Integrins and bone matrix in prostate cancer

描述（由申请人提供）：本提案集中于细胞表面粘附受体主要家族，整合素及其配体子集，骨基质蛋白之间的功能通信机制，重点是骨连接素（SPARC）和血管生成生长因子主要家族，vegf及其受体。研究这些关系的背景是前列腺癌。本研究的中心假设是整合素激活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。整合素激活的调控机制之一是通过vegf依赖的自分泌回路。骨基质配体改变VEGF/VEGFR2表达并进一步扩增VEGF自分泌环这一假设的推论也将得到验证。我们的具体目标是：目的一：整合素激活如何影响骨基质的识别？我们将引入野生型和突变形式的整合素到前列腺癌细胞中，导致静息，组成激活状态或非激活受体，并确定这些状态如何影响骨基质配体的识别。我们的研究重点将是负责前列腺癌-骨相互作用的骨蛋白，SPARC（骨连接素）。然后，我们将确定SPARC与整合素在前列腺癌细胞上相互作用的机制，这些前列腺癌细胞已知会转移到骨，相对于那些低转移潜力的前列腺癌细胞。我们将确定激活或中和V-ALIA通路是否会改变这些细胞上的整合素功能和SPARC识别。目的二世。新发现的V-ALIA通路调控回路在前列腺癌中的作用是什么？我们将评估骨基质蛋白SPARC如何影响vegf和vegfr的表达。我们将使用纯化蛋白以及正常小鼠和SPARC（-/-）小鼠的骨提取物。第三目标。V-ALIA通路在体内的作用是什么？我们将确定已经转移到骨的人类前列腺肿瘤与局限于前列腺的肿瘤的整合素激活状态。我们将比较表达非活性整合素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SPARC（-/-）小鼠骨内肿瘤的生长特征。我们努力确定前列腺肿瘤细胞对骨特异性基质蛋白的识别是如何发生的，以及调节这种识别的机制将为前列腺癌生长和转移的基本和潜在重要过程提供见解。

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.