OBJECTIVETo study the effect of polychlorinated biphenyl, Aroclor1254 on benzo (a) pyrene [B (a) P]-induced DNA damage in HepG2 cells.

METHODSHepG2 cells were pretreated with Aroclor1254 (11.5, 23 and 46 micromol/L) for 24 hours and then exposed to B (a) P (50 micromol/L). DMSO (10 ml/L) was used as solvent control. Single cell gel electrophoresis (SCGE) and high-performance liquid chromatography-electrochemical detection (HPLC-EC) assays were applied to detect DNA single-strand breaks and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in HepG2 cells, respectively.

RESULTSAverage Oliver tail moment (OTM) and 8-OHdG level in HepG2 cells were significantly increased in B (a) P treated group (1.66 +/- 0.21), (23.31 +/- 6.02) 8-OHdG/10(6)dG than that in solvent control (0.79 +/- 0.15), (12.31 +/- 3.24) 8-OHdG/10(6)dG, respectively. In Aroclor 1254 treated group (11.5, 23.0, 46.0 micromol/L), average OTM were 0.88 +/- 0.20, 1.01 +/- 0.15 and 1.10 +/- 0.16, and 8-OHdG levels were (19.57 +/- 7.57), (22.80 +/- 9.16) and (31.74 +/- 9.25) 8-OHdG/10(6)dG, respectively. A concentration of 46 micromol/L Aroclor1254 caused a significant increase of 8-OHdG level as compared with the solvent control. After pretreatment of HepG2 cells with Aroclor1254 (11.5, 23.0 and 46.0 micromol/L), B (a) P induced more DNA strand breaks (OTM: 2.14 +/- 0.22, 2.43 +/- 0.32 and 2.71 +/- 0.31) and 8-OHdG [(32.50 +/- 3.81), (49.23 +/- 16.66) and (60.36 +/- 18.04) 8-OHdG/10(6)dG] in HepG2 cells than B (a) P alone.

CONCLUSIONAroclor1254 might enhance B (a) P-induced DNA damage in HepG2 cells, which should imply a synergistic effect of Aroclor1254 on the genotoxicity of B (a) P.

Benzo(a)pyrene ; toxicity ; Cell Line, Tumor ; DNA Damage ; drug effects ; Drug Synergism ; Humans ; Polychlorinated Biphenyls ; toxicity

OBJECTIVETo study the characteristics of occupational exposure of polycyclic aromatic hydrocarbons (PAHs) in coke oven workers.

METHODSSamples were collected individually and PAHs concentration in the ambient air were assayed by high performance liquid chromatography (HPLC) and toxic equivalency factors (TEFs) were introduced to assess the carcinogenic potency.

RESULTSThe levels of PAHs occupational exposure in oven workers at topside was higher than at side oven and bottom oven (P < 0.05). Non-carcinogenic PAHs were more than 70% of total PAHs and benzo[a]pyrene accounted for 65.5% approximately 72.4% of total benzo[a]pyrene equivalents. Total occupational exposure level of PAHs in coke oven workers was positively related to the content of benzo[a]pyrene and pyrene, respectively (r(2) = 0.84, r(2) = 0.94, P < 0.05).

CONCLUSIONCoke oven workers were exposed to a high level of PAHs which possessed some extent of carcinogenic potency, and benzo[a]pyrene is the chief carcinogenic substance.

Benzo(a)pyrene ; analysis ; toxicity ; Carcinogens ; analysis ; toxicity ; Chromatography, High Pressure Liquid ; Coke ; Humans ; Occupational Exposure ; Polycyclic Compounds ; analysis ; toxicity

Animals ; Benzo(a)pyrene/toxicity* ; Cytokines ; Dibutyl Phthalate/toxicity* ; Female ; Liver ; Male ; NF-kappa B ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo understand benzo[a]pyrene (B[a]P) mediated cellular responses, and to provide clues to explore molecular mechanism of mutagenesis and carcinogenesis induced by B[a]P.

METHODSTwo-dimensional electrophoresis (2-DE) was used to investigate the protein expression levels of FL cells after B[a]P exposure, matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) combined with database search was applied to identify the differentially expressed proteins.

RESULTStatistical analysis showed that the volumes of 47 protein spots were altered after B[a]P treatment (P<0.05) and 23 proteins were successfully identified, including zinc finger proteins, SWI/SNF related protein, Bromo domain containing domain and other proteins.

CONCLUSIONThese affected proteins may be involved in the cellular responses to B[a]P exposure, and may mediate the B[a]P induced mutagenesis and carcinogenesis.

Amnion ; chemistry ; cytology ; drug effects ; Benzo(a)pyrene ; toxicity ; Cells, Cultured ; DNA Repair ; Electrophoresis, Gel, Two-Dimensional ; Humans ; Proteomics ; Zinc Fingers

OBJECTIVETo explore the effects of selenium on DNA damage induced by benzo[a] pyrene (BaP) in mouse lung cells.

METHODSSodium selenite was given to Kunming male mice by i.p. and BaP was given by oral gavage. The control group was given solvent only with the same method. DNA damage was detected by single cell gel electrophoresis (or comet assay).

RESULTSThe damage degrees in mice treated with 125, 250 and 500 mg/kg of BaP were more severe than that of control (P < 0.01). The rates of comet cells in the BaP-treated groups (43.50%, 84.00%, 95.63%) were significantly higher than that of control (9.75%, P < 0.01), and there was obvious dose-response relationship. 0.75, 1.50 and 3.00 mg/kg of sodium selenite presented antagonistic effects against DNA damage induced by 250 mg/kg of BaP in mouse's lung cells. The antagonistic effect of sodium selenite at the dose of 1.50 mg/kg was better than those of sodium selenite at the doses of 0.75, 3.00 mg/kg.

CONCLUSIONBaP at the doses of 125 approximately 500 mg/kg could significantly induce DNA damage of lung cells in mice. 0.75 approximately 3.00 mg/kg of sodium selenite could inhibit DNA damage of lung cells in mice induced by 250 mg/kg of BaP.

Animals ; Benzo(a)pyrene ; toxicity ; DNA Damage ; drug effects ; Lung ; cytology ; metabolism ; Male ; Mice ; Mice, Inbred Strains ; Selenium ; pharmacology

OBJECTIVETo explore the effects of DNA polymerase β expression level on the genotoxicity and genetic instability induced by benzo(a)pyrene (BaP),and provide experimental the basis for further study on the carcinogenic molecular mechanism of BaP.

METHODSThree kinds of cell lines with the identical genetic background, polβ wild-type cells (polβ+/+), polβ null cells (polβ-/-) and polβ overexpression cells (polβ oe) were applied as cellular models. The oxidative damage, genotoxicity and genetic instability induced by BaP were analyzed by using different methods respectively.

RESULTSCell viability and colony forming ability of 3 kinds of cell lines exposed to BaP decreased with BaP. After treated with 5 and 20 µmol/L concentration of BaP, fluorescence intensity of polβ-/- cell line was significantly higher than that of other two cell lines (P < 0.05). When treated with 5.00 µmol/L and 20.00 µmol/L concentration of BaP, the SOD activities (76.56 ± 2.84 and 62.78 ± 4.28 U/mg pro) of polβ-/- cell line were significantly lower than that (84.85 ± 3.59) of control group and those (85.21 ± 3.20 and 76.90 ± 3.38 U/mg pro) of polβ+/+ cell line. In 20.00 µmol/L BaP group. SOD activity (82.59 ± 4.64 U/mg pro) of polβ oe cell line was lower than that (88.58 ± 6.77 U/mg pro) of control but higher than that of polβ+/+ cell line (P < 0.05). In 1.25, 5.00 and 20.00 µmol/L concentration BaP groups, the micronucleus rates of polβ-/- cell line were much higher than those of polβ+/+ cell line (P < 0.05). In 5.00 and 20.00 µmol/L concentration BaP groups, the micronucleus rates of polβ oe cell line were significantly lower than those of polβ+/+ line (P < 0.05). In 5.00 and 20.00 µmol/L concentration BaP groups, HPRT gene mutation frequencies (26.16 × 10(-6) and 37.51 × 10(-6); 27.68 × 10(-6) and 38.63 × 10(-6)) in polβ-/- cells and polβ oe cells were significantly higher than those (19.76 × 10(-6) and 24.78 × 10(-6)) of polβ+/+ cells (P < 0.05).

CONCLUSIONPolβ could play a role in protecting the cells from the genotoxicity and genetic instability induced by BaP, and the normal expression level of polβ was indispensable for maintaining genome stability.

Animals ; Benzo(a)pyrene ; toxicity ; Cell Line ; DNA Damage ; DNA Polymerase beta ; metabolism ; Mice ; Micronucleus Tests ; Mutation Rate

OBJECTIVETo investigate cytotoxicity and genotoxicity of benzo(a)pyrene (B(a)P) by 16HBE-CYP1A1 cells which are human bronchial epithelial cell with CYP1A1 transformed.

METHODSExpression of CYP1A1 and mEH of cell models were tested by real-time quantitative polymerase chain reaction. Cells were treated with 0, 1, 5, 10 and 20 micromol/L B(a)P for 24 h. Adverse effects of B(a)P were tested by cytokinesis-block micronucleus (CBMN) cytome assays. Cytotoxicity was assessed by the nuclear division index (NDI), frequency of necrotic and apoptotic cells. Genetic damages were assessed by frequencies of CBMN, nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs).

RESULTSHigh levels of CYP1A1 and mEH were found in 16HBE-CYP1A1 cells (relative mRNA content was 7.8 x 10(-4) and 0.030 respectively). In 16HBE-CYP1A1 cells, NDI were decreased in 1, 5, 10 and 20 micromol/L B(a)P treated groups, 1.92 +/- 0.04, 1.71 +/- 0.01, 1.61 +/- 0.04, and 1.41 +/- 0.01, respectively; and lower than control group (2.08 +/- 0.03). Compared with control group ((82.67 +/- 6.66)%), the binucleated cells ratios were decreased, (76.33 +/- 3.51)%, (66.33 +/- 0.58)%, (51.67 +/- 1.53)% and (39.0 +/- 1.0)% respectively.Necrotic cells ratios were (1.93 +/- 0.42)%, (2.20 +/- 0.53)%, (8.07 +/- 0.90)% and (15.27 +/- 2.80)%, respectively, higher than control group ((0.47 +/- 0.11)%). The differences were significant (F values were 899.94, 303.33, 240.87, P < 0.01). Apoptotic cells were increased at lower groups and decreased to normal at higher groups treated by B(a)P. They were (1.20 +/- 0.53)%, (2.00 +/- 0.20)%, (1.47 +/- 0.12)%, (1.20 +/- 0.00)% and (1.20 +/- 0.00)%, respectively. Analysis on biomarkers of genetic damage, the significant dose-effect relationship were observed in NPBs and NBUDs (F values were 50.23, 121.09, P < 0.01, respectively). Frequencies of NPBs were (4.67 +/- 2.89) per thousand, (7.33 +/- 1.53) per thousand, (10.67 +/- 2.08) per thousand and (11.00 +/- 1.00) per thousand respectively. Frequencies of NBUDs were (2.33 +/- 0.58) per thousand, (4.00 +/- 1.00) per thousand, (5.00 +/- 1.00) per thousand, and (7.67 +/- 1.16) per thousand respectively. However, the dose-relationship of CBMN last only to 10 micromol/L B(a)P treated groups in 16HBE-CYP1A1 cells, and frequencies of CBMN were (8.33 +/- 3.21) per thousand, (14.67 +/- 1.15) per thousand, respectively. Frequency of CBMN was (16.67 +/- 2.88) per thousand in 20 micromol/L B(a)P treated group, lower than 10 micromol/L B(a)P treated group ((17.67 +/- 2.08) per thousand). In 16HBEV control cells, the cytotoxicity was found only in higher B(a)P treated groups and frequencies of CBMN, NPBs and NBUDs were increased also. While no significant differences were observed between 5, 10, 20 micromol/L B(a)P treated groups (they were (6.37 +/- 2.08) per thousand, (9.33 +/- 1.52) per thousand, (9.33 +/- 3.21) per thousand; (4.33 +/- 1.53) per thousand, (6.00 +/- 2.65) per thousand, (5.33 +/- 1.53) per thousand and (2.33 +/- 0.58) per thousand, (3.33 +/- 1.16) per thousand, (3.67 +/- 1.16) per thousand, respectively).

CONCLUSIONSThe genetic damages were more severe after treated with activated B(a)P, which may be induced by decreased NDI, increased necrotic cells and inhibition of apoptosis.

Apoptosis ; drug effects ; Benzo(a)pyrene ; toxicity ; Cell Division ; drug effects ; Cell Line, Transformed ; DNA Damage ; Humans ; Micronuclei, Chromosome-Defective

OBJECTIVETo investigate the sensitivity to bleomycin (BLM) in peripheral blood lymphocytes (PBL) among coke-oven workers.

METHODSNinty-four coke-oven workers with exposure to a high level of polycyclic aromatic hydrocarbons and 64 non-coke-oven workers (control) were recruited into this study. PBL was challenged by 8 microg/ml BLM, a known carcinogen, to induce certain amount of DNA damage, the difference of olive tail moment (TM) measured by comet assay before and after BLM treatment reflected the sensitivity towards mutagens.

RESULTSThe distribution of age, sex, and prevalence of smoking and drinking were not significantly different between these two groups. The geometric mean of urinary 1-hydroxypyrene (1-OHP) was significantly higher in coke-oven workers than in controls (9.0 versus 1.5 microg/L, t = -9.317, P < 0.01). The coke-oven workers showed significantly higher sensitivity to BLM than controls (17.7 versus 14.9, t = -2.583, P = 0.01). A large inter-group difference in sensitivity to BLM was observed in both controls and coke-oven workers. Stratification analysis revealed the significant association between high 1-OHP level (> 9.0 microg/L) and increased sensitivity to BLM (F = 4.001, P = 0.05) among coke-oven workers. Smoking subjects showed a significant higher value of sensitivity than nonsmokers in controls but not in coke-oven workers. No significant difference was observed between age, drinking status, coking history or external exposure class and BLM sensitivity.

CONCLUSIONExposure to coke oven emission could increase the sensitivity to mutagens, which might be a reason of high incidence of lung cancer among coke-oven workers.

Adult ; Benzo(a)pyrene ; toxicity ; Bleomycin ; toxicity ; Coke ; Comet Assay ; DNA Damage ; DNA Repair ; Female ; Humans ; Lymphocytes ; drug effects ; Male ; Middle Aged ; Mutagens ; toxicity ; Occupational Exposure

OBJECTIVETo study the influence of Benzo (a) pyrene on cell cycle distribution of quiescent diploid human embryonic lung fibroblast (HELF) cells.

METHODSHELF cells were synchronized at G0 phase of cell cycle by 0.5% serum starvation for 48 hours and identified by flow cytometry (FCM). Cells were treated with 20 micromol/L benzo (a) pyrene for 4 h and detected for the changes of cell cycle distribution 0 h, 24 h, 48 h after treatment respectively. HELF cells were treated with 0, 5, 10, 20 micromol/L Benzo (a) pyrene for 24 h and detected for cell cycle regulators p53, p21 and p16 expression changes using Western Blotting method. On the other hand, the dynamic changes of these regulators were also been detected within 24 h after 20 micromol/L Benzo (a) pyrene treated for 4h.

RESULTS0.5% Serum starvation for 48 hours could effectively synchronize HELF at G0 stage and G0 reached 78%. Well-modulated control cells entered into cell cycle to synthesize DNA and cells at S phase reached 43.9% 24 h after serum re-stimulate, while 20 micromol/L B (a) P treated cells were arrested in G1 stage. Control cells entered into the G1 stage of next cell cycle another 24 h later, B (a) P treated cells recovered from G1 arrest, 26.5% of which reached S phase, having a delay of almost 24 h compared with controls. After a series of B (a) P concentrations acting for 24 h, we found that P53 and P21 expression increased dramatically. On the other hand, P53 and P21 increased 4 h after treatment, P53 recovered to normal level after 12 h while P21 kept increasing in 24 h. P16 initially decreased and became normal at 24 h.

CONCLUSIONB (a) P induced quiescent HELF cells undergoing a reversible G1 arrest related with p53-p21 pathway.

Benzo(a)pyrene ; toxicity ; Carcinogens ; toxicity ; Cell Cycle ; drug effects ; Cells, Cultured ; Diploidy ; Fibroblasts ; cytology ; drug effects ; Flow Cytometry ; G1 Phase ; drug effects ; Humans ; Lung ; cytology ; embryology

OBJECTIVETo investigate the effect of benzo[a] pyrene(BaP) on DNA damage and expression of genes involved in nucleotide excision repair[xeroderma pigmentosum group B, C, G(XPB, XPC, XPG) and excision repair cross-complementing 1 (ERCC1)] in lung cancer A549 cells.

METHODSCell survival was measured using MIT metabolic viability assay. Single cell gel assay was applied to determine the DNA damage and repair. The level of gene expression was measured by reverse transcription-polymerase chain reaction.

RESULTSThe cell survival decreased from 95.0% to 70.0% after 24 h treatment with BaP of varying concentration ranging 0.625-20.000 mumol/L. The cell survival decreased to 87.0% and 73.0% respectively after 12 h and 24 h treatment with 10 mumol/L BaP, with DNA damage gradually elevated. At 12 h after 24 h treatment, the cell survival further decreased to 59.0% and DNA damage became most serious. At 24 h after 24 h treatment, cell survival recovered to 71.0%, and damaged DNA was repaired gradually. XPB and XPC gene expression increased to 4.5-fold and 11.2-fold respectively compared with basal level at 24 h treatment or 12 h after 24 h treatment with 10 mumol/L BaP respectively. However, ERCC1 and XPG gene expression was inhibited in 24 h treatment period, then recovered gradually after treatment.

CONCLUSIONBenzo[a]pyrene could lead to DNA damage and expression level change of genes involved in nucleotide excision repair in lung cancer A549 cells.

Benzo(a)pyrene ; toxicity ; Cell Line, Tumor ; Cell Survival ; DNA Damage ; DNA Repair ; DNA-Binding Proteins ; genetics ; Endonucleases ; genetics ; Humans ; Lung Neoplasms ; genetics