Cryptic Domains of Collagen-IV in Tumor Growth

描述（由申请人提供）：我们将验证细胞与隐性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。这一建议的目的是基于两种新型试剂的实验，这些试剂选择性地结合胶原蛋白iv中的隐表位。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着重要作用。然而，人们对这些隐性ECM表位的作用机制知之甚少。我们的研究已经确定了HUIV26的隐表位，它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，细胞与变性胶原- iv的相互作用可以被avb3或Mab HUIV26拮抗剂部分抑制。b1整合素拮抗剂也可以部分抑制相互作用，而avb3和b1拮抗剂的组合完全抑制细胞与变性胶原- iv的相互作用。这些观察结果表明，在变性胶原- iv中，除了HUIV26隐藏位点外，至少还有一个其他隐藏表位暴露。我们的新研究表明，由合成肽识别的第二个隐性表位暴露在变性胶原- iv中。阻断与第二隐表位的相互作用可能抑制粘附、迁移和增殖。综上所述，我们的研究表明，iv型胶原蛋白中存在至少两个不同的被不同整合素受体识别的隐性表位，这些表位可能代表了恶性肿瘤治疗的新靶点。基于我们的发现，这些研究旨在检验四个中心目标。首先，我们将确定HUIV26隐表位的氨基酸序列，并研究该表位调控TSP-1的潜在机制。其次，我们将确定与第二个隐表位相互作用对体外侵袭性细胞行为的功能后果，鉴定第二个隐表位的受体，并研究与该表位相互作用调节细胞行为的机制。第三，我们将确定隐性表位的可溶性形式是否在循环中释放，以及这些可溶性形式是否与肿瘤进展相关。最后，我们将确定第二个隐性表位是否在体内血管生成、肿瘤生长和转移中发挥作用。这些研究可能会导致人类肿瘤治疗新策略的发展。

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.