Pharmcogenomic dissection of mTOR translational targets in prostate cancer

描述(申请人提供)：前列腺癌是美国男性癌症相关死亡的第二大常见原因。PI3K-AKT-mTOR通路在前列腺癌中高度失控。一个悬而未决且知之甚少的问题是，该途径最下游的信号成分4EBP-eIF4E和p70S6K在翻译水平上控制着前列腺癌发生发展过程中的基因表达。针对人类癌症mTOR信号下游翻译成分的巨大治疗潜力突显了这个问题的重要性。在这项提案中，我们使用了一种新的药物基因组学方法，它将允许我们描述蛋白质合成控制中的特定步骤，这些步骤影响到前列腺癌发展和治疗反应的后基因组控制，这在以前由于缺乏适当的遗传和分子工具而无法实现。具体地说，我们设计并验证了体内动物模型，在致癌mTOR过度激活的情况下，功能地将4EBP-eIF4E、p70S6K1和rpS6的活性恢复到正常水平。此外，我们将使用我们开发和表征的第一个mTOR的ATP活性位点抑制剂来药理学地询问mTOR下游在前列腺癌发生、发展和治疗反应中的翻译成分。在PTEN介导的前列腺上皮内瘤变(PIN)的背景下，我们的初步研究结果表明，这些抑制剂对迄今已知的异常mTOR依赖蛋白合成显示出最强的作用，并导致这种肿瘤病变的完全消退。这些抑制物能够诱导人前列腺癌细胞的细胞周期停滞和程序性细胞死亡，进一步证实了这一点。此外，我们还成功地优化并应用了一种检测前列腺癌基因组翻译的新技术，称为核糖体图谱(RP)。这导致了第一次对由致癌mTOR信号调节的前列腺癌翻译状态的全基因组功能分析，这为本拨款中提出的实验奠定了基础。综上所述，我们目前的建议，利用最先进的小鼠遗传模型、新型mTOR抑制剂和翻译图谱的融合，将提供前所未有的水平，深入了解前列腺癌发生的后基因组机制，这些机制由蛋白质合成控制决定。此外，这些研究将确定mTOR高活性的新功能生物标记物，这些标记物可能有助于预测临床结果，并为靶向人类前列腺癌mTOR信号最下游翻译成分提供临床前理论基础。

DESCRIPTION (provided by applicant): Prostate cancer is the second most common cause of cancer-related death among men in the United States. The PI3K-AKT-mTOR pathway is highly deregulated in prostate cancer. An outstanding and poorly understood question is the contribution of the most downstream signaling components of this pathway, 4EBP-eIF4E and p70S6Ks that control gene expression at the translation level towards prostate cancer development. The significance of this question is underscored by the tremendous therapeutic potential for targeting downstream translational components of mTOR signaling in human cancer. In this proposal, we employ a novel pharmacogenomic approach that will allow us to delineate specific steps in protein synthesis control that impinge on post-genomic control of prostate cancer development and therapeutic response, which has not been previously possible due to a lack of appropriate genetic and molecular tools. Specifically, we have designed and validated in vivo animal models to functionally restore the activity of 4EBP-eIF4E, p70S6K1 and rpS6 to normal levels in the setting of oncogenic mTOR hyperactivation. Furthermore, we will use the first ATP active site inhibitors of mTOR, which we have developed and characterized, to pharmacologically interrogate the downstream translational components of mTOR in prostate cancer initiation, progression and therapeutic response. In the context of PTEN-mediated prostatic intraepithelial neoplasia (PIN), our preliminary findings show that these inhibitors exhibit the strongest effect on aberrant mTOR dependent protein synthesis known to date and lead to the complete regression of this neoplastic lesion. This is further substantiated by the ability of these inhibitors to induce cell cycle arrest and programmed cell death in human prostate cancer cells. In addition, we have successfully optimized and employed a novel technology for examining translation of the prostate cancer genome, known as ribosome profiling (RP). This led to the first functional genome-wide analysis of the translational state of prostate cancer modulated by oncogenic mTOR signaling, which lays the groundwork for experiments proposed in this grant. Together, our current proposal, which utilizes a convergence of state-of-the-art genetic mouse models, novel mTOR inhibitors, and translation profiling, will provide an unprecedented level of insight into the post-genomic mechanisms of prostate cancer development dictated at the level of protein synthesis control. Moreover, these studies will identify novel functional biomarkers for mTOR hyperactivity that may aid in predicting clinical outcomes as well as provide the preclinical rationale for targeting the most downstream translational components of mTOR signaling in human prostate cancer.