Molecular Function and Mechanism of ARID4B in ERalpha Signaling and Breast Cancer

ARID4B 在 ERalpha 信号传导和乳腺癌中的分子功能和机制

• 批准号: 10522358
• 负责人: Ray-Chang Wu
• 金额: $ 40.78万
• 依托单位: GEORGE WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-02 至 2027-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10522358
• 关键词: ARID Domain; ARID4B gene; Ablation; Address; Advanced Malignant Neoplasm; Aromatase Inhibitors; Biological Process; Biology; Breast Cancer Cell; Breast Cancer Treatment; ChIP-seq; Coupled; DNA; Development; Disease; Disseminated Malignant Neoplasm; ESR1 gene; Enhancers; Estrogen Antagonists; Estrogen Receptor alpha; Estrogen Therapy; Estrogens; Genes; Genetic Transcription; Growth; Human; Hybrids; Intervention; Investigation; Knock-in Mouse; Knock-out; Malignant Neoplasms; Mammary gland; Mediating; Medical; Metastatic breast cancer; Molecular; Mutation; Neoplasm Metastasis; Oncogenic; Pathway interactions; Patients; Pharmacology; Proteins; Public Health; RNA; Refractory; Relapse; Repressor Proteins; Research; Resistance; Resolution; Role; Series; Signal Pathway; Signal Transduction; Testing; The Cancer Genome Atlas; Time; Transcription Coactivator; Transcription Regulatory Protein; Xenograft Model; base; cancer cell; cancer initiation; cancer recurrence; cancer risk; cancer stem cell; chromatin remodeling; clinically relevant; cohort; genetic corepressor; genome-wide; genomic data; helicase; hormone therapy; in vivo; inhibitor; insight; knock-down; malignant breast neoplasm; mortality; mouse model; mutant; novel; patient derived xenograft model; promoter; recruit; refractory cancer; retinoblastoma binding protein 1; standard care; stem-like cell; therapeutic target; therapy development; therapy resistant; transcriptome; tumor; tumor initiation; tumor progression; tumor xenograft; tumorigenesis

Project Summary/Abstract Over 70% of breast cancer are ERα+ and endocrine therapy is the standard treatment for these patients. Unfortunately, resistance to endocrine therapy develops over time and remains a major problem. The cause for resistance is not fully understood, but aberrant ERα activation is an underlying factor. Therefore, identifying new component of the ERα signaling and understanding its role in breast cancer holds a great promise for treatment of ERα+ cancer and will particularly benefit patients with advanced and metastatic tumors that are refractory to current endocrine therapies. Our preliminary results showed that chromatin remodeling protein AT-rich interaction domain 4B (ARID4B) is an essential transcription co-activator (not a co-repressor) for ERα and mammary gland-specific ablation of Arid4b inhibits tumorigenesis. Analyses of large-scale genomic datasets (TCGA and other breast cancer cohorts), genome-wide transcriptome, and IHC analyses showed that ARID4B is amplified and its expression elevated in ERα+ breast cancer. Interestingly, high ARID4B expression in ERα+ (but not ERα-) breast cancers is associated with increased risk of cancer recurrence and decreased survival, suggesting that ARID4B is involved in the cancer development and progression to therapy resistance. To gain mechanistic insight into its function, preliminary results revealed that ARID4B is recruited to the promoters of ERα target genes that are far away from the identified ERα-bound enhancers. In addition, DHX9 was identified as a novel ARID4B-interacting protein and is involved in ERα activation. DHX9 is an NTP-dependent helicase capable of resolving transcription-coupled ‘R-loops’ that is inhibitory to productive transcription. Based on these findings, our central hypothesis is that ARID4B activates ERα signaling to promote tumorigenesis and endocrine therapy resistance by: (1) mediating promoter-enhancer looping via interaction with ERα and (2) by recruiting DHX9 to resolve the transcription-coupled R-loops on promoters and enhancers to promote productive transcription. In Aim 1, the in vivo function of ARID4B in tumor initiation, cancer growth, and endocrine therapy resistance will be investigated using several breast cancer cells in tumor xenograft models, patient-derived resistant tumors in PDX, and a newly generated ARID4B knock-in mouse model. In Aim 2, we will investigate how ARID4B-mediated enhancer-promoter looping regulates ERα activation and identify the important functional domain(s) on ARID4B to provide in-depth understanding of ARID4B-ERα and ARID4B-DHX9 interactions. Furthermore, we will investigate whether resolution of “R-loops” on the promoter and enhancer by DHX9 is required for the activation of ERα. Finally, we will demonstrate that targeting the ARID4B-DHX9 axis by suppressing DHX9 expression or activity inhibits tumorigenesis and resistance to antiestrogens. Our study will fill the crucial gap in understanding the function and mechanism underlying the emerging oncogenic activity of ARID4B and establish ARID4B-DHX9 axis as a therapeutic target for breast cancer.

项目摘要/摘要 超过70%的乳腺癌是ERα+，内分泌治疗是这些患者的标准治疗方法。 不幸的是，内分泌治疗的抵抗力随着时间的推移而发展，并且仍然是一个主要问题。其原因是 耐药性尚不完全清楚，但ERα的异常激活是一个潜在的因素。因此，识别新的 ERα信号的组成及其在乳腺癌中的作用的理解为治疗带来了希望 ERα+癌症，并将特别有利于晚期和转移性肿瘤患者，这些肿瘤对 目前的内分泌疗法。我们的初步结果显示染色质重塑蛋白AT-丰富 相互作用结构域4B(ARID4B)是ER-α和ER的重要转录共激活因子(而不是共抑制因子) 乳腺特异的Arid4b消融抑制肿瘤的形成。大规模基因组数据集的分析 (TCGA和其他乳腺癌队列)、全基因组转录组和IHC分析表明ARID4B 在ERα+乳腺癌中扩增并表达上调。有趣的是，ARID4B在ERα+中的高表达 (但不是ERα-)乳腺癌与癌症复发风险增加和生存率下降有关， 提示ARID4B参与了肿瘤的发生和发展到治疗耐药的过程。为了获得 对其功能的机械论洞察，初步结果显示ARID4B被招募到启动子 ERα靶向远离已确定的ERα结合增强子的基因。此外，还鉴定了DHX9 作为一种新的ARID4B相互作用蛋白，参与ERα的激活。DHX9是一种依赖NTP的解旋酶 能够分解抑制生产转录的转录偶联‘R-环’。基于这些 我们的中心假设是ARID4B激活ERα信号以促进肿瘤的发生和发展 内分泌治疗抵抗：(1)通过与ERα的相互作用介导启动子-增强子环和(2)通过 招募DHX9解决启动子和增强子上的转录偶联R环以促进生产力 抄写。在目标1中，ARID4B在肿瘤发生、肿瘤生长和内分泌治疗中的体内功能 将在患者来源的肿瘤异种移植模型中使用几种乳腺癌细胞来研究耐药性 PDX中的耐药肿瘤，以及新产生的ARID4B敲入小鼠模型。在目标2中，我们将调查 ARID4B介导的增强子-启动子环如何调节ERα的激活并识别重要的功能 关于ARID4B的域名(S)，以提供对ARID4B-ERα和ARID4B-DHX9相互作用的深入了解。 此外，我们还将研究DHX9对启动子和增强子上的R-环的拆分是否 激活ERα所需的。最后，我们将演示通过以下方式将ARID4B-DHX9轴作为目标 抑制DHX9的表达或活性可以抑制肿瘤的发生和对抗雌激素的耐药性。我们的研究将 填补在理解新出现的致癌活性的功能和机制方面的关键空白 ARID4B并建立ARID4B-DHX9轴作为乳腺癌的治疗靶点。