Identifying Small Molecules To Probe the Role of Heat Shock Factor 1 in Cancer

描述（由申请人提供）：热休克反应（HSR）是一个强大的转录程序，它在全基因组范围内起作用，不仅通过诱导热休克蛋白来恢复正常的蛋白质折叠环境，而且最近的研究表明，它可以重塑控制生存、生长和代谢的全球细胞通路。在哺乳动物中，这种反应主要由热休克因子1 （HSF1）调节，这是一种转录因子，其作用方式在所有真核生物中大致上是保守的。令人惊讶的是，我们最近的工作表明，已知HSF1的许多有益作用可以增强生物体在压力下的生存，但代价是促进小鼠模型和多种潜在致癌病变驱动的多种人类肿瘤系中癌症的启动和维持。在全球系统水平上，HSF1的功能允许细胞在恶性转化过程中发生的信号的剧烈失衡和DNA、蛋白质和能量代谢的深刻改变中存活下来。我们的研究表明，利用基因技术敲低HSF1的表达在正常细胞和整个动物体内具有良好的耐受性，但恶性细胞对这种“非癌基因”表现出深刻的依赖性，这是一种新的治疗机会。迄今为止，在发现这种创新靶点的抑制剂方面所做的努力相对有限。已报道的少数HSF1抑制剂表现出有限的特异性，对一般转录和翻译有显著影响，作用机制不明确。为了解决这一缺陷并开发HSF1功能的有效和选择性抑制剂，该项目将加入我们在热休克反应，实验治疗和癌症生物学方面的丰富经验，以及高通量筛选和化学探针优化方面的专业知识，目前可通过NIH分子文库探针生产中心网络获得，以实现以下具体目标：使用优化的高通量基于细胞的双报告试验确定HSF1的特异性抑制剂，这将在初步筛选过程中显着减少假阳性。目的2：利用二次筛选和反筛选试验评估化合物的效价、特异性和作用模式，以指导模拟物合成的筛选，并支持它们优化为有用的化学生物探针。为了验证我们的方法，我们已经在Broad研究所化学生物学平台上完成了一个试点筛选，使用了7万种已知的生物活性、小型药物样和纯化的天然产物。作为原理的证明，该筛选确定了一个家族的天然产物，专门抑制HSF1的激活。发现针对HSF1激活的不同机制调控步骤的其他抑制剂将揭示其在癌症生物学中的多方面作用，并将为广泛的人类癌症的化学预防和化疗的临床前研究提供重要的线索。

DESCRIPTION (provided by applicant): The heat shock response (HSR) is a powerful transcriptional program which acts genome-wide, not only to restore the normal protein folding environment through the induction of heat shock proteins but as more recent work has shown to re-shape global cellular pathways controlling survival, growth and metabolism. In mammals, this response is regulated primarily by Heat Shock Factor 1 (HSF1), a transcription factor whose mode of action has been conserved in broad outline across all eukaryotes. Surprisingly, our recent work has shown that the many beneficial effects of HSF1 known to enhance the survival of organisms under stress come at the cost of facilitating the initiation and maintenance of cancers in mouse models and diverse human tumor lines driven by a variety of underlying oncogenic lesions. Acting at a global systems level, HSF1 function permits cells to survive the drastic imbalances in signaling and profound alterations in DNA, protein and energy metabolism that occur during malignant transformation. A novel therapeutic opportunity has been highlighted by our demonstration that knockdown of HSF1 expression using genetic techniques is well tolerated in normal cells and whole animals but that malignant cells display a profound dependence on this "non-oncogene." Relatively limited efforts have been directed so far at discovering inhibitors of this innovative target. The few HSF1 inhibitors that have been reported demonstrate limited specificity with prominent effects on general transcription and translation and poorly defined mechanisms of action. To address this deficiency and develop potent and selective inhibitors of HSF1 function, this project will join our extensive experience in the heat shock response, experimental therapeutics and cancer biology with the expertise in high-throughput screening and chemical probe optimization now available through the NIH Molecular Libraries Probe Production Center Network to accomplish the following specific aims: Aim1: Identify specific inhibitors of HSF1 using an optimized high throughput cell-based dual reporter assay that will markedly reduce false positives during the primary screening process. Aim 2: Evaluate the potency, specificity and mode of action of compounds using secondary and counter-screening assays in order to guide the selection of screen hits for analog synthesis and support their optimization into useful chemical biological probes. To validate our approach, we have completed a pilot screen with the Broad Institute Chemical Biology Platform using a collection of 70,000 known bioactive, small drug-like and purified natural products. As proof of principle, this screen identified a family of natural products that specifically inhibit the activation of HSF1. The discovery of additional inhibitors that target HSF1 function at mechanistically distinct regulatory steps in its activation will shed light on its multifaceted role in cancer biology and will provide important leads for pre- clinical studies in the chemoprevention and chemotherapy of a wide range of human cancers. PUBLIC HEALTH RELEVANCE: Heat Shock Factor 1 (HSF1) is a multifaceted and powerful regulator of tumorigenesis and malignant progression. While normal cells are not dependent upon HSF1, tumor cells are critically dependent upon it for survival. Since no specific and potent inhibitors of this innovative target exist, we propose to identify chemical probe inhibitors of HSF1 to better understand the role of HSF1 in cancer and to serve as tools in the pre- clinical development of chemopreventative and chemotherapeutic agents.