Cdx2 modulates beta-catenin activity in intestinal cells

结肠癌是癌症死亡的重要原因。在美国， 每年都有新的人被诊断出患有这种疾病，其中三分之一最终会死亡。 从他们的疾病。β-连环蛋白水平和功能的异常调节通常发生在 结肠癌发生β-连环蛋白是一种多功能蛋白质，已知在增强 增殖，抑制肠细胞分化和凋亡，调节细胞-细胞粘附， 血管生成和细胞迁移。因此，β-连环蛋白的失调可以赋予癌细胞 结肠癌发生所必需的许多特征。的分子机制 正常的肠细胞调节β-连环蛋白的功能，而癌细胞则通过它来消除这种功能。 规则，不被理解。同源结构域转录因子Cdx 2是一个研究得很好的转录因子。 调节子的特异性基因表达。它在促进肠细胞分化和 调节增殖是公认的，但机制仍有待阐明。我们的研究 专门研究了这些过程。我们已经发现Cdx 2抑制β-连环蛋白/TCF 转录活性此外，癌细胞对Cdx 2的作用具有相对抗性， β-连环蛋白/TCF。此外，我们已经开发了一种细胞培养系统来模拟Cdx 2诱导的细胞凋亡。 极化，柱状细胞形态在人类结肠细胞，一种新的机制， Cdx2。这种作用需要功能性的E-钙粘蛋白/β-连环蛋白复合物，以及伴随的后 β-连环蛋白的翻译修饰。该提案旨在表征Cdx 2 介导的生物学效应，并将测试以下内容 总体假设：Cdx 2抑制结肠细胞增殖并促进形态学改变 通过调节B-连环蛋白的转录和细胞-细胞粘附活性来成熟。这一假设 本研究的主要目的是：（1）研究β- 连环蛋白通过Cdx 2介导的增殖，以及结肠癌中对这种抑制作用的抗性 （2）研究Cdx 2介导的细胞间粘附的分子机制， 柱状形态发生因此，该提议探索了Cdx 2在调节细胞凋亡中的新作用。 细胞-细胞粘附的相互依赖过程，极化和柱状细胞的获得， 形态学和结肠细胞内的细胞增殖。了解这些机制将 大大提高了我们对正常结肠细胞生物学分子事件的认识， 同时，为散发性结肠癌的分子发病机制提供了新的见解。作为 因此，潜在的新型靶向治疗也可能出现。

Colon cancer is an important cause of cancer mortality. In the United States, over 150,000 people are newly diagnosed with this disease each year, and one-third of them will ultimately die from their disease. Abnormal regulation of p-catenin levels and function commonly occur during colon carcinogenesis. p-catenin is a multifunctional protein with known roles in enhancing proliferation, inhibiting intestinal cell differentiation and apoptosis, and regulating cell-cell adhesion, angiogenesis, and cell migration. Dysregulation of p-catenin can thus endow a cancer cell with many of the features necessary for colon carcinogenesis. The molecular mechanisms by which normal intestinal cells regulate p-catenin function, and by which cancer cells abrogate this regulation, are not understood. The homeodomain transcription factor Cdx2 is a well-studied regulator of intestine-specific gene expression. Its role in promoting intestinal cell differentiation and regulating proliferation is recognized but the mechanisms remain to be elucidated. Our research has specifically investigated these processes. We have found that Cdx2 inhibits p-catenin/TCF transcriptional activity. Moreover, cancer cells were relatively resistant to Cdx2's effect on p-catenin/TCF. In addition, we have developed a cell culture system to model Cdx2 induction of a polarized, columnar cell morphology in human colonocytes, a novel mechanism attributable to Cdx2. This effect requires a functional E-cadherin/p-catenin complex, and accompanying post- translational modifications of p-catenin. This proposal is directed towards characterizing Cdx2 mediated biological effects upon proliferation and cell-adhesion and will test the following overarching hypothesis: Cdx2 inhibits colonocvte proliferation and promotes morphologic maturation by modulating B-catenin transcriptional and cell-cell adhesion activity. This hypothesis will be pursued by the following inter-related Specific Aims: (1) To investigate the inhibition of p- catenin mediated proliferation by Cdx2, and the resistance to this inhibitory effect in colon cancer cells; and, (2) To characterize the molecular mechanisms for Cdx2-mediated cell-cell adhesion and columnar morphogenesis. This proposal therefore explores the novel roles for Cdx2 in regulating the interdependent processes of cell-cell adhesion, acquisition of a polarized and columnar morphology, and cell-proliferation within the colonocyte. Understanding these mechanisms will improve greatly our knowledge of the molecular events governing normal colonocyte biology, and simultaneously, provide new insights into the molecular pathogenesis of sporadic colon cancer. As a result, potential novel targeted therapeutics mayalso emerge.