Molecular Analysis of CD44 on Colon Cancer Cells

简介(申请人提供)：结直肠癌是男性和女性的第三大常见癌症。一旦癌症通过血液扩散到肝脏或肺等远处器官，这种恶性肿瘤的5年存活率就会下降到8%。为了设计预防晚期疾病的新疗法，需要对结肠癌转移的分子基础有更多的了解。靶器官血行转移的关键第一步是循环癌细胞与血管内皮细胞的“拴系和滚动”附着。在剪切流条件下，E-选择素/E-选择素配体和CD44/透明质酸(HA)轴是细胞系留和滚动相互作用的主要影响因素。虽然透明质酸是CD44的主要配体，但我们实验室的研究表明，CD44的特殊糖型(称为HCELL)以高亲和力结合E-选择素。我们最近发现，人结肠癌细胞表面的CD44表达HCELL糖型，并与E-选择素和HA结合。重要的是，CD44变异体的表达和肿瘤细胞与E-选择素的结合都与结肠癌的不良预后相关。本研究旨在阐明HCELL/CD44与其配体E-选择素和HA的结合关系，以及这些黏附通路在促进肿瘤细胞从最初的捆绑/滚动到内皮细胞的迁移和组织渗透的转移级联反应中所起的作用。关于这项计划的宣布，我们试图确定癌症微环境如何影响CD44(包括糖基化导致E-选择素结合决定簇(S))的表达和功能，CD44是一种有望促进结肠癌干细胞转移的分子。这项建议的具体目的是：(1)分析CD44在结肠癌细胞上的表达水平、表面分布和功能；(2)确定微环境因素是否可以影响CD44异构体/糖体在结肠癌细胞上的表达和分布；(3)通过调控肿瘤细胞CD44的表达/功能和碳水化合物修饰，分析结肠癌细胞迁移和种植组织部位的能力。预计本文提出的研究结果将有助于更好地理解CD44在流体动力剪切条件下作为结肠癌细胞-内皮相互作用的分子效应器的作用。这些信息是设计新的治疗策略以防止结肠癌扩散的基础，因此对预防晚期疾病具有深远的意义。LAY综述：结肠癌转移的潜在分子基础尚不清楚。拟议的研究将集中在CD44上，这是一种与不良预后和疾病进展相关的分子。预计从这些研究中收集的信息将成为开发针对CD44的结肠癌治疗方法的基础。

DESCRIPTION (provided by applicant): Colorectal cancer is the third most common cancer in both men and women. The 5 year survival rate for this malignancy drops to 8% once the cancer has spread hematogenously to distant organs such as the liver or the lung. An increased understanding of the molecular basis of colon cancer metastasis is needed in order to devise novel therapies for prevention of late-stage disease. The critical first step in hematogenous metastasis of target organs is the "tethering and rolling" attachment of circulating cancer cells onto vascular endothelium. Among the principal effectors of tethering and rolling interactions of cells under shear flow conditions are E-selectin/E-selectin ligands and the CD44/hyaluronic acid (HA) axis. While HA is the principal ligand for CD44, studies from our laboratory have revealed that specialized glycoforms of CD44 (known as HCELL) bind E-selectin with high affinity. We have recently found that CD44 on human colon cancer cells express the HCELL glycoform and binds both E-selectin and HA. Importantly, expression of CD44 variants and tumor cell binding to E-selectin have each been correlated with poor prognosis in colon cancer. The studies proposed herein seek to elucidate the relationship between HCELL/CD44 binding to its ligands E-selectin and HA, and the role these adhesive pathways play in the promotion of the metastatic cascade, from the initial tethering/rolling of tumor cells on endothelium through transmigration and tissue infiltration. With respect to this Program Announcement, we seek to define how the cancer microenvironment affects expression and function of CD44 (including glycosylations rendering E-selectin binding determinant(s)), a molecule expected to promote metastasis of colon cancer "stem" cells. The Specific Aims of this proposal are: (1) To analyze the expression level, surface distribution, and function of CD44 on colon carcinoma cells; (2) To determine whether microenvironmental factors can influence expression and distribution of isoforms/glycoforms of CD44 on colon carcinoma cells; and (3) To analyze the capacity of colon carcinoma cells to transmigrate and seed tissue sites by manipulating tumor cell CD44 expression/function and carbohydrate modifications. It is anticipated that results of the studies proposed herein will lead to a greater understanding of the role of CD44 as a molecular effector of colon cancer cell-endothelial interactions under hydrodynamic shear conditions. This information is fundamental to devising new therapeutic strategies to prevent colon cancer dissemination, and thus has profound implications for prevention of late-stage disease. Lay summary: The underlying molecular basis of colon cancer metastasis is poorly understood. The proposed studies will focus on CD44, a molecule that is associated with poor prognosis and disease progression. It is anticipated that information gathered from these studies will form the basis for development of therapeutics targeting CD44 in colon cancer.