Exploiting TOR Signaling for Cancer Drug Discovery

描述（由申请人提供）：TOR（雷帕霉素靶点）蛋白激酶途径的功能是真核生物细胞生长控制的核心。雷帕霉素及其类似物在癌症治疗方面的潜力正在深入研究中。本提案的广泛、长期目标是：(1)更好地理解TOR信号在细胞生长控制中的分子机制，(2)阐明细胞对雷帕霉素的敏感性机制，(3)了解如何利用TOR信号特性来推进与该途径相关的人类疾病的治疗。为了实现这些目标，我们正在开发一种新的化学遗传学和蛋白质组学方法，以快速有效地利用出芽酵母，酿酒酵母，这是研究TOR信号，细胞生长控制和癌症相关的保守途径的既定模型。在初步研究中，我们发现了两类可以改变雷帕霉素生长抑制作用的新型小分子：smir（雷帕霉素的小分子抑制剂）和SMERs（雷帕霉素的小分子增强剂）。我们对smir的研究发现了调控TOR通路活性的新机制。我们将采用类似的概念和方法来研究SMERs，我们设想SMERs可用于a)增强雷帕霉素的治疗效果，b)治疗雷帕霉素不敏感的肿瘤，和/或c)防止雷帕霉素耐药性的发展，所有这些都有望对tor靶向治疗产生重大影响。将被测试的假设是，TOR通路的扰动会产生一组不同的细胞状态，这些状态可以选择性地靶向导致癌细胞适应性的降低（或丧失）。我们的具体目标是：1)进行高通量筛选，以鉴定干扰TOR通路的合成致死小分子；2)表征SMERs并测试其在哺乳动物细胞中的活性；3)鉴定SMERs的蛋白靶点并阐明其在TOR通路调节中的机制。一旦成功完成，该项目将为癌症药物发现、靶标识别和治疗机制研究提供一个新的范例，这与NCI/NIH的使命密切相关。寻找有效的癌症治疗方法对科学界和医学界提出了一个令人信服的挑战。我们的研究旨在结合这一领域最强大的两个概念，即分子靶向治疗和合成致死性，以实现治疗干预的最大特异性、有效性和安全性。我们相信我们的研究将为TOR信号传导的基本机制以及TOR靶向治疗提供新的思路。此外，我们在这里开发和测试的方法将广泛适用于其他癌症药物、其他途径和其他人类疾病的研究。

DESCRIPTION (provided by applicant): The function of the TOR (target of rapamycin) protein kinase pathway is central to cell growth control in eukaryotes. Rapamycin and its analogs are under intense investigation for their potential in cancer therapies. The broad, long-term goals of this proposal are: (I) To better understand the molecular mechanisms of TOR signaling in cell growth control, (II) To elucidate the mechanisms of cellular sensitivity to rapamycin, and (III) To learn how TOR signaling properties can be exploited to advance the treatment for human diseases linked to this pathway. Towards these ends, we are developing a novel chemical-genetic and proteomic approach to rapidly and efficiently discover using the budding yeast, Saccharomyces cerevisiae, which is an established model to study TOR signaling, cell growth control, and cancer-related, conserved pathways. In preliminary studies, we have discovered two classes of novel small molecules that modify rapamycin's growth-inhibitory effects: the SMIRs (small molecule inhibitors of rapamycin) and the SMERs (small molecule enhancers of rapamycin). Our studies of the SMIRs have led to the discovery of new mechanisms in regulating TOR pathway activity. We will apply similar concepts and methods to study the SMERs, which we envision to be useful for a) enhancing rapamycin's therapeutic efficacy, b) treating rapamycin-insensitive tumors, and/or c) preventing the development of drug resistance to rapamycin, all of which are expected to have significant impact on TOR-targeted therapies. The hypothesis that will be tested is that perturbations of the TOR pathway create a set of distinct cellular states that can be selectively targeted to cause reduction (or loss) in fitness in cancer cells. Our specific Aims are: 1) to perform high- throughput screening to identify small molecules that are synthetic-lethal with perturbations of the TOR pathway, 2) to characterize the SMERs and test their activities in mammalian cells, and 3) to identify the protein targets for the SMERs and elucidate their mechanisms in TOR pathway modulation. Upon successful completion, the project will have demonstrated a new paradigm for cancer drug discovery, target identification, and mechanism studies in search of cures, which aligns closely with the missions of the NCI/NIH. The search for effective therapies for cancer presents a compelling challenge to the scientific and medical community. Our studies aim to combine two of the most powerful concepts in this area, namely molecularly targeted therapy and synthetic lethality, to achieve greatest specificity, efficacy, and safety in therapeutic intervention. We believe that our studies will shed new light on basic mechanisms of TOR signaling as well as TOR-targeted therapy. Furthermore, the methods that we develop and test here will be broadly applicable to the study of other cancer drugs, other pathways and other human diseases.