Regulation of Protein Synthesis in Leukemia Stem Cells

摘要/摘要 白血病干细胞(LSCs)促进急性髓系白血病的治疗耐药和不良临床结局 白血病(AML)。LSCs功能的核心是异常自我更新的能力，但其机制 这一活动背后的原因还没有得到很好的理解。长期目标是确定要开发的这些机制 可以根除LSCs以改善临床结果的新疗法。本应用程序的总体目标 目的是(I)确定来自特定基因亚型AML的LSCs是否依赖于蛋白质的调节 合成，(Ii)确定高危造血干细胞样AML中的LSCs是否更依赖于 关于调节蛋白质合成，以及(Iii)测试一种抑制LSC蛋白质合成的新治疗策略。这个 中心假说是LSCs通过从正常的HSCs中接受一种紧密依赖的方式而异常地自我更新 调节蛋白质合成。这个项目的基本原理是基于细胞表面标记的发现 CD99在LSC上选择性过表达，调节蛋白质合成，促进LSC功能。 这为制定消耗LSC的新战略提供了强有力的科学框架。中环 假说将通过追求三个具体目标来检验：1)确定蛋白质合成受调控的作用 在促进LSC功能方面；2)确定AML的起源细胞是否影响LSCs对 调节蛋白质合成；以及3)确定抑制蛋白质合成是否会耗尽高危患者的LSCs AML。在第一个目标中，基因工程小鼠将被用来产生缺乏CD99的AML模型，以进行测试 如果这导致蛋白质合成失调，从而损害LSC的自我更新。这些型号的LSC将 评估以确定它们是否需要较低的蛋白质合成率来防止诱导肿瘤抑制基因， 未折叠的蛋白质反应，以及整合的应激反应。将进行核糖体分析以确定 关键的LSC调节器选择性地在受调控的蛋白质合成的背景下翻译。在第二个目标中，我们将 建立类似HSC的AML小鼠模型，模拟高危人类AML。我们将评估HSC中的LSC- 像急性髓系白血病一样，对蛋白质合成失调表现出高度的敏感性。这些研究将得到补充 通过评估类HSC的蛋白质合成来确定它们是否也需要维持 低水平的蛋白质合成。第三个目标将测试核糖体生物发生抑制剂与 目前用于治疗AML的bcl2抑制剂可以根除高危HSC样AML中的LSCs。该提案是 申请人认为，这是一种创新，因为它的目标是利用一种新的LSC特有的细胞表面标记来 建立一个新的范式来理解LSC自我更新的潜在机制。拟议的研究 具有重要意义，因为它有望为治疗方法的发展提供强有力的科学依据 抑制蛋白质合成以克服高危AML患者的治疗阻力。归根结底， 从这些研究中获得的知识可能会对促进癌症功能的机制提供洞察力 干细胞，为开发治疗癌症的新策略打开了机会。

Summary/Abstract Leukemia stem cells (LSCs) promote therapeutic resistance and poor clinical outcomes in acute myeloid leukemia (AML). Central to the function of LSCs is a capacity for aberrant self-renewal, but the mechanisms underlying this activity are not well understood. The long-term goal is to identify these mechanisms to develop new therapies that can eradicate LSCs to improve clinical outcomes. The overall objectives in this application are to (i) determine if LSCs from specific genetic subtypes of AML are dependent on regulation of protein synthesis, (ii) determine whether LSCs in high-risk hematopoietic stem cell (HSC)-like AMLs are more dependent on regulated protein synthesis, and (iii) test a novel therapeutic strategy inhibiting protein synthesis in LSCs. The central hypothesis is that LSCs aberrantly self-renew by adopting from normal HSCs a dependence on tightly regulated protein synthesis. The rationale for this project is based on the finding that the cell surface marker CD99 is selectively overexpressed on LSCs and serves to regulate protein synthesis to promote LSC function. This offers a strong scientific framework by which new strategies to deplete LSCs can be developed. The central hypothesis will be tested by pursuing three specific aims: 1) Determining the role of regulated protein synthesis in promoting LSC function; 2) Determining if the cell-of-origin of AML influences the dependence of LSCs on regulated protein synthesis; and 3) Determining if inhibition of protein synthesis can deplete LSCs in high-risk AML. In the first aim, genetically engineered mice will be used to generate models of AML lacking CD99, to test if this leads to dysregulated protein synthesis that impairs LSC self-renewal. LSCs from these models will be evaluated to determine if they require low protein synthesis rates to prevent induction of tumor suppressors, the unfolded protein response, and the integrated stress response. Ribosome profiling will be performed to identify key LSC regulators selectively translated in the context of regulated protein synthesis. In the second aim, we will generate a mouse model of HSC-like AML which mimics high-risk human AML. We will assess if LSCs in HSC- like AML exhibit heightened sensitivity to dysregulated protein synthesis. These studies will be complemented with an evaluation of protein synthesis in HSC-like human LSCs to determine if they also require maintenance of low levels of protein synthesis. The third aim will test if the combination of a ribosome biogenesis-inhibitor with a BCL2-inhibitor currently used to treat AML can eradicate LSCs in high-risk HSC-like AML. The proposal is innovative, in the applicant’s opinion, because it aims to leverage a novel LSC-specific cell surface marker to establish a new paradigm for understanding mechanisms underlying LSC self-renewal. The proposed research is significant because it is expected to provide a strong scientific justification for the development of therapies inhibiting protein synthesis to overcome therapeutic resistance in patients with high-risk AML. Ultimately, the knowledge gained from these studies may offer insights into the mechanisms that promote the function of cancer stem cells in general, opening up opportunities for the development of new strategies to treat cancer.