[Role of heat shock protein 70 expression in DNA damage induced by benzo(a)pyrene].
OBJECTIVE
To explore heat shock protein 70 (HSP70) expression of A549 cells and its role in DNA damage caused by benzo(a)pyrene (BaP).


METHODS
Human adenocarcinoma A549 cells were cultured in vitro, exposed by different concentrations of BaP (0, 1.25, 2.50, 5.00, 10.00 micro mol/L) for 6 hours, or 10 micro mol/L of BaP for different time (0, 4, 8, 12, 16, 24 and 48 h). Then HSP70 expression and DNA damage were detected using Western-blot and single cell gel electrophoresis (SCGE) assay respectively, and the relationship between HSP70 expression and DNA damage was further analyzed.


RESULTS
The integral optical densities of HSP70 in A549 cells treated with 1.25, 2.50, 5.00 and 10.00 micro mol/L BaP for 6 h (49.63 +/- 1.30, 45.72 +/- 1.03, 40.53 +/- 0.95, 37.50 +/- 1.20 respectively) were lower than that of the control cells (59.43 +/- 1.17) (P < 0.05). When A549 cells were exposed to 10 micro mol/L BaP for 4, 8, 12, 16 h, the integral optical densities of HSP70 were 33.33 +/- 0.80, 29.23 +/- 0.91, 12.51 +/- 0.96, 9.50 +/- 1.25 respectively, and there was an increasing tendency of the expression of HSP70 for 24 - 48 h (20.06 +/- 1.38, 24.51 +/- 1.39), however, all were different from that in control group (56.59 +/- 0.85) (P < 0.05). DNA damage scores in 10(6) A549 cells treated with 2.50, 5.00 and 10.00 micro mol/L BaP for 6 h (23,718 +/- 2,938, 30,128 +/- 2,937, 44,231 +/- 3,846) were significantly higher than that of the control cell (9,615 +/- 1,923) (P < 0.05). When A549 cells were exposed to 10 micro mol/L BaP for 4, 8, 12, 16, 24, 48 h, DNA damage scores (16,667 +/- 4,003, 38,461 +/- 1,924, 5,615 +/- 3,847, 76,282 +/- 2,937, 7,513 +/- 1,110 and 58,975 +/- 9,487) were also higher than that of control group (P < 0.05). There was a negative correlation between DNA damage and the expression of HSP70 when A549 cells were exposed to different concentrations of BaP.


CONCLUSIONS
HSP70 might enhance intracellular defenses against DNA damage induced by BaP.
Xu
Qian
Q
Department of Labor Health and Environment Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Yang
Jin-bo
JB
Jiang
Chang-zheng
CZ
Yang
Miao
M
Ke
Lei
L
He
Mei-an
MA
Wang
Feng
F
Wu
Tang-chun
TC
D001564:Benzo(a)pyrene / Q000633:toxicity*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D020552:Comet Assay; D004247:DNA / Q000187:drug effects / Q000235:genetics; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis*; D006801:Humans; D013997:Time Factors
D018840:HSP70 Heat-Shock Proteins; D001564:Benzo(a)pyrene; D004247:DNA