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 细胞(HSC)在多步骤的过程中转化为白血病干细胞(LSC)。作为……的第一步 白血病发生，“白血病前”突变异常调节HSC功能促进克隆性 通过增加扩散、竞争力和自我更新进行扩张。LSC预科课程还包括 通过额外的突变转化为LSCs。瞄准前LSC和LSC具有潜在的 以消除白血病。尽管许多癌基因和抑癌基因已经被 有人建议将正常的HSCs转化为LSCs，但对哪些信号转导机制知之甚少 这一转变的基础是机制，以允许开发针对LSCs前驱的治疗方法 和LSC。我们研究的长期目标是确定信号机制，通过 癌基因和肿瘤抑制基因将正常的HSCs转化为LSCs。克隆扩增 很难在实验中概括，因为驱动HSCs进入循环的突变 通常会导致HSC自我更新减少和HSC耗尽。我们最近发现，一个 在人类白血病中常见的致癌NRAS突变G12D，异常调节HSCs和 将它们转变为具有更强的扩散性、竞争力和自我更新的Pre-LSC。这个 这项建议的目的是确定NRAS诱导的信号机制 转型。根据我们的初步结果，我们的中心假设是JAK2/STAT5 信号转导在NRAS诱导的前LSCs转化过程中起关键作用 向LSC转型。我们将通过以下方法来检验这一假设：1)确定 NrasG12D激活STAT5对HSC功能进行动态调节；2)确定JAK2在NrasG12D中的作用 3)确定JAK2/STAT5信号在FULL中的作用 转换后的LSC。这种方法是创新的，因为1)它利用了我们新的 建立了克隆扩增模型；2)结合了小鼠遗传分析和细胞和 对稀有种群进行生化分析以研究前LSCs和LSCs的信号机制 LSC，以及3)它评估非规范RAS效应器的作用 致癌RAS在与白血病发生高度相关的人群中的作用。建议数 这项研究意义重大，因为它有望促进对信号转导的了解 从正常HSC向LSCs转化的潜在机制，并因此告知 针对前LSCs和LSCs的新型治疗干预措施，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.