A New Murine Model for MPN: Pathololgy and Therapy of NF-E2 Overexpression

尽管最近我们对骨髓增生性肿瘤(MPN)的发展有了新的了解，但对这些疾病的病理生理学仍知之甚少。尤其是MPN患者转化为急性白血病的倾向尚未阐明。基于我们观察到转录因子核因子红系2(NF-E2)在大多数MPN患者中过表达，我们通过在体内过表达NF-E2建立了MPN的小鼠模型。除了JAK2 V617F和c-MPI W515X小鼠模型外，这是唯一在MPN患者中观察到分子畸变的MPN小鼠模型。NF-E2在包括造血祖细胞在内的所有造血祖细胞中均有高表达。两个独立产生的方正细胞系表现出具有MPNsj许多特征的表型，包括血小板增多、脾肿大和骨髓(BM)组织学上的MPN样改变。在NF-E2转基因(TG)小鼠中，骨髓红系、髓系和巨核系前体细胞的数量显著增加，尤其是自主的、EPO非依赖的红系集落的数量显著增加。EPO非依赖性集落是MPN患者的病因学标志。NF-E2转基因小鼠的死亡率显着增加，尸检结果与MPN患者相似，包括内脏血栓形成和出血疾病。在20个月大的时候，一只小鼠(7.6%)患上了急性白血病。因此，我们的小鼠模型表现出与MPN的许多特征非常相似的表型。此外，我们的初步数据表明，核因子-E2的过度表达可能是急性白血病发生的易感因素。基于这些数据，我们提出了以下假设：假设1：核因子-E2的过度表达改变了造血干细胞(HSCs)，导致MPN表型的发展。核因子-E2的过度表达会导致HSCs的细胞自主性改变，因此这种表型是可移植的，并构成一种造血干细胞疾病。具体目标1：进行一次和二次移植，并鉴定核转录因子-E2转基因供体和受体小鼠的干细胞室。假设2：核因子-E2的过度表达构成了白血病前期状态，并易于演变为急性白血病。具体目的2：用诱变剂N-乙基-N-亚硝脲ENU处理NF-E2转基因小鼠和对照小鼠，观察其白血病转化的频率。假设3：由核因子-E2过度表达引起的病理生理改变可以通过药物干预来治疗。特定的 目的：用目前处于MPN患者临床前或I期临床试验的药物治疗NF-E2转基因小鼠。

Despite recent advances in our understanding of the development of Myeloproliferative Neoplasms (MPNs), the pathophysiology of these disorders remains poorly understood. Especially the predisposition of MPN patients to transform to acute leukemia is not elucidated. Based on our observation that the transcription factor nuclear factor erythroid 2 (NF-E2) is overexpressed in the majority of MPN patients, we have established a murine model for MPNs, by overexpressing NF-E2 in vivo. Besides the JAK2 V617F and c-MpI W515X mouse models, this is the only murine model of MPN that employs a molecular aberration observed in MPN patients. NF-E2 was overexpressed in all hematopoietic lineages including hematopoietic progenitor cells. Two independently generated founder lines show a phenotype with many features of MPNsj including thrombocytosis, splenomegaly and MPN-like changes in bone marrow (BM) histology. The number of BM erythroid, myeloid and megakaryocytic precursors are significantly increased in NF-E2 transgenic (tg) mice, notably the number of autonomous, EPO-independent erythroid colonies. EPO-independent colonies are a pathognomonic hallmark of MPN patients. NF-E2 transgenic mice display significantly increased mortality with autopsy findings resembling those of MPN patients including splanchnic thrombosis and bleeding diatheses. At 20 months of age, one mouse (7.6%) developed acute leukemia. Our murine model therefore displays a phenotype closely resembling many features of MPN. In addition, our preliminary data indicate that NF-E2 overexpression may predispose to the development of acute leukemia. Based on this data, we formulate the following hypotheses: Hypothesis 1: NF-E2 overexpression alters hematopoietic stem cells (HSCs) resulting in the development of an MPN phenotype. NF-E2 overexpression causes cellautonomous changes in HSCs, the phenotype is therefore transplantable and constitutes a hematopoietic stem cell disorder. Specific Aim 1: To perform primary and secondary transplants and to characterize the stem cell compartment of NF-E2 transgenic donor and recipient mice. Hypothesis 2: NF-E2 overexpression constitutes a pre-leukemic state and predisposes to the evolution to acute leukemia. Specific Aim 2: To treat NF-E2 transgenic and control mice with the mutagen N-ethyl-N-nitrosourea ENU and observe the frequency of leukemic transformation. Hypothesis 3: The pathophysiological changes evoked by NF-E2 overexpression are treatable by pharmacologic intervention. Specific Aim 3: To treat NF-E2 transgenic mice with pharmacological agents currently in pre-clinical or phase I clinical trials for MPN patients.