Asbestos and benzo(a)pyrene synergism in the transformation of Syrian hamster embryo cells

Our plain-English summary of Asbestos and benzo(a)pyrene synergism in the transformation of Syrian hamster embryo cells, by J.A. DiPaolo, A.J. DeMarinis, J. Doniger (Pharmacology, 1983).

The study

• Authors: J.A. DiPaolo, A.J. DeMarinis, J. Doniger
• Journal: Pharmacology
• Published: 1983;27(2):65-73
• Cited by: 33 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Four varieties of asbestos fibers, crocidolite, anthophyllite, amosite, and chrysotile, induced a low rate of morphologic transformation in Syrian hamster cells. Of the four tested, chrysotile was the most lethal as reflected by colony survival. When cells were exposed to 1 microgram of benzo(a)pyrene (BP)/1 ml medium or 3 J/m2 ultraviolet irradiation and to different concentrations of the asbestos fibers, an enhancement of transformation occurred only with BP. The enhancement was dose responsive with all fiber species except for amosite which was dose independent. The synergistic activity of BP and asbestos suggests that asbestos facilitates the transport of BP to the cell site(s) critical for transformation. These results provide a basis for investigating the carcinogenic and cocarcinogenic potential of asbestos fibers in mammalian cells.

In plain English

This was a laboratory experiment on cultured Syrian hamster embryo cells. The authors exposed the cells to four standard reference asbestos fibers (crocidolite, amosite, anthophyllite and chrysotile), alone or with the chemical benzo(a)pyrene (BP). Crocidolite was also tested with ultraviolet light. They counted colonies of cells with changed appearance, which the authors call transformation. Chrysotile was the most toxic. At 40 micrograms per dish, colony survival was 60% of untreated controls, and at 80 micrograms no colonies survived. At 40 micrograms per dish, each fiber alone produced rare transformations, about 0.2 to 0.5 per dish. Combined with BP, crocidolite raised transformation frequency 1.5- to 3.4-fold over the sum of each alone. The other three fibers gave similar enhancement. The differences between the combinations and BP alone were statistically significant (p less than 0.05). Crocidolite did not enhance transformation after ultraviolet light. The enhancement rose with dose for crocidolite and anthophyllite and was dose-independent for amosite. For chrysotile it rose up to 20 micrograms, then fell. The authors concluded this added experimental evidence that asbestos dust is a carcinogen. They suggested the fibers may help BP cross cell membranes.

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 transformation experiment in cultured hamster embryo cells
• Who was studied: Cultured embryo cells from 13-day-old Syrian hamster fetuses, seeded at 300 cells per 60-mm dish on a layer of X-irradiated feeder cells; usually 6 to 12 dishes per treatment
• Exposure: UICC standard reference crocidolite, amosite, anthophyllite and chrysotile 'B', at doses in micrograms per 20 cm2 dish (up to 80 micrograms). All four fibers were tested alone and combined with benzo(a)pyrene (1 microgram per ml of medium). Only crocidolite was tested with ultraviolet irradiation (3 J/m2).
• Main results:
  • Survival was measured as cloning efficiency relative to untreated control colonies.
  • Chrysotile was the most lethal fiber. At 40 micrograms per dish, colony survival was 60% relative to untreated controls, and at 80 micrograms no colonies survived (data not shown).
  • At 80 micrograms per dish, survival relative to untreated controls was about 90% with crocidolite or anthophyllite and 60% with amosite.
  • At 40 micrograms per dish, each fiber alone produced rare transformations. Crocidolite gave 0.2 to 0.3 transformations per dish, and the other three fibers gave 0.3 to 0.5 per dish.
  • Crocidolite alone gave 0.25, 0.25, 0.33 and 0.73 average transformations per dish at 10, 20, 40 and 80 micrograms.
  • BP alone gave a transformation frequency of 2 to 3%.
  • Crocidolite plus BP did not increase lethality but increased transformations per dish. The rise in transformation frequency was 1.5- to 3.4-fold over the sum of each treatment alone.
  • The differences in transformation frequency between crocidolite plus BP and BP alone were statistically significant (p less than 0.05 by Student's t test).
  • Chrysotile, amosite and anthophyllite combined with BP gave enhancement of transformation frequency similar to crocidolite.
  • Asbestos did not enhance transformation when combined with ultraviolet irradiation; crocidolite was the fiber tested with ultraviolet light.
  • At 80 micrograms, average transformations per dish were 5.4 with crocidolite plus BP versus 0.73 with crocidolite alone, and 3.5 versus 0.55 for anthophyllite.
  • For amosite the enhancement did not depend on dose: 1.3 transformations per dish with BP versus 0.58 with amosite alone.
  • For chrysotile the enhancement rose with dose up to 20 micrograms, giving 5.4 transformations per dish with BP versus 0.5 with chrysotile alone. At 40 micrograms the combination fell to 2.8 per dish.
  • Adding BP 24, 48 or 72 hours after asbestos gave transformation frequencies similar to adding it immediately (data not shown).
• The authors' conclusion: The authors concluded that the transformation results provided additional experimental evidence that asbestos dust is a carcinogen, and that all fiber types induced essentially the same transformation frequency. They suggested that BP's passage across cell membranes might be helped by its association with the fibers.

Topics

Medical terms in this study, explained in our Lexicon: Crocidolite, Anthophyllite, Amosite, Chrysotile, Carcinogenic.

Related studies

• Morphological transformation of Syrian hamster embryo cells induced by mineral fibres and the alleged enhancement of benzo[a]pyrene — S.O. Mikalsen, E. Rivedal, et al. (1988)
• Characterization of activated proto-oncogenes in chemically transformed Syrian hamster embryo cells — T.M. Gilmer, L.A. Annab, et al. (1988)
• 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 — A. Poole, R.C. Brown, et al. (1983)
• Detection of aneuploidy-inducing carcinogens in the Syrian hamster embryo (SHE) cell transformation assay — D.P. Gibson, M.J. Aardema, et al. (1995)
• 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)
• In vitro cytotoxicity and transforming potential of industrial carbon dust (fibers and particles) in syrian hamster embryo (SHE) cells — C. Darne, F. Terzetti, et al. (2010)

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