Non-coding RNAs for Epigenetic Transcriptional Silencing in Prostate Cancer

描述（由申请人提供）：前列腺癌在75岁之前折磨四分之一的男性，并且仍然是美国的主要公共卫生问题。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，特别是人类前列腺癌中表观遗传基因转录的基本分子机制。我们专注于Polycomb抑制复合物（PRCs）在INK 4a/ARF基因座的转录控制中的作用，其基因产物是癌基因诱导衰老的主要介质。PRC介导的基因沉默是由组蛋白H3赖氨酸27（H3 K27 me）在染色质中的靶基因座处的甲基化介导的，所述甲基化由PRC 2的赖氨酸甲基转移酶EZH 2启动，随后H3 K27 me通过结合至染色体盒（CBX）蛋白而与PRC 1缔合，导致染色质浓缩和靶基因沉默。我们最近的研究表明，PRC 1对INK 4a/ARF基因座的沉默活性需要CBX 7与非编码RNA转录本ANRIL（INK 4a基因座的反义RNA）和H3 K27 me通过其保守的chromodomain相互作用，突出了长非编码RNA在表观遗传转录沉默中的直接作用。通过抑制INK 4a/ARF基因座在细胞寿命延长中发挥关键作用的PRC的CBX 7和其他关键组分在前列腺癌中过表达。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、CBX 7和EZH 2的表达显著升高，而p16 Ink 4a的表达相应降低。然而，非编码RNA在PRC介导的基因沉默中的分子机制尚不清楚。在这个项目中，我们的目标是确定非编码RNA和H3 K27 me在正常前列腺上皮细胞中的PRCs基因沉默中的功能相互作用的分子基础，以及在前列腺上皮内瘤变转化为前列腺癌的过程中，使用染色质/细胞生物学和结构/化学生物学相结合的方法。我们期望我们的研究结果，包括新型化学工具，将对更好地理解前列腺癌生物学和未来人类前列腺癌预后和预防治疗手段的进步产生深远影响。

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.