC）的诱导水平相比，也显著更低。由于AKT在调节β-连环蛋白方面的作用，我们进行了蛋白质免疫印迹分析，并证明TFF1的重建消除了幽门螺杆菌诱导的磷酸化AKT（Ser473）、磷酸化β-连环蛋白（Ser552）、c-MYC和CCND1的蛋白水平。为了进行体内验证，我们使用了Tff1基因敲除的胃肿瘤小鼠模型。与Tff1野生型小鼠相比，在用PMSS1幽门螺杆菌菌株感染后，我们在Tff1基因敲除小鼠的胃中检测到β-连环蛋白和Ki-67的核染色增加，以及Ccnd1和c-Myc水平的显著诱导（p < 0.05）。未感染的Tff1基因敲除小鼠中只有10%发生侵袭性腺癌，而幽门螺杆菌感染的Tff1基因敲除小鼠中有三分之一发生侵袭性腺癌（p = 0.03）。这些发现表明，TFF1的缺失可能是促进幽门螺杆菌介导的β-连环蛋白致癌激活和胃癌发生的关键步骤。
