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

描述（由申请人提供）：多形性胶质母细胞瘤（GBM）仍然是中枢神经系统最具破坏性的恶性肿瘤，在过去的几十年里，在治疗发展方面几乎没有取得进展。GBM的特点是广泛生长，广泛血管化和明显的化疗耐药，不可避免地复发，尽管接受治疗，但预后仅为14个月的生存期。先前的工作[13]已经确定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祖细胞中，并且似乎在GBM中失调。抑制E3泛素连接酶c-Cbl的正常调节可通过受体酪氨酸激酶（RTKs）使促有丝分裂信号永续存在，并赋予对化疗药物的抗性。据推测，c-Cbl参与了多种细胞内信号通路，暗示其在介导GBM病理的综合网络中是一个潜在的汇聚点。初步数据表明，局灶黏附激酶（FAK）和热休克蛋白90 （HSP90）都是c-Cbl功能障碍的因素，这促使人们对这些化合物的药理抑制进行研究，以挽救正常的c-Cbl调节。因此，本研究旨在验证以下假设：1)FAK药物抑制恢复正常的c-Cbl功能，使GBM细胞具有治疗相关性；2)HSP90药物抑制也恢复正常的c-Cbl活性，使GBM细胞具有治疗相关性；3)FAK和HSP90小分子抑制剂恢复c-Cbl活性，并在GBM人类异种移植小鼠模型中显示出治疗相关性。在药物抑制剂和化疗药物的作用下，GBM细胞中c-Cbl的基因敲低和RFC通路的干扰将与蛋白质相互作用、细胞活力、RTK降解和癌症干细胞表型的分析相结合，以测试c-Cbl功能在这些作用中的重要性。我们的总体目标是确定FAK和HSP90的新作用，并确认c-Cbl抑制在胶质瘤生物学中的重要性，以指导创新治疗方法的开发。

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.