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：髓母细胞瘤的IGF信号转导途径 大量证据指向IGF-1自动/旁分泌系统是脑肿瘤发育和进展的重要组成部分。尽管如此，在原始神经外科肿瘤/髓母细胞瘤（PNETS/ MBS）中，IGF-I受体（IGF-IR）及其信号通路的作用几乎没有引起关注。该研究提案建立在以下假设的基础上：IGF-IR系统和JCV T抗原在髓母细胞瘤的发展和/或进展中合作。该假设的重要性得到了几个发现的支持：（i）JC病毒（JCV）感染了超过80％的人口； （ii）在包括PNET/MB在内的人类肿瘤中发现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肿瘤性； （iv）JCV t-抗原以及其鼠类对应物-SV40 T-抗原，无法转化不具有功能性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 在人和小鼠髓母细胞瘤细胞系中，主要IGF-IR底物IRS-1的过表达以及IGF-I系统的激活，包括来自髓母细胞瘤患者的活检中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都是必要的 JCV T-抗原和IRS-1相互作用。提出了三个特定的目的，以直接检验髓母细胞瘤起源中IGF-1信号通路功能作用的假设。在第一个目标中，将利用对IGF-IR的突变分析来确定IGF-IR和JCV T抗原之间的功能相互作用是否有助于髓母细胞瘤中的恶性转化；在第二个目标中，JCV T抗原阳性和阴性髓母细胞瘤细胞系将用于确定JCV T抗原介导的转化是否涉及独特的IGF-IR途径。代谢抑制剂与包括IRS-1和PTEN磷酸酶在内的信号分子的突变分析相结合，用于改变IGF-IR途径，并测试其在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，针对IGF-IR和IRS-1功能的负面负面策略将在体内进行测试。这些结果 体内研究将使我们能够评估IGF-IR信号传导途径与JCV T抗原的功能协同作用是否会消除小脑组织中的髓母细胞瘤肿瘤。