Cryptic Domains of Collagen-IV in Tumor Growth

描述（由申请人提供）：我们将检验细胞与隐蔽胶原表位的相互作用在调节肿瘤生长和血管生成中发挥独特作用的假设。该建议的目的是基于两种新型试剂的实验，所述试剂选择性结合IV型胶原内的隐蔽表位。细胞外基质（ECM）的蛋白水解重构在血管生成和肿瘤生长中起重要作用。然而，关于这些隐蔽ECM表位发挥作用的机制知之甚少。我们的研究已经鉴定了HUIV 26隐蔽表位，其在体外调节内皮细胞和肿瘤细胞的粘附和迁移，在体内调节血管生成和肿瘤生长。有趣的是，与变性胶原-IV的细胞相互作用可以被avb 3或Mab HUIV 26的拮抗剂部分抑制。b1整联蛋白的拮抗剂也可以部分抑制相互作用，而avb 3和b1拮抗剂的组合完全抑制与变性胶原-IV的细胞相互作用。这些观察结果表明，除了HUIV 26隐蔽位点之外，至少一个其他隐蔽表位暴露在变性胶原-IV内。我们的新研究表明，由合成肽识别的第二个隐蔽表位暴露在变性的IV型胶原蛋白中。阻断与该第二隐蔽表位的相互作用可以抑制粘附、迁移和增殖。两者合计，我们的研究表明，至少有两个不同的隐蔽表位识别不同的整合素受体存在于IV型胶原蛋白，这些表位可能代表新的治疗恶性肿瘤的治疗靶点。根据我们的研究结果，这些研究旨在检查四个中心目标。首先，我们将定义HUIV 26隐蔽表位的氨基酸序列，并研究该表位调节TSP-1的潜在机制。其次，我们将确定与第二个隐蔽表位的相互作用对体外侵入性细胞行为的功能后果，并确定第二个隐蔽表位的受体，并研究与该表位的相互作用调节细胞行为的机制。最后，我们将确定第二个隐藏表位是否在体内血管生成、肿瘤生长和转移中起作用。这些研究可能会导致治疗人类肿瘤的新策略的开发。

DESCRIPTION (provided by applicant): We will test the hypothesis that cellular interaction with cryptic collagen epitopes play unique roles in regulating tumor growth and angiogenesis. The aims of this proposal are based on experiments with two novel reagents that selectively bind cryptic epitopes within collagen-IV. Proteolytic remodeling of the extracellular matrix (ECM) plays important roles in angiogenesis and tumor growth. However, little is known concerning the mechanisms by which these cryptic ECM epitopes function. Our studies have identified the HUIV26 cryptic epitope that regulates endothelial and tumor cell adhesion and migration in vitro and angiogenesis and tumor growth in vivo. Interestingly, cellular interactions with denatured collagen-IV can be partially inhibited by antagonists of avb3 or Mab HUIV26. Antagonists of b1 integrins can also partially inhibit interactions while a combination of both avb3 and b1 antagonists completely inhibit cellular interactions with denatured collagen-IV. These observations suggest that at least one other cryptic epitope, in addition to the HUIV26 cryptic site is exposed within denatured collagen-IV. Our new studies suggest that a second cryptic epitope recognized by a synthetic peptide is exposed within the denatured collagen-IV. Blocking interactions with this second cryptic epitope may inhibit adhesion, migration and proliferation. Taken together, our studies suggest that at least two distinct cryptic epitopes recognized by different integrin receptors are present within collagen type-IV and that these epitopes may represent novel therapeutic targets for the treatment of malignant tumors. Based on our findings, the studies were designed to examine four central objectives. First, we will define the amino acid sequence of the HUIV26 cryptic epitope and examine potential mechanisms by which this epitope regulates TSP-1. Second, we will determine the functional consequences of interactions with the second cryptic epitope have on invasive cellular behavior in vitro and identify receptors for the second cryptic epitope and examine mechanisms by which interactions with this epitope regulates cellular behavior. Third, we will determine whether soluble forms of the cryptic epitope are released in the circulation and whether these soluble forms correlate with tumor progression Finally, we will determine whether the second cryptic epitope plays a role in angiogenesis, tumor growth and metastasis in vivo. These studies may result in the development of novel strategies for the treatment of human tumors.