Effects of asbestos fibers on cell division, cell survival, and formation of thioguanine-resistant mutants in Chinese hamster ovary cells

Our plain-English summary of Effects of asbestos fibers on cell division, cell survival, and formation of thioguanine-resistant mutants in Chinese hamster ovary cells, by K. Kenne, S. Ljungquist, N.R. Ringertz (Environmental Research, 1986).

The study

• Authors: K. Kenne, S. Ljungquist, N.R. Ringertz
• Journal: Environmental Research
• Published: 1986;39(2):448-64
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The ability of crocidolite fibers to induce point mutations and mitotic abnormalities in Chinese hamster ovary (CHO) cells was examined in cell cultures. The purpose has been to study the possibilities for establishing in vitro test methods to quantify genetic damage induced by asbestos and other mineral fibers. Results obtained with the CHO/hypoxanthine guanine phosphoribosyl transferase system indicated that crocidolite fibers per se do not significantly increase the number of thioguanine-resistant mutants. Crocidolite fibers also failed to potentiate the mutagenicity of benzo[a]pyrene. Time-lapse cinematography and microscopy showed that asbestos (crocidolite) fibers were markedly cytotoxic. Among surviving cells some underwent abnormal cell divisions which resulted in multi- and micronucleate cells. Many cells that contained a few asbestos fibers, however, underwent mitosis and successfully formed two mononucleate daughter cells capable of further divisions. Individual, fiber-containing cells were examined by time-lapse television recordings for 4-5 days. During this time period some cells underwent six divisions and generated an almost normal number of daughter cells. Cells which contained fibers that were longer or equivalent to the diameter of the mitotic cell (20 microns), showed different forms of mitotic abnormalities. The frequency of multinucleate cells was drastically increased following exposure to asbestos fibers. Only rarely, however, did these cells divide to produce viable daughter cells capable of continued cell multiplication. The frequency of multinucleate cells was dependent on the dose of exposure to asbestos fibers and could possibly be used as an index of the degree of mitotic disturbances induced by mineral fibers.

In plain English

In this laboratory study, Chinese hamster ovary (CHO) cells grown in culture were exposed to crocidolite asbestos. The authors measured cell survival, the formation of thioguanine-resistant mutants (a test for point mutations at one gene), and whether crocidolite increased the mutation-causing effect of benzo[a]pyrene. They also filmed dividing cells by time-lapse video. Crocidolite was toxic to the cells: at 15 micrograms per 50-mm dish, only about 30% survived after 24 and 72 hours of exposure compared with untreated cells. No mutagenic effect was found at doses from 0 to 1500 micrograms per 90-mm dish, and at 50 or 100 micrograms per 90-mm dish mutants did not increase significantly over exposures of up to 3 days. There was no indication that crocidolite increased the mutagenicity of benzo[a]pyrene. Many fiber-containing cells divided successfully, but others divided abnormally. Cells with several nuclei became more frequent as the dose rose, and these cells rarely produced daughter cells that kept multiplying. The authors concluded that asbestos itself was not a mutagen in this test system. They suggested that counting multinucleate cells might be used to test how mineral fibers interfere with cell division.

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: mutation assay at the HGPRT gene, cytotoxicity tests, time-lapse video recordings and microscopy
• Who was studied: Cultured Chinese hamster ovary (CHO) cells, studied at the Department of Medical Cell Genetics, Medical Nobel Institute, Karolinska Institutet, Stockholm, Sweden (article received 1984, published 1986); no humans or animals
• Exposure: Crocidolite asbestos (UICC standard reference sample) at various doses and exposure times, alone or combined with benzo[a]pyrene plus a rat liver metabolizing mix (S9); ethyl methanesulfonate (EMS) was the positive control
• Main results:
  • Cytotoxicity over time (15 micrograms per 50-mm dish): no effect after 2 and 6 hours of exposure; after 24 and 72 hours only about 30% of cells survived compared with untreated cells
  • Cytotoxicity by dose: higher fiber concentrations were more toxic, but the lowest dose did not affect cell survival
  • No mutagenic effect (thioguanine-resistant mutants) was found for crocidolite in the dose range 0-1500 micrograms per 90-mm dish after a 2-hour treatment
  • With 50 or 100 micrograms crocidolite per 90-mm dish (45% and 60% of cells contained fibers after 2 hours), no significant increase in mutants was seen with exposure lasting up to 3 days
  • The positive control EMS (2-hour exposure) produced mutants at a frequency 10-20-fold higher than asbestos
  • In CHO cells there was no indication that crocidolite potentiated the mutagenicity of benzo[a]pyrene
  • Time-lapse recordings showed many fiber-containing cells completed division; of four filmed cells, Cell 31 showed a practically normal family tree, while Cells 5, 10 and 20 showed reduced growth and most of their daughter cells died
  • The frequency of multinucleate cells correlated with the asbestos dose; with a low dose over various times there was a slight increase over the background level
  • Multinucleate cells rarely underwent divisions producing cells able to keep multiplying
• The authors' conclusion: The authors concluded that asbestos in itself is not a mutagen in the CHO/HGPRT test system. They suggested that a test of the ability of mineral fibers to interfere with cell division could be based on their ability to induce multinucleate cells.
• Limitations the authors state:
  • At the highest dose, the standard deviation for mutants could not be given because reduced survival led to low recovery of mutants
  • Low asbestos doses tended to stimulate cell adhesion, causing an apparent increase in surviving cells
  • Some fibers remained after rinsing and were later taken up by the offspring of the original cells
  • Spontaneous multinucleation in control cultures occurred at a frequency too low to be recorded by the time-lapse technique

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, Mineral Fiber.

Related studies

• Amosite, chrysotile and crocidolite asbestos are mutagenic in Chinese hamster lung cells — S.L. Huang (1979)
• Cytotoxicity and multinucleate giant cell formation in Chinese hamster lung fibroblast caused by crocidolite and chrysotile — Y.C. Hong, S.S. Choi (1997)
• A comparison of the cytogenetic response to asbestos and glass fibre in Chinese hamster and human cell lines. Demonstration of growth inhibition in primary human fibroblasts — A.M. Sincock, J.D. Delhanty, et al. (1982)
• Increasing the therapeutic index of 5-fluorouracil and 6-thioguanine by targeting loss of MTAP in tumor cells — B. Tang, J.R. Testa, et al. (2012)
• Genotoxicity and cytotoxicity of multi-wall carbon nanotubes in cultured Chinese hamster lung cells in comparison with chrysotile A fibers — M. Asakura, T. Sasaki, et al. (2010)
• Effect of mineral dusts on metabolic cooperation between Chinese hamster V79 cells in vitro — M. Chamberlain (1983)

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