Molecular Analysis of CD44 on Colon Cancer Cells

描述（由申请人提供）：结直肠癌是男性和女性中第三大常见癌症。这种恶性肿瘤的5年生存率一旦血液扩散到远处器官，如肝或肺，就会下降到8%。为了设计预防晚期疾病的新疗法，需要增加对结肠癌转移的分子基础的了解。靶器官血液转移的关键第一步是循环癌细胞在血管内皮上的“捆绑和滚动”附着。在剪切流动条件下，细胞的捆绑和滚动相互作用的主要影响因素是e -选择素/ e -选择素配体和CD44/透明质酸（HA）轴。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）与e -选择素具有高亲和力。我们最近发现CD44在人结肠癌细胞上表达HCELL糖型并结合e -选择素和HA。重要的是，CD44变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。本文提出的研究旨在阐明HCELL/CD44与其配体e -选择素和HA结合之间的关系，以及这些粘附途径在促进转移级联反应中所起的作用，从肿瘤细胞在内皮细胞上的初始栓系/滚动到转移和组织浸润。关于本项目公告，我们试图定义癌症微环境如何影响CD44的表达和功能（包括糖基化产生e -选择素结合决定因子），这是一种有望促进结肠癌“干细胞”转移的分子。本课题的具体目的是：(1)分析CD44在结肠癌细胞中的表达水平、表面分布和功能；(2)确定微环境因素是否会影响CD44亚型/糖型在结肠癌细胞中的表达和分布；(3)通过调控肿瘤细胞CD44表达/功能和碳水化合物修饰，分析结肠癌细胞迁移和种子组织部位的能力。预计本文提出的研究结果将导致对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的作用有更深入的了解。这一信息对于制定预防结肠癌传播的新治疗策略至关重要，因此对预防晚期疾病具有深远的意义。总结：结肠癌转移的潜在分子基础尚不清楚。拟议的研究将集中于CD44，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为开发靶向CD44的结肠癌治疗方法奠定基础。

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.