The Bromodomain protein BRD4 controls HOTAIR, a long noncoding RNA essential for glioblastoma proliferation
The Bromodomain protein BRD4 controls HOTAIR, a long noncoding RNA essential for glioblastoma proliferation
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DOI：
10.1073/pnas.1424220112
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发表时间：
2015-07-07
影响因子：
11.1
通讯作者：
Wahlestedt, Claes
中科院分区：
文献类型：
--
作者：
Pastori, Chiara;Kapranov, Philipp;Wahlestedt, Claes
溴结构域和末端外（BET）结构域蛋白已成为胶质母细胞瘤和许多其他癌症中有希望的治疗靶点。BET溴结构域蛋白的小分子抑制剂减少多形性胶质母细胞瘤（GBM）进展所需的几种癌基因的表达。然而，BET蛋白抑制减少GBM生长的机制尚未完全了解。长链非编码RNA（lncRNA）是重要的表观遗传调节因子，在癌症起始和恶性进展中具有关键作用，但BET布罗莫结构域抑制剂对其表达和调节的机制洞察仍然难以捉摸。在这项研究中，我们使用Helicos单分子测序来全面分析GBM中差异表达的lncRNA，并且我们鉴定了一个GBM特异性lncRNA的子集，其表达受BET蛋白的调控。用BET溴结构域抑制剂I-BET 151处理GBM细胞降低了促肿瘤lncRNA HOX转录反义RNA（HOTAIR）的水平，并恢复了几种其他GBM下调lncRNA的表达。相反，HOTAIR的过表达与I-BET 151治疗联合消除了BET布罗莫结构域抑制剂的抗增殖活性。此外，染色质免疫沉淀分析证明了含溴结构域4（BRD 4）与HOTAIR启动子的结合，表明BET蛋白可以直接调节lncRNA表达。我们的数据揭示了BET蛋白控制胶质母细胞瘤细胞肿瘤生长的一种以前未被认识到的机制，并表明lncRNA网络的调节可能部分介导了目前在癌症和其他疾病临床试验中的许多表观遗传抑制剂的抗增殖作用。
Bromodomain and extraterminal (BET) domain proteins have emerged as promising therapeutic targets in glioblastoma and many other cancers. Small molecule inhibitors of BET bromodomain proteins reduce expression of several oncogenes required for Glioblastoma Multiforme (GBM) progression. However, the mechanism through which BET protein inhibition reduces GBM growth is not completely understood. Long noncoding RNAs (lncRNAs) are important epigenetic regulators with critical roles in cancer initiation and malignant progression, but mechanistic insight into their expression and regulation by BET bromodomain inhibitors remains elusive. In this study, we used Helicos single molecule sequencing to comprehensively profile lncRNAs differentially expressed in GBM, and we identified a subset of GBM-specific lncRNAs whose expression is regulated by BET proteins. Treatment of GBM cells with the BET bromdomain inhibitor I-BET151 reduced levels of the tumor-promoting lncRNA HOX transcript antisense RNA (HOTAIR) and restored the expression of several other GBM down-regulated lncRNAs. Conversely, overexpression of HOTAIR in conjunction with I-BET151 treatment abrogates the antiproliferative activity of the BET bromodomain inhibitor. Moreover, chromatin immunoprecipitation analysis demonstrated binding of Bromodomain Containing 4 (BRD4) to the HOTAIR promoter, suggesting that BET proteins can directly regulate lncRNA expression. Our data unravel a previously unappreciated mechanism through which BET proteins control tumor growth of glioblastoma cells and suggest that modulation of lncRNA networks may, in part, mediate the antiproliferative effects of many epigenetic inhibitors currently in clinical trials for cancer and other diseases.