Role of Shp2 in FLT3-ITD induced leukemogenesis

项目摘要/摘要 尽管大多数急性髓系白血病(AML)患者对一线治疗有一过性反应 化疗，复发频繁发生，是老年AML患者最常见的死亡原因 总体治愈率仅为15%，约占AML患者总数的90%。近期全基因组 而外显子组测序研究表明，逐步积累的遗传和表观遗传变化 造血干细胞(HSCs)在白血病前干细胞(Pre-LSC)的形成中起着至关重要的作用 不仅在疾病发生中起作用，而且在白血病复发中也起作用。虽然前LSC的存在已经相当 在急性髓系白血病的人类和小鼠模型中，都有很好的文献记载，这些机制负责生长/存活 前LSC和导致这些前LSC进展为成熟LSC和AML爆炸的信号是 人们对此知之甚少。表观遗传修饰基因的突变，如TET2和DNMT3A，经常被发现 在前LSCs中，当与基因突变(如Flt3-ITD)配对时，会导致完全成熟的AML。基于 在动物模型中进行的研究，TET2或DNMT3A突变单独不会导致AML，因此单一 这些基因的突变重现了LSC前的状态。然而，这些突变与Flt3- ITD会导致AML的全面发展，并预示着人类预后不良。这些急性髓系白血病小鼠模型 以可定义的、功能改变的前LSCs和LSCs为特征的，与人类疾病非常相似 考虑到关键的分子、细胞和表型特征，并考虑到预期的识别和功能 AML中前LSCs形成和向LSCs发展的机制研究。鉴于Flt3-ITD 通常发生在存在其他协同表观遗传突变的情况下，例如TET2和DNMT3A，在这种情况下 竞争更新，我们关注Shp2如何整合来自这些不同基因(表观遗传学)的信号 调节LSCs的生长和存活的受体酪氨酸激酶)。对这件事 最后，我们有新的初步数据表明Shp2调节TET2介导的克隆性造血的丢失 通过形成涉及包括IL-6 AS在内的炎性细胞因子的前馈循环 以及通过诱导一种新的lncRNA Morrid的表达。MORRBID在AML中显著上调 患者来源的细胞，包括患有Flt3-ITD和携带TET2突变的AML患者，其中 与较差的总体存活率有关。我们发现在缺乏TET2的LSCs前期或缺乏LSCs的LSCs中MorrBid的丢失 TET2并表达Flt3-ITD，使这些细胞对凋亡易感，部分是通过上调一种蛋白- 凋亡蛋白Bim。我们进一步证明，使用一种新的变构SHP2抑制剂，目前正在进行临床试验， 有效抑制小鼠和人白血病AML细胞的生长。重要的是，SHP2抑制剂显示没有 对正常细胞的毒性，但对白血病细胞的生长有独特的影响，并与5- 氮胞苷。我们假设靶向SHP2，靶向TET2丢失介导的信号，以及Flt3-ITD 诱导信号，分别在前LSCs和LSCs中汇聚到一个新的lncRNA Morrid上。

PROJECT SUMMARY/ABSTRACT Although majority of patients with acute myeloid leukemia (AML) do respond transiently to frontline chemotherapy, relapse occurs frequently and is the most common cause of death in older AML patients who have an overall cure rate of only 15% and make up ~90% of the AML patient population. Recent whole genome and exome sequencing studies suggest that accumulation of stepwise genetic and epigenetic changes in hematopoietic stem cells (HSCs) results in the formation of pre-leukemia stem cells (pre-LSC) that play a crucial role not only in disease origination but also in leukemia relapse. While the presence of pre-LSCs has been fairly well documented in both humans and mouse models of AML, mechanisms responsible for the growth/survival of pre-LSCs and signals leading to the progression of these pre-LSCs into full-blown LSCs and AML blasts are poorly understood. Mutations in epigenetic-modifying genes, such as TET2 and DNMT3A, are frequently found in pre-LSCs and when paired with genetic mutations such as FLT3-ITD, result in full-blown AML. Based on studies performed in animal models, Tet2 or Dnmt3A mutations alone do not result in AML, and thus single mutations in these genes recapitulate a pre-LSC state. However, combinations of these mutations with FLT3- ITD lead to full-blown AML and portend a poor prognosis in humans. These AML murine models are characterized by definable, functionally altered pre-LSCs and LSCs, closely resembling human disease with regard to key molecular, cellular and phenotypic features, and allow for prospective identification and functional study of mechanisms driving the formation of pre-LSCs and progression to LSCs in AML. Given that FLT3-ITD often occurs in the presence of other cooperating epigenetic mutations such as TET2 and DNMT3A, in this competitive renewal, we have focused on how Shp2 integrates signals from these distinct genes (an epigenetic regulator vs. a receptor tyrosine kinase) to regulate the growth and survival of both pre-LSCs and LSCs. To this end, we have novel preliminary data to suggest that Shp2 regulates loss of Tet2 mediated clonal hematopoiesis in pre-LSCs by forming a feed-forward loop involving the production of inflammatory cytokines including IL-6 as well as by inducing the expression of a novel lncRNA, Morrbid. MORRBID is significantly upregulated in AML patient derived cells including in AML patients with FLT3-ITD as well as bearing TET2 mutations, where it is associated with poor overall survival. We show that loss of Morrbid in pre-LSCs lacking Tet2 or in LSCs lacking Tet2 and expressing FLT3-ITD, renders these cells susceptible to apoptosis, in part by upregulation of a pro- apoptotic protein Bim. We further demonstrate, using a novel allosteric SHP2 inhibitor, currently in clinical trials, to potently inhibit the growth of mouse and human leukemic AML cells. Importantly, SHP2 inhibitor, shows no toxicity against normal cells but uniquely impacts the growth of leukemic cells alone and in combination with 5- Azacytidine. We hypothesize that targeting SHP2, targets both Tet2 loss mediated signals, as well as FLT3-ITD induced signals, that converge on a novel lncRNA, Morrbid in pre-LSCs and LSCs, respectively.