Regulation of gastric metaplasia, dysplasia and neoplasia by Bone Morphogenetic Protein signaling

慢性炎症导致胃不典型增生和肿瘤的发展。其作用机制 对这些事件负有责任的人只有部分特征。一种假设是炎症和 粘膜损伤导致胃干/祖细胞正常生物学功能异常，导致 化生和异型增生的发展，并最终发展为肿瘤。肠上皮化生(IM)和 表达化生的痉挛多肽(SPEM)与炎症诱导有关 胃肿瘤。骨形态发生蛋白(BMPs)调节细胞的生长和分化。 胃肠道组织。众所周知，BMPs还可以抑制胃炎症、细胞增殖和 胃肿瘤的生长。Lgr5基因标记了胃干细胞，它似乎扮演着重要的角色 在胃癌的发生发展中起重要作用。在胃中检测到Lgr5ve细胞的数量增加。 肿瘤。Lgr5ve细胞功能的调节机制及其在胃发育中的作用 肿瘤目前尚不清楚。在对小鼠进行的初步研究中，我们观察到Lgr5ve细胞在 胃窦腺的底部和沿着小弯，这是一个经常引起胃肿瘤的区域。 我们报道了BMP的转基因表达抑制了含氧粘膜中的BMP信号。 抑制剂noggin(H/K-nog小鼠)，增强幽门螺杆菌诱导的炎症，并诱导促进- 致癌环境，其特征是上皮细胞增殖增加和 SPEM和胃粘膜发育不良改变。我们还证明了noggin的转基因表达。 和BMP受体BMPR1A在Lgr5ve细胞中的缺失，导致Lgr5基因表达增加，并在 Lgr5ve细胞数。在诺金和费里斯同时存在的情况下进行的血统追踪研究 在Lgr5来源的细胞中证实了SPEM标志物的表达。此外，删除BMPR1A和 费氏嗜血杆菌感染导致胃不典型增生和显著的细胞变化 粘膜。本应用的总体目标是研究BMP信号在调节Lgr5中的作用 胃炎症过程中的细胞动态平衡。我们将测试炎症和抑制/丢失的假设 诱导Lgr5ve细胞的异常激活，可能导致化生和 发育不良的上皮细胞谱系，并最终导致肿瘤。为了实现这一目标，我们将进行血统追溯 利用Lgr5-Cre小鼠品系与诺金番茄报告小鼠和携带Lgr5-Cre基因的小鼠杂交的实验 BMPR1a的花序等位基因。我们还将测试细胞因子对胃的生长和分化的影响 从小鼠胃和人的活检组织中提取的有机类化合物，以定义 控制Lgr5祖细胞的动态平衡。确定骨形态发生蛋白信号在人体内的意义 对于疾病，我们将测量BMPs、干细胞标志物和BMP信号成分的表达 胃癌、胃炎和肠化生患者标本中的信号转导途径。

Chronic inflammation contributes to the development of gastric dysplasia and neoplasia. The mechanisms responsible for these events have been only partially characterized. One hypothesis is that inflammation and mucosal injury cause aberrations in the normal biological functions of gastric stem/progenitor cells leading to the development of metaplasia and dysplasia and, ultimately, to neoplasia. Both Intestinal Metaplasia (IM) and spasmolytic polypeptide expressing metaplasia (SPEM) have been associated with inflammation-induced gastric neoplasms. The bone morphogenetic proteins, (BMPs) regulate the growth and differentiation of gastrointestinal tissues. The BMPs are also known to inhibit gastric inflammation, cell proliferation and the growth of gastric neoplasms. The Lgr5 gene marks gastric stem cells and it appears to play a significant role in in the development of gastric cancer. An increased number of Lgr5+ve cells has been detected in gastric tumors. The mechanisms that regulate the function of Lgr5+ve cells and their role in the development of gastric neoplasia are currently unknown. In preliminary studies conducted in mice, we observed Lgr5+ve cells at the base of antral glands and along the lesser curvature, an area that frequently gives rise to gastric neoplasms. We reported that inhibition of BMP signaling in the oxyntic mucosa by transgenic expression of the BMP inhibitor noggin (H+/K+-Nog mice), enhances Helicobacter-induced inflammation and it induces a pro- oncogenic environment characterized by increased epithelial cell proliferation and by the development of SPEM and of dysplastic changes of the gastric mucosa. We also showed that transgenic expression of noggin and deletion of the BMP receptor BMPR1A in Lgr5+ve cells, lead to an increase in Lgr5 gene expression and in the number of Lgr5+ve cells. Lineage tracing studies conducted in the presence of both noggin and H. felis demonstrated expression of markers of SPEM in Lgr5-derived cells. Moreover, deletion of BMPR1A and infection with H. felis, caused the development of dysplasia and of significant cellular changes of the gastric mucosa. The overall goal of this application is to investigate the role of BMP signaling in the regulation of Lgr5 cell homeostasis during gastric inflammation. We will test the hypothesis that inflammation and inhibition/loss of BMP signaling induce the aberrant activation of Lgr5+ve cells that might give rise to metaplastic and dysplastic epithelial lineages, and ultimately, to neoplasias. Toward this goal we will perform lineage-tracing experiments using Lgr5-Cre mice lines crossed to both noggin-tomato reporter mice and to mice carrying floxed alleles of BMPR1A. We will also test the effects of cytokines on the growth and differentiation of gastric organoids, derived from both mice stomachs and human biopsies, in order to define the mechanisms that control the homeostasis of Lgr5 progenitors. To determine the significance of BMP signaling in human diseases, we will measure the expression of BMPs, stem cell markers and of components of the BMP signal transduction pathway in samples derived from patients with gastric cancer, gastritis and intestinal metaplasia.