Synthetic lethality in leukemic stem cells in juvenile myelomonocytic leukemia

幼年型粒单核细胞白血病干细胞的综合致死率

• 批准号: 10308711
• 负责人: CHENG-KUI QU
• 金额: $ 21.44万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-12-01 至 2022-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10308711
• 关键词: Adolescent; Antipsychotic Agents; Area; Biological; Blood; Cell Death; Cells; Characteristics; Childhood; Clinical; DNA Sequence Alteration; Data; Development; Disease; Drug resistance; Experimental Leukemia; Exploratory/Developmental Grant; Funding Opportunities; Growth; Growth Factor; Hematologic Neoplasms; Hematopoietic; Hematopoietic stem cells; Hyperactivity; Impairment; Investigation; Juvenile Myelomonocytic Leukemia; Knock-in; Knock-in Mouse; Knock-out; Lead; Maintenance; Malignant Neoplasms; Methodology; Modeling; Mus; Mutant Strains Mice; Mutate; Mutation; Myeloproliferative disease; NIH Program Announcements; Outcome; Pathogenesis; Pathway interactions; Patients; Penetrance; Pharmacology; Phenotype; Phosphorylation; Pimozide; Plant Roots; Population; Prognosis; Property; Protein Dephosphorylation; Protein Tyrosine Phosphatase; Proteins; Relapse; Research; Risk; Role; Signal Transduction; Signaling Protein; Source; Techniques; Testing; Therapeutic; Therapeutic Effect; Transplantation; Treatment Failure; Tyrosine; Xenograft Model; anticancer research; base; cancer diagnosis; cytokine; early childhood; inhibitor; leukemia; leukemic stem cell; mouse model; mutant; neoplastic cell; novel; novel strategies; novel therapeutic intervention; pre-clinical; precursor cell; response; self-renewal; stem cells; therapeutic development; therapeutic evaluation; therapeutically effective; transcription factor

Project Summary Juvenile myelomonocytic leukemia (JMML), a clonal hematological malignancy of early childhood, has limited therapeutic options. Relapse remains the main cause of treatment failure, most likely due to the persistence of leukemic stem cells (LSCs), a small population of self-renewing precursor cells that give rise to the bulk of tumor cells. This reservoir of tumor cells is responsible for long-term maintenance of leukemia growth and is also a major source of drug resistance. Therefore, a novel treatment approach focused on the unique characteristics and vulnerabilities of LSCs is needed in order to target this root cause of JMML. However, it remains a critical challenge how these leukemic precursor cells may be eradicated. JMML is caused by various genetic mutations in the signaling proteins involved in the Ras pathway, among which protein tyrosine phosphatase Ptpn11 (Shp2), a positive regulator of the Ras pathway, is most frequently mutated. These mutations cause greatly increased catalytic activity of Shp2, and JMML patients with Ptpn11 mutations have the worst prognosis in all subtypes of JMML. We previously created a line of conditional knock-in mice with the Ptpn11E76K mutation, the most common and active Ptpn11 mutation found in JMML. Induction of the Ptpn11E76K/+ mutation in these mice (Ptpn11E76K/+/ Mx1-Cre+) resulted in JMML-like myeloproliferative neoplasm (MPN) with full penetrance, suggesting a causative role of this mutation in the pathogenesis of JMML. In an effort to understand the biological properties of leukemic precursor cells in JMML, we recently examined mutated hematopoietic stem cells in this mouse model (referred to as LSCs) and found that Stat5 was hyper-activated. More importantly, Ptpn11E76K/+ LSCs appeared to rely on Stat5 for maintenance and self-renewal because deletion of Stat5 in Ptpn11E76K/+/Mx1-Cre+/Stat5fl/fl double mutant mice resulted in massive LSC cell death while neither Stat5 knockout nor Ptpn11E76K/+ knock-in alone mice had such phenotypes in stem cells. Consequently, the LSC pool in Ptpn11E76K/+/Mx1-Cre+/Stat5fl/fl double mutant mice was markedly decreased. Further mechanistic investigation revealed that this was because tyrosine (Tyr705) phosphorylation of Stat3, one of the Shp2 substrate proteins, was decreased by 3 to 5-fold in Ptpn11E76K/+ LSCs likely due to enhanced dephosphorylation by the hyperactive Shp2 E76K mutant. Thus, diminished Stat3 activity represents an Achilles’ heel of Ptpn11E76K/+ LSCs, making them vulnerable to Stat5 depletion-induced cell death. The synthetic lethality induced by loss of Stat5 in Ptpn11-activated JMML stem cells raises an intriguing possibility, i.e., pharmacological inhibition of Stat5 might be effective in eradicating LSCs in this subtype of JMML. We plan to test this hypothesis and accomplish the objective of this project by pursuing the following two aims. 1) To define the role of Stat5 in maintenance of LSCs in Ptpn11-associated JMML. 2) To test the therapeutic effects of the Stat5 inhibitor pimozide, a clinically used antipsychotic drug, in Ptpn11 (Shp2)-activated JMML.

项目摘要 幼年粒单核细胞白血病（JMML）是一种发生于儿童早期的克隆性血液恶性肿瘤， 治疗选择复发仍然是治疗失败的主要原因，最有可能是由于 白血病干细胞（LSC）是一小群自我更新的前体细胞，可产生大量肿瘤细胞， 细胞这种肿瘤细胞的储存库负责长期维持白血病的生长，也是白血病的一个重要来源。 耐药性的主要来源。因此，一种新的治疗方法集中在独特的特点， 和LSC的脆弱性，以便针对JMML的这一根本原因。然而，它仍然是一个关键的 挑战如何根除这些白血病前体细胞。JMML是由各种基因突变引起的 在参与Ras途径的信号蛋白中，其中蛋白酪氨酸磷酸酶Ptpn 11（Shp 2）， Ras途径的正调节因子，最常发生突变。这些突变导致 Shp 2和Ptpn 11突变的JMML患者的催化活性在所有亚型中具有最差的预后。 JMML。我们之前创建了一个有Ptpn 11 E76 K突变的条件性基因敲入小鼠系，这是最常见的 和JMML中发现的Ptpn 11活性突变。在这些小鼠中诱导Ptpn 11 E76 K/+突变（Ptpn 11 E76 K/+/ Mx 1-Cre+）导致完全转移的JMML样骨髓增生性肿瘤（MPN），提示其致病性 这种突变在JMML发病机制中的作用。为了了解白血病的生物学特性， 前体细胞的JMML，我们最近检查了突变的造血干细胞在这个小鼠模型（参考 并发现Stat 5被过度激活。更重要的是，Ptpn 11 E76 K/+ LSC似乎依赖于 Stat 5用于维持和自我更新，因为Ptpn 11 E76 K/+/Mx 1-Cre+/Stat 5 fl/fl双突变体中Stat 5缺失 小鼠导致大量的LSC细胞死亡，而Stat 5敲除或Ptpn 11 E76 K/+敲入单独的小鼠都没有 干细胞中的这种表型。因此，Ptpn 11 E76 K/+/Mx 1-Cre+/Stat 5 fl/fl双突变小鼠中的LSC池 明显下降。进一步的机理研究表明，这是因为酪氨酸（Tyr 705） 在Ptpn 11 E76 K/+ LSC中，Shp 2底物蛋白之一Stat 3的磷酸化降低了3至5倍 可能是由于过度活跃的Shp 2 E76 K突变体增强了去磷酸化。因此，Stat 3活性降低 代表了Ptpn 11 E76 K/+ LSC的致命弱点，使它们容易受到Stat 5耗尽诱导的细胞死亡的影响。 在Ptpn 11激活的JMML干细胞中，Stat 5缺失诱导的合成致死性引起了一个有趣的问题。 可能性，即，Stat 5的药理学抑制可能有效地根除JMML的这种亚型中的LSC。 我们计划通过追求以下两个目标来验证这一假设并实现本项目的目标。第一章 明确Stat 5在Ptpn 11相关JMML中维持LSC中的作用。2)为了测试治疗效果 Stat 5抑制剂匹莫齐特（一种临床使用的抗精神病药物）在Ptpn 11（Shp 2）激活的JMML中的作用。