The role of novel oncogenic histone H3 lysine variants in defining a therapeutically actionable epigenetic signature

项目摘要/摘要 将有170多万人被诊断为癌症，将有60万人死于癌症 2020年在美国。投入资源开发工具和试剂，以确定致癌机制和 将这一知识应用于治疗剂和诊断工具的开发显然需要 改善患者的预后。最近的研究已经确定了与癌症相关的氨基酸替换 在进化上保守的组蛋白中，导致了术语“肿瘤组蛋白”。这类变化的例子 与癌症相关的基因包括H3K27M、H3G34V/R/D和H3K36M。而这些细胞的致癌机制 突变各不相同，每个氨基酸的变化都会扰乱组蛋白甲基化的格局，影响转录 监管。了解癌组织蛋白如何改变基因表达可以提供关键的治疗洞察力。 表达H3K27M的胶质瘤中组蛋白甲基化格局的改变导致多巴胺受体D2 (DRD2)过表达，这些肿瘤对DRD2和/或CLPP拮抗剂ONC201有反应。这个例子 强调与癌症相关的表观遗传学变化如何揭示潜在的可药物靶点。 在我们的初步研究中，我们发现了一系列显性的H3突变，命名为X到K(R42K， E50K，Q68K，E73K)，其中野生型氨基酸转变为赖氨酸，在30多名患者的肿瘤中 乳腺癌和其他癌症。初步的体外实验表明，X到K突变促进了转化； H3X to K突变产生真正的癌组蛋白的一个主要指标。然而，这两个X到K 氨基酸的变化改变了这些组蛋白的功能和X到K原癌组蛋白的机制(S) 产生致癌表型尚不清楚。我们假设H3X到K的变化赋予致癌作用 通过(1)引入改变核小体完整性和/或功能的局部结构变化的性质 和/或(2)为染色质修饰剂引入新的底物，从而支持一种新的，以及 潜在的目标，基因表达程序。利用Emory/Winship的集成环境， 我们提出了一种协作的多PI方法来验证我们的假设，目的如下：目标1)检查 H3X到K氨基酸的改变对组蛋白功能以及细胞和肿瘤生长的影响；目的2) 确定组蛋白中X到K氨基酸的变化如何改变基因表达。重要的是，拟议的研究表明 为定义新的癌症标志物和可用药靶点奠定基础。我们的跨学科团队是 唯一有资格执行拟议的临床前研究，这些研究与以下方面的进展直接相关 癌症治疗和诊断。我们研究的长期目标是开发用于检测的诊断工具 并在患者肿瘤中确定可操作的表观遗传学特征 以这些H3X到K癌基因突变为特征。

PROJECT SUMMARY/ABSTRACT Over 1.7 million individuals will be diagnosed with cancer and 600,000 cancer-associated deaths will occur in the US in 2020. Devoting resources to develop tools and reagents to define mechanisms of oncogenicity and applying this knowledge to the development of therapeutic agents and diagnostic tools is clearly required to improve patient outcome. Recent research has identified cancer-associated amino acid substitutions that occur in the evolutionarily conserved histone proteins, leading to the term “oncohistones.” Examples of such changes linked to cancer include H3K27M, H3G34V/R/D, and H3K36M. While the mechanism of oncogenicity for these mutations varies, each amino acid change perturbs the histone methylation landscape, affecting transcriptional regulation. Understanding how oncohistones alter gene expression can provide critical therapeutic insight. Changes to the histone methylation landscape in H3K27M-expressing gliomas result in dopamine receptor D2 (DRD2) overexpression and these tumors respond to the DRD2 and/or CLPP antagonist ONC201. This example highlights how cancer-associated epigenetic changes can unmask potentially druggable targets. In our preliminary studies, we have identified a series of dominant H3 mutations, termed X to K (R42K, E50K, Q68K, E73K), in which the wildtype amino acid is changed to a lysine, in more than 30 patient tumors in breast and other cancers. Preliminary in vitro experiments suggest that X to K mutation promotes transformation; a major indicator that H3 X to K mutations produce bona-fide oncohistones. However, both how these X to K amino acid changes alter the function of these histones and the mechanism(s) by which X to K oncohistones produce oncogenic phenotypes is unclear. We hypothesize that H3 X to K changes confer oncogenic properties by (1) introducing localized structural changes that alter nucleosome integrity and/or function and/or (2) introducing a new substrate for chromatin modifiers, thereby supporting a novel, and potentially targetable, gene expression program. Drawing on the integrated environment at Emory/Winship, we propose a collaborative multi-PI approach to test our hypothesis through the following aims: Aim 1) Examine the impact of H3 X to K amino acid changes on histone function together with cell and tumor growth; and Aim 2) Define how X to K amino acid changes in histones alter gene expression. Importantly, the proposed studies lay the groundwork for defining both new cancer signatures and druggable targets. Our interdisciplinary team is uniquely qualified to perform the proposed preclinical studies, which are directly related to advancements in cancer treatment and diagnosis. The long-term goal of our studies is to develop diagnostic tools for the detection of oncohistone-associated tumors and identify a therapeutically actionable epigenetic signature in patient tumors characterized by these H3 X to K oncogenic mutations.