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（由申请人提供）：在过去的几年中，RAS的小型GTPase致癌基因一直是癌症研究的重点，因为它是与所有人类癌症相关的最常见突变基因之一（33％）。 RAS是小型GTPase的大型超家族的创始成员，最近的研究将异常活性与涉及RAS超家族蛋白的异常活动联系在一起，尤其是RAS同源（RHO）GTPases与肿瘤发生联系。但是，与RA不同，Rho GTPases并未直接在癌症中突变，而是它们的异常活性与它们的异常表达和/或调节有关。可能是出现的最重要的机制，其中Rho GTPase的异常活性是激活称为RhoGEFS（鸟嘌呤核苷酸交换因子）的蛋白质异常的结果。我的研究集中在一个Rhogef，ECT2（上皮细胞转化序列2）上。 ECT2是Rhogefs人类DBL家族的成员。先前的研究表明，ECT2在正常的哺乳动物细胞因子中至关重要。相比之下，在许多癌症中已经观察到了ECT2异常的过表达，最近的一项研究表明，ECT2在肺癌细胞系生长和肿瘤性中的关键作用。我们发现，在结直肠癌（CRC）患者肿瘤组织，具有自发性肠腺瘤的APCMIN小鼠和人CRC细胞系中，ECT2表达升高。有证据表明，在正常细胞核中存在的ECT2被错误地定位在肺和脑癌中的细胞质中。这种错误定位可能导致细胞质中的不适当的RHO激活。除了其Rhogef催化结构域，ECT2还由多个加法结构域组成。在癌症中如何异常激活ECT2，以及在正常和肿瘤细胞中ECT2功能的机制是否不同，了解不足和我的研究重点。我们假设ECT2在细胞因子中的功能与促进肿瘤发生的功能不同，并且错误定位可能导致癌症的ECT2激活。这些研究将需要我应用非常多样化的实验技术曲目，将我的发展促进独立研究人员，并确定我进行基本和转化癌症研究的能力。 公共卫生相关性：像RAS癌蛋白一样，异常RHO（RAS同源；但是，尽管RAS的直接突变导致其激活，但间接机制导致RHO激活。我们的初步发现确定了结直肠癌（CRC）中ECT2，鸟嘌呤核苷酸交换因子（Rhogef）和Rho激活剂的过表达。尽管ECT2与正常细胞因子有关，但我们假设ECT2的异常过表达和错误定位会促进CRC肿瘤肿瘤，侵入性和转移性生长。我们建议研究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。新兴的兴趣是，Rhogefs可能是癌症药物发现的重要新蛋白质靶标。我们的研究将为ECT2在CRC中的重要性提供验证，并为ECT2激活的机制和治疗干预的肿瘤发生提供了验证。研究结直肠癌的意义：CRC是美国癌症死亡的第三个主要原因，尽管CRC有许多有针对性的治疗选择（例如，贝伐单抗和Cetuximab）仍然需要新的和改善的分子靶向的新需要。