Growth Factors and Inflammatory Bowel Disease

描述（由申请人提供）：炎症性肠病（IBD）涉及肠上皮的慢性破坏，代偿性隐窝再生和增生。在IBD期间，细胞因子和生长因子的有丝分裂和抗凋亡作用有助于维持或恢复功能性上皮肿块。这些相同的机制，如果过度或延长，可能促进不典型增生和瘤变。该提案将验证一个中心假设，即沉默肠上皮细胞（IEC）中的SOCS3通过限制多种促肿瘤途径的激活来促进炎症相关的异常增生和肿瘤发生。初步数据支持一个工作模型，即IEC-SOCS3沉默通过限制STATs、NFkB和TNF受体2 （TNFR2）的过度或异常激活来促进肿瘤发生。目的1将确定IEC-SOCS3缺失小鼠AOM/ dss诱导的肿瘤发生增强的细胞和分子机制以及相关的基因靶点。在AOM/DSS后，发生iec特异性SOCS3破坏的小鼠肿瘤数量和大小增加。生化、分子和基因微阵列研究将测试SOCS3的缺失是否会增强STAT和NFkB及其下游遗传靶标（包括TNFR2）或新型致癌介质的激活。目的2将确定SOCS3对IEC或结肠癌细胞中致瘤性信号通路或转录途径的直接影响，以及它们与肿瘤细胞生长或存活的相关性。未转化的IEC-6细胞和结肠癌细胞系表达不同水平的内源性或转基因衍生的SOCS3，或突变的SOCS3亚型，将用于确定SOCS3的作用机制。将测试STAT、NFkB或TNFR2的组成性激活或表达，或这些介质的特定抑制剂，以检测其逆转SOCS3过表达或沉默的表型或转录效应的能力。Aim #3将证实IEC-SOCS3缺失在IBD的IL- 10零模型中促进发育不良和肿瘤发生，并确定其机制。将使用合并了iec特异性SOCS3破坏和IL-10基因缺失的小鼠来证实初步数据，即IEC-SOCS3的丢失促进了自发性小肠肿瘤和炎症相关的结肠肿瘤。生化和分子分析将测试IL-10缺失与AOM/DSS模型中相似或不同的信号通路和基因靶点是否受到SOCS3的影响，后续研究将使用目标1-3中的信息设计实验，在AOM/DSS或IL-10缺失模型中使用STAT、NF:B或TNFR2的药理学或遗传操作，并定义这些介质在体内的功能作用，在转录或肿瘤促进作用中，IEC-SOCS3缺失。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，慢性炎症与癌症的关系越来越密切。本项目测试一种天然存在的机体蛋白，细胞因子信号传导3的抑制因子（SOCS3），是否在肠道炎症期间正常地减少或阻止结肠肿瘤的发展，以及SOCS3是否限制几种已知导致结肠癌的分子的作用。该结果将指导和促进SOCS3作为癌症风险生物标志物的使用，并协助开发基于SOCS3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.