1451
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Grujicic D, Miloševic-Djordjevic O, Arsenijevic S, Marinkovic D. Treatment of Pregnant Women with a Betamimetic and Verapamil Increases the Micronuclei Frequency in Umbilical Cord Blood Lymphocytes. TOHOKU J EXP MED 2008; 215:363-71. [DOI: 10.1620/tjem.215.363] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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1452
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Jiang L, Cao J, An Y, Geng C, Qu S, Jiang L, Zhong L. Genotoxicity of acrylamide in human hepatoma G2 (HepG2) cells. Toxicol In Vitro 2007; 21:1486-92. [PMID: 17692500 DOI: 10.1016/j.tiv.2007.06.011] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Revised: 06/15/2007] [Accepted: 06/22/2007] [Indexed: 11/28/2022]
Abstract
The recent finding that acrylamide (AA), a carcinogen in animal experiments and a probable human carcinogen, is formed in foods during cooking raises human health concerns. The relevance of dietary exposure for humans is still under debate. The purpose of the study was to evaluate the possible genotoxicity of acrylamide in human hepatoma G2 (HepG2) cells, a cell line of great relevance to detect genotoxic/antigenotoxic substances, using single cell gel electrophoresis (SCGE) assay and micronucleus test (MNT). In order to clarify the underlying mechanism(s) we evaluated the intracellular generation of reactive oxygen species (ROS) and the level of oxidative DNA damage by immunocytochemical analysis of 8-hydroxydeoxyguanosine (8-OHdG). The involvement of glutathione (GSH) in the AA-induced oxidative stress was examined through treatment with buthionine sulfoximine (BSO) to deplete GSH. The results indicate that AA caused DNA strand breaks and increase in frequency of MN in HepG2 cells in a dose-dependent manner. The possible mechanism underlies the increased levels of ROS, depletion of GSH and increase of 8-OHdG formation in HepG2 cells treated with AA. We conclude that AA exerts genotoxic effects in HepG2 cells, probably through oxidative DNA damage induced by intracellular ROS and depletion of GSH.
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Affiliation(s)
- Liping Jiang
- China-Japanese Joint Institute for Medical and Pharmaceutical Science, Dalian Medical University, 465 Zhongshan Road, Dalian 116027, Liaoning, China
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1453
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Tsuboy MS, Angeli JPF, Mantovani MS, Knasmüller S, Umbuzeiro GA, Ribeiro LR. Genotoxic, mutagenic and cytotoxic effects of the commercial dye CI Disperse Blue 291 in the human hepatic cell line HepG2. Toxicol In Vitro 2007; 21:1650-5. [PMID: 17728095 DOI: 10.1016/j.tiv.2007.06.020] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2007] [Revised: 06/25/2007] [Accepted: 06/27/2007] [Indexed: 01/26/2023]
Abstract
Textile dyes are discarded into the aquatic ecosystem via industrial effluents and potentially expose humans and local biota to adverse effects. The commercial dye CI Disperse Blue 291 which contains the aminoazobenzene 2-[(2-bromo-4,6-dinitrophenyl)azo]-5(diethylamino)-4-methoxyacetanilide (CAS registry no. 56548-64-2), was tested for genotoxicity and cytotoxicity in the human hepatoma cell line HepG2, using the comet assay, micronucleus (MN) test and a cell viability test. Five different concentrations of the test compound were examined: 200 microg/ml, 400 microg/ml, 600 microg/ml, 800 microg/ml and 1000 microg/ml. An increase in comet tail length and in the frequency of MN was detected with exposure of cells to concentrations of the commercial dye from 400 microg/ml. Furthermore, the dye was found to decrease cell viability. The results of this study demonstrate for the first time the genotoxic and mutagenic effects of the dye CI Disperse Blue 291 in mammalian cells, thus stressing the need to develop non-mutagenic dyes and to invest in improving the treatment of effluents. These measures will help to prevent harmful effects that these compounds can have on humans and aquatic organisms that come in contact with them.
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Affiliation(s)
- M S Tsuboy
- Departamento de Ciências Biológicas, UNESP, Assis, SP, Brazil
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1454
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Fink K, Brink A, Vienken J, Heidland A, Stopper H. Homocysteine exerts genotoxic and antioxidative effects in vitro. Toxicol In Vitro 2007; 21:1402-8. [PMID: 17590309 DOI: 10.1016/j.tiv.2007.05.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Revised: 05/05/2007] [Accepted: 05/08/2007] [Indexed: 12/26/2022]
Abstract
INTRODUCTION Patients with end-stage renal disease suffer from increased genomic damage and cancer incidence. One possible reason is the accumulation of uremic toxins such as homocysteine (Hcy). Elevated Hcy levels--usually indicative of cardiovascular events--correlated with the genomic damage in cross-sectional studies. Therefore we investigated the genotoxic effects of Hcy in vitro. METHODS To analyse the genomic damage, micronucleus tests and the comet-assay were performed in L5178Y and HL60 cells. Additionally, the influence of Hcy on cell cycle progression, DNA-cytosine-methylation, oxidative stress levels and on the cellular glutathione content were determined. RESULTS Low millimolar concentrations of Hcy-induced micronuclei in both cell lines but did not enhance the DNA damage observed with the comet-assay. Cell cycle progression was inhibited in S-phase, while DNA-cytosine-methylation remained unchanged. Furthermore, Hcy protected cells challenged with H(2)O(2) from oxidative stress. This was accompanied by an increased cellular glutathione level. CONCLUSION Since the genotoxic effect was limited to high Hcy concentrations, a contribution of Hcy to the enhanced genomic damage in end-stage renal disease patients would only be conceivable upon local Hcy accumulation. Whether the detected antioxidant capacity of Hcy is relevant for any situation in patients remains to be elucidated.
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Affiliation(s)
- K Fink
- Institute of Pharmacology and Toxicology, University of Wuerzburg, Versbacherstrasse 9, 97078 Wuerzburg, Germany.
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1455
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Genome instability is increased in lymphocytes of women with polycystic ovary syndrome and is correlated with insulin resistance. Mutat Res 2007; 639:55-63. [PMID: 18178226 DOI: 10.1016/j.mrfmmm.2007.11.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 11/08/2007] [Accepted: 11/12/2007] [Indexed: 12/19/2022]
Abstract
BACKGROUND Polycystic ovary syndrome (PCOS) is associated with insulin resistance and reproductive and metabolic abnormalities. The potential genetic contributors to PCOS are unclear. We tested the hypothesis that genomic instability (chromosome malsegregation and DNA damage) is increased in PCOS. METHODS Overweight age, weight and BMI-matched women with (n=14) and without (n=16) PCOS (age 34.2+/-6.0 years, weight 90.7+/-14.5 kg, BMI 34.0+/-5.6 kg/m(2), mean+/-S.D.) were assessed for chromosome malsegregation (assessed by X chromosome chromogenic in situ hybridisation) and micronucleus frequency (assessed by the cytokinesis block micronucleus index) in lymphocytes. RESULTS Women with PCOS had significantly elevated genomic instability as demonstrated by a significantly higher number of binucleated lymphocytes containing micronuclei, total number of micronuclei, a higher proportion of aneuploid X chromosome signals (2:1 X and 3:1 X) and a lower proportion of normal X chromosome segregation signals (2:2 X) in binucleated lymphocytes than women without PCOS. Surrogate measures of insulin resistance positively correlated with the proportion of aneuploid cells (2:1; 3:1 X chromosome signals) and inversely with the proportion of normal cells (2:2 X chromosome signals). CONCLUSION Women with PCOS display increased genomic instability (higher micronuclei and chromosome malsegregation) compared to women without PCOS and this increase may be related to the insulin resistance phenotype.
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1456
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Guven M, Guven GS, Oz E, Ozaydin A, Batar B, Ulutin T, Hacihanefioglu S, Domanic N. DNA repair gene XRCC1 and XPD polymorphisms and their association with coronary artery disease risks and micronucleus frequency. Heart Vessels 2007; 22:355-60. [DOI: 10.1007/s00380-007-0986-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Accepted: 03/28/2007] [Indexed: 10/22/2022]
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1457
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Cassidy CL, Lemon JA, Boreham DR. Impacts of low-dose gamma-radiation on genotoxic risk in aquatic ecosystems. Dose Response 2007; 5:323-32. [PMID: 18648569 DOI: 10.2203/dose-response.07-026.cassidy] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Chinook salmon cells were exposed to gamma radiation and chromosome damage was assessed using the micronucleus assay. The salmon cells were resistant to radiation at all doses compared to human and mammalian cells. We used an indirect approach to determine if prior low dose exposures at environmental dose levels might alter the consequences of radiation exposures to high doses of radiation (adaptive response). The cells adapted but only at doses which were above levels that might be expected environmentally. The "adaptive response" endpoint was useful to show biological responses to exposure, however, under these conditions it might not help in risk assessment of aquatic organisms since the cells seem to be very resistant and environmental radiation levels are typically extremely low. Preliminary experiments were conducted on two other fish cell model systems (Rainbow Trout and Medaka) to optimize conditions for the micronucleus assay for future environmental radiation studies. Since fish cells appear to be more radiation resistant than mammalian cells, we postulate that radiation risk in the whole organism may also be lower. Therefore whole body studies designed to test effects with the specific aim of assessing relative risk between species are in process.
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Affiliation(s)
- Cheryl L Cassidy
- Medical Sciences, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada
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1458
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DNA-damaging activity and mutagenicity of 16 newly synthesized thiazolo[5,4-a]acridine derivatives with high photo-inducible cytotoxicity. Mutat Res 2007; 650:104-14. [PMID: 18160333 DOI: 10.1016/j.mrgentox.2007.10.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Revised: 05/22/2007] [Accepted: 10/07/2007] [Indexed: 11/22/2022]
Abstract
The discovery of the potent anticancer properties of natural alkaloids in the pyrido-thiazolo-acridine series has suggested that thiazolo-acridine derivatives could be of great interest. In a continuous attempt to develop DNA-binding molecules and DNA photo-cleavers, 16 new thiazolo[5,4-a]acridines were synthesized and studied for their photo-inducible DNA-intercalative, cytotoxic and mutagenic activities, by use of the DNA methyl-green bioassay, the Alamar Blue viability assay and the Salmonella mutagenicity test using strains TA97a and TA98 with and without metabolic activation and photo-activation. Without photo-activation, one compound showed a DNA-intercalative activity in the DNA major groove while three compounds displayed intercalating properties after photo-activation. In the dark, four molecules possessed cytotoxic activities against a THP1 acute monocytic leukemia cell line while 15 derivatives displayed photo-inducible cytotoxic activity against this cell line. All compounds were mutagenic in strain TA97a with metabolic activation (+S9mix) and 15 molecules were mutagenic in strain TA98 without activation (-S9mix). Study of the quantitative structure-activity relationships (QSAR) from the Salmonella mutagenicity data revealed that several descriptors could describe cytotoxic and mutagenic activities after photo-activation. From the results of the mutagenicity test, four compounds with elevated mutagenic activities were selected for additional experiments. Their capacities to induce single-strand breaks (SSB) and chromosome-damaging effects were monitored by the comet and the micronucleus assays in normal human keratinocytes. Comparison of the minimal genotoxic concentrations showed that two compounds possessed higher capacities to induce SSB after photo-activation. In the micronucleus assay, three molecules were able to induce high numbers of micronuclei following photo-activation. Overall, the results of this study confirm that acridines are predominantly genotoxic via a DNA-intercalating mechanism in the dark, while DNA-adducts were probably induced following photo-activation.
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1459
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Sodium arsenite modulates histone acetylation, histone deacetylase activity and HMGN protein dynamics in human cells. Chromosoma 2007; 117:147-57. [PMID: 17999076 DOI: 10.1007/s00412-007-0133-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2007] [Accepted: 10/16/2007] [Indexed: 10/22/2022]
Abstract
Extensive epidemiological data indicate that inorganic arsenic is associated with several types of human cancer. Nevertheless, the underlying mechanisms are poorly understood. Among its mode of action are the alterations on DNA methylation, which provoke aberrant gene expression. However, beyond DNA methylation, little is known about arsenic's effects on chromatin. In this study, we investigated the effects of sodium arsenite (NaAsO(2)) on global histone modifications and nucleosome-associated proteins. Our findings revealed that NaAsO(2) exposure significantly increases global histone acetylation. This effect was related to the inhibition of histone deacetylase (HDAC) activity because NaAsO(2) was able to inhibit HDACs comparable to the well-known HDAC inhibitor trichostatin A (TSA). Furthermore, analyses of the dynamic properties of the nucleosome-associated high mobility group N proteins demonstrate that NaAsO(2) elevates their mobility. Thus, our data suggest that NaAsO(2) induces chromatin opening by histone hyperacetylation due to HDAC inhibition and increase of the mobility of nucleosome-associated proteins. As the chromatin compaction is crucial for the regulation of gene expression as well as for genome stability, we propose that chromatin opening by NaAsO(2) may play a significant role to impart its genotoxic effects.
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1460
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Mozdarani H, Nazari E. Frequency of micronuclei in 4-8 cell mouse embryos generated after maternal gamma-irradiation in the presence and in the absence of vitamin C. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2007; 46:417-22. [PMID: 17611768 DOI: 10.1007/s00411-007-0118-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 06/14/2007] [Indexed: 05/16/2023]
Abstract
The objective of this investigation was to evaluate the frequency of chromosomal aberrations expressed as micronuclei (MN) in 4-8 cell embryos generated by gamma-irradiation of female mice in the absence and in the presence of vitamin C. Female NMRI mice were whole body exposed to 4 Gy gamma-irradiation after intraperitoneal (i.p.) injection of pregnant mare's serum gonadotrophin (PMSG) followed by injection of human chorionic gonadotrophin (HCG) and mating with non-irradiated NMRI male mice. Pregnant animals were sacrificed and embryos flushed from the oviducts and fixed on slides. Cells were treated for MN observation using standard method. To investigate the protective effect of vitamin C (ascorbic acid) on the frequency of MN, 100 mg/kg vitamin C was i.p. injected 1 h before irradiation. Results show that the frequency of MN generated in the embryos of irradiated mother compared to those of control in the non-irradiated group increased dramatically (P < 0.001). Frequency of MN in embryos generated in irradiated female mice treated with vitamin C dramatically and statistically decreased relative to the frequency observed in the irradiation only group (P < 0.001). This decrease returned the combined treatment group to a level that was not statistically different from the controls (P > 0.05). Thus, irradiation of preovulatory stage oocytes leads to stable chromosome abnormalities expressed as micronuclei in successive preimplantation embryos. Vitamin C reduces these clastogenic effects of radiation in preovulatory oocytes and thus the reduced frequency of MN in embryos is probably due to its antioxidation and radical scavenging properties.
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Affiliation(s)
- Hossein Mozdarani
- Department of Medical Genetics, Tarbiat Modares University, Tehran, Iran.
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1461
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Han W, Zhu L, Jiang E, Wang J, Chen S, Bao L, Zhao Y, Xu A, Yu Z, Wu L. Elevated sodium chloride concentrations enhance the bystander effects induced by low dose alpha-particle irradiation. Mutat Res 2007; 624:124-31. [PMID: 17560616 DOI: 10.1016/j.mrfmmm.2007.04.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2006] [Revised: 04/20/2007] [Accepted: 04/25/2007] [Indexed: 05/15/2023]
Abstract
Previous studies have shown that high NaCl can be genotoxic, either alone or combined with irradiation. However, little is known about the relationship between environmental NaCl at elevated conditions and radiation-induced bystander effects (RIBE). RIBE, which has been considered as non-targeted bystander responses, has been demonstrated to occur widely in various cell lines. In the present study, RIBE under the elevated NaCl culture condition was assessed in AG 1522 cells by both the induction of gamma-H2AX, a reliable marker of DNA double-strand break (DSB) for the early process (<1h post irradiation), and the generation of micronuclei (MN), a sensitive marker for relative long process of RIBE. Our results showed that in the absence of irradiation, NaCl at elevated concentration such as 8.0, 9.0 and 10.0g/L did not significantly increase the frequency of gamma-H2AX foci-positive cells and the number of foci per positive cell comparing with that NaCl at a normal concentration (6.8g/L). However, with 0.2cGy alpha-particle irradiation, the induced fraction of gamma-H2AX foci-positive cells and the number of induced gamma-H2AX foci per positive cell were significantly increased in both irradiated and adjacent non-irradiated regions. Similarly, the induction of MN by 0.2cGy alpha-particle irradiation also increased with the elevated NaCl concentrations. With N(G)-methyl-l-arginine, an inhibitor of nitric oxide synthase, the induced fraction of foci-positive cells was effectively inhibited both in 0.2cGy alpha-particle irradiated and adjacent non-irradiated regions under either normal or elevated NaCl conditions. These results suggested that the cultures with elevated NaCl medium magnified the damage effects induced by the low dose alpha-particle irradiation and nitric oxide generated by irradiation was also very important in this process.
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Affiliation(s)
- Wei Han
- Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
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1462
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Medvedeva NG, Panyutin IV, Panyutin IG, Neumann RD. Phosphorylation of histone H2AX in radiation-induced micronuclei. Radiat Res 2007; 168:493-8. [PMID: 17903033 DOI: 10.1667/rr0788.1] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2006] [Accepted: 05/09/2007] [Indexed: 11/03/2022]
Abstract
DNA double-strand breaks are thought to precede the formation of most radiation-induced micronuclei. Phosphorylation of the histone H2AX is an early indicator of DNA double-strand breaks. Here we studied the phosphorylation status of the histone H2AX in micronuclei after exposure of cultured cells to ionizing radiation or treatment with colchicine. In human astrocytoma SF268 cells, after exposure to gamma radiation, the proportion of gamma-H2AX-positive to gamma-H2AX-negative micronuclei increases. The majority of the gamma-H2AX-positive micronuclei are centromere-negative. The number of gamma-H2AX-positive micronuclei continues to increase even 24 h postirradiation when most gamma-H2AX foci in the main nucleus have disappeared. In contrast, in normal human fibroblasts (BJ), the proportion of gamma-H2AX-positive to gamma-H2AX-negative micronuclei remains constant, and the majority of the centromere-negative cells are gamma-H2AX-negative. Treatment of both cell lines with colchicine results in mostly centromere-positive, gamma-H2AX-negative micronuclei. Immunostaining revealed co-localization of MDC1 and ATM with gamma-H2AX foci in both main nuclei and micronuclei; however, other repair proteins, such as Rad50, 53BP1 and Rad17, that co-localized with gamma-H2AX foci in the main nuclei were not found in the micronuclei. Combination of the micronucleus assay with gamma-H2AX immunostaining provides new insights into the mechanisms of the formation and fate of micronuclei.
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Affiliation(s)
- Natalia G Medvedeva
- Department of Nuclear Medicine, Warren G. Magnuson Clinical Center, National Institutes of Health, Bethesda, Maryland 20892, USA
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1463
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Paclitaxel resistance in untransformed human mammary epithelial cells is associated with an aneuploidy-prone phenotype. Br J Cancer 2007; 97:1218-24. [PMID: 17968427 PMCID: PMC2360475 DOI: 10.1038/sj.bjc.6603936] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Despite its increasing clinical use, almost no data are currently available about paclitaxel effects on non-cancerous mammary epithelial cells. We have previously established paclitaxel-resistant sub-cell lines (paclitaxel-surviving populations, PSPs; n=20), and sensitive controls (control clones, CCs; n=10), from the untransformed human mammary epithelial cell line HME1. In this study, we aimed to establish whether paclitaxel resistance was associated with a modified sensitivity to paclitaxel-induced aneuploidy. For this purpose, we analysed basal and paclitaxel-induced chromosome missegregation, apoptosis and aberrant spindle multipolarisation as well as microtubular network composition for each subline. PSP sublines showed higher basal and paclitaxel-induced chromosome missegregation than the CC sublines. This phenomenon was associated with resistance to paclitaxel-induced apoptosis. No significant difference in paclitaxel-induced spindle pole abnormalities between CC and PSP sublines was found. Besides, we showed that a majority of PSPs display a constitutively disrupted microtubular network composition due to aberrant tubulin expression and post-translational modifications. These results clearly indicate that paclitaxel resistance in untransformed human mammary epithelial cells is related to an increased susceptibility to acquire aneuploidy in response to this agent. The consequences of these paclitaxel-associated alterations could be deleterious as they can potentially trigger tumorigenesis.
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1464
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Iarmarcovai G, Bonassi S, Botta A, Baan RA, Orsière T. Genetic polymorphisms and micronucleus formation: a review of the literature. Mutat Res 2007; 658:215-33. [PMID: 18037339 DOI: 10.1016/j.mrrev.2007.10.001] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Revised: 10/08/2007] [Accepted: 10/15/2007] [Indexed: 11/20/2022]
Abstract
The formation of micronuclei (MN) is extensively used in molecular epidemiology as a biomarker of chromosomal damage, genome instability, and eventually of cancer risk. The occurrence of MN represents an integrated response to chromosome-instability phenotypes and altered cellular viabilities caused by genetic defects and/or exogenous exposures to genotoxic agents. The present article reviews human population studies addressing the relationship between genetic polymorphisms and MN formation, and provides insight into how genetic variants could modulate the effect of environmental exposures to genotoxic agents, host factors (gender, age), lifestyle characteristics (smoking, alcohol, folate), and diseases (coronary artery disease, cancer). Seventy-two studies measuring MN frequency either in peripheral blood lymphocytes or exfoliated cells were retrieved after an extensive search of the MedLine/PubMed database. The effect of genetic polymorphisms on MN formation is complex, influenced to a different extent by several polymorphisms of proteins or enzymes involved in xenobiotic metabolism, DNA repair proteins, and folate-metabolism enzymes. This heterogeneity reflects the presence of multiple external and internal exposures, and the large number of chromosomal alterations eventually resulting in MN formation. Polymorphisms of EPHX, GSTT1, and GSTM1 are of special importance in modulating the frequency of chromosomal damage in individuals exposed to genotoxic agents and in unexposed populations. Variants of ALDH2 genes are consistently associated with MN formation induced by alcohol drinking. Carriers of BRCA1 and BRCA2 mutations (with or without breast cancer) show enhanced sensitivity to clastogens. Some evidence further suggests that DNA repair (XRCC1 and XRCC3) and folate-metabolism genes (MTHFR) also influence MN formation. As some of the findings are based on relatively small numbers of subjects, larger scale studies are required that include scoring of additional endpoints (e.g., MN in combination with fluorescent in situ hybridization, analysis of nucleoplasmic bridges and nuclear buds), and address gene-gene interactions.
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Affiliation(s)
- G Iarmarcovai
- Laboratory of Biogenotoxicology and Environmental Mutagenesis EA 1784; IFR PMSE 112, Faculty of Medecine, Université de la Méditerranée, 27 Bd Jean Moulin, 13385 Marseille Cedex 5, France.
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1465
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Sobol Z, Engel ME, Rubitski E, Ku WW, Aubrecht J, Schiestl RH. Genotoxicity profiles of common alkyl halides and esters with alkylating activity. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2007; 633:80-94. [PMID: 17644026 DOI: 10.1016/j.mrgentox.2007.05.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Revised: 04/25/2007] [Accepted: 05/04/2007] [Indexed: 11/15/2022]
Abstract
Drug synthesis and/or formulation can generate genotoxic impurities. For instance, strong acid/alcohol interactions during the process of drug salt formation produce alkylating agents such as alkyl halides and alkyl esters of alkyl sulfonic acids. The genotoxicity of a few classic alkylating agents such as methyl and ethyl methanesulfonate have been previously well characterized, whereas the majority of compounds from this class have only been tested in the Salmonella reversion assay. Therefore, the goal of this study was to investigate clastogenicity and DEL recombination profiles of 22 halogenated alkanes and alkylesters of sulfuric and alkane-, aryl-sulfonic acids using a battery of cellular and molecular assays. The in-vitro micronucleus assay in CHO cells was used to measure clastogenicity and the deletion recombination (DEL) assay in S. cerevisiae provided a measure of DNA deletions. We also examined the compounds' reactivity towards 4-(p-nitrobenzyl)pyridine (NBP), a surrogate molecule for biological ring nitrogens. Methylating agents were most potent in all three assays and the alkyl chlorides evaluated in our study were negative in all three assays. Also, a strong correlation was found between the MN, DEL and NBP assays. In summary, this study contributes to a better understanding of the genotoxic properties of common alkyl halides and alkyl esters with alkylating activity and might provide guidance for managing risk of genotoxic process-related impurities of drug substances and products.
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Affiliation(s)
- Z Sobol
- Department of Pathology, Geffen School of Medicine, UCLA, Los Angeles, CA 90095, USA
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1466
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Chauhan LKS, Kumar M, Paul BN, Goel SK, Gupta SK. Cytogenetic effects of commercial formulations of deltamethrin and/or isoproturon on human peripheral lymphocytes and mouse bone marrow cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2007; 48:636-43. [PMID: 17685461 DOI: 10.1002/em.20330] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The cytogenetic effects of deltamethrin (DEL) and/or isoproturon (ISO) were examined in human lymphocytes and mouse bone marrow cells. Peripheral lymphocytes were exposed to DEL (2.5, 5, 10, or 20 microM), ISO (25, 50, 100, or 200 microM), or DEL + ISO (2.5 + 25, 5 + 50, 10 + 100, or 20 + 200 microM) and cytogenic effects were evaluated via chromosomal aberrations (CA) and the cytokinesis-block micronucleus assay (CBMN). Mice were orally gavaged to single dose of DEL (6.6 mg/kg), ISO (670 mg/kg), or DEL+ISO (6.6 + 670 mg/kg) for 24 hr or to DEL (3.3 mg/kg/day), ISO (330 mg/kg/day), or DEL + ISO (3.3 + 330 mg/kg/day) for 30 days and analyzed for CA. DEL induced a significant frequency of CA at 10 microM whereas ISO (25-100 microM) alone, or in combination with DEL, did not show any significant effect. Micronucleus (MN) induction was observed to be concentration-dependent though significant frequencies were observed at 5 microM DEL, 100 microM ISO, or 5 + 50 microM DEL + ISO. In mice, DEL inhibited the mitotic index (MI) significantly (P < 0.001) at 24 hr while ISO alone, or in combination with DEL, did not cause any statistically significant effect. Following a 24 hr exposure, DEL and ISO alone induced significant (P < 0.01) frequencies of CA, whereas DEL + ISO in combination did not. Furthermore, 30 days exposure of ISO significantly inhibited the MI (P < 0.02 or < 0.01) and induced CA while DEL alone, or in combination with ISO, resulted in no significant effect on CA or the MI. The present findings indicate that the in vitro and in vivo exposure of a commercial formulation of DEL can cause genotoxic effects in mammals. However, the coexposure of DEL and ISO did not show additive effects, but instead demonstrated somewhat reduced genotoxicity.
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Affiliation(s)
- Lalit K S Chauhan
- Cell Biology Division, Industrial Toxicology Research Centre, Lucknow, India
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1467
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Go SY, Kwon KJ, Park SN, Sheen YY. Genetic Toxicity Test of Emodin by Ames, Micronucleus, Comet Assays and Microarray Analysis Showing Differential Result. Biomol Ther (Seoul) 2007. [DOI: 10.4062/biomolther.2007.15.3.192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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1468
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Guery S, Floersheim P, Kaupmann K, Froestl W. Syntheses and optimization of new GS39783 analogues as positive allosteric modulators of GABA B receptors. Bioorg Med Chem Lett 2007; 17:6206-11. [PMID: 17884493 PMCID: PMC2278029 DOI: 10.1016/j.bmcl.2007.09.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 09/03/2007] [Accepted: 09/05/2007] [Indexed: 11/21/2022]
Abstract
The optimization of GS39783 into potent, selective, and safe positive allosteric modulators of GABA(B) receptors is presented.
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Affiliation(s)
- Sébastien Guery
- Novartis Institutes for Biomedical Research, Neuroscience, Novartis Pharma A.G., Basel, Switzerland.
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1469
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Molecular biomonitoring of a population of nurses handling antineoplastic drugs. Mutat Res 2007; 638:75-82. [PMID: 17928012 DOI: 10.1016/j.mrfmmm.2007.08.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 08/27/2007] [Accepted: 08/31/2007] [Indexed: 11/21/2022]
Abstract
Many antineoplastic drugs have been found to have carcinogenic, mutagenic and teratogenic activity and so hospital personnel handling these substances are potentially exposed to health risk. Understanding this risk derived from protracted occupational exposure has great relevance even if the workers normally adopt individual and environmental protective measures. To address this question we have studied the presence of DNA and chromosome damage in a population of nurses employed in Italian oncology units and in matched controls. We used the comet assay to evidence the presence of DNA strand breaks, due to both acute and chronic exposure, and the micronucleus (MN) test, which is a measure of clastogenic and aneugenic events. Furthermore, since the individual response to the exogenous insults may be genetically determined, we studied the possible influence of single nucleotide polymorphism in XRCC1 and XRCC3 DNA repair genes on induced genetic damage. We also considered the effects of confounding factors like smoking, age and gender. The results indicated that the exposed subjects had significantly high levels of genetic damage. Age and gender were associated with increased values in MN, both in control and in exposed groups; the smoking habit affects MN frequency in controls, but not in workers. Furthermore we found that exposed subjects bearing at least one XRCC1 variant allele (399Gln) show higher values of MN. The present data provide the evidence to show that occupational exposure to antineoplastic drugs, even if in safety controlled conditions, represents a serious health risk. Furthermore we have shown that the presence of XRCC1 genetic polymorphism could contribute to increase the genetic damage in susceptible individuals who are occupationally exposed to dangerous substances.
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1470
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Zhang Z, Che W, Liang Y, Wu M, Li N, Shu Y, Liu F, Wu D. Comparison of cytotoxicity and genotoxicity induced by the extracts of methanol and gasoline engine exhausts. Toxicol In Vitro 2007; 21:1058-65. [PMID: 17512694 DOI: 10.1016/j.tiv.2007.04.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 02/25/2007] [Accepted: 04/02/2007] [Indexed: 11/22/2022]
Abstract
Gasoline engine exhaust has been considered a major source of air pollution in China, and methanol is considered as a potential substitute for gasoline fuel. In this study, the genotoxicity and cytotoxicity of organic extracts of condensate, particulate matters (PM) and semivolatile organic compounds (SVOC) of gasoline and absolute methanol engine exhaust were examined by using MTT assay, micronucleus assay, comet assay and Ames test. The results have showed that gasoline engine exhaust exhibited stronger cytotoxicity to human lung carcinoma cell lines (A549 cell) than methanol engine exhaust. Furthermore, gasoline engine exhaust increased micronucleus formation, induced DNA damage in A549 cells and increased TA98 revertants in the presence of metabolic activating enzymes in a concentration-dependent manner. In contrast, methanol engine exhaust failed to exhibit these adverse effects. The results suggest methanol may be used as a cleaner fuel for automobile.
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Affiliation(s)
- Zunzhen Zhang
- Department of Environmental Health, West China College of Public Health, Sichuan University, No. 16, Section 3, Ren Min Nan Road, Chengdu 610041, People's Republic of China.
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1471
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Oztas S, Salman AB, Tatar A, Yigiter M, Yazgi H, Ertek M, Yesilyurt A, Ocak Z, Kursad H. Genotoxic effect of albendazole in pediatric patients with hepatic hydatid disease. Int J Infect Dis 2007; 11:446-9. [PMID: 17331781 DOI: 10.1016/j.ijid.2007.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2006] [Revised: 12/18/2006] [Accepted: 01/16/2007] [Indexed: 10/23/2022] Open
Abstract
OBJECTIVE Hydatid disease occurs throughout the world and is treated with both surgery and medical administration of albendazole. Some adverse effects of albendazole are known. However, its genotoxic effect on humans has not been reported yet. In this study, we aimed to investigate the genotoxic effect of albendazole on human lymphocytes in vivo. METHODS The study involved 14 children (eight males and six females) who had undergone operations for hepatic hydatid disease. The ages of the patients ranged from 6 to 13 years. Genotoxicity of albendazole was evaluated as the frequency of sister chromatid exchange (SCE) and micronucleated cells in the patient's lymphocytes. Prior to and after albendazole treatment, blood samples were obtained from these patients for SCE and micronucleus (MN) studies. SCE and MN frequencies of the patients were measured separately before and after albendazole treatment. RESULTS All patient SCE values increased significantly after albendazole administration (p<0.001). Similarly, MN frequencies in all the patients increased significantly following albendazole treatment (p<0.001). CONCLUSION This study revealed that both SCE and MN frequencies are higher after albendazole treatment. The results suggest that albendazole may be genotoxic to human lymphocytes in vivo.
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Affiliation(s)
- Sitki Oztas
- Department of Medical Genetics, Ataturk University Medical Faculty, 25240 Erzurum, Turkey.
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1472
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Han W, Wu L, Hu B, Zhang L, Chen S, Bao L, Zhao Y, Xu A, Yu Z. The early and initiation processes of radiation-induced bystander effects involved in the induction of DNA double strand breaks in non-irradiated cultures. Br J Radiol 2007; 80 Spec No 1:S7-12. [PMID: 17704329 DOI: 10.1259/bjr/44550200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The initiation and the early process of bystander response induced by low dose alpha-particle irradiation are very important for understanding the mechanisms underlying the bystander response. Using a 1 cGy alpha-particle to irradiate 50% of the area of a rectangular mylar dish, time-dependent DNA double strand breaks (DSBs) were induced shortly after irradiation in AG1522 cells, located either in the irradiated area or in the non-irradiated bystander area, reaching a maximum 30 min post irradiation. Medium transfer experiments showed that the conditioned medium harvested from the irradiated culture induced excessive DNA DSBs in the medium recipient cells, and the DSB-inducing ability of the medium showed was time-dependent. The medium transfer results indicated that the soluble bystander signalling molecule(s) had been generated very soon (probably less than 2.5 min) after irradiation and exist continuously to 30 min although the production of signalling molecule(s) decreased after 10 min post irradiation. Pre-treatment with dimethyl sulphoxide (DMSO) eliminated the DNA DSB-inducing ability of the conditioned medium, as well as the formation of excessive DNA DSBs in both irradiated and non-irradiated bystander areas, indicating that reactive oxygen/nitrogen species etc. might be involved in these processes.
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Affiliation(s)
- W Han
- Key Laboratory of Ion Beam Bioengineering, Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui 230031, People's Republic of China
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1473
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Lee YJ, Kang SJ, Kim BM, Kim YJ, Woo HD, Chung HW. Cytotoxicity of honeybee (Apis mellifera) venom in normal human lymphocytes and HL-60 cells. Chem Biol Interact 2007; 169:189-97. [PMID: 17658502 DOI: 10.1016/j.cbi.2007.06.036] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 06/04/2007] [Accepted: 06/12/2007] [Indexed: 11/19/2022]
Abstract
Whole bee venom (BV) is used to treat inflammatory diseases in Korean traditional medicine. Various studies have demonstrated anti-inflammatory and anticancer effects of BV. The toxicity of individual components of BV has been widely studied, although few studies have reported on the toxicity of BV. We sought to evaluate the cytotoxicity of BV in normal human lymphocytes and HL-60 cells. When cells were treated with BV at concentrations of 1 or 5 microg/ml, BV induced cell death in a time-dependent manner until 24 h, but these cytotoxic effects ended thereafter. When cells were treated with BV at a concentration of 10 microg/ml, however, viability decreased until 72 h, which may have been due to the half-life of BV. Whole BV also inhibited proliferation in these cells. BV induced DNA fragmentation and micronuclei in HL-60 cells and DNA fragmentation in human lymphocytes. Phosphate and tensin homolog (PTEN) up-regulation in HL-60 cells may induce S-phase cell cycle arrest. Forkhead transcription factor (FKHR and FKHRL1) up-regulation in human lymphocytes by whole BV treatment may be involved in the repair of damaged DNA and reduce genotoxicity. Based on these results, whole BV may exert cytotoxicity in these two cells in a different fashion.
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Affiliation(s)
- Young Joon Lee
- School of Public Health and Institute of Health and Environment, Seoul National University, Seoul 110-460, Republic of Korea
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1474
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Dönmez-Altuntas H, Dumlupinar G, Imamoglu N, Hamurcu Z, Liman BC. Effects of the mycotoxin citrinin on micronucleus formation in a cytokinesis-block genotoxicity assay in cultured human lymphocytes. J Appl Toxicol 2007; 27:337-41. [PMID: 17265422 DOI: 10.1002/jat.1209] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Some mycotoxins produced by microfungi are capable of causing disease and death in animals and humans. In the present study, the mycotoxin citrinin (CTN) was evaluated for its genotoxic effects to human peripheral blood lymphocytes from six different individuals. Lymphocyte cultures were treated for 48 h with CTN at six different concentrations between 10 and 100 microM. Lymphocyte cultures were also incubated with 0.1 microM mitomycin c (MMC) as a positive control, and 0.5% absolute ethanol as a vehicle control.CTN caused a significant concentration-dependent increase in micronucleus (MN) frequency in human lymphocytes. At the 60 microM, 80 microM and 100 microM concentrations, CTN was found to induce MN in cytokinesis-blocked lymphocytes in comparison with negative controls (P = 0.014). All the CTN concentrations also led to a clear decrease in the percentages of binucleated/mononucleated cells (P = 0.014). These results indicate that CTN at high concentrations is genotoxic in cultured human lymphocytes.
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1475
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Cho YH, Jeon HK, Chung HW. Effects of extremely low-frequency electromagnetic fields on delayed chromosomal instability induced by bleomycin in normal human fibroblast cells. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2007; 70:1252-8. [PMID: 17654242 DOI: 10.1080/15287390701429281] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
This study was carried out to examine the interaction of extremely low-frequency electromagnetic fields (ELF-EMF) on delayed chromosomal instability by bleomycin (BLM) in human fibroblast cells. A micronucleus-centromere assay using DNA probes for chromosomes 1 and 4 was performed and a 60-Hz ELF-EMF of 0.8 mT field strength was applied either alone or with BLM throughout the culture period. The frequencies of micronuclei (MN) and aneuploidy were analyzed at 28, 88, and 240 h after treatment with BLM. The coexposure of cells to BLM and ELF-EMF led to a significant increase in the frequencies of MN and aneuploidy compared to the cells treated with BLM alone. No difference was observed between field-exposed and sham-exposed control cells. The frequency of MN induced by BLM was increased at 28 h, and further analysis showed a persistent increase up to 240 h, but the new levels were not significantly different from the level at 28 h. BLM increased the frequencies of aneuploidy at 28, 88, and 240 h, and significantly higher frequency of aneuploidy was observed in the cells analyzed at 240 h compared to the cells examined at 28 h. No interaction of ELF-EMF on delayed chromosomal instability by BLM was observed. Our results suggest that ELF-EMF enhances the cytotoxicity of BLM. BLM might induce delayed chromosomal instability, but no effect of ELF-EMF was observed on the BLM-induced delayed chromosomal instability in fibroblast cells.
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Affiliation(s)
- Yoon Hee Cho
- School of Public Health and Institute of Health and Environment, Seoul National University, Seoul, Republic of Korea
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1476
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Da Silva GN, De Camargo EA, Salvadori DMF, Ribeiro DA. Genetic damage in human peripheral lymphocytes exposed to antimicrobial endodontic agents. ACTA ACUST UNITED AC 2007; 104:e58-61. [PMID: 17560139 DOI: 10.1016/j.tripleo.2007.02.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Accepted: 02/13/2007] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Formocresol, paramonochlorophenol, or calcium hydroxide have been widely used in dental practice to eradicate bacteria and consequently to produce root canal disinfection. Taking into consideration strong evidence for a relationship between DNA damage and carcinogenesis, the purpose of the present study was to evaluate the genotoxic effects of antimicrobial endodontic compounds in human peripheral lymphocytes by single-cell gel (comet) assay. This technique detects DNA strand breaks in individual cells. STUDY DESIGN A total of 10 microL of the tested substance solution (formocreso1, paramonochlorofeno1, and calcium hydroxide at 100-microg/mL concentration) was added to human peripheral lymphocytes from 10 volunteers for 1 hour at 37 degrees C. The negative control group was treated with vehicle control (PBS) for 1 hour at 37 degrees C, as well. For the positive control group, lymphocytes were exposed to hydrogen peroxide at 100 microM during 5 minutes on ice. RESULTS No DNA breakage was detected after a treatment of peripheral lymphocytes by formocresol, paramonochlorophenol, or calcium hydroxide at 100 microg/mL. CONCLUSIONS In summary, our results indicate that exposure to formocresol, paramonochlorophenol, or calcium hydroxide may not be a factor that increases the level of DNA lesions in human peripheral lymphocytes as detected by single-cell gel (comet) assay.
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Affiliation(s)
- Glenda N Da Silva
- Department of Pathology, Botucatu Medical School, Sao Paulo State University, Sao Paulo, Brazil
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1477
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Gajski G, Ravlic S, Capuder Z, Garaj-Vrhovac V. Use of sensitive methods for detection of DNA damage on human lymphocytes exposed to p,p'-DDT: Comet assay and new criteria for scoring micronucleus test. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART. B, PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES 2007; 42:607-13. [PMID: 17701695 DOI: 10.1080/03601230701465445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Wide distribution, stability and long persistence in the environment of dichlorodiphenyltrichloroethane (DDT), probably the best-known and most useful insecticide in the world, imposes the need for further examination of the effect of this chemical on human health and especially on the human genome. In this study, peripheral blood human lymphocytes from a healthy donor were exposed to 0.025 mg/L concentration of p,p'-DDT at different time periods (1, 2, 24 and 48 h). For the assessment of genotoxic effect, the new criteria for scoring micronucleus test and alkaline comet assay were used. Both methods showed that p,p'-DDT induces DNA damage in low concentration used in this research. Results of micronucleus test showed a statistically significant (p < 0.05) genotoxic effect of p,p'-DDT on human lymphocytes compared with corresponding control and a different exposure time. A comet assay also showed increased DNA damage caused in p,p'-DDT-exposed human lymphocytes than in corresponding control cells for the tail length. Results obtained by measuring the level of DNA migration and incidence of micronuclei (MN), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) indicate the sensitivity of these tests and their application in detection of primary genome damage after long-term exposure to establish the effect of p,p'-DDT on human genome.
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Affiliation(s)
- Goran Gajski
- Institute for Medical Research and Occupational Health, Zagreb, Croatia.
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1478
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Glouib K, Hilali A, Kettani SE, Verschaeve L. Cytogenetic biomonitoring of the Mzamza population exposed to untreated wastewaters. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2007; 79:231-6. [PMID: 17639334 DOI: 10.1007/s00128-007-9180-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Accepted: 06/01/2007] [Indexed: 05/16/2023]
Abstract
A cytogenetic biomonitoring study was performed on people from the Mzamza community near Settat, Morocco. These subjects live in and near the Bou Moussa valley where wastewaters from a great number of industries are discharged without any treatment. This wastewater is used as a source of drinking water for their cattle and irrigation of their land. The Mzamza population is therefore presumably exposed to continuous low doses of different kinds of pollutants. Our study demonstrated significant increases in micronucleated white blood cells indicating a considerable genetic risk in these subjects.
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Affiliation(s)
- K Glouib
- Laboratory of Cytogenetics and Toxicogenetics, FST, PO Box 577, Settat, Morocco
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1479
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Utani KI, Kawamoto JK, Shimizu N. Micronuclei bearing acentric extrachromosomal chromatin are transcriptionally competent and may perturb the cancer cell phenotype. Mol Cancer Res 2007; 5:695-704. [PMID: 17606478 DOI: 10.1158/1541-7786.mcr-07-0031] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Extrachromosomal double minutes (DM) bear amplified genes that contribute to the malignancy of human cancer cells. A novel intracellular behavior of DMs resulted in their selective entrapment within micronuclei; opening the vista, this could perturb the cancer cell phenotype if genes located on DMs were expressed in micronuclei. Here, using fluorescence in situ hybridization, we detected transcripts in DM-enriched micronuclei. Visualization of DMs and their transcripts in live cells showed that DMs are as actively transcribed in the micronuclei and nuclei. Moreover, pulse-incorporated bromouridine was detected in the micronuclei, and the transcripts eventually exited from the micronuclei, similar to the behavior of nuclear transcripts. This apparently normal pattern of gene expression in DM-enriched micronuclei was restricted to micronuclei associated with lamin B, and lamin B association was more frequent for micronuclei that incorporated DMs than for those that incorporated a chromosome arm. The frequency of lamin B-associated micronuclei increased after entry into S phase, and accordingly, there was a concomitant increase in transcription in micronuclei. Taken together, these results indicate that the expression of genes on DMs can be temporally altered by their incorporation into micronuclei. This may be relevant for a broad spectrum of other extrachromosomal elements.
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Affiliation(s)
- Koh-ichi Utani
- Graduate School of Biosphere Science, Hiroshima University, 1-7-1 Kagamiyama, Higashi-hiroshima 739-8521, Japan
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1480
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Rosa RM, Moura DJ, Romano E Silva AC, Saffi J, Pêgas Henriques JA. Antioxidant activity of diphenyl diselenide prevents the genotoxicity of several mutagens in Chinese hamster V79 cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2007; 631:44-54. [PMID: 17507284 DOI: 10.1016/j.mrgentox.2007.04.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2007] [Revised: 04/03/2007] [Accepted: 04/04/2007] [Indexed: 12/28/2022]
Abstract
Diphenyl diselenide (DPDS) is an electrophilic reagent used in the synthesis of a variety of pharmacologically active organic selenium compounds. Studies have shown its antioxidant, hepatoprotective, neuroprotective, anti-inflammatory, and antinociceptive effects. We recently showed the antioxidant effect of DPDS in V79 cells, and established the beneficial and toxic doses of this compound in this cell line. Here, we report the antigenotoxic and antimutagenic properties of DPDS, investigated by using a permanent lung fibroblast cell line derived from Chinese hamsters. We determined the cytotoxicity by clonal survival assay, and evaluated DNA damage in response to several mutagens by comet assay and micronucleus test in binucleated cells. In the clonal survival assay, at concentrations ranging from 1.62 to 12.5microM, DPDS was not cytotoxic, while at concentrations up to 25microM, it significantly decreased survival. The treatment with this organoselenium compound at non-cytotoxic dose range increased cell survival after challenge with hydrogen peroxide, methyl-methanesulphonate, and UVC radiation, but did not protect against 8-methoxypsoralen plus UVA-induced cytotoxicity. In addition, the treatment prevented induced DNA damage, as verified in the comet assay. The mutagenic effect of these genotoxins, as measured by the micronucleus test, similarly attenuated or prevented cytotoxicity and DNA damage. Treatment with DPDS also decreased lipid peroxidation levels after exposure to hydrogen peroxide MMS, and UVC radiation, and increased glutathione peroxidase activity in the extracts. Our results clearly demonstrate that DPDS at low concentrations presents antimutagenic properties, which are most probably due to its antioxidant properties.
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Affiliation(s)
- Renato Moreira Rosa
- Departamento de Biofísica e Centro de Biotecnologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
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1481
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Chan KL, North PS, Hickson ID. BLM is required for faithful chromosome segregation and its localization defines a class of ultrafine anaphase bridges. EMBO J 2007; 26:3397-409. [PMID: 17599064 PMCID: PMC1933408 DOI: 10.1038/sj.emboj.7601777] [Citation(s) in RCA: 323] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2007] [Accepted: 05/31/2007] [Indexed: 11/08/2022] Open
Abstract
Mutations in BLM cause Bloom's syndrome, a disorder associated with cancer predisposition and chromosomal instability. We investigated whether BLM plays a role in ensuring the faithful chromosome segregation in human cells. We show that BLM-defective cells display a higher frequency of anaphase bridges and lagging chromatin than do isogenic corrected derivatives that eptopically express the BLM protein. In normal cells undergoing mitosis, BLM protein localizes to anaphase bridges, where it colocalizes with its cellular partners, topoisomerase IIIalpha and hRMI1 (BLAP75). Using BLM staining as a marker, we have identified a class of ultrafine DNA bridges in anaphase that are surprisingly prevalent in the anaphase population of normal human cells. These so-called BLM-DNA bridges, which also stain for the PICH protein, frequently link centromeric loci, and are present at an elevated frequency in cells lacking BLM. On the basis of these results, we propose that sister-chromatid disjunction is often incomplete in human cells even after the onset of anaphase. We present a model for the action of BLM in ensuring complete sister chromatid decatenation in anaphase.
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Affiliation(s)
- Kok-Lung Chan
- Cancer Research UK Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Phillip S North
- Cancer Research UK Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Ian D Hickson
- Cancer Research UK Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
- Cancer Research UK Oxford Cancer Centre, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK. Tel.: +44 1865 222 417; Fax: +44 1865 222 431; E-mail:
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1482
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Aleisa AM, Al-Rejaie SS, Bakheet SA, Al-Bekari AM, Al-Shabanah OA, Al-Majed A, Al-Yahya AA, Qureshi S. Effect of metformin on clastogenic and biochemical changes induced by adriamycin in Swiss albino mice. Mutat Res 2007; 634:93-100. [PMID: 17693128 DOI: 10.1016/j.mrgentox.2007.06.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Revised: 05/11/2007] [Accepted: 06/21/2007] [Indexed: 12/12/2022]
Abstract
Diabetes mellitus (DM) is a chronic disease that is characterized by deteriorating glycemic control. The disease is known to be caused by imbalance between reactive oxygen species (ROS) and antioxidant defense systems. Hyperglycemia is commonly observed in a wide variety of diseases, including cancer. Although, therapy against glycemic control, is used in all these diseases, the diabetic cancer patients are on additional therapy with anticancer drugs. The objective of present study was to study if Glucophage (metformin), a very popular antidiabetic agent can avert the mutagenicity and lipid peroxidation caused by adriamycin (ADR), which is a commonly used cytotoxic drug. The experimental protocol included oral treatment of mice with different doses (62.5, 125 and 250 mg/kg day) of metformin for 7 days. Some mice in each group were injected i.p. with ADR (15 mg/kg). In each case animals were killed, 30 or 24, 48 and 72 h after the last treatment and femurs were excised for cytological studies by micronucleus test. Additional experiments on estimation of glutathione (GSH) and malondialdehyde (MDA) were undertaken in blood and serum, respectively. Twenty-four hour after the treatment, blood from each mouse was collected from heart and preserved for analysis. The results obtained revealed that pretreatment with metformin: (i) reduced the ADR-induced frequency of micronuclei without any alteration in its cytotoxicity and (ii) protected against the ADR-induced increase and decrease of MDA and GSH, respectively. The exact mechanism of action is not known, however, the inhibition of ADR-induced clastogenicity and lipid peroxidation by metformin may be attributed to the antioxidant action of the latter. Our results demonstrate that metformin might be useful to avert secondary tumor risk by decreasing the accumulation of free radicals and inhibition of mutagenicity.
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Affiliation(s)
- A M Aleisa
- Department of Pharmacology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
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1483
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Rosa RM, Moura DJ, Melecchi MIS, dos Santos RS, Richter MF, Camarão EB, Henriques JAP, de Paula Ramos ALL, Saffi J. Protective effects of Hibiscus tiliaceus L. methanolic extract to V79 cells against cytotoxicity and genotoxicity induced by hydrogen peroxide and tert-butyl-hydroperoxide. Toxicol In Vitro 2007; 21:1442-52. [PMID: 17683899 DOI: 10.1016/j.tiv.2007.06.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 06/06/2007] [Accepted: 06/07/2007] [Indexed: 10/23/2022]
Abstract
Plants of the genus Hibiscus thrives produce a diversity of molecules with bioactive properties. In a previous study of Hibiscus tiliaceus L. methanolic extract (HME) using bacteria and yeast, as test media, it has been shown that HME strongly inhibited the mutagenic action of H(2)O(2) or tert-butyl-hydroperoxide (t-BHP). Here, our interest is to evaluate the genotoxicity and the antigenotoxic/antimutagenic properties of HME using oxidative challenge with H(2)O(2) and t-BHP in V79 cells. We determined cytotoxicity using clonal survival assay; evaluated DNA damage using the comet assay and the micronucleus test in binucleated cells besides of the lipid peroxidation degree and the reduced glutathione content. We examined the ability of HME in quenching hydroxyl radical by means of a HPLC-based method utilizing the hypoxanthine/xanthine oxidase assay. At concentrations ranging from 0.001 to 0.1mg/mL, HME was not cytotoxic, genotoxic or mutagenic. Treatment with non-cytotoxic concentrations of HME increased cell survival after H(2)O(2) and t-BHP exposure and prevented DNA damage. The pre-treatment with HME also was able to decrease the mutagenic effect of these genotoxins, evaluated using the micronucleus test. HME prevented the increase in lipid peroxidation and decrease in GSH content in response to the oxidative challenge. Therefore, the ability in preventing against H(2)O(2)- and t-BHP-induced GSH depletion and lipid peroxidation was probably a major contribution to the cytoprotective effects. Moreover, HME acts as a hydroxyl radical scavenger. In summary, HME did not have a harmful or inhibitory effect on the growth of V79 cells and presented antioxidant activity, consequently, both antigenotoxic and antimutagenic effects against oxidative DNA damage.
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Affiliation(s)
- Renato Moreira Rosa
- Departamento de Biofísica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
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1484
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Sedelnikova OA, Nakamura A, Kovalchuk O, Koturbash I, Mitchell SA, Marino SA, Brenner DJ, Bonner WM. DNA double-strand breaks form in bystander cells after microbeam irradiation of three-dimensional human tissue models. Cancer Res 2007; 67:4295-302. [PMID: 17483342 DOI: 10.1158/0008-5472.can-06-4442] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The "radiation-induced bystander effect," in which irradiated cells can induce genomic instability in unirradiated neighboring cells, has important implications for cancer radiotherapy and diagnostic radiology as well as for human health in general. Although the mechanisms of this effect remain to be elucidated, we reported previously that DNA double-strand breaks (DSBs), directly measured by gamma-H2AX focus formation assay, are induced in bystander cultured cells. To overcome the deficiencies of cultured cell studies, we examined alpha-particle microbeam irradiation-induced bystander effects in human tissue models, which preserve the three-dimensional geometric arrangement and communication of cells present in tissues in vivo. In marked contrast to DNA DSB dynamics in irradiated cells, in which maximal DSB formation is seen 30 min after irradiation, the incidence of DSBs in bystander cells reached a maximum by 12 to 48 h after irradiation, gradually decreasing over the 7-day time course. At the maxima, 40% to 60% of bystander cells were affected, a 4- to 6-fold increase over controls. These increases in bystander DSB formation were followed by increased levels of apoptosis and micronucleus formation, by loss of nuclear DNA methylation, and by an increased fraction of senescent cells. These findings show the involvement of DNA DSBs in tissue bystander responses and support the notion that bystander DNA DSBs are precursors to widespread downstream effects in human tissues. Bystander cells exhibiting postirradiation signs of genomic instability may be more prone than unaffected cells to become cancerous. Thus, this study points to the importance of considering the indirect biological effects of radiation in cancer risk assessment.
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Affiliation(s)
- Olga A Sedelnikova
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA.
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1485
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Qiu L, Leng S, Wang Z, Dai Y, Zheng Y, Wang Z. Path Analysis of Biomarkers of Exposure and Early Biological Effects among Coke-Oven Workers Exposed to Polycyclic Aromatic Hydrocarbons. Cancer Epidemiol Biomarkers Prev 2007; 16:1193-9. [PMID: 17548684 DOI: 10.1158/1055-9965.epi-07-0001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Many host factors or biomarkers are involved in the process of early DNA damage induced by occupational exposure to polycyclic aromatic hydrocarbons (PAH) as seen in coke-oven workers. This paper aimed to identify complicated causal interrelationship of various biomarkers using the path analysis. In this analysis, we included 235 subjects (166 coke-oven workers and 69 nonexposed controls) whose data on the comet assay (e.g., Olive tail moment) and cytogenetic analysis of peripheral blood lymphocytes as well as urinary 1-hydroxypyrene (1-OHP) were available. The path analysis showed that coke-oven exposure and tobacco smoke were both significant predictors of the concentrations of urinary 1-OHP (P < 0.05), with a coefficient of determination of 0.75. The factors having significant influence on the Olive tail moment were in the following order: urinary 1-OHP > XRCC1-exon 9 variant genotype > ERCC2-exon 10 variant genotype > XRCC1-exon 6 variant genotype, with a coefficient of determination of 0.22. The variables of relative importance in influencing on cytokinesis-block micronucleus frequencies were in the following order: coke-oven exposure > urinary 1-OHP > age > mEH3 variant genotype > ERCC2-exon 10 variant genotype > XRCC1-exon 6 variant genotype, with a coefficient of determination of 0.27. These results indicated that exogenous agents, especially the coke-oven exposure, played a more important role than the genotypes in the induction of early genetic damage. In conclusion, the path analysis seemed to be an alternative statistical approach for the ascertainment of complicated association among related biomarkers for the assessment of occupational exposure.
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Affiliation(s)
- Li Qiu
- Department of Epidemiology and Health Statistics, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan, PR China
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1486
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Rossi D, Aiello V, Mazzoni L, Sensi A, Calzolari E. In vitro short-term test evaluation of catecholestrogens genotoxicity. J Steroid Biochem Mol Biol 2007; 105:98-105. [PMID: 17590328 DOI: 10.1016/j.jsbmb.2006.11.022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Accepted: 11/22/2006] [Indexed: 11/22/2022]
Abstract
Estrogens are indicated as being the most important etiological factors for the development and progression of breast cancer. The implication of estrogen in breast cancer has been associated mostly with the estrogen receptors that mediate cell proliferation. Evidence also exists to support the hypothesis of a direct role of estrogens as tumor initiators. However, the role of estrogen genotoxicity in breast cancer is still questionable. In this study the genotoxic activity of catecholestrogens and 16alpha-hydroxy estrone has been investigated by performing Salmonella strain TA98 and TA100 Ames tests, sister chromatide exchange assays (SCE) and micronucleus assays on human peripheral lymphocytes (CBMN and ARA/CBMN). We found a lack of positive results with micronucleus assays, except for 2-hydroxy estradiol (2-OHE(2)), which shows a peculiar "bell shaped" trend of micronucleus number versus concentrations. SCE assay suggests weak genotoxic activity of all tested catechol metabolites, except 4-hydroxy estrone (4-OHE(1)), which also showed negative results by ARA/CBMN. In this open debate, our results support the hypothesis of a weak genotoxicity, not correlated with the carcinogenetic potential of estrogens.
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Affiliation(s)
- Damiano Rossi
- CAT Group, Centro Analisi Territoriali, via Provinciale 73, I 44030 Copparo (Ferrara), Italy.
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1487
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Diaz D, Scott A, Carmichael P, Shi W, Costales C. Evaluation of an automated in vitro micronucleus assay in CHO-K1 cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2007; 630:1-13. [PMID: 17446119 DOI: 10.1016/j.mrgentox.2007.02.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Revised: 02/07/2007] [Accepted: 02/08/2007] [Indexed: 10/23/2022]
Abstract
In this paper, we describe the evaluation of an automated in vitro micronucleus assay using CHO-K1 cells in 96-well plates. CHO-K1 cells were pre-loaded with a cell dye that stains the cytoplasm, after which the cells were treated with the test compounds for either 3h (for the +S9 condition) or 24h (for the -S9 condition). A total of 10 concentrations were tested, of which the top five concentrations were scored (limited by either cytotoxicity or solubility). At the end of the incubation period the cells were fixed and their DNA was stained with Hoechst. The visualization and scoring of the cells was done using an automated fluorescent microscope coupled with proprietary automated image analysis software provided by Cellomics (Pittsburg, PA). A total of 46 compounds were used in this evaluation, including 8 aneugens and 25 clastogens with varied mechanisms of action. Thirteen non-genotoxic compounds were also included. The automated scoring had a sensitivity of 88% and a specificity of 100%, with a predictive value positive of 100% and a predictive value negative of 76%, compared to data from the literature that was obtained with manual scoring. We also describe the incorporation of a metabolic activation system using rat liver S9 homogenates, and the use of cell number counts as a cytotoxicity index which is complementary to the CBPI- (cytokinesis-block proliferation index) based index. Finally, we also discuss the potential for artefactual findings due to fluorescent precipitate, which should be carefully monitored to prevent false positive results. In conclusion, the automated in vitro micronucleus scoring is a valid alternative to the manual scoring of slides, and it has the advantage of generating data in a rapid and consistent manner, and with low compound requirements, which makes it well suited as a screening assay in the early stages of compound development.
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Affiliation(s)
- Dolores Diaz
- Cerep, Inc., 15318 NE 95th Street, Redmond, WA 98052, USA.
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1488
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Kim BM, Choi JY, Kim YJ, Woo HD, Chung HW. Reoxygenation following hypoxia activates DNA-damage checkpoint signaling pathways that suppress cell-cycle progression in cultured human lymphocytes. FEBS Lett 2007; 581:3005-12. [PMID: 17544403 DOI: 10.1016/j.febslet.2007.05.053] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2007] [Revised: 05/11/2007] [Accepted: 05/20/2007] [Indexed: 11/18/2022]
Abstract
Cellular responses to DNA damage after hypoxia and reoxygenation (H/R) were examined in human lymphocytes. Cultured lymphocytes exposed to H/R showed a lower cytokinesis block proliferation index and a higher frequency of micronuclei in comparison to control cells. Western blots showed that H/R exposure induced p53 expression; however, p21 and Bax expression did not increase, indicating that H/R did not affect p53 transactivational activity. Phosphorylation of p53 (Ser15), Chk1 (Ser345), and Chk2 (Thr68) was also observed, suggesting that H/R activates p53 through checkpoint signals. In addition, H/R exposure caused the phosphorylation and negative regulation of Cdc2 and Cdc25C, proteins that are involved in cell-cycle arrest at the G2/M checkpoint. The S-phase checkpoint, regulated by the ATM-p95/NBS1-SMC1 pathway, was also triggered in H/R-exposed lymphocytes. These results demonstrate that H/R exposure triggers checkpoint signaling and induces cell-cycle arrest in cultured human lymphocytes.
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Affiliation(s)
- Byeong-Mo Kim
- School of Public Health and Institute of Health and Environment, Seoul National University, Seoul, Republic of Korea
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1489
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Doak SH, Jenkins GJS, Johnson GE, Quick E, Parry EM, Parry JM. Mechanistic influences for mutation induction curves after exposure to DNA-reactive carcinogens. Cancer Res 2007; 67:3904-11. [PMID: 17440105 DOI: 10.1158/0008-5472.can-06-4061] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A mechanistic understanding of carcinogenic genotoxicity is necessary to determine consequences of chemical exposure on human populations and improve health risk assessments. Currently, linear dose-responses are assumed for DNA reactive compounds, ignoring cytoprotective processes that may limit permanent damage. To investigate the biological significance of low-dose exposures, human lymphoblastoid cells were treated with alkylating agents that have different mechanisms of action and DNA targets: methylmethane sulfonate (MMS), methylnitrosourea (MNU), ethylmethane sulfonate (EMS), and ethylnitrosourea (ENU). Chromosomal damage and point mutations were quantified with the micronucleus and hypoxanthine phosphoribosyltransferase forward mutation assays. MNU and ENU showed linear dose-responses, whereas MMS and EMS had nonlinear curves containing a range of nonmutagenic low doses. The lowest observed effect level for induction of chromosomal aberrations was 0.85 microg/mL MMS and 1.40 microg/mL EMS; point mutations required 1.25 microg/mL MMS and 1.40 microg/mL EMS before a mutagenic effect was detected. This nonlinearity could be due to homeostatic maintenance by DNA repair, which is efficient at low doses of compounds that primarily alkylate N(7)-G and rarely attack O atoms. A pragmatic threshold for carcinogenicity may therefore exist for such genotoxins.
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Affiliation(s)
- Shareen H Doak
- School of Medicine, University of Wales Swansea, Singleton Park, Swansea, Wales, United Kingdom.
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1490
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Brink A, Schulz B, Stopper H, Lutz WK. Biological significance of DNA adducts investigated by simultaneous analysis of different endpoints of genotoxicity in L5178Y mouse lymphoma cells treated with methyl methanesulfonate. Mutat Res 2007; 625:94-101. [PMID: 17586535 DOI: 10.1016/j.mrfmmm.2007.05.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2007] [Revised: 05/04/2007] [Accepted: 05/15/2007] [Indexed: 10/23/2022]
Abstract
The biological significance of DNA adducts is under continuous discussion because analytical developments allow determination of adducts at ever lower levels. Central questions refer to the biological consequences of adducts and to the relationship between background DNA damage and exposure-related increments. These questions were addressed by measuring the two DNA adducts 7-methylguanine (7-mG) and O(6)-methyl-2'-deoxyguanosine (O(6)-mdGuo) by LC-MS/MS in parallel to two biological endpoints of genotoxicity (comet assay and in vitro micronucleus test), using large batches of L5178Y mouse lymphoma cells treated with methyl methanesulfonate (MMS). The background level of 7-mG was 1440 adducts per 10(9) nucleotides while O(6)-mdGuo was almost 50-fold lower (32 adducts per 10(9) nucleotides). In the comet assay and the micronucleus test, background was in the usual range seen with smaller batches of cells (2.1% Tail DNA and 12 micronuclei-containing cells per 1000 binucleated cells, respectively). For the comparison of the four endpoints for dose-related increments above background in the low-response region we assumed linearity at low dose and used the concept of the "doubling dose", i.e., we estimated the concentration of MMS necessary to double the background measures. Doubling doses of 4.3 and 8.7microM MMS were deduced for 7-mG and O(6)-mdGuo, respectively. For doubling the background measures in the comet assay and the micronucleus test, 5 to 15-fold higher concentrations of MMS were necessary (45 and 66microM, respectively). This means that the contribution of an increase in DNA methylation to biological endpoints of genotoxicity is overestimated. For xenobiotics that generate adducts without background, the difference is even more pronounced because the dose-response curve starts at zero and the limit of detection of an increase is not affected by background variation. Consequences for the question of thresholds in dose-response relationships and for the setting of tolerable exposure levels are discussed.
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Affiliation(s)
- Andreas Brink
- Department of Toxicology, University of Würzburg, Versbacher Str. 9, 97078 Würzburg, Germany
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1491
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Kao GD, Jiang Z, Fernandes AM, Gupta AK, Maity A. Inhibition of phosphatidylinositol-3-OH kinase/Akt signaling impairs DNA repair in glioblastoma cells following ionizing radiation. J Biol Chem 2007; 282:21206-12. [PMID: 17513297 PMCID: PMC3614065 DOI: 10.1074/jbc.m703042200] [Citation(s) in RCA: 175] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Radiation therapy is a mainstay in the treatment of glioblastomas, but these tumors are often associated with radioresistance. Activation of the phosphatidylinositol-3-OH kinase (PI3K)/Akt pathway, which occurs frequently in glioblastomas due to inactivation of the tumor suppressor phosphatase and tensin homologue (PTEN), correlates with radioresistance. To directly test the link between Akt activation and radioresistance, we utilized PTEN-deficient U251 glioblastoma cells engineered to inducibly restore PTEN upon exposure to doxycycline. These cells showed high basal levels of Akt activation (i.e. high levels of phospho-Akt), but induction of PTEN led to substantially decreased phospho-Akt and was associated with radiosensitization. To investigate whether the PTEN-induced radiosensitization was attributable to impaired sensing versus repair of DNA damage, we assessed levels of gamma-H2AX after ionizing radiation in U251 cells induced for PTEN. Initial post-radiation levels of gamma-H2AX foci were not decreased in PTEN-induced cells; however, the resolution of these foci was significantly delayed. In contrast to these results, induction of phosphatase-dead PTEN showed no appreciable effect. Finally, exposure of cells to the PI3K inhibitor LY294002 did not decrease the occurrence of gamma-H2AX foci after irradiation but did markedly delay their resolution. These results together support a direct link between Akt activation, repair of DNA damage, and radioresistance in glioblastoma. Targeting the PI3K/Akt pathway may modulate DNA repair to improve the efficacy of radiation therapy.
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Affiliation(s)
| | | | | | | | - Amit Maity
- To whom correspondence should be addressed: 195 John Morgan Bldg., University of Pennsylvania School of Medicine, 3620 Hamilton Walk, Philadelphia, PA 19104. Tel.: 215-614-0078; Fax: 215-898-0090;
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1492
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Shuga J, Zhang J, Samson LD, Lodish HF, Griffith LG. In vitro erythropoiesis from bone marrow-derived progenitors provides a physiological assay for toxic and mutagenic compounds. Proc Natl Acad Sci U S A 2007; 104:8737-42. [PMID: 17502613 PMCID: PMC1885572 DOI: 10.1073/pnas.0701829104] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The goal of this study was to create an in vitro cell culture system that captures essential features of the in vivo erythroid micronucleus (MN) genotoxicity assay, thus enabling increased throughput and controlled studies of the hematopoietic DNA damage response. We show that adult bone marrow (BM) cultures respond to erythropoietin, the principal hormone that stimulates erythropoiesis, with physiological erythropoietic proliferation, differentiation, and enucleation. We then show that this in vitro erythropoietic system clearly signals exposure to genotoxicants through erythroid MN formation. Furthermore, we determined that DNA repair-deficient (MGMT(-/-)) BM displayed sensitivity to genotoxic exposure in vivo compared with WT BM and that this phenotypic response was reflected in erythropoietic cultures. These findings suggest that this in vitro erythroid MN assay is capable of screening for genotoxicity on BM in a physiologically reflective manner. Finally, responses to genotoxicants during erythroid differentiation varied with exposure time, demonstrating that this system can be used to study the effect of DNA damage at specific developmental stages.
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Affiliation(s)
- J. Shuga
- Department of Chemical Engineering
- Whitehead Institute for Biomedical Research
- Center for Environmental Health Sciences
| | - J. Zhang
- Whitehead Institute for Biomedical Research
| | - L. D. Samson
- Center for Environmental Health Sciences
- Biological Engineering Division
- Department of Biology, and
| | - H. F. Lodish
- Whitehead Institute for Biomedical Research
- Biological Engineering Division
- Department of Biology, and
- To whom correspondence should be addressed at:
Nine Cambridge Center, WI-601, Cambridge, MA 02141. E-mail:
| | - L. G. Griffith
- Center for Environmental Health Sciences
- Biological Engineering Division
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
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1493
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Lou J, He J, Zheng W, Jin L, Chen Z, Chen S, Lin Y, Xu S. Investigating the genetic instability in the peripheral lymphocytes of 36 untreated lung cancer patients with comet assay and micronucleus assay. Mutat Res 2007; 617:104-10. [PMID: 17303195 DOI: 10.1016/j.mrfmmm.2007.01.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 01/08/2007] [Accepted: 01/12/2007] [Indexed: 05/14/2023]
Abstract
The aim of present investigation was to study the genetic instability in peripheral lymphocytes of lung cancer patients. The micronucleus (MN) assay and comet assay were simultaneously used to detect the spontaneous genetic change and ionizing irradiation (IR) induced genetic damage in peripheral lymphocytes from 36 lung cancer patients and 30 controls. In MN assay, the results of both two indicators, micronucleated cell frequency (MCF) and micronucleus frequency (MNF), indicated that the average values of MCF, MNF and IR-induced MCF, MNF of lung cancer patients were 9.25+/-0.58, 10.17+/-0.72, 66.14+/-2.07 and 75.64+/-2.34 per thousand, respectively, which were significantly higher than those (6.10+/-0.65, 6.60+/-0.74, 60.50+/-1.71 and 67.60+/-2.13 per thousand) of controls (P<0.05 or 0.01). In comet assay, the results of mean tail moment (MTM) and IR-MTM showed 0.84+/-0.07 and 1.09+/-0.11, respectively, which were significantly higher than those (0.60+/-0.05 and 0.70+/-0.10) of controls (P<0.05). However, the difference between lung cancer group and control group for the mean tail length (MTL) and IR-MTL was not significant (P>0.05). The results of present investigation indicated that the genetic instability in peripheral lymphocytes of 36 lung cancer patients was significantly higher than that of controls.
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Affiliation(s)
- Jianlin Lou
- Zhejiang University, Medical College, Institute of Environmental Medicine, Hangzhou 310058, Zhejiang, People's Republic of China
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1494
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Rosa RM, do Nascimento Picada J, Saffi J, Henriques JAP. Cytotoxic, genotoxic, and mutagenic effects of diphenyl diselenide in Chinese hamster lung fibroblasts. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2007; 628:87-98. [PMID: 17223377 DOI: 10.1016/j.mrgentox.2006.12.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 12/04/2006] [Accepted: 12/07/2006] [Indexed: 11/26/2022]
Abstract
Diphenyl diselenide (DPDS) is an electrophilic reagent used in the synthesis of a variety of pharmacologically active organic selenium compounds, and may increase the risk of human exposure to this chemical at the workplace. In a previous study, we demonstrated the pro-oxidant action and the mutagenic properties of this compound on bacteria and yeast. In the present study, we evaluated the putative cytotoxic, pro-oxidant, genotoxic, and mutagenic properties of this molecule in V79 Chinese lung fibroblast cells. When cells were treated with increasing concentrations of DPDS, its cytotoxic activity, as determined using four cell viability endpoints, occurs in doses up to 50 microM. The MTT reduction was stimulated, which may indicate reactive oxygen species (ROS) generation. Accordingly, the treatment of cells for 3h with cytotoxic doses of DPDS increased TBARS levels, and sensitized cells to oxidative challenge, indicating a pro-oxidant effect. The measurement of total, reduced, and oxidized glutathione showed that DPDS can lead to lower intracellular glutathione depletion, with no increase in the oxidation rate in a dose- and time-dependent manner. At the higher doses, DPDS generates DNA strand breaks, as observed using the comet assay. The treatment also induced an increase in the number of binucleated cells in the micronucleus test, showing mutagenic risk by this molecule at high concentrations. Finally, pre-incubation with N-acetylcysteine, which restored GSH to normal levels, annulled DPDS pro-oxidant and genotoxic effects. These findings show that DPDS-induced oxidative stress and toxicity are closely related to intracellular level of reduced glutathione. Moreover, at lower doses, this molecule has antioxidant properties, protecting the cell against oxidative damage induced by hydrogen peroxide.
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Affiliation(s)
- Renato Moreira Rosa
- Departamento de Biofísica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
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1495
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Meaburn KJ, Cabuy E, Bonne G, Levy N, Morris GE, Novelli G, Kill IR, Bridger JM. Primary laminopathy fibroblasts display altered genome organization and apoptosis. Aging Cell 2007; 6:139-53. [PMID: 17274801 DOI: 10.1111/j.1474-9726.2007.00270.x] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
A number of diseases associated with specific tissue degeneration and premature aging have mutations in the nuclear envelope proteins A-type lamins or emerin. Those diseases with A-type lamin mutation are inclusively termed laminopathies. Due to various hypothetical roles of nuclear envelope proteins in genome function we investigated whether alterations to normal genomic behaviour are apparent in cells with mutations in A-type lamins and emerin. Even though the distributions of these proteins in proliferating laminopathy fibroblasts appear normal, there is abnormal nuclear positioning of both chromosome 18 and 13 territories, from the nuclear periphery to the interior. This genomic organization mimics that found in normal nonproliferating quiescent or senescent cells. This finding is supported by distributions of modified pRb in the laminopathy cells. All laminopathy cell lines tested and an X-linked Emery-Dreifuss muscular dystrophy cell line also demonstrate increased incidences of apoptosis. The most extreme cases of apoptosis occur in cells derived from diseases with mutations in the tail region of the LMNA gene, such as Dunningan-type familial partial lipodystrophy and mandibuloacral dysplasia, and this correlates with a significant level of micronucleation in these cells.
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Affiliation(s)
- Karen J Meaburn
- Laboratory of Nuclear and Genomic Health, Division of Biosciences, School of Health Sciences and Social Care, Brunel University, Uxbridge, Middlesex UB8 3PH, UK
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1496
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Zeni O, Gallerano GP, Perrotta A, Romanò M, Sannino A, Sarti M, D'Arienzo M, Doria A, Giovenale E, Lai A, Messina G, Scarfì MR. Cytogenetic observations in human peripheral blood leukocytes following in vitro exposure to THz radiation: a pilot study. HEALTH PHYSICS 2007; 92:349-57. [PMID: 17351499 DOI: 10.1097/01.hp.0000251248.23991.35] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Emerging technologies are considering the possible use of Terahertz radiation in different fields ranging from telecommunications to biology and biomedicine. The study of the potential effects of Terahertz radiation on biological systems is therefore an important issue in order to safely develop a variety of applications. This paper describes a pilot study devoted to determine if Terahertz radiation could induce genotoxic effects in human peripheral blood leukocytes. For this purpose, human whole blood samples from healthy donors were exposed for 20 min to Terahertz radiation. Since, to our knowledge, this is the first study devoted to the evaluation of possible genotoxic effects of such radiation, different electromagnetic conditions were considered. In particular, the frequencies of 120 and 130 GHz were chosen: the first one was tested at a specific absorption rate (SAR) of 0.4 mW g-1, while the second one was tested at SAR levels of 0.24, 1.4, and 2 mW g-1. Chromosomal damage was evaluated by means of the cytokinesis block micronucleus technique, which also gives information on cell cycle kinetics. Moreover, human whole blood samples exposed to 130 GHz at SAR levels of 1.4 and 2 mW g-1 were also tested for primary DNA damage by applying the alkaline comet assay immediately after exposure. The results obtained indicate that THz exposure, in the explored electromagnetic conditions, is not able to induce either genotoxicity or alteration of cell cycle kinetics in human blood cells from healthy subjects.
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Affiliation(s)
- O Zeni
- Interuniversity Center on Interaction Between Electromagnetic Fields and Biosystems (ICEmB) at CNR-IREA, Via Diocleziano 328-80124 Napoli, Italy.
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1497
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Dorn SB, Degen GH, Müller T, Bonacker D, Joosten HFP, van der Louw J, van Acker FAA, Bolt HM. Proposed criteria for specific and non-specific chromosomal genotoxicity based on hydrophobic interactions. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2007; 628:67-75. [PMID: 17292661 DOI: 10.1016/j.mrgentox.2006.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2006] [Revised: 11/20/2006] [Accepted: 11/27/2006] [Indexed: 10/23/2022]
Abstract
Tests for chromosomal damage are indispensable in the genotoxicity testing battery. Thus, positive results of clastogenicity or aneugenicity tests are of key relevance in safety assessment and product development. Schultz and Onfelt [N. Schultz, A. Onfelt, Sensitivity of cytokinesis to hydrophobic interactions. Chemical induction of bi- and multi-nucleated cells, Chem. Biol. Interact. 126 (2000) 97-123.] have studied the chemical induction of bi- and multi-nucleated cells in Chinese hamster V79 cells and compared non-specific agents with inducers acting through a known specific mechanism. They separated compounds with a specific action from those with a non-specific action based on lipophilicity, following a theory of hydrophobic interactions with processes of cytokinesis. It appeared possible to broaden the original database of this concept to include aneugenic as well as clastogenic compounds studied in the micronucleus (MN) test. The datasets used for this purpose were (A) the original dataset of Schultz and Onfelt [N. Schultz, A. Onfelt, Sensitivity of cytokinesis to hydrophobic interactions. Chemical induction of bi- and multi-nucleated cells, Chem. Biol. Interact. 126 (2000) 97-123.], and two sets (B, C) of our own data from studies in V79 cells in vitro. As the particular endpoints used were different (A: counts of bi- and multi-nucleated cells, B/C: micronucleus counts) the coherence of the experimental data sets was validated by including compounds belonging to both collections. Data set B included compounds with a specific effect on the mitotic spindle (nitrobenzene and benzonitrile) and data set C included the phytoestrogens genistein and daidzein, as well as a number of hormonal steroids with unknown mode of action. Taking all three data sets (A, B, C) together, the 33 compounds investigated covered a total lipophilicity range of logP between -0.51 (diamide) and 5.65 (17alpha-propylmesterolone). In order to separate statistical outliers (with a specific mode of action to be likely) from the large cluster of compounds with non-specific genotoxicity related to hydrophobic interactions, the method of robust regression was applied. It appeared that all compounds with a specific mode of action were in fact outliers of the lipophilicity rule. Genistein, a weak clastogen causing chromosomal aberrations and being discussed to induce topoisomerase-2 mediated DNA breaks, came close to the statistical borderline between compounds with specific and non-specific chromosomal genotoxicity. A general procedure is proposed, applicable in chemical product development, to screen specific and non-specific modes of action.
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Affiliation(s)
- Susanne B Dorn
- Institut für Arbeitsphysiologie an der Universität Dortmund, Ardeystr. 67, D-44139 Dortmund, Germany
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1498
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Lindberg HK, Wang X, Järventaus H, Falck GCM, Norppa H, Fenech M. Origin of nuclear buds and micronuclei in normal and folate-deprived human lymphocytes. Mutat Res 2007; 617:33-45. [PMID: 17250856 DOI: 10.1016/j.mrfmmm.2006.12.002] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 11/30/2006] [Accepted: 12/06/2006] [Indexed: 05/13/2023]
Abstract
Micronuclei are formed from chromosomes and chromosomal fragments that lag behind in anaphase and are left outside daughter nuclei in telophase. They may also be derived from broken anaphase bridges. Nuclear buds, micronucleus-like bodies attached to the nucleus by a thin nucleoplasmic connection, have been proposed to be generated similarly to micronuclei during nuclear division or in S-phase as a stage in the extrusion of extra DNA, possibly giving rise to micronuclei. To better understand these phenomena, we have characterized the contents of 894 nuclear buds and 1392 micronuclei in normal and folate-deprived 9-day cultures of human lymphocytes using fluorescence in situ hybridization with pancentromeric and pantelomeric DNA probes. Such information has not earlier been available for human primary cells. Surprisingly, there appears to be no previous data on the occurrence of telomeres in micronuclei (or buds) of normal human cells in general. Our results suggest that nuclear buds and micronuclei have partly different mechanistic origin. Interstitial DNA without centromere or telomere label was clearly more prevalent in nuclear buds (43%) than in micronuclei (13%). DNA with only telomere label or with both centromere and telomere label was more frequent in micronuclei (62% and 22%, respectively) than in nuclear buds (44% and 10%, respectively). Folate deprivation especially increased the frequency of nuclear buds and micronuclei harboring telomeric DNA and nuclear buds harboring interstitial DNA but also buds and micronuclei with both centromeric and telomeric DNA. According to the model we propose, that micronuclei in binucleate lymphocytes primarily derive from lagging chromosomes and terminal acentric fragments during mitosis. Most nuclear buds, however, are suggested to originate from interstitial or terminal acentric fragments, possibly representing nuclear membrane entrapment of DNA that has been left in cytoplasm after nuclear division or excess DNA that is being extruded from the nucleus.
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Affiliation(s)
- Hanna K Lindberg
- New Technologies and Risks, Work Environment Development, Finnish Institute of Occupational Health, Topeliuksenkatu 41aA, FI-00250 Helsinki, Finland
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1499
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Colognato R, Coppedè F, Ponti J, Sabbioni E, Migliore L. Genotoxicity induced by arsenic compounds in peripheral human lymphocytes analysed by cytokinesis-block micronucleus assay. Mutagenesis 2007; 22:255-61. [PMID: 17369186 DOI: 10.1093/mutage/gem010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This work focuses on the analysis of genotoxic effects on human peripheral lymphocytes exposed in vitro to different arsenic (As) compounds by means of the cytokinesis-block micronucleus assay. The study was carried out by challenging peripheral human lymphocytes with six As compounds in trivalent or pentavalent forms such as arsenite (As(III)) and arsenate (As(V)) and organoarsenic species such as monomethylarsonous acid (MMAs(III)), monomethylarsonic acid (MMAs(V)), dimethylarsinic acid (DMAs(V)) and trymethylarsine oxide (TMAO(V)). For As(III) and As(V) at concentrations of 4 and 32 microM, respectively, an increase of micronuclei (MN) frequency was found. MMAs(III) and MMAs(V) induced a statistically significant increase of MN frequency at the dose of 2 and 500 microM, respectively. For DMAs(V), no significant increase of MN was observed, although a decrease of the nuclear division index (NDI) was evident, indicating a cytotoxic effect. The genotoxic mechanism of action of MMAs(III) was further evaluated by means of fluorescence in situ hybridization analysis. Due to a higher percentage of centromere-positive MN, MMAs(III) showed a clear aneuploidogenic property. Finally, for TMAO(V) no genotoxicity was observed up to 1 mM. These results show how speciation is important in determining the genotoxic and cytotoxic effects of As compounds in human peripheral lymphocytes and support the emerging hypothesis that the induction of aneuploidy could be a mechanism by which As exerts its carcinogenic properties.
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Affiliation(s)
- R Colognato
- Department of Human and Environmental Sciences, University of Pisa, Via S. Giuseppe 22, 56126 Pisa, Italy
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1500
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Wang JJ, Sanderson BJS, Wang H. Cytotoxicity and genotoxicity of ultrafine crystalline SiO2 particulate in cultured human lymphoblastoid cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2007; 48:151-7. [PMID: 17285640 DOI: 10.1002/em.20287] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Respirable crystalline silica has been classified as a human lung carcinogen. Ultrafine (diameter < 100 nm) silica particles may be important in carcinogenesis, although the mechanisms remain unclear. In the present study, WIL2-NS cells were incubated for 6, 24, and 48 hr with 0, 30, 60, and 120 microg/ml ultrafine crystalline SiO(2) (UF-SiO(2)). The cytotoxic and genotoxic effects caused by UF-SiO(2) in cultured human cells were investigated via a set of bioassays. Significant dose- dependent decreases in percent cell viability were seen with increasing dose of UF-SiO(2) in the methyl tetrazolium assay. Significant decreases were seen at 120 microg/ml (58, 38, and 57% for 6, 24, and 48-hr exposure, respectively). During 4 days growth in the flasks, there was a slight recovery observed after washing off UF-SiO(2) as measured by the population growth assay. Significant dose-dependent reduction in the cytokinesis block proliferation index was observed by the cytokinesis block micronucleus assay. Treatment with 120 microg/ml UF-SiO(2) for 24 hr produced a fourfold increase in the frequency of micronucleated binucleated cells (MNBNC). The increase in MNBNC was dose-dependent. The lowest dose that gave a statistically significant increase in MNBNC was 30 microg/ml (24-hr treatment), which had cytotoxicity of less than 10%. There was no significant difference in DNA strand breakage as measured by the Comet assay. A significant increase in induced mutant frequency was found at 120 microg/ml as detected by the hypoxanthine guanine phosphoribosyltransferase mutation assay. The results indicate that UF-SiO(2) is cytotoxic and genotoxic in cultured human cells.
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Affiliation(s)
- Jing J Wang
- Department of Public Health, University of Adelaide, South Australia 5005, Australia.
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