Mnk Pathways and IFN-responses in Malignant Cells

描述（由申请人提供）：干扰素（ifn）在体外和体内都表现出重要的抗肿瘤特性，是免疫监测癌症的关键因素。这些细胞因子在临床医学中有广泛的应用，但它们在治疗许多恶性肿瘤中的应用往往受到肿瘤细胞耐药性的限制。我们已经确定了一个新的ifn信号级联，涉及激酶Mnk1和Mnk2。我们的数据表明，Mnk激酶在ifn依赖性mRNA翻译和生长抑制中发挥关键作用，在MAPK通路和ifn刺激基因（ISGs）的mRNA翻译之间提供了直接联系。该通路的参与最终调节了ifn系统中具有关键功能的蛋白产物的表达，如介导isg酰化的ISG15和其他具有生长抑制特性的蛋白。目前的建议是一种系统的方法来建立Mnk通路在ifn介导的反应产生中的作用，并定义在恶性细胞中ifn耐药发展中该级联激活缺陷的重要性。具体目标1将确定上游效应机制和参与调控Mnk通路的信号事件。研究将确定ifnr相关的Jak激酶在Mnk 1/2激活中的作用，而Jak2对核Mnk2b功能和mRNA核输出的潜在调节作用将被确定。还将评估不同的MAPKKKs和MAPKKs在IFNR参与Mnks中的贡献。特异性目标2将确定该途径的下游元件，并剖析它们在产生ifn依赖性抗肿瘤作用中的作用。eIF4E磷酸化的功能相关性以及hnRNPA1和Sprouty蛋白（Spry1和2）在ifn信号传导中的参与将被检查。研究还将确定Mnks是否调节SLFN基因的mRNA翻译，SLFN基因是一种新的细胞周期调节因子家族，我们最近发现它是ifn抗增殖反应的介质。特异性目的3将确定Mnk激酶在JAK2V617F突变的Ph（-）骨髓增生性肿瘤中IFNa抑制作用的产生中的作用。在诱导IFNa对P. Vera和ET患者的原发性克隆造血祖细胞的影响中，Mnk活性的要求将被检验；以及IFNa在JAK2V617F小鼠模型中诱导Mnk1和/或Mnk2基因靶向破坏的能力将被确定。总之，这些研究将促进我们对ifn依赖性抗白血病反应产生机制的理解；提供有关导致恶性细胞耐药事件的重要信息；并为开发新的抗肿瘤药物和克服这种耐药性的方法奠定基础。

DESCRIPTION (provided by applicant): Interferons (IFNs) exhibit important antineoplastic properties in vitro and in vivo and are key elements in the immune surveillance against cancer. These cytokines have widespread applications in clinical medicine, but their utility in the treatment of many malignancies is frequently limited by the development of neoplastic cell resistance. We have identified a novel IFN-signaling cascade, involving the kinases Mnk1 and Mnk2. Our data have established that Mnk kinases play key roles in IFN-dependent mRNA translation and growth suppression, providing a direct link between MAPK pathways and mRNA translation of IFN-stimulated genes (ISGs). The engagement of this pathway ultimately regulates expression of protein products with key functional roles in the IFN-system, such as ISG15 which mediates ISGylation and other proteins with growth inhibitory properties. The current proposal is a systematic approach to establish the roles of Mnk pathways in the generation of IFN-mediated responses and to define the importance of defects in the activation of this cascade in the development of IFN-resistance in malignant cells. Specific aim 1 will identify upstream effector mechanisms and signaling events involved in the regulation of the Mnk pathway. Studies to define the roles of IFNR-associated Jak kinases in the activation of Mnk 1/2 will be performed, while the potential regulatory effects of Jak2 on the function of nuclear Mnk2b and mRNA nuclear export will be determined. The contribution of distinct MAPKKKs and MAPKKs in engagement of Mnks by the IFNR will be also assessed. Specific aim 2 will identify downstream elements of the pathway and will dissect their roles in the generation of IFN-dependent antineoplastic effects. The functional relevance of eIF4E phosphorylation and the involvement of hnRNPA1 and Sprouty proteins (Spry1 and 2) in IFN-signaling will be examined. Studies will be also performed to determine whether Mnks regulate mRNA translation of SLFN genes, a novel family of cell-cycle regulators that we have recently identified as mediators of IFN-antiproliferative responses. Specific aim 3 will determine the role of Mnk kinases in the generation of the suppressive effects of IFNa in Ph (-) myeloproliferative neoplasms with the JAK2V617F mutation. The requirement of Mnk activity in the induction of IFNa effects on primary clonal hematopoietic progenitors from patients with P. Vera and ET will be examined; and the ability of IFNa to induce responses in JAK2V617F mouse models with targeted disruption of the Mnk1 and/or Mnk2 genes will be determined. Altogether, these studies will advance our understanding of the mechanisms of generation of IFN-dependent antileukemic responses; provide important information on the events that lead to malignant cell resistance; and form the basis for the development of novel antineoplastic agents and approaches to overcome such resistance.