Epigenetic mechanism of the synergistic tumorigenic effect of arsenic and benzo[a]pyrene co-exposure

砷与苯并[a]芘共暴露协同致瘤作用的表观遗传机制

• 批准号: 9762924
• 负责人: Zhishan Wang
• 金额: $ 34.43万
• 依托单位: UNIVERSITY OF KENTUCKY
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2023-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9762924
• 关键词: A/J Mouse; Agar; Arsenic; Aryl Hydrocarbon Receptor; Benzo(a)pyrene; CISH gene; CRISPR/Cas technology; Carcinogens; Cells; Characteristics; DNA; DNA Adduction; DNA Adducts; DNA Methylation; DNA Sequence; Data; Down-Regulation; Environmental Health; Environmental Pollutants; Epigenetic Process; Epithelial Cells; Exposure to; Gene Expression Profile; General Population; Goals; Heritability; Histone H3; Histones; Human; Impairment; Knock-out; Knowledge; Literature; Lung Neoplasms; Malignant - descriptor; Malignant Neoplasms; Malignant neoplasm of lung; Meat; Mediating; Metabolic Activation; Methylation; Methyltransferase; Molecular Target; Mus; Nuclear Receptors; Nucleotide Excision Repair; Oral Administration; Pharmacology; Play; Post-Translational Protein Processing; Prevention strategy; Property; Reporting; Risk; Role; Small Interfering RNA; Source; Stem cells; Suspensions; Toxic effect; Untranslated RNA; Up-Regulation; arsenic carcinogenesis; base; cancer cell; cancer risk; cancer stem cell; carcinogenesis; carcinogenicity; cell transformation; cigarette smoke; contaminated drinking water; cooking; cytotoxic; disorder prevention; exposed human population; inhibitor/antagonist; insight; knock-down; lung tumorigenesis; novel; overexpression; protective effect; small hairpin RNA; stem-like cell; tumorigenesis; tumorigenic

PROJECT SUMMARY/ABSTRACT Arsenic and benzo[a]pyrene (BaP) are among the most common environmental pollutants and human exposure to arsenic and BaP mixture is very common. Our knowledge on the effect and mechanism of arsenic and BaP co- exposure is limited. The goal of this study is to determine the mechanism of the effect of arsenic and BaP co- exposure. Epigenetics refers to heritable changes in the pattern of gene expression that are not caused by changes in DNA sequence, but are mediated by DNA methylation, histone posttranslational modifications and noncoding RNAs. Cancer stem cells (CSCs) are cancer cells possessing characteristics of normal stem cells. CSCs or CSC- like cells are considered as cancer initiating cells. While the mechanism of arsenic toxic effect is not clearly defined, it is thought that the toxic effect of BaP mainly depends on its metabolic activation and DNA adduct formation. The reported effects of arsenic on DNA adduct level are controversial, suggesting that other mechanisms may play a key role in the combined effect of arsenic and BaP co-exposure. Our preliminary studies found: (i) Arsenic and BaP co-exposure has a synergistic effect in inducing cell transformation, CSC-like property and lung tumors; (ii) Arsenic and BaP co-exposure has no synergistic effect on BPDE-DNA adduct level. In contrast, the co-exposure shows a synergistic effect in epigenetic deregulations as evidenced by increasing the levels of histone H3K9 methyltransferase SUV39H1 and H3 repressive methylation mark H3K9me2. Moreover, the co-exposure also shows a synergistic effect in reducing the level of suppressor of cytokine signaling 3 (SOCS3) and increasing Akt and Erk1/2 activation; (iii) ShRNA knockdown SUV39H1 reduces H3K9me2 level, increases SOCS3 level, reduces Akt and Erk1/2 activation and soft agar colony formation and CSC-like property; (iv) Stably re-expressing SOCS3 reduces Akt, Erk1/2 activation, soft agar colony formation and CSC-like property; (v) Inhibiting Akt and Erk/1/2 reduces soft agar colony formation and CSC-like property; and (vi) Arsenic and BaP co-exposure significantly increases aryl hydrocarbon receptor (AhR) nuclear localization and siRNA knockdown AhR greatly reduces the level of SUV39H1 in arsenic and BaP co-exposure-transformed cells. Based on our preliminary data, our central hypothesis is: (i) Arsenic and BaP co-exposure up-regulates HMTase SUV39H1 via synergistically activating AhR; (ii) Up-regulation of SUV39H1 leads to SOCS3 down-regulation; and (iii) Down-regulation of SOCS3 causes a stronger Akt and Erk1/2 activation, which enhances cell transformation and CSC-like property thus increasing lung tumorigenesis. Three aims are proposed: Aim 1: Arsenic and BaP co-exposure significantly enhances cell transformation and tumorigenesis by up-regulating HMTase SUV39H1 via synergistically activating AhR. Aim 2: SUV39H1 up-regulation by arsenic and BaP co-exposure enhances cell transformation and tumorigenesis by down-regulating SOCS3 leading to stronger activation of Akt and Erk1/2. Aim 3: Simultaneously inactivating both Akt and Erk1/2 by a natural compound Withaferin A impairs the synergistic effect of arsenic and BaP co- exposure in inducing cell transformation and lung tumorigenesis in mice.

项目摘要/摘要 砷和苯并[a] pyrene（BAP）是最常见的环境污染物之一，人类暴露于 砷和BAP混合物非常普遍。我们对砷和BAP共同的影响和机制的了解 暴露是有限的。这项研究的目的是确定砷和BAP共同作用的机理 接触。表观遗传学是指基因表达模式的可遗传变化，而不是由变化引起的 在DNA序列中，但是由DNA甲基化，翻译后修饰和非编码介导的 RNA。癌症干细胞（CSC）是具有正常干细胞特征的癌细胞。 CSC或CSC- 像细胞一样被认为是癌症引发细胞。虽然砷毒性作用的机制尚未明确定义，但 据认为，BAP的毒性作用主要取决于其代谢激活和DNA加合物的形成。这 报道的砷对DNA加合物水平的影响是有争议的，这表明其他机制可能会发挥作用 在砷和BAP共曝光的综合作用中的关键作用。我们的初步研究发现：（i）砷和bap 共曝光对诱导细胞转化，CSC样性质和肺部肿瘤具有协同作用。 （ii）砷 BAP共曝光对BPDE-DNA加合物水平没有协同作用。相反，共曝光显示 在表观遗传消失中的协同作用，可以通过增加组蛋白H3K9的水平来证明 甲基转移酶SUV39H1和H3抑制甲基化标记H3K9me2。此外，共同暴露 在降低细胞因子信号传导3（SOCS3）的抑制水平并增加Akt方面显示出协同作用 和ERK1/2激活； （iii）shRNA敲低SUV39H1降低H3K9me2水平，增加SOCS3水平，降低 AKT和ERK1/2激活以及软琼脂菌落形成和类似CSC的特性； （iv）稳定重新表达SOCS3 降低AKT，ERK1/2激活，软琼脂菌落形成和类似CSC的特性； （v）抑制AKT和ERK/1/2 减少软琼脂菌落形成和类似CSC的特性； （VI）砷和BAP共同暴露 增加芳基烃受体（AHR）核定位，siRNA敲低AHR大大降低了 砷和BAP共曝光转化细胞中的Suv39H1水平。根据我们的初步数据，我们的中心 假设是：（i）砷和BAP共曝光通过协同激活AHR上调HMTase SUV39H1； （ii）SUV39H1的上调导致SOCS3下调； （iii）SOCS3的下调导致A 更强的Akt和ERK1/2激活，从而增强细胞转化和类似CSC的特性，从而增加了肺 肿瘤发生。提出了三个目的：目标1：砷和BAP共同暴露会显着增强细胞 通过协同激活AHR上调HMTase SUV39H1的转化和肿瘤发生。目的 2：SUV39H1通过砷和BAP共同暴露在上调可增强细胞转化和肿瘤发生 通过下调SOCS3，导致AKT和ERK1/2的激活更强。目标3：同时灭活 通过天然化合​​物和脂蛋白A都会损害砷和BAP共同的协同作用 在诱导小鼠中诱导细胞转化和肺肿瘤发生的暴露中。