ToxSci Advance Access published online on October 7, 2009
Toxicological Sciences, doi:10.1093/toxsci/kfp242
In Utero Exposure to Benzene Disrupts Fetal Hematopoietic Progenitor Cell Growth Via Reactive Oxygen Species1
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* Department of Pharmacology and Toxicology. Queen's University, Kingston, Ontario, Canada. K7L 3N6
School of Environmental Studies. Queen's University, Kingston, Ontario, Canada. K7L 3N6
2 Corresponding author. Tel: 1+(613)-533-6465; Fax: 1+(613)-533-6412; E-mail: winnl{at}queensu.ca; Mailing address: Room 557 Botterell Hall, Queen's University, Kingston, Ontario, Canada, K7L 3N6
Received July 17, 2009; revision received September 30, 2009; accepted October 1, 2009
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Abstract |
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It is hypothesized that the increasing incidence of childhood leukemia may be due to in utero exposure to environmental pollutants such as benzene, but the mechanisms involved remain unknown. We hypothesize that reactive oxygen species (ROS) contribute to the deregulation of fetal hematopoiesis caused by in utero benzene exposure. To evaluate this hypothesis, pregnant C57Bl/6N mice were exposed to benzene or PEG-catalase (antioxidative enzyme) and benzene. Colony formation assays on fetal liver cells were performed to measure erythroid and myeloid progenitor cell growth potential. The presence of ROS in CD117+ fetal liver cells was measured by flow cytometric analysis. Oxidative cellular damage was assessed by Western blot analysis of 4-hydroxynonenol and nitrotyrosine products, as well as reduced to oxidized glutathione ratios. Alterations in the redox sensitive signaling pathway NF-
B were measured by Western blot analysis of IB-
protein levels in fetal liver tissue. Results: In utero exposure to benzene caused a significant increase in ROS production and significantly altered fetal liver erythroid and myeloid colony numbers, but did not increase the levels of 4-HNE or nitrotyrosine products or alter reduced to oxidized glutathione ratios. However, in utero exposure to benzene did cause a significant decrease in fetal liver IB- protein levels suggesting activation of the NF-B pathway. Benzene-induced ROS formation, abnormal colony growth, and decreased IB- levels were all abrogated by pre-treatment with PEG-catalase. These results suggest that ROS play a key role in the development of in utero-initiated benzene toxicity potentially through disruption of hematopoietic cell signaling pathways.
Key Words: Benzene; in utero; reactive oxygen species; hematopoietic progenitor cells; NF-B.
1 Preliminary reports of this research were presented at the 47th annual meeting of the Society of Toxicology, March 2008; the 48th annual meeting of the Teratology Society (U.S.A.), June 2008; and at the 40th annul meeting of the Society of Toxicology of Canada, December 2008.