Novel Functions for Ras family GTPases

Ras 家族 GTPases 的新功能

基本信息

批准号：
9240249
负责人：
John P O'Bryan
金额：
--
依托单位：
JESSE BROWN VA MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-10-01 至 2020-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9240249
关键词：
1-Phosphatidylinositol 3-Kinase Address Affect Affinity Amino Acids Animal Cancer Model Area Binding Binding Proteins Biological Biology Biomedical Research Cell Fraction Cell model Cell physiology Cells Chronic Colorectal Cancer Data Development Environment Eukaryota Exhibits Extracellular Domain Family Family member Funding GTP Binding General Population Goals Growth Growth Factor Oncogenes Guanine Nucleotide Exchange Factors Guanosine Triphosphate Guanosine Triphosphate Phosphohydrolases HRAS gene Health Human Human Biology In Vitro Incidence KRAS2 gene Knowledge Lung Malignant Neoplasms Malignant neoplasm of lung Malignant neoplasm of pancreas Measures Mediating Medical Modeling Molecular Molecular Conformation Mutate Mutation Normal Cell Nucleotides Oncogenes Oncogenic Oxidation-Reduction Pancreas Phosphotransferases Play Population Prevalence Proteins RAS genes Reagent Regulation Reporting Repression Research Research Personnel Risk Role Signal Pathway Signal Transduction Signal Transduction Pathway Specificity Technology Tertiary Protein Structure Veterans Work base cancer therapy chemical genetics genetic approach improved in vivo inhibitor/antagonist insight interest malignant breast neoplasm mutant novel pancreatic tumorigenesis predictive modeling prevent programs ras Proteins receptor steroid hormone receptor tool tumor tumorigenesis

项目摘要

Project Summary: Ras proteins play a central role in many aspects of biology. These monomeric GTPases cycle between an inactivate GDP-bound state and an active GTP-bound state. Mutational activation of Ras occurs in approximately 30% of human tumors with some cancers such as pancreatic cancer having Ras mutations in >90% of tumors. These cancer associated mutations trap Ras in the GTP-bound state, leading to chronic activation of Ras-regulated signaling pathways and oncogenic transformation. Thus, RasGTP has been considered the only biologically important form of the molecule. However, we have discovered a novel role for nucleotide-free Ras (nfRas) in the negative regulation of cell signaling. This form of Ras, formed as an intermediate in the transition from RasGDP to RasGTP, negatively regulates phosphatidylinositol 3-kinase, class 2beta (PI3KC2β). These finding have profound implications for the understanding of Ras-mediated signaling and transformation. We propose that nfRas binds targets, e.g., PI3KC2β, leading to the mutual inhibition of both Ras and the associated target. Our model predicts that oncogenic activation of Ras leads to loss of repression of these targets resulting in their activation without binding RasGTP. Thus, our findings point to a new class of molecules important for Ras-driven tumorigenesis yet do not bind activated Ras. To better understand the role of nfRas in cell signaling, we have generated high affinity, high specificity monobody reagents that selectively bind different states of Ras. Using these reagents we demonstrate that nfRas represents a significant pool of total cellular Ras. In addition, one of our Ras monobodies which binds to all three forms of Ras (GTP, GDP, and nucleotide free) acts as a highly potent inhibitor of oncogenic Ras- mediated signaling. Using these reagents we will characterize the regulation of nfRas in vivo and determine the role of nfRas in regulating specific targets. Finally, we will utilize these novel monobody reagents to perturb Ras function in vivo using a novel chemical-genetic approach to interfere with pancreatic cancer development and progression. Given the prevalence of Ras mutations in human cancers, it is critical to understand the mechanisms through which Ras contributes to tumorigenesis. Our work represents an entirely new concept in Ras biology that defines a new class of targets that participate in Ras-mediated signaling and transformation. These studies will provide new insights into the mechanisms of Ras-mediated tumorigenesis and are therefore of high translational significance. This work will be beneficial to Veterans as well as the general population, both of which suffer from cancer. However, the incidence for certain cancers, such as lung and pancreatic cancer the latter of which has a high incidence of Ras mutations (<90%), has been reported to be up to 5-7x higher in Veteran populations making these studies particularly relevant to Veterans. Additionally, the goals of our proposal are consistent with the recently established National Cancer Moonshots Program to accelerate research efforts to improve cancer treatment. Finally, given the ubiquity of Ras family members in eukaryotes and their roles in many aspects of biology these results will be of broad scientific interest and importance to many areas of biomedical research.

项目概要： Ras 蛋白在生物学的许多方面发挥着核心作用。失活的 GDP 结合状态和活跃的 GTP 结合状态发生在 Ras 的突变激活中。大约 30% 的人类肿瘤（例如胰腺癌）具有 Ras 突变 > 90% 的肿瘤相关突变使 Ras 处于 GTP 结合状态，从而导致慢性癌症。因此，RasGTP 已被认为可以激活 Ras 调节的信号通路和致癌转化。被认为是该分子唯一具有生物学意义的形式。然而，我们发现了它的新作用。无核苷酸 Ras (nfRas) 参与细胞信号传导的负调控。从 RasGDP 过渡到 RasGTP 的中间体，负向调节磷脂酰肌醇 3-激酶， 2beta (PI3KC2β) 的这些发现对于理解 Ras 介导具有深远的意义。我们建议 nfRas 结合靶标，例如 PI3KC2β，从而产生相互的作用。我们的模型预测 Ras 的致癌激活会导致 Ras 和相关靶点的抑制。对这些靶标的抑制作用消失，导致它们在不结合 RasGTP 的情况下被激活。因此，我们的研究结果表明。对 Ras 驱动的肿瘤发生很重要的一类新分子，但不能更好地结合激活的 Ras。针对nfRas在细胞信号传导中的作用，我们生成了高亲和力、高特异性的单体选择性结合 Ras 不同状态的试剂使用这些试剂，我们证明了 nfRas。代表了一个重要的总细胞 Ras 库。此外，我们的 Ras 单体之一可与所有细胞结合。三种形式的 Ras（GTP、GDP 和无核苷酸）可作为致癌 Ras 的高效抑制剂使用这些试剂，我们将表征 nfRas 的体内调节并确定最后，我们将利用这些新型单体试剂来干扰 nfRas 在调节特定靶标中的作用。 Ras 在体内发挥作用，利用新型化学遗传方法干扰胰腺癌的发展鉴于 Ras 突变在人类癌症中的普遍存在，了解 Ras 突变的发生至关重要。 Ras 促进肿瘤发生的机制我们的工作代表了一个全新的概念。 Ras 生物学定义了一类新的靶标，参与 Ras 介导的信号传导和这些研究将为Ras介导的肿瘤发生机制提供新的见解。因此，这项工作将有益于退伍军人和民众。一般人群都患有癌症，但是某些癌症的发病率较高，例如肺癌。据报道，胰腺癌 Ras 突变发生率很高（<90%）退伍军人群体的比例高达 5-7 倍，这使得这些研究与退伍军人特别相关。我们提案的目标与最近制定的国家癌症登月计划一致最后，考虑到 Ras 家族成员在世界各地的普遍存在，加快研究工作以改善癌症治疗。真核生物及其在生物学许多方面的作用这些结果将具有广泛的科学意义对生物医学研究的许多领域都具有重要意义。