OBJECTIVETo investigate the effects of hydroquinone (HQ) on expression of Polymerase eta (Pol eta) and DNA damage in human hepatic cells (L-02), and to explore the role and possible mechanism of Pol eta involved in the process of DNA damage-tolerance.

METHODSAfter L-02 hepatic cells were exposed to HQ with various concentrations (0, 5, 10, 20, 40, 80 and 160 micromol/L) for 24 h, cell survival rate was detected by MTT assay; DNA impairment was detected by single cell gel electrophoresis (SCGE); Real-time fluorescent quantitative PCR and Western blotting methods were used to measure the expression of Pol eta at the mRNA and protein level in L-02 hepatic cells exposed to HQ with various concentrations (0, 5, 10, 20, 40, 80 and 160 micromol/L).

RESULTSMTT assay showed that HQ with concentrations from 0 to 80 micromol/L had little effect on the survival rate of L-02 (P>0.05); whereas the survival rate of the group of 160 micromol/Lwas significantly higher than that of the control (P<0.01) after being treated with HQ for 24 h; the higher dose of HQ presented, the more degrees of DNA damage were produced. It was found that HQ in a low concentration (1-80 micromol/L) could induce the expression of Pol eta which was in proportion to the increasements of HQ concentration; the expression levels of mRNA and protein were reached to the maximum when treated with 80 micromol/L; the expression of Pol eta decreased (the relative quantity values were 2.32 +/- 0.16 and 1.20 respectively) once the concentration of HQ exceeded 160 micromol/L as compared with the group of 80 micromol/L, but it was higher than that of the control.

CONCLUSIONThis study suggested that Pol eta might involve in the process of DNA damage-tolerance induced by HQ in the hepatic cells.

Cell Survival ; drug effects ; Cells, Cultured ; DNA Damage ; drug effects ; DNA Repair ; DNA-Directed DNA Polymerase ; metabolism ; Hepatocytes ; drug effects ; metabolism ; Humans ; Hydroquinones ; adverse effects ; Mutagens

OBJECTIVETo investigate the cyto-genotoxicity of cigarette smoke condensates (CSCs) in human peripheral blood lymphocytes with different assays in vitro.

METHODSHuman lymphocytes were exposed to particle matter of cigarette smoke combined with or without S9 mixtures at doses of 25, 50, 75, 100 and 125 microg/ml for 3 h. The cytotoxicity induced by CSCs was detected by CCK-8 assay. The DNA damage, DNA repair (repair time: 30, 60, 90, 120 and 240 min, respectively) and the somatic cell mutations induced by 75 microg/ml CSCs were measured by comet assay, hprt gene and TCR gene mutation tests, respectively.

RESULTSCCK-8 assay indicated that the cell viability decreased with CSCs doses. At the doses of 100, 125 microg/ml, the cell viability of CSCs +S9 group was significantly higher than that of CSCs -S9 group (P < 0.05, P < 0.01). In comet assay, DNA damage significantly increased in a dose-dependent manner, as compared with controls (P < 0.01). Moreover, there was significant difference between -S9 group and +S9 group (P < 0.05, P < 0.01). The Mf-TCR at each dose group was significantly higher than that of controls (P < 0.05, P < 0.01). The Mf-hprt at high-dose groups were significantly higher than that of controls (P < 0.01), and significant difference of Mf-TCR and Mf-hprt at high doses of CSCs between -S9 group and +S9 group (P < 0.05, P < 0.01). The DNA damage induced by CSCs +S9 or CSCs -S9 could be repaired, but DNA repair speed was different between -S9 group and +S9 group (P < 0.05, P < 0.01).

CONCLUSIONCSCs may induce cyto-genotoxicity in human peripheral blood lymphocytes in vitro, but S9 mix could reduce the toxicity of CSCs and impact DNA repair speed.

Cells, Cultured ; Comet Assay ; DNA Damage ; drug effects ; DNA Repair ; drug effects ; Humans ; Lymphocytes ; drug effects ; Male ; Mutation ; Tobacco Smoke Pollution ; adverse effects ; Young Adult

DNA Damage ; drug effects ; Formaldehyde ; toxicity ; Mutagenicity Tests

Chromium ; toxicity ; DNA Methylation ; drug effects ; Epigenesis, Genetic ; Humans

OBJECTIVESThis study was conducted to explore effects of selenium on rat hepatocellular DNA damage induced by cadmium in vitro.

METHODSodium selenite was added at concentrations of 8.75, 17.50 and 35.00 micromol/L respectively with cadmium chloride at the concentrations of 8.75, 17.50 and 35.00 micromol/L respectively and rat hepatocellular DNA damage was measured with single cell gel electrophoresis (comet assay).

RESULTSSodium selenite at the concentration of 8.75 micromol/L inhibited DNA damage caused by cadmium chloride at the concentration of 8.75, 17.50 and 35.00 micromol/L in rat liver cells (P < 0.05). Although sodium selenite at 17.50 micromol/L inhibited DNA damage induced by cadmium chloride at 17.50 and 35.00 micromol/L, it did not inhibit DNA damage induced by cadmium chloride at 8.75 micromol/L. Sodium selenite at 35.00 micromol/L did not have antagonistic effects on DNA damage induced by cadmium chloride at 8.75, 17.50 and 35.00 micromol/L. In addition, sodium selenite at 8.75 micromol/L had the best antagonistic effect while cadmium chloride at 8.75 micromol/L, but the antagonistic effect of sodium selenite at 17.50 micromol/L was better than 8.75 micromol/L while cadmium chloride at 17.50 and 35.00 micromol/L.

CONCLUSIONThe antagonistic effect of selenium on rat hepatocellular DNA damage induced by cadmium related to the concentrations of selenium and also to the concentration ratio between selenium and cadmium.

Animals ; Cadmium ; toxicity ; Comet Assay ; DNA ; drug effects ; genetics ; DNA Damage ; drug effects ; Dose-Response Relationship, Drug ; Hepatocytes ; cytology ; drug effects ; metabolism ; Rats ; Selenium ; pharmacology

OBJECTIVETo study DNA damage of workers occupationally exposed to lead with flow cytometer assay.

METHODSThe lymphocytes were obtained from 41 workers occupationally exposed to lead (comparable group) and another 50 from control group. Flow cytometer (FCM) assay was used to detect DNA damage.

RESULTSDNA damage rate and geometric mean fluorescence intensity in the comparable group were significantly higher than those in the control group (P<0.05). There were no significant differences in the DNA damage and geometric mean fluorescence intensity between different age groups (P>0.05). The differences in correlation analysis between blood lead, urine lead, delta-ALA and DNA damage rate were not significant (P>0.05). The correlation analysis showed no statistical significance between concentration of blood lead, urine lead, delta-ALA and geometric mean fluorescence intensity (P>0.05). There was positive correlations not only between the high concentration of blood lead, delta-ALA and damage rate of DNA, but also between the high concentration of blood lead and geometric mean fluorescence intensity. The coefficient r showed statistical significance (P<0.05).

CONCLUSIONOccupational lead exposure can cause DNA damage. Gamma H2AX flow cytometer assay is a sensitive, objective and effective method for detection of DNA damage of peripheral blood lymphocytes.

DNA Damage ; drug effects ; Flow Cytometry ; Humans ; Lead ; adverse effects ; Lymphocytes ; drug effects ; Occupational Exposure ; adverse effects

This study was aimed to investigate the effects and the mechanism of mangiferin on chronic myeloid leukemia cell lines K562 cells in vitro. The antiproliferation effects of mangiferin on K562 leukemia cells were tested by tetrazolium salt (MTT) method; the apoptosis induced by mangiferin on K562 cell line was explored by means of cell morphology, DNA gel electrophoresis and flow cytometry. The changes in bcr/abl gene expression was detected by using reverse transcriptase (RT)-PCR. The results showed that five different concentrations of mangiferin (25 - 200 micromol/L) dose-dependently and time-dependently inhibited the proliferation of K562 cells, and induced apoptosis in K562 cell line. RT-PCR revealed that bcr/abl gene expression was down-regulated when K562 cells had been treated with different concentrations of mangiferin. In conclusion, mangiferin remarkably inhibits the proliferation of K562 leukemia cells in vitro, and induces apoptosis in K562 cell line probably through down-regulation of bcr/abl gene expression.
Apoptosis ; drug effects ; Cell Proliferation ; drug effects ; DNA Fragmentation ; drug effects ; Flow Cytometry ; Genes, abl ; Humans ; K562 Cells ; Xanthones ; pharmacology

Cells, Cultured ; Comet Assay ; DNA Damage ; drug effects ; Dose-Response Relationship, Drug ; Humans ; Lymphocytes ; drug effects ; Styrene ; adverse effects

The defect or block of apoptosis is an important factor involved in the drug resistance of tumor cells. Blm gene plays a great role in DNA damage and repair. This study was aimed to explore the relationship of blm gene expression with cell cycle and apoptosis after Jurkat DNA damage. The apoptosis rate and change of cell cycle were detected by flow cytometry, the expression level of blm mRNA in Jurkat cells was determined by semi-quantitative RT-PCR. The results indicated that after induction with 0.4 g/L of mitomycin C (MMC) for 24 hours the apoptosis rate of Jurkat cells were (11.42±0.013)%, and (66.08±1.60)% Jurkat cells were arrested in G2/M phase. After induction for 48 hours, the apoptosis rate of Jurkat cells declined from (11.42±0.013)% to (8.08±0.27)%, and cell count of Jurkat cells arrested in G2/M phase decreased from (66.08±1.60)% to (33.96±1.05)%. When induced with 0.4 g/L of MMC for 24 hours, the apoptosis rate of fibroblasts and the percentage of fibroblasts in G2/M, G0-G1 and S phase all showed no significant change until 48 hours. The range of apoptosis rate and the change of cell percentage in three phases were significantly different between Jurkat cells and fibroblasts (p<0.01). Expression level of blm mRNA in Jurkat cells was remarkably higher than that in normal fibroblasts (p<0.01), at 48 hours expression level of blm mRNA was remarkably higher than that at 24 hours. The 2 groups showed clear difference of blm mRNA expression after treated by MMC (p<0.01). It is concluded that the blm gene may play a significant role in repair of DNA damage of Jurkat cells after MMC induction. Abnormal expression of blm is correlated to the drug resistance of leukemia cells.
Apoptosis ; Cell Cycle ; DNA Damage ; drug effects ; DNA Repair ; drug effects ; Humans ; Jurkat Cells ; Mitomycin ; pharmacology ; RecQ Helicases ; genetics

OBJECTIVETo investigate the role of Annexin 5 in protecting human sperm membrane and DNA integrity.

METHODSWe collected 53 semen samples based on the criteria of sperm density > 20 x 10(6)/ml and motility > 60%, and divided them into an experimental group (2.5 microl 10(-6) mol/L Annexin 5 added to 47.5 microl semen), a negative control group (2.5 microl 1 mol/L Tris-HCl [pH 8.0, 25 degrees C] added to 47.5 microl semen), and a blank control group (2.5 microl 0.01 mol/L PBS [pH 7.4] added to 47.5 microl semen). After 20 minutes of incubation, we evaluated the sperm membrane integrity using the hypoosmotic swelling test and, after another 60 minutes of treatment with H2O2 at 2.5 microl 10.02 mol/L, measured the sperm nuclear DNA integrity by acridine orange fluorescent staining.

RESULTSAfter 20 minutes of treatment with Annexin 5, the experimental group showed extremely significant difference in the percentage of hypoosmotic swelling sperm ([66.17 +/- 12.02] %) from the blank control ([58.13 +/- 13.08]%, P < 0.01) and the negative control group ([59.94 +/- 11.91]%, P < 0.01), but there was no significant difference between the latter two. Treatment with H2O2 remarkably increased DFI in the experimental group (6.39 +/- 1.07) as compared with the blank control (11.16 +/- 1.16) and the negative control group (10.86 +/- 1.05, P < 0.01), but no significant difference was observed between the latter two.

CONCLUSIONAnnexin 5 can increase the percentage of hypoosmotic swelling sperm in vitro and protect sperm membrane integrity, and it can also protect sperm DNA from H2O2 damage.

Annexin A5 ; pharmacology ; Cell Membrane ; drug effects ; DNA ; DNA Fragmentation ; Humans ; Male ; Sperm Count ; Sperm Motility ; Spermatozoa ; drug effects