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Silva PC, Domingues L, Collins T, Oliveira R, Johansson B. Quantitative assessment of DNA damage in the industrial ethanol production strain Saccharomyces cerevisiae PE-2. FEMS Yeast Res 2018; 18:5097783. [PMID: 30219865 DOI: 10.1093/femsyr/foy101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 09/12/2018] [Indexed: 11/14/2022] Open
Abstract
Lignocellulosic hydrolysates remain one of the most abundantly used substrates for the sustainable production of second generation fuels and chemicals with Saccharomyces cerevisiae. Nevertheless, fermentation inhibitors such as acetic acid, furfural and hydroxymethylfurfural are formed during the process and can lead to slow or stuck fermentations and/or act as genotoxic agents leading to production strain genetic instability. We have developed a novel dominant deletion (DEL) cassette assay for quantification of DNA damage in both wild-type and industrial yeast strains. Using this assay, the ethanol production strain S. cerevisiae PE-2 was shown to be more resistant to hydrogen peroxide and furfural than the laboratory DEL strain RS112. Indeed, the PE-2 strain also showed a lower tendency for recombination, consistent with a more efficient DNA protection. The dominant DEL assay presented herein should prove to be a useful tool in the selection of robust yeast strains and process conditions for second generation feedstock fermentations.
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Affiliation(s)
| | - Lucília Domingues
- CEB-Centre of Biological Engineering, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal
| | - Tony Collins
- CBMA - Center of Molecular and Environmental Biology
| | - Rui Oliveira
- CEB-Centre of Biological Engineering, University of Minho, Campus de Gualtar, Braga 4710-057, Portugal.,Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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Yeast-based genotoxicity tests for assessing DNA alterations and DNA stress responses: a 40-year overview. Appl Microbiol Biotechnol 2018; 102:2493-2507. [PMID: 29423630 DOI: 10.1007/s00253-018-8783-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 01/12/2018] [Accepted: 01/14/2018] [Indexed: 10/18/2022]
Abstract
By damaging DNA molecules, genotoxicants cause genetic mutations and also increase human susceptibility to cancers and genetic diseases. Over the past four decades, several assays have been developed in the budding yeast Saccharomyces cerevisiae to screen potential genotoxic substances and provide alternatives to animal-based genotoxicity tests. These yeast-based genotoxicity tests are either DNA alteration-based or DNA stress-response reporter-based. The former, which came first, were developed from the genetic studies conducted on various types of DNA alterations in yeast cells. Despite their limited throughput capabilities, some of these tests have been used as short-term genotoxicity tests in addition to bacteria- or mammalian cell-based tests. In contrast, the latter tests are based on the emergent transcriptional induction of DNA repair-related genes via activation of the DNA damage checkpoint kinase cascade triggered by DNA damage. Some of these reporter assays have been linked to DNA damage-responsive promoters to assess chemical carcinogenicity and ecotoxicity in environmental samples. Yeast-mediated genotoxicity tests are being continuously improved by increasing the permeability of yeast cell walls, by the ectopic expression of mammalian cytochrome P450 systems, by the use of DNA repair-deficient host strains, and by integrating them into high-throughput formats or microfluidic devices. Notably, yeast-based reporter assays linked with the newer toxicogenomic approaches are becoming powerful short-term genotoxicity tests for large numbers of compounds. These tests can also be used to detect polluted environmental samples, and as effective screening tools during anticancer drug development.
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Development and validation of a high-throughput transcriptomic biomarker to address 21st century genetic toxicology needs. Proc Natl Acad Sci U S A 2017; 114:E10881-E10889. [PMID: 29203651 PMCID: PMC5754797 DOI: 10.1073/pnas.1714109114] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Standard in vitro assays to assess genotoxicity frequently generate positive results that are subsequently found to be irrelevant for in vivo carcinogenesis and human cancer risk assessment. Currently used follow-up methods, such as animal testing, are expensive and time-consuming, and the development of approaches enabling more accurate mechanism-based risk assessment is essential. We developed an in vitro transcriptomic biomarker-based approach that provides a robust biomarker reflecting stress-signaling responses. The biomarker correctly identifies the vast majority of irrelevant genotoxicity results from in vitro chromosome damage assays. TGx-DDI, a multigene biomarker for DNA damage-inducing agents, is the first biomarker that not only shows convincing interlaboratory and intralaboratory reproducibility, but also performs accurately in a system suitable for high-throughput screening. Interpretation of positive genotoxicity findings using the current in vitro testing battery is a major challenge to industry and regulatory agencies. These tests, especially mammalian cell assays, have high sensitivity but suffer from low specificity, leading to high rates of irrelevant positive findings (i.e., positive results in vitro that are not relevant to human cancer hazard). We developed an in vitro transcriptomic biomarker-based approach that provides biological relevance to positive genotoxicity assay data, particularly for in vitro chromosome damage assays, and propose its application for assessing the relevance of the in vitro positive results to carcinogenic hazard. The transcriptomic biomarker TGx-DDI (previously known as TGx-28.65) readily distinguishes DNA damage-inducing (DDI) agents from non-DDI agents. In this study, we demonstrated the ability of the biomarker to classify 45 test agents across a broad set of chemical classes as DDI or non-DDI. Furthermore, we assessed the biomarker’s utility in derisking known irrelevant positive agents and evaluated its performance across analytical platforms. We correctly classified 90% (9 of 10) of chemicals with irrelevant positive findings in in vitro chromosome damage assays as negative. We developed a standardized experimental and analytical protocol for our transcriptomics biomarker, as well as an enhanced application of TGx-DDI for high-throughput cell-based genotoxicity testing using nCounter technology. This biomarker can be integrated in genetic hazard assessment as a follow-up to positive chromosome damage findings. In addition, we propose how it might be used in chemical screening and assessment. This approach offers an opportunity to significantly improve risk assessment and reduce cost.
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Mirazizi F, Bahrami A, Haghbeen K, Shahbani Zahiri H, Bakavoli M, Legge RL. Rapid and direct spectrophotometric method for kinetics studies and routine assay of peroxidase based on aniline diazo substrates. J Enzyme Inhib Med Chem 2015; 31:1162-9. [PMID: 26526616 DOI: 10.3109/14756366.2015.1103234] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Peroxidases are ubiquitous enzymes that play an important role in living organisms. Current spectrophotometrically based peroxidase assay methods are based on the production of chromophoric substances at the end of the enzymatic reaction. The ambiguity regarding the formation and identity of the final chromophoric product and its possible reactions with other molecules have raised concerns about the accuracy of these methods. This can be of serious concern in inhibition studies. A novel spectrophotometric assay for peroxidase, based on direct measurement of a soluble aniline diazo substrate, is introduced. In addition to the routine assays, this method can be used in comprehensive kinetics studies. 4-[(4-Sulfophenyl)azo]aniline (λmax = 390 nm, ɛ = 32 880 M(-1) cm(-1) at pH 4.5 to 9) was introduced for routine assay of peroxidase. This compound is commercially available and is indexed as a food dye. Using this method, a detection limit of 0.05 nmol mL(-1) was achieved for peroxidase.
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Affiliation(s)
- Fatemeh Mirazizi
- a Department of Chemistry , Islamic Azad University of Mashhad , Mashhad , The Islamic Republic of Iran
| | - Azita Bahrami
- b National Institute for Genetic Engineering and Biotechnology , Tehran , The Islamic Republic of Iran
| | - Kamahldin Haghbeen
- c Biochemistry and Biophysics, National Institute for Genetic Engineering and Biotechnology , Tehran , The Islamic Republic of Iran
| | - Hossein Shahbani Zahiri
- d National Institute for Genetic Engineering and Biotechnology , Tehran , The Islamic Republic of Iran
| | - Mehdi Bakavoli
- e Department of Chemistry , Ferdowsi University of Mashhad , Mashhad , The Islamic Republic of Iran , and
| | - Raymond L Legge
- f Department of Chemical Engineering , University of Waterloo , Waterloo , Ontario , Canada
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Claxton LD. The history, genotoxicity, and carcinogenicity of carbon-based fuels and their emissions: Part 5. Summary, comparisons, and conclusions. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2015; 763:103-47. [DOI: 10.1016/j.mrrev.2014.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 10/04/2014] [Accepted: 10/06/2014] [Indexed: 12/19/2022]
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Sobol Z, Schiestl RH. Intracellular and extracellular factors influencing Cr(VI) and Cr(III) genotoxicity. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2012; 53:94-100. [PMID: 22020802 DOI: 10.1002/em.20679] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Accepted: 07/26/2011] [Indexed: 05/31/2023]
Abstract
Cr(VI) is a human and animal carcinogen. Cr(VI) does not interact directly with DNA and thus its genotoxicity is attributed to its intracellular reduction to Cr(III) via reactive intermediates. The resulting types of DNA damage can be grouped into two categories: (1) oxidative DNA damage and (2) Cr(III)-DNA interactions. This study examines the molecular mechanism of Cr(VI) and Cr(III) genotoxicity in an intact cell. A system screening for DNA deletions (DEL assay) was used to compare induction of chromosomal rearrangements in the yeast Saccharomyces cerevisiae following Cr(VI) and Cr(III) exposure. Both forms of chromium induced DNA deletions albeit with different dose-response curves. N-acetylcysteine had a protective effect against Cr(VI) genotoxicity at high exposure doses but had no protective effect at lower doses or against Cr(III). An oxidative DNA damage repair mutant was hypersensitive to Cr(VI) only at high exposure and the mutant was not hypersensitive to Cr(III) exposure. These data imply that oxidative stress is involved in Cr(VI) genotoxicity at high exposure concentrations and not so in Cr(III). The Cr(III)-DNA interaction appears to be an important genotoxic lesion following Cr(VI) exposure at low-exposure concentrations. The CAN forward mutation assay revealed that within the concentration ranges used for this study, Cr(III) does not cause point mutations and Cr(VI) causes a mild but statistically significant increase in point mutation only at the highest concentration tested. This study reveals that DNA deletions occurring as a result of intrachromosomal homologous recombination are a useful endpoint for studying chromium genotoxicity.
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Affiliation(s)
- Zhanna Sobol
- Department of Pathology, Geffen School of Medicine and School of Public Health, UCLA, Los Angeles, California 90095, USA
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Abstract
Positive genetic toxicity data suggest carcinogenic hazard, and this can stop a candidate pharmaceutical reaching the clinic. However, during the last decade, it has become clear that many non-carcinogens produce misleading positive results in one or other of the regulatory genotoxicity assays. These doubtful conclusions cost a lot of time and money, as they trigger additional testing of apparently genotoxic candidates, both in vitro and in animals, to discover whether the suggested hazard is genuine. This in turn means that clinical trials can be put on hold. This review describes the current approaches to the 'misleading positive' problem as well as efforts to reduce the use of animals in genotoxicity assessment. The following issues are then addressed: the application of genotoxicity testing screens earlier in development; the search for new or improved in vitro genotoxicity tests; proposed changes to the International Committee on Harmonisation guidance on genotoxicity testing [S2(R1)]. Together, developments in all these areas offer good prospects of a more rapid and cost-effective way to understand genetic toxicity concerns.
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Coy SL, Cheema AK, Tyburski JB, Laiakis EC, Collins SP, Fornace AJ. Radiation metabolomics and its potential in biodosimetry. Int J Radiat Biol 2011; 87:802-23. [PMID: 21692691 PMCID: PMC3572797 DOI: 10.3109/09553002.2011.556177] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Radiation exposure triggers a complex network of molecular and cellular responses that impacts metabolic processes and alters the levels of metabolites. Such metabolites have potential as biomarkers for radiation dosimetry. This review provides an overview of radiation signalling and metabolism, of metabolomic approaches used in the discovery phase, and of instrumentation with the potential to assess radiation injury in the field. APPROACH Recent developments in fast, high-resolution chromatography and mass spectrometry and new data analysis methods allow the quantitative assessment of thousands of metabolites based on biofluids obtained non-invasively. This complex analysis leads to the discovery-phase identification of groups of metabolites useful for screening and biodosimetry by targeted quantitative measurement. Instrumentation for target analysis can be simpler than that used for discovery, so we examine current technologies based on ion mobility. CONCLUSIONS Recent published results and ongoing studies examine the complex changes in the levels of many metabolites caused by radiation exposure, and identify groups of small-molecule biomarkers for radiation biodosimetry. Based on results showing separation orthogonal to mass, chemical noise suppression, and high sensitivity, differential mobility mass spectrometry (DMS-MS) ion mobility spectrometry appears highly promising for the development of deployable instrumentation.
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Affiliation(s)
- Stephen L. Coy
- Department of Biochemistry and Molecular & Cellular Biology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Amrita K. Cheema
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - John B. Tyburski
- Department of Biochemistry and Molecular & Cellular Biology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Evagelia C. Laiakis
- Department of Biochemistry and Molecular & Cellular Biology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Sean P. Collins
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
- Department of Radiation Medicine, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
| | - Albert J. Fornace
- Department of Biochemistry and Molecular & Cellular Biology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA
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Lynch AM, Sasaki JC, Elespuru R, Jacobson-Kram D, Thybaud V, De Boeck M, Aardema MJ, Aubrecht J, Benz RD, Dertinger SD, Douglas GR, White PA, Escobar PA, Fornace A, Honma M, Naven RT, Rusling JF, Schiestl RH, Walmsley RM, Yamamura E, van Benthem J, Kim JH. New and emerging technologies for genetic toxicity testing. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2011; 52:205-223. [PMID: 20740635 DOI: 10.1002/em.20614] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2010] [Revised: 06/02/2010] [Accepted: 06/07/2010] [Indexed: 05/29/2023]
Abstract
The International Life Sciences Institute (ILSI) Health and Environmental Sciences Institute (HESI) Project Committee on the Relevance and Follow-up of Positive Results in In Vitro Genetic Toxicity (IVGT) Testing established an Emerging Technologies and New Strategies Workgroup to review the current State of the Art in genetic toxicology testing. The aim of the workgroup was to identify promising technologies that will improve genotoxicity testing and assessment of in vivo hazard and risk, and that have the potential to help meet the objectives of the IVGT. As part of this initiative, HESI convened a workshop in Washington, DC in May 2008 to discuss mature, maturing, and emerging technologies in genetic toxicology. This article collates the abstracts of the New and Emerging Technologies Workshop together with some additional technologies subsequently considered by the workgroup. Each abstract (available in the online version of the article) includes a section addressed specifically to the strengths, weaknesses, opportunities, and threats associated with the respective technology. Importantly, an overview of the technologies and an indication of how their use might be aligned with the objectives of IVGT are presented. In particular, consideration was given with regard to follow-up testing of positive results in the standard IVGT tests (i.e., Salmonella Ames test, chromosome aberration assay, and mouse lymphoma assay) to add weight of evidence and/or provide mechanism of action for improved genetic toxicity risk assessments in humans.
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Hafer K, Rivina Y, Schiestl RH. Yeast DEL assay detects protection against radiation-induced cytotoxicity and genotoxicity: adaptation of a microtiter plate version. Radiat Res 2010; 174:719-26. [PMID: 21128795 DOI: 10.1667/rr2059.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The DEL assay in yeast detects DNA deletions that are inducible by many carcinogens. Here we use the colorimetric agent MTS to adapt the yeast DEL assay for microwell plate measurement of ionizing radiation-induced cell killing and DNA deletions. Using the microwell-based DEL assay, cell killing and genotoxic DNA deletions both increased with radiation dose between 0 and 2000 Gy. We used the microwell-based DEL assay to assess the effectiveness of varying concentrations of five different radioprotectors, N-acetyl-l-cysteine, l-ascorbic acid, DMSO, Tempol and Amifostine, and one radiosensitizer, 5-bromo-2-deoxyuridine. The microwell format of the DEL assay was able to successfully detect protection against and sensitization to both radiation-induced cytotoxicity and genotoxicity. Such radioprotection and sensitization detected by the microwell-based DEL assay was validated and compared with similar measurements made using the traditional agar-based assay format. The yeast DEL assay in microwell format is an effective tool for rapidly detecting chemical protectors and sensitizers to ionizing radiation and is automatable for chemical high-throughput screening purposes.
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Affiliation(s)
- Kurt Hafer
- Department of Radiation Oncology, David Geffen School of Medicine at UCLA and UCLA School of Public Health, Los Angeles, California 90095, USA
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Hafer K, Rivina L, Schiestl RH. Cell cycle dependence of ionizing radiation-induced DNA deletions and antioxidant radioprotection in Saccharomyces cerevisiae. Radiat Res 2010; 173:802-8. [PMID: 20518659 DOI: 10.1667/rr1661.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The yeast DEL assay is an effective method for measuring intrachromosomal recombination events resulting in DNA deletions that when occurring in mammalian cells are often associated with genomic instability and carcinogenesis. Here we used the DEL assay to measure gamma-ray-induced DNA deletions throughout different phases of yeast culture growth. Whereas yeast survival differed by only up to twofold throughout the yeast growth phase, proliferating cells in lag and early exponential growth phases were tenfold more sensitive to ionizing radiation-induced DNA deletions than cells in stationary phase. Radiation-induced DNA deletion potential was found to correlate directly with the fraction of cells in S/G(2) phase. The ability of the antioxidants l-ascorbic acid and DMSO to protect against radiation-induced DNA deletions was also measured within the different phases of yeast culture growth. Yeast cells in lag and early exponential growth phases were uniquely protected by antioxidant treatment, whereas nondividing cells in stationary phase could not be protected against the induction of DNA deletions. These results are compared with those from mammalian cell studies, and the implications for radiation-induced carcinogenesis and radioprotection are discussed.
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Affiliation(s)
- Kurt Hafer
- Departments of Radiation Oncology, Pathology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
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Elespuru RK, Agarwal R, Atrakchi AH, Bigger CAH, Heflich RH, Jagannath DR, Levy DD, Moore MM, Ouyang Y, Robison TW, Sotomayor RE, Cimino MC, Dearfield KL. Current and Future Application of Genetic Toxicity Assays: The Role and Value of In Vitro Mammalian Assays. Toxicol Sci 2009; 109:172-9. [DOI: 10.1093/toxsci/kfp067] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Guyton KZ, Kyle AD, Aubrecht J, Cogliano VJ, Eastmond DA, Jackson M, Keshava N, Sandy MS, Sonawane B, Zhang L, Waters MD, Smith MT. Improving prediction of chemical carcinogenicity by considering multiple mechanisms and applying toxicogenomic approaches. Mutat Res 2008; 681:230-240. [PMID: 19010444 DOI: 10.1016/j.mrrev.2008.10.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Revised: 10/10/2008] [Accepted: 10/14/2008] [Indexed: 11/24/2022]
Abstract
While scientific knowledge of the potential health significance of chemical exposures has grown, experimental methods for predicting the carcinogenicity of environmental agents have not been substantially updated in the last two decades. Current methodologies focus first on identifying genotoxicants under the premise that agents capable of directly damaging DNA are most likely to be carcinogenic to humans. Emphasis on the distinction between genotoxic and non-genotoxic carcinogens is also motivated by assumed implications for the dose-response curve; it is purported that genotoxicants would lack a threshold in the low dose region, in contrast to non-genotoxic agents. However, for the vast majority of carcinogens, little if any empirical data exist to clarify the nature of the cancer dose-response relationship at low doses in the exposed human population. Recent advances in scientific understanding of cancer biology-and increased appreciation of the multiple impacts of carcinogens on this disease process-support the view that environmental chemicals can act through multiple toxicity pathways, modes and/or mechanisms of action to induce cancer and other adverse health outcomes. Moreover, the relationship between dose and a particular outcome in an individual could take multiple forms depending on genetic background, target tissue, internal dose and other factors besides mechanisms or modes of action; inter-individual variability and susceptibility in response are, in turn, key determinants of the population dose-response curve. New bioanalytical approaches (e.g., transcriptomics, proteomics, and metabolomics) applied in human, animal and in vitro studies could better characterize a wider array of hazard traits and improve the ability to predict the potential carcinogenicity of chemicals.
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Affiliation(s)
- Kathryn Z Guyton
- National Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, 1200 Pennsylvania Avenue, NW Washington, DC 20460, USA.
| | - Amy D Kyle
- School of Public Health, University of California, Berkeley, CA 94720, USA
| | - Jiri Aubrecht
- Drug Safety Research and Development, Pfizer Global Research and Development, Groton, CT 06340, USA
| | | | - David A Eastmond
- Environmental Toxicology Graduate Program and Department of Cell Biology & Neuroscience, University of California, Riverside, CA 92521, USA
| | - Marc Jackson
- Integrated Laboratory Systems (ILS), Inc., P.O. Box 13501, Research Triangle Park, NC 27709, USA
| | - Nagalakshmi Keshava
- National Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, 1200 Pennsylvania Avenue, NW Washington, DC 20460, USA
| | - Martha S Sandy
- California Environmental Protection Agency, Office of Environmental Health Hazard Assessment, Oakland, CA 94612, USA
| | - Babasaheb Sonawane
- National Center for Environmental Assessment, Office of Research and Development, US Environmental Protection Agency, 1200 Pennsylvania Avenue, NW Washington, DC 20460, USA
| | - Luoping Zhang
- School of Public Health, University of California, Berkeley, CA 94720, USA
| | - Michael D Waters
- Integrated Laboratory Systems (ILS), Inc., P.O. Box 13501, Research Triangle Park, NC 27709, USA
| | - Martyn T Smith
- School of Public Health, University of California, Berkeley, CA 94720, USA
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Hontzeas N, Hafer K, Schiestl RH. Development of a microtiter plate version of the yeast DEL assay amenable to high-throughput toxicity screening of chemical libraries. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2007; 634:228-34. [PMID: 17707690 DOI: 10.1016/j.mrgentox.2007.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2007] [Revised: 06/23/2007] [Accepted: 07/03/2007] [Indexed: 10/23/2022]
Abstract
The yeast plate-based deletion (DEL) assay has been previously shown to detect a wide range of carcinogens. Of 60 compounds of known carcinogenic activity, 92% were correctly detectable with the DEL assay whereas 62% were correctly detectable with the Ames assay [W.W. Ku, J. Aubrecht, R.J. Mauthe, R.H. Schiestl, A.J. Fornace Jr., Why not start with a single test: a transformational alternative to genotoxicity hazard and risk assessment, Toxicol. Sci. (2007)]. In this manuscript we describe a modification of the yeast DEL assay into a colorimetric assay using the MTS tetrazolium compound (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt) to allow for efficient detection of chemical genotoxicity. It has been micro-scaled and can be performed in 96- or 384-well format. Chemicals previously characterized with the DEL plate-based assay were utilized to test the new well-based format, and a group of cross-linking agents, previously uncharacterized by the DEL assay, were scored for genotoxicity using this new assay format. These compounds induced a range of genotoxicity detectable with the well-based DEL assay, and a lack of sensitivity was found only at extremely low genotoxic levels determined by the plate-based DEL assay. We suggest this new well-based version of the DEL assay can be used as an economical alternative to the plate-based assay to screen large numbers of compounds, such as chemical libraries in a high-throughput screening setting.
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Affiliation(s)
- Nikos Hontzeas
- Department of Pathology, David Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
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