IncRNA BORG Mediates Alternative Splicing to Enhance Cellular Plasticity in TNBC

IncRNA BORG 介导选择性剪接以增强 TNBC 中的细胞可塑性

• 批准号: 10350611
• 负责人: Kimberly Parker
• 金额: $ 1.25万
• 依托单位: CASE WESTERN RESERVE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2022-07-12
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10350611
• 关键词: Address; Alternative Splicing; Apoptotic; Automobile Driving; Behavior; Binding; Biopsy; Breast Cancer Patient; Breast cancer metastasis; Cancer Etiology; Cell Cycle Progression; Cell Survival; Cell physiology; Cells; Cessation of life; Chemoresistance; Complex; Data; Disease; Distal; Down-Regulation; ERBB2 gene; Enhancers; Epigenetic Process; Estrogen Receptors; Event; FDA approved; Frequencies; GADD45A gene; Gene Expression; Gene Silencing; Genes; Growth; Growth Factor Receptors; Health; Implant; In Vitro; Incidence; Individual; Knowledge; Laboratories; Ligase; Location; Mammospheres; Measures; Mediating; Modification; Molecular; Neoplasm Metastasis; Pathway interactions; Patient-Focused Outcomes; Phenotype; Play; Primary Neoplasm; Process; Progesterone Receptors; Prognosis; Proliferating; RNA Interference; RNA Splicing; Recurrence; Relapse; Ribonucleoproteins; Role; SRSF2 gene; Signal Transduction; Site; Spliced Genes; Stem Cell Development; Thromboplastin; Transcript; United States; Untranslated RNA; Variant; Woman; base; cancer stem cell; cancer subtypes; cell motility; differential expression; epigenome; epithelial to mesenchymal transition; in vitro Assay; in vivo; innovation; knock-down; malignant breast neoplasm; neoplastic; neoplastic cell; new therapeutic target; novel; programs; response; self-renewal; stem cell biomarkers; stem-like cell; stemness; targeted treatment; transcriptomics; triple-negative invasive breast carcinoma; tumor growth; tumorigenic

Project Summary/Abstract Breast cancer (BC) is the second leading cause of cancer-related deaths among women in the United States. A subset of BC called triple-negative breast cancer (TNBC) has the worst prognosis among BC subtypes, due to both the frequency and location of the resulting metastases. In TNBC, the underlying mechanisms that mediate metastatic outgrowth after disseminated tumor cells implant into distal sites is unknown. However, our laboratory recently identified the long noncoding RNA, BORG (BMP/OP-Response Gene), as a driver of TNBC metastasis. Indeed, BORG expression enhances neoplastic proliferation and chemoresistance, which are important cellular functions associated with metastatic phenotypes. Mechanistically, our group showed that BORG complexes with the E3 SUMO ligase TRIM28 in order to enhance neoplastic proliferation by repressing the expression of the growth arrest genes, p21 and gadd45a. Herein, I will show that the proliferative and cell survival pathways activated by BORG reflect breast cancer stem cell (BCSC) phenotypes. Importantly, I demonstrate that BORG enhances BCSC mammosphere formation and tumor growth both in vitro and in vivo, and that this phenotype relies in part on the formation of BORG:TRIM28 complexes. However, the mechanisms through which BORG and TRIM28 enhance BCSC plasticity are not yet understood. To this end, I find that BORG expression causes significant transcriptomic reprogramming, suggesting that BORG enhances cellular plasticity by mediating transcriptomic changes (e.g., alternative splicing) which broadly influences BCSC-like phenotypes. Accordingly, I showed that BORG expression plays a role in alternative splicing by upregulating 61 alternative splicing events (ASEs) and downregulating 83 ASEs, including a number of ASEs whose genes are involved in key metastatic pathways. Moreover, I determined that BORG downregulates the expression of 38 splicing factors, and up- regulates the expression of 6 splicing factors. Interestingly, the downregulation of 16 of these splicing factors relies upon BORG:TRIM28 complexes. Based on these preliminary data, I hypothesize that BORG:TRIM28 complexes drive BCSC plasticity and metastasis by regulating the epigenome and ASEs involved in metastatic phenotypes. To elucidate how BORG influences alternative splicing, I will (i) determine the mechanism(s) by which BORG:TRIM28 complexes regulate the expression and activity of splicing factors to drive variations in alternative splicing; and (ii) elucidate the consequences of BORG-induced ASEs on tumor cell plasticity and BCSC phenotypes. To our knowledge, my innovative analyses are the first to investigate the interaction between BORG and alternative splicing in promoting the metastatic features of TNBCs. By elucidating molecular mechanisms whereby BORG drives alternative splicing, we can better understand how lncRNAs elicit such drastic phenotypic changes to drive metastatic behaviors in TNBCs. Importantly, BORG-induced ASEs may provide new therapeu- tic targets to treat and alleviate metastatic TNBCs.

项目摘要/摘要 乳腺癌（BC）是美国女性与癌症相关死亡的第二大原因。一个 BC的子集称为三阴性乳腺癌（TNBC），在BC亚型中的预后最差 所得转移的频率和位置。在TNBC中，介导的基本机制 传播肿瘤细胞植入远端部位后的转移生长尚不清楚。但是，我们的实验室 最近将长的非编码RNA BORG（BMP/OP-RES-RESPONSE基因）确定为TNBC转移的驱动器。 实际上，Borg表达增强了肿瘤增殖和化学抗性，这是重要的细胞 与转移表型相关的功能。从机械上讲，我们的小组表明Borg复合物 使用E3 Sumo连接酶TRIM28，以通过抑制表达来增强肿瘤增殖 生长停滞基因P21和GADD45A。在此，我将证明增殖和细胞存活途径 由Borg激活反映乳腺癌干细胞（BCSC）表型。重要的是，我证明了博格 在体外和体内增强BCSC乳球的形成和肿瘤生长，并且这种表型 部分依赖于Borg：Trim28复合物的形成。但是，Borg的机制 TRIM28尚未了解BCSC可塑性。为此，我发现Borg表达原因 显着的转录组重编程，表明BORG通过介导转录组变化（例如替代剪接）来增强细胞可塑性，从而广泛影响BCSC样表型。因此，我 表明Borg表达通过上调61个替代剪接事件在替代剪接中起作用 （ASE）并下调83个ASE，包括许多基因参与关键转移的ASE 途径。此外，我确定Borg下调了38个剪接因子的表达，并上调了 调节6个剪接因子的表达。有趣的是，这些剪接因子中的16个下调 依靠Borg：Trim28复合物。基于这些初步数据，我假设Borg：Trim28 复合物通过调节表观基因组和涉及转移性的ASE驱动BCSC的可塑性和转移 表型。为了阐明博格如何影响替代剪接，我将（i）通过 哪个Borg：TRIM28复合物调节剪接因子的表达和活性，以驱动替代剪接的变化； （ii）阐明Borg诱导的ASE对肿瘤细胞塑性和BCSC的后果 表型。据我们所知，我的创新分析是第一个研究博格之间的相互作用的人 以及促进TNBC的转移特征的替代剪接。通过阐明分子机制 因此，Borg驱动替代剪接，我们可以更好地了解LNCRNA如何引起这种剧烈的表型 改变TNBC中转移行为的变化。重要的是，Borg引起的ASE可能会提供新的治疗 处理和减轻转移性TNBC的靶标。