The Role of BCL2 Mediated Calcium Signaling in Leukemia Stem Cell Metabolism

项目总结 本研究的目的是明确控制恶性干细胞存活的分子机制。 急性髓系白血病(AML)细胞。急性髓系白血病(AML)是一种血液系统的恶性肿瘤 由低分化的造血干细胞(25)。传统上，结果一直很差，只有30% 65岁及以上患者对标准护理的应答率(25，26)。耐药和复发的一大原因 治疗的关键是白血病干细胞(LSCs)的持久性(27-30)。LSCs是一群自我更新的细胞 它们能够在免疫受损的动物身上引发和维持疾病(27)。传统化疗 药物不能有效地根除LSCs，开发更有效的治疗方法是一个重大的未完成的任务 需要(27-30)。 约旦实验室以前的工作表明，LSC对氧化具有独特的依赖性 能量产生的磷酸化(OXPHOS)(1-3，24)。此外，bcl2在调节方面具有非规范的作用。 抑制bcl2的LSC代谢导致原代人OXPHOS减少和随后的细胞死亡 LSC(1-3，24)。BCL2抑制剂药物文奈德治疗的AML患者样本分析显示 直接靶向LSC，与70%的应答率相关(3)。因此，该计划的基本前提是 目前的建议是，BCL2介导的对OXPHOS的控制是一个可以利用的关键漏洞 有选择地瞄准LSC。此外，确定OXPHOS如何通过BCL2被抑制具有以下意义 改进急性髓系白血病患者的治疗策略。 这项建议旨在阐明BCL2和LSC OXPHOS之间的机制联系。在几种型号中 系统中，BCL2已被证明在影响钙吸收和释放方面具有非典型作用 内质网和线粒体通过与膜结合的钙通道直接相互作用(7)。细胞内 钙稳态对细胞存活、信号转导和新陈代谢至关重要。特别是，三个速率限制 TCA循环酶、丙酮酸脱氢酶、α-酮戊二酸脱氢酶和异柠檬酸 脱氢酶是钙依赖的反应(7)。因此，BCL2介导了钙离子在细胞间的运动。 内质网和线粒体可能是BCL2和OXPHOS活性之间的机械联系。BCL2调制 根据所研究的细胞类型，内质网和线粒体的钙通道活性不同(7)。 因此，我的建议集中在确定BCL2如何通过调节钙来调节OXPHOS的活性 白血病干细胞中的通道生物学。我的假设是，bcl2介导的钙定位是一种 白血病干细胞中OXPHOS活性的关键调节因子。该提案将决定1)BCL2 介导LSC的钙通道生物学2)钙通道生物调节LSC的代谢和功能 3)调控钙定位是bcl2抑制LSCs的作用机制。

PROJECT SUMMARY The objective of this study is to define the molecular mechanisms that control survival of malignant stem cells in acute myeloid leukemia (AML). Acute myeloid leukemia (AML) is a hematologic malignancy characterized by poorly differentiated hematopoietic stem cells (25). Traditionally, outcomes have been poor with a 30% response rate to standard of care in patients 65 years and older (25,26). A large cause of resistance and relapse to therapy is the persistence of leukemia stem cells (LSCs) (27-30). LSCs are a population of self-renewing cells that are able to initiate and maintain disease in immune-compromised animals (27). Traditional chemotherapy agents do not efficiently eradicate LSCs, and development of more effective therapies is a significant unmet need (27-30). Previous work from the Jordan lab has shown that LSCs have a unique dependence on oxidative phosphorylation (OXPHOS) for energy production (1-3,24). Further, BCL2 has a non-canonical role in regulating LSC metabolism as inhibition of BCL2 led to decreased OXPHOS and subsequent cell death in primary human LSCs (1-3,24). Analysis of samples from AML patients treated with the BCL2 inhibitor drug venetoclax revealed direct targeting of LSCs, which correlated with a 70% response rate (3). Thus, the underlying premise of the current proposal is that BCL2-mediated control of OXPHOS represents a key vulnerability that can be exploited to selectively target LSCs. Further, determining how OXPHOS is inhibited through BCL2 has implications for improving therapeutic strategies for AML patients. This proposal aims to elucidate the mechanistic link between BCL2 and LSC OXPHOS. In several model systems, BCL2 has been shown to have a non-canonical function in influencing calcium uptake and release at the ER and mitochondria through direct interactions with membrane bound calcium channels (7). Intracellular calcium homeostasis is crucial for cell survival, signaling and metabolism. In particular, the three rate limiting enzymes of the TCA cycle, pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and isocitrate dehydrogenase are calcium dependent reactions (7). Therefore, BCL2 mediated calcium movement between the ER and mitochondria could be a mechanistic link between BCL2 and OXPHOS activity. BCL2 modulates the activity of calcium channels at the ER and mitochondria differently, based on the cell type being studied (7). Therefore, my proposal is focused on determining how BCL2 modulates OXPHOS activity by regulating calcium channel biology in leukemia stem cells. My hypothesis is that BCL2 mediated calcium localization is a critical regulator of OXPHOS activity in leukemia stem cells. This proposal will determine whether 1) BCL2 mediates calcium channel biology in LSCs 2) calcium channel biology modulates LSC metabolism/function and 3) regulation of calcium localization is the mechanism of action of BCL2 inhibition in LSCs.