Role of Shp2 in FLT3-ITD-Induced Leukemogenesis

Shp2 在 FLT3-ITD 诱导的白血病发生中的作用

• 批准号: 8444574
• 负责人: REBECCA J. CHAN
• 金额: $ 30.04万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8444574
• 关键词: Acute Myelocytic Leukemia; Acute leukemia; Adult; Adult Acute Myeloblastic Leukemia; Age-Years; Amino Acids; BAY 54-9085; Binding; Bone Marrow; Cells; Clinical Trials; Data; Development; Disease; Drops; Elderly; FLT3 gene; Family; Genes; Genetic; Growth; Guanosine Triphosphate Phosphohydrolases; Hematopoietic; High Dose Chemotherapy; Human; In Vitro; Incidence; Individual; Investigation; Ligands; Molecular; Mononuclear; Mutate; Mutation; Myelogenous; Myeloid Leukemia; Myeloproliferative disease; Nuclear; PTPN11 gene; Pathogenesis; Patients; Phenylalanine; Population; Process; Protein Tyrosine Phosphatase; Publishing; Receptor Protein-Tyrosine Kinases; Regulation; Reporting; Role; STAT5A gene; Sampling; Scientist; Somatic Mutation; Specimen; Survival Rate; Testing; Therapeutic; Tyrosine; United States; Vascular Endothelial Growth Factor Receptor-1; Xenograft Model; base; in vivo; inhibitor/antagonist; kinase inhibitor; leukemia; leukemogenesis; mortality; mutant; new therapeutic target; novel; outcome forecast; public health relevance; rho; rho GTP-Binding Proteins; statistics

DESCRIPTION (provided by applicant): Acute myeloid leukemia (AML) is a lethal disease which dramatically increases in incidence in individuals >65 years of age, the fastest growing population in the United States. Regrettably, the 5 year survival rate drops dramatically in patients over 65 years (4.3%) compared to patients less than 65 years (34.45%). These dismal statistics have led scientists to investigate the molecular mechanism(s) underlying the transforming process leading to AML in an effort to develop novel, molecularly-targeted, effective, and less toxic therapies for use in this lethal disease. Internal tandem duplications (ITD), an in-frame mutation leading to insertion or duplication of several amino acids near the juxtamembrane domain, in fms-like tyrosine kinase receptor (FLT3), are seen in nearly 25% of all AML patients and confer a poor prognosis. Expression of the Shp2 protein tyrosine phosphatase is consistently elevated in primary leukemia cell specimens from multiple adult acute leukemias compared to Shp2 levels in bone marrow mononuclear cells from healthy controls. However, how Shp2 contributes to myeloid leukemogenesis is unknown. We present preliminary studies demonstrating that Shp2 is constitutively associated with FLT3 in mutant N51-FLT3- and N73-FLT3-bearing cells and that genetic disruption of Shp2 and pharmacologic inhibition of Shp2 preferentially reduces N51-FLT3-induced hyperproliferation compared to that observed in WT FLT3-bearing cells. As a corollary, since Shp2 has been shown to regulate the activation of the Rac subfamily of Rho-GTPases in hematopoietic cells, we predicted that Rac1 and/or Rac2 may also be relevant effectors of FLT3-ITDs. Consistently, we present preliminary findings demonstrating that pharmacologic Rac inhibition using NSC23766 or genetic disruption of Rac2 results in significantly reduced N51-FLT3-induced hyperproliferation. Based on our preliminary data, the central role of STAT5 hyperactivation in FLT3-ITD-induced leukemia, and the reported positive roles of Shp2 and Rac1/Rac2 promoting activated STAT5 nuclear accumulation, the central hypothesis of this application is that, mechanistically, Shp2 and Rac1/Rac2 contribute to FLT3-ITD-induced leukemia by facilitating STAT5 nuclear localization and the expression of STAT5-responsive pro-leukemogenic genes. The objectives of this application are to define the consequences of genetic disruption of Shp2 and Rac1/Rac2 on the activation and nuclear localization of STAT5 and on the development of FLT3-ITD-induced myeloproliferative disorder (MPD) in vivo, to examine the efficacy of a Shp2 inhibitor and a Rac1 inhibitor in an AML xenograft model in vivo, and to define the intracellular tyrosines within the juxtamembrane and the duplicated juxtamembrane of FLT3-ITD that contribute to ligand-independent proliferation.

描述（由申请人提供）：急性髓系白血病 (AML) 是一种致命性疾病，在美国人口增长最快的 65 岁以上人群中发病率急剧增加。遗憾的是，与 65 岁以下患者 (34.45%) 相比，65 岁以上患者 (4.3%) 的 5 年生存率急剧下降。这些令人沮丧的统计数据促使科学家们研究导致 AML 的转化过程的分子机制，努力开发新的、分子靶向的、有效的、毒性较小的疗法来治疗这种致命疾病。内部串联重复 (ITD) 是一种框内突变，导致 fms 样酪氨酸激酶受体 (FLT3) 中近膜结构域附近的多个氨基酸插入或重复，在近 25% 的 AML 患者中可见，导致预后不良。与健康对照的骨髓单核细胞中的 Shp2 水平相比，来自多种成人急性白血病的原发性白血病细胞样本中的 Shp2 蛋白酪氨酸磷酸酶的表达持续升高。然而，Shp2 如何促进髓系白血病的发生尚不清楚。我们提出的初步研究表明，在突变型 N51-FLT3 和 N73-FLT3 携带细胞中，Shp2 与 FLT3 组成型相关，并且与 WT FLT3 携带细胞中观察到的结果相比，Shp2 的遗传破坏和 Shp2 的药理学抑制优先减少 N51-FLT3 诱导的过度增殖。作为推论，由于Shp2已被证明可以调节造血细胞中Rho-GTPase的Rac亚家族的激活，因此我们预测Rac1和/或Rac2也可能是FLT3-ITD的相关效应子。一致地，我们提出的初步研究结果表明，使用 NSC23766 的药理 Rac 抑制或 Rac2 的遗传破坏可显着减少 N51-FLT3 诱导的过度增殖。根据我们的初步数据，STAT5 过度激活在 FLT3-ITD 诱导的白血病中的核心作用，以及报道的 Shp2 和 Rac1/Rac2 促进激活的 STAT5 核积累的积极作用，本申请的中心假设是，从机制上讲，Shp2 和 Rac1/Rac2 通过促进 STAT5 核定位和表达来促进 FLT3-ITD 诱导的白血病。 STAT5 反应性促白血病基因。本申请的目的是确定 Shp2 和 Rac1/Rac2 的遗传破坏对 STAT5 的激活和核定位以及体内 FLT3-ITD 诱导的骨髓增殖性疾病 (MPD) 发展的影响，检查 Shp2 抑制剂和 Rac1 抑制剂在体内 AML 异种移植模型中的功效，并定义细胞内 近膜内的酪氨酸和 FLT3-ITD 的复制近膜内的酪氨酸有助于配体非依赖性增殖。