Negative Regulation of VEGF-Mediated Angiogenesis

描述(申请人提供)：最近出现的一类抗癌疗法专注于阻止新血管的生长或血管生成，这是支持肿瘤生长所必需的。这项建议是基于一种独特的人群-唐氏综合症患者-提供的临床线索，并试图定义在唐氏综合症人群中观察到的癌症保护的分子机制。流行病学数据表明，21号染色体上存在一个3个拷贝的基因(S)，通过控制肿瘤发生的一些共同方面发挥广泛的抗癌作用。这项建议集中在这一活动的一个有希望的候选基因-唐氏综合症候选区-1(Dscr1)基因。Dscr1基因编码一种蛋白，通过负向调节血管内皮生长因子-钙调神经磷酸酶信号来阻止血管生成，特别是内皮细胞的激活。我们推测Dscr1在唐氏综合征中的三体表达通过减弱血管内皮生长因子-钙调神经磷酸酶-NFAT信号和抑制肿瘤血管生成来抑制肿瘤生长。在具体目标1中，我们将通过使用我实验室最近建立的基因工程小鼠模型来确定DSCR1的过度表达是否对唐氏综合征的肿瘤生长抑制负责。在特定的目标2中，我们将研究血栓反应蛋白-1(TSP-1)在调节肿瘤血管生成中的作用。TSP-1是我的实验室最近在内皮细胞中发现的血管内皮生长因子-钙调神经磷酸酶-NFAT信号的靶点。我们将通过血管内皮生长因子-钙调神经磷酸酶信号来确定TSP-1的调控机制，并确定其在调节血管内皮生长因子促血管生成作用中的作用。我们还将确定TSP-1缺失对内皮细胞中血管内皮生长因子信号的影响。在具体目标3中，我们将结合生化和突变方法以及小鼠移植瘤模型，确定DSCR1和药理钙调神经磷酸酶抑制剂环孢素A阻断钙调神经磷酸酶功能的不同机制。拟议的实验将利用这一临床洞察力来获得关于如何通过调节钙调神经磷酸酶的活性和功能来抑制或逆转肿瘤血管生成以及最终肿瘤生长的机械性见解。最后，这些研究还将确定Dscr1是否是抗癌干预的有效靶点。公共卫生相关性：唐氏综合症候选区-1(Dscr1)基因编码一种蛋白质，可阻止肿瘤血管生成，特别是内皮细胞的激活。DSCR1负性调节血管内皮生长因子-钙调神经磷酸酶途径，这是内皮细胞促进血管生成的重要信号途径。这些研究将确定Dscr1是否是抗癌干预的有效靶点，这可能导致抑制所有癌症的肿瘤血管生成的新的治疗策略。

DESCRIPTION (provided by applicant): A recently emerging class of anti-cancer therapies has focused on blocking the growth of new blood vessels or angiogenesis, which is necessary to support tumor growth. This proposal is based on a clinical clue provided by a unique population, individuals with Down syndrome, and seeks to define the molecular mechanisms underlying the cancer protection observed in the Down syndrome population. Epidemiological data suggests that a gene(s) present in 3 copies on chromosome 21 exerts a broad anti-cancer effect by controlling some common aspect of tumorigenesis. This proposal focuses on one promising candidate for this activity - the Down syndrome candidate region-1 (Dscr1) gene. The Dscr1 gene encodes a protein that blocks angiogenesis and specifically endothelial cell activation by negatively regulating VEGF-calcineurin signaling. We hypothesize that trisomic expression of Dscr1 in Down Syndrome suppresses tumor growth by attenuating VEGF-calcineurin-NFAT signaling and restricting tumor angiogenesis. In Specific Aim 1, we will determine whether over-expression of DSCR1 is responsible for suppression of tumor growth in Down syndrome by using genetically engineered mouse models recently generated in my lab. In Specific Aim 2 we will examine the role of thrombospondin-1 (TSP-1), a recently identified target in my lab of VEGF-calcineurin-NFAT signaling in endothelial cells, in modulating tumor angiogenesis. We will confirm the mechanism of Tsp-1 regulation by VEGF-calcineurin signaling and determine its role in modulating the pro-angiogenic effects of VEGF. We will also determine the consequences of Tsp-1 loss on VEGF signaling in endothelial cells. In Specific Aim 3, we will determine the differential mechanisms by which DSCR1 and the pharmacologic calcineurin inhibitor cyclosporin A, block calcineurin function using a combination of biochemical and mutational approaches and transplantable tumor models in mice. The experiments proposed will use this clinical insight to derive mechanistic insight into how tumor angiogenesis and ultimately tumor growth can be inhibited or reversed by modulating calcineurin activity and function. Finally these studies will also establish whether Dscr1 is a valid target for anti-cancer intervention. PUBLIC HEALTH RELEVANCE: The Down syndrome candidate region-1 (Dscr1) gene encodes a protein that blocks tumor angiogenesis and specifically endothelial cell activation. DSCR1 negatively regulates the VEGF-calcineurin pathway, an important signaling pathway in endothelial cells to promote angiogenesis. These studies will establish whether Dscr1 is a valid target for anti-cancer intervention which may lead to novel therapeutic strategies for suppressing tumor angiogenesis in all cancers.