1
|
Salimi A, Haddadi S, Khezri S, Asgari B, Pourgholi M. Vanillic acid protects mortality and toxicity induced by N-ethyl-N-nitrosourea in mice; in vivo model of chronic lymphocytic leukemia. Toxicol Rep 2024; 12:389-396. [PMID: 38590344 PMCID: PMC10999465 DOI: 10.1016/j.toxrep.2024.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/13/2024] [Accepted: 03/27/2024] [Indexed: 04/10/2024] Open
Abstract
Alkylating agents such as N-Ethyl-N-Nitrosourea (ENU) are ubiquitous within living cells and in the environment. This study designed to evaluate the chemopreventive activity of vanillic acid on ENU-induced toxicity and carcinogenesis in mice as an animal model of chronic lymphocytic leukemia (CLL). The female, Swiss albino mice were divided into three groups each with 7 mice, group I received normal saline, group II, mice received ENU at a dose of 80 mg/kg body weight i.p. to induce CLL on the 31th day of the study, and group III, the mice pretreated with vanillic acid at a dose of 20 mg/kg body weight/day, i.p. up to 30 days and received ENU. The animals were monitored for weight changes and mortality during 120 days, and then were sacrificed for isolation of lymphocytes, as target cells in CLL. Cellular parameters like reactive oxygen species (ROS) formation, malondialdehyde (MDA) production, depletion of glutathione (GSH), mitochondrial membrane potential (MMP) and lysosomal membrane integrity were studied. We found that pretreatment with vanillic acid significantly increased the survival of mice up to 57%, delay in death time (30%) and prevented weight changes after exposure to ENU. In addition, it was found that vanillic acid protected ROS formation, lipid peroxidation mitochondrial dysfunction, and lysosomal membrane destabilization in isolated lymphocytes. These data suggest that vanillic acid exhibited significant protection against ENU-induced toxicity and carcinogenicity, which might be related to the protection of the mitochondria and lysosomes and the reduction of ROS formation and oxidative stress.
Collapse
Affiliation(s)
- Ahmad Salimi
- Department of Pharmacology and Toxicology, School of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
- Traditional Medicine and Hydrotherapy Research Center, Ardabil University of Medical Sciences, Iran
| | - Shadi Haddadi
- Department of Pharmacology and Toxicology, School of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
- Students Research Committee, Faculty of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Saleh Khezri
- Department of Pharmacology and Toxicology, School of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Bahare Asgari
- Department of Pharmacology and Toxicology, School of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
- Students Research Committee, Faculty of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Mahshad Pourgholi
- Department of Pharmacology and Toxicology, School of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
- Students Research Committee, Faculty of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
| |
Collapse
|
2
|
Smith-Roe SL, Hobbs CA, Hull V, Todd Auman J, Recio L, Streicker MA, Rivas MV, Pratt GA, Lo FY, Higgins JE, Schmidt EK, Williams LN, Nachmanson D, Valentine Iii CC, Salk JJ, Witt KL. Adopting duplex sequencing technology for genetic toxicity testing: A proof-of-concept mutagenesis experiment with N-ethyl-N-nitrosourea (ENU)-exposed rats. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2023; 891:503669. [PMID: 37770135 PMCID: PMC10539650 DOI: 10.1016/j.mrgentox.2023.503669] [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: 05/06/2023] [Revised: 07/31/2023] [Accepted: 08/01/2023] [Indexed: 09/30/2023]
Abstract
Duplex sequencing (DS) is an error-corrected next-generation sequencing method in which molecular barcodes informatically link PCR-copies back to their source DNA strands, enabling computational removal of errors in consensus sequences. The resulting background of less than one artifactual mutation per 107 nucleotides allows for direct detection of somatic mutations. TwinStrand Biosciences, Inc. has developed a DS-based mutagenesis assay to sample the rat genome, which can be applied to genetic toxicity testing. To evaluate this assay for early detection of mutagenesis, a time-course study was conducted using male Hsd:Sprague Dawley SD rats (3 per group) administered a single dose of 40 mg/kg N-ethyl-N-nitrosourea (ENU) via gavage, with mutation frequency (MF) and spectrum analyzed in stomach, bone marrow, blood, and liver tissues at 3 h, 24 h, 7 d, and 28 d post-exposure. Significant increases in MF were observed in ENU-exposed rats as early as 24 h for stomach (site of contact) and bone marrow (a highly proliferative tissue) and at 7 d for liver and blood. The canonical, mutational signature of ENU was established by 7 d post-exposure in all four tissues. Interlaboratory analysis of a subset of samples from different tissues and time points demonstrated remarkable reproducibility for both MF and spectrum. These results demonstrate that MF and spectrum can be evaluated successfully by directly sequencing targeted regions of DNA obtained from various tissues, a considerable advancement compared to currently used in vivo gene mutation assays.
Collapse
Affiliation(s)
| | - Cheryl A Hobbs
- Integrated Laboratory Systems, LLC (An Inotiv Company), Research Triangle Park, NC, USA
| | - Victoria Hull
- Integrated Laboratory Systems, LLC (An Inotiv Company), Research Triangle Park, NC, USA
| | - J Todd Auman
- Integrated Laboratory Systems, LLC (An Inotiv Company), Research Triangle Park, NC, USA
| | - Leslie Recio
- Integrated Laboratory Systems, LLC (An Inotiv Company), Research Triangle Park, NC, USA
| | - Michael A Streicker
- Integrated Laboratory Systems, LLC (An Inotiv Company), Research Triangle Park, NC, USA
| | - Miriam V Rivas
- Integrated Laboratory Systems, LLC (An Inotiv Company), Research Triangle Park, NC, USA
| | | | - Fang Yin Lo
- TwinStrand Biosciences, Inc., Seattle, WA, USA
| | | | | | | | | | | | | | - Kristine L Witt
- Division of Translational Toxicology, NIEHS, Research Triangle Park, NC, USA
| |
Collapse
|
3
|
Kozal JS, Lynch HN, Klapacz J, Schoeny RS, Jean PA, Maier A. Mode of action assessment for propylene dichloride as a human carcinogen. Chem Biol Interact 2023; 382:110382. [PMID: 36754223 DOI: 10.1016/j.cbi.2023.110382] [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: 08/02/2022] [Revised: 01/16/2023] [Accepted: 02/04/2023] [Indexed: 02/09/2023]
Abstract
As part of a systematic review of the non-cancer and cancer hazards of propylene dichloride (PDC), with a focus on potential carcinogenicity in workers following inhalation exposures, we determined that a mode of action (MOA)-centric framing of cancer effects was warranted. In our MOA analysis, we systematically reviewed the available mechanistic evidence for PDC-induced carcinogenesis, and we mapped biologically plausible MOA pathways and key events (KEs), as guided by the International Programme on Chemical Safety (IPCS)-MOA framework. For the identified pathways and KEs, biological concordance, essentiality of KEs, concordance of empirical observations among KEs, consistency, and analogy were evaluated. The results of this analysis indicate that multiple biologically plausible pathways may contribute to the cancer MOA for PDC, but that the relevant pathways vary by exposure route and level, tissue type, and species; further, more than one pathway may occur concurrently at high exposure levels. While several important data gaps exist, evidence from in vitro mechanistic studies, in vivo experimental animal studies, and ex vivo human tumor tissue analyses indicates that the predominant MOA pathway likely involves saturation of cytochrome p450 2E1 (CYP2E1)-glutathione (GSH) detoxification (molecular initiating event; MIE), accumulation of CYP2E1-oxidative metabolites, cytotoxicity, chronic tissue damage and inflammation, and ultimately tumor formation. Tumors may occur through several subsets of inflammatory KEs, including inflammation-induced aberrant expression of activation-induced cytidine deaminase (AID), which causes DNA strand breaks and mutations and can lead to tumors with a characteristic mutational signature found in occupational cholangiocarcinoma. Dose concordance analysis showed that low-dose mutagenicity (from any pathway) is not a driving MOA, and that prevention of target tissue damage and inflammation (associated with saturation of CYP2E1-GSH detoxification) is expected to also prevent the cascade of processes responsible for tumor formation.
Collapse
Affiliation(s)
| | | | - Joanna Klapacz
- Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, MI, 48674, USA
| | | | | | | |
Collapse
|
4
|
Dodge AE, LeBlanc DPM, Zhou G, Williams A, Meier MJ, Van P, Lo FY, Valentine Iii CC, Salk JJ, Yauk CL, Marchetti F. Duplex sequencing provides detailed characterization of mutation frequencies and spectra in the bone marrow of MutaMouse males exposed to procarbazine hydrochloride. Arch Toxicol 2023; 97:2245-2259. [PMID: 37341741 PMCID: PMC10322784 DOI: 10.1007/s00204-023-03527-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/17/2023] [Indexed: 06/22/2023]
Abstract
Mutagenicity testing is an essential component of health safety assessment. Duplex Sequencing (DS), an emerging high-accuracy DNA sequencing technology, may provide substantial advantages over conventional mutagenicity assays. DS could be used to eliminate reliance on standalone reporter assays and provide mechanistic information alongside mutation frequency (MF) data. However, the performance of DS must be thoroughly assessed before it can be routinely implemented for standard testing. We used DS to study spontaneous and procarbazine (PRC)-induced mutations in the bone marrow (BM) of MutaMouse males across a panel of 20 diverse genomic targets. Mice were exposed to 0, 6.25, 12.5, or 25 mg/kg-bw/day for 28 days by oral gavage and BM sampled 42 days post-exposure. Results were compared with those obtained using the conventional lacZ viral plaque assay on the same samples. DS detected significant increases in mutation frequencies and changes to mutation spectra at all PRC doses. Low intra-group variability within DS samples allowed for detection of increases at lower doses than the lacZ assay. While the lacZ assay initially yielded a higher fold-change in mutant frequency than DS, inclusion of clonal mutations in DS mutation frequencies reduced this discrepancy. Power analyses suggested that three animals per dose group and 500 million duplex base pairs per sample is sufficient to detect a 1.5-fold increase in mutations with > 80% power. Overall, we demonstrate several advantages of DS over classical mutagenicity assays and provide data to support efforts to identify optimal study designs for the application of DS as a regulatory test.
Collapse
Affiliation(s)
- Annette E Dodge
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada
| | - Danielle P M LeBlanc
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Gu Zhou
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Andrew Williams
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Matthew J Meier
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Phu Van
- TwinStrand Biosciences Inc., Seattle, Washington, USA
| | - Fang Yin Lo
- TwinStrand Biosciences Inc., Seattle, Washington, USA
| | | | - Jesse J Salk
- TwinStrand Biosciences Inc., Seattle, Washington, USA
| | - Carole L Yauk
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada.
- Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| | - Francesco Marchetti
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada.
- Department of Biology, Carleton University, Ottawa, Ontario, Canada.
| |
Collapse
|
5
|
Högberg J, Järnberg J. Approaches for the setting of occupational exposure limits (OELs) for carcinogens. Crit Rev Toxicol 2023:1-37. [PMID: 37366107 DOI: 10.1080/10408444.2023.2218887] [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: 02/23/2023] [Revised: 05/12/2023] [Accepted: 05/22/2023] [Indexed: 06/28/2023]
Abstract
This article addresses issues of importance for occupational exposure limits (OELs) and chemical carcinogens with a focus on non-threshold carcinogens. It comprises scientific as well as regulatory issues. It is an overview, not a comprehensive review. A central topic is mechanistic research and insights, and its implications for cancer risk assessment. Alongside scientific advancements, the approaches of hazard identification and qualitative and quantitative risk assessment have developed over the years. The key steps in a quantitative risk assessment are outlined, with special attention given to the dose-response assessment and the derivation of an OEL using risk calculations or default assessment factors. The work procedures of several bodies performing cancer hazard identifications and quantitative risk assessments, as well as regulatory procedures to derive OELs for non-threshold carcinogens, are presented. Non-threshold carcinogens for which the European Union (EU) introduced binding OELs in 2017-2019 serve as illustrations together with some currently used strategies in the EU and elsewhere. Available knowledge supports the derivation of health-based OELs (Hb-OELs) for non-threshold carcinogens, and the use of a risk-based approach with low-dose linear extrapolation (linear non-threshold, LNT) as the default for non-threshold carcinogens. However, there is a need to develop methods that allow recent years' advances in cancer research to be used for improving risk estimates. It is recommended that defined risk levels (terminology and numerical values) are harmonised, and that both collective and individual risks are considered and clearly communicated. Socioeconomic aspects should be dealt with transparently and separated from the scientific health risk assessment.
Collapse
Affiliation(s)
- Johan Högberg
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | | |
Collapse
|
6
|
Smith-Roe SL, Hobbs CA, Hull V, Auman JT, Recio L, Streicker MA, Rivas MV, Pratt GA, Lo FY, Higgins JE, Schmidt EK, Williams LN, Nachmanson D, Valentine CC, Salk JJ, Witt KL. Adopting Duplex Sequencing™ Technology for Genetic Toxicity Testing: A Proof-of-Concept Mutagenesis Experiment with N-Ethyl-N-Nitrosourea (ENU)-Exposed Rats. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.08.539833. [PMID: 37214853 PMCID: PMC10197591 DOI: 10.1101/2023.05.08.539833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Duplex sequencing (DuplexSeq) is an error-corrected next-generation sequencing (ecNGS) method in which molecular barcodes informatically link PCR-copies back to their source DNA strands, enabling computational removal of errors by comparing grouped strand sequencing reads. The resulting background of less than one artifactual mutation per 10 7 nucleotides allows for direct detection of somatic mutations. TwinStrand Biosciences, Inc. has developed a DuplexSeq-based mutagenesis assay to sample the rat genome, which can be applied to genetic toxicity testing. To evaluate this assay for early detection of mutagenesis, a time-course study was conducted using male Hsd:Sprague Dawley SD rats (3 per group) administered a single dose of 40 mg/kg N-ethyl-N-nitrosourea (ENU) via gavage, with mutation frequency (MF) and spectrum analyzed in stomach, bone marrow, blood, and liver tissues at 3 h, 24 h, 7 d, and 28 d post-exposure. Significant increases in MF were observed in ENU-exposed rats as early as 24 h for stomach (site of contact) and bone marrow (a highly proliferative tissue) and at 7 d for liver and blood. The canonical, mutational signature of ENU was established by 7 d post-exposure in all four tissues. Interlaboratory analysis of a subset of samples from different tissues and time points demonstrated remarkable reproducibility for both MF and spectrum. These results demonstrate that MF and spectrum can be evaluated successfully by directly sequencing targeted regions of DNA obtained from various tissues, a considerable advancement compared to currently used in vivo gene mutation assays. HIGHLIGHTS DuplexSeq is an ultra-accurate NGS technology that directly quantifies mutationsENU-dependent mutagenesis was detected 24 h post-exposure in proliferative tissuesMultiple tissues exhibited the canonical ENU mutation spectrum 7 d after exposureResults obtained with DuplexSeq were highly concordant between laboratoriesThe Rat-50 Mutagenesis Assay is promising for applications in genetic toxicology.
Collapse
Affiliation(s)
| | - Cheryl A. Hobbs
- Integrated Laboratory Systems, LLC (an Inotiv company), Research Triangle Park, NC
| | - Victoria Hull
- Integrated Laboratory Systems, LLC (an Inotiv company), Research Triangle Park, NC
| | - J. Todd Auman
- Integrated Laboratory Systems, LLC (an Inotiv company), Research Triangle Park, NC
| | - Leslie Recio
- Integrated Laboratory Systems, LLC (an Inotiv company), Research Triangle Park, NC
| | - Michael A. Streicker
- Integrated Laboratory Systems, LLC (an Inotiv company), Research Triangle Park, NC
| | - Miriam V. Rivas
- Integrated Laboratory Systems, LLC (an Inotiv company), Research Triangle Park, NC
| | | | | | | | | | | | | | | | | | - Kristine L. Witt
- Division of Translational Toxicology, NIEHS, Research Triangle Park, NC
| |
Collapse
|
7
|
Blum K, FitzGerald R, Wilks MF, Barle EL, Hopf NB. Use of the benchmark-dose (BMD) approach to derive occupational exposure limits (OELs) for genotoxic carcinogens: N-nitrosamines. J Appl Toxicol 2023. [PMID: 36840679 DOI: 10.1002/jat.4455] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/29/2023] [Accepted: 02/21/2023] [Indexed: 02/26/2023]
Abstract
N-Nitrosamines are potent carcinogens and considered non-threshold carcinogens in various regulatory domains. However, recent data indicate the existence of a threshold for genotoxicity, which can be adequately demonstrated. This aspect has a critical impact on selecting the methodology that is applied to derive occupational exposure limits (OELs). OELs are used to protect workers potentially exposed to various chemicals by supporting the selection of appropriate control measures and ultimately reducing the risk of occupational cancer. Occupational exposures to nitrosamines occur during manufacturing processes, mainly in the rubber and chemical industry. The present study derives OELs for inhaled N-nitrosamines, employing the benchmark dose (BMD) approach if data are adequate and read-across for nitrosamines without adequate data. Additionally, benchmark dose lower confidence limit (BMDL) is preferred and more suitable point-of-departure (PoD) to calculate human health guidance values, including OEL. The lowest OEL (0.2 μg/m3 ) was derived for nitrosodiethylamine (NDEA), and nitrosopiperidine (NPIP) (OEL = 0.2 μg/m3 ), followed by nitrosopyrrolidine (NPYR) (0.4 μg/m3 ), nitrosodimethylamine (NDMA), nitrosodimethylamine (NMEA), and nitrosodipropylamine (NDPA) (0.5 μg/m3 ), nitrosomorpholine (NMOR) (OEL = 1 μg/m3 ), and nitrosodibutylamine (NDBA) (OEL = 2.5 μg/m3 ). Limits based on "non-threshold" TD50 slope calculation were within a 10-fold range. These proposed OELs do not consider skin absorption of nitrosamines, which is also a possible route of entry into the body, nor oral or other environmental sources. Furthermore, we recommend setting a limit for total nitrosamines based on the occupational exposure scenario and potency of components.
Collapse
Affiliation(s)
- Kamila Blum
- Environment, Health & Safety Department, GlaxoSmithKline, Munich, Germany.,Faculty of Science and Medicine, University of Geneva, Switzerland
| | - Rex FitzGerald
- Swiss Centre for Applied Human Toxicology (SCAHT) & Department of Pharmaceutical Sciences, University of Basel, Switzerland
| | - Martin F Wilks
- Swiss Centre for Applied Human Toxicology (SCAHT) & Department of Pharmaceutical Sciences, University of Basel, Switzerland
| | | | - Nancy B Hopf
- Swiss Centre for Applied Human Toxicology (SCAHT) & Department of Pharmaceutical Sciences, University of Basel, Switzerland.,Department for Occupational and Environmental Health, Centre for Primary Care and Public Health (Unisanté), University of Lausanne, Lausanne, Switzerland
| |
Collapse
|
8
|
In vitro genotoxic and antigenotoxic effects of an exopolysaccharide isolated from Lactobacillus salivarius KC27L. Toxicol In Vitro 2022; 86:105507. [DOI: 10.1016/j.tiv.2022.105507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 10/21/2022] [Accepted: 10/30/2022] [Indexed: 11/06/2022]
|
9
|
Lynch HN, Kozal JS, Russell AJ, Thompson WJ, Divis HR, Freid RD, Calabrese EJ, Mundt KA. Systematic review of the scientific evidence on ethylene oxide as a human carcinogen. Chem Biol Interact 2022; 364:110031. [PMID: 35779612 DOI: 10.1016/j.cbi.2022.110031] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/16/2022] [Accepted: 06/24/2022] [Indexed: 11/25/2022]
Abstract
Ethylene oxide is a highly reactive chemical primarily used as an intermediate in chemical production and as a sterilant of medical equipment and food products; it also is produced endogenously as a result of physiological processes. We conducted a systematic review of the potential carcinogenicity of inhaled ethylene oxide in humans using methods that adhere to PRIMSA guidelines and that incorporate aspects from the Institute of Medicine (IOM) (now the National Academy of Medicine) as well as several US Environmental Protection Agency (EPA) frameworks for systematic reviews. After a comprehensive literature search and selection process, study quality was evaluated following a method adapted from the EPA Toxic Substances Control Act (TSCA) framework. The literature screening and selection process identified 24 primary studies in animals or humans and more than 50 mechanistic studies. Integrating epidemiological, animal, and mechanistic literature on ethylene oxide and cancer according to the IOM framework yielded classifications of suggestive evidence of no association between ethylene oxide and stomach cancer, breast cancer and lymphohematopoietic malignancies at human relevant exposures. However, we acknowledge that there is additional uncertainty in the classification for lymphohematopoietic malignancies owing to a paucity of evidence for specific types of these tumors, each of which is a distinct disease entity of possibly unique etiology.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Kenneth A Mundt
- Cardno ChemRisk, Boston, MA, USA; University of Massachusetts, Amherst, MA, USA
| |
Collapse
|
10
|
Developing Structure-Activity Relationships for N-Nitrosamine Activity. COMPUTATIONAL TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2021; 20. [PMID: 34901581 DOI: 10.1016/j.comtox.2021.100186] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The detection of N-nitrosodimethylamine (NDMA) in several marketed drugs led regulatory agencies to require that N-nitrosamine risk assessments be performed on all marketed medical products [EMA/351053/2019 rev 1 (2019)]. Regulation of N-nitrosamine impurity levels in pharmaceutical drug substances and products is described in the ICH M7(R1) guideline where they are referred to as "cohort-of-concern" compounds as several are potent rodent carcinogens [Kroes et. al. 2004]. EMA, U.S. FDA and other regulatory agencies have set provisional acceptable daily intake limits for N-nitrosamines calculated from rodent carcinogenicity TD50 values for experimentally measured N-nitrosamines or the measured TD50 values of close analogs. The class-specific limit can be adjusted based upon a structure activity relationship analysis (SAR) and comparison with analogs having established carcinogenicity data [EMA/369136/2020, (2020)]. To investigate whether improvements in SARs can more accurately predict N-nitrosamine carcinogenic potency, an ad hoc workgroup of 23 companies and universities was established with the goals of addressing several scientific and regulatory issues including: reporting and review of N-nitrosamine mutagenicity and carcinogenicity reaction mechanisms, collection and review of available, public relevant experimental data, development of structure-activity relationships consistent with mechanisms for prediction of N-nitrosamine carcinogenic potency categories, and improved methods for calculating acceptable intake limits for N-nitrosamines based upon mechanistic analogs. Here we describe this collaboration and review our progress to date towards development of mechanistically based structure-activity relationships. We propose improving risk assessment of N-nitrosamines by first establishing the dominant reaction mechanism prior to retrieving an appropriate set of close analogs for use in read-across exercises.
Collapse
|
11
|
Johnson GE, Dobo K, Gollapudi B, Harvey J, Kenny J, Kenyon M, Lynch A, Minocherhomji S, Nicolette J, Thybaud V, Wheeldon R, Zeller A. Permitted daily exposure limits for noteworthy N-nitrosamines. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2021; 62:293-305. [PMID: 34089278 DOI: 10.1002/em.22446] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 05/07/2021] [Accepted: 05/11/2021] [Indexed: 06/12/2023]
Abstract
A genotoxic carcinogen, N-nitrosodimethylamine (NDMA), was detected as a synthesis impurity in some valsartan drugs in 2018, and other N-nitrosamines, such as N-nitrosodiethylamine (NDEA), were later detected in other sartan products. N-nitrosamines are pro-mutagens that can react with DNA following metabolism to produce DNA adducts, such as O6 -alkyl-guanine. The adducts can result in DNA replication miscoding errors leading to GC>AT mutations and increased risk of genomic instability and carcinogenesis. Both NDMA and NDEA are known rodent carcinogens in male and female rats. The DNA repair enzyme, methylguanine DNA-methyltransferase can restore DNA integrity via the removal of alkyl groups from guanine in an error-free fashion and this can result in nonlinear dose responses and a point of departure or "practical threshold" for mutation at low doses of exposure. Following International recommendations (ICHM7; ICHQ3C and ICHQ3D), we calculated permissible daily exposures (PDE) for NDMA and NDEA using published rodent cancer bioassay and in vivo mutagenicity data to determine benchmark dose values and define points of departure and adjusted with appropriate uncertainty factors (UFs). PDEs for NDMA were 6.2 and 0.6 μg/person/day for cancer and mutation, respectively, and for NDEA, 2.2 and 0.04 μg/person/day. Both PDEs are higher than the acceptable daily intake values (96 ng for NDMA and 26.5 ng for NDEA) calculated by regulatory authorities using simple linear extrapolation from carcinogenicity data. These PDE calculations using a bench-mark approach provide a more robust assessment of exposure limits compared with simple linear extrapolations and can better inform risk to patients exposed to the contaminated sartans.
Collapse
Affiliation(s)
- George E Johnson
- Swansea University Medical School, Swansea University, Swansea, Wales, UK
| | - Krista Dobo
- Genetic Toxicology, Drug Safety Research and Development, Pfizer, Groton, Connecticut, USA
| | - Bhaskar Gollapudi
- Center for Toxicology and Mechanistic Biology, Exponent Consulting, Midland, Michigan, USA
| | | | | | - Michelle Kenyon
- Genetic Toxicology, Drug Safety Research and Development, Pfizer, Groton, Connecticut, USA
| | | | | | - John Nicolette
- Genetic, Environmental and Occupational Toxicology, AbbVie, Chicago, Illinois, USA
| | | | - Ryan Wheeldon
- Swansea University Medical School, Swansea University, Swansea, Wales, UK
| | - Andreas Zeller
- Pharmaceutical Sciences, pRED Innovation Center Basel, Hoffmann-La Roche Ltd, Basel, Switzerland
| |
Collapse
|
12
|
Nicolette J, Murray J, Sonders P, Kondratiuk A, Crosby M. In vitro and in vivo mammalian mutation assays support a nonmutagenic mechanism of carcinogenicity for hydrazine. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2021; 62:4-17. [PMID: 32951273 DOI: 10.1002/em.22406] [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: 06/08/2020] [Revised: 08/13/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
Hydrazine has been described as a mutagenic, probable human carcinogen. It is mutagenic in in vitro systems such as bacterial reverse mutation (Ames) tests and some yeast systems, as well as in in vivo systems with drosophila. It was shown to cause chromosome damage both in vitro and in vivo but was negative in some well-validated mammalian mutation systems such as CHO HPRT assays. Importantly, there is only one in vivo gene mutation test reported, which was negative. Our objective was to determine if hydrazine is mutagenic in mammalian test systems. Thus, we conducted an in vitro gene mutation test in Muta™Mouse lung epithelial cells (FE1 cell assay) and a regulatory-compliant in vivo Big Blue® mouse test. Consistent with previous reports, an additional six-well Ames assay showed that hydrazine was mutagenic to bacteria. The FE1 cell assay was negative in conditions with and without metabolic activation when tested to cytotoxicity limits. In the Big Blue® mouse study, female mice received dosages of hydrazine up to 10.9 mg/kg via drinking water for 28 days. This dose is comparable to a dose used in a carcinogenicity study where female mice had significant increases in hepatocellular adenoma at 11.5 mg/kg. There were no increases in mutant frequency in liver and lung, two tissues sensitive to the carcinogenic effects of hydrazine in mice. Our research shows that hydrazine is not mutagenic in mammalian cells either in vitro or in vivo, indicating mutagenicity may not play a role in the carcinogenicity of hydrazine.
Collapse
Affiliation(s)
- John Nicolette
- Pre-Clinical Safety, AbbVie, Inc, North Chicago, Illinois, USA
| | - Joel Murray
- Pre-Clinical Safety, AbbVie, Inc, North Chicago, Illinois, USA
| | - Paul Sonders
- Pre-Clinical Safety, AbbVie, Inc, North Chicago, Illinois, USA
| | | | - Meredith Crosby
- Pre-Clinical Safety, AbbVie, Inc, North Chicago, Illinois, USA
| |
Collapse
|
13
|
Abstract
![]()
The cellular outcomes of chemical
exposure are as much about the
cellular response to the chemical as it is an effect of the chemical. We are growing in our understanding
of the genotoxic interaction between chemistry and biology. For example,
recent data has revealed the biological basis for mutation induction
curves for a methylating chemical, which has been shown to be dependent
on the repair capacity of the cells. However, this is just one end
point in the toxicity pathway from chemical exposure to cell death.
Much remains to be known in order for us to predict how cells will
respond to a certain dose. Methylating agents, a subset of alkylating
agents, are of particular interest, because of the variety of adverse
genetic end points that can result, not only at increasing doses,
but also over time. For instance, methylating agents are mutagenic,
their potency, for this end point, is determined by the cellular repair
capacity of an enzyme called methylguanine DNA-methyltransferase (MGMT)
and its ability to repair the induceed methyl adducts. However, methyl
adducts can become clastogenic. Erroneous biological processing will
convert mutagenic adducts to clastogenic events in the form of double
strand breaks (DSBs). How the cell responds to DSBs is via a cascade
of protein kinases, which is called the DNA damage response (DDR),
which will determine if the damage is repaired effectively, via homologous
recombination, or with errors, via nonhomologous end joining, or whether
the cell dies via apoptosis or enters senescence. The fate of cells
may be determined by the extent of damage and the resulting strength
of DDR signaling. Therefore, thresholds of damage may exist that determine
cell fate. Such thresholds would be dependent on each of the repair
and response mechanisms that these methyl adducts stimulate. The molecular
mechanism of how methyl adducts kill cells is still to be fully resolved.
If we are able to quantify each of these thresholds of damage for
a given cell, then we can ascertain, of the many adducts that are
induced, what proportion of them are mutagenic, what proportion are
clastogenic, and how many of these clastogenic events are toxic. This
review examines the possibility of dose and damage thresholds for
methylating agents, from the perspective of the underlying evolutionary
mechanisms that may be accountable.
Collapse
Affiliation(s)
- Adam D Thomas
- Centre for Research in Biosciences, University of the West of England, Frenchay Campus, Bristol BS16 1QY, United Kingdom
| |
Collapse
|
14
|
You X, Thiruppathi S, Liu W, Cao Y, Naito M, Furihata C, Honma M, Luan Y, Suzuki T. Detection of genome-wide low-frequency mutations with Paired-End and Complementary Consensus Sequencing (PECC-Seq) revealed end-repair-derived artifacts as residual errors. Arch Toxicol 2020; 94:3475-3485. [PMID: 32737516 DOI: 10.1007/s00204-020-02832-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 06/24/2020] [Indexed: 02/06/2023]
Abstract
To improve the accuracy and the cost-efficiency of next-generation sequencing in ultralow-frequency mutation detection, we developed the Paired-End and Complementary Consensus Sequencing (PECC-Seq), a PCR-free duplex consensus sequencing approach. PECC-Seq employed shear points as endogenous barcodes to identify consensus sequences from the overlap in the shortened, complementary DNA strand-derived paired-end reads for sequencing error correction. With the high accuracy of PECC-Seq, we identified the characteristic base substitution errors introduced by the end-repair process of mechanical fragmentation-based library preparations, which were prominent at the terminal 7 bp of the library fragments in the 5'-NpCpA-3' and 5'-NpCpT-3' trinucleotide context. As demonstrated at the human genome scale (TK6 cells), after removing these potential end-repair artifacts from the terminal 7 bp, PECC-Seq could reduce the sequencing error frequency to mid-10-7 with a relatively low sequencing depth. For TA base pairs, the background error rate could be suppressed to mid-10-8. In mutagen-treated (6 μg/mL methyl methanesulfonate or 12 μg/mL N-nitroso-N-ethylurea) TK6, increases in mutagen treatment-related mutant frequencies could be detected, indicating the potential of PECC-Seq in detecting genome-wide ultra-rare mutations. In addition, our finding on the patterns of end-repair artifacts may provide new insights into further reducing technical errors not only for PECC-Seq, but also for other next-generation sequencing techniques.
Collapse
Affiliation(s)
- Xinyue You
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, 227 South Chongqing Road, Shanghai, 200025, China.,Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki, 210-9501, Japan
| | - Suresh Thiruppathi
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki, 210-9501, Japan
| | - Weiying Liu
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, 227 South Chongqing Road, Shanghai, 200025, China
| | - Yiyi Cao
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, 227 South Chongqing Road, Shanghai, 200025, China.,Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki, 210-9501, Japan
| | - Mikihiko Naito
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki, 210-9501, Japan
| | - Chie Furihata
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki, 210-9501, Japan
| | - Masamitsu Honma
- Division of Genetics and Mutagenesis, National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki, 210-9501, Japan
| | - Yang Luan
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, 227 South Chongqing Road, Shanghai, 200025, China.
| | - Takayoshi Suzuki
- Division of Molecular Target and Gene Therapy Products, National Institute of Health Sciences, 3-25-26, Tonomachi, Kawasaki, 210-9501, Japan.
| |
Collapse
|
15
|
A systematic review on the genotoxic effect of serotonin and norepinephrine reuptake inhibitors (SNRIs) antidepressants. Psychopharmacology (Berl) 2020; 237:1909-1915. [PMID: 32529266 DOI: 10.1007/s00213-020-05550-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 05/11/2020] [Indexed: 12/12/2022]
Abstract
RATIONALE Depression is a major mental disorder affecting millions of people worldwide. Serotonin and norepinephrine reuptake inhibitors (SNRIs) are one of the antidepressant drugs prescribed for depression treatment. OBJECTIVE AND METHOD There are many contradiction studies about the adverse effect and genotoxicity of SNRIs. So here, based on the guidelines proposed at the PRISMA statement, we performed a quantitative systematic review by searching international electronic databases (PubMed, Scopus, Embase, and Web of Science) for published documents on SSNRIs and their genotoxicity effects. RESULTS The database searches retrieved 336 records, 18 of which met the inclusion criteria. Evaluation of the selected articles showed that a total of 9 articles were appropriate for final review. Most of these studies (78%) reported positive results for the genotoxicity of SNRIs CONCLUSION: Finally, we can conclude that these drugs have the potential to damage DNA.
Collapse
|
16
|
Hartwig A, Arand M, Epe B, Guth S, Jahnke G, Lampen A, Martus HJ, Monien B, Rietjens IMCM, Schmitz-Spanke S, Schriever-Schwemmer G, Steinberg P, Eisenbrand G. Mode of action-based risk assessment of genotoxic carcinogens. Arch Toxicol 2020; 94:1787-1877. [PMID: 32542409 PMCID: PMC7303094 DOI: 10.1007/s00204-020-02733-2] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 03/31/2020] [Indexed: 12/16/2022]
Abstract
The risk assessment of chemical carcinogens is one major task in toxicology. Even though exposure has been mitigated effectively during the last decades, low levels of carcinogenic substances in food and at the workplace are still present and often not completely avoidable. The distinction between genotoxic and non-genotoxic carcinogens has traditionally been regarded as particularly relevant for risk assessment, with the assumption of the existence of no-effect concentrations (threshold levels) in case of the latter group. In contrast, genotoxic carcinogens, their metabolic precursors and DNA reactive metabolites are considered to represent risk factors at all concentrations since even one or a few DNA lesions may in principle result in mutations and, thus, increase tumour risk. Within the current document, an updated risk evaluation for genotoxic carcinogens is proposed, based on mechanistic knowledge regarding the substance (group) under investigation, and taking into account recent improvements in analytical techniques used to quantify DNA lesions and mutations as well as "omics" approaches. Furthermore, wherever possible and appropriate, special attention is given to the integration of background levels of the same or comparable DNA lesions. Within part A, fundamental considerations highlight the terms hazard and risk with respect to DNA reactivity of genotoxic agents, as compared to non-genotoxic agents. Also, current methodologies used in genetic toxicology as well as in dosimetry of exposure are described. Special focus is given on the elucidation of modes of action (MOA) and on the relation between DNA damage and cancer risk. Part B addresses specific examples of genotoxic carcinogens, including those humans are exposed to exogenously and endogenously, such as formaldehyde, acetaldehyde and the corresponding alcohols as well as some alkylating agents, ethylene oxide, and acrylamide, but also examples resulting from exogenous sources like aflatoxin B1, allylalkoxybenzenes, 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx), benzo[a]pyrene and pyrrolizidine alkaloids. Additionally, special attention is given to some carcinogenic metal compounds, which are considered indirect genotoxins, by accelerating mutagenicity via interactions with the cellular response to DNA damage even at low exposure conditions. Part C finally encompasses conclusions and perspectives, suggesting a refined strategy for the assessment of the carcinogenic risk associated with an exposure to genotoxic compounds and addressing research needs.
Collapse
Affiliation(s)
- Andrea Hartwig
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany.
| | - Michael Arand
- Institute of Pharmacology and Toxicology, University of Zurich, 8057, Zurich, Switzerland
| | - Bernd Epe
- Institute of Pharmacy and Biochemistry, University of Mainz, 55099, Mainz, Germany
| | - Sabine Guth
- Department of Toxicology, IfADo-Leibniz Research Centre for Working Environment and Human Factors, TU Dortmund, Ardeystr. 67, 44139, Dortmund, Germany
| | - Gunnar Jahnke
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Alfonso Lampen
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Hans-Jörg Martus
- Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Bernhard Monien
- Department of Food Safety, German Federal Institute for Risk Assessment (BfR), 10589, Berlin, Germany
| | - Ivonne M C M Rietjens
- Division of Toxicology, Wageningen University, Stippeneng 4, 6708 WE, Wageningen, The Netherlands
| | - Simone Schmitz-Spanke
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, University of Erlangen-Nuremberg, Henkestr. 9-11, 91054, Erlangen, Germany
| | - Gerlinde Schriever-Schwemmer
- Department of Food Chemistry and Toxicology, Institute of Applied Biosciences (IAB), Karlsruhe Institute of Technology (KIT), Adenauerring 20a, 76131, Karlsruhe, Germany
| | - Pablo Steinberg
- Max Rubner-Institut, Federal Research Institute of Nutrition and Food, Haid-und-Neu-Str. 9, 76131, Karlsruhe, Germany
| | - Gerhard Eisenbrand
- Retired Senior Professor for Food Chemistry and Toxicology, Kühler Grund 48/1, 69126, Heidelberg, Germany.
| |
Collapse
|
17
|
White PA, Long AS, Johnson GE. Quantitative Interpretation of Genetic Toxicity Dose-Response Data for Risk Assessment and Regulatory Decision-Making: Current Status and Emerging Priorities. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:66-83. [PMID: 31794061 DOI: 10.1002/em.22351] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 11/27/2019] [Accepted: 11/30/2019] [Indexed: 06/10/2023]
Abstract
The screen-and-bin approach for interpretation of genotoxicity data is predicated on three false assumptions: that genotoxicants are rare, that genotoxicity dose-response functions do not contain a low-dose region mechanistically characterized by zero-order kinetics, and that genotoxicity is not a bona fide toxicological endpoint. Consequently, there is a need to develop and implement quantitative methods to interpret genotoxicity dose-response data for risk assessment and regulatory decision-making. Standardized methods to analyze dose-response data, and determine point-of-departure (PoD) metrics, have been established; the most robust PoD is the benchmark dose (BMD). However, there are no standards for regulatory interpretation of mutagenicity BMDs. Although 5-10% is often used as a critical effect size (CES) for BMD determination, values for genotoxicity endpoints have not been established. The use of BMDs to determine health-based guidance values (HBGVs) requires assessment factors (AFs) to account for interspecies differences and variability in human sensitivity. Default AFs used for other endpoints may not be appropriate for interpretation of in vivo mutagenicity BMDs. Analyses of published dose-response data showing the effects of compensatory pathway deficiency indicate that AFs for sensitivity differences should be in the range of 2-20. Additional analyses indicate that the AF to compensate for short treatment durations should be in the range of 5-15. Future work should use available data to empirically determine endpoint-specific CES values; similarly, to determine AF values for BMD adjustment. Future work should also evaluate the ability to use in vitro dose-response data for risk assessment, and the utility of probabilistic methods for determination of mutagenicity HBGVs. Environ. Mol. Mutagen. 61:66-83, 2020. © 2019 Her Majesty the Queen in Right of Canada.
Collapse
Affiliation(s)
- Paul A White
- Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, Canada
| | - Alexandra S Long
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - George E Johnson
- Swansea University Medical School, Swansea, Wales, United Kingdom
| |
Collapse
|
18
|
Smart DJ, Helbling FR, Verardo M, Huber A, McHugh D, Vanscheeuwijck P. Development of an integrated assay in human TK6 cells to permit comprehensive genotoxicity analysis in vitro. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2020; 849:503129. [DOI: 10.1016/j.mrgentox.2019.503129] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 11/26/2019] [Accepted: 12/23/2019] [Indexed: 01/24/2023]
|
19
|
Genome-wide somatic mutation analysis via Hawk-Seq™ reveals mutation profiles associated with chemical mutagens. Arch Toxicol 2019; 93:2689-2701. [PMID: 31451845 DOI: 10.1007/s00204-019-02541-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 08/14/2019] [Indexed: 12/25/2022]
Abstract
It is difficult to identify mutagen-induced genome-wide somatic mutations using next generation sequencing; hence, mutagenic features of each mutagen and their roles in cancer development require further elucidation. We described Hawk-Seq™, a highly accurate genome sequencing method and the optimal conditions, for using it to construct libraries that would enable the accurate (c.a. 1 error/107-108 bp) and efficient survey of genome-wide mutations. Genomic mutations in gpt delta mice or Salmonella typhimurium TA100 exposed to methylnitrosourea (MNU), ethylnitrosourea (ENU), diethylnitrosamine (DEN), benzo[a]pyrene (BP), and aristolochic acid (AA) were profiled using Hawk-Seq™ to analyse positions, substitution patterns, or frequencies. The resultant vast mutation data provided high-resolution mutational signatures, including for minor mutational fractions (e.g. G:C>A:T by AA), which enabled the clarification of the mutagenic features of all mutagens. The 96-type mutational signatures of MNU, AA, and BP indicate their partial similarity to signature 11, 22, and 4 or 29, respectively. Meanwhile, signatures attributable to ENU and DEN were highly similar to each other, but not to signature 11, suggesting that the mechanisms of these agents differed from those of typical alkylating agents. Thus, Hawk-Seq™ can clarify genome-wide chemical mutagenicity profiles at extraordinary resolutions, thereby providing insight into mutagen mechanisms and their roles in cancer development.
Collapse
|
20
|
Machado NM, Ribeiro AB, Nicolella HD, Ozelin SD, Silva LHDD, Guissone APP, Rinaldi-Neto F, Lemos ILL, Furtado RA, Cunha WR, Rezende AAAD, Spanó MA, Tavares DC. Usnic acid attenuates genomic instability in Chinese hamster ovary (CHO) cells as well as chemical-induced preneoplastic lesions in rat colon. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2019; 82:401-410. [PMID: 31066341 DOI: 10.1080/15287394.2019.1613274] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Usnic acid (UA) is one of the pharmacologically most important compounds produced by several lichen species. To better understand the mechanism of action (MOA) of this important substance, this study examined the genotoxicity attributed to UA and its influence on mutagens with varying MOA using the micronucleus (MN) test in Chinese hamster ovary cells (CHO). Additional experiments were conducted to investigate the effect of UA on colon carcinogenesis in Wistar rats employing the aberrant crypt focus (ACF) assay. In vitro studies showed a significant increase in the frequency of MN in cultures treated with the highest UA concentration tested (87.13 µM). In contrast, UA concentrations of 10.89, 21.78, or 43.56 µM produced an approximate 60% reduction in chromosomal damage induced by doxorubicin, hydrogen peroxide, and etoposide, indicating an antigenotoxic effect. In the ACF assay, male Wistar rats treated with different UA doses (3.125, 12.5, or 50 mg/kg b.w.) and with the carcinogen 1,2-dimethylhydrazine exhibited a significantly lower incidence of neoplastic lesions in the colon than animals treated only with the carcinogen. Data suggest that the MOA responsible for the chemopreventive effect of UA may be related to interaction with DNA topoisomerase II and/or the antioxidant potential of the compound.
Collapse
Affiliation(s)
- Nayane Moreira Machado
- a Institute of Biotechnology , Federal University of Uberlândia , Uberlândia , MG , Brazil
| | | | | | | | | | | | | | | | | | | | - Alexandre Azenha Alves De Rezende
- a Institute of Biotechnology , Federal University of Uberlândia , Uberlândia , MG , Brazil
- c Faculty of Integrated Sciences of Pontal , Federal University of Uberlândia , Ituiutaba , MG , Brazil
| | - Mário Antônio Spanó
- a Institute of Biotechnology , Federal University of Uberlândia , Uberlândia , MG , Brazil
| | | |
Collapse
|
21
|
Kucab JE, Zou X, Morganella S, Joel M, Nanda AS, Nagy E, Gomez C, Degasperi A, Harris R, Jackson SP, Arlt VM, Phillips DH, Nik-Zainal S. A Compendium of Mutational Signatures of Environmental Agents. Cell 2019; 177:821-836.e16. [PMID: 30982602 PMCID: PMC6506336 DOI: 10.1016/j.cell.2019.03.001] [Citation(s) in RCA: 341] [Impact Index Per Article: 68.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/21/2018] [Accepted: 02/28/2019] [Indexed: 12/21/2022]
Abstract
Whole-genome-sequencing (WGS) of human tumors has revealed distinct mutation patterns that hint at the causative origins of cancer. We examined mutational signatures in 324 WGS human-induced pluripotent stem cells exposed to 79 known or suspected environmental carcinogens. Forty-one yielded characteristic substitution mutational signatures. Some were similar to signatures found in human tumors. Additionally, six agents produced double-substitution signatures and eight produced indel signatures. Investigating mutation asymmetries across genome topography revealed fully functional mismatch and transcription-coupled repair pathways. DNA damage induced by environmental mutagens can be resolved by disparate repair and/or replicative pathways, resulting in an assortment of signature outcomes even for a single agent. This compendium of experimentally induced mutational signatures permits further exploration of roles of environmental agents in cancer etiology and underscores how human stem cell DNA is directly vulnerable to environmental agents. VIDEO ABSTRACT.
Collapse
Affiliation(s)
- Jill E Kucab
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, UK
| | - Xueqing Zou
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge CB2 9NB, UK; MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK; Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK
| | | | - Madeleine Joel
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, UK
| | - A Scott Nanda
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge CB2 9NB, UK
| | - Eszter Nagy
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, UK
| | - Celine Gomez
- Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK
| | - Andrea Degasperi
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge CB2 9NB, UK; MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK; Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK
| | - Rebecca Harris
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge CB2 9NB, UK; Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK
| | - Stephen P Jackson
- The Gurdon Institute, University of Cambridge, Cambridge CB2 1QN, UK
| | - Volker M Arlt
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, UK
| | - David H Phillips
- Department of Analytical, Environmental and Forensic Sciences, MRC-PHE Centre for Environment and Health, King's College London, 150 Stamford Street, London SE1 9NH, UK.
| | - Serena Nik-Zainal
- Academic Department of Medical Genetics, School of Clinical Medicine, University of Cambridge, Cambridge CB2 9NB, UK; MRC Cancer Unit, University of Cambridge, Cambridge CB2 0XZ, UK; Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
| |
Collapse
|
22
|
Pottenger LH, Boysen G, Brown K, Cadet J, Fuchs RP, Johnson GE, Swenberg JA. Understanding the importance of low-molecular weight (ethylene oxide- and propylene oxide-induced) DNA adducts and mutations in risk assessment: Insights from 15 years of research and collaborative discussions. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2019; 60:100-121. [PMID: 30536466 PMCID: PMC6590209 DOI: 10.1002/em.22248] [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: 03/30/2018] [Revised: 08/10/2018] [Accepted: 08/23/2018] [Indexed: 05/11/2023]
Abstract
The interpretation and significance of DNA adduct data, their causal relationship to mutations, and their role in risk assessment have been debated for many years. An extended effort to identify key questions and collect relevant data to address them was focused on the ubiquitous low MW N7-alkyl/hydroxyalkylguanine adducts. Several academic, governmental, and industrial laboratories collaborated to gather new data aimed at better understanding the role and potential impact of these adducts in quantifiable genotoxic events (gene mutations/micronucleus). This review summarizes and evaluates the status of dose-response data for DNA adducts and mutations from recent experimental work with standard mutagenic agents and ethylene oxide and propylene oxide, and the importance for risk assessment. This body of evidence demonstrates that small N7-alkyl/hydroxyalkylguanine adducts are not pro-mutagenic and, therefore, adduct formation alone is not adequate evidence to support a mutagenic mode of action. Quantitative methods for dose-response analysis and derivation of thresholds, benchmark dose (BMD), or other points-of-departure (POD) for genotoxic events are now available. Integration of such analyses of genetox data is necessary to properly assess any role for DNA adducts in risk assessment. Regulatory acceptance and application of these insights remain key challenges that only the regulatory community can address by applying the many learnings from recent research. The necessary tools, such as BMDs and PODs, and the example datasets, are now available and sufficiently mature for use by the regulatory community. Environ. Mol. Mutagen. 60: 100-121, 2019. © 2018 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.
Collapse
Affiliation(s)
- L. H. Pottenger
- Olin Corporation/Blue Cube Operations, LLC, retired, LHP TOX CONSULT, LLCMidlandMIUSA
| | - G. Boysen
- Department of Environmental and Occupational Health and The Winthrop P Rockefeller Cancer Institute University of Arkansas for Medical SciencesLittle RockArkansasUSA
| | - K. Brown
- Leicester Cancer Research CentreUniversity of LeicesterLeicesterUnited Kingdom
| | - J. Cadet
- Institut Nanosciences et Cryogénie, CEA‐GrenobleGrenobleFrance
- Université de SherbrookeSherbrookeCanada
| | - R. P. Fuchs
- Centre de Recherche en Cancérologie de Marseille (CRCM), Inserm, U1068Marseille, 13009France
- CNRS, UMR7258Marseille, 13009France
- Institut Paoli‐CalmettesMarseille, 13009France
- Aix‐Marseille UniversityUM 105, 13284, MarseilleFrance
| | - G. E. Johnson
- Swansea University, Institute of Life SciencesSwanseaUnited Kingdom
| | - J. A. Swenberg
- University of North CarolinaChapel HillNorth CarolinaUSA
| |
Collapse
|
23
|
Gerić M, Gajski G, Domijan AM, Garaj-Vrhovac V, Filipič M, Žegura B. Genotoxic effects of neurotoxin ß-N-methylamino-l-alanine in human peripheral blood cells. CHEMOSPHERE 2019; 214:623-632. [PMID: 30290362 DOI: 10.1016/j.chemosphere.2018.09.155] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 09/21/2018] [Accepted: 09/26/2018] [Indexed: 06/08/2023]
Abstract
The non-proteinogenic amino acid ß-N-methylamino-l-alanine (BMAA) is associated with the development of neurodegenerative diseases such as Alzheimer's disease, amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS-PDC) and amyotrophic lateral sclerosis. BMAA is known to induce neurotoxic effects leading to neurodegeneration via multiple mechanisms including misfolded protein accumulation, glutamate induced excitotoxicity, calcium dyshomeostasis, endoplasmic reticulum stress and oxidative stress. In the present study, for the first time, genotoxic activity of BMAA (2.5, 5, 10 and 20 μg/mL) was studied in human peripheral blood cells (HPBCs) using the comet and cytokinesis-block micronucleus cytome assays. In addition, the influence of BMAA on the oxidative stress was assessed. At non-cytotoxic concentrations BMAA did not induce formation of DNA strand breaks in HPBCs after 4 and 24 h exposure; however, it significantly increased the number of micronuclei after 24 and 48 h at 20 μg/mL and nucleoplasmic bridges after 48 h at 20 μg/mL. The frequency of nuclear buds was slightly though non-significantly increased after 48 h. Altogether, this indicates that in HPBCs BMAA is clastogenic and induces complex genomic alterations including structural chromosomal rearrangements and gene amplification. No influence on oxidative stress markers was noticed. These findings provide new evidence that environmental neurotoxin BMAA, in addition to targeting common pathways involved in neurodegeneration, can also induce genomic instability in non-target HPBCs suggesting that it might be involved in cancer development. Therefore, these data are important in advancing our current knowledge and opening new questions in the understanding of the mechanisms of BMAA toxicity, particularly in the context of genotoxicity.
Collapse
Affiliation(s)
- Marko Gerić
- Mutagenesis Unit, Institute for Medical Research and Occupational Health, 10000 Zagreb, Croatia.
| | - Goran Gajski
- Mutagenesis Unit, Institute for Medical Research and Occupational Health, 10000 Zagreb, Croatia.
| | - Ana-Marija Domijan
- Department of Pharmaceutical Botany, Faculty of Pharmacy and Biochemistry, University of Zagreb, 10000 Zagreb, Croatia.
| | - Vera Garaj-Vrhovac
- Mutagenesis Unit, Institute for Medical Research and Occupational Health, 10000 Zagreb, Croatia.
| | - Metka Filipič
- Department for Genetic Toxicology and Cancer Biology, National Institute of Biology, 1000 Ljubljana, Slovenia.
| | - Bojana Žegura
- Department for Genetic Toxicology and Cancer Biology, National Institute of Biology, 1000 Ljubljana, Slovenia.
| |
Collapse
|
24
|
Metruccio F, Moretto A. Genotoxicity in risk assessment: is it time to use a threshold approach? CURRENT OPINION IN TOXICOLOGY 2018. [DOI: 10.1016/j.cotox.2018.11.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
25
|
Gurushankara HP, Venu R, Vasudev V. Hyperthermia enhances methyl methanesulfonate-induced adaptive response in meiotic cells of grasshopper Poecilocerus pictus. Mutagenesis 2018; 33:215-224. [PMID: 29986047 DOI: 10.1093/mutage/gey009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 05/06/2018] [Indexed: 11/13/2022] Open
Abstract
To understand the role of hyperthermia (HT) in adaptive response, methyl methanesulfonate (MMS) adapted meiotic cells of Poecilocerus pictus were used. Poecilocerus pictus were treated with conditioning (L) or challenging (H) dose of MMS and 2-h time lag (TL) between these doses (L-2h-H) (combined) was employed. Different treatment schedules were used to analyse the influence of HT on MMS-induced adaptive response namely pre; inter; post-treatment and cross-adaptation. After each treatment schedules, chromosomal anomalies were analysed. The frequencies of chromosomal anomalies induced by conditioning and challenging doses of MMS were significantly higher (P < 0.0001) compared to that of the control or HT groups. The combined treatments resulted in significant reduction of chromosomal anomalies compared to additive effect of MMS (P < 0.0001). The pre, inter, post and cross-adaptation treatments with HT reduced the frequencies of chromosomal anomalies compared to the challenge and combined treatments with MMS. There is a protection against MMS-induced chromosomal anomalies by HT in in vivo P.pictus. This is the first report to demonstrate that HT enhances the MMS-induced adaptive response in in vivo meiotic cells.
Collapse
Affiliation(s)
| | - Ramamurthy Venu
- Department of P.G. Studies and Research in Applied Zoology, Kuvempu University, Shankaraghatta, Shivamogga, Karnataka, India
| | - Venkateshaiah Vasudev
- Department of Zoology, Davanagere University, Shivagangothri, Davanagere, Karnataka, India
| |
Collapse
|
26
|
Ayabaktı S, Yavuz Kocaman A. Cytogenotoxic effects of venlafaxine hydrochloride on cultured human peripheral blood lymphocytes. Drug Chem Toxicol 2018; 43:192-199. [PMID: 30025480 DOI: 10.1080/01480545.2018.1486410] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The potential genotoxic effect of venlafaxine hydrochloride (venlafaxine), an antidepressant drug-active ingredient, was investigated by using in vitro chromosome aberrations (CAs) and cytokinesis-block micronucleus (CBMN) assays in human peripheral blood lymphocytes (PBLs). Mitotic index (MI) and cytokinesis-block proliferation index (CBPI) were also calculated to determine the cytotoxicity of this active drug. For this aim, the human PBLs were treated with 25, 50, and 100 µg/ml venlafaxine for 24 h and 48 h. The results of this study showed that venlafaxine significantly induced the formation of structural CA and MN for all concentrations (25, 50, and 100 µg/ml) and treatment periods (24 h and 48 h) when compared with the negative and the solvent control (except 25 µg/ml at 48 h for MN). In addition, the increases in the percentage of structural CA and MN were concentration-dependent for both treatment times. With regard to cell cycle kinetics, venlafaxine significantly decreased the MI at all concentrations, and also CBPI at the higher concentrations for both treatment times as compared to the control groups. The present results indicate for the first time that venlafaxine had significant clastogenic and cytotoxic effects at the tested concentrations (25, 50, and 100 µg/ml) in the human PBLs, in vitro; therefore, its excessive and careless use may pose a potential risk to human health.
Collapse
Affiliation(s)
- Selim Ayabaktı
- Basic and Applied Sciences Institute, Hatay Mustafa Kemal University, Hatay, Turkey
| | - Ayşe Yavuz Kocaman
- Department of Biology, Faculty of Sciences and Letters, Hatay Mustafa Kemal University, Hatay, Turkey
| |
Collapse
|
27
|
A genome-wide mutation analysis method enabling high-throughput identification of chemical mutagen signatures. Sci Rep 2018; 8:9583. [PMID: 29942026 PMCID: PMC6018237 DOI: 10.1038/s41598-018-27755-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 06/08/2018] [Indexed: 12/17/2022] Open
Abstract
Trinucleotide mutational signatures extracted from cancer genomes provide clues useful in understanding the roles of mutagens and mutagenic mechanisms in cancer development. The lack of a simple method for genome-wide analysis of alterations induced by mutagens hampers the identification of trinucleotide signatures of mutagen exposure and evaluation of their relationships with human cancers. Here, we describe a novel approach to facilitate analysis of chemically induced mutations in bacterial cells by detection of increased frequencies of base substitutions after mutagen exposure, using paired-end overlapping next-generation sequencing. DNA samples from Salmonella typhimurium strain TA100, exposed to three alkylating agents, ethylnitrosourea (ENU), methylnitrosourea (MNU), and ethyl methansulphonate (EMS), were analysed. The G:C > A:T mutation frequency was increased in all samples, whereas A:T base pair substitution frequencies were increased specifically in samples exposed to ENU, consistent with previous reports. Mutation patterns in the context of 96 possible trinucleotide formats in these samples exhibited a sharp peak corresponding to an NpCpY consensus sequence, which is similar to the mutational signature of alkylating agents in human cancer. These results indicate that our approach can be useful in facilitating the understanding of mechanisms underlying chemical mutagenicity and for identification of unknown causal mutagens in human cancer.
Collapse
|
28
|
Yonemura S, Doane S, Keil S, Goodrich R, Pidcoke H, Cardoso M. Improving the safety of whole blood-derived transfusion products with a riboflavin-based pathogen reduction technology. BLOOD TRANSFUSION = TRASFUSIONE DEL SANGUE 2017; 15:357-364. [PMID: 28665269 PMCID: PMC5490732 DOI: 10.2450/2017.0320-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 12/19/2016] [Indexed: 01/06/2023]
Abstract
Worldwide safety of blood has been positively impacted by technological, economic and social improvements; nevertheless, growing socio-political changes of contemporary society together with environmental changes challenge the practice of blood transfusion with a continuous source of unforeseeable threats with the emergence and re-emergence of blood-borne pathogens. Pathogen reduction (PR) is a proactive strategy to mitigate the risk of transfusion-transmitted infections. PR technologies for the treatment of single plasma units and platelet concentrates are commercially available and have been successfully implemented in more than 2 dozen countries worldwide. Ideally, all labile blood components should be PR treated to ensure a safe and sustainable blood supply in accordance with regional transfusion best practices. Recently, a device (Mirasol® Pathogen Reduction Technology System) for PR treatment of whole blood using riboflavin and UV light has received CE marking, a significant step forward in realising blood safety where WB transfusion is the norm, such as in sub-Saharan Africa and in far-forward combat situations. There is also keen interest in the ability to derive components from Mirasol®-treated whole blood, as it is seen as a more efficient and economical means to implement universal PR in the blood centre environment than treatment of components with different PR systems.
Collapse
Affiliation(s)
| | - Suzann Doane
- Terumo BCT, Lakewood, CO, United States of America
| | - Shawn Keil
- Terumo BCT, Lakewood, CO, United States of America
| | - Raymond Goodrich
- Terumo BCT, Lakewood, CO, United States of America
- Infectious Disease Research Center, Colorado State University, Fort Collins, CO, United States of America
| | | | | |
Collapse
|
29
|
Chen HH, Xu XL, Shang Y, Jiang JG. Comparative toxic effects of butylparaben sodium, sodium diacetate and potassium sorbate toDunaliella tertiolectaand HL7702 cells. Food Funct 2017; 8:4478-4486. [DOI: 10.1039/c7fo01102d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The aim of this study is to further evaluate the toxicities of Butylparaben sodium (BP), sodium diacetate (SDA) and potassium sorbate (PS) using microalgae cells, and a comparison is made with their mammalian cell cytotoxicities.
Collapse
Affiliation(s)
- Hao-Hong Chen
- College of Food Science and Technology
- South China University of Technology
- Guangzhou
- 510640
- China
| | - Xi-Lin Xu
- College of Food Science and Technology
- South China University of Technology
- Guangzhou
- 510640
- China
| | - Yu Shang
- College of Food Science and Technology
- South China University of Technology
- Guangzhou
- 510640
- China
| | - Jian-Guo Jiang
- College of Food Science and Technology
- South China University of Technology
- Guangzhou
- 510640
- China
| |
Collapse
|
30
|
Shah UK, Seager AL, Fowler P, Doak SH, Johnson GE, Scott SJ, Scott AD, Jenkins GJS. A comparison of the genotoxicity of benzo[a]pyrene in four cell lines with differing metabolic capacity. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2016; 808:8-19. [PMID: 27637481 DOI: 10.1016/j.mrgentox.2016.06.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 06/03/2016] [Accepted: 06/06/2016] [Indexed: 01/19/2023]
Abstract
Benzo[a]pyrene (B[a]P) is a known genotoxin and carcinogen, yet its genotoxic response at low level exposure has not been determined. This study was conducted to examine the interplay of dose and metabolic capacity on genotoxicity of B[a]P. Investigating and better understanding the biological significance of low level chemical exposures will help improve human health risk assessments. The genotoxic and mutagenic effects of B[a]P were investigated using human cell lines (AHH-1, MCL-5, TK6 and HepG2) with differential expression of the CYP450 enzymes CYP1A1, 1B1 and1A2 involved in B[a]P metabolism. MCL-5 and HepG2 cells showed detectable basal expression and activity of CYP1A1, 1B1 and 1A2 than AHH-1 which only show CYP1A1 basal expression and activity. TK6 cells showed negligible expression levels of all three CYP450 enzymes. In vitro micronucleus and HPRT assays were conducted to determine the effect of B[a]P on chromosome damage and point mutation induction. After 24h exposure, linear increases in micronucleus (MN) frequency were observed in all cell lines except TK6. After 4h exposure, only the metabolically competent cell lines MCL-5 and HepG2 showed MN induction (with a threshold concentration at 25.5μM from MCL-5 cells) indicating the importance of exposure time for genotoxicity. The HPRT assay also displayed linear increases in mutant frequency in MCL-5 cells, after 4h and 24h treatments. Mutation spectra analysis of MCL-5 and AHH-1 HPRT mutants revealed frequent B[a]P induced G to T transversion mutations (72% and 44% of induced mutations in MCL-5 and AHH-1 respectively). This study therefore demonstrates a key link between metabolic capability, B[a]P exposure time and genotoxicity.
Collapse
Affiliation(s)
- Ume-Kulsoom Shah
- Institute of Life Sciences, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Anna L Seager
- Institute of Life Sciences, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Paul Fowler
- Safety & Environmental Assurance Centre (SEAC), Unilever, Bedford, MK44 1LQ, UK
| | - Shareen H Doak
- Institute of Life Sciences, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - George E Johnson
- Institute of Life Sciences, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Sharon J Scott
- Safety & Environmental Assurance Centre (SEAC), Unilever, Bedford, MK44 1LQ, UK
| | - Andrew D Scott
- Safety & Environmental Assurance Centre (SEAC), Unilever, Bedford, MK44 1LQ, UK
| | - Gareth J S Jenkins
- Institute of Life Sciences, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK.
| |
Collapse
|
31
|
Avuloglu Yilmaz E, Unal F, Yuzbasioglu D. Evaluation of cytogenetic and DNA damage induced by the antidepressant drug-active ingredients, trazodone and milnacipran, in vitro. Drug Chem Toxicol 2016; 40:57-66. [DOI: 10.1080/01480545.2016.1174870] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
32
|
Brüsehafer K, Manshian BB, Doherty AT, Zaïr ZM, Johnson GE, Doak SH, Jenkins GJS. The clastogenicity of 4NQO is cell-type dependent and linked to cytotoxicity, length of exposure and p53 proficiency. Mutagenesis 2016; 31:171-80. [PMID: 26362870 PMCID: PMC4748179 DOI: 10.1093/mutage/gev069] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
4-Nitroquinoline 1-oxide (4NQO) is used as a positive control in various genotoxicity assays because of its known mutagenic and carcinogenic properties. The chemical is converted into 4-hydroxyaminoquinoline 1-oxide and gives rise to three main DNA adducts, N-(deoxyguanosin-8-yl)-4AQO, 3-(desoxyguanosin-N (2)-yl)-4AQO and 3-(deoxyadenosin-N (6)-yl)-4AQO. This study was designed to assess the shape of the dose-response curve at low concentrations of 4NQO in three human lymphoblastoid cell lines, MCL-5, AHH-1 and TK6 as well as the mouse lymphoma L5178Y cell line in vitro. Chromosomal damage was investigated using the in vitro micronucleus assay, while further gene mutation and DNA damage studies were carried out using the hypoxanthine-guanine phosphoribosyltransferase forward mutation and comet assays. 4NQO showed little to no significant increases in micronucleus induction in the human lymphoblastoid cell lines, even up to 55±5% toxicity. A dose-response relationship could only be observed in the mouse lymphoma cell line L5178Y after 4NQO treatment, even at concentrations with no reduction in cell viability. Further significant increases in gene mutation and DNA damage induction were observed. Hence, 4NQO is a more effective point mutagen than clastogen, and its suitability as a positive control for genotoxicity testing has to be evaluated for every individual assay.
Collapse
Affiliation(s)
- Katja Brüsehafer
- *To whom correspondence should be addressed. ILS1, College of Medicine, Swansea University, Singleton Park, Swansea SA2 8PP, UK. Tel: +44 179 260 2512; Fax: +44 179 260 2147;
| | | | - Ann T. Doherty
- Drug Safety and Metabolism, AstraZeneca, Unit 310, Darwin Building, Cambridge Science Park, Milton Road, Cambridge CB40WG, UK
| | | | | | | | | |
Collapse
|
33
|
Klapacz J, Pottenger LH, Engelward BP, Heinen CD, Johnson GE, Clewell RA, Carmichael PL, Adeleye Y, Andersen ME. Contributions of DNA repair and damage response pathways to the non-linear genotoxic responses of alkylating agents. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2015; 767:77-91. [PMID: 27036068 DOI: 10.1016/j.mrrev.2015.11.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/26/2015] [Accepted: 11/27/2015] [Indexed: 11/27/2022]
Abstract
From a risk assessment perspective, DNA-reactive agents are conventionally assumed to have genotoxic risks at all exposure levels, thus applying a linear extrapolation for low-dose responses. New approaches discussed here, including more diverse and sensitive methods for assessing DNA damage and DNA repair, strongly support the existence of measurable regions where genotoxic responses with increasing doses are insignificant relative to control. Model monofunctional alkylating agents have in vitro and in vivo datasets amenable to determination of points of departure (PoDs) for genotoxic effects. A session at the 2013 Society of Toxicology meeting provided an opportunity to survey the progress in understanding the biological basis of empirically-observed PoDs for DNA alkylating agents. Together with the literature published since, this review discusses cellular pathways activated by endogenous and exogenous alkylation DNA damage. Cells have evolved conserved processes that monitor and counteract a spontaneous steady-state level of DNA damage. The ubiquitous network of DNA repair pathways serves as the first line of defense for clearing of the DNA damage and preventing mutation. Other biological pathways discussed here that are activated by genotoxic stress include post-translational activation of cell cycle networks and transcriptional networks for apoptosis/cell death. The interactions of various DNA repair and DNA damage response pathways provide biological bases for the observed PoD behaviors seen with genotoxic compounds. Thus, after formation of DNA adducts, the activation of cellular pathways can lead to the avoidance of a mutagenic outcome. The understanding of the cellular mechanisms acting within the low-dose region will serve to better characterize risks from exposures to DNA-reactive agents at environmentally-relevant concentrations.
Collapse
Affiliation(s)
- Joanna Klapacz
- Toxicology & Environmental Research and Consulting, The Dow Chemical Company, Midland, MI 48674, USA.
| | - Lynn H Pottenger
- Toxicology & Environmental Research and Consulting, The Dow Chemical Company, Midland, MI 48674, USA; Current Address: Olin Corporation, Midland, MI 48674, USA
| | - Bevin P Engelward
- Department of Biological Engineering, MA Institute of Technology, Cambridge, MA 02139, USA
| | - Christopher D Heinen
- Center for Molecular Medicine, Neag Comprehensive Cancer Center, University of CT Health Center, Farmington, CT 06030, USA
| | - George E Johnson
- Institute of Life Science, College of Medicine, Swansea University, SA2 8PP, UK
| | - Rebecca A Clewell
- Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
| | - Paul L Carmichael
- Unilever, Safety & Environmental Assurance Centre, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Yeyejide Adeleye
- Unilever, Safety & Environmental Assurance Centre, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ, UK
| | - Melvin E Andersen
- Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709, USA
| |
Collapse
|
34
|
Kinetic Modeling Reveals the Roles of Reactive Oxygen Species Scavenging and DNA Repair Processes in Shaping the Dose-Response Curve of KBrO₃-Induced DNA Damage. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:764375. [PMID: 26448819 PMCID: PMC4581570 DOI: 10.1155/2015/764375] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 07/21/2015] [Indexed: 11/24/2022]
Abstract
We have developed a kinetic model to investigate how DNA repair processes and scavengers of reactive oxygen species (ROS) can affect the dose-response shape of prooxidant induced DNA damage. We used as an example chemical KBrO3 which is activated by glutathione and forms reactive intermediates that directly interact with DNA to form 8-hydroxy-2-deoxyguanosine DNA adducts (8-OH-dG). The single strand breaks (SSB) that can result from failed base excision repair of these adducts were considered as an effect downstream from 8-OH-dG. We previously demonstrated that, in the presence of effective base excision repair, 8-OH-dG can exhibit threshold-like dose-response dependence, while the downstream SSB can still exhibit a linear dose-response. Here we demonstrate that this result holds for a variety of conditions, including low levels of GSH, the presence of additional SSB repair mechanisms, or a scavenger. It has been shown that melatonin, a terminal scavenger, inhibits KBrO3-caused oxidative damage. Our modeling revealed that sustained exposure to KBrO3 can lead to fast scavenger exhaustion, in which case the dose-response shapes for both endpoints are not substantially affected. The results are important to consider when forming conclusions on a chemical's toxicity dose dependence based on the dose-response of early genotoxic events.
Collapse
|
35
|
Georgieva M, Zagorchev P, Miloshev G. Random, double- and single-strand DNA breaks can be differentiated in the method of Comet assay by the shape of the comet image. Electrophoresis 2015; 36:2553-60. [DOI: 10.1002/elps.201500269] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Revised: 06/23/2015] [Accepted: 06/28/2015] [Indexed: 01/21/2023]
Affiliation(s)
- Milena Georgieva
- Laboratory of Yeast Molecular Genetics; Institute of Molecular Biology, Bulgarian Academy of Sciences; Sofia Bulgaria
| | - Plamen Zagorchev
- Faculty of Pharmacy; Department of Medical Physics, Biophysics and Mathematics, Medical University; Plovdiv Bulgaria
| | - George Miloshev
- Laboratory of Yeast Molecular Genetics; Institute of Molecular Biology, Bulgarian Academy of Sciences; Sofia Bulgaria
| |
Collapse
|
36
|
Thomas AD, Fahrer J, Johnson GE, Kaina B. Theoretical considerations for thresholds in chemical carcinogenesis. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2015; 765:56-67. [PMID: 26281768 DOI: 10.1016/j.mrrev.2015.05.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 05/11/2015] [Accepted: 05/12/2015] [Indexed: 02/08/2023]
Abstract
There is increasing evidence for non-linear relationships for gene mutations, chromosomal aberrations and even tumor incidences in response to low doses of genotoxic carcinogens. To attain the biological relevance of such non-linear responses, there is a need to identify the underlying defense mechanisms that allow tolerance to low doses of genotoxicants. This communication discusses presumptive cancer prevention mechanisms that may contribute to thresholds, i.e. points of departure, for each endpoint, from initial DNA lesion to tumor formation. We discuss a sequential order of genome protection during carcinogenesis where genotoxicant scavenging, cellular efflux, DNA repair, elimination of damaged cells by apoptosis, autophagy, silencing by DNA damage-triggered replicative senescence, and finally, elimination of transformed (premalignant) cells by the immune system are thought to be responsible for a threshold in tumor formation. We highlight DNA repair, for which experimental evidence has been recently provided to dictate a role in PoDs. In conclusion, from a theoretical perspective it is reasonable to posit that tolerance to low dose levels exists for each requisite step of tumor formation and these tolerance mechanisms are critical in determining thresholds in chemical carcinogenesis.
Collapse
Affiliation(s)
- Adam D Thomas
- Institute of Toxicology, University Medical Centre, Mainz, Germany
| | - Jörg Fahrer
- Institute of Toxicology, University Medical Centre, Mainz, Germany
| | - George E Johnson
- Institue of Life Science, College of Medicine, Swansea, Wales, United Kingdom
| | - Bernd Kaina
- Institute of Toxicology, University Medical Centre, Mainz, Germany.
| |
Collapse
|
37
|
Chapman KE, Doak SH, Jenkins GJS. Acute dosing and p53-deficiency promote cellular sensitivity to DNA methylating agents. Toxicol Sci 2015; 144:357-65. [PMID: 25595616 DOI: 10.1093/toxsci/kfv004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Risk assessment of human exposure to chemicals is crucial for understanding whether such agents can cause cancer. The current emphasis on avoidance of animal testing has placed greater importance on in vitro tests for the identification of genotoxicants. Selection of an appropriate in vitro dosing regime is imperative in determining the genotoxic effects of test chemicals. Here, the issue of dosing approaches was addressed by comparing acute and chronic dosing, uniquely using low-dose experiments. Acute 24 h exposures were compared with equivalent dosing every 24 h over 5-day, fractionated treatment periods. The in vitro micronucleus assay was used to measure clastogenicity induced by methyl methanesulfonate (MMS) and N-methyl-N-nitrosourea (MNU) in human lymphoblastoid cell line, TK6. Quantitative real-time (qRT) PCR was used to measure mRNA level induction of DNA repair enzymes. Lowest observed genotoxic effect levels (LOGELs) for MMS were obtained at 0.7 µg/ml for the acute study and 1.0 µg/ml for the chronic study. For acute MNU dosing, a LOGEL was observed at 0.46 µg/ml, yet genotoxicity was completely removed following the chronic study. Interestingly, acute MNU dosing demonstrated a statistically significant decrease at 0.009 µg/ml. Levels of selected DNA repair enzymes did not change significantly following doses tested. However, p53 deficiency (using the TK6-isogenic cell line, NH32) increased sensitivity to MMS during chronic dosing, causing this LOGEL to equate to the acute treatment LOGEL. In the context of the present data for 2 alkylating agents, chronic dosing could be a valuable in vitro supplement to acute dosing and could contribute to reduction of unnecessary in vivo follow-up tests.
Collapse
Affiliation(s)
- Katherine E Chapman
- In vitro Toxicology Group, Institute of Life Science, College of Medicine, Swansea University, Swansea, West Glamorgan SA2 8PP, UK
| | - Shareen H Doak
- In vitro Toxicology Group, Institute of Life Science, College of Medicine, Swansea University, Swansea, West Glamorgan SA2 8PP, UK
| | - Gareth J S Jenkins
- In vitro Toxicology Group, Institute of Life Science, College of Medicine, Swansea University, Swansea, West Glamorgan SA2 8PP, UK
| |
Collapse
|
38
|
Guérard M, Baum M, Bitsch A, Eisenbrand G, Elhajouji A, Epe B, Habermeyer M, Kaina B, Martus H, Pfuhler S, Schmitz C, Sutter A, Thomas A, Ziemann C, Froetschl R. Assessment of mechanisms driving non-linear dose–response relationships in genotoxicity testing. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2015; 763:181-201. [DOI: 10.1016/j.mrrev.2014.11.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/31/2014] [Accepted: 11/01/2014] [Indexed: 01/15/2023]
|
39
|
Johnson GE, Soeteman-Hernández LG, Gollapudi BB, Bodger OG, Dearfield KL, Heflich RH, Hixon JG, Lovell DP, MacGregor JT, Pottenger LH, Thompson CM, Abraham L, Thybaud V, Tanir JY, Zeiger E, van Benthem J, White PA. Derivation of point of departure (PoD) estimates in genetic toxicology studies and their potential applications in risk assessment. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2014; 55:609-23. [PMID: 24801602 PMCID: PMC6710644 DOI: 10.1002/em.21870] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/07/2014] [Accepted: 04/11/2014] [Indexed: 05/13/2023]
Abstract
Genetic toxicology data have traditionally been employed for qualitative, rather than quantitative evaluations of hazard. As a continuation of our earlier report that analyzed ethyl methanesulfonate (EMS) and methyl methanesulfonate (MMS) dose-response data (Gollapudi et al., 2013), here we present analyses of 1-ethyl-1-nitrosourea (ENU) and 1-methyl-1-nitrosourea (MNU) dose-response data and additional approaches for the determination of genetic toxicity point-of-departure (PoD) metrics. We previously described methods to determine the no-observed-genotoxic-effect-level (NOGEL), the breakpoint-dose (BPD; previously named Td), and the benchmark dose (BMD10 ) for genetic toxicity endpoints. In this study we employed those methods, along with a new approach, to determine the non-linear slope-transition-dose (STD), and alternative methods to determine the BPD and BMD, for the analyses of nine ENU and 22 MNU datasets across a range of in vitro and in vivo endpoints. The NOGEL, BMDL10 and BMDL1SD PoD metrics could be readily calculated for most gene mutation and chromosomal damage studies; however, BPDs and STDs could not always be derived due to data limitations and constraints of the underlying statistical methods. The BMDL10 values were often lower than the other PoDs, and the distribution of BMDL10 values produced the lowest median PoD. Our observations indicate that, among the methods investigated in this study, the BMD approach is the preferred PoD for quantitatively describing genetic toxicology data. Once genetic toxicology PoDs are calculated via this approach, they can be used to derive reference doses and margin of exposure values that may be useful for evaluating human risk and regulatory decision making.
Collapse
Affiliation(s)
- G E Johnson
- Institute of Life Science, College of Medicine, Swansea University, Swansea, Wales, United Kingdom
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Determination of trace level genotoxic impurities in small molecule drug substances using conventional headspace gas chromatography with contemporary ionic liquid diluents and electron capture detection. J Chromatogr A 2014; 1361:217-28. [DOI: 10.1016/j.chroma.2014.07.099] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 07/28/2014] [Accepted: 07/31/2014] [Indexed: 11/22/2022]
|
41
|
Nakamura J, Mutlu E, Sharma V, Collins L, Bodnar W, Yu R, Lai Y, Moeller B, Lu K, Swenberg J. The endogenous exposome. DNA Repair (Amst) 2014; 19:3-13. [PMID: 24767943 PMCID: PMC4097170 DOI: 10.1016/j.dnarep.2014.03.031] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The concept of the Exposome is a compilation of diseases and one's lifetime exposure to chemicals, whether the exposure comes from environmental, dietary, or occupational exposures; or endogenous chemicals that are formed from normal metabolism, inflammation, oxidative stress, lipid peroxidation, infections, and other natural metabolic processes such as alteration of the gut microbiome. In this review, we have focused on the endogenous exposome, the DNA damage that arises from the production of endogenous electrophilic molecules in our cells. It provides quantitative data on endogenous DNA damage and its relationship to mutagenesis, with emphasis on when exogenous chemical exposures that produce identical DNA adducts to those arising from normal metabolism cause significant increases in total identical DNA adducts. We have utilized stable isotope labeled chemical exposures of animals and cells, so that accurate relationships between endogenous and exogenous exposures can be determined. Advances in mass spectrometry have vastly increased both the sensitivity and accuracy of such studies. Furthermore, we have clear evidence of which sources of exposure drive low dose biology that results in mutations and disease. These data provide much needed information to impact quantitative risk assessments, in the hope of moving towards the use of science, rather than default assumptions.
Collapse
Affiliation(s)
- Jun Nakamura
- University of North Carolina, Chapel Hill, NC, United States
| | - Esra Mutlu
- University of North Carolina, Chapel Hill, NC, United States
| | - Vyom Sharma
- University of North Carolina, Chapel Hill, NC, United States
| | - Leonard Collins
- University of North Carolina, Chapel Hill, NC, United States
| | - Wanda Bodnar
- University of North Carolina, Chapel Hill, NC, United States
| | - Rui Yu
- University of North Carolina, Chapel Hill, NC, United States
| | - Yongquan Lai
- University of North Carolina, Chapel Hill, NC, United States
| | - Benjamin Moeller
- University of North Carolina, Chapel Hill, NC, United States; Lovelace Respiratory Research Institute, Albuquerque, NM, United States
| | - Kun Lu
- University of North Carolina, Chapel Hill, NC, United States
| | - James Swenberg
- University of North Carolina, Chapel Hill, NC, United States.
| |
Collapse
|
42
|
Novel 3-nitro-1H-1,2,4-triazole-based compounds as potential anti-Chagasic drugs: in vivo studies. Future Med Chem 2014; 5:1763-76. [PMID: 24144412 DOI: 10.4155/fmc.13.108] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Chagas disease is caused by the parasite Trypanosoma cruzi, is endemic in Latin America and leads to an estimated 14,000 deaths per year and around 100 million people at risk of infection. Drugs currently used in the treatment of Chagas are old, partially effective and have numerous side effects. METHODOLOGY We have previously reported that 3-nitro-1H-1,2,4-triazole-based compounds demonstrate significant and selective activity against T. cruzi amastigotes in infected L6 cells via activation of a type I nitroreductase, specific to trypanosomatids. In the present work we evaluated in vivo 13 of these compounds based on their high in vitro potency against T. cruzi (IC50 < 1 µM) and selectivity (SI: toxicity to L6 cells/toxicity against T. cruzi amastigotes > 200). Representative compounds of different chemical classes were included. A fast luminescence assay with transgenic parasites that express luciferase, and live imaging techniques were used. A total of 11 out of 13 compounds demonstrated significant antichagasic activity when administered intraperitoneally for 5-10 days at relatively small doses. The best in vivo activity was demonstrated by amides and sulfonamide derivatives. ADMET studies were performed for specific compounds. CONCLUSION At least three compounds were identified as effective, non-toxic antichagasic agents suitable for further development.
Collapse
|
43
|
Timoroğlu İ, Yüzbaşıoğlu D, Ünal F, Yılmaz S, Aksoy H, Çelik M. Assessment of the genotoxic effects of organophosphorus insecticides phorate and trichlorfon in human lymphocytes. ENVIRONMENTAL TOXICOLOGY 2014; 29:577-587. [PMID: 22610949 DOI: 10.1002/tox.21783] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 03/21/2012] [Accepted: 03/31/2012] [Indexed: 06/01/2023]
Abstract
In vitro genotoxic effects of organophosphorus insecticides Phorate (PHR) and Trichlorfon (TCF) were investigated using four genotoxicity endpoints. Different concentration ranges between 0.25-2.00 μg mL(-1) of PHR and 2.34-37.50 μg mL(-1) of TCF were applied to lymphocytes. PHR and TCF significantly increased the frequency of chromosomal aberrations (except 2.34 μg mL(-1) for TCF) and sister chromatid exchanges at all treatment times and concentrations. Most of the used concentrations induced a significant increase in the frequency of micronuclei. Furthermore, PHR and TCF significantly decreased the mitotic index at the higher concentrations after 24- and 48-h treatments. In the comet assay, PHR and TCF significantly increased the comet tail at all concentrations. However, the comet tail intensity was significantly increased at only the highest concentration of PHR and at all concentrations of TCF. According to these results, PHR and TCF possess clastogenic, mutagenic, and DNA damaging effects in human lymphocytes in vitro.
Collapse
Affiliation(s)
- İlknur Timoroğlu
- Faculty of Science, Department of Biology, Genetic Toxicology Laboratory, Gazi University, 06500 Teknikokullar, Ankara, Turkey
| | | | | | | | | | | |
Collapse
|
44
|
Chapman KE, Thomas AD, Wills JW, Pfuhler S, Doak SH, Jenkins GJS. Automation and validation of micronucleus detection in the 3D EpiDerm™ human reconstructed skin assay and correlation with 2D dose responses. Mutagenesis 2014; 29:165-75. [PMID: 24675152 PMCID: PMC3983754 DOI: 10.1093/mutage/geu011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recent restrictions on the testing of cosmetic ingredients in animals have resulted in the need to test the genotoxic potential of chemicals exclusively in vitro prior to licensing. However, as current in vitro tests produce some misleading positive results, sole reliance on such tests could prevent some chemicals with safe or beneficial exposure levels from being marketed. The 3D human reconstructed skin micronucleus (RSMN) assay is a promising new in vitro approach designed to assess genotoxicity of dermally applied compounds. The assay utilises a highly differentiated in vitro model of the human epidermis. For the first time, we have applied automated micronucleus detection to this assay using MetaSystems Metafer Slide Scanning Platform (Metafer), demonstrating concordance with manual scoring. The RSMN assay’s fixation protocol was found to be compatible with the Metafer, providing a considerably shorter alternative to the recommended Metafer protocol. Lowest observed genotoxic effect levels (LOGELs) were observed for mitomycin-C at 4.8 µg/ml and methyl methanesulfonate (MMS) at 1750 µg/ml when applied topically to the skin surface. In-medium dosing with MMS produced a LOGEL of 20 µg/ml, which was very similar to the topical LOGEL when considering the total mass of MMS added. Comparisons between 3D medium and 2D LOGELs resulted in a 7-fold difference in total mass of MMS applied to each system, suggesting a protective function of the 3D microarchitecture. Interestingly, hydrogen peroxide (H2O2), a positive clastogen in 2D systems, tested negative in this assay. A non-genotoxic carcinogen, methyl carbamate, produced negative results, as expected. We also demonstrated expression of the DNA repair protein N-methylpurine-DNA glycosylase in EpiDerm™. Our preliminary validation here demonstrates that the RSMN assay may be a valuable follow-up to the current in vitro test battery, and together with its automation, could contribute to minimising unnecessary in vivo tests by reducing in vitro misleading positives.
Collapse
Affiliation(s)
- K E Chapman
- DNA Damage Research Group, Institute of Life Science, College of Medicine, Swansea University, Singleton Park, Swansea, Wales, SA2 8PP, UK
| | | | | | | | | | | |
Collapse
|
45
|
Leandro LF, Munari CC, Sato VLFL, Alves JM, de Oliveira PF, Mastrocola DFP, Martins SDPL, Moraes TDS, de Oliveira AI, Tozatti MG, Cunha WR, Tavares DC. Assessment of the genotoxicity and antigenotoxicity of (+)-usnic acid in V79 cells and Swiss mice by the micronucleus and comet assays. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2013; 753:101-6. [DOI: 10.1016/j.mrgentox.2013.03.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/22/2013] [Accepted: 03/24/2013] [Indexed: 10/27/2022]
|
46
|
Thomas AD, Jenkins GJS, Kaina B, Bodger OG, Tomaszowski KH, Lewis PD, Doak SH, Johnson GE. Influence of DNA repair on nonlinear dose-responses for mutation. Toxicol Sci 2013; 132:87-95. [PMID: 23288051 PMCID: PMC3576011 DOI: 10.1093/toxsci/kfs341] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Recent evidence has challenged the default assumption that all DNA-reactive alkylating agents exhibit a linear dose-response. Emerging evidence suggests that the model alkylating agents methyl- and ethylmethanesulfonate and methylnitrosourea (MNU) and ethylnitrosourea observe a nonlinear dose-response with a no observed genotoxic effect level (NOGEL). Follow-up mechanistic studies are essential to understand the mechanism of cellular tolerance and biological relevance of such NOGELs. MNU is one of the most mutagenic simple alkylators. Therefore, understanding the mechanism of mutation induction, following low-dose MNU treatment, sets precedence for weaker mutagenic alkylating agents. Here, we tested MNU at 10-fold lower concentrations than a previous study and report a NOGEL of 0.0075 µg/ml (72.8nM) in human lymphoblastoid cells, quantified through the hypoxanthine (guanine) phosphoribosyltransferase assay (OECD 476). Mechanistic studies reveal that the NOGEL is dependent upon repair of O6-methylguanine (O6MeG) by the suicide enzyme O6MeG-DNA methyltransferase (MGMT). Inactivation of MGMT sensitizes cells to MNU-induced mutagenesis and shifts the NOGEL to the left on the dose axis.
Collapse
Affiliation(s)
- Adam D Thomas
- Institute of Life Science, College of Medicine, Swansea University, SA2 8PP, UK
| | | | | | | | | | | | | | | |
Collapse
|
47
|
Dueñas-García IE, Santos-Cruz LF, Castañeda-Partida L, Castañeda-Sortibrán AN, Ordaz-Téllez MG, Sánchez-Santos A, Durán-Díaz A, Rodríguez-Arnaiz R, Heres-Pulido ME. Interactions of sulforaphane and dimethyl sulfoxide with methyl methanesulfonate, urethane, 4-nitroquinoline-1-oxide and hydrogen peroxide in the Drosophila melanogaster wing spot test. Food Chem Toxicol 2012; 50:4479-86. [PMID: 23026699 DOI: 10.1016/j.fct.2012.09.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Accepted: 09/04/2012] [Indexed: 12/31/2022]
Abstract
Sulforaphane (SF) is an isothiocyanate present in Brassicaceae, vegetables that induce the detoxification of electrophiles and reactive oxygen species. SF has been correlated with chemoprevention mechanisms against degenerative diseases. We tested if the SF had an effect against methyl methanesulfonate (MMS), urethane (URE), 4-NQO and H(2)O(2). SF (>95% purity, 0.14, 0.28, 0.56 mM) was diluted in a DMSO/Tw80/EtOH mixture (DTE) corresponding to 25, 50, 100% of lyophilized broccoli. The SF treatment (0.14 mM) was positive for small spots in the ST cross and negative in the HB cross. In the HB cross, SF (0.28 mM) was genotoxic. In the ST cross, the SF treatments showed a tendency to reduce the genotoxic damage caused by MMS, which could be explained by the radical scavenging action of the DTE mixture. In the ST cross, the frequency of small spots in the SF 0.14 mM/URE treatment was similar to that of Water/URE, which can be explained by a DTE and SF scavenger action. In both crosses, the results for the direct oxidants, 4-NQO and H(2)O(2), were different and must be related to differential modulation of CYPs expression and the SF and DTE scavenger properties.
Collapse
Affiliation(s)
- I E Dueñas-García
- Genetic Toxicology, FES Iztacala, Universidad Nacional Autónoma de México, Los Reyes Iztacala, Tlalnepantla, Estado de México, Mexico
| | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Ho TD, Joshi MD, Silver MA, Anderson JL. Selective extraction of genotoxic impurities and structurally alerting compounds using polymeric ionic liquid sorbent coatings in solid-phase microextraction: Alkyl halides and aromatics. J Chromatogr A 2012; 1240:29-44. [DOI: 10.1016/j.chroma.2012.03.080] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2012] [Revised: 03/23/2012] [Accepted: 03/26/2012] [Indexed: 11/16/2022]
|
49
|
Seager AL, Shah UK, Mikhail JM, Nelson BC, Marquis BJ, Doak SH, Johnson GE, Griffiths SM, Carmichael PL, Scott SJ, Scott AD, Jenkins GJS. Pro-oxidant induced DNA damage in human lymphoblastoid cells: homeostatic mechanisms of genotoxic tolerance. Toxicol Sci 2012; 128:387-97. [PMID: 22539617 DOI: 10.1093/toxsci/kfs152] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Oxidative stress contributes to many disease etiologies including ageing, neurodegeneration, and cancer, partly through DNA damage induction (genotoxicity). Understanding the i nteractions of free radicals with DNA is fundamental to discern mutation risks. In genetic toxicology, regulatory authorities consider that most genotoxins exhibit a linear relationship between dose and mutagenic response. Yet, homeostatic mechanisms, including DNA repair, that allow cells to tolerate low levels of genotoxic exposure exist. Acceptance of thresholds for genotoxicity has widespread consequences in terms of understanding cancer risk and regulating human exposure to chemicals/drugs. Three pro-oxidant chemicals, hydrogen peroxide (H(2)O(2)), potassium bromate (KBrO(3)), and menadione, were examined for low dose-response curves in human lymphoblastoid cells. DNA repair and antioxidant capacity were assessed as possible threshold mechanisms. H(2)O(2) and KBrO(3), but not menadione, exhibited thresholded responses, containing a range of nongenotoxic low doses. Levels of the DNA glycosylase 8-oxoguanine glycosylase were unchanged in response to pro- oxidant stress. DNA repair-focused gene expression arrays reported changes in ATM and BRCA1, involved in double-strand break repair, in response to low-dose pro-oxidant exposure; however, these alterations were not substantiated at the protein level. Determination of oxidatively induced DNA damage in H(2)O(2)-treated AHH-1 cells reported accumulation of thymine glycol above the genotoxic threshold. Further, the H(2)O(2) dose-response curve was shifted by modulating the antioxidant glutathione. Hence, observed pro- oxidant thresholds were due to protective capacities of base excision repair enzymes and antioxidants against DNA damage, highlighting the importance of homeostatic mechanisms in "genotoxic tolerance."
Collapse
Affiliation(s)
- Anna L Seager
- DNA Damage Research Group, Institute of Life Science, College of Medicine, Swansea University, SA2 8PP, UK
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
Johnson GE, Za^|^iuml;r ZM, Bodger OG, Lewis PD, Rees BJ, Verma JR, Thomas AD, Doak SH, Jenkins GJS. Investigating Mechanisms for Non-linear Genotoxic Responses, and Analysing Their Effects in Binary Combination. Genes Environ 2012. [DOI: 10.3123/jemsge.34.179] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
|