Cdx2 modulates beta-catenin activity in intestinal cells

结肠癌是癌症死亡的重要原因。在美国，超过15万人 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。 从他们的疾病中。β-连环蛋白水平和功能的异常调节常见于 结肠癌的发生。P-连环蛋白是一种多功能蛋白，具有促进 增殖，抑制肠道细胞分化和凋亡，调节细胞间黏附， 血管生成和细胞迁移。因此，p-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。其分子机制 正常的肠道细胞调节p-连环蛋白的功能，而癌细胞通过什么来消除这一功能 监管，是不被理解的。同源结构域转录因子cdx2是一个研究得很好的 肠道特异基因表达的调节因子。其在促进肠道细胞分化和免疫调节中的作用 对增殖的调控是公认的，但其机制仍有待阐明。我们的研究 已经专门调查了这些过程。我们发现cdx2抑制p-catenin/Tcf。 转录活性。此外，癌细胞对cdx2‘S效应相对耐药。 P-连环蛋白/TCF.此外，我们还开发了一个细胞培养系统来模拟cdx2对 人结肠细胞的极化柱状细胞形态，这是一种新的机制，可归因于 Cdx2。这种作用需要一个功能性的E-钙粘蛋白/p-连环蛋白复合体，并伴随着- P-连环蛋白的翻译修饰。这项建议针对的是cdx2的特征。 介导的生物效应对细胞增殖和细胞黏附的影响，并将测试以下内容 总体假设：Cdx2抑制结肠血管增殖并促进形态 通过调节B-连环蛋白转录和细胞间黏附活性而成熟。这一假设 将通过下列相互关联的具体目标来实现：(1)研究对苯丙氨酸的抑制作用。 连环蛋白通过CDX2介导的结肠癌增殖及其对该抑制作用的抵抗 细胞；和，(2)表征CDX2介导的细胞-细胞黏附的分子机制和 柱状形态发生。因此，这项建议探索了CDX2在调节 细胞-细胞黏附的相互依赖过程，获得极化和柱状结构 形态和结肠细胞内的细胞增殖。了解这些机制将 极大地提高了我们对支配正常结肠细胞生物学的分子事件的知识，以及 同时，为散发性结肠癌的分子发病机制提供新的见解。AS 因此，潜在的新的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.