Targeting the Metabolic Regulator SIRT5 in Acute Myeloid Leukemia

靶向急性髓系白血病的代谢调节因子 SIRT5

• 批准号: 10523086
• 负责人: Michael W. Deininger
• 金额: $ 32.47万
• 依托单位: VERSITI WISCONSIN, INC.
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10523086
• 关键词: Targeting; Metabolic; Regulator; SIRT5; Acute

PROJECT SUMMARY TARGETING THE METABOLIC REGULATOR SIRT5 IN ACUTE MYELOID LEUKEMIA. AML is an aggressive hematologic malignancy with <30% long-term survival. The current therapy standard, chemotherapy alone or combined with allogeneic stem cell transplant, has not changed for decades. Despite initial responses, most patients eventually relapse, suggesting persistence of leukemia initiating cells in protective niches. Inhibitors of FLT3 or mutant isocitrate dehydrogenase 1/2 (IDH1/2) have expanded therapy options and validated the paradigm of genotype-directed therapy. However, even with these new drugs, relapse is common and frequently due to selection of subclones with resistance mutations in the drug target. Unlike FLT3 and IDH1/2 inhibitors, the BCL2 inhibitor venetoclax is active in multiple AML genotypes, indicating that targeting shared vulnerabilities in a genotype-agnostic manner can be effective. Unfortunately many venetoclax-induced responses are not durable as leukemia cells adapt by activating alternative anti-apoptosis mechanisms or by reprogramming mitochondrial metabolism. Microenvironmental protection, intra-tumoral heterogeneity and metabolic flexibility limit the utility of current AML therapies. To identify new therapy targets in AML, we adapted an shRNA screen for testing primary AML cells under bone marrow microenvironment-like conditions. We discovered that many AML patient samples are highly dependent on SIRT5, while normal CD34+ cells are not. SIRT5 is a lysine deacylase implicated in the regulation of energy metabolic pathways, including oxidative phosphorylation (OXPHOS), fatty acid β-oxidation and glycolysis. SIRT5 knockdown (KD) reduces growth and increases apoptosis in most AML cell lines, with consistent results upon disruption of SIRT5 using CRISPR/Cas9 or NRD167, a novel cell-permeable SIRT5 inhibitor. Genetic absence of Sirt5 impairs in vitro transformation of mouse hematopoietic cells by several myeloid oncogenes, including MLL-AF9, and attenuates leukemogenesis in vivo. At a biochemical level, SIRT5 KD or inhibition with NRD167 is associated with reduced OXPHOS, reduced glutathione levels and increased mitochondrial superoxide, suggesting that AML cells depend on SIRT5 to maintain redox homeostasis. Sirt5-/- mice are viable with minor metabolic abnormalities, suggesting that in vivo inhibition of SIRT5 would be tolerated. We hypothesize that SIRT5 is a therapy target in AML and will test this in three Specific Aims: (1) Identify and validate SIRT5-regulated metabolic pathways in normal and AML stem and progenitor cells. (2) Identify biomarkers of sensitivity to SIRT5 inhibition in primary AML cells. (3) Identify a potent, selective, and bioavailable SIRT5 inhibitor, starting from the NRD167 tool compound. Our work will rigorously test whether SIRT5 is a therapy target in AML, clarify the mechanisms underlying SIRT5 dependence, and identify potent and selective SIRT5 inhibitors for future clinical development.

项目概要 针对急性髓系白血病的代谢调节因子 SIRT5 是一种积极的治疗方法。 长期生存率<30%的血液恶性肿瘤目前的治疗标准是单独化疗或化疗。 与同种异体干细胞移植相结合，尽管有最初的反应，但几十年来一直没有改变。 患者最终会复发，这表明白血病起始细胞在保护性微环境抑制剂中持续存在。 FLT3 或突变异柠檬酸脱氢酶 1/2 (IDH1/2) 扩大了治疗选择并验证了 然而，即使使用这些新药，复发也很常见且频繁。 与 FLT3 和 IDH1/2 抑制剂不同，由于选择了药物靶标中具有耐药突变的亚克隆， BCL2 抑制剂 Venetoclax 在多种 AML 基因型中具有活性，表明针对共同的漏洞 不幸的是，许多维奈托克诱导的反应并不有效。 由于白血病细胞通过激活替代抗凋亡机制或通过重新编程来适应，因此具有持久性 线粒体代谢。微环境保护、肿瘤内异质性和代谢灵活性。 限制当前 AML 疗法的效用 为了确定 AML 的新治疗靶点，我们采用了 shRNA 筛选。 我们发现，在类似骨髓微环境的条件下测试原代 AML 细胞。 AML 患者样本高度依赖 SIRT5，而正常 CD34+ 细胞则不是赖氨酸。 脱酰酶参与能量代谢途径的调节，包括氧化磷酸化 (OXPHOS)、脂肪酸 β-氧化和糖酵解 (KD) 会降低生长并增加。 大多数 AML 细胞系中的细胞凋亡，使用 CRISPR/Cas9 或 NRD167，一种新型细胞渗透性 SIRT5 抑制剂，Sirt5 的遗传缺失会损害体外转化。 包括 MLL-AF9 在内的多种髓系癌基因对小鼠造血细胞产生影响，并减弱白血病的发生 在体内生化水平上，SIRT5 KD 或 NRD167 的抑制与 OXPHOS 的减少有关。 谷胱甘肽水平降低和线粒体超氧化物增加，表明 AML 细胞依赖 SIRT5 Sirt5-/- 小鼠可在轻微代谢异常的情况下维持氧化还原稳态。 SIRT5 的体内抑制是可以耐受的，我们认为 SIRT5 是 AML 的治疗靶标，并将进行测试。 这有三个具体目标：(1) 识别并验证正常和正常人群中 SIRT5 调节的代谢途径。 AML 干细胞和祖细胞 (2) 鉴定原发性 AML 中对 SIRT5 抑制敏感的生物标志物。 (3) 从 NRD167 工具开始，鉴定一种有效的、选择性的、生物可利用的 SIRT5 抑制剂。 我们的工作将严格测试 SIRT5 是否是 AML 的治疗靶点，阐明其机制。 潜在的 SIRT5 依赖性，并为未来的临床开发确定有效和选择性的 SIRT5 抑制剂。