TGFBR1 Signaling in Colorectal Cancer

结直肠癌中的 TGFBR1 信号转导

基本信息

批准号：
8006404
负责人：
Boris Pasche
金额：
$ 30.63万
依托单位：
UNIVERSITY OF ALABAMA AT BIRMINGHAM
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-01-01 至 2014-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8006404
关键词：
9q22 Address Adenocarcinoma Alleles Azoxymethane Breeding Cell Proliferation Cells Chemopreventive Agent Colon Carcinoma Colonic Neoplasms Colorectal Cancer Data Development Embryo Epithelial Cell Proliferation Epithelium Exhibits Fibroblasts Future Gastrointestinal tract structure Gene Expression Genes Genetic Goals Growth Human In Vitro Individual Inherited Intestinal Mucosa Intestinal Neoplasms Intestines Link Loss of Heterozygosity Lymphoid Cell MADH2 gene MADH3 gene MADH4 gene Malignant Neoplasms Maps Mediating Modeling Molecular Mus Mutation Nude Mice Oncogenic Pathogenesis Pathology Patients Phenotype Phosphorylation Phosphorylation Inhibition Positioning Attribute Predisposition Property Protocols documentation Public Health Receptor Gene Reporting Research Personnel Role Science Seminal Signal Transduction Stem Cell Development Stem cells TGFBR1 gene Testing Therapeutic Agents Time Transgenic Organisms Tumor Stem Cells Tumor Suppressor Genes Tumor Suppressor Proteins Variant cancer prevention cancer risk cancer stem cell cancer therapy in vivo innovation mouse model novel null mutation peripheral blood public health relevance receptor research study tumor tumorigenesis

项目摘要

DESCRIPTION (provided by applicant): We generated a novel model of mice heterozygous for a targeted null mutation of Tgfbr1. When crossed with mice carrying a mutation in the Apc tumor suppressor gene, these mice develop twice as many intestinal tumors as wild-type littermates. Invasive adenocarcinoma with features of human colon cancer is only identified among ApcMin/+; Tgfbr1+/- mice, not among ApcMin/+; Tgfbr1+/+ mice and tumors do not exhibit loss of heterozygosity at the Tgfbr1 locus. TGF-?-mediated growth inhibition, phosphorylation of Smad2 and Smad3, and overall TGF-? signaling are mildly decreased in haploinsufficient embryonic fibroblasts. Decreased Smad2 and Smad3 phosphorylation is observed in the colonic epithelium crypts of ApcMin/+; Tgfbr1+/- mice. Decreased Smad signaling is associated with increased cell proliferation in the crypts of the intestinal mucosa and intestinal tumors. Thus, constitutively reduced Tgfbr1-mediated signaling is a potent modifier of colorectal cancer development. To determine the relevance of these findings in humans, we analyzed germline peripheral blood for TGFBR1 expression. We found that 29 of 242 (12.0%) patients with colorectal cancer but only three of 195 (1.5%) controls had evidence of germline allele-specific expression of TGFBR1 (TGFBR1 ASE). These results indicate that TGFR1 ASE is one of the most commonly inherited cause of colorectal cancer, which increases cancer risk by approximately 870%. Differences in TGF-?-mediated phosphorylation of SMAD2 and SMAD3 between human lymphoid cells from individuals with wild-type TGFBR1 and individuals with TGFBR1 ASE were comparable to those found between Tgbr1+/+ and Tgfbr1+/- mouse embryonic fibroblasts. It is the purpose of the studies outlined in this application to unravel the molecular mechanisms of Tgfbr1 haploinsufficiency in colorectal cancer through execution of three Specific Aims: First: To characterize the phenotype of Tgfbr1+/+ and Tgfbr1+/- mice with respect to colon cancer: The phenotype of Tgfbr1+/+ and Tgfbr1+/- mice will be evaluated in three different backgrounds (129Sv/J, C57BL/6 and FVB/N). Colon tumors will be induced using the azoxymethane protocol and by crossing the transgenic strains with Apc1638N/+ and KRASV12G; Apc1638N/+ mice. Second: To determine the role of Tgfbr1 haploinsufficiency in development of cancer stem cells and intestinal stem cells as well as the contribution of stromal and lymphoepithelial Tgfbr1 signaling to tumor formation: We will determine the growth of Tgfbr1+/+ and Tgfbr1+/- tumors in nude mice to evaluate the contribution of Tgfbr1 haploinsufficiency on tumor stem cell development. Using the Lgr5 mouse model, we will also assess whether Tgfbr1 haploinsufficiency enhances the development of intestinal stem cells. The role of Tgfbr1 haploinsufficiency within stromal and lymphoepithelial cells will be evaluated as it relates to colon cancer development. Third: To assess Tgfbr1 haploinsufficiency oncogenic properties: Using MEFs from three distinct genetic backgrounds (129Sv/J, C57BL/6 and FVB/N) we will determine the extent to which Tgfbr1 haploinsufficiency enhances oncogenesis. PUBLIC HEALTH RELEVANCE: We have shown that decreased expression of the type I TGF-? receptor gene is emerging as the most common cause of colorectal cancer reported to date. The primary goal of this project is to understand the mechanisms linking decreased gene expression and colorectal cancer development. Experiments will be conducted with mice that only express one copy of the gene, which will be bred together with mice that spontaneously develop colon cancer.

描述（由申请人提供）：我们生成了一种新的 Tgfbr1 目标无效突变杂合小鼠模型。当与携带 Apc 肿瘤抑制基因突变的小鼠杂交时，这些小鼠产生的肠道肿瘤数量是野生型同窝小鼠的两倍。仅在 ApcMin/+ 中发现具有人类结肠癌特征的侵袭性腺癌； Tgfbr1+/- 小鼠，不在 ApcMin/+ 中； Tgfbr1+/+ 小鼠和肿瘤在 Tgfbr1 基因座上没有表现出杂合性丢失。 TGF-β介导的生长抑制、Smad2和Smad3的磷酸化以及总体TGF-β单倍体不足的胚胎成纤维细胞中的信号传导轻度减少。在 ApcMin/+ 的结肠上皮隐窝中观察到 Smad2 和 Smad3 磷酸化减少； Tgfbr1+/- 小鼠。 Smad 信号传导减少与肠粘膜隐窝和肠肿瘤中细胞增殖增加有关。因此，组成性减少的 Tgfbr1 介导的信号传导是结直肠癌发展的有效调节剂。为了确定这些发现在人类中的相关性，我们分析了种系外周血中 TGFBR1 的表达。我们发现 242 名结直肠癌患者中有 29 名 (12.0%) 具有 TGFBR1 (TGFBR1 ASE) 种系等位基因特异性表达的证据，但 195 名对照中只有 3 名 (1.5%) 有证据。这些结果表明 TGFR1 ASE 是结直肠癌最常见的遗传原因之一，它使癌症风险增加约 870%。来自野生型 TGFBR1 个体和 TGFBR1 ASE 个体的人淋巴细胞之间 TGF-β 介导的 SMAD2 和 SMAD3 磷酸化差异与 Tgbr1+/+ 和 Tgfbr1+/- 小鼠胚胎成纤维细胞之间发现的差异相当。本申请中概述的研究的目的是通过执行三个具体目标来揭示结直肠癌中 Tgfbr1 单倍体不足的分子机制：第一：表征 Tgfbr1+/+ 和 Tgfbr1+/- 小鼠相对于结肠癌的表型： Tgfbr1+/+ 和 Tgfbr1+/- 小鼠的表型将在三种不同的背景（129Sv/J、 C57BL/6 和 FVB/N）。将使用氧化偶氮方案并将转基因菌株与 Apc1638N/+ 和 KRASV12G 杂交来诱导结肠肿瘤； Apc1638N/+ 小鼠。第二：确定Tgfbr1单倍体不足在癌症干细胞和肠道干细胞发育中的作用以及基质和淋巴上皮Tgfbr1信号传导对肿瘤形成的贡献：我们将确定裸体内Tgfbr1+/+和Tgfbr1+/-肿瘤的生长小鼠评估 Tgfbr1 单倍体不足对肿瘤干细胞发育的贡献。使用 Lgr5 小鼠模型，我们还将评估 Tgfbr1 单倍体不足是否会增强肠道干细胞的发育。将评估基质细胞和淋巴上皮细胞中 Tgfbr1 单倍体不足的作用，因为它与结肠癌的发展有关。第三：评估 Tgfbr1 单倍剂量不足的致癌特性：使用来自三个不同遗传背景（129Sv/J、C57BL/6 和 FVB/N）的 MEF，我们将确定 Tgfbr1 单倍剂量不足增强肿瘤发生的程度。公共健康相关性：我们已经证明，I 型 TGF-β 的表达下降。受体基因正在成为迄今为止报道的结直肠癌最常见的原因。该项目的主要目标是了解基因表达减少与结直肠癌发展之间的联系机制。实验将用只表达该基因一份拷贝的小鼠进行，这些小鼠将与自发患结肠癌的小鼠一起繁殖。