IGF SIGNAL TRANSDUCTION PATHWAY IN MEDULLOBLASTOMA

髓母细胞瘤中的 IGF 信号转导途径

• 批准号: 6825073
• 负责人: Krzysztof Reiss
• 金额: $ 25.98万
• 依托单位: TEMPLE UNIV OF THE COMMONWEALTH
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-30 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6825073
• 关键词: Papovaviridae; antigen antibody reaction; biological signal transduction; cell line; growth factor receptors; human tissue; immunoprecipitation; insulinlike growth factor; medulloblastoma; neoplastic transformation; pathologic process; phosphorylation; polymerase chain reaction; receptor expression; site directed mutagenesis; tumor antigens; viral carcinogenesis; western blottings

Project #3: IGF-Signal Transduction Pathway in Medulloblastoma A considerable line of evidence points at the IGF-I auto/paracrine system as an important component in the development and progression of brain tumors. Despite this, little attention has been paid to the role of IGF-I receptor (IGF-IR), and its signaling pathways, in primitive neuroectodermal tumors/ medulloblastomas (PNETs/MBs) that represent about 25% of all pediatric brain tumors. This research proposal is founded on the hypothesis that the IGF-IR system and the JCV T-antigen cooperate in the development and/or progression of medulloblastomas. Importance of this hypothesis is supported by several findings: (i) JC virus (JCV) infects greater than 80% of the human population; (ii) JCV T-antigen was found in human tumors including PNET/MBs; (iii) ectopic expression of JCV T-antigen transforms cells in culture and is tumorogenic in experimental animals; and (iv) JCV T-antigen, as well as, its murine counterpart - SV40 T-antigen, are not able to transform cells that do not possess functional IGF-IR. To further support our hypothesis, we have developed new evidence demonstrating overexpression of the major IGF-IR substrate, IRS-1, in both human and mouse medulloblastoma cell lines, and the activation of IGF-I system including constitutive phosphorylation of the IGF-IR protein in biopsies from patients with medulloblastoma. We have also found that both JCV-T-antigen and IGF-IR are necessary for medulloblastoma cell lines to survive and grow in anchorage-independent culture condition, and finally, we have demonstrated that JCV T-antigen and IRS-1 interact with each other. Three specific aims are proposed to directly test the hypothesis on the functional role for IGF-1 signaling pathway in the genesis of medulloblastoma; in the first aim mutational analysis of the IGF-IR will be utilized to determine whether functional interaction between the IGF-IR and JCV T-antigen contributes to malignant transformation in medulloblastomas; in the second aim JCV T-antigen positive and negative medulloblastoma cell lines will be employed to determine whether a unique set of IGF-IR pathways is involved in JCV T-antigen mediated transformation. Metabolic inhibitors in combination with mutational analysis of signaling molecules, including IRS-1 and PTEN phosphatase, will be employed to alter IGF-IR pathways and to test their importance in both T-antigen and non T-antigen mediated transformation; finally in the third aim dominant negative strategies against the IGF-IR and IRS-1 function will be tested in vivo. The results of these in vivo studies will allow us to evaluate whether uncoupling of the IGF-IR signaling pathway/s from its functional synergy with JCV T-antigen will eliminate medulloblastoma tumors from cerebellar tissues.

项目#3：髓母细胞瘤中的 IGF 信号转导途径 大量证据表明 IGF-I 自动/旁分泌系统是脑肿瘤发生和进展的重要组成部分。尽管如此，IGF-I 受体 (IGF-IR) 及其信号通路在原始神经外胚层肿瘤/髓母细胞瘤 (PNET/MB) 中的作用却很少受到关注，原始神经外胚层肿瘤/髓母细胞瘤 (PNET/MB) 约占所有儿童脑肿瘤的 25%。本研究提案基于以下假设：IGF-IR 系统和 JCV T 抗原在髓母细胞瘤的发生和/或进展中相互配合。这一假设的重要性得到了多项发现的支持：(i) JC 病毒 (JCV) 感染超过 80% 的人口； (ii) 在包括 PNET/MB 在内的人类肿瘤中发现了 JCV T 抗原； (iii) JCV T抗原的异位表达会转化培养物中的细胞，并且在实验动物中具有致瘤性； (iv) JCV T-抗原及其鼠对应物-SV40 T-抗原不能转化不具有功能性IGF-IR的细胞。为了进一步支持我们的假设，我们开发了新的证据证明 主要 IGF-IR 底物 IRS-1 在人和小鼠髓母细胞瘤细胞系中的过度表达，以及 IGF-I 系统的激活，包括髓母细胞瘤患者活检组织中 IGF-IR 蛋白的组成型磷酸化。我们还发现 JCV-T 抗原和 IGF-IR 对于髓母细胞瘤细胞系在不依赖贴壁的培养条件下生存和生长是必需的，最后，我们证明了 JCV T 抗原和 IRS-1 相互作用。提出了三个具体目标来直接检验 IGF-1 信号通路在髓母细胞瘤发生中的功能作用的假设；第一个目标是利用 IGF-IR 突变分析来确定 IGF-IR 和 JCV T 抗原之间的功能性相互作用是否有助于髓母细胞瘤的恶性转化；第二个目标将采用 JCV T 抗原阳性和阴性髓母细胞瘤细胞系来确定一组独特的 IGF-IR 途径是否参与 JCV T 抗原介导的转化。代谢抑制剂与信号分子（包括 IRS-1 和 PTEN 磷酸酶）的突变分析相结合，将用于改变 IGF-IR 途径并测试它们在 T 抗原和非 T 抗原介导的转化中的重要性；最后，在第三个目标中，将在体内测试针对 IGF-IR 和 IRS-1 功能的显性阴性策略。这些结果在 体内研究将使我们能够评估 IGF-IR 信号通路与 JCV T 抗原的功能协同作用的解偶联是否会消除小脑组织中的髓母细胞瘤。