Targeting leukemic stem cells in acute myeloid leukemia

项目摘要 急性髓系白血病(AML)是一种克隆性血液系统恶性肿瘤，治疗选择有限。它 起源于并维持于一小部分自我更新的前体细胞--白血病启动/干细胞 细胞(LSC)。这种不朽的肿瘤细胞库表现出极低的增殖率和对 目前的治疗方法。他们也要对复发负责。它仍然是一个关键的挑战，以制定有效的 根除LSCs的治疗。一种新的方法，专注于 为了解决这个问题，需要LSC。我们之前发现了一种生物能量应激诱导的 造血干细胞(HSCs)分化/再繁殖检查点在研究PTPMT1中的作用 基于磷脂酰肌醇的磷酸酶。PTPMT1基因敲除降低线粒体代谢并导致 生物能量应激，进而触发细胞周期检查点(AMPK-p21/p57)，导致分化- 与造血干细胞相关的细胞周期停滞。重要的是，这些敲除的造血干细胞的存活和自我更新不是 受影响，其分化障碍是可逆的。我们最近的初步研究表明，类似的 生物能应激诱导的细胞周期检查点也可能在LSCs中发挥作用-发育和 癌基因(Flt3-ITD和MLL-AF9)驱动的维持或PTEN缺失诱导的AML基本上是 被PTPMT1的缺失所抑制。有趣的是，PTPMT1的缺失诱导了LSCs的细胞死亡 与HSCs形成对比。从机制上讲，PTPMT1缺失并不影响线粒体结构；相反，它似乎 阻断线粒体对主要代谢底物丙酮酸的利用，丙酮酸是葡萄糖的关键代谢物 这是线粒体氧化和胞质发酵的交汇点。基于这些观察， 我们假设LSCs可以通过诱导生物能量/代谢应激和细胞周期停滞而成为靶点。 通过药物抑制PTPMT1或线粒体摄取丙酮酸，这可能产生 根除LSCs。值得注意的是，阿利西定二盐酸盐，一种用作防腐和抗菌斑的抗生素 用于牙科产品的药物，已被确定为一种选择性和有效的PTPMT1抑制剂，罗格列酮 (文迪雅)，一种有效的抗2型糖尿病药物(以前称为过氧化物酶体增殖物激活受体γ 激动剂)，已被证明有效地抑制线粒体丙酮酸载体/转运体(MPC)。结果, 这些药物的新特性将成为检验我们假设的关键资产。我们计划实现 这项建议的目标是通过追求以下三个目标。1)。为了进一步描述 LSC上的PTPMT1耗尽。2)。确定PTPMT1耗竭抑制的分子机制 线粒体代谢。3)。检测PTPMT1抑制剂阿利西定的潜在疗效 盐酸二氢叶酸和MPC抑制剂罗格列酮在人AML异种移植模型中的应用这个项目，如果 成功，可能导致一种新的策略来耗尽AML中的LSCs，并且PTPMT1和MPC抑制剂可能是 被重新用于并进一步发展为急性髓系白血病的治疗剂。

Project Summary Acute myeloid leukemia (AML) is a clonal hematological malignancy with limited therapeutic options. It originates from and is sustained by a small population of self-renewing precursor cells - leukemia initiating/stem cells (LSCs). This immortal reservoir of tumor cells displays extremely low proliferation rates and resistance to current treatments. They are also responsible for relapses. It remains a critical challenge to develop effective therapeutics to eradicate LSCs. A novel approach focused on the unique characteristics and vulnerabilities of LSCs is needed in order to address this problem. We previously discovered a bioenergetic stress-induced differentiation/repopulation checkpoint in hematopoietic stem cells (HSCs) in studying PTPMT1, a mitochondria- based phosphoinositide phosphatase. Knockout of PTPMT1 decreases mitochondrial metabolism and causes bioenergetic stress, which in turn triggers a cell cycle checkpoint (AMPK-p21/p57), leading to differentiation- associated cell cycle arrest in HSCs. Importantly, the survival and self-renewal of these knockout HSCs are not affected, and their differentiation block is reversible. Our recent preliminary study suggests that a similar bioenergetic stress-induced cell cycle checkpoint may also operate in LSCs --- the development and maintenance of oncogene (FLT3-ITD and MLL-AF9)-driven or PTEN loss-induced AML are substantially inhibited by the deletion of PTPMT1. Interestingly, PTPMT1 depletion induces cell death in LSCs, in sharp contrast to HSCs. Mechanistically, PTPMT1 loss does not impact mitochondrial structure; rather, it appears to block mitochondrial utilization of the major metabolic substrate pyruvate, a key metabolite derived from glucose that lies at the intersection of mitochondrial oxidation and cytosolic fermentation. Based on these observations, we hypothesize that LSCs can be targeted by inducing bioenergetic/metabolic stress and cell cycle arrest through pharmacological inhibition of PTPMT1 or mitochondrial uptake of pyruvate, which yields the possibility of eradicating LSCs. Notably, alexidine dihydrochloride, an antibiotic used as an anti-septic and anti-plaque agent for dental products, has been identified as a selective and potent PTPMT1 inhibitor, and rosiglitazone (Avandia), a viable anti-type 2 diabetic drug (previously known as a peroxisome proliferator-activated receptor γ agonist), has been shown to effectively inhibit the mitochondrial pyruvate carrier/transporter (MPC). As a result, the novel properties of these drugs will serve as a critical asset for testing our hypothesis. We plan to achieve the objective of this proposal by pursuing the following three aims. 1). To further characterize the effects of PTPMT1 depletion on LSCs. 2). To determine the molecular mechanisms by which PTPMT1 depletion inhibits mitochondrial metabolism. 3). To test for the potential therapeutic effects of the PTPMT1 inhibitor alexidine dihydrochloride and the MPC inhibitor rosiglitazone in xenograft models of human AML. This project, if successful, may lead to a novel strategy to deplete LSCs in AML, and the PTPMT1 and MPC inhibitors could be repurposed and further developed into therapeutic agents for AML.