Molecular and Cellular Regulation of Pre-Leukemic Stem Cells and their Therapeutic Targeting

摘要 在过去的50年里，MDS和AML的临床结局没有显著改善，治愈率仍然很低。 在大多数患者（约85%）中低于15%，年龄>55岁。从根本上说，新的方法是 迫切需要提高我们对疾病发病机制的理解， 干预过去10年的证据表明，MDS和AML起源于白血病前干细胞 在形成完全转化的白血病干细胞（LSC）之前，将前L-SC（preL-SC）转化。最近的工作发现 在MDS和AML中，前L-SC存在相当大的亚克隆异质性，并表明干细胞亚克隆异质性与MDS和AML的预后密切相关。 复杂性在发病机制、进展和治疗抗性中起关键作用。然而，分子 并且控制这些过程的细胞机制在很大程度上仍然未知。转录因子（TF） 长期以来被认为是正常和恶性造血的关键调节剂。具体而言，在MDS和 AML转录失调是赋予细胞发育不良和髓样白血病的特征性特征的关键。 分化阻滞细胞命运和分化决定以及干细胞髓样偏向的诱导 细胞和多能祖细胞水平，这是在前L-SC中检测到的最早的细胞特性之一， 由转录因子控制。此外，我们最近的研究发现， 造血干细胞和祖细胞的转录动力学和可塑性， 可塑性和转录记忆在前L-SC和LSC中失调。我们的主要研究问题/目标 了解干细胞亚克隆动力学及其在MDS发生和进展中的调节， AML，以确定和研究白血病前干细胞及其 治疗靶向，并研究转录动力学和前LSC命运失调，在单细胞和 单分子分辨率。为了实现这些目标，我们将利用干细胞亚克隆分析的新工具 以及新开发的preL-SC进展为MDS的纵向小鼠遗传模型， 急性髓细胞白血病此外，我们将利用我们直接靶向关键转录因子的能力的最新进展， 新型一流的药理学抑制剂，以及用于转录研究的新型实验工具 在来自小鼠模型和患者的原代干/祖细胞中的单分子水平的动力学。总的来说， 我们的研究将描述MDS和AML发病机制中癌前细胞状态的分子调控。 这将使他们的治疗靶向，除了消除完全转化的白血病克隆。 这种方法有望实现MDS和AML的持久缓解和潜在治愈。我们 长期的愿景是，一旦我们了解了癌前病变的早期转化启动机制， 干细胞，甚至有可能在明显的白血病发作之前靶向这种癌前状态， 从而防止变形。

ABSTRACT Clinical outcome in MDS and AML has not significantly improved over the past 50 years and cure rates remain below 15% in the majority of patients (~85%) which are >55 years of age. Fundamentally novel approaches are urgently needed to improve our understanding of disease pathogenesis and to enable more effective therapeutic intervention. Evidence over the past 10 years has shown that MDS and AML arise from preleukemic stem cells (preL-SC), preceding the formation of fully transformed leukemia stem cells (LSC). Recent work has uncovered considerable subclonal heterogeneity of preL-SC in MDS and AML and has indicated that stem cell subclonal complexity plays a key role in pathogenesis, progression, and therapeutic resistance. However, the molecular and cellular mechanisms governing these processes are still largely unknown. Transcription factors (TF) have long been recognized as critical regulators of normal and malignant hematopoiesis. Specifically, in MDS and AML transcriptional dysregulation is key to confer the pathognomonic features of cellular dysplasia and a myeloid differentiation block. Cell fate and differentiation decisions as well as the induction of a myeloid bias at the stem cell and multipotent progenitor level, which is one of the earliest cellular properties detected in preL-SC, are governed by transcription factors. In addition, our recent work has discovered an unexpected degree of transcription dynamics and plasticity in hematopoietic stem and progenitors, and that both transcriptional plasticity and transcriptional memory are dysregulated in preL-SC and LSC. Our major research questions/goals are to understand stem cell subclonal dynamics and their regulation in the initiation and progression of MDS and AML, to identify and study mechanisms of transcriptional cooperativity in pre-leukemic stem cells and their therapeutic targeting, and to study transcription dynamics and pre-LSC fate dysregulation at a single-cell and single-molecule resolution. To accomplish these goals we will utilize novel tools for stem cell subclonal analysis in patients, as well as newly developed longitudinal mouse genetic models of preL-SC progression to MDS and AML. In addition, we will leverage recent advances in our ability to directly target key transcription factors by novel first-in-class pharmacological inhibitors, as well as novel experimental tools for the study of transcription dynamics at a single-molecule level in primary stem/progenitor cells from murine models and patients. Overall, our research will delineate the molecular regulation of pre-cancerous cell states in MDS and AML pathogenesis. This will enable their therapeutic targeting, in addition to the elimination of the fully-transformed leukemic clones. Such an approach holds the promise of achieving lasting remissions and potentially cure of MDS and AML. Our long-term vision is that, once we understand the early transformation-initiating mechanisms in pre-cancerous stem cells, it may even be possible to target such pre-cancerous states before the onset of overt leukemia and thus prevent transformation.