CLONAL DOMINANCE OF HEMATOPOIETIC STEM CELLS EXPRESSING MUTANT CSF3R

表达突变体 CSF3R 的造血干细胞的克隆优势

• 批准号: 7714411
• 负责人: Daniel C Link
• 金额: $ 31.54万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-05-01 至 2014-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7714411
• 关键词: Acute Myelocytic Leukemia; Adhesions; Biological; Blood Cells; Bone Marrow; CD34 gene; CSF3 gene; CSF3R gene; Candidate Disease Gene; Cell Proliferation; Cell physiology; Cells; Clonal Expansion; Clonal Hematopoietic Stem Cell; Cytoskeleton; Data; Defect; Dysmyelopoietic Syndromes; Embryo; Engraftment; Epigenetic Process; Event; Genes; Genetic Transcription; Goals; Granulocyte Colony-Stimulating Factor Receptors; Granulopoiesis; Hematopoietic; Hematopoietic stem cells; Individual; Knock-in Mouse; Lead; Leukemic Cell; Mediating; Modeling; Molecular; Molecular Profiling; Mus; Mutate; Mutation; Neutropenia; Pancytopenia; Pathway interactions; Patients; Phenylalanine; Physiological; Property; Receptor Cell; Regulation; Research; Resistance; Risk; Role; STAT5A gene; Signal Transduction; Stem cells; Syndrome; Testing; Transgenic Mice; Tyrosine; Validation; cell motility; chemotherapy; genetic regulatory protein; improved; leukemia; leukemogenesis; mRNA Expression; mutant; novel; novel strategies; public health relevance; self-renewal; stem

DESCRIPTION (provided by applicant): A fundamental property of leukemic stem cells (LSCs) is clonal dominance. Clonal dominance refers to the clonal expansion of LSCs within the bone marrow microenvironment at the expense of normal hematopoietic cells. The mechanisms by which mutations that accumulate during leukemogenesis confer clonal dominance are largely unknown. Severe congenital neutropenia (SCN) is a bone marrow failure syndrome characterized by a marked propensity to develop acute myeloid leukemia. Truncation mutations of CSF3R, encoding the G-CSF receptor (G-CSFR), are common early mutations associated with leukemic progression in patients with SCN. We previously described transgenic mice (termed d715 G-CSFR) carrying a knock-in mutation of Csf3r that reproduces a mutation found in SCN. Our preliminary data show that the d715 G-CSFR confers a strong clonal advantage at the hematopoietic stem cell (HSC) level. Importantly, the clonal HSC advantage is dependent upon G-CSF administration, providing a novel, physiological, and "inducible" model to study clonal dominance. We propose to use this model to characterize the molecular mechanisms by which HSCs expressing mutant CSF3R gain clonal dominance. A better understanding of these mechanisms may provide novel strategies to develop molecular therapies that specifically target LSCs. This is highly relevant, since there is evidence that LSCs are inherently resistant to most current chemotherapy. Preliminary data suggest that accentuated STAT5 activation by the d715 G-CSFR is a proximal signal mediating the clonal HSC advantage. This hypothesis will be tested by conditionally deleting Stat5 and assessing the effect on HSC function. In specific aim 2, we will identify genes that are dysregulated by G-CSF in d715 G-CSFR HSCs and prioritize them for biological validation. Preliminary mRNA expression profiling studies have identified two candidate genes that are differentially induced by G-CSF in d715 G-CSFR HSC: Cdkn1a (p21cip1/waf1) and Enah. We hypothesize that induction of Cdkn1a expression by the d715 G-CSFR allows for HSC proliferation without loss of self-renewal. We also hypothesize that increased Enah expression favorably alters the interaction of HSCs with bone marrow stromal. The following specific aims are proposed. Aim 1. We will determine whether Stat5 mediates the clonal advantage of HSCs expressing the d715 G-CSFR. Aim 2. We will identify genes dysregulated by G-CSF in d715 G-CSFR HSCs that contribute to clonal dominance. Aim 3. We will define the role of Cdkn1a and Enah in the clonal advantage of HSCs expressing the d715 G-CSFR. PUBLIC HEALTH RELEVANCE: Clonal dominance is a fundamental but poorly understood property of all leukemias that allows the leukemic stem cell to expand at the expense of normal blood cells. The goal of this research is to improve our understanding of the pathways that mediate clonal dominance. We believe this research will lead to novel strategies to specifically target the leukemic stem cell and ultimately lead to improved cure rates in individuals with leukemia.

描述（由申请人提供）：白血病干细胞（LSC）的一个基本特性是克隆优势。克隆优势是指LSC在骨髓微环境中以正常造血细胞为代价的克隆扩增。白血病发生过程中积累的突变赋予克隆优势的机制在很大程度上是未知的。严重先天性中性粒细胞减少症（SCN）是一种骨髓衰竭综合征，其特征是明显倾向于发展为急性髓系白血病。编码G-CSF受体（G-CSFR）的CSF 3R截短突变是与SCN患者白血病进展相关的常见早期突变。我们先前描述了携带Csf 3r敲入突变的转基因小鼠（称为d 715 G-CSFR），其复制SCN中发现的突变。我们的初步数据显示，d 715 G-CSFR在造血干细胞（HSC）水平上具有很强的克隆优势。重要的是，克隆HSC的优势是依赖于G-CSF管理，提供了一种新的，生理的，和“诱导型”模型来研究克隆优势。我们建议使用该模型来表征表达突变型CSF 3R的HSC获得克隆优势的分子机制。对这些机制的更好理解可能为开发特异性靶向LSC的分子疗法提供新的策略。这是高度相关的，因为有证据表明LSC对目前大多数化疗具有固有的抗性。初步数据表明，由d 715 G-CSFR引起的STAT 5活化是介导克隆HSC优势的近端信号。将通过有条件地删除Stat 5并评估对HSC功能的影响来检验该假设。在具体目标2中，我们将鉴定d 715 G-CSFR HSC中G-CSF失调的基因，并将其优先用于生物学验证。初步的mRNA表达谱研究已经确定了在d 715 G-CSFR HSC中由G-CSF差异诱导的两个候选基因：Cdkn 1a（p21 cip 1/waf 1）和Enah。我们假设d 715 G-CSFR诱导Cdkn 1a表达允许HSC增殖而不丧失自我更新。我们还假设Enah表达的增加有利地改变了HSC与骨髓基质的相互作用。提出了以下具体目标。目标1.我们将确定Stat 5是否介导表达d 715 G-CSFR的HSC的克隆优势。目标二。我们将鉴定d 715 G-CSFR HSC中G-CSF失调的基因，这些基因有助于克隆优势。目标3.我们将确定Cdkn 1a和Enah在表达d 715 G-CSFR的HSC的克隆优势中的作用。公共卫生关系：克隆优势是所有白血病的一个基本但知之甚少的特性，它允许白血病干细胞以牺牲正常血细胞为代价进行扩增。这项研究的目的是提高我们对介导克隆优势的途径的理解。我们相信，这项研究将导致新的战略，专门针对白血病干细胞，并最终导致提高治愈率的个人与白血病。