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常见的癌症。 一旦癌症通过血液扩散到远处器官，如肝脏或肺，这种恶性肿瘤的5年生存率下降到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理解。 靶器官的血行转移的关键第一步是循环癌细胞在血管内皮上的“束缚和滚动”附着。 在剪切流条件下细胞的束缚和滚动相互作用的主要效应物中有E-选择素/E-选择素配体和CD 44/透明质酸（HA）轴。 虽然HA是CD 44的主要配体，但我们实验室的研究表明，CD 44的特化糖型（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上的CD 44表达HCELL糖型并结合E-选择素和HA。 重要的是，CD 44变体的表达和与E-选择素结合的肿瘤细胞各自与结肠癌的不良预后相关。 本文提出的研究试图阐明HCELL/CD 44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中的作用，从肿瘤细胞在内皮上的初始束缚/滚动到迁移和组织浸润。 关于这个计划公告，我们试图确定癌症微环境如何影响CD 44的表达和功能（包括糖基化，使E-选择素结合决定簇），一种预期促进结肠癌“干”细胞转移的分子。 本研究的具体目的是：（1）分析结肠癌细胞表面CD 44的表达水平、表面分布和功能，（2）确定微环境因素是否影响结肠癌细胞表面CD 44的表达和分布;（3）通过调控肿瘤细胞CD 44的表达/功能和碳水化合物的修饰来分析结肠癌细胞迁移和接种组织部位的能力。 预计本文提出的研究结果将导致更好地理解CD 44作为流体动力学剪切条件下结肠癌细胞-内皮相互作用的分子效应物的作用。 这些信息对于设计新的治疗策略以预防结肠癌扩散是至关重要的，因此对预防晚期疾病具有深远的意义。 概述：结肠癌转移的潜在分子基础知之甚少。 拟议的研究将集中在CD 44上，这是一种与预后不良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结肠癌中靶向CD 44的治疗剂的基础。

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.