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.

项目概要/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，随着时间的推移，内分泌治疗的耐药性逐渐形成，并且仍然是一个主要问题。 耐药性尚不完全清楚，但异常的 ERα 激活是一个潜在因素，因此，识别新的耐药性。 ERα 信号传导的组成部分并了解其在乳腺癌中的作用为治疗带来了巨大希望 ERα+ 癌症的治疗，尤其有利于患有难治性晚期和转移性肿瘤的患者 目前的内分泌疗法我们的初步结果表明染色质重塑蛋白AT丰富。 相互作用结构域 4B (ARID4B) 是 ERα 的重要转录共激活因子（不是共抑制因子） Arid4b 的乳腺特异性消融抑制肿瘤发生。 （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+ 乳腺癌中被扩增且表达升高。 （但不是 ERα-）乳腺癌与癌症复发风险增加和生存率降低相关， 表明 ARID4B 参与了癌症的发生和进展，从而获得治疗耐药性。 对其功能的机制深入了解，初步结果表明 ARID4B 被招募到启动子中 远离已鉴定的 ERα 结合增强子的 ERα 靶基因此外，还鉴定了 DHX9。 作为一种新型 ARID4B 相互作用蛋白，参与 ERα 激活，DHX9 是一种 NTP 依赖性解旋酶。 基于这些，能够解决抑制生产性转录的转录偶联“R-环”。 研究结果表明，我们的中心假设是 ARID4B 激活 ERα 信号传导以促进肿瘤发生和 通过以下方式产生内分泌治疗耐药：(1) 通过与 ERα 相互作用介导启动子增强子环路和 (2) 招募 DHX9 来解析启动子和增强子上的转录偶联 R 环，以促进生产力 在目标 1 中，ARID4B 在肿瘤发生、癌症生长和内分泌治疗中的体内功能。 将使用来自患者的肿瘤异种移植模型中的几种乳腺癌细胞来研究耐药性 在目标 2 中，我们将研究 PDX 中的耐药肿瘤和新生成的 ARID4B 敲入小鼠模型。 ARID4B 介导的增强子-启动子环如何调节 ERα 激活并识别重要的功能 ARID4B 上的域，以深入了解 ARID4B-ERα 和 ARID4B-DHX9 相互作用。 此外，我们将研究 DHX9 对启动子和增强子上“R 环”的解析是否正确 最后，我们将证明通过靶向 ARID4B-DHX9 轴。 抑制 DHX9 表达或活性会抑制肿瘤发生和抗雌激素耐药性。 填补了理解新兴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。