Elucidating the Molecular Mechanisms of Ect2 in cytokinesis and oncogenesis

阐明 Ect2 在胞质分裂和肿瘤发生中的分子机制

• 批准号: 8129902
• 负责人: Danielle Ryan Cook
• 金额: $ 4.04万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-26 至 2014-07-25
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8129902
• 关键词: Accounting; Address; Anchorage-Independent Growth; Antineoplastic Agents; Cancer Etiology; Cancer cell line; Catalytic Domain; Cell Culture Techniques; Cell Line; Cell Nucleus; Cell physiology; Cessation of life; Cetuximab; Colon; Colorectal Cancer; Confusion; Cytokinesis; Cytoplasm; Development; Disease; Embryo; Epithelial Cells; Family; Fibroblasts; Fostering; Genes; Growth; Guanine Nucleotide Exchange Factors; Guanosine Triphosphate Phosphohydrolases; Human; In Vitro; Intestines; Large Intestine Carcinoma; Lead; Link; Lung Neoplasms; Malignant Epithelial Cell; Malignant Neoplasms; Malignant neoplasm of brain; Malignant neoplasm of lung; Modeling; Molecular; Monomeric GTP-Binding Proteins; Mus; Mutate; Mutation; Nature; Neoplasm Metastasis; Normal Cell; Oncogene Proteins; Oncogenes; Oncogenic; Patients; Phenotype; Property; Proteins; RNA Interference; Regulation; Research Personnel; Role; Signal Transduction; Techniques; Therapeutic Intervention; Tumor Cell Invasion; Tumor Cell Line; Tumor Tissue; Tumorigenicity; Validation; adenoma; anticancer research; base; bevacizumab; cancer cell; design; drug discovery; improved; in vitro Assay; in vivo; interest; knock-down; lung Carcinoma; matrigel; member; mouse model; mutant; neoplastic; neoplastic cell; overexpression; small hairpin RNA; therapeutic target; tumor growth; tumorigenesis; tumorigenic

DESCRIPTION (provided by applicant): In previous years, Ras, a small GTPase oncogene has been a focus in cancer research because it is one of the most commonly mutated genes associated with all human cancers (33%). Ras is the founding member of a large superfamily of small GTPases, and recent studies have linked the abnormal activity implicated Ras superfamily proteins, in particular, the Ras homologous (Rho) GTPases to tumorigenesis. However, unlike Ras, Rho GTPases are not mutated directly in cancer, but instead their abnormal activity has been linked to their abnormal expression and/or regulation. Perhaps the most significant mechanism that has emerged in which aberrant activity of Rho GTPase is the result of abnormalities in activating proteins called RhoGEFs (guanine nucleotide exchange factors). My studies are focused on one RhoGEF, Ect2 (Epithelial cell transforming sequence 2). Ect2 is a member of the human Dbl family of RhoGEFs. Previous studies indicate that Ect2 is essential in normal mammalian cytokinesis. In contrast, abnormal overexpression of Ect2 has been observed in many cancers, and a recent study demonstrated a critical role for Ect2 in lung carcinoma cell line growth and tumorigenicity. We have found that Ect2 expression is elevated in colorectal carcinoma (CRC) patient tumor tissue, APCmin mice with spontaneous intestinal adenomas, and human CRC cell lines. There is evidence that Ect2, which is present in the nucleus of normal cells, is mislocalized into the cytoplasm in lung and brain cancers. This mislocalization may lead to inappropriate Rho activation in the cytoplasm. In addition to its RhoGEF catalytic domain, Ect2 is comprised of multiple addition domains. How Ect2 becomes aberrantly activated in cancer and whether the mechanisms of Ect2 function in normal and neoplastic cells are distinct, are poorly understood and the focus of my studies. We hypothesize that the functions of Ect2 in cytokinesis are distinct from functions which promote oncogenesis and that mislocalization may contribute to Ect2 activation in cancer. These studies will require my application of a very diverse repertoire of experimental techniques, foster my development into an independent researcher and establish my abilities to do basic and translational cancer research. PUBLIC HEALTH RELEVANCE: Like the Ras oncoprotein, aberrant Rho (Ras homologous; e.g., RhoA, Rac1 and Cdc42) small GTPase signal transduction is also implicated in human oncogenesis. However, whereas direct mutation of Ras leads to its activation, indirect mechanisms lead to Rho activation. Our preliminary findings identified overexpression of Ect2, a guanine nucleotide exchange factor (RhoGEF) and Rho activator, in colorectal cancer (CRC). While Ect2 has been implicated in normal cell cytokinesis, we hypothesize that the aberrant overexpression and mislocalization of Ect2 promotes CRC tumorigenic, invasive and metastatic growth. We propose studies cell culture and mouse model studies to address the role and mechanism of Ect2 in normal and neoplastic cellular function. There is emerging interest that RhoGEFs may be an important new class of protein targets for cancer drug discovery. Our studies will provide validation for Ect2 importance in CRC and eludicate mechanisms of Ect2 activation and oncogenesis for therapeutic intervention. Significance of studying colorectal cancer: CRC is the 3rd leading cause of cancer deaths in the US and while there are a number of targeted therapeutic options available for CRC (e.g., bevacizumab and cetuximab) there is still a dire need for new and improved molecularly-targeted therapies.

描述(申请人提供)：RAS，一个小的GTP酶癌基因，在过去几年一直是癌症研究的焦点，因为它是与所有人类癌症相关的最常见的突变基因之一(33%)。RAS是一个小的GTP酶超家族的创始成员，最近的研究将RAS超家族蛋白，特别是Ras同源(Rho)GTP酶的活性异常与肿瘤的发生联系起来。然而，与RAS不同的是，Rho GTP酶在癌症中不会直接突变，而是与其异常表达和/或调节有关。Rho GTP酶活性异常的最重要机制可能是被称为RhoGEF(鸟嘌呤核苷酸交换因子)的激活蛋白异常所致。我的研究主要集中在一个Rhogef，ECT2(上皮细胞转化序列2)。ECT2是人类DBL家族RhoGEF的成员之一。以往的研究表明，ECT2在正常哺乳动物的胞质分裂中是必不可少的。相反，在许多癌症中都观察到了ECT2的异常过表达，最近的一项研究表明，ECT2在肺癌细胞系的生长和肿瘤发生中起着关键作用。我们发现ECT2在结直肠癌(CRC)患者肿瘤组织、APCmin自发性肠腺瘤小鼠和人CRC细胞系中表达升高。有证据表明，存在于正常细胞核中的Ect2在肺癌和脑癌中错误定位于细胞质中。这种错误的定位可能会导致Rho在细胞质中被不适当的激活。除了它的Rhogef催化结构域之外，Ect2还由多个加成结构域组成。ECT2如何在癌症中异常激活，以及ECT2在正常细胞和肿瘤细胞中的作用机制是否不同，这些都是鲜为人知的，也是我研究的重点。我们假设ECT2在胞质分裂中的功能与促进肿瘤发生的功能是不同的，错误的定位可能有助于在癌症中激活ECT2。这些研究将需要我应用非常多样化的实验技术，培养我成为一名独立的研究人员，并建立我进行基础和转化性癌症研究的能力。 公共卫生相关性：与RAS癌蛋白一样，异常的Rho(Ras同源；例如，RhoA、rac1和CDC42)小GTP酶信号转导也与人类肿瘤的发生有关。然而，RAS的直接突变导致其激活，间接机制导致Rho激活。我们的初步研究发现，在结直肠癌中，鸟嘌呤核苷酸交换因子和Rho激活子ECC2过表达。虽然ect2与正常细胞胞质分裂有关，但我们推测ect2的异常过表达和错误定位促进了结直肠癌的发生、侵袭和转移。我们建议进行细胞培养和小鼠模型研究，以解决ECT2在正常和肿瘤细胞功能中的作用和机制。人们越来越感兴趣的是，RhoGEF可能是癌症药物发现的一类重要的新蛋白质靶点。我们的研究将证实ECT2在结直肠癌中的重要性，并为治疗干预提供ECT2激活和肿瘤发生的机制。研究结直肠癌的意义：结直肠癌是美国癌症死亡的第三大原因，虽然结直肠癌有许多靶向治疗选择(例如贝伐单抗和西妥昔单抗)，但仍然迫切需要新的和改进的分子靶向治疗。