Furazolidone induced oxidative DNA damage via up-regulating ROS that caused cell cycle arrest in human hepatoma G2 cells

Furazolidone (FZD) is an antimicrobial agent that has been shown to have mutagenic, genotoxic and potentially carcinogenic properties when tested in a variety of systems in vitro and in vivo. In this study, we investigated FZD's DNA damaging effect in human hepatoma cells aiming at further defining the molecular mechanism of FZD's cytotoxicity. Addition of FZD resulted in cell growth suppression and cell cycle arrest in S phase accompanied by remarkable DNA strand breaks with increased levels of intracellular reactive oxygen species (ROS) and 8-hydroxydeoxyguanosine. Activities of antioxidases were down-regulated following FZD treatment and antioxidant agent catalase and superoxide dismutase ameliorated FZD's DNA damaging effects. Moreover, FZD caused much more extensive damage to mitochondrial DNA (mtDNA) than to nuclear DNA for which the decrease in mtDNA content correlated with FZD usage in a dose-dependent manner. However, there was no evidence of FZD induced mtDNA mutation in the mitochondrial DNA displacement loop. These results demonstrate that FZD up-regulates the production of intracellular ROS to cause oxidative DNA damage with mtDNA being the most vulnerable targets. Oxidative stress and the injury of mtDNA could be early indicators of FZD-induced cytotoxicity, with the resulting abnormal progression of the cell cycle.     

DNA damage and alterations in expression of DNA damage responsive genes induced by TiO2 nanoparticles in human hepatoma HepG2 cells

Abstract

We investigated the genotoxic responses to two types of TiO₂ nanoparticles (<25 nm anatase: TiO₂-An, and <100 nm rutile: TiO₂-Ru) in human hepatoma HepG2 cells. Under the applied exposure conditions the particles were agglomerated or aggregated with the size of agglomerates and aggregates in the micrometer range, and were not cytotoxic. TiO₂-An, but not TiO₂-Ru, caused a persistent increase in DNA strand breaks (comet assay) and oxidized purines (Fpg-comet). TiO₂-An was a stronger inducer of intracellular reactive oxygen species (ROS) than TiO₂-Ru. Both types of TiO₂ nanoparticles transiently upregulated mRNA expression of p53 and its downstream regulated DNA damage responsive genes (mdm2, gadd45α, p21), providing additional evidence that TiO₂ nanoparticles are genotoxic. The observed differences in responses of HepG2 cells to exposure to anatase and rutile TiO₂ nanoparticles support the evidence that the toxic potential of TiO₂ nanoparticles varies not only with particle size but also with crystalline structure.     

阿莫西林对人HepG2细胞DNA有短暂损伤作用

目的 为了探讨阿莫西林对人HepG2细胞DNA是否有损伤作用.方法 培养的人HepG2细胞经不同浓度(2、10、50和250μmol/L)阿莫西林处理1h或经50μmol/L阿莫西林处理不同时间(20、40、60、120和180min)后,运用单细胞凝胶电泳(SCGE)技术结合彗星图像软件(CASP)分析细胞尾部DNA百分率(tail DNA%)变化情况.结果 不同浓度阿莫西林处理后结果显示,HepG2细胞尾部DNA百分率明显升高,至50μmol/L阿莫西林时达到最高值,各浓度处理组与不处理对照组相比差异皆有显著性(P<0.01);而同一浓度(50μmol/L)阿莫西林处理不同时间后结果显示,HepG2细胞尾部DNA百分率逐渐升高,至1h处理时间点时达到最高值,其后随着处理时间延长HepG2细胞尾部DNA百分率逐渐降低.结论 阿莫西林对人HepG2细胞DNA有短暂损伤作用,阿莫西林诱发的HepG2细胞DNA损伤可能随时间延长逐渐被HepG2细胞本身修复除去.     

Protective effects of curcumin on methylglyoxal-induced oxidative DNA damage and cell injury in human mononuclear cells

AIM: To examine the effect of curcumin on oxidative DNA damage and cell apoptosis and injury caused by the reaction of methylglyoxal(MG) with amino acids. METHODS: We used DNA strand breaks to examine the effect of curcumin on oxidative DNA damage. In addition, reactive oxygen species(ROS) formation occurs in MG-treated mononuclear cells, so the effect of curcumin on ROS generation was measured using 2',7'-dichlorofluorescin diacetate(DCF-DA) as the detection reagent. Moreover, the impact effects of curcumin on MG-induced cell apoptosis and ROS injury were analyzed by TUNEL and ELISA assay. The collagen I attachment ability of mononuclear cells was examined by trypan blue staining. RESULTS: Our results revealed that curcumin prevented MG/lysine-induced oxidative stress and DNA damage. Curcumin also inhibited MG-induced apoptosis and generation of ROS in mononuclear cells. MG-treated mononuclear cells displayed a lower degree of attachment to collagen (the major component of the vessel wall subendo-thelium), whereas cells pretreated with curcumin before MG treatment exhibited restored affinities for collagen. CONCLUSION: These results demonstrated that oxidative stress plays a role in MG-induced cell injury and alterations in attachment ability, and that curcumin blocks these effects by virtue of its antioxidant properties.     

线粒体DNA氧化损伤热点的形成及其修复速率的比较

本研究旨在探讨线粒体DNA氧化损伤热点的形成是否与该点DNA修复速率慢有关 .BRL 3A细胞暴露于 5 0mmol·L- 1过氧化氢 (H2 O2 ) 30min后 ,分别于 0 ,1,4及 2 4h收获细胞 ,应用连接介导聚合酶链反应分析线粒体DNA氧化损伤热点的修复百分率并与线粒体DNA氧化损伤的总修复百分率比较 ,通过狭缝印迹法 ,比较了各时间点细胞内p5 3/线粒体DNA比率来验证其修复的可靠性 .结果表明 :在 4及2 4h ,热点的修复速率分别为 5 .2 %和 4 2 .1% .而线粒体DNA的总修复百分率分别为 76 .9%和 84 .1% ,后者与前者相比 ,其修复速率快 1～ 14倍左右 .应用狭缝印迹发现各时间点细胞内p5 3/线粒体DNA比率无明显变化 .因此 ,线粒体DNA氧化损伤热点的形成与其修复速率较慢有关 .狭缝印迹结果表明所观测的线粒体DNA的修复是可信的     

Relationship between reactive oxygen species and sodium-selenite-induced DNA damage in HepG2 cells

Selenium compounds, as an effective chemopreventive agent, can induce apoptosis in tumor cells. Reactive oxygen species (ROS) are important mediators in apoptosis induced by various stimuli, which include chemopreventive agents. In this study, we investigated the relationship between ROS and the levels of DNA damage induced by selenite in HepG2 cells. After HepG2 cells were treated with selenite, there was a dose-dependent decrease in cell viability. The levels of ROS induced by selenite were measured by 2′, 7′-dichlorofluorescein diacetate (DCFH-DA) fluorescence, which shos a dose-and time-dependent increase in HepG2 cells. The levels of DNA damage in HepG2 increased in all cells treated with an increasing dose of selenite at 0, 2.5, 5, 10, and 20 μmol/L. N-acetylcysteine (NAC), a known antioxidant, increased cell viability and decreased ROS generation. Moreover, NAC effectively blocked DNA damage induced by selenite. These results revealed that ROS might play an important role in selenite-induced DNA damage that can be reduced by NAC treatment.     

Cytotoxicity and oxidative DNA damage by nanoparticles in human intestinal Caco-2 cells

Abstract

The use of engineered nanoparticles in the food sector is anticipated to increase dramatically, whereas their potential hazards for the gastrointestinal tract are still largely unknown. We investigated the cytotoxic and DNA-damaging effects of several types of nanoparticles and fine particles relevant as food additives (TiO₂ and SiO₂) or for food packaging (ZnO and MgO) as well as carbon black on human intestinal Caco-2 cells. All particles, except for MgO, were cytotoxic (LDH and WST-1 assay). ZnO, and to lesser extent SiO₂, induced significant DNA damage (Fpg-comet), while SiO₂ and carbon black were the most potent in causing glutathione depletion. DNA damage by TiO₂ was found to depend on sample processing conditions. Interestingly, application of different TiO₂ and ZnO particles revealed no relation between particle surface area and DNA damage. Our results indicate a potential hazard of several food-related nanoparticles which necessitate investigations on the actual exposure in humans.     

Assessment of DNA damage,cytotoxicity, and apoptosis in human hepatoma (HepG2) cells after flurochloridone herbicide exposure

In vitro effects of flurochloridone (FLC) and its formulations Twin Pack Gold® [25% active ingredient (a.i.)] and Rainbow® (25% a.i.) were evaluated in HepG2 cells. Whereas cytokinesis-blocked micronucleus cytome (CBMN-cyt) and single-cell gel electrophoresis (SCGE) assays were employed for genotoxicity, MTT, neutral red, and apoptosis detections were used for cytotoxicity evaluation. Activities were tested within the concentration range of 0.25–15 μg/ml FLC. Results demonstrated that neither FLC nor Rainbow® was able to induce MNs. On the other hand, 5 μg/ml Twin Pack Gold® only increased MN frequency. Furthermore, 10 and 15 μg/ml of both formulations resulted in cellular cytotoxicity demonstrated by alterations in the nuclear division index and cellular death. A marked increase in the genetic damage index was observed after treatment with all compounds. SCGE assay appeared to be more sensitive bioassay for detecting primary DNA strand breaks at lower concentrations of FLC than did MN. Our results reveal that FLC and its two formulations trigger apoptosis on HepG2 cells. The results represent the first experimental evidence of the in vitro apoptogenic role exerted on mammalian cells by FLC and the FLC-based formulations Rainbow® and Twin Pack Gold®, at least on HepG2 cells.     

大黄素诱导人肝癌HepG2细胞线粒体凋亡作用研究

目的 研究大黄素对人肝癌HepG2细胞线粒体凋亡的影响。方法 培养人肝癌HepG2细胞,与5、10、20、40、60、80、100 μmol/L的大黄素作用24、48 h,MTS法检测细胞增殖;40、80、160 μmol/L大黄素作用HepG2细胞24 h,AO/EB双荧光染色法观察细胞凋亡的形态学改变;Annexin V/PI染色经流式细胞仪检测细胞凋亡;分光光度法检测caspase 3活性;ATP试剂盒检测细胞ATP含量,不同荧光探针加载后流式细胞仪测定大黄素对HepG2细胞内活性氧（ROS）含量、Ca²⁺浓度、线粒体膜电位（MMP）变化的影响。结果 大黄素抑制HepG2细胞生长,且呈时间、浓度相关性,半数抑制浓度（IC₅₀）为（77.42±1.25）μmol/L;随着大黄素浓度升高,AO/EB双染观察到细胞核浓缩、碎裂、凋亡小体等凋亡形态;与对照组比较,大黄素40、80、160 μmol/L作用于HepG2细胞24 h后细胞凋亡率显著增加,caspase 3活性显著增强,ROS水平、Ca²⁺浓度明显增加（P<0.05、0.01、0.001）,80、160 μmol/L组线粒体膜电位明显降低,ATP含量显著下降（P<0.05、0.01、0.001）。结论 大黄素造成HepG2细胞内ROS堆积,ATP合成功能障碍,线粒体膜电位明显下降,进而诱导线粒体通透转运孔开放,导致钙离子和细胞色素C外流,活化caspase蛋白家族,导致细胞凋亡。     

Genotoxicity of acrylamide in human hepatoma G2 (HepG2) cells

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.     

Malathion‐induced oxidative stress,cytotoxicity, and genotoxicity in human liver carcinoma (HepG2) cells

Malathion is an organophosphate pesticide that is known for its high toxicity to insects and low to moderate potency to humans and other mammals. Its toxicity has been associated with the inhibition of acetylcholinesterase activity, leading to the interference with the transmission of nerve impulse, accumulation of acetylcholine at synaptic junctions, and subsequent induction of adverse health effects including headache, dizziness, nausea, vomiting, bradycardia, and miosis. Oxidative stress (OS) has been reported as a possible mechanism of malathion toxicity in humans. Hence, the aim of this study was to examine the role of OS in malathion‐induced cytotoxicity and genotoxicity. To achieve this goal, MTT, lipid peroxidation, and single cell gel electrophoresis (Comet) assays were performed, respectively, to evaluate the levels of cell viability, malondialdehyde (MDA) production, and DNA damage in human liver carcinoma (HepG₂) cells. Study results indicated that malathion is mitogenic at lower levels of exposure, and cytotoxic at higher levels of exposure. Upon 48 h of exposure, the average percentages of cell viability were 100% ± 11%, 117% ± 15%, 86% ± 15%, 35% ± 9%, and 27% ± 7% for 0, 6, 12, 18, and 24 mM, respectively. In the lipid peroxidation assay, the concentrations of MDA produced were 12.55 ± 0.16, 20.65 ± 0.27, 31.1 ± 0.40, 34.75 ± 0.45, and 15.1 ± 0.20 μM in 0, 6, 12, 18, and 24 mM malathion, respectively. The Comet assay showed a significant increase in DNA damage at the 24 mM malathion exposure. Taken together, our results indicate that malathion exposure at higher concentrations induces cytotoxic and genotoxic effects in HepG₂ cells, and its toxicity may be mediated through OS as evidenced by a significant production of MDA, an end product of lipid peroxidation. © 2009 Wiley Periodicals, Inc. Environ Toxicol 2010.     

Cytotoxic effects of procyanidins from Castanea mollissima Bl. shell on human hepatoma G2 cells in vitro

Significant cytotoxic effects of procynadins from chestnut (Castanea mollissima Bl.) shell (CSPC) on human hepatoma G2 (HepG2) cells were found in vitro. CSPC could inbibit HepG2 proliferation in a dose-dependent manner (100–400 μg/mL), arrest cell cycle in the G₀/G₁ phase, induce apoptosis and trigger necrosis of HepG2. Proapoptotic effect of CSPC was evidenced by nuclear condensation, internucleosomal DNA fragmentation. Treatment of HepG2 cells with CSPC caused a loss of mitochondrial membrane potential and stimulated reactive oxidative species (ROS) generation. These results suggested CSPC could trigger apoptosis and necrotic cell death in HepG2 cell, which might be associated with ROS generation through the mitochondria-dependent signaling way.     

姜黄素对肝癌HepG2和Bel-7404细胞增殖的抑制作用

目的研究姜黄素对人肝癌HepG2和Bel-7404细胞增殖的影响。方法不同浓度的姜黄素(2.5,10.0,25.0,50.0,100.0μg/mL),0.2%二甲基亚砜的RPMI 1640培养基加细胞为空白对照,2μg/mL顺铂为阳性对照。MTT法检测肝癌HepG2和Bel-7404细胞的增殖。结果姜黄素对肝癌细胞HepG2和Bel-7404的增殖抑制有量效关系,并呈时间依赖性。在相同作用时间下,姜黄素组、顺铂组对肝癌细胞HepG2和Bel-7404增殖有明显的抑制作用,与空白对照组比较均有显著性差异(P<0.05)。与空白对照组比较,2.5,10.0μg/mL姜黄素对肝癌细胞HepG2和Bel-7404的增殖没有明显的抑制作用(P>0.05),而25.0,50.0,100.0μg/mL姜黄素以及顺铂组对肝癌细胞HepG2和Bel-7404的增殖均有明显的抑制作用(P<0.05)。结论姜黄素可以明显的抑制肝癌细胞HepG2和Bel-7404的生长,且存在剂量-时间的关系。     

福莫司汀对培养的HL60细胞DNA的损伤

福莫司汀对培养的ＨＬ６０细胞ＤＮＡ的损伤寿江１，冯杏婉（北京药理毒理研究所，北京１００８５０，中国）１ＮｏｗｉｎＤｅｐａｒｔｍｅｎｔｏｆＴｏｘｉｃｏｌｏｇｙ，ＩｎｓｔｉｔｕｔｅｏｆＲａｄｉａｔｉｏｎＭｅｄｉｃｉｎｅ，Ｂｅｉｊｉｎｇ１００８５０，Ｃｈｉ...     

A comparative study of chemically induced DNA damage in isolated human and rat testicular cells

Testicular cells prepared from human organ transplant donors or from Wistar rats were used to compare 15 known reproductive toxicants with respect to their ability to induce DNA damage, measured as single-strand DNA breaks and alkali labile sites (ssDNA breaks) with alkaline filter elution. The compounds tested included various categories of chemicals (i.e., pesticides, industrial chemicals, cytostatics, and mycotoxins) most of which are directly acting genotoxicants (i.e., reacting with DNA either spontaneously or via metabolic activation). In addition, a few indirect genotoxic and nongenotoxic reproductive toxicants were included. Six of the chemicals induced no significant levels of ssDNA breaks in human and rat testicular cells: methoxychlor (10 to 100 μM, human and rat), benomyl (10 to 100 μM, human and rat), thiotepa (10 to 1000 μM, human and rat), cisplatin (30 to 1000 μM, human; 100 to 1000 μM, rat), Cd²⁺ (30 to 1000 μM, human; 100 to 1000 μM, rat), and acrylonitrile (30 to 1000 μM, human; 30 to 300 μM, rat). Four chemicals induced significant levels of ssDNA breaks in testicular cells from both species: styrene oxide (≥ 100 μM, rat and human), 1,2-dibromoethane (EDB) (≥ 100 μM, rat; 1000 μM human), thiram (≥ 30 μM, rat; ≥ 100 μM, human), and chlordecone (300 μM, rat; ≥ 300 μM, human). Finally, five chemicals induced ssDNA breaks in one of the two species. Four chemicals induced significant ssDNA breaks in rat testicular cells only: 1,2-dibromo-3-chloropropane (DBCP) (≥ 10 μM), 1,3-dinitrobenzene (1,3-DNB) (≥ 300 μM), Cr⁶⁺ (1000 μM), and aflatoxin B₁ (≥ 100 μM), the last two of these produced only a minor positive response. One chemical, acrylamide, induced a marginal increase in ssDNA breaks in human at 1000 μM, but not in rat testicular cells. Although based on a limited number of donors, the data indicate a close correlation between the induction of DNA damage in human and rat testicular cells in vitro. For some chemicals, however, there appears to be differences in the susceptibility to chemically induced ssDNA breaks of isolated testicular cells from the two species. The data indicate that the parallel use of human and rat testicular cells provides a valuable tool in the assessment of human testicular toxicity.     

姜黄素对长波紫外线所致DNA损伤的拮抗作用

目的　观察长波紫外线引起人表皮样癌细胞 DNA链断裂损伤的情况 ,以及姜黄素对这种损伤的拮抗作用。方法　用长波紫外线照射细胞 ,用单细胞凝胶电泳法检测 DNA损伤。结果　长波紫外线剂量依赖性地诱发表皮细胞的 DNA链断裂损伤 ,损伤的高峰出现在照射后 1h。而姜黄素可以拮抗长波紫外线引起的DNA链断裂 ,表现为彗星细胞百分比的降低和彗星尾巴长度的缩短 ,并有量效关系。结论　姜黄素可以预防长波紫外线照射引起的皮肤细胞 DNA链断裂损伤。     

亚硝胺化合物对人源肝癌细胞HepG2的DNA损伤风险评价

目的 使用人肝癌HepG2细胞筛选亚硝胺的体外彗星试验的S9 mix配方，并对17种常见的亚硝胺化合物开展彗星试验，研究其DNA亲和力和碱基嵌入风险。方法 在非S9活化和S9活化条件下对HepG2细胞进行N-二甲基亚硝胺（NDMA）、N-二乙基亚硝胺（NDEA）、N-亚硝基二丁胺（NDBA）、N-亚硝基二异丙胺（NDIPA）、N-亚硝基-N-甲基-4-氨基丁酸（NMBA）、N-亚硝基甲乙胺（NMEA）、N-亚硝基-N-乙基异丙胺（NEIPA）、N-亚硝基二丙胺（NDPA）、N-甲基-N-亚硝基苯胺（NMPA）、亚硝基二苯胺（NDPh）、二乙醇亚硝胺（NDELA）、亚硝基吗啉（NMOR）、亚硝基-N-甲基-N-（2-苯基）乙胺（NMPEA）、亚硝基吡咯烷（NPYR）、亚硝基哌啶（NPIP）、4-甲基亚硝胺基-1-3-吡啶基-1-丁酮（NNK）、N-亚硝基降烟碱（NNN）给药处理，2种条件均设置溶媒对照（0.5% DMSO）、3个浓度梯度的给药组和阳性对照组，在非S9活化条件下以甲基磺酸甲酯（MMS）为阳性对照，S9活化条件下以环磷酰胺（CP）为阳性对照。以NDMA和NDEA为例比较3种S9 mix配方对亚硝胺化合物体外DNA亲和力和DNA损伤风险，选择效果最优者开展剩余化合物在S9条件下的彗星试验，计算各组尾DNA含量百分率（% tail DNA）的平均值和中位数。结果 在非S9代谢活化条件下17种常见亚硝胺化合物均未导致HepG2细胞核DNA明显损伤。S9 mix配方C中S9体积分数仅为3.36%，但对亚硝胺化合物的代谢活化效果最佳。在该条件下，除NDPh外，其余亚硝胺化合物均对HepG2细胞存在DNA的损伤作用。烷基类亚硝胺化合物对DNA损伤作用强弱顺序依次为NDMA>NEIPA>NDPA>NMEA>NDEA>NDBA>NDIPA，与化合物α氢的数目基本呈正相关。含苯基的亚硝胺化合物对DNA损伤作用强弱顺序依次为NMPEA>NMPA>NDPh，而环状亚硝胺化合物对DNA损伤作用强弱顺序为NMOR>NPIP≈NPYR。结论 提供最新的亚硝胺化合物体外DNA损伤风险数据，并提出适宜亚硝胺化合物的体外彗星试验S9 mix配方，为亚硝胺化合物的毒性评价提供手段。     

Microcystin-LR induces oxidative DNA damage in human hepatoma cell line HepG2.

Microcystins are naturally occurring hepatotoxins produced by strains of Microcystis aeruginosa. They are involved in promoting primary liver tumours and a previous study showed that they might also be tumour initiators. In this study we demonstrate that microcystin-LR (MCLR) at doses that were not cytotoxic (0.01-1 microg/ml), induced dose and time dependent DNA strand breaks in human hepatoma cell line HepG2. These DNA strand breaks were transient, reaching a maximum level after 4h of exposure and declining with further exposure. In the presence of the DNA repair inhibitors cytosine arabinoside (AraC) and hydroxyurea (HU), together with MCLR, DNA strand breaks accumulated after prolonged exposure. These results suggest that DNA strand breaks are intermediates, produced during the cellular repair of MCLR induced DNA damage. Digestion of DNA with purified, oxidative DNA damage specific enyzmes, endonuclease III (Endo III) and formamidopyrimidine-DNA glycosylase (Fpg) markedly increased DNA strand breaks in MCLR treated cells, providing evidence that a substantial portion of the MCLR induced DNA strand breaks originate from excision of oxidative DNA adducts. A hydroxyl radical scavenger (DMSO) significantly reduced MCLR induced DNA damage. From these results we conclude that MCLR induces formation of reactive oxygen species that cause DNA damage, and that MCLR may act as an initiator of liver cancer.     

Involvement of oxidative stress in methyl parathion and parathion‐induced toxicity and genotoxicity to human liver carcinoma (HepG2) cells

Methyl parathion (C₈H₁₀NO₅PS) and parathion (C₁₀H₁₄NO₅PS) are both organophosphate insecticides (OPI) widely used for household and agricultural applications. They are known for their ability to irreversibly inhibit acetylcholinesterase which often leads to a profound effect on the nervous system of exposed organisms. Many recently published studies have indicated that human exposure to OPI may be associated with neurologic, hematopoietic, cardiovascular, and reproductive adverse effects. Studies have also linked OPI exposure to a number of degenerative diseases including Parkinson's, Alzheimer's, and amyotrophic lateral sclerosis. Also, oxidative stress (OS) has been reported as a possible mechanism of OPI toxicity in humans. Hence, the aim of the present investigation was to use human liver carcinoma (HepG₂) cells as a test model to evaluate the role of OS in methyl parathion‐ and parathion‐induced toxicity. To achieve this goal, we performed the MTT [3‐(4, 5‐dimethylthiazol‐2‐yl)‐2, 5‐diphenyltetrazolium bromide] assay for cell viability, lipid peroxidation assay for malondialdehyde (MDA) production, and Comet assay for DNA damage, respectively. Results from MTT assay indicated that methyl parathion and parathion gradually reduce the viability of HepG₂ cells in a dose‐dependent manner, showing 48 h‐LD₅₀ values of 26.20 mM and 23.58 mM, respectively. Lipid peroxidation assay resulted in a significant increase (P < 0.05) of MDA level in methyl parathion‐ and parathion‐treated HepG₂ cells compared with controls, suggesting that OS plays a key role in OPI‐induced toxicity. Comet assay indicated a significant increase in genotoxicity at higher concentrations of OPI exposure. Overall, we found that methyl‐parathion is slightly less toxic than parathion to HepG₂ cells. The cytotoxic effect of these OPI was found to be associated, at least in part, with oxidative cell/tissue damage. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2013.     

WRN基因在氢醌致U937细胞DNA损伤中的作用

目的 WRN基因在氢醌(HQ)致U937细胞DNA损伤中的作用.方法 常规培养白血病细胞U937至生长对数期,低剂量HQ组、中剂量HQ组、高剂量HQ组分别以10、20、40μmol/L HQ染毒24 h及48 h,以等体积的完全培养基培养的细胞组为完全空白对照组.采用单细胞凝胶电泳(SCGE)检测细胞DNA损伤;采用免疫印迹法检测WRN蛋白的相对表达量.结果 (1)HQ可导致细胞DNA损伤,且损伤效用随染毒浓度增加而增大,48 h比24 h的DNA损伤程度增加,呈时间—剂量依赖性(P＜0.05);(2)免疫印迹结果显示,HQ染毒24 h,WRN蛋白相对表达量在各组差异无统计学意义(P＞0.05);HQ染毒48 h高剂量组分别与空白组、低剂量、中剂量中比较,WRN蛋白相对表达量呈降低的趋势(P＜0.05).结论 HQ诱导WRN蛋白表达下调影响U937细胞DNA损伤修复.