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Asbestos induction of nuclear transcription factors and interleukin 8 gene regulation.

Authors
Simeonova-PP; Luster-MI
Source
Am J Respir Cell Mol Biol 1996 Dec; 15(6):787-795
NIOSHTIC No.
20034000
Abstract
Proinflammatory cytokines and chemotactic peptides are strongly implicated as mediators of the pathophysiologic responses of asbestosis and other chronic inflammatory lung diseases. Recent studies in our laboratory have demonstrated that asbestos fibers stimulate lung epithelial cells to produce interleukin-8 (IL-8), the major neutrophil chemoattractant in the lung. The mechanisms by which asbestos regulates IL-8 expression were studied using the pulmonary type II-like epithelial cell line A549. Membrane permeable hydroxyl scavengers inhibited asbestos induced IL-8 expression. Using A549 cells transfected with the -546 IL-8 construct linked to a chloramphenicol acetyl transferase reporter gene, we have shown that these antioxidants directly inhibited asbestos-stimulated IL-8 promoter-dependent transcription. Asbestos fibers as well as reactive oxygen species generating systems hypoxanthine-xanthine oxidase and hydrogen peroxide stimulated DNA binding activity to the regulatory elements in the IL-8 promoter, binding sites of nuclear factor (NF)-kappaB- and NF-IL-6-like transcription factors. Asbestos-inducible DNA binding activity was partially inhibited by tetramethylthiourea, a hydroxyl radical scavenger. IL-8 secretion was also suppressed by staurosporine, an inhibitor of protein kinase C, and by inhibitors of tyrosine kinase such as herbimycin A and genistein. The suppression paralleled the effect of these inhibitors on asbestos-induced DNA binding to the NF- kappaB- and NF-IL-6-like binding sites of the IL-8 promoter. Taken together, the results suggest that asbestos-induced redox changes and phosphorylation events, mediated by staurosporine-sensitive and tyrosine kinase(s), activate nuclear proteins which recognize the NF- kappaB/NF-IL-6 binding sites of the IL-8 promoter and contribute to the regulation of IL-8 gene expression.
Keywords
Asbestos-fibers; Asbestos-dust; Cytotoxins; Chronic-degenerative-diseases; Chronic-inflammation; Fibrous-dusts; Dust-particles; Dust-exposure; Genotoxic-effects; Gene-mutation
CODEN
AJRBEL
CAS No.
1332-21-4
Publication Date
19961201
Document Type
Journal Article
Fiscal Year
1997
NTIS Accession No.
NTIS Price
Issue of Publication
6
ISSN
1044-1549
NIOSH Division
HELD
Source Name
American Journal of Respiratory Cell and Molecular Biology
State
WV; NC
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