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

摘要 MDS和AML的临床结果在过去50年中没有显著改善，治愈率仍然存在 在大多数(~85%)55岁的患者中低于15%。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，并使更有效的治疗 干预。过去10年的证据表明，MDS和AML起源于白血病前期干细胞 (preL-SC)，在形成完全转化的白血病干细胞(LSC)之前。最近的研究发现 MDS和AML中preL-SC的亚克隆异质性较大，并提示干细胞亚克隆 复杂性在发病机制、进展和治疗耐药中起着关键作用。然而，分子 控制这些过程的细胞机制在很大程度上仍不清楚。转录因子(Tf)有 长期以来一直被认为是正常和恶性造血的关键调节因子。具体而言，在MDS和 AML转录异常是导致细胞异型增生和髓样病变的关键 分化障碍。细胞命运和分化决定以及干细胞髓系偏向的诱导 细胞和多能祖细胞水平，这是在preL-SC中检测到的最早的细胞特性之一， 受转录因子控制。此外，我们最近的工作发现了意想不到的程度 造血干和祖细胞的转录动力学和可塑性，以及两者转录 在preL-SC和LSC中，可塑性和转录记忆功能失调。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和MDS发生发展中的调节作用 急性髓系白血病，鉴定和研究白血病前干细胞转录协同作用的机制。 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，我们将利用新的工具进行干细胞亚克隆分析。 以及新开发的前L-SC进展为MDS和MDS的纵向小鼠遗传模型。 AML。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，通过 新的一流药物抑制剂，以及用于转录研究的新的实验工具 来自小鼠模型和患者的初级干细胞/祖细胞单分子水平的动力学。总的来说， 我们的研究将阐明MDS和AML发病机制中癌前细胞状态的分子调控。 这将使他们能够治疗靶向，除了消除完全转化的白血病克隆。 这样的方法有望实现持久的缓解，并有可能治愈MDS和AML。我们的 长远的愿景是，一旦我们了解了癌前病变早期转化的启动机制 干细胞，甚至有可能在显性白血病发作之前针对这种癌前状态和 从而阻止变形。

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.