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)是美国女性癌症相关死亡的第二大原因。一个 被称为三阴性乳腺癌(TNBC)的BC亚型在BC亚型中预后最差，原因是 转移的频率和位置。在TNBC中，调解的基本机制 播散性肿瘤细胞植入远端部位后的转移性生长尚不清楚。然而，我们的实验室 最近发现的BMP/OP反应基因(BMP/OP-Response gene，BMP/OP-Response gene)是肿瘤转移的驱动因子。 事实上，Borg的表达增强了肿瘤的增殖和化疗耐药性，这是重要的细胞 与转移表型相关的功能。从机制上讲，我们的团队证明了博格复合体 通过抑制E3相扑连接酶TRIM28的表达来促进肿瘤的增殖 生长受阻基因p21和gadd45a。在这里，我将展示增殖和细胞生存途径 Borg激活反映乳腺癌干细胞(BCSC)的表型。重要的是，我证明了博格 在体外和体内都能促进BCSC乳房的形成和肿瘤的生长，并且这种表型 部分依赖于Borg：TRIM28络合物的形成。然而，博格通过的机制 而TRIM28增强BCSC的可塑性尚不清楚。为此，我发现博格的表达导致了 显著的转录重编程，表明Borg通过介导广泛影响BCSC样表型的转录变化(例如，选择性剪接)来增强细胞可塑性。因此，我 结果表明，Borg表达通过上调61个选择性剪接事件在选择性剪接中发挥作用 (ASES)和下调83个ASE，其中包括一些其基因参与关键转移的ASE 小路。此外，我确定博格下调了38个剪接因子的表达，并上调了- 调节6种剪接因子的表达。有趣的是，其中16个剪接因子的下调 依赖于博格：TRIM28复合体。根据这些初步数据，我假设博格：TRIM28 复合体通过调节表观基因组和参与转移的ASES来驱动BCSC的可塑性和转移 表型。为了阐明博格如何影响选择性剪接，我将(I)通过以下方式确定机制(S) 哪些Borg：TRIM28复合体调节剪接因子的表达和活性以驱动选择性剪接的变异；以及(Ii)阐明Borg诱导的ASES对肿瘤细胞可塑性和BCSC的影响 表型。据我们所知，我的创新分析是第一次调查博格人之间的互动 选择性剪接促进TNBCs的转移特征。通过阐明分子机制 通过博格驱动选择性剪接，我们可以更好地理解lncRNA是如何引发如此剧烈的表型的 改变以驱动TNBCs的转移行为。重要的是，博格人诱导的ASES可能提供新的治疗方法-- TIC的靶点是治疗和缓解转移的TNBCs。