MUCINS AND COLON CANCER PROGRESSION

描述：MUC2基因座的调节和丢失的后果 粘蛋白在结肠肿瘤发生中的作用将被研究 APC突变对杯状细胞分化和杯状细胞功能丧失的影响 粘蛋白促进遗传性肿瘤的发生。小说 将使用基因小鼠模型，在该模型中存在靶向失活的 小鼠Muc2基因和杯状细胞被特异性标记 人MUC2基因启动子连锁的β-半乳糖的表达。这个 该项目源于三个观察：(1)在人类异常隐窝病灶中 (ACF)早期癌前病变，杯状细胞枯竭， 它们产生的粘蛋白消耗殆尽。(2)基因启动的小鼠 APC 1638型，它具有APC基因的靶向失活和 概括了FAP个体的表型，也发展了ACF，作为 在人类中，表现为杯状细胞的枯竭。(3)A的表型 基因启动的小鼠(即，带有APC突变)通过以下方式减毒 COX2基因失活，提供了令人信服的证据 COX2与结肠癌的发生有关。 小鼠MUC2基因座的克隆、结构和功能分析 完成的原因有两个：指导转基因生物的建设 确定特定血统表达所需的要素(要使用 根据目标4)通过比较人类和老鼠的调节要素；以及 为Muc2缺失小鼠的研制提供试剂。因为失去了 粘蛋白是人和小鼠模型ACF形成的早期事件， MUC2-/-与APC 1638小鼠(GI)结合开发的小鼠 肿瘤的发生在ACF的发展之前)，将允许 确定粘蛋白丢失如何影响肿瘤的发展。这个 MUC2/β-Gal转基因小鼠也将能够确定 APC基因突变扰乱杯状细胞分化途径 血统；时间和早期病理损害的改变 还将定义流程。最后，研究将检验这一假设。 保护性粘蛋白的丧失(发生在ACF的早期 进展)导致炎症反应，这可能与 诱导COX2(结肠肿瘤发生的关键元件)，从而 表明粘蛋白的丢失可以促进APC启动的肿瘤。 已有的鼠标型号(APC 1638和COX2-/-)，以及 将在本提案中开发(MUC2-/-、MUC2/β-GAL)，将用于 检验这一假设。

DESCRIPTION: Regulation of the MUC2 locus and the consequences of loss of mucins in colon tumorigenesis will be investigated by pursuing the effects of an Apc mutation on goblet cell differentiation and the ability of loss of mucins to promote tumorigenesis in genetically initiated tumors. Novel genetic mouse models will be used in which there is targeted inactivation of the mouse Muc2 gene, and goblet cells are specifically labelled by the expression of beta-gal linked to the promoter of the human MUC2 gene. The project stems from three observations: (1) In human aberrant crypt foci (ACF) early preneoplastic lesions, there is depletion of goblet cells and a depletion of the mucins they produce. (2) The genetically initiated mouse model Apc 1638, which has a targeted inactivation of the Apc gene and recapitulates the phenotype of FAP individuals, also develops ACF that, as in humans, show depletion of goblet cells. (3) The phenotype of a genetically initiated mouse (i.e., with a mutation in apc) is attenuated by cyclooxygenase 2 (COX2) gene inactivation, providing compelling evidence that COX2 is involved in the development of colon cancer. The cloning, structural and functional analysis of the mouse MUC2 locus will be completed for two reasons: to guide construction of transgenics to identify the elements necessary for lineage specific expression (to be used under Aim 4) by comparison of the human and mouse regulatory elements; and to provide reagents for development of the Muc2 null mouse. Since a loss of mucins is an early event in ACF formation in human and mouse models, the Muc2-/- mouse to be developed, in combination with the Apc 1638 mouse (GI tumorigenesis is preceded by the development of ACF), will permit the determination of how mucin loss influences tumor development. The MUC2/beta-gal transgenic mice will also allow determination of whether mutation of Apc perturbs the differentiation pathway of the goblet cell lineage; alterations in the timing and early pathological lesions of this process will also be defined. Finally, studies will test the hypothesis that the loss of protective mucins (which happens in ACF, early in progression) leads to an inflammatory response that may be linked to induction of COX2 (a critical element in colon tumorigenesis), thereby demonstrating that loss of mucins can be a promoter of APC-initiated tumors. Mouse models already available (APC 1638 and COX2 -/-), as well as those to be developed in this proposal (Muc2 -/-, MUC2/beta-gal), will be used to test this hypothesis.