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Guo X, Xu H, Seo JE. Application of HepaRG cells for genotoxicity assessment: a review. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, TOXICOLOGY AND CARCINOGENESIS 2024; 42:214-237. [PMID: 38566478 DOI: 10.1080/26896583.2024.2331956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
There has been growing interest in the use of human-derived metabolically competent cells for genotoxicity testing. The HepaRG cell line is considered one of the most promising cell models because it is TP53-proficient and retains many characteristics of primary human hepatocytes. In recent years, HepaRG cells, cultured in both a traditional two-dimensional (2D) format and as more advanced in-vivo-like 3D spheroids, have been employed in assays that measure different types of genetic toxicity endpoints, including DNA damage, mutations, and chromosomal damage. This review summarizes published studies that have used HepaRG cells for genotoxicity assessment, including cell model evaluation studies and risk assessment for various compounds. Both 2D and 3D HepaRG models can be adapted to several high-throughput genotoxicity assays, generating a large number of data points that facilitate quantitative benchmark concentration modeling. With further validation, HepaRG cells could serve as a unique, human-based new alternative methodology for in vitro genotoxicity testing.
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Affiliation(s)
- Xiaoqing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
| | - Hannah Xu
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
| | - Ji-Eun Seo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
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Sato A, Ishigami A. Effects of heated tobacco product aerosol extracts on DNA methylation and gene transcription in lung epithelial cells. Toxicol Appl Pharmacol 2023; 475:116637. [PMID: 37499768 DOI: 10.1016/j.taap.2023.116637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 07/18/2023] [Accepted: 07/24/2023] [Indexed: 07/29/2023]
Abstract
AIMS Smoking causes DNA methylation (DNAm) alterations that lead to lung cancer development. Although the use of heated tobacco products (HTPs) has recently increased, their impact on health remains unclear. This study aimed to evaluate the effects of HTPs on DNAm and gene transcription in human lung epithelial cells in vitro. MAIN METHODS Human lung adenocarcinoma (A549) cells with type II alveolar epithelial characteristics were treated with aerosol extracts of two HTPs or a smoke extract of combustible reference cigarette (RC). Global 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) levels were quantified using dot blot analysis. Furthermore, reduced representation of bisulfite sequencing, DNA microarray, and quantitative PCR analyses were performed to determine CpG methylation and gene transcription changes induced by HTP and RC. KEY FINDINGS Global 5-mC and 5-hmC levels were decreased by the RC extract but not the HTP extracts. However, an HTP extract altered the CpG methylation pattern, and Gene Ontology enrichment analysis of the differentially methylated regions of the RC and HTP groups showed a similar pattern. The HTP extract affected gene expression, albeit to a lesser extent than the RC extract. In particular, the HTP extract markedly affected the mRNA expression and promoter methylation of cytochrome P450 family 1 subfamily A member 1 (CYP1A1), which is associated with carcinogenic risk. SIGNIFICANCE The study results suggest that HTPs as well as conventional combustible cigarettes can alter CpG methylation and gene transcription in lung epithelial cells.
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Affiliation(s)
- Ayami Sato
- Molecular Regulation of Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo 173-0015, Japan
| | - Akihito Ishigami
- Molecular Regulation of Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Tokyo 173-0015, Japan.
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Crooks I, Hollings M, Leverette R, Jordan K, Breheny D, Moore MM, Thorne D. A comparison of cigarette smoke test matrices and their responsiveness in the mouse lymphoma assay: A case study. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 879-880:503502. [PMID: 35914858 DOI: 10.1016/j.mrgentox.2022.503502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 05/22/2022] [Accepted: 05/24/2022] [Indexed: 06/15/2023]
Abstract
No cigarette smoke test matrix is without limitation, due to the complexity of the starting aerosol and phase to phase dynamics. It is impossible to capture all chemicals at the same level of efficiency, therefore, any test matrix will inadvertently or by design fractionate the test aerosol. This case study examines how four different test matrices derived from cigarette smoke can be directly compared. The test matrices assessed were as follows, total particulate matter (TPM), gas vapour phase (GVP), a combination of TPM + GVP and whole aerosol (WA). Here we use an example assay, the mouse lymphoma assay (MLA) to demonstrate that data generated across four cigarette smoke test matrices can be compared. The results show that all test matrices were able to induce positive mutational events, but with clear differences in the biological activity (both potency and toxicity) between them. TPM was deemed the most potent test article and by extension, the particulate phase is interpreted as the main driver of genotoxic induced responses in the MLA. However, the results highlight that the vapour phase is also active. MLA appeared responsive to WA, with potentially lower potency, compared to TPM approaches. However, this observation is caveated in that the WA approaches used for comparison were made on a newly developed experimental method using dose calculations. The TPM + GVP matrix had comparable activity to TPM alone, but interestingly induced a greater number of mutational events at comparable relative total growth (RTG) and TPM-equivalent doses when compared to other test matrices. In conclusion, this case study highlights the importance of understanding test matrices in response to the biological assay being assessed and we note that not all test matrices are equal.
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Affiliation(s)
- Ian Crooks
- B.A.T. (Investments) Limited, Regents Park Road, Millbrook, Southampton SO15 8TL, UK
| | - Michael Hollings
- Labcorp Early Development Laboratories Ltd., Harrogate, North Yorkshire HG3 1PY, UK
| | - Robert Leverette
- Reynolds American Inc, 950 Reynolds Blvd., Winston-Salem, NC 27105, USA
| | - Kristen Jordan
- Reynolds American Inc, 950 Reynolds Blvd., Winston-Salem, NC 27105, USA
| | - Damien Breheny
- B.A.T. (Investments) Limited, Regents Park Road, Millbrook, Southampton SO15 8TL, UK
| | | | - David Thorne
- B.A.T. (Investments) Limited, Regents Park Road, Millbrook, Southampton SO15 8TL, UK.
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Seo JE, Davis K, Malhi P, He X, Bryant M, Talpos J, Burks S, Mei N, Guo X. Genotoxicity evaluation using primary hepatocytes isolated from rhesus macaque (Macaca mulatta). Toxicology 2021; 462:152936. [PMID: 34509578 DOI: 10.1016/j.tox.2021.152936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/04/2021] [Accepted: 09/07/2021] [Indexed: 10/20/2022]
Abstract
Non-human primates (NHPs) have played a vital role in fundamental, pre-clinical, and translational studies because of their high physiological and genetic similarity to humans. Here, we report a method to isolate primary hepatocytes from the livers of rhesus macaques (Macaca mulatta) after in situ whole liver perfusion. Isolated primary macaque hepatocytes (PMHs) were treated with various compounds known to have different pathways of genotoxicity/carcinogenicity and the resulting DNA damage was evaluated using the high-throughput CometChip assay. The comet data were quantified using benchmark dose (BMD) modeling and the BMD50 values for treatments of PMHs were compared with those generated from primary human hepatocytes (PHHs) in our previous study (Seo et al. Arch Toxicol 2020, 2207-2224). The results showed that despite varying CYP450 enzyme activities, PMHs had the same sensitivity and specificity as PHHs in detecting four indirect-acting (i.e., requiring metabolic activation) and seven direct-acting genotoxicants/carcinogens, as well as five non-carcinogens that are negative or equivocal for genotoxicity in vivo. The BMD50 estimates and their confidence intervals revealed species differences for DNA damage potency, especially for direct-acting compounds. The present study provides a practical method for maximizing the use of animal tissues by isolating primary hepatocytes from NHPs. Our data support the use of PMHs as a reliable surrogate of PHHs for evaluating the genotoxic hazards of chemical substances for humans.
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Affiliation(s)
- Ji-Eun Seo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Kelly Davis
- Toxicologic Pathology Associates, Jefferson, AR 72079, USA
| | - Pritpal Malhi
- Toxicologic Pathology Associates, Jefferson, AR 72079, USA
| | - Xiaobo He
- Office of Scientific Coordination, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Matthew Bryant
- Office of Scientific Coordination, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - John Talpos
- Division of Neurotoxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Susan Burks
- Division of Neurotoxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA
| | - Xiaoqing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR 72079, USA.
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Meng F, Mei N, Yan J, Guo X, Richter PA, Chen T, De M. Comparative potency analysis of whole smoke solutions in the bacterial reverse mutation test. Mutagenesis 2021; 36:321-329. [PMID: 34131742 DOI: 10.1093/mutage/geab021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 06/11/2021] [Indexed: 11/13/2022] Open
Abstract
Short-term in vitro genotoxicity assays are useful tools to assess whether new and emerging tobacco products potentially have reduced toxicity. We previously demonstrated that potency ranking by benchmark dose (BMD) analysis quantitatively identifies differences among several known carcinogens and toxic chemicals representing different chemical classes found in cigarette smoke. In this study, six whole smoke solution (WSS) samples containing both the particulate and gas phases of tobacco smoke were generated from two commercial cigarette brands under different smoking-machine regimens. Sixty test cigarettes of each brand were machine-smoked according to the International Organization for Standardization (ISO) puffing protocol. In addition, either 60 or 20 test cigarettes of each brand were machine-smoked with the Canadian Intense (CI) puffing protocol. All six WSSs were evaluated in the bacterial reverse mutation (Ames) test using Salmonella typhimurium strains, in the presence or absence of S9 metabolic activation. The resulting S9-mediated mutagenic concentration-responses for the four WSSs from 60 cigarettes were then compared using BMD modeling analysis and the mutagenic potency expressed as number of revertants per μl of the WSS. The quantitative approaches resulted in a similar rank order of mutagenic potency for the Ames test in both TA98 and TA100. Under the conditions of this study, these results indicate that quantitative analysis of the Ames test data can discriminate between the mutagenic potencies of WSSs on the basis of smoking-machine regimen (ISO vs. CI), and cigarette product (differences in smoke chemistry).
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Affiliation(s)
- Fanxue Meng
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA.,7870 Reflection Cove Dr., Fort Myers, FL, USA
| | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Jian Yan
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Xiaoqing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Patricia A Richter
- Division of Nonclinical Science, Center for Tobacco Products, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA.,Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Tao Chen
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR 72079, USA
| | - Mamata De
- Division of Nonclinical Science, Center for Tobacco Products, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
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Mittelstaedt RA, Shaddock JG, Bhalli JA, Guo X, Li Y, Mei N, De M, Richter PA, Heflich RH. Differentiating between micronucleus dose-responses induced by whole cigarette smoke solutions with Benchmark Dose potency ranking. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2021; 866:503351. [PMID: 33985695 DOI: 10.1016/j.mrgentox.2021.503351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 02/22/2021] [Accepted: 03/19/2021] [Indexed: 01/20/2023]
Abstract
Dose-response modeling of in vitro micronucleus test (IVMNT) data was evaluated to determine if the approach has value in discriminating among different tobacco products. Micronucleus responses were generated in L5178Y/Tk+/- mouse lymphoma cells and TK6 human lymphoblastoid cells from a series of whole smoke solutions (WSSs) expected to have different levels of genotoxicity based on differences in their machine-generated smoke constituents. Eight WSSs were prepared by machine smoking different numbers (20 or 60) of two commercial cigarettes (Marlboro Silver or Red) under International Standardization Organization (ISO) or Health Canada Intense (HCI) smoking machine regimens and tested in the two cell lines with and without rat liver S9 activation. The S9-mediated IVMNT dose-response data from the WSSs were evaluated with PROAST software and Benchmark Doses (BMDs) and their upper and lower confidence intervals (CIs) were generated. IVMNT data differed based on the number and type of cigarettes smoked and smoking machine regimen. The IVMNT responses produced in mouse lymphoma cells generally were greater than in TK6 cells, but the ability of the two cell types to differentiate between WSSs was similar. The results indicate that BMD potency ranking was useful for differentiating between IVMNT responses.
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Affiliation(s)
- R A Mittelstaedt
- U.S. Food and Drug Administration, National Center for Toxicological Research, United States.
| | - J G Shaddock
- U.S. Food and Drug Administration, National Center for Toxicological Research, United States
| | - J A Bhalli
- U.S. Food and Drug Administration, National Center for Toxicological Research, United States
| | - X Guo
- U.S. Food and Drug Administration, National Center for Toxicological Research, United States
| | - Y Li
- U.S. Food and Drug Administration, National Center for Toxicological Research, United States
| | - N Mei
- U.S. Food and Drug Administration, National Center for Toxicological Research, United States
| | - M De
- U.S. Food and Drug Administration, Center for Tobacco Products, United States
| | - P A Richter
- U.S. Food and Drug Administration, Center for Tobacco Products, United States
| | - R H Heflich
- U.S. Food and Drug Administration, National Center for Toxicological Research, United States
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Hölzl-Armstrong L, Kucab JE, Zwart EP, Luijten M, Phillips DH, Arlt VM. Mutagenicity of N-hydroxy-4-aminobiphenyl in human TP53 knock-in (Hupki) mouse embryo fibroblasts. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2021; 62:252-264. [PMID: 33620775 DOI: 10.1002/em.22429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 01/30/2021] [Accepted: 02/17/2021] [Indexed: 06/12/2023]
Abstract
TP53 harbors somatic mutations in more than half of human tumors with some showing characteristic mutation spectra that have been linked to environmental exposures. In bladder cancer, a unique distribution of mutations amongst several codons of TP53 has been hypothesized to be caused by environmental carcinogens including 4-aminobiphenyl (4-ABP). 4-ABP undergoes metabolic activation to N-hydroxy-4-aminobiphenyl (N-OH-4-ABP) and forms pre-mutagenic adducts in DNA, of which N-(deoxyguanosin-8-yl)-4-ABP (dG-C8-4-ABP) is the major one. Human TP53 knock-in mouse embryo fibroblasts (HUFs) are a useful model to study the influence of environmental carcinogens on TP53-mutagenesis. By performing the HUF immortalization assay (HIMA) TP53-mutant HUFs are generated and mutations can be identified by sequencing. Here we studied the induction of mutations in human TP53 after treatment of primary HUFs with N-OH-4-ABP. In addition, mutagenicity in the bacterial lacZ reporter gene and the formation of dG-C8-4-ABP, measured by 32 P-postlabelling analysis, were determined in N-OH-4-ABP-treated primary HUFs. A total of 6% TP53-mutants were identified after treatment with 40 μM N-OH-4-ABP for 24 hr (n = 150) with G>C/C>G transversion being the main mutation type. The mutation spectrum found in the TP53 gene of immortalized N-OH-4-ABP-treated HUFs was unlike the one found in human bladder cancer. DNA adduct formation (~40 adducts/108 nucleotides) was detected after 24 hr treatment with 40 μM N-OH-4-ABP, but lacZ mutagenicity was not observed. Adduct levels decreased substantially (sixfold) after a 24 hr recovery period indicating that primary HUFs can efficiently repair the dG-C8-4-ABP adduct possibly before mutations are fixed. In conclusion, the observed difference in the N-OH-4-ABP-induced TP53 mutation spectrum to that observed in human bladder tumors do not support a role of 4-ABP in human bladder cancer development.
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Affiliation(s)
- Lisa Hölzl-Armstrong
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, UK
| | - Jill E Kucab
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, UK
| | - Edwin P Zwart
- Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - Mirjam Luijten
- Center for Health Protection, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands
| | - David H Phillips
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, UK
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, London, UK
- Toxicology Department, GAB Consulting GmbH, Heidelberg, Germany
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Hölzl-Armstrong L, Nævisdal A, Cox JA, Long AS, Chepelev NL, Phillips DH, White PA, Arlt VM. In vitro mutagenicity of selected environmental carcinogens and their metabolites in MutaMouse FE1 lung epithelial cells. Mutagenesis 2020; 35:453-463. [PMID: 33399867 PMCID: PMC7846080 DOI: 10.1093/mutage/geaa032] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 11/21/2020] [Indexed: 11/12/2022] Open
Abstract
Chemicals in commerce or under development must be assessed for genotoxicity; assessment is generally conducted using validated assays (e.g. Tk mouse lymphoma assay) as part of a regulatory process. Currently, the MutaMouse FE1 cell mutagenicity assay is undergoing validation for eventual use as a standard in vitro mammalian mutagenicity assay. FE1 cells have been shown to be metabolically competent with respect to some cytochrome P450 (CYP) isozymes; for instance, they can convert the human carcinogen benzo[a]pyrene into its proximate mutagenic metabolite. However, some contradictory results have been noted for other genotoxic carcinogens that require two-step metabolic activation (e.g. 2-acetylaminofluorene and 2-amino-3-methylimidazo[4,5-f]quinoxaline). Here, we examined three known or suspected human carcinogens, namely acrylamide, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 4-aminobiphenyl (4-ABP), together with their proximate metabolites (i.e. glycidamide, N-OH-PhIP and N-OH-4-ABP), to aid in the validation of the FE1 cell mutagenicity assay. Assessments of the parent compounds were conducted both in the presence and absence of an exogenous metabolic activation mixture S9; assessments of the metabolites were in the absence of S9. The most potent compound was N-OH-PhIP -S9, which elicited a mutant frequency (MF) level 5.3-fold over background at 5 µM. There was a 4.3-fold increase for PhIP +S9 at 5 µM, a 1.7-fold increase for glycidamide -S9 at 3.5 mM and a 1.5-fold increase for acrylamide +S9 at 4 mM. Acrylamide -S9 elicited a marginal 1.4-fold MF increase at 8 mM. Treatment with PhIP -S9, 4-ABP ±S9 and N-OH-4-ABP -S9 failed to elicit significant increases in lacZ MF with any of the treatment conditions tested. Gene expression of key CYP isozymes was quantified by RT-qPCR. Cyp1a1, 1a2 and 1b1 are required to metabolise PhIP and 4-ABP. Results showed that treatment with both compounds induced expression of Cyp1a1 and Cyp1b1 but not Cyp1a2. Cyp2e1, which catalyses the bioactivation of acrylamide to glycidamide, was not induced after acrylamide treatment. Overall, our results confirm that the FE1 cell mutagenicity assay has the potential for use alongside other, more traditional in vitro mutagenicity assays.
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Affiliation(s)
- Lisa Hölzl-Armstrong
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, London, UK
| | - Andrea Nævisdal
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, London, UK
| | - Julie A Cox
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Alexandra S Long
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Nikolai L Chepelev
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - David H Phillips
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, London, UK
| | - Paul A White
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King’s College London, London, UK
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Performance of high-throughput CometChip assay using primary human hepatocytes: a comparison of DNA damage responses with in vitro human hepatoma cell lines. Arch Toxicol 2020; 94:2207-2224. [PMID: 32318794 DOI: 10.1007/s00204-020-02736-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 04/06/2020] [Indexed: 10/24/2022]
Abstract
Primary human hepatocytes (PHHs) are considered the "gold standard" for evaluating hepatic metabolism and toxicity of xenobiotics. In the present study, we evaluated the genotoxic potential of four indirect-acting (requiring metabolic activation) and six direct-acting genotoxic carcinogens, one aneugen, and five non-carcinogens that are negative or equivocal for genotoxicity in vivo in cryopreserved PHHs derived from three individual donors. DNA damage was determined over a wide range of concentrations using the CometChip technology and the resulting dose-responses were quantified using benchmark dose (BMD) modeling. Following a 24-h treatment, nine out of ten genotoxic carcinogens produced positive responses in PHHs, while negative responses were found for hydroquinone, aneugen colchicine and five non-carcinogens. Overall, PHHs demonstrated a higher sensitivity (90%) for detecting DNA damage from genotoxic carcinogens than the sensitivities previously reported for HepG2 (60%) and HepaRG (70%) cells. Quantitative analysis revealed that most of the compounds produced comparable BMD10 values among the three types of hepatocytes, while PHHs and HepaRG cells produced similar BMD1SD values. Evidence of sex- and ethnicity-related interindividual variation in DNA damage responses was also observed in the PHHs. A literature search for in vivo Comet assay data conducted in rodent liver tissues demonstrated consistent positive/negative calls for the compounds tested between in vitro PHHs and in vivo animal models. These results demonstrate that CometChip technology can be applied using PHHs for human risk assessment and that PHHs had higher sensitivity than HepaRG cells for detecting genotoxic carcinogens in the CometChip assay.
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Li XL, Guo XQ, Wang HR, Chen T, Mei N. Aristolochic Acid-Induced Genotoxicity and Toxicogenomic Changes in Rodents. WORLD JOURNAL OF TRADITIONAL CHINESE MEDICINE 2020; 6:12-25. [PMID: 32258091 PMCID: PMC7110418 DOI: 10.4103/wjtcm.wjtcm_33_19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Aristolochic acid (AA) is a group of structurally related nitrophenanthrene carboxylic acids found in many plants that are widely used by many cultures as traditional herbal medicines. AA is a causative agent for Chinese herbs nephropathy, a term replaced later by AA nephropathy. Evidence indicates that AA is nephrotoxic, genotoxic, and carcinogenic in humans; and it also induces tumors in the forestomach, kidney, renal pelvis, urinary bladder, and lung of rats and mice. Therefore, plants containing AA have been classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer. In our laboratories, we have conducted a series of genotoxicity and toxicogenomic studies in the rats exposed to AA of 0.1–10 mg/kg for 12 weeks. Our results demonstrated that AA treatments induced DNA adducts and mutations in the kidney, liver, and spleen of rats, as well as significant alteration of gene expression in both its target and nontarget tissues. AA treatments altered mutagenesis- or carcinogenesis-related microRNA expression in rat kidney and resulted in significant changes in protein expression profiling. We also applied benchmark dose (BMD) modeling to the 3-month AA-induced genotoxicity data. The obtained BMDL10 (the lower 95% confidence interval of the BMD10 that is a 10% increase over the background level) for AA-induced mutations in the kidney of rats was about 7 μg/kg body weight per day. This review constitutes an overview of our investigations on AA-induced genotoxicity and toxicogenomic changes including gene expression, microRNA expression, and proteomics; and presents updated information focused on AA-induced genotoxicity in rodents.
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Affiliation(s)
- Xi-Lin Li
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
| | - Xiao-Qing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
| | - Hai-Rong Wang
- Tianjin Center for New Drug Safety Assessment and Research, Tianjin, China
| | - Tao Chen
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
| | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
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White PA, Luijten M, Mishima M, Cox JA, Hanna JN, Maertens RM, Zwart EP. In vitro mammalian cell mutation assays based on transgenic reporters: A report of the International Workshop on Genotoxicity Testing (IWGT). MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2019; 847:403039. [DOI: 10.1016/j.mrgentox.2019.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 03/26/2019] [Accepted: 04/06/2019] [Indexed: 02/07/2023]
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12
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Chen S, Li D, Zhang H, Yu D, Chen R, Zhang B, Tan Y, Niu Y, Duan H, Mai B, Chen S, Yu J, Luan T, Chen L, Xing X, Li Q, Xiao Y, Dong G, Niu Y, Aschner M, Zhang R, Zheng Y, Chen W. The development of a cell-based model for the assessment of carcinogenic potential upon long-term PM2.5 exposure. ENVIRONMENT INTERNATIONAL 2019; 131:104943. [PMID: 31295644 DOI: 10.1016/j.envint.2019.104943] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 06/08/2019] [Accepted: 06/18/2019] [Indexed: 06/09/2023]
Abstract
To assess the carcinogenic potential of PM2.5 exposure, we developed a cell-based experimental protocol to examine the cell transformation activity of PM2.5 samples from different regions in China. The seasonal ambient PM2.5 samples were collected from three megacities, Beijing (BJ), Wuhan (WH), and Guangzhou (GZ), from November 2016 to October 2017. The mean concentrations of PM2.5 were much higher in the winter season (BJ: 109.64 μg/m3, WH: 79.99 μg/m3, GZ: 49.99 μg/m3) than that in summer season (BJ: 42.40 μg/m3, WH: 25.82 μg/m3, GZ: 19.82 μg/m3). The organic extracts (OE) of PM2.5 samples from combined summer (S) (June, July, August) or winter (W) (November, December, January) seasons were subjected to characterization of chemical components. We treated human bronchial epithelial (HBE) cells expressing CYP1A1 (HBE-1A1) with PM2.5 samples at doses ranging from 0 to 100 μg/mL (0, 1.563, 3.125, 6.25, 12.5, 25, 50, 100 μg/mL) and determined the phenotype of malignant cell transformation. A dose-response relationship was analyzed by benchmark dose (BMD) modeling, and the potential were indicated by BMDL10. The order of the carcinogenic risk of seasonal PM2.5 samples from high to low was BJ-W, WH-W, GZ-W, WH-S, BJ-S, and GZ-S. Notably, we found that the alteration in the lung cancer-related biomarkers, KRAS, PTEN, p53, c-Myc, PCNA, pAKT/AKT, and pERK/ERK was congruent with the activity of cell transformation and the content of specific components of polycyclic aromatic hydrocarbon (PAHs) bound to PM2.5. Taken together, we have successfully developed a cell-based alternative model for the evaluation of potent carcinogenicity upon long-term PM2.5 exposure.
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Affiliation(s)
- Shen Chen
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Daochuan Li
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Haiyan Zhang
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Dianke Yu
- Department of Toxicology, School of Public Health, Qingdao University, Qingdao 266021, China
| | - Rui Chen
- Department of Toxicology and Sanitary Chemistry, School of Public Health, Capital Medical University, Beijing 100069, China
| | - Bin Zhang
- Wuhan Children's Hospital & Wuhan Maternal and Child Healthcare Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430015, China
| | - Yafei Tan
- Wuhan Children's Hospital & Wuhan Maternal and Child Healthcare Hospital, Tongji Medical College, Huazhong University of Science & Technology, Wuhan 430015, China
| | - Yong Niu
- Key Laboratory of Chemical Safety and Health, National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Huawei Duan
- Key Laboratory of Chemical Safety and Health, National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing 100050, China
| | - Bixian Mai
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Shejun Chen
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Jianzhen Yu
- Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Tiangang Luan
- School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Liping Chen
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Xiumei Xing
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Qiong Li
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Yongmei Xiao
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Guanghui Dong
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China
| | - Yujie Niu
- Department of Toxicology, School of Public Health, Hebei Medical University, Shijiazhuang 050017, China
| | - Michael Aschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Forchheimer 209, 1300 Morris Park Avenue, Bronx, NY 10461, USA
| | - Rong Zhang
- Department of Toxicology, School of Public Health, Hebei Medical University, Shijiazhuang 050017, China
| | - Yuxin Zheng
- Department of Toxicology and Sanitary Chemistry, School of Public Health, Capital Medical University, Beijing 100069, China
| | - Wen Chen
- Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China.
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13
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Guo X, Seo JE, Bryce SM, Tan JA, Wu Q, Dial SL, Moore MM, Mei N. Comparative Genotoxicity of TEMPO and 3 of Its Derivatives in Mouse Lymphoma Cells. Toxicol Sci 2019; 163:214-225. [PMID: 29385624 DOI: 10.1093/toxsci/kfy022] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
TEMPO (2, 2, 6, 6-tetramethylphiperidine-1-oxyl) and its derivatives are stable free radical nitroxides widely used in the field of chemistry, biology, and pharmacology. TEMPO was previously found to be mutagenic and to induce micronuclei in mammalian cells. In this study, we investigated and quantified the genotoxicity of 4 structurally similar nitroxides, TEMPO and 3 of its derivatives (4-hydroxy-TEMPO, 4-oxo-TEMPO, and 4-methoxy-TEMPO), using the mouse lymphoma assay (MLA) and Comet assay in L5178Y Tk+/- cells. The results showed that all tested nitroxides were cytotoxic and mutagenic in the MLA, both in the presence and absence of S9, with metabolic activation significantly enhancing the cytotoxicity and/or mutagenicity. In addition, the 4 nitroxides caused DNA-strand breakage. The mutagenicity and DNA damaging dose-responses of the test articles were compared using the PROAST benchmark dose software package. The potency ranking of the 4 nitroxides for mutagenicity was different from the ranking of the DNA damaging effects. The mode of action analysis by a multi-endpoint DNA damage pathway assay classified all 4 nitroxides as clastogens. In addition, the majority of the induced Tk mutants showed loss of heterozygosity at the Tk and D11Mit42 loci (ie, chromosome damage <31 Mbp). These results suggest that TEMPO and its 3 derivatives are cytotoxic and mutagenic in mouse lymphoma cells through a mechanism that involves strand breakage and large alterations to DNA. The potency rankings indicate that the different TEMPO derivatives vary in their mutagenic and DNA damaging potential.
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Affiliation(s)
- Xiaoqing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079
| | - Ji-Eun Seo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079
| | | | - Jenna A Tan
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079
| | - Qiangen Wu
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079
| | - Stacey L Dial
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079
| | - Martha M Moore
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079
| | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079
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14
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Seo JE, Tryndyak V, Wu Q, Dreval K, Pogribny I, Bryant M, Zhou T, Robison TW, Mei N, Guo X. Quantitative comparison of in vitro genotoxicity between metabolically competent HepaRG cells and HepG2 cells using the high-throughput high-content CometChip assay. Arch Toxicol 2019; 93:1433-1448. [PMID: 30788552 DOI: 10.1007/s00204-019-02406-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 01/31/2019] [Indexed: 12/18/2022]
Abstract
In vitro genotoxicity testing that employs metabolically active human cells may be better suited for evaluating human in vivo genotoxicity than current bacterial or non-metabolically active mammalian cell systems. In the current study, 28 compounds, known to have different genotoxicity and carcinogenicity modes of action (MoAs), were evaluated over a wide range of concentrations for the ability to induce DNA damage in human HepG2 and HepaRG cells. DNA damage dose-responses in both cell lines were quantified using a combination of high-throughput high-content (HTHC) CometChip technology and benchmark dose (BMD) quantitative approaches. Assays of metabolic activity indicated that differentiated HepaRG cells had much higher levels of cytochromes P450 activity than did HepG2 cells. DNA damage was observed for four and two out of five indirect-acting genotoxic carcinogens in HepaRG and HepG2 cells, respectively. Four out of seven direct-acting carcinogens were positive in both cell lines, with two of the three negatives being genotoxic mainly through aneugenicity. The four chemicals positive in both cell lines generated HTHC Comet data in HepaRG and HepG2 cells with comparable BMD values. All the non-genotoxic compounds, including six non-genotoxic carcinogens, were negative in HepaRG cells; five genotoxic non-carcinogens also were negative. Our results indicate that the HTHC CometChip assay detects a greater proportion of genotoxic carcinogens requiring metabolic activation (i.e., indirect carcinogens) when conducted with HepaRG cells than with HepG2 cells. In addition, BMD genotoxicity potency estimate is useful for quantitatively evaluating CometChip assay data in a scientifically rigorous manner.
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Affiliation(s)
- Ji-Eun Seo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, 72079, USA
| | - Volodymyr Tryndyak
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR, 72079, USA
| | - Qiangen Wu
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR, 72079, USA
| | - Kostiantyn Dreval
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR, 72079, USA.,Department of Internal Medicine, Division of Molecular Medicine, Program in Cancer Genetics, Epigenetics and Genomics, University of New Mexico Comprehensive Cancer Center, Albuquerque, NM, 87131, USA
| | - Igor Pogribny
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR, 72079, USA
| | - Matthew Bryant
- Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, AR, 72079, USA
| | - Tong Zhou
- Center for Veterinary Medicine, U.S. Food and Drug Administration, Rockville, MD, 20855, USA
| | - Timothy W Robison
- Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, 20993, USA
| | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, 72079, USA
| | - Xiaoqing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, 72079, USA.
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15
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Mittelstaedt RA, Dobrovolsky VN, Revollo JR, Pearce MG, Wang Y, Dad A, McKinzie PB, Rosenfeldt H, Yucesoy B, Yeager R, Hu SC, Tang Y, Min S, Kang HK, Yang DJ, Basavarajappa M, Heflich RH. Evaluation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) mutagenicity using in vitro and in vivo Pig-a assays. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2019; 837:65-72. [PMID: 30595212 DOI: 10.1016/j.mrgentox.2018.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 10/26/2018] [Accepted: 10/26/2018] [Indexed: 02/06/2023]
Abstract
4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a genotoxic carcinogen found in tobacco and tobacco smoke. Several in vitro and in vivo assays have been used for evaluating the genotoxicity of tobacco smoke and tobacco smoke constituents like NNK, yet it is not clear which in vitro assays are most appropriate for extrapolating the in vitro responses of these test agents to animal models and humans. The Pig-a gene mutation assay can be performed in vitro, in laboratory animals, and in humans, a potential benefit in estimating in vivo responses from in vitro data. In the current study we used Pig-a as a reporter of gene mutation both in vitro, in L5178Y/Tk+/- cells, and in vivo, in Sprague-Dawley rats. NNK significantly increased Pig-a mutant frequency in L5178Y/Tk+/- cells, but only at concentrations of 100 μg/ml and greater, and only in the presence of S9 activation. Pig-a mutations in L5178Y/Tk+/- cells were detected in 80% of the NNK-induced mutants, with the predominate mutation being G→A transition; vehicle control mutants contained deletions. In the in vivo study, rats were exposed to NNK daily for 90 days by inhalation, a common route of exposure to NNK for humans. Although elevated mutant frequencies were detected, these responses were not clearly associated with NNK exposure, so that overall, the in vivo Pig-a assays were negative. Thus, while NNK induces mutations in the in vitro Pig-a assay, the in vivo Pig-a assay has limited ability to detect NNK mutagenicity under conditions relevant to NNK exposure in smokers.
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Affiliation(s)
- Roberta A Mittelstaedt
- U.S. Food and Drug Administration, Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, USA
| | - Vasily N Dobrovolsky
- U.S. Food and Drug Administration, Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, USA
| | - Javier R Revollo
- U.S. Food and Drug Administration, Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, USA
| | - Mason G Pearce
- U.S. Food and Drug Administration, Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, USA
| | - Yiying Wang
- U.S. Food and Drug Administration, Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, USA
| | - Azra Dad
- U.S. Food and Drug Administration, Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, USA
| | - Page B McKinzie
- U.S. Food and Drug Administration, Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, USA
| | - Hans Rosenfeldt
- U.S. Food and Drug Administration, Division of Nonclinical Science, Office of Science, Center for Tobacco Products, USA
| | - Berran Yucesoy
- U.S. Food and Drug Administration, Division of Nonclinical Science, Office of Science, Center for Tobacco Products, USA
| | - Raymond Yeager
- U.S. Food and Drug Administration, Division of Nonclinical Science, Office of Science, Center for Tobacco Products, USA
| | - Shu-Chieh Hu
- U.S. Food and Drug Administration, Inhalcore, Office of Scientific Coordination, National Center for Toxicological Research, USA
| | - Yunan Tang
- U.S. Food and Drug Administration, Inhalcore, Office of Scientific Coordination, National Center for Toxicological Research, USA
| | - Seonggi Min
- U.S. Food and Drug Administration, Inhalcore, Office of Scientific Coordination, National Center for Toxicological Research, USA
| | - Hyun-Ki Kang
- U.S. Food and Drug Administration, Inhalcore, Office of Scientific Coordination, National Center for Toxicological Research, USA
| | - Dong-Jin Yang
- U.S. Food and Drug Administration, Inhalcore, Office of Scientific Coordination, National Center for Toxicological Research, USA
| | - Mallikarjuna Basavarajappa
- U.S. Food and Drug Administration, Inhalcore, Office of Scientific Coordination, National Center for Toxicological Research, USA
| | - Robert H Heflich
- U.S. Food and Drug Administration, Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, USA.
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16
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Guo X, Pan B, Seo JE, Chen Y, Yan J, Mei N, Chen T. Whole genome sequencing analysis of small and large colony mutants from the mouse lymphoma assay. Arch Toxicol 2018; 92:3585-3595. [DOI: 10.1007/s00204-018-2318-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 09/19/2018] [Indexed: 11/25/2022]
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17
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Guo X, Mei N. Benchmark Dose Modeling of In Vitro Genotoxicity Data: a Reanalysis. Toxicol Res 2018; 34:303-310. [PMID: 30370005 PMCID: PMC6195882 DOI: 10.5487/tr.2018.34.4.303] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Revised: 08/16/2018] [Accepted: 08/30/2018] [Indexed: 01/22/2023] Open
Abstract
The methods of applied genetic toxicology are changing from qualitative hazard identification to quantitative risk assessment. Recently, quantitative analysis with point of departure (PoD) metrics and benchmark dose (BMD) modeling have been applied to in vitro genotoxicity data. Two software packages are commonly used for BMD analysis. In previous studies, we performed quantitative dose-response analysis by using the PROAST software to quantitatively evaluate the mutagenicity of four piperidine nitroxides with various substituent groups on the 4-position of the piperidine ring and six cigarette whole smoke solutions (WSSs) prepared by bubbling machine-generated whole smoke. In the present study, we reanalyzed the obtained genotoxicity data by using the EPA's BMD software (BMDS) to evaluate the inter-platform quantitative agreement of the estimates of genotoxic potency. We calculated the BMDs for 10%, 50%, and 100% (i.e., a two-fold increase), and 200% increases over the concurrent vehicle controls to achieve better discrimination of the dose-responses, along with their BMDLs (the lower 95% confidence interval of the BMD) and BMDUs (the upper 95% confidence interval of the BMD). The BMD values and rankings estimated in this study by using the EPA's BMDS were reasonably similar to those calculated in our previous studies by using PROAST. These results indicated that both software packages were suitable for dose-response analysis using the mouse lymphoma assay and that the BMD modeling results from these software packages produced comparable rank orders of the mutagenic potency.
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Affiliation(s)
- Xiaoqing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
| | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, AR, USA
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18
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Linhares DPS, Garcia PV, Silva C, Barroso J, Kazachkova N, Pereira R, Lima M, Camarinho R, Ferreira T, Dos Santos Rodrigues A. DNA damage in oral epithelial cells of individuals chronically exposed to indoor radon ( 222Rn) in a hydrothermal area. ENVIRONMENTAL GEOCHEMISTRY AND HEALTH 2018; 40:1713-1724. [PMID: 27830439 DOI: 10.1007/s10653-016-9893-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 10/27/2016] [Indexed: 06/06/2023]
Abstract
Hydrothermal areas are potentially hazardous to humans as volcanic gases such as radon (222Rn) are continuously released from soil diffuse degassing. Exposure to radon is estimated to be the second leading cause of lung cancer, but little is known about radon health-associated risks in hydrothermal regions. This cross-sectional study was designed to evaluate the DNA damage in the buccal epithelial cells of individuals chronically exposed to indoor radon in a volcanic area (Furnas volcano, Azores, Portugal) with a hydrothermal system. Buccal epithelial cells were collected from 33 individuals inhabiting the hydrothermal area (Ribeira Quente village) and from 49 individuals inhabiting a non-hydrothermal area (Ponta Delgada city). Indoor radon was measured with Ramon 2.2 detectors. Chromosome damage was measured by micronucleus cytome assay, and RAPD-PCR was used as a complementary tool to evaluate DNA damage, using three 10-mer primers (D11, F1 and F12). Indoor radon concentration correlated positively with the frequency of micronucleated cells (r s = 0.325, p = 0.003). Exposure to radon is a risk factor for the occurrence micronucleated cells in the inhabitants of the hydrothermal area (RR = 1.71; 95% CI, 1.2-2.4; p = 0.003). One RAPD-PCR primer (F12) produced differences in the banding pattern, a fact that can indicate its potential for detecting radon-induced specific genomic alterations. The observed association between chronic exposure to indoor radon and the occurrence of chromosome damage in human oral epithelial cells evidences the usefulness of biological surveillance to assess mutations involved in pre-carcinogenesis in hydrothermal areas, reinforcing the need for further studies with human populations living in these areas.
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Affiliation(s)
- Diana Paula Silva Linhares
- Department of Biology, University of the Azores, Rua da Mãe de Deus, Apartado 1422, 9501-801, Ponta Delgada, Azores, Portugal.
- CVARG, Center for Volcanology and Geological Risks Assessment, University of the Azores, 9501-801, Ponta Delgada, Azores, Portugal.
| | - Patrícia Ventura Garcia
- Department of Biology, University of the Azores, Rua da Mãe de Deus, Apartado 1422, 9501-801, Ponta Delgada, Azores, Portugal
- cE3c, Centre for Ecology Evolution and Environmental Changes and Azorean Biodiversity Group, University of the Azores, 9501-801, Ponta Delgada, Azores, Portugal
| | - Catarina Silva
- CVARG, Center for Volcanology and Geological Risks Assessment, University of the Azores, 9501-801, Ponta Delgada, Azores, Portugal
- CIVISA, Center for Information and Seismovolcanic Surveillance of the Azores, University of the Azores, Ponta Delgada, Portugal
| | - Joana Barroso
- Department of Biology, University of the Azores, Rua da Mãe de Deus, Apartado 1422, 9501-801, Ponta Delgada, Azores, Portugal
| | - Nadya Kazachkova
- Department of Biology, University of the Azores, Rua da Mãe de Deus, Apartado 1422, 9501-801, Ponta Delgada, Azores, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
| | - Rui Pereira
- Department of Biology, University of the Azores, Rua da Mãe de Deus, Apartado 1422, 9501-801, Ponta Delgada, Azores, Portugal
| | - Manuela Lima
- Department of Biology, University of the Azores, Rua da Mãe de Deus, Apartado 1422, 9501-801, Ponta Delgada, Azores, Portugal
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
- Institute for Molecular and Cell Biology (IBMC), University of Porto, Porto, Portugal
| | - Ricardo Camarinho
- Department of Biology, University of the Azores, Rua da Mãe de Deus, Apartado 1422, 9501-801, Ponta Delgada, Azores, Portugal
| | - Teresa Ferreira
- Department of Geosciences, University of the Azores, 9501-801, Ponta Delgada, Azores, Portugal
- CVARG, Center for Volcanology and Geological Risks Assessment, University of the Azores, 9501-801, Ponta Delgada, Azores, Portugal
| | - Armindo Dos Santos Rodrigues
- Department of Biology, University of the Azores, Rua da Mãe de Deus, Apartado 1422, 9501-801, Ponta Delgada, Azores, Portugal
- CVARG, Center for Volcanology and Geological Risks Assessment, University of the Azores, 9501-801, Ponta Delgada, Azores, Portugal
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19
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Crooks I, Neilson L, Scott K, Reynolds L, Oke T, Forster M, Meredith C, McAdam K, Proctor C. Evaluation of flavourings potentially used in a heated tobacco product: Chemical analysis, in vitro mutagenicity, genotoxicity, cytotoxicity and in vitro tumour promoting activity. Food Chem Toxicol 2018; 118:940-952. [PMID: 29879435 DOI: 10.1016/j.fct.2018.05.058] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 05/22/2018] [Accepted: 05/25/2018] [Indexed: 10/14/2022]
Abstract
We designed a novel tobacco-heating product (THP) that heats tobacco to release nicotine and aerosolised components, such as glycerol and tobacco volatiles from a tobacco rod (Neostik). Heating tobacco significantly reduces levels of combustion-derived toxicants in the aerosol compared to cigarette smoke. This study was conducted to determine whether the inclusion of potential flavourings in the THP would add to the levels of toxicants in the emissions or alter in vitro responses. Levels of measured toxicants were similar in the flavoured and unflavoured Neostik emissions and significantly less than emissions from the reference cigarette, 3R4F. No mutagenicity was observed with the Neostiks in the Ames test or in the mouse lymphoma assay. There was evidence of a weak genotoxic response in the in vitro micronucleus test using V79 cells from both Neostiks and these responses were less than 3R4F. They did not show tumour-promoting potential in the Bhas 42 cell transformation assay and were not cytotoxic in the Neutral Red uptake assay. 3R4F elicited toxic responses in all assays at significantly lower concentrations. The addition of flavourings to the Neostik tested did not alter the chemical profile of THP emissions or change in vitro responses relative to the unflavoured Neostik.
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Affiliation(s)
- Ian Crooks
- Research and Development, British American Tobacco Investments Ltd., Regents Park Road, Southampton, Hampshire, SO15 8TL, UK.
| | - Louise Neilson
- Research and Development, British American Tobacco Investments Ltd., Regents Park Road, Southampton, Hampshire, SO15 8TL, UK
| | - Ken Scott
- Research and Development, British American Tobacco Investments Ltd., Regents Park Road, Southampton, Hampshire, SO15 8TL, UK
| | - Lorna Reynolds
- Research and Development, British American Tobacco Investments Ltd., Regents Park Road, Southampton, Hampshire, SO15 8TL, UK
| | - Tobi Oke
- Research and Development, British American Tobacco Investments Ltd., Regents Park Road, Southampton, Hampshire, SO15 8TL, UK
| | - Mark Forster
- Research and Development, British American Tobacco Investments Ltd., Regents Park Road, Southampton, Hampshire, SO15 8TL, UK
| | - Clive Meredith
- Research and Development, British American Tobacco Investments Ltd., Regents Park Road, Southampton, Hampshire, SO15 8TL, UK
| | - Kevin McAdam
- Research and Development, British American Tobacco Investments Ltd., Regents Park Road, Southampton, Hampshire, SO15 8TL, UK
| | - Chris Proctor
- Research and Development, British American Tobacco Investments Ltd., Regents Park Road, Southampton, Hampshire, SO15 8TL, UK
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20
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Guo X, Heflich RH, Dial SL, De M, Richter PA, Mei N. Quantitative differentiation of whole smoke solution-induced mutagenicity in the mouse lymphoma assay. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2018; 59:103-113. [PMID: 29119619 PMCID: PMC8142256 DOI: 10.1002/em.22151] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 10/02/2017] [Accepted: 10/04/2017] [Indexed: 06/07/2023]
Abstract
In vitro genotoxicity dose-response data have been investigated for their utility in modeling and assessing potential differences in mutagenic responses between machine-generated whole smoke solutions (WSSs) from combusted cigarette tobacco products. Our previous study observed that potency ranking by benchmark dose (BMD) analysis was a useful modeling approach for quantitative assessment of differences between the mutagenicity of several structurally diverse chemical constituents of cigarette smoke. To follow-up on these observations, we used the mouse lymphoma assay (MLA) to evaluate the mutagenicity of WSSs prepared from two commercial cigarettes smoked under two different smoking machine regimens. L5178Y cells were exposed to ≥5 concentrations of each WSS for 4 hr ± S9 activation. S9 reduced the cytotoxicity and enhanced the mutagenicity of the WSSs. The resulting S9-mediated mutagenicity dose-responses were compared between test articles using BMD analysis, the lowest dose exceeding the Global Evaluation Factor, the no observed or lowest observed genotoxic effect level, and the mutagenic potency. The BMD10 , BMD50 , BMD100 , and BMD200 , indicating a 10%, 50%, 100%, or 200% increase in the background mutant frequency, respectively, were calculated using the PROAST software package. Overall, the quantitative approaches resulted in a similar rank order of mutagenic potency for the MLA tested WSSs, with potency increasing with the level of tar. The BMD approach using covariate analysis produced the most informative comparisons. Differences in potency were associated with the number of cigarettes smoked, the cigarette product smoked, and the smoking machine protocol used to prepare the sample. Under the conditions of this study, these results suggest that our hypothesis of modeling MLA data using the BMD approach to quantitatively discriminate between the mutagenic potential of WSSs from combustible cigarettes might be an useful method. Environ. Mol. Mutagen. 59:103-113, 2018. Published 2017. This article is a US Government work and is in the public domain in the USA.
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Affiliation(s)
- Xiaoqing Guo
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas
| | - Robert H. Heflich
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas
| | - Stacey L. Dial
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas
| | - Mamata De
- Center for Tobacco Products, Silver Spring, Maryland
| | | | - Nan Mei
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Jefferson, Arkansas
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21
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Tommasi S, Bates SE, Behar RZ, Talbot P, Besaratinia A. Limited mutagenicity of electronic cigarettes in mouse or human cells in vitro. Lung Cancer 2017; 112:41-46. [PMID: 29191599 DOI: 10.1016/j.lungcan.2017.07.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 07/25/2017] [Accepted: 07/30/2017] [Indexed: 10/19/2022]
Abstract
OBJECTIVES Electronic cigarettes (e-cig), which are promoted as safe alternatives to tobacco cigarettes or as aides to smoking cessation, are becoming increasingly popular among adult chronic smokers and adolescents experimenting with tobacco products. Despite the known presence of toxicants and carcinogens in e-cig liquid and vapor, the possible carcinogenic effects of e-cig use in humans are unknown. MATERIALS AND METHODS We have utilized two validated in vitro model systems to investigate whether e-cig vapor induces mutation in mouse or human cells. We have exposed transgenic mouse fibroblasts in vitro to e-cig vapor extracts prepared from three popular brands, and determined the induction of mutagenesis in a reporter gene, the cII transgene. Furthermore, we have treated the pSP189 plasmid with e-cig vapor extract, transfected human fibroblast cells with the e-cig-treated plasmid, and screened for the induced mutations in the supF gene. RESULTS AND CONCLUSION We observed no statistically significant increases in relative mutant frequency in the cII transgene or supF gene in the e-cig treated mouse or human cells, respectively. Our data indicate that e-cig vapor extracts from the selected brands and at concentrations tested in this study have limited mutagenicity in both mouse and human cells in vitro.
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Affiliation(s)
- Stella Tommasi
- Department of Preventive Medicine, USC Keck School of Medicine, University of Southern California, M/C 9603, Los Angeles, CA 90033, USA
| | - Steven E Bates
- Department of Cancer Biology, Beckman Research Institute at City of Hope , Duarte, CA, 91010, USA
| | - Rachel Z Behar
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Prue Talbot
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Ahmad Besaratinia
- Department of Preventive Medicine, USC Keck School of Medicine, University of Southern California, M/C 9603, Los Angeles, CA 90033, USA.
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22
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White PA, Johnson GE. Genetic toxicology at the crossroads-from qualitative hazard evaluation to quantitative risk assessment. Mutagenesis 2016; 31:233-7. [PMID: 27000791 DOI: 10.1093/mutage/gew011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Applied genetic toxicology is undergoing a transition from qualitative hazard identification to quantitative dose-response analysis and risk assessment. To facilitate this change, the Health and Environmental Sciences Institute (HESI) Genetic Toxicology Technical Committee (GTTC) sponsored a workshop held in Lancaster, UK on July 10-11, 2014. The event included invited speakers from several institutions and the contents was divided into three themes-1: Point-of-departure Metrics for Quantitative Dose-Response Analysis in Genetic Toxicology; 2: Measurement and Estimation of Exposures for Better Extrapolation to Humans and 3: The Use of Quantitative Approaches in Genetic Toxicology for human health risk assessment (HHRA). A host of pertinent issues were discussed relating to the use of in vitro and in vivo dose-response data, the development of methods for in vitro to in vivo extrapolation and approaches to use in vivo dose-response data to determine human exposure limits for regulatory evaluations and decision-making. This Special Issue, which was inspired by the workshop, contains a series of papers that collectively address topics related to the aforementioned themes. The Issue includes contributions that collectively evaluate, describe and discuss in silico, in vitro, in vivo and statistical approaches that are facilitating the shift from qualitative hazard evaluation to quantitative risk assessment. The use and application of the benchmark dose approach was a central theme in many of the workshop presentations and discussions, and the Special Issue includes several contributions that outline novel applications for the analysis and interpretation of genetic toxicity data. Although the contents of the Special Issue constitutes an important step towards the adoption of quantitative methods for regulatory assessment of genetic toxicity, formal acceptance of quantitative methods for HHRA and regulatory decision-making will require consensus regarding the relationships between genetic damage and disease, and the concomitant ability to use genetic toxicity results per se.
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Affiliation(s)
| | - George E Johnson
- Institute of Life Science, Swansea University Medical School, Singleton Park, Swansea SA3 5DE, UK
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