Mechanisms of De Novo Methylation in Cancer

癌症中从头甲基化的机制

• 批准号: 8060542
• 负责人: PETER A JONES
• 金额: $ 44.13万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-17 至 2014-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8060542
• 关键词: Aberrant DNA Methylation; Achievement; Address; Azacitidine; Biochemical; Cells; Chromatin; Colon Carcinoma; Complex; CpG Islands; Custom; Cytosine; DNA; DNA Methylation; DNA Methyltransferase; DNA Modification Methylases; Deamination; Deoxycytidine; Development; Drug Delivery Systems; Drug Design; Enzymes; Epigenetic Process; FDA approved; Funding; Gene Silencing; Genes; Goals; Grant; HCT116 Cells; Health; Histone Deacetylase Inhibitor; Histone H3; Histones; Human; Human Development; Hydrolysis; Inherited; Maintenance; Malignant Neoplasms; Malignant neoplasm of prostate; Maps; Methylation; Methyltransferase; Myelogenous; Normal Cell; Nucleosomes; Patients; Pattern; Pharmaceutical Preparations; Play; Polycomb; Positioning Attribute; Process; Relative (related person); Research; Role; Somatic Cell; Syndrome; Testing; Transcription Initiation Site; Tumor Suppressor Genes; Universities; cancer cell; cancer therapy; cell transformation; chromatin protein; density; design; epigenomics; follow-up; histone modification; inhibitor/antagonist; knock-down; malignant phenotype; prevent; research study; restoration

DESCRIPTION (provided by applicant): The objectives of this grant, which has been funded for almost 30 years, have been to understand the mechanisms for the establishment and inheritance of DNA methylation patterns and to develop drugs which can interfere with cytosine methylation and reactivate silenced genes. This research has led to the recent approval by the FDA of two DNA demethylating agents (5-aza-CR and 5-aza-CdR) for the treatment of myeloid dysplastic syndrome. In the next five year period of the project, we hope to take advantage of epigenomic analysis to understand how DNA methylation patterns are established and maintained by an interaction between DNA methyltransferases and specific chromatin components. To do this, we have developed a custom NimbleGen array allowing for the analyses of nucleosomes, histone modifications and DNA methylation in an integrated way at 1,800 transcription start sites (TSS) in normal and transformed cells. In Specific Aim 1, we will utilize the tiling array to map nucleosomes in both normal (PrECs) and transformed prostate cancer cells (PC3). We shall then determine how interfering with DNA methylation pharmacologically in PC3 cells or genetically in HCT116 colon cancer cells alters the distribution of histone marks focusing on the histone H3-K27me3 mark applied by the polycomb repressive complex 2 (PRC2). In Specific Aim 2, we shall determine how the epigenome is reorganized during the restoration of DNA methylation to HCT116 derivatives (DKO) in which two of the three DNA methyltransferases (DNMT1 and DNMT3B) have been genetically knocked down. In Specific Aim 3, we will follow-up on our new results which show the strong anchoring of the de novo methyltransferases DNMT3A and 3B to nucleosomes. We wish to determine how the enzymes interact with nucleosomes so that we can understand how specific patterns are established. In Specific Aim 4, we will continue our quest to develop DNA demethylating drugs which are more stable than those currently approved by the FDA for cancer treatment and which are able to reverse aberrant DNA methylation, histone modifications and nucleosome positioning. Achievement of these aims should have major impact in our understanding of the epigenetics of cancer and have direct relevance to new strategies to treat and prevent cancer. PUBLIC HEALTH RELEVANCE: It has become clear over the last few years that the abnormal silencing of genes by somatically heritable epigenetic processes, can contribute directly to the formation of human cancers. Although we know that altered patterns of DNA methylation play a fundamental role in the silencing of tumor suppressor genes, we do not know how these altered patterns are set up or how normal patterns are established and inherited during human development. Recent excitement in the field has focused on the potential role of gene silencing mechanisms involving the polycomb repressive complexes (PRCs), which are essential for normal development and have recently been found also to play a role in inactivating tumor suppressor genes. These PRCs can directly silence genes by themselves and also somehow set up genes for more permanent silencing induced by DNA methylation. Recently, the FDA has approved two DNA demethylating agents and one histone deacetylase inhibitor for the treatment of particular kinds of cancer.

描述（由申请人提供）：已有近30年资金的这笔赠款的目标是了解DNA甲基化模式的建立和遗传的机制，并开发出可以干扰胞嘧啶甲基化并重新激活沉默基因的药物。这项研究导致FDA最近获得了两种DNA脱甲基剂（5-Aza-CR和5-Aza-CDR）治疗髓样异常综合征。在该项目的接下来的五年中，我们希望利用表观基因组分析来了解如何通过DNA甲基转移酶与特定染色质成分之间的相互作用来建立和维持DNA甲基化模式。为此，我们开发了一个自定义的敏捷阵列，允许在正常和转化细胞中以1,800转录起始位点（TSS）在1,800转录起始位点（TSS）进行核小体，组蛋白修饰和DNA甲基化的分析。在特定的目标1中，我们将使用平铺阵列来绘制正常（PREC）和转化的前列腺癌细胞（PC3）中的核小体。然后，我们将确定如何在PC3细胞中干扰DNA甲基化药理学或HCT116结肠癌细胞中的遗传学改变了由Polycomb Repressive Complese 2（PRC2）应用于组蛋白H3-K27me3的组蛋白标记的分布（PRC2）。在特定的目标2中，我们将确定在将DNA甲基化恢复到HCT116衍生物（DKO）期间如何重新组织的表观基因组，其中三个DNA甲基转移酶（DNMT1和DNMT3B）中的两个已被遗传击倒。在特定的目标3中，我们将跟进我们的新结果，这些结果表明从头甲基转移酶DNMT3A和3B对核小体的强锚定。我们希望确定酶如何与核小体相互作用，以便我们可以理解如何建立特定模式。在特定目标4中，我们将继续寻求开发DNA脱甲基化药物，这些药物比FDA目前批准的癌症治疗更稳定，这些药物能够逆转异常的DNA甲基化，组蛋白修饰和核小体定位。这些目标的实现应该对我们对癌症表观遗传学的理解产生重大影响，并与治疗和预防癌症的新策略有直接相关。公共卫生相关性：在过去的几年中，人们已经很清楚地表明，通过体形遗传的表观遗传过程对基因的异常沉默可以直接有助于人类癌的形成。尽管我们知道，DNA甲基化的改变模式在肿瘤抑制基因的沉默中起着基本作用，但我们不知道如何建立这些改变的模式或在人类发育过程中如何建立和遗传正常模式。该领域的最新兴奋集中在涉及多肉液抑制复合物（PRC）的基因沉默机制的潜在作用上，这对于正常发育至关重要，最近也发现在灭活肿瘤抑制基因中也起着作用。这些PRC可以自己直接沉默基因，并以某种方式建立基因，以使DNA甲基化引起的更永久的沉默。最近，FDA批准了两种DNA脱甲基剂和一种组蛋白脱乙酰基酶抑制剂，用于治疗特定种类的癌症。