Integrins and bone matrix in prostate cancer

描述（由申请人提供）：该提案集中于细胞表面粘附受体的主要家族（整合素）及其配体的子集（骨基质蛋白）之间的功能性通信机制，重点是骨连接素（BMP）和血管生成生长因子的主要家族（VEGF及其受体）。这些关系将被检查的背景是前列腺癌。在该提议中待检验的中心假设是，整合素活化的过程优先增强骨基质配体的识别，从而选择性地增加前列腺癌细胞向骨的转移。整合素活化的调节机制之一是通过VEGF依赖的自分泌环。还将测试骨基质配体改变VEGF/VEGFR 2表达并进一步放大拟议的VEGF自分泌环这一假设的推论。我们的具体目标是：目标一。整合素活化如何影响骨基质的识别？我们将在前列腺癌细胞中引入野生型和突变形式的整合素，导致静息，组成性激活状态或不可激活的受体，并确定这些状态如何影响骨基质配体的识别。我们研究的重点将是负责前列腺癌-骨相互作用的骨蛋白，骨粘连蛋白（osteonectin）。然后，我们将确定与前列腺癌细胞上的整合素的相互作用的机制，已知转移到骨相对于那些具有低转移潜力。我们将确定V-ALIA通路的激活或中和是否会改变这些细胞上的整合素功能和整合素识别。Aim II.新发现的V-ALIA通路调节回路在前列腺癌中的作用是什么？我们将评估骨基质蛋白TGF β 1如何影响VEGF和VEGF受体的表达。我们将使用纯化的蛋白质以及来自正常小鼠和哺乳动物（-/-）小鼠的骨提取物。Aim III. V-ALIA通路在体内的作用是什么？我们将确定整合素激活状态的人前列腺肿瘤转移到骨相比，肿瘤局限于前列腺。我们将比较表达非活性和活性整合素的细胞系在骨环境中的生长特性。我们将比较WT和WT（-/-）小鼠骨内的肿瘤生长特征。我们的努力，以确定如何识别骨特异性基质蛋白的前列腺肿瘤细胞发生和什么机制调节这种识别将提供洞察到一个基本的和潜在的重要过程中操作的前列腺癌的生长和转移。

DESCRIPTION (provided by applicant): This proposal centers on the mechanisms of the functional communications between a major family of cell surface adhesion receptors, the integrins, and a subset of its ligands, the bone matrix proteins, with an emphasis on osteonectin (SPARC) and a major family of angiogenic growth factors, the VEGFs and its receptors. The context in which these relationships will be examined is prostate cancer. The central hypothesis to be tested in this proposal is that the process of integrin activation preferentially enhances recognition of bone matrix ligands, thereby selectively increasing the metastasis of prostate cancer cells to bone. One of the mechanisms of regulation of integrin activation is via VEGFdependent autocrine loop. The corollary to this hypothesis that the bone matrix ligands alter the VEGF/VEGFR2 expression and further amplify proposed VEGF autocrine loop will also be tested. Our Specific Aims are: Aim I. How does integrin activation influence recognition of the bone matrix? We will introduce wild-type and mutant forms of integrin into prostate cancer cells which result in a resting, constitutively activated state or a non-activatable receptor and determine how these states influence recognition of bone matrix ligands. The emphasis of our studies will be the bone protein that is responsible for prostate cancer - bone interactions, SPARC (osteonectin). We will then determine the mechanisms of SPARC interactions with integrins on prostate cancer cells that are known to metastasize to bone relative to those with low metastatic potential. We will determine whether activation or neutralization of the V-ALIA pathway alters integrin function and SPARC recognition on these cells. Aim II. What is the role of newly identified regulatory circuits in the V-ALIA pathway in prostate cancer? We will assess how the bone matrix protein SPARC influences the expression of VEGFs and VEGFRs. We will use purified protein as well as bone extracts from normal and SPARC (-/-) mice. Aim III. What is the role of the V-ALIA pathway in vivo? We will determine the integrin activation states of human prostate tumors that have metastasized to bone as compared to tumors localized to the prostate. We will compare the growth characteristics in bone environment of cell lines expressing inactive and active integrins. We will compare the tumor growth characteristics within the bones of WT and SPARC (-/-) mice. Our efforts to determine how the recognition of bone specific matrix proteins by prostate tumor cells occurs and what mechanisms regulate this recognition will provide insights into a basic and potentially important process operative in the growth and metastasis of prostate cancer.