Development of p300/CBP histone acetyltransferase inhibitors for oncogene-driven cancers

项目总结： 癌基因突变经常通过不适当的调节激活来推动恶性转化 激酶和干扰致癌基因磷酸化的抑制剂已经改变了对癌症亚类的护理 病人。尽管取得了这些成功，但在已知的癌基因中，激酶只是一小部分。尤其是，有几个 转录因子癌基因对肿瘤的发生、发展和维持至关重要。在少数情况下， 靶向转录因子癌基因，如雌激素、雄激素和维甲酸受体，已导致 临床上有意义的反应。然而，大多数转录因子的直接靶向已被证明具有挑战性。 直接靶向致癌转录因子的另一种方法是抑制上游表观遗传 染色质状态的调节机制。事实上，许多表观遗传调节因子是反复发生的体细胞突变， 一些针对染色质调节剂的小分子已经被证明可以阻止肿瘤的生长。在……里面 初步研究，我们进行了一项基于基因表达的筛查，以确定抑制 前列腺癌中转录异常的融合癌基因TMPRSS2-ERG的活性及鉴定 BRD4683，p300和CREB结合蛋白(CBP)组蛋白乙酰转移酶(HAT)的高效抑制剂 活动。我们已经解决了BRD4683与p300的复合体的结构，并证实了对BRD4683的抑制作用 P300/CBP HAT活性是转录因子驱动的人类癌细胞株生存所特需的。 尽管BRD4683是一种有用的工具化合物，但它有几种化学缺陷，限制了它在 药物开发。 因此，我们使用BRD4683开发并验证了高通量和高性价比的生化筛选器 为了发现更多新的小分子p300/CBP HAT抑制剂以及一系列后续研究- 消除假阳性并优先处理化学上易处理的分子的分析。在这个项目中，我们建议 发现新的p300/CBP抑制剂并系统地鉴定依赖于联合 P300/CBP HAT活动。在目标1中，我们将进行超过80万的高通量生化筛查 用于鉴定新的p300/CBP HAT抑制剂的化合物。在目标2中，我们将验证新的p300/CBP候选基因 鉴定抑制剂的三种互补检测方法的IC50至少为10微米。这些检测方法不仅可以确认 抑制剂的特异性，但也将验证细胞中的生化活性。在目标3中，我们将进行迭代医疗 化学，目标是确定领先的候选人。在这些研究的同时，我们将进行两种化学 以及系统地识别依赖于细胞p300/CBP HAT活性的肿瘤亚型的基因实验 健身(目标4)。 为了进行这些研究，我们组建了一个多学科的研究团队， 在癌症生物学、结构生物学、药物化学和药物开发方面的经验和专业知识。我们 预计这些研究将使我们能够确定将作为主要候选者的小分子 刺激临床等级p300/CBP HAT抑制剂的开发，并确定哪些患者可能 从这些抑制剂中获益。

Project Summary: Oncogene mutations frequently drive malignant transformation through inappropriate activation of regulatory kinases, and inhibitors that disrupt oncogenic phosphorylation have transformed care for subsets of cancer patients. Despite these successes, kinases are a small fraction of known oncogenes. In particular, several transcriptional factor oncogenes are essential for tumor initiation, progression and maintenance. In a few cases, targeting transcription factor oncogenes, such as estrogen, androgen and retinoic acid receptors, has led to clinically meaningful responses. However, direct targeting of most transcription factors has proven challenging. An alternative approach to directly targeting oncogenic transcription factors is to inhibit upstream epigenetic mechanisms regulating chromatin state. Indeed, many epigenetic regulators are recurrently somatically mutated, and several small molecules targeting chromatin regulators have been shown to abrogate tumor growth. In preliminary studies, we performed a gene expression-based screen to identify small molecules that inhibit the activity of TMPRSS2-ERG, a fusion oncogene leading to aberrant transcription in prostate cancer, and identified BRD4683, a highly potent inhibitor of p300 and CREB binding protein (CBP) histone acetyl transferase (HAT) activity. We have solved the structure of BRD4683 in complex with p300 and confirmed that inhibition of p300/CBP HAT activity is specifically required for survival of transcription factor-driven human cancer cell lines. Despite serving as a useful tool compound, BRD4683 has several chemical liabilities that limit its potential for drug development. We thus used BRD4683 to develop and validate a high-throughput and cost-effective biochemical screen for discovery of additional novel small molecule p300/CBP HAT inhibitors as well as a cascade of follow up- assays to eliminate false positives and prioritize chemically tractable molecules. In this project, we propose to identify new p300/CBP inhibitors and to systematically identify tumor subtypes dependent on combined p300/CBP HAT activity. In Aim 1, we will perform a high throughput biochemical screen of more than 800,000 compounds to identify new p300/CBP HAT inhibitors. In Aim 2, we will validate novel p300/CBP candidates using three complementary assays to identify inhibitors an IC50 of at least 10 µM. These assays will not only confirm inhibitor specificity but will also validate biochemical activity in cells. In Aim 3, we will perform iterative medicinal chemistry with the goal of identifying lead candidates. In parallel to these studies, we will perform both chemical and genetic experiments to systematically identify tumor subtypes that depend on p300/CBP HAT activity for cell fitness (Aim 4). To perform these studies, we have assembled a multidisciplinary research team with the necessary experience and expertise in cancer biology, structural biology, medicinal chemistry and drug development. We anticipate that these studies will allow us to identify small molecules that will serve as lead candidates that will spur the development of clinical grade p300/CBP HAT inhibitors and define which patient populations are likely to benefit from such inhibitors.