The effect of various antioxidants and other modifying agents on oxygen-radical-generated DNA damage in human lymphocytes in the COMET assay

Anderson, Diana; Yu, Tianwei; Phillips, Barry; Schmezer, Peter

doi:10.1016/0027-5107(94)90300-x

Cited by 571 publications

(267 citation statements)

References 18 publications

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“…Comet Assay for Detecting DNA Strand Breaks-The comet assay, also called the single-cell gel electrophoresis, was performed as described previously (34). In brief, fully frosted microscopic slides were covered with 110 l of 0.5% normal melting agarose at 60°C.…”

Section: Methodsmentioning

confidence: 99%

5-Aza-2′-deoxycytidine Activates the p53/p21Waf1/Cip1 Pathway to Inhibit Cell Proliferation

Zhu

Hileman

et al. 2004

Journal of Biological Chemistry

143

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In addition to its demethylating function, 5-aza-2-deoxycytidine (5-aza-CdR) also plays an important role in inducing cell cycle arrest, differentiation, and cell death. However, the mechanism by which 5-aza-CdR induces antineoplastic activity is not clear. In this study, we found that 5-aza-CdR at limited concentrations (0.01-5 M) induces inhibition of cell proliferation as well as increased p53/p21Waf1/Cip1 expression in A549 cells (wild-type p53) but not in H1299 (p53-null) and H719 cells (p53 mutant). The p53-dependent p21 As demethylating agents, 5-aza-cytidine and 5-aza-2Ј-deoxycytidine (5-aza-CdR) 1 have been extensively used for epigenetic research (1-4). Both demethylating agents are incorporated into DNA where they bind DNA methyltransferase (DNMT) in an irreversible, covalent manner, thus sequestering the enzyme and preventing maintenance of the methylation state (5-7). Consequently, silenced genes induced by hypermethylation are re-expressed after treatment with these demethylating agents.Originally, 5-aza-cytidine and 5-aza-CdR were developed as anticancer agents (5, 8) and have been shown to have significant cytotoxic and antineoplastic activities in many experimental tumors (9 -12). 5-Aza-CdR is reported to be noncarcinogenic and incorporates into DNA but not RNA or protein (13,14). 5-Aza-CdR has been found empirically to have more potent therapeutic effects than 5-aza-cytidine in cell culture and animal models of human cancers. However, 5-aza-CdR-induced cytotoxicity may not be linked to its demethylating function (3,(15)(16)(17). In addition, the therapeutic effects of 5-aza-CdR in the treatment of different human cancer cells are conflicting. 5-Aza-CdR appears to be beneficial in the treatment of human leukemias (9,18,19), myelodysplastic syndromes (20, 21), and hemoglobinopathies (22, 23). On the other hand, there has been less positive experience in the effectiveness of 5-aza-CdR for the treatment of human solid tumors (10, 24). Therefore, it is possible that one or more critical factors may be involved in regulating the cellular response to 5-aza-CdR treatment that vary in different cell types.p53 is a very important tumor suppressor gene and is reported to be abnormal in more than 50% of human cancers (25). Chemotherapeutic agents frequently act through the mechanism of DNA damage, and p53 plays an important role in the induction of cell cycle arrest and apoptosis in response to DNA damage (26). 5-Aza-CdR has also shown anticancer activity that may be related to its ability to induce DNA damage (15,27). Based on the scenario mentioned above, it is hypothesized that 5-aza-CdR may induce DNA damage, thereby activating p53, which in turn increases p21Waf1/Cip1 expression, leading to the inhibition of cell proliferation.To confirm the role of p53 in the 5-aza-CdR-induced inhibition of cell proliferation, human lung cancer cells with different p53 status were selected as the targets for this study. As an important downstream target of p53 activation, p21Waf1/Cip1 plays a critical role in inhibit...

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Section: Methodsmentioning

confidence: 99%

5-Aza-2′-deoxycytidine Activates the p53/p21Waf1/Cip1 Pathway to Inhibit Cell Proliferation

Zhu

Hileman

et al. 2004

Journal of Biological Chemistry

143

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“…Immediately after collection, the blood (~0.5 mL) was mixed in chilled phosphate buffer saline (Ca 2+ -Mg 2+ free). The viability of erythrocytes was evaluated by the trypan blue exclusion test method (Anderson et al, 1994) and cell samples showing cell viability higher than 84% were further processed for comet assay. In brief, about 15 µL of cell suspension (approx.…”

Section: Alkaline Single Cell Gel Electrophoresis (Scge) /Comet Assaymentioning

confidence: 99%

Evaluation of genotoxic and oxidative stress response to dimethoate in freshwater fish Channa punctatus (Bloch)

Ali

Kumar

et al. 2014

Chemical Speciation & Bioavailability

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Dimethoate is one of the organophosphate insecticides widely used in agriculture throughout the world and is an inhibitor of cholinesterase in animals. The objective of the present study was to detect oxidative stress and DNA damage induced by dimethoate in the freshwater fish Channa punctatus (C. punctatus). The LC 50 -96 h value of technical grade dimethoate was estimated at 19.10 µg L -1 in a semi-static system and, on the basis of the LC 50 value, three concentrations were determined. The fish were exposed to these concentrations of dimethoate for 96 h and samplings were done at 24 and 96 h for assessment of oxidative stress and DNA damage. After exposure to dimethoate, the level of superoxide dismutase declined while lipid peroxidation, glutathione, induction of micronucleus and DNA damage were increased in C. punctatus as the concentration and exposure time increased. Thus our results suggest that dimethoate induces genotoxic effects which invariably accompanied and correlated with oxidative stress.

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“…Una de las técnicas utilizada para esta vigilancia es el ensayo del cometa o la electroforesis alcalina de células individuales, que permite evaluar el daño causado en el material genético por diferentes agentes químicos y físicos (21)(22)(23). Tiene amplias aplicaciones en toxicología genética, en ensayos de genotoxicidad in vitro (24)(25)(26)(27)(28)(29) e in vivo (30)(31)(32), en vigilancia biológica ambiental y en vigilancia de poblaciones humanas expuestas a diversas sustancias químicas mutagénicas (33)(34)(35)(36)(37)(38)(39)(40).…”

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Evaluación del daño en el ADN y vigilancia biológica de la exposición laboral a solventes orgánicos, 2006

et al. 2008

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Introducción. La exposición a solventes es uno de los mayores riesgos potenciales para millones de trabajadores en el mundo; los solventes generan contaminación ambiental y desencadenan problemas de salud pública. Objetivo. Determinar los niveles de los metabolitos benceno, tolueno y xileno, los polimorfismos de las enzimas CYP2E1, GSTM1, GSTT1 y el daño del ADN mediante el ensayo del cometa. Materiales y métodos. Se llevó a cabo un estudio descriptivo de corte transversal para la determinación de polimorfismos genéticos y prueba del cometa en 90 trabajadores pertenecientes a cinco empresas. Se aplicó una encuesta, se tomaron muestras de sangre y de orina, se midieron las concentraciones de fenol, ácido hipúrico orto y meta-metilhipúrico. Se hizo el análisis estadístico y se exploraron posibles asociaciones. Resultados. El 34,4% eran trabajadores con exposición directa a solventes. En este grupo se evidenciaron concentraciones superiores a los límites permisibles en 3,3% para fenol, en 6,6% para ácido hipúrico, en 3,3% para ácido orto-metilhipúrico y en 36,7% para ácido metametilhipúrico, mayor longitud promedio de la cola del cometa (19,5 µm) y un incremento del porcentaje de células con daño medio (19,0%) (p=0,0007). El porcentaje de individuos expuestos con genotipos ausentes para las enzimas GSTT1 y GSTM1 fue de 46,7% y de 56,8%, respectivamente. Conclusión. El uso de biomarcadores de exposición, efecto y susceptibilidad, se ha convertido en una herramienta fundamental para la evaluación del riesgo asociado con la exposición a agentes tóxicos.Palabras clave: daño del ADN/genética, exposición profesional, solventes/toxicidad, salud pública DNA damage assessment and biological monitoring of occupational exposure to organic solvents, 2006Introduction. Exposure to solvents is one of the highest potential risks for millions of workers in the world; they can generate substantial environmental pollution leading to outbreaks of public health problems. Objective. Blood levels were determined for metabolites of benzene, toluene and xylene, and polymorphisms for enzymes CYP2E1, GSTM1, GSTT1 were characterized. Damage to DNA was assessed by the comet assay for exposure to organic solvents. Materials and methods. A cross-sectional study was undertaken in 90 employees from 5 different companies. A survey form was administered; blood was sampled to detect the genetic polymorphisms and to apply the comet assay (single cell gel electrophoresis) to detect DNA fragmentation. The concentrations of phenol, ortho and meta methylhippuric acids were measured in urine. Statistical analyses explored the possible associations. Results. The percentage of workers directly exposed to solvents was 34.4%. In this group, the evidence indicated concentrations higher than the permitted limits: 3.3% for phenol, 6.6% for

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The effect of various antioxidants and other modifying agents on oxygen-radical-generated DNA damage in human lymphocytes in the COMET assay

Cited by 571 publications

References 18 publications

5-Aza-2′-deoxycytidine Activates the p53/p21Waf1/Cip1 Pathway to Inhibit Cell Proliferation

5-Aza-2′-deoxycytidine Activates the p53/p21Waf1/Cip1 Pathway to Inhibit Cell Proliferation

Evaluation of genotoxic and oxidative stress response to dimethoate in freshwater fish Channa punctatus (Bloch)

Evaluación del daño en el ADN y vigilancia biológica de la exposición laboral a solventes orgánicos, 2006

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