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: 8386397
• 负责人: Elizabeth J Perlman
• 金额: $ 20.53万
• 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 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8386397
• 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; 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

DESCRIPTION (provided by applicant): 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 develo 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 fo 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. PUBLIC HEALTH RELEVANCE: This project uses a human tumor, rhabdoid tumor, as a model for investigating the loss of the SMARCB1 gene, a key member of the SWI/SNF chromatin remodeling complex. This has relevance to the mechanisms involved in the very earliest stages of differentiation of embryonic stem cells, and to the development of cancer. Therapeutic intervention may contribute to the treatment of children with rhabdoid tumor as well as a large number of other tumors that show aberrant SWI/SNF function.

描述（由申请人提供）：SMARCB1（HSNF5/INI-1）基因编码INI-1蛋白，Ini-1蛋白是SWI/SNF染色质重塑复合物的成分。虽然已知SWI/SNF综合体在转录调节中起着重要作用，但它在很大程度上是如此 未知。色粒肿瘤（RT）是婴儿期的罕见，高度恶性的肉瘤，表现出SMARCB1的突变和/或缺失。我们最近报道了RT的全球基因表达模式，并提供了证据表明，在关键发育窗口中，RT在非常早期的祖细胞内出现，在此窗口中，SMARCB1的丧失直接导致对细胞周期蛋白依赖激酶抑制的分化和丧失的抑制作用。我们提供了其他证据，表明这些变化在很大程度上是由组蛋白甲基化的变化介导的。在这项提案中，我们检验了我们的假设，即早期祖细胞中SMARCB1的丧失导致全球未能释放Polycomb组对二价基因介导的抑制性H3K27me3，从而导致逮捕的发育和异常增殖。目标1：与三种RT细胞系相比，要在hESC内敲门SMARCB1并测量细胞增殖，分化，基因表达和DNA甲基化的变化。我们将利用RNA干扰在两个hESC中敲除SMARCB1，并测量增殖，EZH2表达，分化以及RNA和DNA甲基化变化的变化。这些将与三种RT细胞系中的这些特征进行比较。在这些研究中，将将全球RNA和DNA甲基化分析与在本提案之外进行的全局芯片seq检测到的RT进行比较。目标2：研究EZH2药物抑制对EZH2对SMARCB1缺陷型细胞在体外和体内的细胞增殖的直接和间接影响。 EZH2代表了人类中最重要的聚癌基团蛋白，并且已被证明在大量肿瘤中被上调。因此，它是一个有吸引力的治疗靶标。我们已经与葛兰素史克建立了一项协议，以研究准备临床前开发的有希望的EZH2抑制剂。我们将进行体外细胞毒性测定 在三个RT细胞系以及对异种移植物的体内研究。在我们进行早期临床试验的能力之前，需要进行的体外和体内研究。相关性：总体生存率为23％，新的治疗选择是 RT迫切需要。如果我们的假设是正确的，则可能导致新的治疗靶标和其他许多显示组蛋白修饰或EZH2过表达的肿瘤。此外，它将引入对早期胚胎分化和肿瘤发展的独特而重要的表观遗传控制模型。长期，这些研究将有助于确定组蛋白修饰与其他表观遗传机制相互作用的潜在机制。然后，这将使在不同的患者人群，发育阶段和疾病中更广泛地对表观遗传调节进行研究。 公共卫生相关性：该项目使用人类肿瘤，横纹肌肿瘤，作为研究SMARCB1基因丧失的模型，SMARCB1基因是SWI/SNF染色质重塑络合物的关键成员。这与胚胎干细胞分化的最早阶段涉及的机制以及与癌症的发展有关。治疗性干预可能有助于治疗横纹肌肿瘤儿童以及显示异常SWI/SNF功能的其他大量肿瘤。