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％的乳腺癌为ERα+，内分泌治疗是这些患者的标准治疗方法。 不幸的是，随着时间的流逝，对内分泌疗法的抵抗会发展出来，并且仍然是一个主要问题。原因 抗性尚不完全了解，但是异常的ERα激活是一个基本因素。因此，确定新的 ERα信号的组成部分和理解其在乳腺癌中的作用是治疗的巨大希望 ERα+癌症的尤其会受益于患有晚期和转移性肿瘤的患者 当前的内分泌疗法。我们的初步结果表明，染色质重塑蛋白富含 相互作用域4B（ARID4B）是ERα和ERα和 ARID4B的乳腺特异性消融抑制肿瘤发生。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 被放大，其表达在ERα+乳腺癌中升高。有趣的是，ERα+中的高芳基4b表达 （但不是ERα-）乳腺癌与癌症复发的风险增加和生存降低有关， 表明ARID4B参与了癌症的发展和抗治疗抗性。获得 对其功能的机械洞察力，初步结果表明，ARID4B被招募到 ERα靶基因远离确定的ERα结合增强子。此外，确定了DHX9 作为一种新型的ARID4B相互作用蛋白，参与ERα激活。 DHX9是NTP依赖性解旋酶 能够解决对产品转录抑制的转录耦合“ R环”。基于这些 调查结果，我们的中心假设是ARID4B激活ERα信号传导以促进肿瘤发生和 内分泌疗法抗性通过：（1）通过与ERα相互作用和（2）介导启动子循环循环 招募DHX9来解决启动子和增强子上的转录耦合的R环以促进产品 转录。在AIM 1中，ARID4B在肿瘤启动，癌症生长和内分泌治疗中的体内功能 在肿瘤定义模型中，将使用几个乳腺癌细胞（患者衍生）研究耐药性 PDX中的耐药性肿瘤和新生成的ARID4B敲入小鼠模型。在AIM 2中，我们将调查 ARID4B介导的增强子启动器循环如何调节ERα激活并确定重要功能 ARID4B上的域，可深入了解ARID4B-ERα和ARID4B-DHX9相互作用。 此外，我们将调查DHX9上启动子上“ R环”和增强子的分辨率是否为 激活ERα所必需的。最后，我们将证明针对ARID4B-DHX9轴的 抑制DHX9表达或活性抑制了肿瘤发生和对抗雌激素的抗性。我们的研究愿意 填补理解出现的功能和机制的关键差距 ARID4B并建立ARID4B-DHX9轴作为乳腺癌的治疗靶标。