Oncogenic Nras signaling in leukemic stem cell transformation

摘要 癌基因和抑癌基因突变转化正常造血干细胞 白血病干细胞（LSC）是一个多步骤的过程。作为第一步， 在白血病发生中，“白血病前”突变失调HSC功能，促进克隆形成。 通过增加扩散、竞争力和自我更新来扩张。Pre-LSC还 通过额外的突变转化为LSC。靶向pre-LSC和LSC有可能 来消除白血病尽管许多癌基因和肿瘤抑制基因已经被 提出将正常HSC转化为LSC，关于什么信号传导知之甚少。 这种转变的基础机制允许开发靶向前LSC的疗法 和LSC。我们研究的长期目标是确定信号机制， 癌基因和肿瘤抑制基因将正常HSC转化为LSC。克隆扩增 很难在实验上重现，因为驱动HSC进入循环的突变 通常导致HSC自我更新减少和HSC耗竭。我们最近发现， 在人类白血病中常见的致癌Nras突变，G12 D，使HSC失调， 将其转变为具有更高扩散性、竞争力和自我更新能力的准地方供应链。的 该建议的目的是确定Nras诱导的信号转导机制 转型基于我们的初步结果，我们的中心假设是JAK 2/STAT 5 信号传导在Nras诱导的向前LSC的转化中是关键的，并进一步介导 转化为LSC。我们将通过以下方式检验这一假设：1）确定 NrasG 12 D激活STAT 5以失调HSC功能; 2）定义JAK 2在NrasG 12 D中的作用 诱导的HSC失调和3）确定JAK 2/STAT 5信号传导在完全调节HSC中的作用。 转化的LSC。这种方法是创新的，因为1）它利用了我们新的 发展了克隆扩增模型; 2）它结合了小鼠遗传分析和细胞， 对稀有群体进行生物化学分析，以研究前LSC中的信号传导机制， LSC，和3）它评估了可能负责LSC的非典型Ras效应子的作用。 致癌Ras在与白血病发生高度相关的人群中的作用。拟议 这项研究是重要的，因为它有望提高对信号的认识， 从正常HSC向LSC转化的潜在机制，因此， 新的治疗干预将靶向前LSC和LSC以根除白血病。

ABSTRACT Mutations of oncogenes and tumor suppressor genes transform normal hematopoietic stem cells (HSC) into leukemic stem cells (LSC) in a multi-step process. As the first step of leukemogenesis, the “pre-leukemia” mutations dys-regulate HSC functions to promote clonal expansion by increasing proliferation, competitiveness and self-renewal. Pre-LSCs are further transformed into LSCs by additional mutations. Targeting pre-LSCs and LSCs has the potential to eliminate leukemia. Although many oncogenes and tumor suppressor genes have been proposed to transform normal HSCs to LSCs, very little is known about what signaling mechanism underlies this transformation to allow development of therapies to target pre-LSCs and LSCs. The long term goal of our research is to identify signaling mechanisms through which oncogenes and tumor suppressor genes transform normal HSCs into LSCs. Clonal expansion has been difficult to recapitulate experimentally because mutations that drive HSCs into cycling often lead to reduced HSC self-renewal and HSC depletion. We recently found that an oncogenic Nras mutation commonly found in human leukemias, G12D, dys-regulates HSCs and transform them into pre-LSC with increased proliferation, competitiveness and self-renewal. The objective of this proposal is to identify the signaling mechanism underlying this Nras induced transformation. Based on our preliminary results, our central hypothesis is that JAK2/STAT5 signaling is critical in the Nras induced transformation to pre-LSCs and further mediates transformation to LSCs. We will test this hypothesis by 1) Identify the mechanism by which NrasG12D activates STAT5 to dys-regulate HSC functions; 2) Define the role of JAK2 in NrasG12D induced HSC dys-regulation and 3) determine the role of JAK2/STAT5 signaling in fully transformed LSCs. The approach is innovative because 1) it takes advantage of our newly developed clonal expansion model; 2) it combines mouse genetic analysis and cellular and biochemical analysis on rare populations to investigate signaling mechanisms in pre-LSCs and LSCs, and 3) it evaluates the role of non-canonical Ras effectors that may be responsible for the effects of oncogenic Ras in a population highly relevant to leukemogenesis. The proposed research is significant because it is expected to advance knowledge of the signaling mechanisms underlying the transformation from normal HSCs to LSCs, and therefore to inform novel therapeutic intervention that will target pre-LSCs and LSCs to eradicate leukemia.