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

基本信息

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
项目类别：
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

项目摘要

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.

项目概要/摘要砷和苯并[a]芘 (BaP) 是最常见的环境污染物，也是人类接触的最常见的污染物砷和BaP的混合物很常见。我们对砷和 BaP 共混物的作用和机制的了解曝光度有限。本研究的目的是确定砷和 BaP 共混物的作用机制。接触。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存在于 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- 类似的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，人们认为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 加合物水平的影响存在争议，这表明其他机制可能发挥了作用砷和 BaP 共同暴露的联合效应中起关键作用。我们的初步研究发现： (i) 砷和 BaP 共暴露在诱导细胞转化、CSC样特性和肺部肿瘤方面具有协同作用； (二) 砷 BaP共暴露对BPDE-DNA加合物水平没有协同作用。相比之下，共同曝光显示通过增加组蛋白 H3K9 水平证明表观遗传失调的协同效应甲基转移酶 SUV39H1 和 H3 抑制性甲基化标记 H3K9me2。此外，此次联名曝光还在降低细胞因子信号传导抑制因子 3 (SOCS3) 水平和增加 Akt 方面显示出协同效应和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 激活以及软琼脂集落形成和 CSC 样特性； (iv) 稳定地重新表达 SOCS3 降低 Akt、Erk1/2 激活、软琼脂集落形成和 CSC 样特性； (v) 抑制 Akt 和 Erk/1/2 减少软琼脂集落形成和 CSC 样特性； (vi) 砷和 BaP 共同暴露显着增加芳烃受体 (AhR) 核定位，并且 siRNA 敲低 AhR 大大降低砷和 BaP 共暴露转化细胞中 SUV39H1 的水平。根据我们的初步数据，我们的中央假设是：（i）砷和 BaP 共同暴露通过协同激活 AhR 上调 HMTase SUV39H1； (ii) SUV39H1的上调导致SOCS3下调； (iii) SOCS3 的下调导致更强的 Akt 和 Erk1/2 激活，增强细胞转化和 CSC 样特性，从而增加肺功能肿瘤发生。提出了三个目标：目标 1：砷和 BaP 共同暴露显着增强细胞通过协同激活 AhR 上调 HMTase SUV39H1 来实现转化和肿瘤发生。目的图2：砷和BaP共同暴露上调SUV39H1增强细胞转化和肿瘤发生通过下调 SOCS3 导致 Akt 和 Erk1/2 更强的激活。目标 3：同时灭活天然化合物 Withaferin A 的 Akt 和 Erk1/2 都会削弱砷和 BaP 的协同作用暴露诱导小鼠细胞转化和肺肿瘤发生。