Targeting the Pim 1 Protein Kinase to Overcome Resistance to AKT Inhibitors

描述（由申请人提供）：迄今为止，靶向信号转导途径开发新的前列腺癌治疗方法的成功受到耐药性机制的后续发展的限制。在几乎70%的转移性前列腺癌病例中发现的高度活化的AKT蛋白激酶是该疾病治疗的重要靶点。本研究的初步数据表明，在前列腺癌细胞系中添加AKT抑制剂可诱导细胞表面受体酪氨酸激酶（RTKs）显著增加，RTKs通过提高ERK活性来限制这些抑制剂的活性。重要的是，研究还表明AKT抑制剂诱导Pim-1蛋白激酶，这种酶与前列腺癌的发生和发展有关。该研究小组发现，通过siRNA或基因工程小鼠成纤维细胞抑制Pim-1会抑制AKT抑制剂诱导rtk的反馈。利用Kraft实验室团队开发的一种小分子Pim-1抑制剂，他们已经证明AKT和Pim-1抑制剂的组合在组织培养中协同阻止前列腺癌细胞的生长，并显著抑制免疫抑制动物的肿瘤生长。得到的数据表明AKT和Pim抑制剂调节rtk的翻译。这些令人兴奋的发现导致了一种独特的假设，即AKT抑制剂治疗会导致pim -1导向的反馈回路，诱导rtk，进而刺激ERK活性的增加。因此，AKT和Pim抑制剂的联合将中断Pim-1的诱导并协同杀死前列腺癌。本提案的具体目的是通过以下方法来探索和验证这一假设：1)在复杂的细胞培养和前列腺癌动物模型中证明，抑制Pim-1活性可以增强AKT抑制剂对肿瘤的杀伤作用；2)破译AKT抑制剂如何增加Pim-1蛋白激酶并调节翻译以增加RTK水平；3)探索如何最好地联合使用这些药物来杀死肿瘤和抑制转移性癌症，并检查AKT和Pim抑制剂的联合使用是否诱导前列腺肿瘤中活性氧（ROS）的显著增加。这些研究将确定rtk、磷酸化ERK和Pim-1水平作为AKT抑制剂作用的潜在临床重要中间标志物。提出的研究设计将利用独特的基因工程小鼠模型，核糖体分析和足印来探索这些问题。完成后，这些研究将集中关注与Pim和AKT抑制剂联合治疗靶向反馈耐药机制的潜力。这种组合将显著提高目前正在研究的用于治疗前列腺癌的单药疗法的反应。

DESCRIPTION (provided by applicant): The success of targeting signal transduction pathways for the development of new prostate cancer therapies has been limited to date by the subsequent development of drug resistance mechanisms. Highly activated AKT protein kinase found in almost 70% of cases of metastatic prostate cancer are an important target for therapies in this disease. Preliminary data in this proposal demonstrate that the addition of AKT inhibitors to prostate cancer cell lines induces a marked increase in cell surface receptor tyrosine kinases (RTKs) that function to limit the activity of these inhibitors in part by elevating ERK activity. Importantly, it is also demonstrated that AKT inhibitors induce the Pim-1 protein kinase, an enzyme that has been implicated in prostate cancer initiation and progression. This research team has discovered that knocking down Pim-1 either by siRNA or in genetically engineering mouse fibroblasts will inhibit the feedback in which AKT inhibitors induce RTKs. Using a small molecule Pim-1 inhibitor developed by the Kraft laboratory team, they have demonstrated that the combination of an AKT and Pim-1 inhibitor synergistically blocks prostate cancer cell growth in tissue culture, and markedly inhibits the growth of tumors in immunosuppressed animals. Data obtained suggests that AKT and Pim inhibitors regulate the translation of RTKs. These exciting findings lead to the unique hypothesis that AKT inhibitor treatment causes a Pim-1-directed feedback loop that induces RTKs that in turn stimulates increases in ERK activity. Thus, the combination of an AKT and Pim inhibitor will interrupt the induction of Pim-1 and synergize to kill prostate cancer. The specific aims in this proposal are to explore and validate this hypothesis by: 1) demonstrating in complex cell culture and animal models of prostate cancer that knocking down Pim-1 activity enhances AKT inhibitor tumor killing; 2) deciphering how AKT inhibitors increase the Pim-1 protein kinase and modulate translation to increase RTK levels; and 3) exploring how these agents can be best combined for tumor killing and to inhibit metastatic cancer, and examining whether the combination of AKT and Pim inhibitors induces a marked increase in reactive oxygen species (ROS) in prostate tumors. These studies will identify RTKs, phosphorylated ERK, and Pim-1 levels as potentially clinically important intermediate markers of AKT inhibitor action. The proposed study designs will make use of unique genetically engineered mouse models, and ribosome profiling and foot printing to explore these questions. When completed, these studies will focus attention on the potential for the development of combination therapies with Pim and AKT inhibitors to target feedback resistance mechanisms. This combination would markedly enhance responses to single agent therapies currently under investigation for the treatment of prostate cancer.