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Liu A, Li X, Hao Z, Cao J, Li H, Sun M, Zhang Z, Liang R, Zhang H. Alterations of DNA methylation and mRNA levels of CYP1A1, GSTP1, and GSTM1 in human bronchial epithelial cells induced by benzo[a]pyrene. Toxicol Ind Health 2022; 38:127-138. [PMID: 35193440 DOI: 10.1177/07482337211069233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Benzo[a]pyrene (B[a]P) is a known human carcinogen and plays a major function in the initiation of lung cancer at its first proximity. However, the underlying molecular mechanisms are less well understood. In this study, we investigated the impact of B[a]P treatment on the DNA methylation and mRNA levels of CYP1A1, GSTP1, and GSTM1 in human bronchial epithelial cells (16HBEs), and provide scientific evidence for the mechanism study on the carcinogenesis of B[a]P. We treated 16HBEs with DMSO or concentrations of B[a]P at 1, 2, and 5 mmol/L for 24 h, observed the morphological changes, determined the cell viability, DNA methylation, and mRNA levels of CYP1A1, GSTP1, and GSTM1. Compared to the DMSO controls, B[a]P treatment had significantly increased the neoplastic cell number and cell viability in 16HBEs at all three doses (1, 2, and 5 mmol/L), and had significantly reduced the CYP1A1 and GSTP1 DNA promoter methylation levels. Following B[a]P treatment, the GSTM1 promoter methylation level in 16HBEs was profoundly reduced at low dose group compared to the DMSO controls, yet it was significantly increased at both middle and high dose groups. The mRNA levels of CYP1A1, GSTP1, and GSTM1 were significantly decreased in 16HBEs following B[a]P treatment at all three doses. The findings demonstrate that B[a]P promoted cell proliferation in 16HBEs, which was possibly related to the altered DNA methylations and the inhibited mRNA levels in CYP1A1, GSTP1, and GSTM1.
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Affiliation(s)
- Aixiang Liu
- Department of Environmental Health, School of Public Health, 74648Shanxi Medical University, Taiyuan, Shanxi, China.,Department of Health Information Management, 74648Shanxi Medical University Fenyang College, Fenyang, Shanxi, China
| | - Xin Li
- Center of Disease Control and Prevention, 442190Taiyuan Iron and Steel Co Ltd, Taiyuan, Shanxi, China
| | - Zhongsuo Hao
- Department of Environmental Health, School of Public Health, 74648Shanxi Medical University, Taiyuan, Shanxi, China
| | - Jingjing Cao
- Department of Environmental Health, School of Public Health, 74648Shanxi Medical University, Taiyuan, Shanxi, China
| | - Huan Li
- Department of Environmental Health, School of Public Health, 74648Shanxi Medical University, Taiyuan, Shanxi, China
| | - Min Sun
- Department of Environmental Health, School of Public Health, 74648Shanxi Medical University, Taiyuan, Shanxi, China
| | - Zhihong Zhang
- Department of Environmental Health, School of Public Health, 74648Shanxi Medical University, Taiyuan, Shanxi, China
| | - Ruifeng Liang
- Department of Environmental Health, School of Public Health, 74648Shanxi Medical University, Taiyuan, Shanxi, China
| | - Hongmei Zhang
- Department of Environmental Health, School of Public Health, 74648Shanxi Medical University, Taiyuan, Shanxi, China
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WU JING, WANG YANING, WO DA, ZHANG LIJUAN, LI JUE. Nuclear respiratory factor 1 overexpression attenuates anti-benzopyrene-7,8-diol-9,10-epoxide-induced S-phase arrest of bronchial epithelial cells. Mol Med Rep 2016; 13:4372-8. [DOI: 10.3892/mmr.2016.5065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 01/11/2016] [Indexed: 11/06/2022] Open
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Garige M, Sharma S. Cellular deficiency of Werner syndrome protein or RECQ1 promotes genotoxic potential of hydroquinone and benzo[a]pyrene exposure. Int J Toxicol 2014; 33:373-81. [PMID: 25228686 DOI: 10.1177/1091581814547422] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The 5 known RecQ helicases in humans (RECQ1, BLM, WRN, RECQL4, and RECQ5) have demonstrated roles in diverse genome maintenance mechanisms but their functions in safeguarding the genome from environmental toxicants are poorly understood. Here, we have evaluated a potential role of WRN (mutated in Werner syndrome) and RECQ1 (the most abundant homolog of WRN) in hydroquinone (HQ)- and benzo[a]pyrene (BaP)-induced genotoxicity. Silencing of WRN or RECQ1 expression in HeLa cells increased their sensitivity to HQ and BaP but elicited distinct DNA damage response. The RECQ1-depleted cells exhibited increased replication protein A phosphorylation, Chk1 activation, and DNA double-strand breaks (DSBs) as compared to control or WRN-depleted cells following exposure to BaP treatment. The BaP-induced DSBs in RECQ1-depleted cells were dependent on DNA-dependent protein kinase activity. Notably, loss of WRN in RECQ1-depleted cells ameliorated BaP toxicity. Collectively, our results provide first indication of nonredundant participation of WRN and RECQ1 in protection from the potentially carcinogenic effects of BaP and HQ.
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Affiliation(s)
- Mamatha Garige
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, NW, Washington, DC, USA
| | - Sudha Sharma
- Department of Biochemistry and Molecular Biology, College of Medicine, Howard University, NW, Washington, DC, USA
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Zhao P, Fu J, Yao B, Song Y, Mi L, Li Z, Shang L, Hao W, Zhou Z. In vitro malignant transformation of human bronchial epithelial cells induced by benzo(a)pyrene. Toxicol In Vitro 2012; 26:362-8. [DOI: 10.1016/j.tiv.2011.12.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 12/12/2011] [Accepted: 12/20/2011] [Indexed: 01/01/2023]
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Downregulation of Cdc2/CDK1 kinase activity induces the synthesis of noninfectious human papillomavirus type 31b virions in organotypic tissues exposed to benzo[a]pyrene. J Virol 2010; 84:4630-45. [PMID: 20181698 DOI: 10.1128/jvi.02431-09] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Epidemiological studies suggest that human papillomavirus (HPV)-infected women who smoke face an increased risk for developing cervical cancer. We have previously reported that exposure of HPV-positive organotypic cultures to benzo[a]pyrene (BaP), a major carcinogen in cigarette smoke, resulted in enhanced viral titers. Since BaP is known to deregulate multiple pathways of cellular proliferation, enhanced virion synthesis could result from carcinogen/host cell interaction. Here, we report that BaP-mediated upregulation of virus synthesis is correlated to an altered balance between cell cycle-specific cyclin-dependent kinase (CDK) activity profile compared with controls. Specifically, BaP treatment increased accumulation of hyperphosphorylated retinoblastoma protein (pRb) which coincided with increased cdc2/CDK1 kinase activity, but which further conflicted with the simultaneous upregulation of CDK inhibitors p16(INK4) and p27(KIP1), which normally mediate pRb hypophosphorylation. In contrast, p21(WAF1) and p53 levels remained unchanged. Under these conditions, CDK6 and CDK2 kinase activities were decreased, whereas CDK4 kinase activity remained unchanged. The addition of purvalanol A, a specific inhibitor of CDK1 kinase, to BaP-treated cultures, resulted in the production of noninfectious HPV type 31b (HPV31b) particles. In contrast, infectivity of control virus was unaffected by purvalanol A treatment. BaP targeting of CDK1 occurred independently of HPV status, since BaP treatment also increased CDK1 activity in tissues derived from primary keratinocytes. Our data indicate that HPV31b virions synthesized in the presence of BaP were dependent on BaP-mediated alteration in CDK1 kinase activity for maintaining their infectivity.
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Zhang X, Neganova I, Przyborski S, Yang C, Cooke M, Atkinson SP, Anyfantis G, Fenyk S, Keith WN, Hoare SF, Hughes O, Strachan T, Stojkovic M, Hinds PW, Armstrong L, Lako M. A role for NANOG in G1 to S transition in human embryonic stem cells through direct binding of CDK6 and CDC25A. ACTA ACUST UNITED AC 2009; 184:67-82. [PMID: 19139263 PMCID: PMC2615089 DOI: 10.1083/jcb.200801009] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this study, we show that NANOG, a master transcription factor, regulates S-phase entry in human embryonic stem cells (hESCs) via transcriptional regulation of cell cycle regulatory components. Chromatin immunoprecipitation combined with reporter-based transfection assays show that the C-terminal region of NANOG binds to the regulatory regions of CDK6 and CDC25A genes under normal physiological conditions. Decreased CDK6 and CDC25A expression in hESCs suggest that both CDK6 and CDC25A are involved in S-phase regulation. The effects of NANOG overexpression on S-phase regulation are mitigated by the down-regulation of CDK6 or CDC25A alone. Overexpression of CDK6 or CDC25A alone can rescue the impact of NANOG down-regulation on S-phase entry, suggesting that CDK6 and CDC25A are downstream cell cycle effectors of NANOG during the G1 to S transition.
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Affiliation(s)
- Xin Zhang
- NorthEast England Stem Cell Institute, Institute of Human Genetics, Newcastle University, International Centre for Life, Newcastle upon Tyne, England, UK
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Wang Z, Qi Y, Chen Q, Yang D, Tang S, Jin X, Gao J, Fu J, Zhou Z, Wang J, Xiao X. Cyclin A is essential for the p53-modulated inhibition from benzo(a)pyrene toxicity in A549 cells. Toxicology 2009; 256:1-6. [DOI: 10.1016/j.tox.2008.10.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 10/18/2008] [Accepted: 10/25/2008] [Indexed: 12/23/2022]
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Elliott A, Reiners JJ. Suppression of autophagy enhances the cytotoxicity of the DNA-damaging aromatic amine p-anilinoaniline. Toxicol Appl Pharmacol 2008; 232:169-79. [PMID: 18655802 PMCID: PMC2605791 DOI: 10.1016/j.taap.2008.06.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 06/18/2008] [Accepted: 06/25/2008] [Indexed: 01/15/2023]
Abstract
p-Anilinoaniline (pAA) is an aromatic amine that is widely used in hair dying applications. It is also a metabolite of metanil yellow, an azo dye that is commonly used as a food coloring agent. Concentrations of pAA between 10 and 25 microM were cytostatic to cultures of the normal human mammary epithelia cell line MCF10A. Concentrations >or=50 microM were cytotoxic. Cytostatic concentrations induced transient G(1) and S cell cycle phase arrests; whereas cytotoxic concentrations induced protracted arrests. Cytotoxic concentrations of pAA caused DNA damage, as monitored by the alkaline single-cell gel electrophoresis (Comet) assay, and morphological changes consistent with cells undergoing apoptosis and/or autophagy. Enzymatic and western blot analyses, and binding analyses of fluorescent labeled VAD-FMK, suggested that caspase family members were activated by pAA. Western blot analyses documented the conversion of LC3-I to LC3-II, a post-translational modification involved in the development of the autophagosome. Suppression of autophagosome formation, via knockdown of ATG7 with shRNA, prevented pAA-induced vacuolization, enhanced the activation of pro-caspase-3, and increased susceptibility of ATG7-deficient cells to the cytostatic and cytotoxic activities of markedly lower concentrations of pAA. Cells stably transfected with a nonsense shRNA behaved like parental MCF10A cells. Collectively, these data suggest that MCF10A cultures undergo autophagy as a pro-survival response to concentrations of pAA sufficient to induce DNA damage.
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Affiliation(s)
- Althea Elliott
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48201, USA
| | - John J. Reiners
- Institute of Environmental Health Sciences, Wayne State University, Detroit, MI 48201, USA
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Yao B, Fu J, Hu E, Qi Y, Zhou Z. The effects of over-expression and suppression of Cdc25A on the S-phase checkpoint induced by benzo(a)pyrene. Toxicology 2008; 246:180-7. [DOI: 10.1016/j.tox.2008.01.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2007] [Revised: 01/08/2008] [Accepted: 01/08/2008] [Indexed: 12/28/2022]
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