Mechanism of hexavalent chromium carcinogenesis - Role of long non-coding RNA dysregulation

六价铬致癌机制——长链非编码RNA失调的作用

• 批准号: 9813295
• 负责人: Chengfeng Yang
• 金额: $ 34.43万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9813295
• 关键词: 3' Untranslated Regions; Affect; Affinity Chromatography; Biological Assay; Cancer Etiology; Carcinogens; Cell Maintenance; Cells; Chromatin Remodeling Factor; Chronic; Country; DNA Methylation; DNA Repair Gene; Data; Down-Regulation; Environmental Carcinogens; Environmental Health; Epigenetic Process; Exposure to; Gene Expression; Genetic Transcription; Goals; Guanine Nucleotide Exchange Factors; Histones; KDM5B gene; Knockout Mice; Length; Luciferases; Lung; Lysine; MAP Kinase Gene; Malignant Neoplasms; Mediating; Metabolic; Metal Carcinogenesis; Mus; Neoplasm Metastasis; Nuclear; Occupational; Oncogenic; Phenotype; Play; Poly(ADP-ribose) Polymerases; Porifera; Post-Translational Protein Processing; Property; Proteins; RNA; RNA Polymerase II; Reactive Oxygen Species; Regulator Genes; Relapse; Reporter; Review Literature; Role; Series; United States; Untranslated RNA; base; cancer cell; cancer initiation; cancer stem cell; carcinogenesis; carcinogenicity; cell transformation; chromium hexavalent ion; genotoxicity; insight; knock-down; lung carcinogenesis; lung tumorigenesis; novel; overexpression; pollutant; promoter; recruit; rho GTP-Binding Proteins; stem cell differentiation; stem-like cell; therapy resistant; tumorigenesis

PROJECT SUMMARY/ABSTRACT Hexavalent chromium [Cr(VI)] is a common and well-recognized environmental carcinogen causing lung and other cancers, however, the mechanism of Cr(VI) carcinogenesis remains elusive. Previous Cr(VI) carcinogenesis studies mostly focus on its genotoxic effects. However, studies showed that Cr(VI) exposure also causes non- genotoxic effects such as epigenetic changes as evidenced by dysregulations in DNA methylation and histone posttranslational modifications. While these observations open new directions for studying Cr(VI) carcinogenesis, it remains to be determined how Cr(VI)-caused epigenetic dysregulations contribute to Cr(VI) carcinogenesis. Moreover, very little is known about the role of non-coding RNAs (ncRNAs) especially the long non-coding RNAs (lncRNAs), another epigenetic mechanism regulating gene expression, in Cr(VI) carcinogenesis. Recent studies show that lncRNAs are emerging key regulators of gene expression and play critical roles in cancer. The goal of this study is to investigate the mechanism of Cr(VI) carcinogenesis focusing on the role of lncRNA dysregulation. Our preliminary studies found: (i) Chronic Cr(VI) exposure increases the expression of the lncRNA ABHD11-AS1, which contributes causally to Cr(VI)-induced cell transformation, cancer stem cell (CSC)-like property and tumorigenesis; (ii) Chronic Cr(VI) exposure down-regulates the expression of miR-182-5p; but knockdown of ABHD11-AS1 increases the level of miR-182-5p. Moreover, overexpressing miR-182-5p in Cr(VI)-transformed cells significantly reduces their transformed phenotypes, phenocopying the effect of ABHD11-AS1 knockdown; (iii) The Rho GTPase Rac1 and Erk1/2 MAPK are highly activated in Cr(VI)-transformed cells; (iv) The expression level of the oncogenic Rac-GEF Tiam1 is significantly up-regulated in Cr(VI)-transformed cells; but overexpressing miR- 182-5p or knockdown of ABHD11-AS1 greatly decrease Tiam1 level; (v) The expression level of PARP-1, a critical DNA repair gene and a key regulator of gene expression, is significantly up-regulated in Cr(VI)-transformed cells; (vi) The level of protein PARylation is drastically increased in Cr(VI)-transformed cells; inhibition of PARP-1 or knockdown of PARP-1 greatly decrease the levels of protein PARylation and ABHD11-AS1 and the transformed phenotype of Cr(VI)-transformed cells. Based on literature review and our novel preliminary data, our central hypothesis is: “Chronic Cr(VI) exposure-upregulated lncRNA ABHD11-AS1 sponges miR-182-5p and causes its down-regulation, which leads to increased level of the oncogenic Rac-GEF Tiam1 promoting Cr(VI) carcinogenesis”. Three aims are proposed: Aim 1 will determine the mechanism by which chronic Cr(VI) exposure up-regulates ABHD11-AS1. Aim 2 will demonstrate that ABHD11-AS1 sponges miR-182-5p causing its down- regulation and promoting Cr(VI)-exposure-induced CSC-like property, cell transformation and tumorigenesis. And Aim 3 will demonstrate that down-regulation of miR-182-5p increases levels of the oncogenic Rac-GEF Tiam1 promoting Cr(VI)-exposure-induced CSC-like property, cell transformation and tumorigenesis. Tiam1 knockout mice will be used to demonstrate that Tiam1 plays an important role in Cr(VI)-induced lung carcinogenesis.

项目概要/摘要 六价铬 [Cr(VI)] 是一种常见且公认的环境致癌物，可导致肺部和其他疾病 然而，Cr(VI) 致癌的机制仍然难以捉摸。 研究主要集中在其遗传毒性作用上，然而，研究表明，Cr(VI) 暴露也会导致非毒性作用。 遗传毒性效应，例如 DNA 甲基化和组蛋白失调所证明的表观遗传变化 虽然这些观察结果为研究 Cr(VI) 致癌作用开辟了新的方向，但 Cr(VI) 引起的表观遗传失调如何导致 Cr(VI) 致癌仍有待确定。 此外，人们对非编码 RNA (ncRNA) 尤其是长非编码 RNA 的作用知之甚少。 （lncRNA）是 Cr(VI) 致癌作用中另一种调节基因表达的表观遗传机制。 研究表明，lncRNA 是基因表达的新兴关键调节因子，在癌症中发挥着关键作用。 本研究旨在探讨 Cr(VI) 致癌机制，重点关注 lncRNA 失调的作用。 我们的初步研究发现：(i) 慢性 Cr(VI) 暴露会增加 lncRNA ABHD11-AS1 的表达， 它有助于 Cr(VI) 诱导的细胞转化、癌症干细胞 (CSC) 样特性和 肿瘤发生；(ii) 慢性 Cr(VI) 暴露下调 miR-182-5p 的表达； ABHD11-AS1 增加 miR-182-5p 的水平，此外，在 Cr(VI) 转化细胞中过表达 miR-182-5p。 (三) Cr(VI) 转化细胞中 Rho GTPase Rac1 和 Erk1/2 MAPK 高度激活； 致癌 Rac-GEF Tiam1 在 Cr(VI) 转化细胞中显着上调，但过度表达 miR- 182-5p 或 ABHD11-AS1 敲除大大降低 Tiam1 水平； (v) 关键的 PARP-1 表达水平； DNA 修复基因和基因表达的关键调节因子在 Cr(VI) 转化细胞中显着上调； (vi) Cr(VI) 转化细胞中蛋白质 PARylation 的水平显着增加；或抑制 PARP-1； PARP-1 的敲低大大降低了蛋白质 PARylation 和 ABHD11-AS1 的水平，并且转化的 Cr(VI) 转化细胞的表型基于文献综述和我们的新初步数据，我们的中心。 假设是：“慢性 Cr(VI) 暴露上调的 lncRNA ABHD11-AS1 海绵 miR-182-5p 并导致其 下调，导致致癌 Rac-GEF Tiam1 促进 Cr(VI) 水平升高 提出了三个目标： 目标 1 将确定慢性 Cr(VI) 暴露的机制 上调 ABHD11-AS1 将证明 ABHD11-AS1 海绵 miR-182-5p 导致其下调。 调节和促进 Cr(VI) 暴露诱导的 CSC 样特性、细胞转化和肿瘤发生。 目标 3 将证明 miR-182-5p 的下调会增加致癌 Rac-GEF Tiam1 的水平 促进 Cr(VI) 暴露诱导的 CSC 样特性、细胞转化和 Tiam1 敲除。 将使用小鼠来证明 Tiam1 在 Cr(VI) 诱导的肺癌发生中发挥重要作用。