Orphan Nuclear Receptor TR3 in tumor angiogenesis and associated microvessel perm

描述（由申请人提供）：为了生长超过最小尺寸（3 mm 3），肿瘤必须产生新的血管供应（血管生成），用于气体交换、细胞营养和废物处理。在众多的血管生成因子中，VEGF-A在肿瘤血管生成和相关的微血管对血浆蛋白的通透性中是最重要的。VEGF-A165的人源化抗体Avastin已经被开发出来，并显示出在治疗几种类型的癌症中是有效的。然而，Avastin具有显著的毒副作用。因此，需要鉴定VEGF信号传导的下游靶标是否可以用作具有较小毒性作用的有希望的治疗靶标。我们最近的工作表明，孤儿核受体TR 3（小鼠类似物，Nur 77）在培养的内皮细胞和病理性血管生成中被VEGF-A165高度上调，并且它是VEGF-A165诱导的体外内皮细胞增殖和存活以及体内Matrigel血管生成所必需的。TR 3 cDNA的过表达诱导内皮细胞增殖和存活在体外和基质胶血管生成在体内，即使在VEGF-A165的情况下。TR 3的转录活性是其在血管生成中的功能所必需的。此外，B16黑色素瘤生长在Nur 77-/-小鼠中被完全抑制，最有可能是通过抑制肿瘤血管生成。Nur 77-/-小鼠无明显发育缺陷。我们的总体假设是TR 3/Nur 77通过调节血管生成和相关的微血管通透性来调节肿瘤生长。为了证明我们的假设并深入了解分子机制，我们将研究在Aim 1中Nur 77活性在小鼠内皮中被抑制的转基因小鼠中的肿瘤生长。我们的第二个目标是研究TR 3/Nur 77通过使VE-钙粘蛋白粘附连接不稳定来调节肿瘤血管生成及其相关的微血管通透性。在最后一个目标中，我们将描绘TR 3调控VE-钙粘蛋白表达的转录机制。这项研究的信息不仅将增强我们对肿瘤发生的病理生理学的理解，而且还将帮助我们开发有效的治疗癌症的治疗方法。公共卫生相关性：肿瘤生长的机制在很大程度上是未知的。我们目前的建议将确定Nur 77是癌症治疗的一个很好的靶点。

DESCRIPTION (provided by applicant): In order to grow beyond minimal size (3 mm3), tumors must generate a new vascular supply (angiogenesis) for the purpose of gas exchange, cell nutrition, and waste disposal. Among many angiogenic factors, VEGF-A has been shown to be the most important one in tumor angiogenesis and associated microvessel permeability to plasma proteins. A humanized antibody to VEGF-A165, Avastin, has been developed and shown to be effective in treating several types of cancers. However, Avastin has significant toxic side effects. Therefore, it is desirable to identify whether downstream targets of VEGF signaling can be used as promising therapeutic targets with less toxic effects. Our recent work showed that the orphan nuclear receptor TR3 (mouse analogue, Nur77) was highly upregulated by VEGF-A165 in cultured endothelial cells and in pathological angiogenesis and that it was required for VEGF-A165-induced endothelial cell proliferation and survival in vitro and Matrigel angiogenesis in vivo. Overexpression of TR3 cDNA induced endothelial cell proliferation and survival in vitro and in Matrigel angiogenesis in vivo, even in the absence of VEGF-A165. The transcriptional activity of TR3 is required for its function in angiogenesis. Further, B16 melanoma growth was completely inhibited in Nur77-/- mice, most likely through inhibition of tumor angiogenesis. Nur77-/- mice have no obvious developmental defect. Our overall hypothesis is that TR3/Nur77 regulates tumor growth through regulation of angiogenesis and associated microvessel permeability. To prove our hypothesis and gain insight into the molecular mechanisms, we will study tumor growth in transgenic mice that Nur77 activity is inhibited in mouse endothelium in Aim 1. Our second aim will investigate that TR3/Nur77 regulates tumor angiogenesis and its associated microvessel permeability by destabilization of VE-cadherin adherences junctions. In the last aim, we will delineate the transcriptional mechanisms by which TR3 regulates VE-cadherin expression. The information from this study will not only enhance our understanding of the pathophyiosiology of tumorigenesis but also help us to develop effective therapeutic approaches for treatment of cancers. PUBLIC HEALTH RELEVANCE: The mechanism of tumor growth is largely unknown. Our current proposal will identify that Nur77 is an excellent target for cancer therapy.