Possible role of lipid peroxidation in the induction of NF-kappa B and AP-1 in RFL-6 cells by crocidolite asbestos: evidence following protection by vitamin E

Our plain-English summary of Possible role of lipid peroxidation in the induction of NF-kappa B and AP-1 in RFL-6 cells by crocidolite asbestos: evidence following protection by vitamin E, by S.P. Faux, P.J. Howden (Environmental Health Perspectives, 1997).

The study

• Authors: S.P. Faux, P.J. Howden
• Journal: Environmental Health Perspectives
• Published: 1997;105 Suppl 5(Suppl 5):1127-30
• Cited by: 45 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Asbestos fibers cause persistent induction of the oxidative stress sensitive transcription factors nuclear factor kappa-B (NF-kappa B) and activator protein-1 (AP-1) in mammalian cells. These transcription factors play an important role in the regulation of cellular activity. Lipid peroxidation, mediated by reactive oxygen species, is thought to be a possible mechanism in the pathogenicity of asbestos fibers. These studies were designed to determine if crocidolite asbestos-induced lipid peroxidation plays a role in the mechanism of formation of NF-kappa B and AP-1. Treatment of a rat lung fibroblast cell line (RFL-6) with crocidolite asbestos in the presence and absence of the membrane antioxidant vitamin E decreased the levels of crocidolite-induced AP-1 and NF-kappa B to background levels. Preincubation of RFL-6 cells with 5,8,11,14-eicosatetraynoic acid, an inhibitor of arachidonic acid metabolism, prior to exposure to crocidolite, abrogated crocidolite-induced NF-kappa B DNA-binding activity to background levels. Coincubation with indomethacin, a cyclooxygenase inhibitor, had no effect on NF-kappa B DNA-binding activity induced by crocidolite. However, nordihydroguaiaretic acid, a lipoxygenase inhibitor, decreased levels of NF-kappa B to background levels. This would suggest that lipoxygenase metabolites of arachidonic acid, produced following lipid peroxidation, are involved in the cellular signalling events to NF-kappa B transcription factor induction by asbestos.

In plain English

This was a laboratory study of a rat lung fibroblast cell line called RFL-6, not of people or whole animals. The authors exposed the cells to crocidolite asbestos and measured the DNA-binding activity of NF-kappa B and AP-1, two transcription factors sensitive to oxidative stress. Crocidolite increased the DNA-binding activity of both in a time- and dose-dependent way. The largest increases were at 8 and 24 hours at 5 and 10 micrograms per square centimetre. Vitamin E blocks lipid peroxidation, which is damage to fats in cell membranes. When vitamin E was added, the authors reported that DNA binding of both factors fell to background levels. ETYA, which blocks the metabolism of arachidonic acid, reduced NF-kappa B DNA binding to background levels: 7.54 relative units, against 10.69 with crocidolite alone and 7.11 in controls. Indomethacin, which blocks the cyclooxygenase pathway, did not change NF-kappa B DNA binding. NDGA, which blocks the lipoxygenase pathway, significantly reduced it, to basal levels according to the authors. The authors concluded that their results suggest lipoxygenase products of arachidonic acid, formed after lipid peroxidation, are involved in the signals leading to NF-kappa B induction by asbestos.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: in vitro (cell culture) laboratory experiment
• Who was studied: A rat lung fibroblast cell line (RFL-6), obtained from the European Collection of Animal Cell Cultures, U.K.; results were based on three samples per treatment (n=3)
• Exposure: Union Internationale Contre le Cancer (UICC) reference crocidolite at 2.5, 5 and 10 micrograms per square centimetre for 4, 8 and 24 hours. Further 8-hour treatments used crocidolite (5 and/or 10 micrograms per square centimetre) with or without vitamin E (0.5 and 2 mM), indomethacin (50 and 100 micromolar), NDGA (10 and 50 micromolar) or ETYA (5 micromolar).
• Main results:
  • In RFL-6 cells, crocidolite increased NF-kappa B and AP-1 in a time- and dose-dependent manner. Maximum induction was at 8 and 24 hours at 5 and 10 micrograms per square centimetre (p less than 0.05). The assay measured DNA-binding activity, using gel mobility shift assays.
  • Vitamin E at both concentrations reduced the crocidolite-induced increase in AP-1 and NF-kappa B DNA binding (p less than 0.05)
  • The authors described the DNA binding of AP-1 and NF-kappa B with crocidolite plus vitamin E as reduced to background levels
  • NF-kappa B DNA binding (relative units, mean with standard error, n=3) was 7.11 plus or minus 0.55 in controls and 10.69 plus or minus 0.16 with crocidolite (5 micrograms per square centimetre). With crocidolite plus ETYA it was 7.54 plus or minus 0.04, significantly lower than with crocidolite alone (p less than 0.05).
  • The cyclooxygenase inhibitor indomethacin did not alter crocidolite-induced NF-kappa B DNA binding
  • The lipoxygenase inhibitor NDGA significantly reduced crocidolite-induced NF-kappa B DNA binding compared with crocidolite alone (p less than 0.05)
  • The authors described NF-kappa B DNA binding with crocidolite plus NDGA as reduced to basal levels
• The authors' conclusion: The authors concluded that their findings suggest lipoxygenase metabolites of arachidonic acid, produced following lipid peroxidation, are involved in the cellular signalling leading to NF-kappa B induction by asbestos
• Limitations the authors state:
  • The authors had not yet identified which lipoxygenase product or products are involved; further studies were in progress

Topics

The National Library of Medicine indexes this study under subjects our site covers: Crocidolite.

Medical terms in this study, explained in our Lexicon: Crocidolite, Oxidative Stress, Reactive Oxygen Species (ROS), Fibroblast.

Related studies

• Fibre-induced lipid peroxidation leads to DNA adduct formation in Salmonella typhimurium TA104 and rat lung fibroblasts — P.J. Howden, S.P. Faux (1996)
• Chrysotile inhibits glutathione-dependent protection against the onset of lipid peroxidation in rat lung microsomes — J.M. Arif, I. Ahmad, et al. (1996)
• Crocidolite activates NF-kappa B and MIP-2 gene expression in rat alveolar epithelial cells. Role of mitochondrial-derived oxidants — K.E. Driscoll, J.M. Carter, et al. (1998)
• Asbestos induces nuclear factor kappa B (NF-kappa B) DNA-binding activity and NF-kappa B-dependent gene expression in tracheal epithelial cells — Y.M. Janssen, A. Barchowsky, et al. (1995)
• Asbestos causes translocation of p65 protein and increases NF-kappa B DNA binding activity in rat lung epithelial and pleural mesothelial cells — Y.M. Janssen, K.E. Driscoll, et al. (1997)
• Lipid peroxidation and disintegration of the cell membrane structure in cultures of rat lung fibroblasts treated with asbestos — H. Iguchi, S. Kojo, et al. (1993)

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