Institute of Molecular Pathology and Immunology, University of Porto, Porto, Portugal.
Carcinogenesis. 2012 Oct;33(10):1985-92. doi: 10.1093/carcin/bgs233. Epub 2012 Jul 12.
Helicobacter pylori infection is the main risk factor for intestinal metaplasia (IM) and gastric cancer development. IM is a pre-neoplastic lesion, induced by the transcription factor CDX2, where the gastric mucosa is converted to an intestinal phenotype. We previously demonstrated that key elements of the bone morphogenetic protein (BMP) pathway co-localize with CDX2 in IM and upregulate CDX2 expression in gastric cell lines. These observations, together with the hypothesis that CDX2 could be repressed by SOX2, led us to test whether H. pylori, through BMPs, SOX2 and CDX2 could participate in a molecular network critical for the development of IM. AGS cells with and without SMAD4 knock-down were co-cultured with H. pylori or BMP2 to assess the expression of BMP pathway members as well as CDX2 and SOX2 by qPCR and western blot. Proximity ligation assay (PLA) was also performed to evaluate SMAD proteins interaction. Immunohistochemistry and western blot were performed in gastric samples from mice infected with Helicobacter spp. to measure Smad4, pSmad1/5/8, Cdx2 and Sox2 expression in vivo. Increased expression and activity of the BMP pathway accompanied by CDX2 upregulation and SOX2 downregulation were observed in AGS cells co-cultured with H. pylori or BMP2. These effects were impaired by downregulation of the BMP pathway. Finally, infected mice present BMP pathway upregulation, focal Cdx2 expression and decreased Sox2. These results provide a novel link between H. pylori infection and the BMP pathway in the regulation of intestinal and gastric-specific genes that might be relevant for gastric IM.
幽门螺杆菌感染是肠上皮化生（IM）和胃癌发展的主要危险因素。IM 是一种癌前病变，由转录因子 CDX2 诱导，胃黏膜转化为肠型表型。我们之前的研究表明，骨形态发生蛋白（BMP）通路的关键元件与 IM 中的 CDX2 共定位，并在上皮细胞系中上调 CDX2 的表达。这些观察结果，再加上 CDX2 可能被 SOX2 抑制的假设，使我们能够测试幽门螺杆菌是否通过 BMPs、SOX2 和 CDX2 参与 IM 发展的关键分子网络。AGS 细胞在有或没有 SMAD4 敲低的情况下与幽门螺杆菌或 BMP2 共培养，通过 qPCR 和 Western blot 评估 BMP 通路成员以及 CDX2 和 SOX2 的表达。还进行了接近连接分析（PLA）以评估 SMAD 蛋白相互作用。通过免疫组织化学和 Western blot 在感染 Helicobacter spp. 的小鼠胃组织中测量体内 Smad4、pSmad1/5/8、Cdx2 和 Sox2 的表达。在与幽门螺杆菌或 BMP2 共培养的 AGS 细胞中观察到 BMP 通路表达增加和活性增强，同时伴有 CDX2 上调和 SOX2 下调。BMP 通路的下调削弱了这些作用。最后，感染的小鼠表现出 BMP 通路的上调、焦点 Cdx2 表达和 Sox2 的减少。这些结果提供了幽门螺杆菌感染与 BMP 通路在调节肠和胃特异性基因中的新联系，这可能与胃 IM 相关。
