Growth Factors and Inflammatory Bowel Disease

描述（由申请方提供）：炎症性肠病（IBD）涉及肠上皮的慢性破坏以及代偿性隐窝再生和增生。在IBD期间，细胞因子和生长因子的促有丝分裂和抗凋亡作用有助于维持或恢复功能性上皮块。这些相同的机制，如果过度或延长，可能会促进发育异常和瘤形成。该提议将测试一个中心假设，即肠上皮细胞（IEC）中SOCS 3的沉默通过限制多种促肿瘤发生途径的激活来促进炎症相关的发育异常和肿瘤发生。初步数据支持一个工作模型，即IEC-SOCS 3沉默通过限制STAT、NFkB和TNF受体2（TNFR 2）的过度或异常激活来促进肿瘤发生。目的1：明确AOM/DSS诱导IEC-SOCS 3缺失小鼠肿瘤发生的细胞分子机制和基因靶点。具有IEC特异性SOCS 3破坏的小鼠在AOM/DSS后显示出增加的肿瘤数量和大小。生物化学、分子和基因微阵列研究将测试SOCS 3的缺失是否会增强STAT和NFkB及其下游遗传靶点（包括TNFR 2或新型致癌介质）的激活。目的2将定义SOCS 3对IEC或结肠癌细胞中促肿瘤发生信号传导或转录途径的直接作用，以及它们与肿瘤细胞生长或存活的相关性。表达不同水平的内源性或转基因衍生的SOCS 3或突变型SOCS 3同种型的非转化IEC-6细胞和结肠癌细胞系将用于定义SOCS 3的作用机制。将测试STAT、NFkB或TNFR 2或这些介质的特异性抑制剂的组成型激活或表达逆转SOCS 3过表达或沉默的表型或转录效应的能力。目的#3将证实IEC-SOCS 3缺失促进IBD的IL- 10无效模型中的发育异常和肿瘤发生并定义机制。将使用具有组合的IEC特异性SOCS 3破坏和IL-10基因缺失的小鼠来确认IEC-SOCS 3的缺失促进自发性小肠肿瘤和炎症相关结肠肿瘤的初步数据。生物化学和分子分析将测试在IL-10无效与AOM/DSS模型中SOCS 3是否影响相似或不同的信号传导途径和基因靶。后续研究将使用来自目标1-3的信息来设计在AOM/DSS或IL-10无效模型中使用STAT、NF：B或TNFR 2的药理学或遗传操作的实验，并定义这些介质在IEC-SOCS 3缺失的转录或肿瘤促进作用中的功能性体内作用。公共卫生相关性：患有炎症性肠病（IBD）、溃疡性结肠炎和克罗恩病的患者患结肠癌的风险增加，慢性炎症与癌症的联系越来越紧密。该项目测试了一种天然存在的身体蛋白，细胞因子信号传导抑制因子3（SOCS 3），在肠道炎症期间是否正常减少或防止结肠肿瘤的发展，以及SOCS 3是否限制了已知导致结肠癌的几种分子的作用。这些结果将指导和促进SOCS 3作为癌症风险生物标志物的使用，并协助开发基于SOCS 3的治疗方法，作为预防IBD结肠癌的新方法。

DESCRIPTION (provided by applicant): Inflammatory bowel diseases (IBD) involve chronic destruction of the intestinal epithelium, and compensatory crypt regeneration and hyperplasia. During IBD, mitogenic and anti-apoptotic effects of cytokines and growth factors help to maintain or restore functional epithelial mass. These same mechanisms, if excessive or prolonged, may promote dysplasia and neoplasia. This proposal will test a central hypothesis that silencing of SOCS3 in intestinal epithelial cells (IEC) promotes inflammation- associated dysplasia and tumorigenesis by limiting the activation of multiple pro-tumorigenic pathways. Preliminary data support a working model that IEC-SOCS3 silencing promotes tumorigenesis by limiting excessive or aberrant activation of STATs, NFkB and TNF receptor 2 (TNFR2). Aim 1 will define the cellular and molecular mechanisms and gene targets associated with enhanced AOM/DSS-induced tumorigenesis in mice with IEC-SOCS3 deletion. Mice with IEC-specific SOCS3 disruption show increased tumor number and size after AOM/DSS. Biochemical, molecular and gene microarray studies will test if loss of SOCS3 enhances activation of STAT and NFkB and their downstream genetic targets, including TNFR2, or novel oncogenic mediators. Aim 2 will define the direct effects of SOCS3 on pro-tumorigenic signaling or transcriptional pathways in IEC or colon cancer cells, and their relevance to tumor cell growth or survival. Non- transformed IEC-6 cells and colon cancer cell lines expressing different levels of endogenous or transgene derived SOCS3, or mutant SOCS3 isoforms, will be used to define mechanisms of action of SOCS3. Constitutive activation or expression of STAT, NFkB or TNFR2, or specific inhibitors of these mediators, will be tested for their ability to reverse the phenotypic or transcriptional effects of SOCS3 over-expression or silencing. Aim #3 will confirm that IEC-SOCS3 deletion promotes dysplasia and tumorigenesis in the IL- 10 null model of IBD and define mechanisms. Mice with combined IEC-specific SOCS3 disruption and IL-10 gene deletion will be used to confirm preliminary data that loss of IEC-SOCS3 promotes spontaneous small bowel tumors and inflammation-associated colon tumors. Biochemical and molecular analyses will test whether similar or distinct signaling pathways and gene targets are affected by SOCS3 in the IL-10 null versus AOM/DSS model Follow up studies will use information from aims 1-3 to design experiments using pharmacological or genetic manipulation of STAT, NF:B or TNFR2 in AOM/DSS or IL-10 null models and define the functional in vivo role of these mediators in transcriptional or tumor-promoting effects of IEC-SOCS3 deletion. PUBLIC HEALTH RELEVANCE: Patients with the inflammatory bowel diseases (IBD), ulcerative colitis and Crohn's disease have increased colon cancer risk, and chronic inflammation is increasingly linked to cancer. This project tests whether a naturally occurring body protein, suppressor of cytokine signaling 3 (SOCS3), normally reduces or prevents development of colon tumors during intestinal inflammation, and if SOCS3 limits the actions of several molecules known to cause colon cancer. The results will guide and promote use of SOCS3 as a biomarker for cancer risk and assist the development of SOCS3-based therapies as new approaches to prevent colon cancer in IBD.