Non-coding RNAs for Epigenetic Transcriptional Silencing in Prostate Cancer

描述（由申请人提供）：前列腺癌折磨着四分之一的75岁男性，在美国仍然是一个主要的公共卫生问题。尽管在疾病诊断和治疗方面取得了一些成功，但影响前列腺上皮内瘤变向前列腺癌转变的分子参数仍然难以捉摸。我们研究的长期目标是确定人类生物学和疾病中表观遗传基因转录的基本分子机制，特别是人类前列腺癌。我们关注多梳抑制复合物（PRCs）在INK4a/ARF基因座转录控制中的作用，INK4a/ARF基因座的基因产物是致癌基因诱导衰老的主要介质。prc导向的基因沉默是通过染色质靶位点的组蛋白H3赖氨酸27 （H3K27me）甲基化介导的，该甲基化由PRC2的赖氨酸甲基转移酶EZH2启动，随后H3K27me通过结合色盒（CBX）蛋白与PRC1结合，导致染色质凝聚和靶基因沉默。我们最近的研究表明，PRC1对INK4a/ARF基因座的沉默活性需要CBX7通过其保守的色域与非编码RNA转录物ANRIL （INK4a基因座的反义rna）和H3K27me相互作用，突出了长链非编码RNA在表观遗传转录沉默中的直接作用。CBX7和其他通过抑制INK4a/ARF基因座在细胞寿命延长中发挥关键作用的PRCs的关键成分在前列腺癌中过度表达。在我们的研究中，我们进一步观察到与正常前列腺上皮细胞相比，前列腺癌中ANRIL、CBX7和EZH2的表达显著升高，p16Ink4a的表达相应降低。然而，非编码RNA在prc定向基因沉默中的分子机制尚不清楚。在这个项目中，我们的目标是利用染色质/细胞生物学和结构/化学生物学相结合的方法，确定非编码RNA和H3K27me在正常前列腺上皮细胞中被prc基因沉默以及前列腺上皮内瘤变转化为前列腺癌过程中功能相互作用的分子基础。我们期望我们的研究成果，包括新的化学工具，将对更好地了解前列腺癌生物学和未来治疗手段的发展，对人类前列腺癌的预后和预防产生深远的影响。

DESCRIPTION (provided by applicant): Prostate cancer afflicts 1 in 4 men by the age of 75 and remains a major public health concern in the United States. Despite some success in disease diagnosis and treatment the molecular parameters that influence the transition from prostatic intraepithelial neoplasia to prostate cancer has remained elusive. The long-term goal of our research is to determine the fundamental molecular mechanisms of epigenetic gene transcription in human biology and disease, particularly human prostate cancer. We focus on the role of Polycomb repressive complexes (PRCs) in transcriptional control of the INK4a/ARF locus, gene products of which are the primary mediators of oncogene-induced senescence. PRC-directed gene silencing is mediated by methylation of histone H3 lysine 27 (H3K27me) at target loci in chromatin that is initiated by the lysine methyltransferase EZH2 of the PRC2 and followed by H3K27me association with the PRC1 by binding to chromobox (CBX) proteins, resulting in chromatin condensation and target gene silencing. Our recent study reveals that the silencing activity of PRC1 for the INK4a/ARF locus requires CBX7 interactions with a non-coding RNA transcript ANRIL (the antisense RNA of INK4a locus) and H3K27me via its conserved chromodomain, highlighting a direct role of long non-coding RNA in epigenetic transcriptional silencing. CBX7 and other key components of PRCs that play a key role in cellular lifespan extension by repressing the INK4a/ARF locus are over-expressed in prostate cancer. We further observed in our study markedly elevated expression of ANRIL, CBX7 and EZH2 and a corresponding decrease in p16Ink4a expression in prostate cancer as compared to normal prostate epithelial cells. However, the molecular mechanism of non-coding RNA in PRC-directed gene silencing is not clear. In this project, we aim to determine the molecular underpinning of the functional interplay between non-coding RNA and H3K27me in gene silencing by the PRCs in normal prostate epithelial cells, as well as during the conversion of prostatic intraepithelial neoplasia into prostate carcinoma using combined chromatin/cell biology and structural/chemical biology methods. We expect that the results emerging from our studies including novel chemical tools will have profound impact on a better understanding of prostate cancer biology and future advance of therapeutic means for prognosis and prevention of human prostate cancer. PUBLIC HEALTH RELEVANCE: Non-coding RNA transcripts play a fundamental role in epigenetic control of gene expression in the human genome, but the underlying molecular mechanism has remained elusive. In this project we will investigate how non-coding RNAs function as the molecular circuitry to regulate the epigenetic character of the human genome. The outcome of our study is expected to provide a new understanding of the role of ncRNAs to guide the Polycomb group proteins that govern the epigenome state of human biology of health and disease, particularly prostate cancer.