Molecular Dissection of the Angiogenic Response Induced by VEGF-A

为了超过最小尺寸，肿瘤必须生成新的血管。MOST表达的血管内皮生长因子-A 恶性肿瘤是肿瘤血管生成的主要原因，在 激活钙级联、诱导血管高通透性的血管生成因子。 高通透性是新形成的肿瘤血管的一个特征，具有重要的作用 N肿瘤血管生成和间质形成。分泌血管内皮生长因子-A的肿瘤诱导的新生血管 至少有6种不同的类型，使用一种能够表达血管内皮生长因子-A164的腺病毒载体，我们有 能够在各种正常的小鼠组织中产生每种血管类型的代理形式。中的 几种类型的肿瘤血管，母血管(MV)是最先形成的，也是主要的 高渗透血管亚群。过度表达VEGFR-1的MV是极大的周细胞贫乏的血窦。 和-2；它们也是许多快速生长的小鼠肿瘤中发现的最常见的血管类型，以及 在人类肿瘤中也很常见。我们发现，血管内皮生长因子-A的大部分血管生成活性是 通过孤儿核转录因子TR3(人)/Nur77(小鼠)介导。我们的整体 假说认为，TR3/Nur77在调节血管内皮生长因子-A诱导的血管生成中起着中心的、基本的作用 通透性、血管超微结构和导致肿瘤血管生成的最早时相 高渗透性的母体血管。两个具体的目标将检验这一中心假设：目标1.量化 Nur77表达水平对血管通透性、血管超微结构和血管生成的影响 利用野生型和工程化NUR77-/-和转基因NUR77-S小鼠，目的2.阐明NUR77-/-转基因小鼠 激活钙离子并调节TR3表达和转录活性的信号通路 培养内皮细胞，在体内进行Matrigel Plug试验。这些目标使用了不同的技术 专注于一个目标，阐明血管内皮生长因子-A诱导TR3/Nur77的步骤和机制 表达和激活等血管生成和相关的血管高通透性。 与公众健康相关：这些研究将阐明肿瘤形成的机制 他们生长和生存所需的新血管，并在这个过程中识别新的潜力 肿瘤血管攻击的靶点和干预要点。

To grow beyond minimal size, tumors must generate new blood vessels. VEGF-A, expressed by most malignant tumors is primarily responsible for tumor angiogenesis and has the unusual property among angiogenic factors of activating the Ca2+ cascade and inducing vascular hyperpermeability. Hyperpermeability is a characteristic feature of newly formed tumor blood vessels and has an important role n tumor angiogenesis and stroma formation. The new blood vessels induced by VEGF-A-secreting tumors are of at least 6 distinct types and, using an adenoviral vector engineered to express VEGF-A164, we have been able to generate surrogate forms of each vessel type in a variety of normal mouse tissues. Of the several types of tumor blood vessels, mother vessels (MV) are the first to form and are the primary hyperpermeable vessel subset. MV are greatly enlarged, pericyte-poor sinusoids that overexpress VEGFR-1 and -2; they are also the commonest type of blood vessel found in many rapidly growing mouse tumors, and are also common in human tumors. We have found that much of VEGF-A's angiogenic activities are mediated through an orphan nuclear transcription factor, TR3 (human)/Nur77 (mouse). Our overall hypothesis is that TR3/Nur77 has a central, essential role in regulating VEGF-A-induced vascular permeability, vascular ultrastructure and the earliest phase of tumor angiogenesis that leads to the formation of hyperpermeable mother vessels. Two Specific Aims will test this central hypothesis: Aim 1. Quantify the effects of Nur77 expression levels on vascular permeability, vascular ultrastructure and angiogenesis, making use of wild type and engineered Nur77-/- and transgenic Nur77-S mice, and Aim 2. Elucidate the signaling pathways that activate Ca2+ and that regulate TR3 expression and transcriptional activity in cultured endothelial cells and in Matrigel plug assays in vivo. These Aims make use of different technologies to focus on a single objective, elucidating the steps and mechanisms by which VEGF-A induces TR3/Nur77 expression and activation, and so angiogenesis and associated vascular hyperpermeability. Relevance to public health: These studies will clarify the mechanisms by which tumors initiate the formation of the new blood vessels they require for growth and survival and, in the process, identify new potentia targets and points of intervention for attacking the tumor vasculature.