Investigating Alpha-secretase inhibitors as Notch inhibitors & anti-glioma agents

研究α-分泌酶抑制剂作为Notch抑制剂

• 批准号: 7683079
• 负责人: Benjamin W. Purow
• 金额: $ 27万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7683079
• 关键词: Address; Affect; Brain Neoplasms; Cannulas; Cell Line; Cell Maintenance; Cell Survival; Cell model; Cells; Classification; Cleaved cell; Clinical; Data; Development; Erinaceidae; FBXW7 gene; Flow Cytometry; Glioma; Gliomagenesis; Human; Immunoblotting; Immunohistochemistry; In Vitro; Injection of therapeutic agent; Investigation; Length; Ligands; Light; Luciferases; Malignant Neoplasms; Mus; Output; Pathway interactions; Patients; Phenotype; Plasmids; Positioning Attribute; Process; Proteins; Pump; Radiation; Radiation therapy; Radiosensitization; Reporter; Reporting; Resistance; Role; Secondary to; Stem cells; Testing; Therapeutic; Time; Transfection; Tumor Stem Cells; Work; Xenograft Model; Xenograft procedure; alpha secretase; cancer type; cell growth; chemotherapy; clinical application; cranium; established cell line; experience; follow-up; gamma secretase; in vivo; inhibitor/antagonist; leukemia; new therapeutic target; notch protein; novel; pre-clinical; public health relevance; research study; restoration; secretase; standard care; stem cell differentiation; stem cell population; therapeutic target; therapy resistant; treatment effect; tumor; tumor growth; tumorigenesis; ubiquitin ligase

DESCRIPTION (provided by applicant): Despite notable advances in treating other cancers during the last two decades, brain tumors remain a daunting therapeutic challenge. These tumors are highly resistant to standard treatment with radiation and chemotherapy, and this has driven an urgent search for novel therapeutic targets in high-grade gliomas. We previously showed the Notch pathway, key in stem cell maintenance and cell fate determination, to be one such target. Notch-1 and its ligands are over-expressed and active in gliomas, and blocking their expression is lethal in human glioma cells. Notch inhibition may be especially promising because of its prominent role in stem cells. Recent evidence from us and others indicates that gliomas and other cancers harbor a small therapy-resistant subpopulation of tumor stem cells responsible for tumorigenesis. The resistance of these glioma tumor stem cells to standard therapies makes it critical to find other means to target them. Early evidence suggests that blockade of pathways essential in normal stem cells, such as Hedgehog, Wnt, and Notch, may have therapeutic utility against tumor stem cells. The only Notch inhibitors reported to date are the gamma-secretase inhibitors (GSIs), which block an enzymatic cleavage necessary for Notch processing. However, Notch is also cleaved by an alpha-secretase prior to its cleavage by gamma-secretase, suggesting another vulnerable point in the pathway. Our preliminary data indicate for the first time that alpha-secretase inhibitors (ASIs) block Notch activity and also inhibit the viability of glioma tumor stem cells. In this application, we propose the systematic investigation of ASIs as an unexplored class of Notch inhibitors with activity against glioma cells, including glioma tumor stem cells (GTSCs). In Aim #1, we compare specific and non-specific ASIs with GSIs as Notch inhibitors and also assess them in combination. In addition, we determine if levels of the ubiquitin ligase FBXW7, which degrades Notch, affect sensitivity of glioma cells to Notch inhibition by secretase inhibitors. To further investigate ASIs as potential anti-glioma therapies, we determine in aim #2 the effects of ASIs on other pathways central in gliomagenesis. In Aim #3, we compare ASIs and GSIs for their effects on GTSC viability and differentiation and evaluate if restoration of Notch activity can rescue the phenotype. We assess local delivery of an ASI and GSI as therapies in mouse intracranial GTSC models in Aim #4, alone and in combination with radiotherapy. Additionally, a glioma line with luciferase expressed under Notch control will be used to track Notch activity real-time in vivo with local delivery of Notch inhibitors. Successful completion of the proposed experiments will validate ASIs as a novel class of Notch inhibitors and characterize their effects on gliomas and GTSCs. This work will establish these agents as potential therapies in patients with gliomas, with implications for other cancer types as well. PUBLIC HEALTH RELEVANCE: Gliomas are the most common and most lethal brain tumors. They are highly resistant to standard chemotherapy and radiation, and recent work by us and others suggests that this could in part be due to the presence of a subpopulation of therapy-resistant "glioma tumor stem cells" (GTSCs). We previously identified the Notch pathway as a promising therapeutic target in gliomas. Targeting stem cell pathways such as Notch may be a means to inhibit the tumor stem cell population. In this proposal we will investigate alpha-secretase inhibitors as a novel class of Notch inhibitors with therapeutic activity against glioma tumor stem cells.

描述（由申请人提供）：尽管在过去二十年中在治疗其他癌症方面取得了显著进展，但脑肿瘤仍然是一个令人生畏的治疗挑战。这些肿瘤对放疗和化疗的标准治疗具有高度抗性，这促使人们迫切寻找高级别胶质瘤的新治疗靶点。我们之前已经证明了Notch通路是干细胞维持和细胞命运决定的关键，是这样一个靶点。Notch-1及其配体在神经胶质瘤中过度表达并具有活性，阻断它们的表达在人神经胶质瘤细胞中是致命的。Notch抑制可能特别有希望，因为它在干细胞中的突出作用。我们和其他人最近的证据表明，胶质瘤和其他癌症含有一个小的肿瘤干细胞治疗耐药亚群负责肿瘤发生。这些神经胶质瘤肿瘤干细胞对标准疗法的抗性使得找到其他靶向它们的方法变得至关重要。早期证据表明，阻断正常干细胞中必需的途径，如Hedgehog、Wnt和Notch，可能对肿瘤干细胞具有治疗效用。迄今为止报道的唯一Notch抑制剂是γ-分泌酶抑制剂（GSI），其阻断Notch加工所必需的酶促裂解。然而，Notch在被γ-分泌酶切割之前也被α-分泌酶切割，这表明该途径中的另一个脆弱点。我们的初步数据首次表明，α-分泌酶抑制剂（ASI）阻断Notch活性，并抑制胶质瘤肿瘤干细胞的活力。在本申请中，我们提出了系统研究ASI作为一类未开发的Notch抑制剂，具有抗神经胶质瘤细胞（包括神经胶质瘤肿瘤干细胞（GTSC））的活性。在目标#1中，我们比较了特异性和非特异性ASI与GSI作为Notch抑制剂，并对它们进行了联合评估。此外，我们确定降解Notch的泛素连接酶FBXW 7的水平是否影响神经胶质瘤细胞对分泌酶抑制剂抑制Notch的敏感性。为了进一步研究ASI作为潜在的抗神经胶质瘤疗法，我们在目标#2中确定ASI对神经胶质瘤形成中的其他途径的影响。在目标#3中，我们比较了ASI和GSI对GTSC活力和分化的影响，并评估了Notch活性的恢复是否可以挽救表型。我们评估了ASI和GSI的局部递送作为目标#4中的小鼠颅内GTSC模型中的治疗，单独和与放射疗法组合。此外，具有在Notch控制下表达的荧光素酶的神经胶质瘤系将用于在体内实时追踪Notch活性，局部递送Notch抑制剂。成功完成所提出的实验将验证ASI作为一类新型Notch抑制剂，并表征其对胶质瘤和GTSCs的作用。这项工作将确立这些药物作为神经胶质瘤患者的潜在疗法，对其他癌症类型也有影响。公共卫生相关性：神经胶质瘤是最常见和最致命的脑肿瘤。它们对标准化疗和放疗具有高度抗性，我们和其他人最近的工作表明，这可能部分是由于存在治疗抗性的“胶质瘤肿瘤干细胞”（GTSCs）亚群。我们以前确定Notch通路作为胶质瘤的一个有前途的治疗靶点。靶向干细胞途径如Notch可能是抑制肿瘤干细胞群的一种手段。在这个提议中，我们将研究α-分泌酶抑制剂作为一类新的Notch抑制剂，对神经胶质瘤肿瘤干细胞具有治疗活性。