Association between mitochondrial DNA copy number, blood cell counts, and occupational benzene exposure.
Benzene is a recognized hematotoxicant and carcinogen that produces genotoxic damage. Benzene metabolites can produce reactive oxidative species. Mitochondrial DNA (mtDNA) copy number may be increased in response to oxidative stress to compensate for damaged mitochondria. We carried out a cross-sectional study of 40 benzene-exposed workers and 40 controls to evaluate the association between benzene exposure and mtDNA copy number. Copy number of mtDNA in leukocyte DNA was determined by real-time PCR. Compared with controls, the copy number of mtDNA increased by 4% and by 15% in workers exposed to < or =10 ppm (n = 20) and >10 ppm (n = 20) benzene, respectively. After adjusting for recent infection, the factor that was significantly correlated with mtDNA, the increase of mtDNA was statistically significant in the high exposed group (P = 0.016) with a significant linear trend (P = 0.024). To our best knowledge, this is the first report that benzene exposure was associated with increased mitochondria DNA copy number. Benzene exposure may induce mtDNA amplification, possibly in response to oxidative stress caused by benzene. The finding needs to be replicated by other studies.
Shen
Min
M
Division of Cancer Epidemiology and Genetics, NCI, NIH, DHHS, Bethesda, Maryland 20892-7240, USA. shenmi@mail.nih.gov
Zhang
Luoping
L
Bonner
Matthew R
MR
Liu
Chin-San
CS
Li
Guilan
G
Vermeulen
Roel
R
Dosemeci
Mustafa
M
Yin
Songnian
S
Lan
Qing
Q
D000328:Adult; D001554:Benzene / Q000506:poisoning*; D001772:Blood Cell Count / Q000379:methods*; D003430:Cross-Sectional Studies; D004272:DNA, Mitochondrial / Q000187:drug effects* / Q000235:genetics; D004785:Environmental Pollutants / Q000506:poisoning; D005260:Female; D018628:Gene Dosage; D006801:Humans; D016014:Linear Models; D008297:Male; D009245:NADH Dehydrogenase / Q000235:genetics; D016273:Occupational Exposure / Q000032:analysis*; D016133:Polymerase Chain Reaction
D004272:DNA, Mitochondrial; D004785:Environmental Pollutants; D009245:NADH Dehydrogenase; C515075:NADH dehydrogenase subunit 1, human; D001554:Benzene