Identifying c-Cbl as a critical point of intervention in glioblastoma multiforme

描述(申请人提供)：多形性胶质母细胞瘤(GBM)仍然是最具破坏性的中枢神经系统恶性肿瘤，在过去几十年的治疗开发方面进展甚微。以广泛的生长、广泛的血管形成和显著的化疗耐药为特征，GBM不可避免地复发，尽管接受了治疗，但仅与14个月的生存预后有关。以前的工作[13]已经发现了一种新的调控途径(氧化还原/Fyn/c-Cbl(RFC))，该途径存在于中枢神经系统的前体细胞中，似乎在GBM中调节失调。抑制E3泛素连接酶c-Cbl的正常调节，通过受体酪氨酸激酶(RTK)维持促有丝分裂信号，并使人对化疗药物产生耐药性。推测c-Cbl参与了多种细胞内信号通路，暗示c-Cbl是介导GBM病理的整合网络中的一个潜在的汇聚点。初步数据表明，粘着斑激酶(FAK)和热休克蛋白90(HSP90)都是c-Cbl功能障碍的贡献者，这促使了一项研究，即通过药物抑制这些化合物来挽救正常的c-Cbl调节。因此，本建议旨在验证以下假设：1)药物抑制FAK可恢复正常的c-Cbl功能，并使其能够靶向GBM细胞；2)药物抑制HSP90也可恢复正常的c-Cbl活性，从而能够靶向治疗GBM细胞；3)在人的异种移植小鼠GBM模型中，FAK和HSP90的小分子抑制剂可恢复c-Cbl的活性并显示出治疗相关性。在药物抑制剂和化疗药物存在的情况下，将结合蛋白质相互作用、细胞活力、RTK降解和癌症干细胞表型的分析，来测试c-Cbl功能在这些效应中的重要性。我们的首要目标是确定FAK和HSP90的新角色，并确认c-Cbl抑制在胶质瘤生物学中的重要性，以指导创新治疗的发展。

DESCRIPTION (provided by applicant): Glioblastoma multiforme (GBM) remains the most devastating malignancy of the central nervous system, with little progress having been made over the last several decades in terms of therapeutic development. Characterized by pervasive growth, extensive vascularization and marked chemoresistance, GBM exhibits inevitable recurrence and despite treatment, is associated with only a 14-month survival prognosis. Previous work [13] has identified a novel regulatory pathway (the redox/Fyn/c-Cbl (RFC)) pathway that is present in progenitor cells of the CNS, and appears to be dysregulated in GBM. Inhibiting normal regulation of the E3 ubiquitin ligase c-Cbl perpetuates pro-mitogenic signaling through receptor tyrosine kinases (RTKs), and confers resistance against chemotherapeutic agents. Putative involvement in a multitude of intracellular signaling pathways implicates c-Cbl as a potential convergence point in an integrated network mediating GBM pathology. Preliminary data suggest focal adhesion kinase (FAK) and heat shock protein 90 (HSP90) both are contributors to c-Cbl dysfunction, motivating an investigation into pharmacological inhibition of these compounds as a means of rescuing normal c-Cbl regulation. As such, this proposal aims to test the hypotheses that 1) pharmacological inhibition of FAK restores normal c-Cbl function and enables therapeutically relevant targeting of GBM cells 2) pharmacological inhibition of HSP90 also restores normal c-Cbl activity to enable therapeutical targeting of GBM cells and 3) small molecule inhibitors of FAK and HSP90 restore c-Cbl activity and exhibit therapeutic relevance in a human xenograft mouse model of GBM. Genetic knockdown of c-Cbl and perturbation of the RFC pathway in GBM cells will be combined with analysis of protein interactions, cell viability, RTK degradation, and cancer stem cell phenotype in the presence of pharmacological inhibitors and chemotherapeutics to test the importance of c-Cbl function in these effects. Our overarching goal is to identify novel roles for both FAK and HSP90 and confirm the importance of c-Cbl inhibition in glioma biology to guide development of innovative therapeutics.