Leukemia stem cell regulation and resistance

项目摘要/摘要 慢性粒细胞白血病(CML)是由BCR-1诱导的造血干细胞(HSC)转化而来的 ABL酪氨酸激酶。酪氨酸激酶抑制剂(TKI)在诱导缓解和延长生存方面是有效的 在CML患者中，但无法消除能够再生疾病的原始白血病干细胞(LSC)。多数 患者需要持续的TKI治疗以维持缓解，并仍处于毒性、经济困难和 不遵守。我们研究的长期目标是提高对LSC机制的理解 抵抗治疗，支持制定有效和安全的LSC靶向战略，并加强 慢性粒细胞白血病患者无治疗缓解的可能性。线粒体新陈代谢起着关键的调节作用 在正常的HSC功能中的作用。慢性粒细胞白血病LSC显示线粒体氧化磷酸化增强 (OXPHOS)与正常HSC低OXPHOS的比较。然而，线粒体也扮演着重要的角色 除氧磷外的代谢过程，包括脂肪酸、谷氨酰胺和葡萄糖的氧化，以及 生物合成中间体。我们研究的基本原理是特定的线粒体代谢改变 对LSC生长和TKI抵抗的影响尚不清楚。我们的初步研究表明最初的抑制作用 TKI治疗后CML LSC中OXPHOS的表达，但随后OXPHOS恢复，脂肪酸增加 氧化(粮农组织)，继续治疗。SIRT1、P53和MYC调控网络发挥重要作用 在LSC传播中。我们证明sirt1及其靶基因pgc-1α在体内氧自由基增加中起重要作用。 CML LSC.PPARA是一种PGC-1α共激活的转录因子，也是粮农组织的关键调节因子，它的表达增加 TKI治疗后CML LSC表达增强，有助于OXPHOS的增加、增殖和生存。 我们将探索这样一个假设，即BCR-ABL激酶抑制后粮农组织的增加，以及 维持高水平的OXPHOS、糖酵解和谷氨酰胺分解是CML对TKI耐药的原因 LSC，代谢调节机制是消除经TKI治疗CML的潜在靶点 LSC.在特定目标1中，我们将使用基因表达、细胞外流量、代谢物图谱和 体外和体内代谢标记研究TKI对慢性粒细胞白血病LSC线粒体代谢的影响 检测SIRT1、PGC1a和PPARa在代谢改变中的作用，并研究MYC和P53的相互作用 线粒体新陈代谢的调控网络。在具体目标2中，我们将调查增加的作用 OXPHOS和FAO在促进CML LSC对TKI耐药中的作用骨髓微环境生态位发挥着重要作用 在维持静止的、抗TKI的LSC种群方面发挥关键作用。然而，微环境的作用 LSC在代谢调节方面的生长尚不清楚，将在这里进行评估。这些研究具有重要意义 由于他们有望确定慢性粒细胞白血病LSC中TKI耐药的代谢调节机制， 在CML LSC中建立代谢和其他调节机制之间的联系，并识别新的 治疗的目标。这里提出的概念将对其他恶性肿瘤产生广泛的影响。

PROJECT SUMMARY/ABSTRACT Chronic myelogenous leukemia (CML) results from hematopoietic stem cell (HSC) transformation by the BCR- ABL tyrosine kinase. Tyrosine kinase inhibitors (TKI) are effective in inducing remission and prolonging survival in CML patients, but fail to eliminate primitive leukemia stem cells (LSC) that can regenerate disease. Most patients need ongoing TKI treatment to maintain remission, and remain at risk of toxicity, financial hardship and non-adherence. The long-term goal of our research is to improve understanding of mechanisms of LSC resistance to treatment, to support development of effective and safe strategies for LSC targeting, and enhance possibilities of treatment-free remissions in CML patients. Mitochondrial metabolism plays a critical regulatory role in normal HSC function. CML LSC demonstrate increased mitochondrial oxidative phosphorylation (OXPHOS) compared to low OXPHOS in normal HSC. However, mitochondria also play important roles in metabolic processes besides OXPHOS, including fatty acid, glutamine and glucose oxidation, and generation of biosynthetic intermediates. The rationale for our studies is that specific mitochondrial metabolic alterations that contribute to altered LSC growth and TKI resistance are not known. Our preliminary studies show initial inhibition of OXPHOS in CML LSC after TKI treatment, but subsequent restoration of OXPHOS, and increased fatty acid oxidation (FAO), with continued treatment. A SIRT1, P53 and MYC regulatory network plays an important role in LSC propagation. We show that SIRT1 and its target PGC-1α play an important role in increased OXPHOS in CML LSC. PPARa, a PGC-1α-coactivated transcription factor and a key regulator of FAO, shows increased expression in CML LSC after TKI treatment, and contributes to increased OXPHOS, proliferation and survival. We will explore the hypothesis that increased FAO following BCR-ABL kinase inhibition, together with maintenance of high levels of OXPHOS, glycolysis and glutaminolysis, contributes to TKI resistance in CML LSC, and that metabolic regulatory mechanisms represent potential targets for elimination of TKI-treated CML LSC. In Specific Aim 1 we will use a combination of gene expression, extracellular flux, metabolite profiling and in vitro and in vivo metabolic labeling to study effects of TKI treatment on mitochondrial metabolism in CML LSC, examine the role of SIRT1, PGC1a and PPARa in metabolic alterations, and study interactions of MYC and p53 regulatory networks with mitochondrial metabolism. In Specific Aim 2 we will investigate the role of increased OXPHOS and FAO in promoting TKI resistance in CML LSC. Bone marrow microenvironment niches play a critical role in maintaining quiescent, TKI-resistant LSC populations. However, the role of the microenvironment in metabolic regulation of LSC growth is not known, and will be evaluated here . These studies are significant since they are expected to identify mechanisms of metabolic regulation underlying TKI resistance in CML LSC, establish connections between metabolism and other regulatory mechanisms in CML LSC, and identify new targets for therapy. The concepts developed here will have broad implications for other malignancies.