Role of NF-kB in hematopoietic stem cells and leukemia-initiating cell formation

NF-kB 在造血干细胞和白血病起始细胞形成中的作用

• 批准号: 8433499
• 负责人: CHRISTOPHER KLUG
• 金额: $ 27.72万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-02-09 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8433499
• 关键词: 1-Phosphatidylinositol 3-Kinase; AML1-ETO fusion protein; Acute Myelocytic Leukemia; Address; Affect; Alleles; American; Apoptosis; Biological Response Modifiers; Blast Cell; Bone Development; Bone Marrow; British; CD34 gene; Cell Lineage; Cell Maintenance; Cell Proliferation; Cell division; Cell physiology; Cells; Chromosome abnormality; Chronic; Complex; Cytoplasm; DNA Binding; Development; Disease; Etiology; Event; Family; Genetic Transcription; Goals; Growth Factor; HOXA9 gene; Hematopoietic; Hematopoietic Stem Cell Mobilization; Hematopoietic stem cells; Homo; Human; Immune; In Vitro; Inflammation; Inhibition of Apoptosis; Malignant Neoplasms; Mediating; Mus; Mutation; Myelogenous; Myeloproliferative disease; NF-kappa B; NUP98 gene; Normal Cell; Nuclear Translocation; Oncogenic; PTEN gene; Pathway interactions; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Proto-Oncogene Protein c-kit; Proto-Oncogene Proteins c-akt; Recurrence; Regulation; Retroviral Vector; Role; Sampling; Secondary to; Signal Pathway; Signal Transduction; Spleen; Splenomegaly; Staging; Stem cells; Stimulus; Stress; TNFRSF5 gene; Testing; Transcriptional Regulation; base; chemokine; cytokine; defined contribution; dimer; in vivo; inhibitor/antagonist; leukemia; leukemic stem cell; leukemogenesis; member; monocyte; multicatalytic endopeptidase complex; novel; p65; progenitor; public health relevance; reconstitution; response; self-renewal; stem; stem cell differentiation; tumor

DESCRIPTION (provided by applicant): Constitutive activation of the classical NF-?B pathway, which principally involves RelA/p65, c-Rel, and p50, has been observed in human acute myeloid leukemia (AML) where constitutive NF-?B DNA-binding activity has been detected in myeloid blasts and in CD34? hematopoietic progenitor cells in 47-100% of all cases. In AML, constitutive NF-?B activity could be a direct downstream consequence of activating mutations affecting the PI3 kinase pathway, which is also constitutively active in the majority of AML cases and induces NF-?B through Akt signaling. In mice, constitutive activation of Akt through inducible deletion of the Akt regulatory phosphatase, PTEN, results in rapid hematopoietic stem cell (HSC) loss from bone marrow and development of a transplantable, lethal myeloproliferative disease (MPD) and AML. These studies and others have shown that constitutive activation of Akt and NF-?B distinguishes leukemia-initiating cells (LIC) from normal HSC in bone marrow. To address whether NF-?B activation in HSC is sufficient to induce LIC formation and promote MPD/AML, we expressed a constitutively active allele of I?B kinase beta (Ikk?SS/EE) in normal HSC using a retroviral vector. Analysis of mice reconstituted with Ikk?SS/EE -expressing cells showed that constitutive NF-?B activity promoted relatively rapid HSC loss from bone marrow that, unlike activated Akt, was not accompanied by the development of MPD/AML. NF-?B-mediated HSC loss was likely due to differentiation and loss of HSC self-renewal potential since there was not evidence of increased HSC apoptosis or mobilization to the spleen. Furthermore, blocking NF-?B activation in HSC by conditional deletion of the Ikk regulatory subunit, NEMO, resulted in a substantial decrease in one of the earliest multipotential progenitor subsets (c-Kit?Sca-1? cells) and an increase in absolute numbers of more primitive c-Kit?Sca-1? (KLSF) cells. NEMO loss also completely blocked proliferation of KLSF cells in vitro, which further supports an essential role for NF-?B in promoting the earliest HSC differentiation event. Together, these results demonstrate that constitutive activation of the classical NF-?B pathway, as an initiating event in AML, is not sufficient to maintain HSC or to promote development of LIC associated with AML. The primary goal of this proposal will be to test the central hypothesis that NF-?B functions in normal HSC to couple proliferation and differentiation associated with the first HSC cell division and to maintain viability of LIC subsequent to other oncogenic changes that preserve HSC self-renewal in the presence of activated NF-?B. To test this hypothesis, we will pursue the following specific aims: (1), Determine the function of NF-?B in the regulation of normal HSC maintenance, proliferation, and differentiation (2), Define the contribution of NF-?B to Akt-stimulated leukemogenesis, LT-HSC loss from bone marrow, and to leukemia-initiating cell formation and (3), Characterize whether recurrent cytogenetic abnormalities found in AML, including the translocations AML1-ETO, inv(16), or NUP98-HOXA9, can preserve HSC self-renewal in the presence of activated Akt or NF-?B.

描述（由申请人提供）：经典NF-？B途径主要涉及RelA/p65、c-Rel和p50，在人急性髓系白血病（AML）中观察到，其中组成性NF-？B DNA结合活性已被检测到在髓系母细胞和CD 34？在所有病例中，造血祖细胞占47-100%。在AML中，组成型NF-？B活性可能是影响PI 3激酶通路的激活突变的直接下游结果，PI 3激酶通路在大多数AML病例中也是组成性活性的，并诱导NF-？B通过Akt信号传导。在小鼠中，通过Akt调节性磷酸酶PTEN的诱导性缺失的Akt的组成性活化导致骨髓中的快速造血干细胞（HSC）损失和可移植的致死性骨髓增生性疾病（MPD）和AML的发展。这些研究和其他研究表明，Akt和NF-？B区分白血病起始细胞（LIC）和骨髓中的正常HSC。要解决NF-？HSC中B激活足以诱导LIC形成并促进MPD/AML，我们表达了I？B激酶β（Ikk？SS/EE）在正常HSC中的表达。Ikk？重组小鼠的分析SS/EE -表达细胞表明，组成型NF-？B活性促进HSC从骨髓中相对快速的丢失，这与活化的Akt不同，不伴随MPD/AML的发展。NF-？B介导的HSC损失可能是由于分化和HSC自我更新潜力的丧失，因为没有证据表明HSC凋亡或动员到脾脏增加。此外，阻断NF-？通过条件性删除Ikk调节亚基NEMO，HSC中的B激活导致最早的多能祖细胞亚群之一（c-Kit？Sca-1细胞）和增加的绝对数量更原始的c-Kit？Sca-1（KLSF）细胞。NEMO损失也完全阻断了体外KLSF细胞的增殖，这进一步支持了NF-？B促进HSC最早分化事件。总之，这些结果表明，经典的NF-？B通路作为AML的起始事件，不足以维持HSC或促进AML相关LIC的发展。本提案的主要目标将是测试的核心假设，NF-？B在正常HSC中的功能是将与第一次HSC细胞分裂相关的增殖和分化偶联，并在其他致癌变化后维持LIC的活力，这些致癌变化在活化的NF-？B。为了验证这一假设，我们将追求以下具体目标：（1），确定NF-？B在正常HSC维持、增殖和分化的调节中的作用（2）. B，对Akt刺激的白血病发生、LT-HSC从骨髓中的丢失以及白血病起始细胞形成的影响，以及（3），表征在AML中发现的复发性细胞遗传学异常，包括易位AML 1-ETO、inv（16）或NUP 98-HOXA 9，是否可以在活化的Akt或NF-？B。