LSUHSC COBRE:POLYAMINE METABOLISM IN EBV LYMPHOMAGENESIS

LSUHSC COBRE：EBV 淋巴细胞生成中的多胺代谢

• 批准号: 7720566
• 负责人: RONA S SCOTT
• 金额: $ 32.18万
• 依托单位: LOUISIANA STATE UNIV HSC SHREVEPORT
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-01 至 2009-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7720566
• 关键词: Bioinformatics; Burkitt Lymphoma; Cell Line; Cells; Chromatin; Clone Cells; Computer Retrieval of Information on Scientific Projects Database; DNA; DNA Methyltransferase; DNA Modification Methylases; E-Cadherin; Enzymes; Epigenetic Process; Epstein-Barr Virus Infections; Foundations; Funding; Gene Expression; Gene Silencing; Genes; Genome; Grant; Human; Human Herpesvirus 4; In Vitro; Individual; Infection; Institution; Lymphomagenesis; Maintenance; Malignant - descriptor; Malignant Epithelial Cell; Malignant Neoplasms; Mediating; Membrane Proteins; Messenger RNA; Metabolic Pathway; Metabolism; Methylation; Methyltransferase; MicroRNAs; Modification; Numbers; Oncogenic Viruses; Phenotype; Polyamine Catabolism; Polyamines; Progress Reports; Proteins; Reporting; Research; Research Personnel; Resources; Running; Source; Spermidine/Spermine N1-Acetyltransferase; Testing; Transfection; United States National Institutes of Health; Viral; Virus; cell growth; cellular targeting; imprint; inhibitor/antagonist; malignant phenotype; promoter; tumor

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Project 2-A: Analysis of Polyamine Metabolism in EBV Lymphomagenesis In the Burkitt's lymphoma (BL) cell line Akata, maintenance of the malignant phenotype in vitro is dependent on retention of the EBV genome. Global gene expression analysis of paired EBV-positive and -negative Akata cell clones identified spermidine/spermine N1-acetyltransferase (SSAT) as one of a limited number of genes whose expression was significantly decreased in EBV-positive clones. SSAT is a key enzyme in the catabolism of polyamines, which are essential for cell growth. Increased polyamine levels have been detected in a number of tumors. Thus, we sought to test the hypothesis that decreased SSAT mRNA in EBV-infected cells represents viral manipulation of the polyamine metabolic pathway and a factor in EBV lymphomagenesis. We have concluded the polyamine studies, with final progress reported below. Those studies have provided the foundation for a new direction, outlined in project 2-B. Project 2-B: EBV microRNA-Mediated Epigenetic Modification of Cellular Chromatin Carcinoma cell lines infected by EBV in vitro developed subclones that lost virus but stably retained a morphological phenotypic, induced at infection, which distinguished them from the EBV-negative parental cell line. When transiently infected clones were compared by gene expression arrays to their EBV-negative parental counterparts, some 80 downregulated genes (many of which are hypermethylated in cancer) were identified in cells that had lost virus. Treatment with methyltransferase inhibitors restored the parental cell morphologic phenotype (and, in cases tested, gene expression). These preliminary observations have led us to test the hypothesis that EBV induces stable epigenetic changes that may make virus redundant with respect to continued malignant progression. Retention of a virally-induced epigenetic imprint in transiently infected cells introduces a new paradigm for how a human tumor virus might mechanistically regulate a cell in a "hit-and-run" fashion. We will focus on determining which EBV gene products contribute to epigenetic modification of cellular chromatin. EBV latent membrane protein 1 (LMP1) has been reported to induce DNA methyltransferase 1, 3a, and 3b and hypermethylate the E-cadherin promoter. However, the discovery of at least 17 EBV microRNAs (miRNAs), together with the ability of cellular miRNAs to target DNA for gene silencing, prompted our hypothesis that the EBV miRNAs direct methylation of specific cellular genes in a sequence specific manner. Using bioinformatic approaches, we will query which EBV miRNAs might target these cellular promoters. Transfection of the individual miRNA will provide a direct demonstration that candidate miRNAs so identified do in fact produce epigenetic silencing in EBV infection.

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 项目2-A：EB病毒淋巴肿大的多胺代谢分析 在Burkitt淋巴瘤细胞株Akata中，体外恶性表型的维持依赖于EBV基因组的保留。对EBV阳性和阴性AKATA细胞克隆的全球基因表达分析表明，亚精胺/精胺N1-乙酰转移酶(SSAT)是在EBV阳性克隆中表达显著降低的少数基因之一。SSAT是多胺分解代谢的关键酶，多胺对细胞生长至关重要。在一些肿瘤中检测到多胺水平升高。因此，我们试图验证这一假设，即EBV感染细胞中SSAT mRNA的减少代表病毒对多胺代谢途径的操纵，以及EBV淋巴肿大的一个因素。我们已经完成了对多胺的研究，最后的进展报告如下。这些研究为项目2-B概述的新方向奠定了基础。 项目2-B：EBV-microRNA介导的细胞染色质表观遗传修饰 在体外感染EBV的癌细胞株形成了亚克隆，这些亚克隆丢失了病毒，但稳定地保留了在感染时诱导的形态表型，这使它们有别于EBV阴性的亲本细胞系。当通过基因表达阵列将暂时感染的克隆与EBV阴性的亲代克隆进行比较时，在丢失病毒的细胞中发现了约80个下调基因(其中许多在癌症中高度甲基化)。甲基转移酶抑制剂的治疗恢复了亲代细胞的形态表型(在测试的病例中，还恢复了基因表达)。这些初步观察结果使我们检验了一种假设，即EBV诱导稳定的表观遗传学变化，这可能使病毒在持续的恶性进展中变得多余。在短暂感染的细胞中保留病毒诱导的表观遗传印记，为人类肿瘤病毒如何以一种“打了就跑”的方式机械地调节细胞引入了一个新的范例。我们将专注于确定哪些EBV基因产物有助于细胞染色质的表观遗传修饰。EB病毒潜伏膜蛋白1(LMP1)可诱导DNA甲基转移酶1、3a和3b，并使E-钙粘蛋白启动子高甲基化。然而，至少17个EBV microRNAs(MiRNAs)的发现，加上细胞miRNAs靶向DNA进行基因沉默的能力，促使我们假设EBV miRNAs以序列特异性的方式指导特定细胞基因的甲基化。利用生物信息学方法，我们将查询哪些EBV miRNAs可能针对这些细胞启动子。单个miRNA的转染将提供一个直接的证据，表明这样确定的候选miRNA实际上在EBV感染中产生表观遗传沉默。