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Qu Y, Li R, Li X, Yang Q, Chen J, Dong Y, Xiao W, Zheng S, Wang L, Tao Y, Huang Y. Development of Animal Models for Lens and Corneal Diseases Using N-Methyl-N-Nitrosourea. Invest Ophthalmol Vis Sci 2021; 61:38. [PMID: 32721019 PMCID: PMC7425732 DOI: 10.1167/iovs.61.8.38] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Purpose N-methyl-N-nitrosourea (MNU) is an alkylating toxicant with potent mutagenic ability. This study was designed to induce apoptosis in lens epithelial cells (LECs) and corneal endothelial cells (CECs) via MNU administration. We sought to build ocular disease models of cataract and corneal endothelial decompensation. Methods MNU was delivered into the intraperitoneal cavities of neonatal rats and the anterior chambers of adult rabbits. The MNU-treated animals were then subjected to a series of functional and morphological analyses at various time points. Results MNU treatment induced pervasive apoptosis of LECs and CECs. These effects were dose and time dependent. Mature cataracts were found in neonatal rats 3 weeks after MNU treatment. Histological analysis revealed that MNU toxicity induced swelling, vacuolation, and liquefaction in lens fibers of MNU-treated rats. Pentacam examination showed that the average density of rat lens increased significantly after MNU administration. Terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) analysis showed pervasive apoptotic staining in the lenses of MNU-treated rats. In rabbit eyes, intracameral treatment with MNU induced corneal edema and significantly increased central corneal thickness, which peaked at P14. Morphological and immunohistochemical analysis showed that CECs were effectively ablated in the MNU-treated rabbits. The expression of 8-OHdG increased significantly in the cornea of MNU-treated rabbits, compared with vehicle-treated controls. Conclusions MNU is sufficient to induce ocular cell apoptosis in animal models. These models of MNU-induced cataract and corneal endothelial decompensation represent valuable tools for efforts to develop relevant therapies.
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Faustino-Rocha AI, Ferreira R, Oliveira PA, Gama A, Ginja M. N-Methyl-N-nitrosourea as a mammary carcinogenic agent. Tumour Biol 2015; 36:9095-117. [PMID: 26386719 DOI: 10.1007/s13277-015-3973-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 08/21/2015] [Indexed: 02/06/2023] Open
Abstract
The administration of chemical carcinogens is one of the most commonly used methods to induce tumors in several organs in laboratory animals in order to study oncologic diseases of humans. The carcinogen agent N-methyl-N-nitrosourea (MNU) is the oldest member of the nitroso compounds that has the ability to alkylate DNA. MNU is classified as a complete, potent, and direct alkylating compound. Depending on the animals' species and strain, dose, route, and age at the administration, MNU may induce tumors' development in several organs. The aim of this manuscript was to review MNU as a carcinogenic agent, taking into account that this carcinogen agent has been frequently used in experimental protocols to study the carcinogenesis in several tissues, namely breast, ovary, uterus, prostate, liver, spleen, kidney, stomach, small intestine, colon, hematopoietic system, lung, skin, retina, and urinary bladder. In this paper, we also reviewed the experimental conditions to the chemical induction of tumors in different organs with this carcinogen agent, with a special emphasis in the mammary carcinogenesis.
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Affiliation(s)
- Ana I Faustino-Rocha
- Department of Veterinary Sciences, School of Agrarian and Veterinary Sciences, University of Trás-os-Montes and Alto Douro, UTAD, 5001-911, Vila Real, Portugal. .,Center for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), UTAD, 5001-911, Vila Real, Portugal.
| | - Rita Ferreira
- Organic Chemistry of Natural Products and Agrifood (QOPNA), Mass Spectrometry Center, Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Paula A Oliveira
- Department of Veterinary Sciences, School of Agrarian and Veterinary Sciences, University of Trás-os-Montes and Alto Douro, UTAD, 5001-911, Vila Real, Portugal.,Center for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), UTAD, 5001-911, Vila Real, Portugal
| | - Adelina Gama
- Department of Veterinary Sciences, School of Agrarian and Veterinary Sciences, University of Trás-os-Montes and Alto Douro, UTAD, 5001-911, Vila Real, Portugal.,Animal and Veterinary Research Center (CECAV), School of Agrarian and Veterinary Sciences, UTAD, 5001-911, Vila Real, Portugal
| | - Mário Ginja
- Department of Veterinary Sciences, School of Agrarian and Veterinary Sciences, University of Trás-os-Montes and Alto Douro, UTAD, 5001-911, Vila Real, Portugal.,Center for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), UTAD, 5001-911, Vila Real, Portugal
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UV-absorption studies of interaction of karanjin and karanjachromene with ds. DNA: Evaluation of binding and antioxidant activity. OPEN CHEM 2013. [DOI: 10.2478/s11532-013-0327-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractTwo flavonoids, karanjin (Kj) and karanjachromene (Kc) have been investigated spectrophotometrically for their mode of interactions with double stranded (ds)-DNA at blood (7.4) and stomach (4.7) pH and at human body temperature (37°C). Benesi-Hildebrand equation was used to evaluate the binding constants, K b . Binding constants at both pH values and at body temperature showed stronger binding of both the flavonoids and formation of 1:1 flavonoid-DNA complex via intercalative mode. However, K b values for karanjin were evaluated to be comparatively greater than karanjachromene at both pH values. The highest value of binding constant (1.32×105 M−1) for karanjin at blood pH (7.4) demonstrated its comparatively stronger binding and greater effectiveness at this pH. Standard Gibbs free energy changes (ΔG) of flavonoid-DNA complexes were calculated as negative values and indicative of spontaneity of their binding. Both flavonoids showed significant DNA protection activity.
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John K, Pratt MM, Beland FA, Churchwell MI, McMullen G, Olivero OA, Pogribny IP, Poirier MC. Benzo[a]pyrene (BP) DNA adduct formation in DNA repair-deficient p53 haploinsufficient [Xpa(-/-)p53(+/-)] and wild-type mice fed BP and BP plus chlorophyllin for 28 days. Carcinogenesis 2012; 33:2236-41. [PMID: 22828138 DOI: 10.1093/carcin/bgs247] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We have evaluated DNA damage (DNA adduct formation) after feeding benzo[a]pyrene (BP) to wild-type (WT) and cancer-susceptible Xpa(-/-)p53(+/-) mice deficient in nucleotide excision repair and haploinsufficient for the tumor suppressor p53. DNA damage was evaluated by high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ES-MS/MS), which measures r7,t8,t9-trihydroxy-c-10-(N (2)-deoxyguanosyl)-7,8,9,10-tetrahydrobenzo[a]pyrene (BPdG), and a chemiluminescence immunoassay (CIA), using anti-r7,t8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE)-DNA antiserum, which measures both BPdG and the other stable BP-DNA adducts. When mice were fed 100 ppm BP for 28 days, BP-induced DNA damage measured in esophagus, liver and lung was typically higher in Xpa(-/-)p53(+/-) mice, compared with WT mice. This result is consistent with the previously observed tumor susceptibility of Xpa(-/-)p53(+/-) mice. BPdG, the major DNA adduct associated with tumorigenicity, was the primary DNA adduct formed in esophagus (a target tissue in the mouse), whereas total BP-DNA adducts predominated in higher levels in the liver (a non-target tissue in the mouse). In an attempt to lower BP-induced DNA damage, we fed the WT and Xpa(-/-)p53(+/-) mice 0.3% chlorophyllin (CHL) in the BP-containing diet for 28 days. The addition of CHL resulted in an increase of BP-DNA adducts in esophagus, liver and lung of WT mice, a lowering of BPdG in esophagi of WT mice and livers of Xpa(-/-)p53(+/-) mice and an increase of BPdG in livers of WT mice. Therefore, the addition of CHL to a BP-containing diet showed a lack of consistent chemoprotective effect, indicating that oral CHL administration may not reduce PAH-DNA adduct levels consistently in human organs.
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Affiliation(s)
- Kaarthik John
- Carcinogen-DNA Interactions Section, LCBG, CCR, National Cancer Institute, NIH, Bethesda, MD 20892-4255, USA
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Rahn JJ, Adair GM, Nairn RS. Use of gene targeting to study recombination in mammalian cell DNA repair mutants. Methods Mol Biol 2012; 920:445-470. [PMID: 22941622 DOI: 10.1007/978-1-61779-998-3_31] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The study of gene function has been greatly facilitated by the development of strategies to modify genomic DNA. Gene targeting is one of the most successfully applied techniques used to examine the roles of specific genes in a wide variety of model systems from yeast to mammals. Our laboratory has pioneered the use of the Chinese hamster ovary (CHO) cell culture model system to study pathways of DNA repair and recombination at the hemizygous CHO APRT locus. By using a simple and effective gene targeting method, we have generated a number of DNA repair-deficient cell lines that have been used in targeted recombination experiments to investigate pathways of recombinational repair in somatic mammalian cells. These methods can be readily customized to generate a variety of cell lines deficient in specific genes of interest and can be applied to study the roles of other DNA repair proteins in pathways of mammalian recombinational repair.
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Affiliation(s)
- Jennifer J Rahn
- Department of Molecular Carcinogenesis, Medical University of South Carolina, Charleston, SC, USA
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Louis S, Benedek K, Mowat M, Klein G, Mai S. Elongated mouse chromosomes suitable for enhanced molecular cytogenetics. Cytotechnology 2011; 44:143-9. [PMID: 19003236 DOI: 10.1007/s10616-004-2978-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2004] [Accepted: 09/07/2004] [Indexed: 11/26/2022] Open
Abstract
Characterization of genetic disorders in humans and animal models requires identification of chromosomal aberrations. However, identifying fine deletions or insertion in metaphase chromosomes has been always a challenge due to limitations of resolution. In this study we developed a rapid method for chromosome elongation using two different intercalating agents: ethidium bromide and 5-bromo-2'-deoxyuridine (BrdU), together with a short-term mitotic block using colcemid. About 70% of the chromosomes from cells that underwent this elongation procedure reached three times longer than those prepared from control cells. FISH experiments using elongated chromosomes revealed a duplicated region of chromosome 11 that was not visible in cells prepared with conventional methods.
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Affiliation(s)
- Sherif Louis
- Manitoba Institute of Cell Biology, Cancer Care Manitoba, University of Manitoba, 675 McDermot Avenue, Winnipeg, MB, R3E 0V9, Canada
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Boverhof DR, Chamberlain MP, Elcombe CR, Gonzalez FJ, Heflich RH, Hernández LG, Jacobs AC, Jacobson-Kram D, Luijten M, Maggi A, Manjanatha MG, Benthem JV, Gollapudi BB. Transgenic animal models in toxicology: historical perspectives and future outlook. Toxicol Sci 2011; 121:207-33. [PMID: 21447610 DOI: 10.1093/toxsci/kfr075] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Transgenic animal models are powerful tools for developing a more detailed understanding on the roles of specific genes in biological pathways and systems. Applications of these models have been made within the field of toxicology, most notably for the screening of mutagenic and carcinogenic potential and for the characterization of toxic mechanisms of action. It has long been a goal of research toxicologists to use the data from these models to refine hazard identification and characterization to better inform human health risk assessments. This review provides an overview on the applications of transgenic animal models in the assessment of mutagenicity and carcinogenicity, their use as reporter systems, and as tools for understanding the roles of xenobiotic-metabolizing enzymes and biological receptors in the etiology of chemical toxicity. Perspectives are also shared on the future outlook for these models in toxicology and risk assessment and how transgenic technologies are likely to be an integral tool for toxicity testing in the 21st century.
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Affiliation(s)
- Darrell R Boverhof
- Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, Michigan 48674, USA.
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Jones IM, Burkhart-Schultz K, Strout CL, Nelson DO. Studies of thioguanine-resistant lymphocytes induced by in vivo irradiation of mice. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:343-350. [PMID: 18418873 DOI: 10.1002/em.20388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The frequency of Hprt-deficient lymphocytes in mice after in vivo gamma irradiation, has been found to vary as a function of time elapsed after exposure and irradiation dose. The frequency of mutant lymphocytes in spleen was determined using an in vitro, clonogenic assay for thioguanine-resistant T-lymphocytes. Mice were exposed to single doses of 0-400 cGy from cesium-137 or to eight daily doses of 50 cGy. The time to maximum-induced mutant frequency was 3 weeks. The dose response was strikingly curvilinear at 3-5 weeks after irradiation, but less precisely defined for 10-53 weeks after exposure, being fit by either linear or quadratic dependence. Three weeks after eight daily 50 cGy exposures, mutant frequency was elevated above controls and mice exposed to 50 cGy (which were not distinct from the nonirradiated controls), but only 17% in that of mice given a single 400 cGy fraction. This fractionation effect and the curvilinearity of the early dose-response curve suggested that saturation of repair increased the yield of mutations at higher acute doses. The decline of spleen mutant frequency in mice observed between 5 and 10 weeks after irradiation may reflect selection against some mutants. The marked variation of mutant frequency, as a function of time after irradiation and of dose rate, emphasize the need to evaluate these variables carefully and consistently in future studies.
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Affiliation(s)
- Irene M Jones
- Chemistry, Materials, Earth and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California, USA.
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Ro S, Rannala B. Inferring somatic mutation rates using the stop-enhanced green fluorescent protein mouse. Genetics 2007; 177:9-16. [PMID: 17603123 PMCID: PMC2013726 DOI: 10.1534/genetics.106.069310] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2006] [Accepted: 06/13/2007] [Indexed: 02/06/2023] Open
Abstract
A new method is developed for estimating rates of somatic mutation in vivo. The stop-enhanced green fluorescent protein (EGFP) transgenic mouse carries multiple copies of an EGFP gene with a premature stop codon. The gene can revert to a functional form via point mutations. Mice treated with a potent mutagen, N-ethyl-N-nitrosourea (ENU), and mice treated with a vehicle alone are assayed for mutations in liver cells. A stochastic model is developed to model the mutation and gene expression processes and maximum-likelihood estimators of the model parameters are derived. A likelihood-ratio test (LRT) is developed for detecting mutagenicity. Parametric bootstrap simulations are used to obtain confidence intervals of the parameter estimates and to estimate the significance of the LRT. The LRT is highly significant (alpha < 0.01) and the 95% confidence interval for the relative effect of the mutagen (the ratio of the rate of mutation during the interval of mutagen exposure to the rate of background mutation) ranges from a minimum 200-fold effect of the mutagen to a maximum 2000-fold effect.
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Affiliation(s)
- Simon Ro
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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Griffin C, Waard HD, Deans B, Thacker J. The involvement of key DNA repair pathways in the formation of chromosome rearrangements in embryonic stem cells. DNA Repair (Amst) 2005; 4:1019-27. [PMID: 15979950 DOI: 10.1016/j.dnarep.2005.05.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 05/10/2005] [Accepted: 05/11/2005] [Indexed: 11/25/2022]
Abstract
It is vital that embryonic stem (ES) cells, which give rise to the diverse tissues of the mature organism, maintain genetic stability. To understand mechanisms for the prevention and causation of chromosomal instability, we have used spectral karyotyping (SKY) to analyse ES cells from wild-type and repair-gene knockout mice. We chose cells deficient in Ku70 (DNA end joining), Xrcc2 (gene conversion), Ercc1 (single-strand annealing) and Csb (transcription-coupled repair) to represent potentially-important DNA repair pathways, plus an Xpc-deficient line to examine loss of global nucleotide excision repair (NER). Spontaneous and radiation (X-ray or alpha-particle)-induced chromosome changes were assessed to measure the influence of different levels of damage severity on response. We show that most repair pathways (except for global NER) protect against chromosome changes induced by ionizing radiations, while only homology-dependent pathways protect against spontaneous chromosomal change in ES cells. However, for a given level of damage, the prevalence of different types of changes alters in the different repair-deficient lines. Thus, loss of Ercc1, Csb or Ku70 leads to increased fragment formation, but loss of Xrcc2 promotes exchanges between chromosomes. Strikingly, we found that loss of the Csb gene function specifically protects ES cells from complex exchanges, suggesting a role for transcription-associated events in complex exchange formation.
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Affiliation(s)
- Carol Griffin
- Medical Research Council, Radiation & Genome Stability Unit, Harwell, Oxfordshire OX11 0RD, England, UK
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Backendorf C, de Wit J, van Oosten M, Stout GJ, Mitchell JR, Borgstein AM, van der Horst GT, de Gruijl FR, Brouwer J, Mullenders LHF, Hoeijmakers JHJ. Repair characteristics and differentiation propensity of long-term cultures of epidermal keratinocytes derived from normal and NER-deficient mice. DNA Repair (Amst) 2005; 4:1325-36. [PMID: 16182615 DOI: 10.1016/j.dnarep.2005.07.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Revised: 07/20/2005] [Accepted: 07/21/2005] [Indexed: 01/15/2023]
Abstract
Epidermal keratinocytes constitute the most relevant cellular system in terms of DNA damage because of their continuous exposure to UV light and genotoxic chemicals from the environment. Here, we describe the establishment of long-term keratinocyte cultures from the skin of wild-type and nucleotide excision repair (NER) deficient mouse mutants. The use of media with a lowered calcium concentration and the inclusion of keratinocyte growth factor (KGF) permitted repeated passaging of the cultures and resulted in the generation of stable cell lines that proliferated efficiently. The cells retained their normal ability to engage into terminal differentiation when triggered with high calcium concentrations or after suspension in semi-solid medium. The cultures reflected the cellular characteristics (i.e. repair and transcription profiles) of the Xpa(-/-), Xpc(-/-), Csb(-/-) and Xpd(TTD) mouse models from which they were derived. For instance, in line with earlier in vivo results, Xpd(TTD) keratinocytes were disturbed in their ability to terminally differentiate in vitro. This was concluded from a delay in calcium-induced stratification and by reduced transcription of both early (keratin 10) and late (loricrin) terminal differentiation marker genes. UDS measurements in wild-type cells committed to terminal differentiation did not reveal any reduction in global DNA repair that could be indicative of differentiation associated repair (DAR) as found in neurons. UV sensitivity data revealed that in keratinocytes global genome repair contributes more to cell survival than previously concluded from fibroblast studies. It is inferred that these fully controllable in vitro cultures will be a valuable tool to assess critical parameters of genome care-taking systems in cell proliferation and differentiation.
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Affiliation(s)
- Claude Backendorf
- Laboratory of Molecular Genetics, Leiden Institute of Chemistry, Einsteinweg 55, 2333 CC Leiden, The Netherlands.
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Hoogervorst EM, van Steeg H, de Vries A. Nucleotide excision repair- and p53-deficient mouse models in cancer research. Mutat Res 2005; 574:3-21. [PMID: 15914203 DOI: 10.1016/j.mrfmmm.2005.01.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Revised: 11/29/2004] [Accepted: 01/10/2005] [Indexed: 05/02/2023]
Abstract
Cancer is caused by the loss of controlled cell growth due to mutational (in)activation of critical genes known to be involved in cell cycle regulation. Three main mechanisms are known to be involved in the prevention of cells from becoming cancerous; DNA repair and cell cycle control, important to remove DNA damage before it will be fixed into mutations and apoptosis, resulting in the elimination of cells containing severe DNA damage. Several human syndromes are known to have (partially) deficiencies in these pathways, and are therefore highly cancer prone. Examples are xeroderma pigmentosum (XP) caused by an inborn defect in the nucleotide excision repair (NER) pathway and the Li-Fraumeni syndrome, which is the result of a germ line mutation in the p53 gene. XP patients develop skin cancer on sun exposed areas at a relatively early age, whereas Li-Fraumeni patients spontaneously develop a wide variety of early onset tumors, including sarcomas, leukemia's and mammary gland carcinomas. Several mouse models have been generated to mimic these human syndromes, providing us information about the role of these particular gene defects in the tumorigenesis process. In this review, spontaneous phenotypes of mice deficient for nucleotide excision repair and/or the p53 gene will be described, together with their responses upon exposure to either chemical carcinogens or radiation. Furthermore, possible applications of these and newly generated mouse models for cancer will be given.
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Affiliation(s)
- Esther M Hoogervorst
- Laboratory of Toxicology, Pathology and Genetics, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
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Hoogervorst EM, van Oostrom CTM, Beems RB, van Benthem J, van den Berg J, van Kreijl CF, Vos JG, de Vries A, van Steeg H. 2-AAF-induced tumor development in nucleotide excision repair-deficient mice is associated with a defect in global genome repair but not with transcription coupled repair. DNA Repair (Amst) 2005; 4:3-9. [PMID: 15533832 DOI: 10.1016/j.dnarep.2004.08.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2004] [Indexed: 11/24/2022]
Abstract
The nucleotide excision repair (NER) pathway comprises two sub-pathways, transcription coupled repair (TCR) and global genome repair (GGR). To establish the importance of these separate sub-pathways in tumor suppression, we exposed mice deficient for either TCR (Csb), GGR (Xpc) or both (Xpa) to 300 ppm 2-acetylaminofluorene (in feed, ad libitum) in a unique comparative exposure experiment. We found that cancer proneness was directly linked to a defect in the GGR pathway of NER as both Xpa and Xpc mice developed significantly more liver tumors upon 2-AAF exposure than wild type or Csb mice. In contrast, a defect in TCR appeared to act tumor suppressive, leading to a lower hepatocellular tumor response in Xpa mice (tumor incidence of 25%) as compared to Xpc mice (53% tumor-bearing mice). The link between deficient GGR and tumor proneness was most pronounced in the liver, but this phenomenon was also found in the urinary bladder. As tumor induction by 2-AAF appeared almost exclusively dependent on a defect in GGR, we examined whether gene mutation induction in the non-transcribed lacZ locus could reliably predict tumor risk. Interestingly, however, short-term 2-AAF exposure induced lacZ mutant levels in Csb mice almost as high as those found in Xpa or Xpc mice. This indicates that lacZ mutant frequencies are not correlated with a specific DNA repair defect and eventual tumor outcome, at least not in the experimental design presented here.
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Affiliation(s)
- Esther M Hoogervorst
- Laboratory of Toxicology, Pathology and Genetics, National Institute of Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
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Bolon B. Genetically engineered animals in drug discovery and development: a maturing resource for toxicologic research. Basic Clin Pharmacol Toxicol 2005; 95:154-61. [PMID: 15504150 DOI: 10.1111/j.1742-7843.2004.pto950402.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Genetically engineered mice that either over-express a foreign gene (transgenic) or in which the activity of a specific gene has been removed ("knock-out") or replaced ("knock-in") will be used increasingly to investigate molecular mechanisms of disease, to evaluate innovative therapeutic targets, and to screen novel agents for efficacy and/or toxicity. Recent innovations of relevance to toxicologic researchers include the construction of genetically engineered mice with (1) multiple engineered genes, (2) mutations that can be induced at specific sites and times throughout life, and (3) the substitution of human genes for their mouse counterparts ("humanized" mice) to allow in vivo investigation of xenobiotic toxicity. Contemporary applications of genetically engineered mice in toxicology include basic mechanistic research exploiting newly engineered mouse lines as well as applied screening for genotoxicity and carcinogenicity using commercially available animals. Many caveats must be considered when interpreting genetically engineered mice-derived toxicity data, the chief of which will be the extent to which the model's phenotype has been fully characterized, the type and incidence of background lesions for the given mouse strain and engineered gene, and the possibility of misinterpreting the presence or absence of a phenotype due to compensatory physiologic processes that mask the outcome produced by the engineering event. Toxicity data acquired using genetically engineered mice currently supplements and in time likely will supplant those gathered using the present "gold standard" bioassays, as genetically engineered mice typically develop more lesions after a shorter latency period than do age- and strain-matched, wild-type mice.
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Affiliation(s)
- Brad Bolon
- GEMpath Inc., 2540 N. 400 W., Cedar City, UT 84720-8400, U.S.A.
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Prasher JM, Lalai AS, Heijmans-Antonissen C, Ploemacher RE, Hoeijmakers JHJ, Touw IP, Niedernhofer LJ. Reduced hematopoietic reserves in DNA interstrand crosslink repair-deficient Ercc1-/- mice. EMBO J 2005; 24:861-71. [PMID: 15692571 PMCID: PMC549615 DOI: 10.1038/sj.emboj.7600542] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Accepted: 12/10/2004] [Indexed: 12/15/2022] Open
Abstract
The ERCC1-XPF heterodimer is a structure-specific endonuclease involved in both nucleotide excision repair and interstrand crosslink repair. Mice carrying a genetic defect in Ercc1 display symptoms suggestive of a progressive, segmental progeria, indicating that disruption of one or both of these DNA damage repair pathways accelerates aging. In the hematopoietic system, there are defined age-associated changes for which the cause is unknown. To determine if DNA repair is critical to prolonged hematopoietic function, hematopoiesis in Ercc1-/- mice was compared to that in young and old wild-type mice. Ercc1-/- mice (3-week-old) exhibited multilineage cytopenia and fatty replacement of bone marrow, similar to old wild-type mice. In addition, the proliferative reserves of hematopoietic progenitors and stress erythropoiesis were significantly reduced in Ercc1-/- mice compared to age-matched controls. These features were not seen in nucleotide excision repair-deficient Xpa-/- mice, but are characteristic of Fanconi anemia, a human cancer syndrome caused by defects in interstrand crosslink repair. These data support the hypothesis that spontaneous interstrand crosslink damage contributes to the functional decline of the hematopoietic system associated with aging.
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Affiliation(s)
- Joanna M Prasher
- Department of Hematology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Astrid S Lalai
- Department of Cell Biology and Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | | | - Robert E Ploemacher
- Department of Hematology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Jan H J Hoeijmakers
- Department of Cell Biology and Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Ivo P Touw
- Department of Hematology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Hematology, Erasmus Medical Center, PO Box 1738, 3000 DR Rotterdam, The Netherlands. Tel.: +31 1040 87837; Fax: +31 1040 89470; E-mail:
| | - Laura J Niedernhofer
- Department of Cell Biology and Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
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