ANTI-NEOPLASTIC EFFECTS OF GAMMA-SECRETASE INHIBITORS

γ-分泌酶抑制剂的抗肿瘤作用

• 批准号: 7060670
• 负责人: Lucio Miele
• 金额: $ 22.25万
• 依托单位: UNIVERSITY OF MASSACHUSETTS AMHERST
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7060670
• 关键词: T lymphocyte; acute lymphocytic leukemia; antineoplastics; aspartic endopeptidases; cell line; cell surface receptors; disease /disorder model; drug interactions; immunopharmacology; immunosuppressive; laboratory mouse; neoplasm /cancer chemotherapy; neoplasm /cancer genetics; neoplasm /cancer immunology; neoplasm /cancer immunotherapy; neoplasm /cancer pharmacology; neoplasm /cancer vaccine; neoplastic cell; neuropharmacology; nuclear factor kappa beta; protease inhibitor; serine threonine protein kinase; xenotransplantation

Gamma-Secretase is a multi-subunit membrane protease that catalyzes the regulated cleavage of numerous type I membrane proteins. These include Notch receptors, which require gamma-secretase cleavage for activation. Gamma-Secretase inhibitors have been proposed as therapeutic agents in cancers expressing Notch receptors, particularly T-cell acute lymphoblastic leukemia (T-ALL), where frequent activating Notch-1 mutations have been recently discovered. Our laboratory is exploring pharmacological and genetic strategies to inhibit Notch signaling for the treatment of neoplastic disorders. As a part of this effort, in addition to focusing on cancer cell killing mechanisms, we are exploring potential toxicities and strategies to circumvent them. In collaboration with Drs. Osborne and Golde, we have studied Notch signaling in thymocytes and peripheral T-cells and compared it to what we observe in malignant T-cells from T-ALL and in other cancer cells. Evidence indicates that Notch-1 activates NF-KB in thymocytes, peripheral T-cells, leukemic T-cells, murine erythroleukemia cells (MEL), primary keratinocytes (KC), cervical cancer cells and neurons. These observations suggest that Notch-1 triggers a conserved pathway that activates NF-KB. We have determined that this pathway begins with the gamma-secretase-dependent formation of complexes between cleaved Notch-1 and two key protein kinases: IKK and PI3K, resulting in AKT-mediated IKK and NF-KB activation. This implies that drugs that inhibit Notch activation and drugs that inhibit NF-KB may synergize, and our preliminary data support this hypothesis. We will test this model in pharmacological and mechanistic experiments in T-ALL cells, using gamma-secretase inhibitors in combination with proteasome inhibitors and with glucocorticoids, drugs that prevent NF-KB activation or antagonize its effects respectively. In collaboration with Drs. Kast, Osborne and Golde we have determined that gamma-secretase inhibitors block dendritic cell differentiation and T-cell activation. Therefore, it is possible that systemic administration of these drugs will have immunosuppressive effects and compromise the efficacy of cancer vaccines when used together with them. Therefore, it is important to determine the effects of gamma-secretase inhibitors in established cancer vaccine models and identify the best administration regimens for combined chemo-immunotherapy. To address these issues, we have once again teamed up with Drs. Osborne, Golde and Kast. Our Hypothesis is that gamma-secretase inhibitors such as LY411,575 (LY) will have chemotherapeutic effects in T-ALL cells and other Notch-expressing cancer cells in vitro and in vivo, mainly through inhibition of Notch-mediated activation of NF-KB via the new pathway we discovered. We further hypothesize that proteasome inhibitor bortezomib, which blocks NF-KB activation, and glucocorticoids, which antagonize NF-KB and cause Notch-1 degradation, will synergize with LY in T-ALL cells. We postulate that immunosuppressive effects of LY can be circumvented when used together with cervical cancer vaccines by timing its administration after the priming phase of the immune response. To test our hypothesis, we propose the following Specific Aims: 1. To establish if the in vitro effects and mechanism of action of LY alone and in combination with clinically relevant agents in T-ALL cell lines. Mechanistic studies will focus on AKT and NF-KB. 2. To determine the in vivo effects of LY, alone and in combination with clinically relevant chemotherapeutic agents chosen based on mechanism, on xenograft models of T-ALL. 3. To determine the in vivo effects of LY on the immune response against cancer cells, using well-established models of tumor vaccination.

γ-分泌酶是一种多亚基膜蛋白酶，可催化多种 I 型膜蛋白的受调节裂解。其中包括Notch受体，其需要γ-分泌酶裂解才能激活。 γ-分泌酶抑制剂已被提议作为表达 Notch 受体的癌症的治疗剂，特别是 T 细胞急性淋巴细胞白血病 (T-ALL)，最近发现了频繁的激活 Notch-1 突变。我们的实验室正在探索抑制Notch信号传导以治疗肿瘤疾病的药理学和遗传学策略。作为这项工作的一部分，除了关注癌细胞杀伤机制之外，我们还在探索潜在的毒性和规避它们的策略。与博士合作。 Osborne 和 Golde 博士研究了胸腺细胞和外周 T 细胞中的 Notch 信号传导，并将其与我们在 T-ALL 恶性 T 细胞和其他癌细胞中观察到的信号进行了比较。有证据表明，Notch-1 可激活胸腺细胞、外周 T 细胞、白血病 T 细胞、鼠红白血病细胞 (MEL)、原代角质形成细胞 (KC)、宫颈癌细胞和神经元中的 NF-KB。这些观察结果表明 Notch-1 触发激活 NF-KB 的保守途径。我们已经确定，该途径始于裂解的 Notch-1 和两种关键蛋白激酶 IKK 和 PI3K 之间γ-分泌酶依赖性复合物的形成，从而导致 AKT 介导的 IKK 和 NF-KB 激活。这意味着抑制Notch激活的药物和抑制NF-KB的药物可能具有协同作用，我们的初步数据支持这一假设。我们将在 T-ALL 细胞的药理学和机制实验中测试该模型，使用γ-分泌酶抑制剂与蛋白酶体抑制剂和糖皮质激素（分别阻止 NF-KB 激活或拮抗其作用的药物）组合。与博士合作。 Kast、Osborne 和 Golde 我们已经确定，γ-分泌酶抑制剂可阻断树突状细胞分化和 T 细胞激活。因此，这些药物的全身给药可能会产生免疫抑制作用，并在与它们一起使用时损害癌症疫苗的功效。因此，确定γ-分泌酶抑制剂在已建立的癌症疫苗模型中的作用并确定联合化学免疫疗法的最佳给药方案非常重要。为了解决这些问题，我们再次与博士合作。奥斯本、戈尔德和卡斯特。 我们的假设是，γ-分泌酶抑制剂如 LY411,575 (LY) 将在体外和体内对 T-ALL 细胞和其他表达 Notch 的癌细胞产生化疗作用，主要是通过抑制 Notch 介导的 NF-KB 激活通过我们发现的新途径。我们进一步假设，阻断 NF-KB 激活的蛋白酶体抑制剂硼替佐米和拮抗 NF-KB 并导致 Notch-1 降解的糖皮质激素将与 T-ALL 细胞中的 LY 产生协同作用。我们假设，当 LY 与宫颈癌疫苗一起使用时，通过在免疫反应启动阶段之后进行给药，可以避免 LY 的免疫抑制作用。 为了检验我们的假设，我们提出以下具体目标： 1. 确定 LY 单独使用以及与临床相关药物联合使用在 T-ALL 细胞系中的体外效果和作用机制。机制研究将集中于 AKT 和 NF-KB。 2. 确定 LY 单独使用以及与根据机制选择的临床相关化疗药物联合使用对 T-ALL 异种移植模型的体内作用。 3. 使用完善的肿瘤疫苗接种模型确定 LY 对癌细胞免疫反应的体内影响。