Detection of 8-oxo-2'-deoxyguanosine, a marker of oxidative DNA damage, in culture medium from human mesothelial cells exposed to crocidolite asbestos

Our plain-English summary of Detection of 8-oxo-2'-deoxyguanosine, a marker of oxidative DNA damage, in culture medium from human mesothelial cells exposed to crocidolite asbestos, by Q. Chen, J. Marsh, B. Ames, et al (Carcinogenesis, 1996).

The study

• Authors: Q. Chen, J. Marsh, B. Ames, B. Mossman
• Journal: Carcinogenesis
• Published: 1996;17(11):2525-7
• Cited by: 35 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Crocidolite asbestos is associated with the development of mesothelioma. Although chromosomal changes have been documented in mesothelial cells, the mechanisms of interaction of crocidolite with DNA remain obscure. Since human mesothelial cells are exquisitely sensitive to asbestos, oxidative DNA damage was measured in an asbestos-exposed human mesothelial cell line (MET5A) by assaying oxidized guanine bases [8-oxo-2'-deoxyguanosine (oxo8dG), 8-oxoguanine (oxo8G), and 8-oxoguanosine (oxo8Gua)] excreted into the spent culture medium after DNA repair or turnover. At growth inhibitory, but not cytolytic concentrations, asbestos caused significant elevation of all bases in the spent medium over a 48-h period. In contrast, riebeckite, a chemically similar, nonfibrous analog of crocidolite did not cause increased adduct release. Results show that oxidative RNA and DNA bases are produced in response to asbestos in target cells of asbestos-induced cancers.

In plain English

This short laboratory report studied an immortalized line of human pleural mesothelial cells (MET5A) grown in culture, not people. The authors exposed the cells to crocidolite asbestos or to riebeckite, a non-fibrous mineral chemically similar to crocidolite. They then measured three oxidized forms of guanine that cells release into their culture medium after repair or turnover of damaged DNA and RNA. Crocidolite at 10 micrograms per square centimeter of dish slowed cell growth over up to 72 hours. The authors judged this dose not cytolytic (not causing cells to break apart), although they saw some focal cell sloughing at about 8 hours. At 24 hours, levels of the oxidized bases were not significantly raised. At 48 hours, all three were elevated (p less than 0.05), by about 1.5 to 2 times. Riebeckite at the same dose did not increase their release. The authors concluded that oxidative DNA and RNA damage occurs in human mesothelial cells after asbestos exposure. They noted that the two minerals were compared by equal weight, so particle numbers or surface area may have differed.

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: Laboratory (in vitro) cell culture experiment, published as a short communication
• Who was studied: An immortalized human pleural mesothelial cell line (MET5A) grown in culture; spent medium was pooled from five dishes per treatment group
• Exposure: NIEHS reference sample of crocidolite asbestos, compared with riebeckite (a non-fibrous, chemically similar particle), added to confluent cells for 24 or 48 hours; main experiments used 10 micrograms per square centimeter of dish
• Main results:
  • At 10 micrograms per square centimeter of dish, crocidolite reduced cell protein compared with untreated cells, and the authors judged it growth inhibitory but not cytolytic for up to 72 hours. A concentration of 20 micrograms per square centimeter caused obvious sloughing of cells.
  • At the 10 micrograms per square centimeter dose, the authors observed some focal cell sloughing at about 8 hours. They said the later accumulation of oxidized bases was not associated with extensive cell death.
  • At 24 hours, release of the oxidized bases into the medium by asbestos-exposed MET5A cells was not significantly increased.
  • At 48 hours, all three oxidized bases were elevated (p less than 0.05) in medium from asbestos-exposed MET5A cells compared with controls.
  • Over 48 hours, riebeckite at the same concentration did not increase release of the oxidized bases, whereas crocidolite exposure was associated with about 1.5 to 2-fold increases in all of them.
• The authors' conclusion: The authors concluded that their data confirm that oxidative DNA and RNA damage occurs in human mesothelial cells after asbestos exposure, supporting the hypothesis that asbestos fibers damage cells through an oxidative mechanism.
• Limitations the authors state:
  • Riebeckite and crocidolite were compared at equal weight concentrations, so the numbers of particles or their surface area per unit area may have differed.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelial Cells, Crocidolite, Mesothelioma, Riebeckite.

Related studies

• Patterns of 8-hydroxydeoxyguanosine formation in DNA and indications of oxidative stress in rat and human pleural mesothelial cells after exposure to crocidolite asbestos — H. Fung, Y.W. Kow, et al. (1997)
• 8-Hydroxy-2'-deoxyguanosine as a marker of oxidative DNA damage related to occupational and environmental exposures — A. Pilger, H.W. Rüdiger (2006)
• Determination of carcinogenic potential of mineral fibers by 8-hydroxydeoxyguanosine as a marker of oxidative DNA damage in mammalian cells — N. Murata-Kamiya, T. Tsutsui, et al. (1997)
• 8-hydroxy-2' -deoxyguanosine (8-OHdG): A critical biomarker of oxidative stress and carcinogenesis — A. Valavanidis, T. Vlachogianni, et al. (2009)
• Phagocytosis of crocidolite asbestos induces oxidative stress, DNA damage, and apoptosis in mesothelial cells — W. Liu, J.D. Ernst, et al. (2000)
• Exposure to nano-size titanium dioxide causes oxidative damages in human mesothelial cells: The crystal form rather than size of particle contributes to cytotoxicity — K. Hattori, K. Nakadate, et al. (2017)

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