Signal Transduction of Type 1 Interferons in Malignant Cells

描述（由申请人提供）：这是一个竞争性续期申请，其总体目标是定义恶性细胞中干扰素（IFN）信号传导的机制。ifn在体外和体内均表现出重要的抗肿瘤特性，是免疫监视癌症的关键因素，但其产生这种作用的机制仍有待确定。我们已经提供了第一个证据，证明mTOR信号级联是由IFN受体（IFNRs）参与的，并通过控制真核起始因子4E （eIF4E）和eIF4F复合物来调节帽依赖性mRNA翻译。值得注意的是，与致癌信号相比，我们的研究为ifn信号特异性和mTORC2复合物的差异使用提供了证据。我们的研究表明mTORC2复合物在ifn信号传导中具有双重调节作用，控制下游通路调节isg的转录和mRNA翻译。目前的建议是一种系统的方法来剖析这些复合物在ifn信号传导中的功能和作用，并定义它们在ifn抗肿瘤作用产生中的相关性。特异性目标1将识别上游IFNR产生的导致mTORC2激活的信号，并将确定I型IFNR参与mTORC2的特异性机制。它包括研究剖析ifnr相关激酶在这一过程中的作用；研究确定不同Sin1亚型的差异参与是否解释了ifn系统的特异性；和筛选工作，以确定新的Rictor和sin1相互作用的ifn信号元件。特异性目标2将定义mTORC2复合物控制ISG表达的机制及其在恶性细胞中产生ifn抑制反应中的作用。它包括定义mTORC2复合物在ifnr激活的信号级联中的作用，这些信号级联调节ISGs的转录激活和mRNA翻译；IFN活化mTORC2复合物对AGC激酶影响的实验研究以及剖析mTOR通路中不同下游效应元件在产生ifn抗增殖反应中的要求的研究。特异性目的3将研究mtor依赖信号在ifn在Ph（-）骨髓增生性肿瘤（mpn）中的抗肿瘤作用。JAK2V617F小鼠模型将在AKT -/-、S6K -/-和Pdcd4 -/- KO小鼠中建立，并将评估IFN -在存在或不存在不同通路效应物的情况下诱导体内抗白血病反应的能力。体外和体内的mpn患者原发性造血前体中ifn依赖性mTOR通路的激活将被评估并与ifn敏感性相关。总之，这些研究将促进我们对控制ifn抗肿瘤反应产生的信号机制的理解，并将提供导致恶性细胞对ifn耐药的事件的重要信息。最终，它们可能形成克服干扰素耐药性的新方法的基础。

DESCRIPTION (provided by applicant): This is a competing renewal application whose overall objective is to define the mechanisms of interferon (IFN)-signaling in malignant cells. IFNs exhibit important antineoplastic properties in vitro and in vivo and are key elements in the immune surveillance against cancer, but the mechanisms by which they generate such effects remain to be defined. We have provided the first evidence that the mTOR signaling cascade is engaged by IFN receptors (IFNRs) and regulates cap-dependent mRNA translation via control of the eukaryotic initiation factor 4E (eIF4E) and the eIF4F complex. Remarkably, our studies have provided evidence for signaling specificity and differential use of mTORC2 complexes by IFNs, as compared to oncogenic signals. Our studies suggest dual regulatory roles for mTORC2 complexes in IFN-signaling, controlling downstream pathways that regulate both transcription and mRNA translation of ISGs. The current proposal is a systematic approach to dissect the functions and roles of these complexes in IFN-signaling and to define their relevance in the generation of the antineoplastic effects of IFNs. Specific aim 1 will identify upstream IFNR-generated signals that lead to mTORC2 activation and will determine the mechanisms of specificity of mTORC2 engagement by the Type I IFNR. It includes studies to dissect the role of IFNR-associated kinases in the process; studies to define whether differential engagement of distinct Sin1 isoforms accounts for specificity in the IFN-system; and screening efforts to identif novel Rictor- and Sin1-interacting IFN-signaling elements. Specif ic aim 2 will define the mechanisms by which mTORC2 complexes control ISG expression and their roles in the generation of IFN-inhibitory responses in malignant cells. It includes experiments to define the roles of mTORC2 complexes in IFNR-activated signaling cascades that regulate transcriptional activation and mRNA translation of ISGs; experiments on the effects of IFN�-activated mTORC2 complexes on AGC kinases; and studies to dissect the requirement of distinct downstream effector elements of mTOR pathways in the generation of IFN-antiproliferative responses. Specif ic aim 3 will examine the roles of mTOR-dependent signals in the antineoplastic effects of IFNs in Ph (-) myeloproliferative neoplasms (MPNs). JAK2V617F mouse models will be established in AKT -/-, S6K -/- and Pdcd4 -/- KO mice, and the ability of IFN� to induce antileukemic responses in vivo, in the presence or absence of distinct effectors of the pathway, will be assessed. The activation of IFN-dependent mTOR pathways in primary hematopoietic precursors from patients with MPNs in vitro and in vivo will be assessed and correlated with IFN-sensitivity. Altogether, these studies will advance our understanding of the signaling mechanisms controlling generation of IFN-antitumor responses and will provide important information on the events that lead to malignant cell resistance to IFNs. Ultimately, they may form the basis for new approaches to overcome IFN-resistance.