The effects of benzene and the metabolites phenol and catechol on c-Myb and Pim-1 signaling in HD3 cells.
Exposure to the environmental toxicant benzene has been proposed to lead to leukemogenesis. The transcription factor c-Myb plays a role in blood cell differentiation and can be regulated by the serine-threonine kinase Pim-1. Overexpressed versions of c-Myb and Pim-1 are believed to play a key role in the development of a wide variety of leukemias and tumors. In our study, we evaluated the effects of benzene and the metabolites catechol and phenol on c-Myb signaling to investigate our hypothesis that benzene exerts its toxicity by interfering with this pathway. To evaluate this hypothesis, HD3 chicken erythroblast cells were transiently transfected with a c-Myb responsive luciferase reporter plasmid and then exposed to benzene, catechol, or phenol (0-300 microM) for 1-24 h before nonproprietary dual luciferase activities were measured. Our results demonstrated that catechol exposure caused a time- and concentration-dependent increase in c-Myb activity with significance occurring at 100 and 300 microM after 24 h of exposure, which was independent of increased Pim-1 protein, but dependent on increased c-Myb phosphorylation. Benzene and phenol exposure resulted in small but significant decreases in c-Myb activity that were not dose- and time-dependent, nor was increased Pim-1 protein involved. 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 metabolite-mediated alterations in the c-Myb signaling pathway.
Wan
Joanne
J
Department of Pharmacology and Toxicology, Queen's University, Kingston, ON, Canada K7L 3N6.
Winn
Louise M
LM
D000818:Animals; D001554:Benzene / Q000633:toxicity*; D002396:Catechols / Q000633:toxicity*; D002460:Cell Line; D002645:Chickens; D003720:Densitometry; D004305:Dose-Response Relationship, Drug; D004900:Erythroblasts; D020570:Genes, myb / Q000187:drug effects* / Q000235:genetics; D015151:Immunoblotting; D008156:Luciferases / Q000235:genetics; D019800:Phenol / Q000633:toxicity*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis* / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000235:genetics; D051573:Proto-Oncogene Proteins c-pim-1; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D014162:Transfection
D002396:Catechols; D011518:Proto-Oncogene Proteins; D019800:Phenol; D008156:Luciferases; D017346:Protein Serine-Threonine Kinases; D051573:Proto-Oncogene Proteins c-pim-1; D001554:Benzene; C034221:catechol