ELMO1, Dock180 and Glioma Invasion

ELMO1、Dock180 和神经胶质瘤侵袭

• 批准号: 7873025
• 负责人: Shi-Yuan Cheng
• 金额: $ 31万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-11 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7873025
• 关键词: 1-Phosphatidylinositol 3-Kinase; Address; Area; Attenuated; Binding; Biological Models; Brain; Caenorhabditis elegans; Cells; Clinical; Cytokinesis; Diffuse; Drosophila genus; Embryo; Epidermal Growth Factor Receptor; F-Actin; Failure; Fibroblasts; Genetic; Glioma; Goals; Growth; Guanine Nucleotide Exchange Factors; Human; In Vitro; Infiltration; Lead; Malignant - descriptor; Malignant Glioma; Mammalian Cell; Mediating; Membrane; Modeling; Molecular; Mus; Mutation; PTEN gene; Pathway interactions; Phosphorylation; Recurrence; Reporting; Resources; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Site; Slice; Specimen; Testing; Tyrosine Phosphorylation; Up-Regulation; Work; cell motility; epidermal growth factor receptor VIII; experience; glioma cell line; in vivo; insight; membrane activity; mutant; neoplastic cell; novel; polymerization; public health relevance; response; restoration; small hairpin RNA; therapeutic target; tumor; virtual

DESCRIPTION (provided by applicant): One of the common features of malignant human gliomas is the intrinsic ability of single tumor cells to disperse throughout the brain, rendering the virtual failure of all existing therapies to alter the growth of these deadly tumors. Currently, the mechanisms underlying the perilous invasiveness of glioma cells are poorly understood. Acquisition of malignant growth and insidious invasiveness by glioma cells involves multiple genetic alterations including mutations of epidermal growth factor receptor (EGFR) and PTEN. Genetic studies showed that the most common form of EGFR mutants, EGFRvIII and PTEN loss promote glioma cell invasion in the brain. Recently, we identified an up-regulation of engulfment and cell motility 1 (ELMO1) in invasive glioma cell lines. ELMO1 and its binding partner, dedicator of cytokinesis 1 (Dock180) function as a bipartite guanine nucleotide exchange factor (GEF) that activates Rac1 and promotes cell migration of C. elegans, Drosophila and mammalian cells. Using various model systems including analysis of a large number of primary human glioma specimens, we reported that this bipartite Rac1 GEF, ELMO1-Dock180 promotes glioma cell migration and invasion in vitro and ex vivo (brain slice model). Our preliminary studies reveal expression of EGFRvIII with ELMO1-Dock180 and loss of PTEN in invasive areas but not in central regions on these clinical glioma specimens. Exogenous expression of EGFRvIII by human glioma cell lines and short-term cultured primary human glioma cells with endogenous EGFRvIII displayed increases in Rac1 activity, tyrosine phosphorylation of ELMO1 and Dock180, and glioma cell motility. Inhibition of this GEF attenuated EGFRvIII-promoted cell motility. Additionally, knockdown of PTEN in EGFRvIII-expressing glioma cells resulted in induced tyrosine phosphorylation of endogenous ELMO1 and Dock180 and further enhanced cell motility. The goal of this proposal is to investigate the mechanisms by which EGFRvIII and PTEN modulate glioma cell invasion through the ELMO1-Dock180-Rac1 pathway and establish ELMO1-Dock180 as a therapeutic target for glioma treatment. Our central hypothesis is that EGFRvIII stimulates glioma cell invasion through ELMO1-Dock180 and loss of PTEN in EGFRvIII-expressing cells further enhances glioma cell invasion. We will address our hypotheses with three Specific Aims. In Specific Aim 1, we will test our hypothesis by determining the role of ELMO1-Dock180 in EGFRvIII-stimulated glioma cell motility. In Specific Aim 2, we will test our hypothesis by evaluating the effect of PTEN in EGFRvIII-ELMO1-Dock180-induced glioma cell motility. In Specific Aim 3, we will test our hypothesis by determining the impact of inhibition of ELMO1, Dock180, PTEN and their effectors on glioma cell invasion in the brain in invasive gliomas expressing EGFRvIII with known PTEN status. We have excellent model systems in place to test our hypotheses, extensive experience in characterization of glioma cell invasion and all of the necessary resources. The proposed studies could advance our understanding of the inherent ability of glioma cell infiltration and provide important strategies to limit the infiltration of glioma cells in the brain. This project has translational significance in providing new insights into intrinsic invasiveness of glioma cells and exploring approaches that impact the response to existing glioma therapies. PUBLIC HEALTH RELEVANCE: A hallmark of malignant gliomas is the intrinsic ability of single tumor cells to infiltrate throughout the brain, rendering these tumors virtually incurable by all existing therapies and also underlies their great propensity for recurrence. Therefore, further understanding of mechanisms underlying the aberrant cell motility during glioma invasion is imperative because it could lead to developing new strategies to treat malignant diffuse gliomas. In this proposal, we plan to determine the novel role of a bipartite guanine nucleotide exchange factor (GEF) composed of engulfment and cell motility 1 (ELMO1) and dedicator of cytokinesis 1 (Dock180) in glioma cell invasion and investigate the molecular mechanisms by which ELMO1-Dock180 mediate aberrant glioma cell infiltration into the brain. The proposed work has translational significance in providing new insights into intrinsic invasiveness of glioma cells and exploring approaches that impact the response to existing glioma therapies.

描述（由申请人提供）：恶性人类胶质瘤的一个共同特征是单个肿瘤细胞在整个大脑中分散的内在能力，这使得所有现有的治疗方法都无法改变这些致命肿瘤的生长。目前，神经胶质瘤细胞危险侵袭的机制尚不清楚。胶质瘤细胞的恶性生长和潜伏侵袭涉及多种遗传改变，包括表皮生长因子受体（EGFR）和PTEN的突变。遗传学研究表明，EGFR突变体最常见的形式是EGFRvIII和PTEN缺失，它们促进脑内胶质瘤细胞的侵袭。最近，我们在侵袭性胶质瘤细胞系中发现了吞噬和细胞运动1 （ELMO1）的上调。ELMO1及其结合伙伴细胞质分裂1的献花者（Dock180）作为一种双体鸟嘌呤核苷酸交换因子（GEF），激活Rac1，促进线虫、果蝇和哺乳动物细胞的细胞迁移。通过多种模型系统，包括对大量原发人胶质瘤标本的分析，我们报道了这一两部分Rac1 GEF， ELMO1-Dock180促进胶质瘤细胞在体外和体外的迁移和侵袭（脑切片模型）。我们的初步研究表明，在这些临床胶质瘤标本中，EGFRvIII与ELMO1-Dock180的表达和PTEN在侵袭区域的缺失，而不是在中心区域。外源性表达EGFRvIII的人胶质瘤细胞系和短期培养的具有内源性EGFRvIII的人胶质瘤原代细胞显示出Rac1活性、ELMO1和Dock180酪氨酸磷酸化以及胶质瘤细胞运动的增加。抑制该GEF可减弱egfrviii，促进细胞运动。此外，在表达egfrviii的胶质瘤细胞中，PTEN的下调导致内源性ELMO1和Dock180的酪氨酸磷酸化，进一步增强细胞的运动能力。本研究的目的是研究EGFRvIII和PTEN通过ELMO1-Dock180- rac1通路调节胶质瘤细胞侵袭的机制，并建立ELMO1-Dock180作为胶质瘤治疗的治疗靶点。我们的中心假设是EGFRvIII通过ELMO1-Dock180刺激胶质瘤细胞侵袭，而表达EGFRvIII的细胞中PTEN的缺失进一步增强了胶质瘤细胞的侵袭。我们将用三个具体目标来解决我们的假设。在Specific Aim 1中，我们将通过确定ELMO1-Dock180在egfrviii刺激的胶质瘤细胞运动中的作用来验证我们的假设。在Specific Aim 2中，我们将通过评估PTEN在egfrviii - elmo1 - dock180诱导的胶质瘤细胞运动中的作用来验证我们的假设。在Specific Aim 3中，我们将通过确定抑制ELMO1、Dock180、PTEN及其效应物对已知PTEN状态下表达EGFRvIII的侵袭性胶质瘤中脑胶质瘤细胞侵袭的影响来验证我们的假设。我们有优秀的模型系统来测试我们的假设，在表征胶质瘤细胞侵袭方面的丰富经验和所有必要的资源。这些研究有助于我们进一步了解胶质瘤细胞浸润的内在能力，并为限制胶质瘤细胞在大脑中的浸润提供重要的策略。该项目具有翻译意义，为胶质瘤细胞的内在侵袭性提供了新的见解，并探索了影响现有胶质瘤治疗反应的方法。公共卫生相关性：恶性神经胶质瘤的一个特征是单个肿瘤细胞浸润整个大脑的内在能力，这使得这些肿瘤几乎无法治愈，所有现有的治疗方法都无法治愈，也是其复发倾向的基础。因此，进一步了解胶质瘤侵袭过程中异常细胞运动的机制是必要的，因为它可能导致开发治疗恶性弥漫性胶质瘤的新策略。在本研究中，我们计划确定由吞噬和细胞运动1 （ELMO1）和细胞分裂专用因子1 （Dock180）组成的双联鸟嘌核苷酸交换因子（GEF）在胶质瘤细胞侵袭中的新作用，并研究ELMO1-Dock180介导胶质瘤细胞异常浸润的分子机制。提出的工作在提供胶质瘤细胞内在侵袭性的新见解和探索影响现有胶质瘤治疗反应的方法方面具有翻译意义。