Increased gene expression in human promyeloid leukemia cells exposed to trans,trans-muconaldehyde, a hematotoxic benzene metabolite.
The hematotoxicity of benzene, a human leukemogen, has been postulated to be mediated by reactive metabolites and involve cell damage caused by reactive oxygen species. Because expression of the transcription factors AP-1 and NF-kappaB is sensitive to the redox state in eukaryotic cells, the DNA binding activity of AP-1 and NF-kappaB was examined in HL-60 promyeloid leukemia cells exposed to trans,trans-muconaldehyde, a microsomal hematotoxic metabolite of benzene. There was little AP-1 binding activity in nuclear extracts from control HL-60 cells based on electrophoretic mobility shift assays. Exposure to 0.1 microM MUC for 4 h resulted in significantly increased levels of nuclear protein with high sequence specificity for the consensus AP-1 sequence. In addition, electrophoretic mobility shift assays showed a strong increase in the binding of a factor to the NF-kappaB site. The latter was highest in nuclear extracts from HL-60 cells treated with 1.0 microM muconaldehyde and cultured for 4 h. Exposure of HL-60 cells to muconaldehyde resulted in an increase in c-fos and c-jun mRNA levels. Western blot analysis showed that the protein levels of c-jun increased in HL-60 cells treated with 1 microM muconaldehyde and cultured for 4-6 h and subsequently decreased gradually. Increased AP-1 binding was observed in bone marrow cells from B6C3F1 mice 2 h after administration of 440 mg/kg benzene. We suggest that increased gene expression of NF-kappaB and AP-1 binding activity and up-regulation of c-fos and c-jun may play a role in the mechanism of benzene leukemogenesis.
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UMDNJ-Robert Wood Johnson Medical School, Department of Environmental and Community Medicine, Piscataway, NJ 08855, USA.
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D000447:Aldehydes / Q000633:toxicity*; D000818:Animals; D001554:Benzene / Q000633:toxicity; D001853:Bone Marrow / Q000187:drug effects* / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D016762:Genes, fos; D016758:Genes, jun; D018922:HL-60 Cells; D006801:Humans; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015854:Up-Regulation
D000447:Aldehydes; D016328:NF-kappa B; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; C034476:muconaldehyde; D004247:DNA; D001554:Benzene