Molecular Dissection of the Angiogenic Response Induced by VEGF-A

为了生长超过最小尺寸，肿瘤必须产生新的血管。VEGF-A，由大多数 恶性肿瘤主要负责肿瘤血管生成，并且在肿瘤血管生成中具有不寻常的性质。 激活Ca 2+级联反应和诱导血管通透性过高的血管生成因子。 高渗透性是新形成的肿瘤血管的特征性特征， 肿瘤血管生成和间质形成。分泌VEGF-A的肿瘤诱导的新生血管 至少有6种不同的类型，并且使用经过改造以表达VEGF-A164的腺病毒载体，我们已经 能够在各种正常小鼠组织中生成每种血管类型的替代形式。的 在几种类型的肿瘤血管中，母血管（MV）是最先形成的，并且是主要的肿瘤血管。 高渗透性血管亚群MV是过度表达VEGFR-1的大大增大的周细胞贫乏的窦状隙 和-2;它们也是在许多快速生长的小鼠肿瘤中发现的最常见的血管类型， 在人类肿瘤中也很常见。我们已经发现VEGF-A的许多血管生成活性是 通过孤儿核转录因子TR 3（人）/Nur 77（小鼠）介导。我们的整体 假设TR 3/Nur 77在调节VEGF-A诱导的血管生成中具有重要的作用， 渗透性，血管超微结构和肿瘤血管生成的最早阶段，导致形成 高渗透性的母血管两个具体目标将检验这一中心假设：目标1。量化 Nur 77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的Nur 77-/-和转基因Nur 77-S小鼠，以及Aim 2。阐明 激活Ca 2+和调节TR 3表达和转录活性的信号通路， 培养的内皮细胞和体内基质胶塞测定中。这些目标利用不同的技术 聚焦于单一目标，阐明VEGF-A诱导TR 3/Nur 77的步骤和机制 表达和激活，以及血管生成和相关的血管通透性过高。 与公共卫生的相关性：这些研究将阐明肿瘤启动形成的机制。 他们需要新的血管生长和生存，并在此过程中，确定新的潜力， 用于攻击肿瘤脉管系统的靶点和介入点。

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.