Epigenetic and clinical impact of SMARCB1 loss in cancer

SMARCB1 缺失对癌症的表观遗传学和临床影响

• 批准号: 8495294
• 负责人: Elizabeth J Perlman
• 金额: $ 15.19万
• 依托单位: LURIE CHILDREN'S HOSPITAL OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8495294
• 关键词: 22q11; Address; Agreement; Attention; Biological Assay; Cell Line; Cell Proliferation; Cells; ChIP-seq; Child; Children' s Oncology Group; Chromatin Remodeling Factor; Chromosomes; Clinical; Clinical Research; Clinical Trials; Complex; Cyclin-Dependent Kinases; DNA Methylation; Development; Disease; EZH2 gene; Embryo; Employee Strikes; Epigenetic Process; Excision; Failure; Future; Gene Expression; Gene Expression Profile; Gene Expression Profiling; Genes; Genetic Transcription; Histones; Human; In Vitro; Investigation; Lead; Longitudinal Studies; Malignant - descriptor; Malignant Neoplasms; Measures; Mediating; Methylation; Modeling; Modification; Mutation; Pharmacologic Substance; Play; Polycomb; Proteins; RNA Interference; RNA methylation; Regulation; Reporting; Repression; Rhabdoid Tumor; Role; SMARCB1 gene; Staging; Stem cells; Survival Rate; Testing; Therapeutic Intervention; Transcriptional Regulation; Tumor Cell Line; Xenograft procedure; cytotoxic; embryonic stem cell; histone modification; human embryonic stem cell; in vivo; infancy; inhibitor/antagonist; integrase interactor 1; knock-down; member; new therapeutic target; novel therapeutics; overexpression; patient population; pre-clinical; sarcoma; therapeutic target; tumor

The SMARCB1 (hSNF5/INI-1) gene encodes the INI-1 protein, a component of the SWI/SNF chromatin remodeling complex. While the SWI/SNF complex is known to play an important role in transcriptional regulation, how it does so is largely unknown. Rhabdoid Tumors (RT) are rare, highly malignant sarcomas of infancy that demonstrate mutation and/or deletion of SMARCB1. We recently reported the global gene expression pattern of RT, and provided evidence that RTs arise within very early progenitor cells during a critical developmental window during which loss of SMARCB1 directly results in striking repression of differentiation and loss of cyclin dependent kinase inhibition. We provide additional evidence that these changes are largely mediated by changes in histone methylation. In this proposal we test our hypothesis that loss of SMARCB1 in early progenitor cells results in a global failure to release the polycomb group mediated repressive H3K27me3 on bivalent genes, resulting in arrested development and abnormal proliferation. Aim 1: To knock-down SMARCB1 within hESC and to measure changes in cell proliferation, differentiation, gene expression and DNA methylation compared with three RT cell lines. We will utilize RNA interference to knock-down SMARCB1 in two hESC and measure changes in proliferation, EZH2 expression, differentiation, and RNA and DNA methylation changes. These will be compared to those features in three RT cell lines. Global RNA and DNA methylation analysis in these studies will be compared with histone modifications in RT detected by global ChIP-SEQ being performed outside of this proposal. Aim 2: To investigate the direct and indirect impact of pharmacologic inhibition of EZH2 on cell proliferation in SMARCB1-deficient cells in vitro and in vivo. EZH2 represents the most important polycomb group protein in humans, and has been shown to be upregulated in a large number of tumors. It is therefore an attractive therapeutic target. We have established an agreement with GlaxoSmithKline for the study of a promising EZH2 inhibitor that is ready for preclinical development. We will perform in vitro cytotoxic assays on the three RT cell lines, and in vivo studies on xenografts created from the same cell lines. Both the in vitro and in vivo studies that are proposed are required prior to our ability to develop early clinical trials. Relevance: With an overall survival rate of 23%, new therapeutic options are urgently needed for RT. If our hypothesis is correct, it may result in novel therapeutic targets for RTs and the many other tumors that show histone modification or EZH2 overexpression. In addition, it will introduce a unique and important model of epigenetic control of both early embryonic differentiation and tumor development. Long-term, these studies will help to identify the underlying mechanisms by which histone modifications interact with other epigenetic mechanisms. This would then enable the investigation of epigenetic regulation more broadly in different patient populations, developmental stages, and diseases.

SMARCB 1（hSNF5/INI-1）基因编码INI-1蛋白，其是SWI/SNF染色质的组分 重塑情结虽然已知SWI/SNF复合物在转录调控中起重要作用， 监管，它如何做到这一点在很大程度上是未知的。横纹肌样瘤（RT）是一种罕见的高度恶性肉瘤， 婴儿期表现出SMARCB1突变和/或缺失。我们最近报道了全球基因 RT的表达模式，并提供了证据表明，RT发生在非常早期的祖细胞中， 关键的发育窗口期，在此期间SMARCB 1的缺失直接导致对 分化和细胞周期蛋白依赖性激酶抑制的丧失。我们提供了额外的证据表明，这些 变化主要是由组蛋白甲基化的变化介导的。在这个提议中，我们检验了我们的假设， 早期祖细胞中SMARCB 1的缺失导致polycomb组介导的释放全面失败 抑制H3K27me3双价基因，导致发育停滞和异常增殖。 目的1：敲低hESC内的SMARCB 1并测量细胞增殖的变化， 分化、基因表达和DNA甲基化。我们将利用 RNA干扰在两种hESC中敲低SMARCB 1并测量增殖、EZH2的变化 表达、分化以及RNA和DNA甲基化变化。这些将与那些功能进行比较 在三个RT细胞系中。这些研究中的总体RNA和DNA甲基化分析将与组蛋白 在本提案之外，通过全局ChIP-SEQ检测RT中的修饰。 目的2：探讨EZH2的药理学抑制作用对细胞的直接和间接影响 在体外和体内SMARCB 1缺陷细胞中的增殖。EZH2代表了最重要的 多梳组蛋白在人类中表达，并且已显示在大量肿瘤中上调。是 因此是有吸引力的治疗靶点。我们已经与葛兰素史克达成协议， 研究一种有前途的EZH2抑制剂，已准备好进行临床前开发。我们将进行体外细胞毒性试验 对三种RT细胞系的测定，以及对由相同细胞系产生的异种移植物的体内研究。两者 在我们有能力开展早期临床试验之前，需要进行拟议的体外和体内研究。 相关性：总生存率为23%，RT迫切需要新的治疗选择。 假设是正确的，它可能会导致新的治疗靶点的RT和许多其他肿瘤，显示 组蛋白修饰或EZH2过表达。此外，它还将介绍一种独特而重要的模式， 表观遗传控制早期胚胎分化和肿瘤发育。从长远来看，这些研究将 有助于确定组蛋白修饰与其他表观遗传相互作用的潜在机制 机制等这将使表观遗传调控的调查更广泛地在不同的 患者群体、发育阶段和疾病。