[mRNA expression levels of p53 and DNA damage and repair genes in peripheral blood lymphocytes of benzene-exposed workers].
OBJECTIVE
To investigate the relationship between the mRNA expression levels of p53-mediating DNA damage and repair genes in the peripheral blood lymphocytes of workers and their exposures to benzene in their working environment.


METHODS
The mRNA expression levels of p53 and related genes were determined by SYBR Green I chimeric fluorescence quantitative real-time RT-PCR analysis in peripheral blood lymphocytes of 72 workers, who were classified into group A (46 direct exposure to benzene) and group B (26 indirect exposure to benzene) based on their positions, and 29 controls. The differences of gene expression levels were analyzed by software REST 2005. Meanwhile, the peripheral blood leukocytes, hemoglobin and platelet of workers and controls were counted. Benzene content was measured in the samples of toluene, used as raw material, and spraying agents and benzene, toluene and xylene concentrations in the air of workplaces were monitored.


RESULTS
There were no significant differences in the mRNA expression levels of p53, Ku80, Ape1 and Mdm-2 between group A or group B and control group (P > 0.05). The expression up-regulation of p21 mRNA was found, but without significant difference (P > 0.05). However, the mRNA expression levels of Rad51, Bcl-2, Bax, Xpa and Xpc in group A and Rad51 in group B were downregulated significantly (P < 0.05 or P < 0.01). Moreover, both the counts of white blood cell, hemoglobin and platelet in group A were (4.93 +/- 1.27) x 10(9)/L, (123.97 +/- 11.80) g/L and (124.02 +/- 41.22) x 10(9)/L respectively and platelet in group B (135.80 +/- 39.44) x 10(9)/L were significantly lower than in control group (P < 0.05 or P < 0.01).


CONCLUSIONS
The mRNA expression levels of some p53-mediating DNA damage and repair genes are downregulated in the workers chronically exposed to low benzene concentration. The working environment impacts on health of group A workers are greater than the ones of group B.
Ye
Rong
R
Hangzhou Center for Disease Control and Prevention, Hangzhou 310006, China.
Pan
Jin-cao
JC
Cao
Jian-zhong
JZ
Guan
Ji-ru
JR
Xie
Xiao-ming
XM
Yu
Ai-xv
AX
Wu
Long
L
He
Yue-long
YL
Xia
Zhao-ling
ZL
D000328:Adult; D001554:Benzene / Q000009:adverse effects*; D004249:DNA Damage; D004260:DNA Repair; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D016273:Occupational Exposure / Q000009:adverse effects*; D012333:RNA, Messenger / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D055815:Young Adult
D012333:RNA, Messenger; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D001554:Benzene