Relaxed Polymerase Pausing as a Driver of Epigenetic Plasticity and Cancer Cell Invasion

松弛的聚合酶暂停是表观遗传可塑性和癌细胞侵袭的驱动因素

• 批准号: 10600087
• 负责人: Paula M. Vertino
• 金额: $ 40.91万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10600087
• 关键词: 3-Dimensional; Acetylation; Automobile Driving; Behavior; Binding; Biological Assay; Breast; Breast Cancer Cell; Breast Epithelial Cells; Cell Maintenance; Cells; Characteristics; Chemoresistance; Chromatin; Complex; DNA Packaging; DNA-Directed RNA Polymerase; Deposition; Development; Diagnosis; Disease; Distant Metastasis; Down-Regulation; Environment; Epigenetic Process; Epithelium; Exhibits; Gene Expression; Genes; Genetic Transcription; Goals; Heterogeneity; Histone H4; Hybrids; Invaded; Malignant Neoplasms; Mediating; Mesenchymal; Metastatic breast cancer; Methylation; Modeling; Modification; Molecular; Patients; Phenotype; Play; Polymerase; Primary Neoplasm; Process; Property; RNA; RNA Polymerase II; Reader; Regulation; Relaxation; Repression; Residual state; Role; Running; Site; Small Nuclear Ribonucleoproteins; Solid Neoplasm; Source; Tail; Technology; Testing; Therapeutic Intervention; Transcriptional Regulation; Transforming Growth Factor beta; Variant; Woman; cancer cell; cancer survival; chemical stability; epigenetic memory; epigenetic variation; epigenome; epigenome editing; epithelial to mesenchymal transition; flexibility; genome-wide; histone methyltransferase; insight; malignant breast neoplasm; mortality; neoplastic cell; novel; packaging material; posttranscriptional; programs; promoter; recruit; response; stem; stem-like cell; transcription factor; transcriptional reprogramming; triple-negative invasive breast carcinoma

Project Summary The development of distant metastases accounts for a significant proportion of breast cancer mortality; as many as 30% of patients initially diagnosed at an early stage will eventually progress to metastatic disease. A key early step in metastatic progression is an increase in cellular plasticity that enables a subset of tumor cells to lose residual epithelial features and gain migratory and invasive behavior, molecularly reflected in the epithelial to mesenchymal transition (EMT). Considerable evidence now points to cancer-associated EMT as a highly dynamic and reversible process with disseminated cancer cells exhibiting many hybrid intermediate states (partial-EMT) proposed to possess the greatest potential for aggressive, stem-like, behavior. However, the epigenetic mechanisms that control such phenotypic plasticity and the role of this process in early invasion remain incompletely understood. Recently we discovered that the local regulation of RNA polymerase (Pol II) pause release by the histone methyltransferase SUV420H2 plays an important role in stabilizing the epithelial ‘identity’ of luminal breast cancer cells and in so doing, suppresses breast cancer cell invasion. Specifically, we find that the local conversion of H4K20me1 to me3 by SUV420H2 enforces RNA polymerase pausing by blocking recruitment of the MOF/MSL complex, which is in turn necessary for the acetylation of H4K16, recruitment of pTEFb and Pol II pause release. We further find that SUV420H2-mediated repression constrains the mesenchymal program in luminal breast epithelial cells, yet is directed to new sites upon TGF-β induced EMT. SUV420H2 is downregulated in triple negative/basal subtype of breast cancers, and its forced downregulation or inhibition promotes collective invasion in breast cell spheroids grown in 3D. These and other findings lead us to propose that the relaxation of SUV420H2-mediated Pol II pausing control is one source of the epigenetic plasticity and transcriptional heterogeneity that underlies breast cancer cell adaptation and the emergence of tumor cells with invasive properties. Using a combination of precision run-on sequencing (Pro-seq) and native chromatin analyses via CUT&Tag technology, we will determine the how the SUV420H2 mediated pause constraints enforces phenotypic stability and how loss of these constraints allows for transcriptional promiscuity. We will explore the role of the HEXIM1 / 7SK snRNP complex as a novel ‘reader’ of histone H4 modifications and its role in SUV420H2-mediated pause control. Lastly, we will determine the impact of dysregulated Pol II pausing dynamics on transcriptional diversity and the emergence of breast cells with invasive “leader” potential in a 3D spheroid model of collective invasion. Over the long term, the results of our studies will provide important insight into the mechanisms underlying epigenetic plasticity and its role in tumor cell adaptation, and a framework for the development of novel reprogramming strategies to block breast cancer metastatic progression.

项目摘要 遥远转移的发展占乳腺癌死亡率的很大比例。就像许多 由于最初在早期诊断的患者中有30％最终会发展为转移性疾病。较早的关键 转移性进展的一步是细胞可塑性的增加，使肿瘤细胞的一部分能够失去 残留的上皮特征并获得迁移和侵入性行为，分子反映在上皮中 间充质转变（EMT）。现在有大量证据表明与癌症相关的EMT是高度 传播癌细胞表现出许多混合中间状态的动态和可逆过程 （部分EMT）提议具有侵略性，类似茎状行为的最大潜力。但是， 控制这种表型可塑性的表观遗传机制以及该过程在早期入侵中的作用 保持不完全理解。最近，我们发现RNA聚合酶的局部调节（POL II） 组蛋白甲基转移酶SUV420H2暂停释放在稳定上皮方面起着重要作用 腔乳腺癌细胞的“身份”，因此，抑制了乳腺癌细胞的侵袭。具体来说，我们 发现SUV420H2将H4K20me1局部转换为ME3，通过阻断RNA聚合酶暂停 MOF/MSL复合物的招募，而H4K16的乙酰化又是必需的 PTEFB和Pol II暂停释放。我们进一步发现SUV420H2介导的表示构成了 腔乳房上皮细胞中的间充质程序，但在TGF-β诱导的EMT时针对新部位。 SUV420H2以乳腺癌的三重阴性/基底亚型下调，其强制下调 或抑制作用促进在3D中生长的乳腺细胞球体中的集体侵袭。这些和其他发现带领我们 提出SUV420H2介导的Pol II暂停控制的放松是表观遗传学的来源之一 乳腺癌细胞适应和出现的可塑性和转录异质性 具有侵入性特性的肿瘤细胞。结合精密跑步测序（Pro-Seq）和本机的组合 染色质通过剪切和标签技术进行分析，我们将确定SUV420H2介导的暂停方式 约束实施表型稳定性以及这些约束的损失如何允许转录滥交。 我们将探讨Hexim1/7sk SNRNP复合物作为组蛋白H4修饰的新型“读取器”的作用 及其在SUV420H2介导的暂停控制中的作用。最后，我们将确定失调的Pol II的影响 暂停转录多样性的动态和具有侵入性“领导者”潜力的乳腺细胞的出现 在集体入侵的3D球体模型中。从长远来看，我们的研究结果将提供重要 深入了解表观可塑性的基础机制及其在肿瘤细胞适应中的作用和框架 为了开发新的重编程策略，以阻止乳腺癌转移性进展。