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

基本信息

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
项目类别：
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

项目摘要

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.

项目概要远处转移的发生在乳腺癌死亡率中占很大比例； 30% 的早期诊断患者最终将发展为转移性疾病。转移进展的一步是细胞可塑性的增加，使一部分肿瘤细胞失去残留的上皮特征并获得迁移和侵袭行为，在分子上反映在上皮细胞中现在大量证据表明与癌症相关的 EMT 是一种高度相关的现象。播散性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）提出具有最大的攻击性、茎状行为潜力。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最近我们发现 RNA 聚合酶 (Pol II) 的局部调节仍不完全清楚。组蛋白甲基转移酶 SUV420H2 的暂停释放在稳定上皮细胞中起着重要作用乳腺癌细胞的“身份”，从而抑制乳腺癌细胞的发光入侵。发现 SUV420H2 将 H4K20me1 局部转换为 me3，通过阻断强制 RNA 聚合酶暂停 MOF/MSL 复合物的募集，这又是 H4K16 乙酰化所必需的，我们进一步发现 SUV420H2 介导的抑制限制了 pTEFb 和 Pol II 的释放。管腔乳腺上皮细胞中的间充质程序，但在 TGF-β 诱导的 EMT 后被定向到新的位点。 SUV420H2在三阴性/基础亚型乳腺癌中下调，且其强制下调或抑制促进 3D 生长的乳腺细胞球体的集体侵袭。这些和其他发现引导我们。提出 SUV420H2 介导的 Pol II 暂停控制的放松是表观遗传的来源之一可塑性和转录异质性是乳腺癌细胞适应和出现的基础结合使用精确连续测序 (Pro-seq) 和天然测序来检测具有侵袭性的肿瘤细胞。通过 CUT&Tag 技术进行染色质分析，我们将确定 SUV420H2 如何介导暂停约束增强了表型稳定性，以及这些约束的丧失如何导致转录混杂。我们将探讨 HEXIM1 / 7SK snRNP 复合物作为组蛋白 H4 修饰的新型“阅读器”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。转录多样性的动态暂停和具有侵入性“领导者”潜力的乳腺细胞的出现从长远来看，我们的研究结果将提供重要的集体入侵的 3D 球体模型。深入了解表观遗传可塑性的机制及其在肿瘤细胞适应中的作用，以及一个框架表彰其开发新的重编程策略来阻止乳腺癌转移进展。