The Role of Integrin Affinity Modulation during Tumor Angiogenesis

整合素亲和力调节在肿瘤血管生成过程中的作用

• 批准号: 9752370
• 负责人: Fadi Emad Pulous
• 金额: $ 1.68万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-16 至 2019-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9752370
• 关键词: Ablation; Actins; Acute; Adaptor Signaling Protein; Adhesives; Affinity; Amino Acid Substitution; Angiogenic Switch; Animal Model; Automobile Driving; Basement membrane; Binding; Binding Proteins; Blood Platelets; Blood Vessels; Cancer Model; Cell Adhesion; Cell physiology; Cells; Chemosensitization; Clinical; Clinical Trials; Co-Immunoprecipitations; Complex; Conflict (Psychology); Cytoplasmic Tail; Cytoskeleton; Data; Defect; Development; Disease; Disease Progression; Disease susceptibility; Endothelial Cells; Endothelium; Exhibits; Extracellular Domain; Extracellular Matrix; Future; Genetic; Growth; Growth Factor; Hematopoietic; Hemorrhage; Impairment; In Vitro; Integrin alphaVbeta3; Integrin beta Chains; Integrin beta3; Integrins; Intercellular Junctions; Investigation; KDR gene; Knock-in; Knock-in Mouse; Laboratories; Lead; Ligand Binding; Ligands; Macromolecular Complexes; Malignant Neoplasms; Mediating; Modeling; Molecular; Molecular Conformation; Mus; Mutant Strains Mice; Neoplasm Metastasis; Neoplasms in Vascular Tissue; Pathologic Neovascularization; Pathology; Pathway interactions; Pharmacology; Phase; Play; Pre-Clinical Model; Primary Neoplasm; Process; Property; Protein Family; Publishing; Regulation; Reporting; Role; Signal Transduction; Site; Solid; Solid Neoplasm; Specificity; Structure; Talin; Tamoxifen; Testing; Tumor Angiogenesis; Vascular Endothelial Growth Factors; Work; angiogenesis; blood vessel development; design; extracellular; in vivo; inhibitor/antagonist; insight; melanoma; migration; monolayer; mouse model; mutant; neovascularization; novel; postnatal; postnatal development; pre-clinical; rapid growth; retinal angiogenesis; subcutaneous; tumor; tumor growth; tumor hypoxia; tumor microenvironment; tumor progression; tumorigenesis; tumorigenic

Project Summary: Pathological angiogenesis, the aberrant proliferation and formation of new blood vessels, during tumorigenesis culminates in an “angiogenic-switch” whereby small, avascular tumors enter a state of rapid growth driving disease progression and metastasis. Endothelial cells lining blood vessels in the tumor microenvironment respond to secreted vascular endothelial growth factor (VEGF) and navigate through the extracellular matrix (ECM) during the initial steps of sprouting angiogenesis. The integrin family of proteins modulate new vessel growth by regulating endothelial cell adhesive interactions with the ECM, neighboring endothelial cells at intercellular junctions, and with the basement membrane. Pharmacological blockade of integrins has demonstrated potent anti-tumorigenic effects in pre-clinical models, but clinical trials of this class of inhibitors have failed to show phase-III efficacy demonstrating a need for a greater understanding of integrin signaling. A noteworthy property of integrins is that their affinity for extracellular ligands is regulated through “inside-out” signaling. Talin, a cytoskeletal adaptor protein, binds the β-integrin cytoplasmic tail at two distinct sites, resulting in a conformational change whereby the extracellular domain extends into the ECM to engage ligand. We have previously published that mice expressing a platelet-specific talin1 mutant (talin1 L325R) defective in its capacity to activate integrins exhibit severe defects in platelet integrin activation that lead to a bleeding diathesis. To test the central hypothesis that talin-dependent integrin activation is required for angiogenesis (Aim #1), we have generated inducible endothelial cell-specific talin1 L325R knock-in mice (Fig 1). Induction of talin1 L325R expression during postnatal development caused early lethality and extensive defects in retinal angiogenesis (Fig 2). Interestingly, preliminary work using a B16/F10 murine melanoma model showed reductions in primary tumor size in talin1 L325R mice (Fig 3) while both talin1 L325R and talin1 WT mice exhibited no observable defects in pre-existing vasculature (Fig 5) suggesting the potential specificity of talin- dependent integrin activation for nascent vessel development. We propose to test the requirement of talin- mediated integrin activation for primary tumor growth and tumor angiogenesis. Curiously, several laboratories have reported integrin signaling promotes VEGF/VEGFR2 signaling, a central pathway responsible for angiogenesis during solid-tumor progression. Recent work suggests that stimulation of endothelial cells with VEGF induces an αvβ3-VEGFR2 macromolecular complex that potentiates VEGF signaling. In Aim 2, we will test the requirement of integrin activation during VEGF-mediated angiogenesis in vivo and whether integrin activation is necessary for downstream VEGF/VEGFR2 signal transduction. This work will provide important insight into the relationship between endothelial cell inside-out integrin signaling in angiogenesis and examine the role of talin-dependent inside-out signaling in cross-talk between integrins and VEGF signaling.

项目摘要： 病理血管生成，新血管的异常增殖和形成，在肿瘤发生期间 在“血管生成开关”中达到高潮，小血管肿瘤进入了快速生长的状态 疾病进展和转移。内皮细胞在肿瘤微环境中衬里血管 响应分泌的血管内皮生长因子（VEGF），并浏览细胞外基质 （ECM）在发芽血管生成的初始步骤中。蛋白质的整合素家族调节新容器 通过控制内皮细胞粘合剂与ECM，相邻内皮细胞的生长 细胞间连接，以及地下室膜。整联蛋白的药理封锁具有 在临床前模型中显示出有效的抗肿瘤效应，但对此类别的抑制剂进行了临床试验 未能显示出III期有效的，表明需要对整合素信号传导有更深入的了解。一个 整合素的值得注意的特性是它们对细胞外配体的亲和力通过“内而外”进行调节 信号。塔林是一种细胞骨架衔接蛋白，在两个不同的位点结合β-整合素的细胞质尾巴， 导致会议变化，细胞外域延伸到ECM以接合配体。 我们以前已经发表过，表达血小板特异性talin1突变体（Talin1 L325R）的小鼠有缺陷 它激活整联蛋白的能力在血小板整合素激活中表现出严重的缺陷，导致出血 素质。为了测试中心假设，即血管生成需要依赖塔林的整联蛋白激活 （AIM＃1），我们已经产生了诱导的内皮细胞特异性Talin1 L325R敲入小鼠（图1）。诱导 产后发育过程中Talin1 L325R表达在残留物中引起早期致死性和广泛的缺陷 血管生成（图2）。有趣的是，使用B16/F10鼠黑色素瘤模型的初步工作 Talin1 L325R小鼠中原发性肿瘤大小的减少（图3），而Talin1 L325R和Talin1 WT小鼠均减少 预先存在的脉管系统中没有明显的缺陷（图5），这表明塔林的潜在特异性 依赖性整联蛋白激活，用于新生血管发育。我们建议测试塔林的要求 介导的整联蛋白激活用于原发性肿瘤生长和肿瘤血管生成。奇怪的是，几个实验室 已经报道了整联蛋白信号传导促进VEGF/VEGFR2信号传导，这是一种负责 固体肿瘤进展过程中的血管生成。最近的工作表明，用 VEGF诱导αVβ3-VEGFR2大分子复合物，该复合物具有vegf信号的潜在。在AIM 2中，我们将 测试在VEGF介导的体内血管生成期间整联蛋白激活的需求以及整联蛋白是否 激活对于下游VEGF/VEGFR2信号传递是必需的。这项工作将提供重要的 深入了解内皮细胞内外整合素信号在血管生成中的关系并检查 talin依赖性内而外信号在整联蛋白和VEGF信号之间的串扰中的作用。