Study of the cell-transforming ability of amosite and crocidolite asbestos and the ability to induce changes in the metabolism and macromolecular binding of benzo(a)pyrene in C3H10T1/2 cells

Our plain-English summary of Study of the cell-transforming ability of amosite and crocidolite asbestos and the ability to induce changes in the metabolism and macromolecular binding of benzo(a)pyrene in C3H10T1/2 cells, by A. Poole, R.C. Brown, G.T. Fleming (Environmental Health Perspectives, 1983).

The study

• Authors: A. Poole, R.C. Brown, G.T. Fleming
• Journal: Environmental Health Perspectives
• Published: 1983;51:319-24
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The cell transforming ability of asbestos dusts was investigated using C3H10T1/2 murine fibroblasts. In a series of experiments, crocidolite and amosite caused no increase in the number of transformed colonies over that seen in cultures from untreated cells. The dusts were, however, capable of augmenting the oncogenic effect of benzo(a)pyrene. This synergistic effect was evident when fibers and chemicals were added to cultures as simple mixtures and when benzo(a)pyrene was adsorbed to the surface of fibers. Asbestos dust did not, however, appear to exert its oncogenic enhancing effect by modifying the metabolism of benzo(a)pyrene in C3H10T1/2 cells.

In plain English

This laboratory study used mouse embryo cells (C3H10T1/2 cells); no people were studied. The authors tested UICC standard crocidolite and amosite asbestos, and milled amosite. Milled amosite was tested only alone; crocidolite and amosite were also combined with the chemical carcinogen benzo(a)pyrene (BaP), as a mixture or with BaP coated onto the fibers. Over four experiments they counted transformed colonies (foci), a laboratory sign of cancer-like change. The dusts alone produced no significant increase in transformed cultures compared with untreated controls. In experiment 2, amosite mixed with BaP gave on average 0.45 foci per culture, against 0.20 for BaP alone; in experiment 4, crocidolite with BaP gave 0.24, against 0.05. With BaP coated onto the dust, the averages were 0.35, 0.43 and 0.60 foci per culture in experiments 2, 3 and 4, against 0.20, 0.07 and 0.05 for BaP alone. Tests of whether crocidolite changed how the cells processed BaP gave variable results. The authors concluded that the dusts could augment the oncogenic effect of BaP. They called the metabolism results equivocal.

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 experiment: cell transformation assays and benzo(a)pyrene metabolism studies in cultured mouse cells
• Who was studied: The C3H10T1/2 (10T1/2 Cl 8) cell line, derived from C3H mouse embryo fibroblasts; four transformation experiments and three metabolism experiments
• Exposure: UICC standard crocidolite and amosite, plus milled amosite (milled 4 hr). Milled amosite was tested only alone (experiment 1). Crocidolite and unmilled amosite were also tested with benzo(a)pyrene (BaP), either in acetone solution or adsorbed onto the dust surface. In the transformation tables, dust doses were 5 or 10 µg/mL and BaP doses were 0.1, 0.3 or 2.5 µg/mL. The metabolism studies used crocidolite at 100 or 10 µg/mL.
• Main results:
  • None of the dusts tested alone (amosite, crocidolite, milled amosite) produced a significant increase in transformed cultures compared with negative controls.
  • The authors reported that exposing cells to crocidolite or amosite together with BaP caused a significant increase in transformed foci.
  • Experiment 2 (Table 2), mean transformed foci per culture: BaP alone (0.3 µg/mL) 0.20 (6 of 35 dishes with foci); amosite plus BaP mixture 0.45 (10 of 33); amosite with BaP adsorbed 0.35 (8 of 34).
  • Experiment 3 (Table 2), mean transformed foci per culture: BaP alone (0.3 µg/mL) 0.07 (3 of 44 dishes with foci); crocidolite with BaP adsorbed 0.43 (8 of 47).
  • Experiment 4 (Table 2), mean transformed foci per culture: BaP alone (0.1 µg/mL) 0.05 (1 of 20 flasks with foci); crocidolite plus BaP mixture 0.24 (2 of 21); crocidolite with BaP adsorbed 0.60 (1 of 20, a single culture with 12 foci).
  • Transformation frequency rose in parallel. Enhancement ratios were 4.1 and 16.3 times for the dust-BaP mixtures, and 1.5, 8 and 12 times for BaP adsorbed onto dust.
  • Dust and BaP given together killed more cells than either agent alone.
  • In the metabolism studies, crocidolite-treated and untreated cells did not differ significantly in organic-soluble BaP metabolites in any of the three experiments.
  • In experiment 3, cells given BaP adsorbed onto crocidolite showed a reduced proportion of BaP converted to water-soluble products.
  • Binding of BaP to cell protein and DNA was variable. It was lower in crocidolite-treated cells in experiment 1 (crocidolite 100 µg/mL) and higher in crocidolite-treated cells in experiments 2 and 3 (10 µg/mL).
• The authors' conclusion: The authors concluded that asbestos dusts alone produced no significant increase in transformed foci but could augment the oncogenic effect of benzo(a)pyrene. They described the metabolism results as equivocal and suggested further study.
• Limitations the authors state:
  • The metabolism data were so variable that no firm conclusions could be drawn about whether asbestos changed BaP metabolism.
  • In experiments 1 to 3, the attempt to keep the number of surviving cells constant across treatment groups failed because survival varied between experiments, so a different protocol was used in experiment 4.

Topics

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

Medical terms in this study, explained in our Lexicon: Amosite, Crocidolite, Fibroblast, Synergistic Effect.

Related studies

• Effects of crocidolite and chrysotile asbestos on cellular uptake and metabolism of benzo(a)pyrene in hamster tracheal epithelial cells — B.T. Mossman, A. Eastman, et al. (1983)
• Asbestos and benzo(a)pyrene synergism in the transformation of Syrian hamster embryo cells — J.A. DiPaolo, A.J. DeMarinis, et al. (1983)
• Studies on in vitro chrysotile-pleural mesothelial cell interaction: morphological aspects and metabolism of benzo-3,4-pyrene — M.C. Jaurand, I. Bastie-Sigeac, et al. (1983)
• Effect of chrysotile asbestos and silica on the microsomal metabolism of benzo(a)pyrene — C. Kandaswami, P.J. O'Brien (1983)
• Pulmonary metabolism of benzo(a) pyrene : effect of asbestos — C. Kandaswami, P.J. O'Brien (1981)
• The effect of asbestos-associated metal ions on the binding of benzo(a)pyrene to macromolecules in vitro — R. Thomson, T.A. Kilroe-Smith, et al. (1978)

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