VHL and FGFR signaling in angiogenesis

描述（由申请人提供）：von HippeI-Lindau （VHL）综合征是一种以高度血管化肿瘤发展为特征的遗传性疾病。其潜在的遗传缺陷是在VHL肿瘤抑制基因。因此，VHL突变体为研究肿瘤诱导的血管生成提供了一个极好的系统。我们已经确定了一种进化保守的新型突变机制，该机制导致VHL突变体中FGF受体（FGFR）在细胞表面过度积累。这种现象在果蝇、恶性肾细胞癌（RCC）培养中都观察到，也可能在人微血管内皮细胞（HMVECs）中观察到。研究还指出，过度积累的FGFR会导致异常的细胞迁移和诱导Ets1活性，其功能与转移和血管生成有关。我们之前发现VHL的功能可能是由另一种肿瘤抑制基因nm23介导的。基于这些初步数据，研究人员提出了一种新的细胞内机制，该机制是VHL和nm23突变（如人类VHL疾病患者和果蝇发育突变）中FGFR积累表型的基础，以及这种异常信号事件如何通过Ets1调节血管生成过程中的细胞运动。我们将利用体外和体内模型系统，并采用跨物种比较研究来剖析信号机制。目的1将剖析导致FGFR过度积累的囊泡运输途径。目的2将分析VHL、FGFR和Ets1在调节血管生成中的作用，采用三维共培养系统。目的3将研究VHL与Nm23相关的新功能。Aim 4将使用敲除小鼠来验证VHL病患者内皮细胞的杂合突变在该疾病高度血管化的致瘤特性中起重要作用的假设。

DESCRIPTION (provided by applicant): The von HippeI-Lindau (VHL) syndrome is a hereditary disease that is characterized by the development of highly vascularized tumors. Its underlying genetic defect is in the VHL tumor suppressor gene. The VHL mutant therefore represents an excellent system for studying the tumor-induced angiogenesis. We have identified an evolutionarily conserved novel mutational mechanism that leads to FGF receptor (FGFR) over-accumulation on the cell surface in VHL mutants. This phenomenon is observed in Drosophila, in the malignant renal cell carcinoma (RCC) culture, and likely in the human microvascular endothelial cells (HMVECs). It was also noted that the over-accumulated FGFR leads to aberrant cell migration and induction of Ets1 activity, whose function has been linked to metastasis and angiogenesis. We have previously found that the function of VHL is likely mediated by another tumor suppressor gene nm23. Based on these preliminary data, a novel intracellular mechanism is proposed that underlies the FGFR accumulation phenotype in VHL and nm23 mutations (as in human VHL disease patients and in Drosophila developmental mutant) and how this aberrant signaling event, via Ets1, can modulate cell motility during angiogenesis. We will utilize in vitro and in vivo model systems and employ cross-species comparative studies to dissect the signaling mechanisms. Aim 1 will dissect the vesicle transport pathway that results in FGFR over-accumulation. Aim 2 will analyze the role of VHL, FGFR, and Ets1 in modulating angiogenesis, employing a 3-dimensional co-culture system. Aim 3 will examine the novel function of VHL in relation to Nm23. Aim 4 will employ knockout mice to test the hypothesis that VHL heterozygous mutation in endothelial cells in the VHL disease patients play an important role in the disease' highly vascularized tumorigenic characteristics.