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.

项目总结/摘要 砷和苯并[a]芘（BaP）是最常见的环境污染物之一， 砷和BaP的混合物非常常见。我们对砷和苯并（a）芘协同作用的影响和机理的认识， 暴露是有限的。本研究的目的是确定砷和BaP协同作用的机制。 exposure.表观遗传学是指基因表达模式的可遗传变化，这些变化不是由变化引起的 在DNA序列中，但由DNA甲基化、组蛋白翻译后修饰和非编码介导 RNA。癌症干细胞（CSC）是具有正常干细胞特征的癌细胞。CSC或CSC- Like细胞被认为是癌症起始细胞。虽然砷的毒性作用机制尚不清楚， 认为苯并（a）芘的毒性作用主要取决于其代谢活化和DNA加合物的形成。的 砷对DNA加合物水平的影响存在争议，这表明其他机制可能起作用。 砷和苯并（a）芘共同暴露的联合效应中的关键作用。我们的初步研究发现：（i）砷和BaP 联合暴露在诱导细胞转化、CSC样特性和肺肿瘤方面具有协同效应;（ii）砷 BaP共暴露对BPDE-DNA加合物水平无协同作用。相比之下，共同曝光显示出 通过增加组蛋白H3 K9水平证明的表观遗传失调的协同效应 甲基转移酶SUV 39 H1和H3抑制性甲基化标记H3 K9 me 2。此外，联合曝光还 在降低细胞因子信号传导抑制因子3（SOCS 3）水平和增加Akt （iii）shRNA敲低SUV 39 H1降低H3 K9 me 2水平，增加SOCS 3水平，降低H3 K9 me 2水平。 Akt和Erk 1/2活化和软琼脂集落形成以及CSC样性质;（iv）稳定再表达SOCS 3 降低Akt、Erk 1/2活化、软琼脂集落形成和CSC样性质;（v）抑制Akt和Erk 1/2 减少软琼脂集落形成和CSC样性质;和（vi）砷和BaP共同暴露显著 增加芳烃受体（AhR）的核定位，siRNA敲低AhR大大降低了 在砷和BaP共暴露转化的细胞中的SUV 39 H1水平。根据我们的初步数据， 假设：（i）砷和BaP共同暴露通过协同激活AhR上调HMTase SUV 39 H1; (ii)SUV 39 H1的上调导致SOCS 3的下调;以及（iii）SOCS 3的下调导致SUV 39 H1的上调导致SOCS 3的下调。 更强的Akt和Erk 1/2激活，增强细胞转化和CSC样特性，从而增加肺 肿瘤发生目的1：砷和苯并（a）芘联合暴露显著增强细胞凋亡 通过协同激活AhR上调HMTase SUV 39 H1来抑制转化和肿瘤发生。目的 图2：砷和BaP共同暴露上调SUV 39 H1可增强细胞转化和肿瘤发生 通过下调SOCS 3导致Akt和Erk 1/2的更强激活。目标3：同时灭活 天然化合物Withaferin A对Akt和Erk 1/2的作用削弱了砷和BaP协同作用。 在小鼠中诱导细胞转化和肺肿瘤发生。