Co-targeting BET Bromodomain Proteins and MNK Kinases in Pancreatic Cancer

越来越多的研究表明，靶向溴结构域和末端外的抑制剂， 介导mRNA转录的BET结构域蛋白具有抗胰腺导管肿瘤的作用， 腺癌（PDAC）。BET抑制剂还可以通过抑制PDAC基质的活化来使PDAC基质正常化。 癌相关成纤维细胞（CAF）。然而，BET抑制剂诱导Rac 1介导的MNK活化， 激酶，其介导mRNA翻译。重要的是，靶向MNK激酶和MNK效应子hnRNPA 1 增强BET抑制剂的功效。值得注意的是，MNK抑制剂诱导CD 8 + T细胞浸润，但其 效应子功能被肿瘤相关巨噬细胞（TAM）抑制。值得注意的是，BET抑制剂可以 减少TAM的渗透。本申请的目的是阐明通过其， BET和MNK抑制剂的组合证明了针对PDAC的抗肿瘤应答。中央 假设是该组合有效地靶向癌细胞，调节肿瘤免疫， 胰腺癌的发生与胰腺微环境有关，并使胰腺基质正常化以抑制PDAC生长。三个具体目标是 提出：1）定义和靶向负反馈回路以增强BET抑制剂在肿瘤中的抗肿瘤作用。 2）评价BET和MNK抑制剂的组合对CD 8 + T细胞浸润的作用， 3）确定BET和MNK抑制剂的组合对胰腺基质的影响。 在第一个目标下，MNK效应子hnRNPA 1和CYFIP 1的作用机制， 将评价Rac 1下游的限制BET抑制剂的功效。此外，共治疗的功效 将在PDAC的类器官和转基因小鼠模型中评价BET和MNK抑制剂的作用。为 第二个目的，联合治疗对CD 8 + T细胞浸润和活化以及巨噬细胞的影响， 将评估丰度和极化。此外，MNK激酶和MNK效应物的贡献也是重要的。 将评价巨噬细胞中的hnRNPA 1和CYFIP 1限制BET抑制剂的功效。第三 目的：在转基因小鼠中研究联合治疗对间质反应的影响 模型胰腺CAFs中MNK激酶、CYFIP 1和hnRNPA 1对限制化疗疗效的作用 还将评价BET抑制剂。此外，BET与MNK激酶活性、MNK 将在人PDAC肿瘤标本中评价效应物和基质反应。有几个创新的 该建议中的元素，包括增强PDAC中抗肿瘤反应的新治疗方法 患者;关于BET和MNK抑制剂联合治疗如何调节肿瘤的新概念 免疫微环境和基质反应的协同抗肿瘤反应;和独特的 PDAC的复杂模型的组合，包括体内原位、类器官和转基因小鼠模型。 这项拟议中的研究意义重大，因为它将具有重要的临床转化意义， 导致开发用于PDAC患者的新型组合疗法。

A growing body of research has now demonstrated that inhibitors targeting bromodomain and extra-terminal domain (BET) proteins, which mediate mRNA transcription, have anti-tumor effects against pancreatic ductal adenocarcinoma (PDAC). BET inhibitors can also normalize the PDAC stroma by suppressing the activation of cancer-associated fibroblasts (CAFs). However, BET inhibitors induce Rac1-mediated activation of MNK kinases, which mediate mRNA translation. Importantly, targeting MNK kinases and the MNK effector hnRNPA1 enhances the efficacy of BET inhibitors. Significantly, MNK inhibitors induce CD8+ T cell infiltration, but their effector function is suppressed by the tumor-associated macrophages (TAMs). Notably, BET inhibitors can decrease the infiltration of TAMs. The objective in this application is to elucidate the mechanisms by which the combination of BET and MNK inhibitors demonstrates anti-tumor responses against PDAC. The central hypothesis is that the combination effectively targets the cancer cells, modulates the tumor immune microenvironment, and normalizes the pancreatic stroma to suppress PDAC growth. Three specific aims are proposed: 1) Define and target negative feedback loops to enhance the anti-tumor effects of BET inhibitors in vivo; 2) Evaluate the effects of the combination of BET and MNK inhibitors on CD8+ T cell infiltration and activation; 3) Determine the effects of the combination of BET and MNK inhibitors on the pancreatic stroma. Under the first aim, the mechanisms by which MNK effectors hnRNPA1 and CYFIP1, which can function downstream of Rac1, limit the efficacy of BET inhibitors will be evaluated. Further, the efficacy of co-treatment with BET and MNK inhibitors will be evaluated in organoid and transgenic mouse models of PDAC. For the second aim, the effects of the combination therapy on CD8+ T cell infiltration and activation and macrophage abundance and polarization will be evaluated. In addition, the contribution of MNK kinases and the MNK effectors hnRNPA1 and CYFIP1 in macrophages to limiting the efficacy of BET inhibitors will be evaluated. In the third aim, the effects of the combination therapy on the stromal reaction will be characterized in the transgenic mouse model. The contribution of MNK kinases, CYFIP1, and hnRNPA1 in pancreatic CAFs to limiting the efficacy of BET inhibitors will also be evaluated. In addition, the relationship between BET and MNK kinase activity, MNK effectors, and stromal reaction will be evaluated in human PDAC tumor specimens. There are several innovative elements in this proposal, including the novel therapeutic approach to enhance anti-tumor responses in PDAC patients; novel concepts on how the combination therapy of BET and MNK inhibitors modulates the tumor immune microenvironment and the stromal reaction for synergistic anti-tumor responses; and the unique combination of complex models of PDAC, including in vivo orthotopic, organoid, and transgenic mouse models. This proposed research is significant because it will have important clinical-translational implications and should result in the development of novel combination therapies for PDAC patients.