Eradicating leukemic stem cells in juvenile myelomonocytic leukemia

根除幼年粒单核细胞白血病中的白血病干细胞

• 批准号: 10722045
• 负责人: CHENG-KUI QU
• 金额: $ 18.29万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10722045
• 关键词: Acceleration; Address; Adolescent; Allogenic; Antimalarials; Area; Cell Death Induction; Cell Separation; Cells; Characteristics; Childhood; Clinical; Clinical Research; DNA Sequence Alteration; Development; Diagnosis; Drug resistance; Experimental Leukemia; FDA approved; Funding Opportunities; Growth; Hematologic Neoplasms; Hematopoietic; Hematopoietic Neoplasms; Hematopoietic System; Hematopoietic stem cells; Heterozygote; Hyperactivity; Impairment; Juvenile Myelomonocytic Leukemia; Knock-in Mouse; Laboratories; Maintenance; Malignant Neoplasms; Methodology; Modeling; Mus; Mutant Strains Mice; Mutate; Mutation; Myeloproliferative disease; Outcome; Pathogenesis; Pathway interactions; Patient Care; Patients; Penetrance; Pharmaceutical Preparations; Phase; Population; Prevention; Prognosis; Property; Protein Dephosphorylation; Protein Tyrosine Phosphatase; Proteins; Relapse; Research; Risk; Role; Signal Pathway; Signal Transduction; Signaling Protein; Source; Stem cell transplant; Techniques; Testing; Therapeutic; Therapeutic Effect; Transplantation; Treatment Failure; Tyrosine Phosphorylation; Work; Xenograft Model; anticancer research; atovaquone; cancer therapy; early childhood; inhibitor; juvenile myelomonocytic leukemia cell; leukemia; leukemic stem cell; mouse model; mutant; neoplastic cell; novel; novel strategies; novel therapeutic intervention; pharmacologic; pre-clinical; precursor cell; response; self-renewal; standard of care; stem cells; therapeutic evaluation; therapeutically effective; tumor eradication; tumor initiation

Project Summary Juvenile myelomonocytic leukemia (JMML), a clonal hematological malignancy of early childhood, has limited therapeutic options. While the current standard of care for patients with JMML relies on allogeneic stem cell transplant, 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 gives rise to the bulk of tumor cells. This reservoir of tumor cells is responsible for the long-term maintenance of leukemia growth and is also a major source of drug resistance. It remains a critical challenge to develop effective therapeutics to eradicate these tumor initiating cells. A novel treatment approach focused on the unique characteristics and vulnerabilities of LSCs is needed in order to address this problem. JMML is associated with genetic mutations in the signaling proteins involved in the Ras pathway, among which the protein tyrosine phosphatase Ptpn11 (Shp2), a positive regulator of Ras signaling, is most frequently mutated (heterozygous). 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 created a line of conditional knock-in mice with the Ptpn11E76K mutation, the most common mutation found in JMML. Induction of the Ptpn11E76K/+ mutation in the hematopoietic system (Ptpn11E76K/+/Mx1-Cre+ mice) resulted in JMML-like myeloproliferative neoplasm (MPN) with full penetrance, suggesting a causative role of this mutation in the pathogenesis of JMML. With this unique mouse model, we have recently discovered that while the Ras/Erk signaling pathway was aberrantly enhanced, Stat3 activity as reflected by tyrosine phosphorylation (Tyr705) decreased by ~70% in Ptpn11E76K/+ mutant stem cells (referred to as LSCs since they could reproduce the same hematological malignancy in transplants) compared to that in wild-type (Ptpn11+/+/Mx1-Cre+) control stem cells. The decrease in Stat3 activity was apparently caused by the accelerated dephosphorylation of Stat3 by the hyperactive Shp2 E76K mutant because Stat3 is one of Shp2 substrate proteins. Importantly, Ptpn11E76K/+ LSCs appear to rely on Stat3 for self-renewal and maintenance - the deletion of Stat3 dramatically decreased the LSC pool in Ptpn11E76K/+/Mx1-Cre+/Stat3fl/fl double mutant mice. Consequently, these double mutant mice died rapidly, while none of Ptpn11E76K/+/Mx1-Cre+/Stat3+/+ or Ptpn11+/+/Mx1-Cre+/Stat3fl/fl single mutant mice did. The synthetic lethality induced by Stat3 deletion in Ptpn11 E76K mutant stem cells raises an intriguing possibility, that is, diminished Stat3 activity is an Achilles' heel of Ptpn11 mutated (Shp2 hyperactivated) LSCs, making them vulnerable to pharmacological inhibition of Stat3. We plan to test this hypothesis and accomplish the objective of this proposal by pursuing the following two aims. 1) To define the role of Stat3 in maintenance of LSCs in Ptpn11 (Shp2) mutated JMML. 2) To test the therapeutic effects of the Stat3 inhibitor atovaquone in the mouse model and patient cells-derived xenograft models of Ptpn11 associated JMML. This work may lead to a novel therapeutic strategy to deplete LSCs in this JMML subtype.

项目摘要 幼年性粒单核细胞白血病(JMML)是一种儿童早期的克隆性血液系统恶性肿瘤， 治疗选择。虽然目前治疗JMML患者的标准依赖于异基因干细胞 移植，复发仍然是治疗失败的主要原因，很可能是由于白血病的持久性 干细胞(LSCs)，一小部分自我更新的前体细胞，产生大量的肿瘤细胞。 这种肿瘤细胞的储存库负责长期维持白血病的生长，也是主要的 耐药性的来源。开发有效的治疗方法来根除这些疾病仍然是一个关键的挑战。 肿瘤始动细胞。一种新的治疗方法，专注于肺炎的独特特征和脆弱性 为了解决这个问题，需要LSC。JMML与信号中的基因突变有关 参与RAS途径的蛋白质，其中酪氨酸磷酸酶Ptpn11(Shp2)为阳性 RAS信号调节因子，是最常见的突变(杂合体)。这些突变导致的 Shp2和Ptpn11突变的JMML患者在所有亚型中预后最差 JMML。我们创造了一系列带有Ptpn11E76K突变的条件性敲入小鼠，这是最常见的突变 在JMML中找到。Ptpn11E76K/+/Mx1-Cre+小鼠体内Ptpn11E76K/+突变的诱导 导致了JMML样骨髓增生性肿瘤(MPN)，提示这是一种致病作用 JMML发病机制中的突变。通过这种独特的老鼠模型，我们最近发现，虽然 Ras/Erk信号通路异常增强，STAT3活性通过酪氨酸磷酸化反映 (Tyr705)在Ptpn11E76K/+突变干细胞(称为LSCs)中下降了~70%，因为它们可以繁殖 与野生型(Ptpn11+/+/Mx1-Cre+)对照比较 干细胞。STAT3活性的下降明显是由于STAT3的加速去磷酸化引起的 因为STAT3是Shp2底物蛋白之一，所以被高活性的Shp2 E76K突变体。重要的是，Ptpn11E76K/+ LSC似乎依赖STAT3进行自我更新和维护-STAT3的删除显著减少了 Ptpn11E76K/+/Mx1-Cre+/Stat3fl/fl双突变小鼠LSC池。结果，这些双突变小鼠死亡 而Ptpn11E76K/+/Mx1-Cre+/STAT3+/+或Ptpn11+/+/Mx1-Cre+/Stat3fl/fl单一突变小鼠均未检测到。这个 Ptpn11 E76K突变干细胞中STAT3缺失导致的合成致死性提出了一种有趣的可能性，即 STAT3活性降低是Ptpn11突变(Shp2高激活)LSCs的致命弱点，使它们 易受STAT3的药理抑制。我们计划检验这一假设，并实现以下目标 这项建议通过追求以下两个目标来实现。1)定义STAT3在Ptpn11中LSC维护中的作用 (Shp2)突变JMML。2)检测STAT3抑制剂阿托瓦酮对小鼠模型的治疗作用 和患者细胞来源的Ptpn11相关JMML的异种移植模型。这部作品可能会写成一部小说 去除这种JMML亚型中的LSCs的治疗策略。