title: Benzene's metabolites alter c-MYB activity via reactive oxygen species in HD3 cells.
abstract: Benzene is a known leukemogen that is metabolized to form reactive intermediates and reactive oxygen species (ROS). The c-Myb oncoprotein is a transcription factor that has a critical role in hematopoiesis. c-Myb transcript and protein have been overexpressed in a number of leukemias and cancers. Given c-Myb's role in hematopoiesis and leukemias, it is hypothesized that benzene interferes with the c-Myb signaling pathway and that this involves ROS. To investigate our hypothesis, we evaluated whether benzene, 1,4-benzoquinone, hydroquinone, phenol, and catechol generated ROS in chicken erythroblast HD3 cells, as measured by 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate (DCFDA) and dihydrorhodamine-123 (DHR-123), and whether the addition of 100 U/ml of the antioxidating enzyme superoxide dismutase (SOD) could prevent ROS generation. Reduced to oxidized glutathione ratios (GSH:GSSG) were also assessed as well as hydroquinone and benzoquinone's effects on c-Myb protein levels and activation of a transiently transfected reporter construct. Finally we attempted to abrogate benzene metabolite mediated increases in c-Myb activity with the use of SOD. We found that benzoquinone, hydroquinone, and catechol increased DCFDA fluorescence, increased DHR-123 fluorescence, decreased GSH:GSSG ratios, and increased reporter construct expression after 24 h of exposure. SOD was able to prevent DCFDA fluorescence and c-Myb activity caused by benzoquinone and hydroquinone only. These results are consistent with other studies, which suggest metabolite differences in benzene-mediated toxicity. More importantly, this study supports the hypothesis that benzene may mediate its toxicity through ROS-mediated alterations in the c-Myb signaling pathway.
authors.affiliation: Department of Pharmacology and Toxicology, Queen's University, Kingston, Ontario, Canada.
authors.forename: Joanne
authors.initials: J
authors.lastname: Wan
authors.forename: Louise M
authors.initials: LM
authors.lastname: Winn
mesh_terms: D000123:Acetyltransferases / Q000235:genetics; D000818:Animals; D001554:Benzene / Q000378:metabolism / Q000633:toxicity*; D001555:Benzene Derivatives / Q000378:metabolism / Q000633:toxicity*; D016227:Benzoquinones / Q000633:toxicity; D002273:Carcinogens / Q000633:toxicity; D002460:Cell Line; D002645:Chickens; D004305:Dose-Response Relationship, Drug; D004900:Erythroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005452:Fluoresceins / Q000737:chemistry / Q000378:metabolism; D005453:Fluorescence; D016166:Free Radical Scavengers / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D006873:Hydroquinones / Q000633:toxicity; D015151:Immunoblotting; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D019800:Phenol / Q000633:toxicity; D011092:Polyethylene Glycols / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D020598:Proto-Oncogene Proteins c-myb / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012235:Rhodamines / Q000737:chemistry / Q000378:metabolism; D013482:Superoxide Dismutase / Q000494:pharmacology; D014162:Transfection
chemical_list: D001555:Benzene Derivatives; D016227:Benzoquinones; D002273:Carcinogens; D005452:Fluoresceins; D016166:Free Radical Scavengers; D006873:Hydroquinones; D020598:Proto-Oncogene Proteins c-myb; D017382:Reactive Oxygen Species; D012235:Rhodamines; C058319:dihydrorhodamine 123; C029569:diacetyldichlorofluorescein; D019800:Phenol; C004532:quinone; D011092:Polyethylene Glycols; D008156:Luciferases; D013482:Superoxide Dismutase; C063471:polyethylene glycol-superoxide dismutase; D000123:Acetyltransferases; C077509:mim-1 protein, Gallus gallus; D005978:Glutathione; D001554:Benzene; D019803:Glutathione Disulfide; C031927:hydroquinone