Cryptic Domains of Collagen-IV in Tumor Growth

描述(申请人提供)：我们将测试这样一个假设，即细胞与隐蔽的胶原表位的相互作用在调节肿瘤生长和血管生成方面发挥着独特的作用。这项建议的目的是基于两种新型试剂的实验，这两种试剂选择性地结合IV型胶原蛋白中的隐蔽表位。细胞外基质(ECM)的蛋白水解性重塑在血管生成和肿瘤生长中起重要作用。然而，关于这些隐秘的ECM表位的作用机制，人们知之甚少。我们的研究已经确定了HUIV26隐蔽表位，它在体外调节血管内皮细胞和肿瘤细胞的黏附和迁移，在体内调节血管生成和肿瘤生长。有趣的是，细胞与变性的IV型胶原的相互作用可以被avb3或Mab HUIV26的拮抗剂部分抑制。B1整合素的拮抗剂也可以部分抑制相互作用，而avb3和b1拮抗剂的组合则完全抑制细胞与变性的IV型胶原的相互作用。这些观察表明，在变性的IV型胶原中，除了HUIV26隐蔽位点外，至少还有另一个隐蔽表位。我们的新研究表明，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。阻断与第二个隐蔽表位的相互作用可能会抑制黏附、迁移和增殖。综上所述，我们的研究表明，在IV型胶原中至少存在两个由不同整合素受体识别的不同的隐蔽表位，这些表位可能是治疗恶性肿瘤的新靶点。根据我们的发现，这些研究旨在检查四个核心目标。首先，我们将定义HUIV26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相互作用对体外侵袭细胞行为的功能后果，并确定第二个隐蔽表位的受体，并研究与该表位相互作用调节细胞行为的机制。最后，我们将确定第二个隐含表位是否在体内血管生成、肿瘤生长和转移中发挥作用。这些研究可能导致开发治疗人类肿瘤的新策略。

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.