Metabolic Regulation in Leukemia-Initatiating Cells

 描述（由申请人提供）：癌症恶病质是一种复杂的多器官综合征，与厌食和脂肪组织和骨骼肌严重消耗相关，导致许多患者死亡。即使在这种代谢混乱的情况下，癌细胞也在某种程度上免受饥饿的影响，并继续扩张。这就提出了一个基本问题，即癌细胞在恶病质期间如何免受代谢应激的影响。了解这种癌症保护机制可能会导致新的干预措施，以杀死恶病质条件下的癌细胞，从而改善患者的健康。特别是，发展癌症干预措施，使癌细胞对恶病质患者中观察到的营养不良敏感，应该是一个有价值的治疗选择。我们有证据表明，AMPK，感觉能量压力和促进代谢稳态，可能构成这种癌症保护机制。在初步结果中，我们发现MLL-AF 9中AMPK缺失诱导的急性髓细胞性白血病（AML）显著延迟AML的发作，耗尽白血病起始细胞（LIC），并破坏AML细胞的代谢稳态。相反，删除AMPK并不影响正常的造血，这表明白血病细胞比正常造血细胞更依赖AMPK。我们进一步发现AMPK缺陷的AML LIC对体外葡萄糖剥夺特别敏感。引人注目的是，AMPK缺陷型AML的白血病发病延迟通过将受体小鼠置于饮食限制（DR）而进一步延迟，表明体内生理代谢应激使得白血病特别依赖于AMPK。因此，我们假设AMPK是LIC抵抗代谢应激所必需的，并且将AMPK抑制与饮食控制相结合将通过禁用AML的代谢应激反应来抑制AML。我们的长期目标是了解白血病起始细胞如何利用代谢调节剂在癌症患者常见的营养不良条件下生存。在目标1中，我们将通过进行代谢通量分析和定量AML细胞中的各种代谢物来确定AMPK如何促进AML细胞的代谢稳态。在目标2中，我们将确定AMPK抑制和饮食控制如何协同抑制白血病发生。在目标3中，我们将通过删除和/或抑制Glut 1来验证我们的假设，即Glut 1是AMPK控制的白血病发生的关键调节因子。我们还将删除其他调节葡萄糖代谢的候选代谢酶，并检查它们在白血病发生中的功能，并赋予AML细胞代谢应激抗性。完成本课题后，我们将对AMPK通路在代谢应激下维持白血病起始细胞中的作用有更深入的了解。由于AMPK不是正常造血所必需的，因此我们的研究中显示的AMPK抑制与饮食控制相结合可能提供一种新的抗白血病疗法，其靶向白血病而不损害正常HSC和造血。

 DESCRIPTION (provided by applicant): Cancer cachexia is a complex multi-organ syndrome associated with anorexia and severe wasting of adipose tissue and skeletal muscle, contributing to the mortality of many patients. Even under this metabolic mayhem, cancer cells are somewhat protected from starvation and continue to expand. This raises a fundamental question of how cancer cells are protected from metabolic stress during cachexia. Understanding this cancer protective mechanism may lead to novel intervention to kill cancer cells under cachectic conditions, thereby improving patients' health. Particularly, development of cancer interventions rendering cancer cells sensitive to malnutrition observed in cachectic patients should be a valuable therapeutic option. We have evidence to suggest that AMPK, which senses energy stress and promotes metabolic homeostasis, may constitute this cancer protective mechanism. In preliminary results, we found that AMPK deletion from MLL-AF9 induced acute myelogenous leukemia (AML) significantly delayed the onset of AML, depleted leukemia-initiating cells (LICs), and disrupted metabolic homeostasis of AML cells. In contrast, deleting AMPK did not affect normal hematopoiesis, demonstrating that leukemic cells are more dependent on AMPK than normal hematopoietic cells. We further found that AMPK-deficient AML LICs are particularly sensitive to glucose deprivation in vitro. Strikingly, the delayed onset of leukemogenesis by AMPK-deficient AML was further delayed by placing the recipient mice on dietary restriction (DR), indicating that physiological metabolic stress in vivo renders leukemia particularly dependent on AMPK. We thus hypothesized that AMPK is required for LICs to resist metabolic stress, and that combining AMPK inhibition with dietary manipulation will suppress AML by disabling the metabolic stress response of AML. Our long-term goal is to understand how leukemia-initiating cells utilize metabolic regulators to survive malnourished conditions often found in cancer patients. In aim 1, we will determine how AMPK promotes the metabolic homeostasis of AML cells, by performing metabolic flux analysis and quantifying various metabolites in AML cells. In aim 2, we will determine how AMPK inhibition and dietary manipulation synergize to suppress leukemogenesis. In aim 3, we will test our hypothesis that Glut1 is a critical regulator of leukemogenesis controlled by AMPK, by deleting and/or inhibiting Glut1. We will also delete other candidate metabolic enzymes that regulate glucose metabolism and examine their function in leukemogenesis and conferring metabolic stress resistance to AML cells. Upon completion of this proposal, we will have deep understanding of the role of AMPK pathway in maintaining leukemia-initiating cells under metabolic stress. Since AMPK is not required for normal hematopoiesis, AMPK inhibition combined with dietary control shown in our study may offer a novel anti-leukemia therapy that targets leukemia without impairing normal HSCs and hematopoiesis.