Effects of crocidolite and chrysotile asbestos on cellular uptake and metabolism of benzo(a)pyrene in hamster tracheal epithelial cells

Our plain-English summary of Effects of crocidolite and chrysotile asbestos on cellular uptake and metabolism of benzo(a)pyrene in hamster tracheal epithelial cells, by B.T. Mossman, A. Eastman, J.M. Landesman, et al (Environmental Health Perspectives, 1983).

The study

• Authors: B.T. Mossman, A. Eastman, J.M. Landesman, E. Bresnick
• Journal: Environmental Health Perspectives
• Published: 1983;51:331-5
• Cited by: 51 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The incidence of bronchogenic carcinoma is increased substantially in asbestos workers who smoke. We used several approaches to determine possible mechanisms of synergism at the cellular level between asbestos and the polycyclic aromatic hydrocarbon (PAH), benzo(a)pyrene (BaP), a chemical carcinogen in cigarette smoke. Specifically, we hypothesized that cellular uptake and metabolism of BaP might be facilitated when the hydrocarbon was coated on asbestos. In addition, we were interested in whether asbestos, alone or in combination with BaP, caused single strand breakage of DNA in epithelial cells of the airway. UICC reference samples of crocidolite and chrysotile were coated with 3H-BaP before their addition to monolayers of hamster tracheal epithelial cells. In comparative studies, 3H-BaP at identical amounts was added to cells in culture medium. At intervals thereafter, uptake of BaP by cells was documented by scintillation spectrometry and by autoradiography. In addition, cells and media were assayed by use of high pressure liquid chromatography (HPLC) to demonstrate the water-soluble metabolites of BaP. The integrity of DNA was monitored by alkaline elution at intervals after exposure of tracheal cells to various concentrations of asbestos, BaP and BaP-coated asbestos. A rapid transfer of BaP to cells occurred after addition of BaP-coated asbestos to cultures. When BaP was adsorbed to both types of fibers before their addition to cultures, 70% of the total BaP introduced entered the cell within 1 hr; 50% remained intracellular after 8 hr. In contrast, if identical amounts of BaP were added directly to medium, an initial influx of 20% was observed and cells retained only 5% of the initial amount at 8 hr.(ABSTRACT TRUNCATED AT 250 WORDS)

In plain English

This was a laboratory study using cultured hamster airway-lining cells, not people. The authors coated UICC reference samples of crocidolite and chrysotile asbestos with radioactively labeled benzo(a)pyrene (BaP), a cancer-causing chemical in cigarette smoke. They added the coated fibers to the cells and compared this with adding the same amount of BaP directly to the culture medium. When BaP was carried on asbestos, about 68 to 70% of it entered the cells within 1 hour, and 42% (crocidolite) or 38% (chrysotile) was still inside at 8 hours. When BaP was simply dissolved in the medium, 22% entered at 1 hour and 5% remained at 8 hours. Breakdown products of BaP were consistently but not markedly lower with coated asbestos. Neither fiber type, alone or coated with BaP at the doses tested, caused detectable DNA strand breaks. The authors concluded that asbestos may help carry such chemicals into airway cells and keep them there, which might be a way asbestos contributes to lung cancer.

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 (laboratory cell culture) experiment
• Who was studied: HTE-B, a nontumorigenic cell line isolated and cloned from neonatal hamster tracheal (windpipe) epithelium; passages 40-50 were used
• Exposure: UICC reference samples of crocidolite and chrysotile asbestos coated with radiolabeled benzo(a)pyrene (BaP), compared with BaP dissolved in medium and with uncoated asbestos at nontoxic concentrations
• Main results:
  • BaP delivered on asbestos: cellular content was 68% (crocidolite) and 70% (chrysotile) of the BaP introduced at 1 hr, and 42% and 38% at 8 hr (Table 1); the text gives approximately 70% at 1 hr and 50% at 8 hr
  • BaP dissolved in medium: about 20% (22% in Table 1) entered cells at 1 hr and only 5% remained at 8 hr
  • Water-soluble BaP metabolites were almost undetectable at 1 hr and rose to 40-50% of BaP applied by 8 hr; with BaP-coated asbestos, metabolite amounts were consistently but not markedly lower
  • Crocidolite and chrysotile at nontoxic concentrations did not cause DNA breakage detectable by alkaline elution
  • No increase in DNA breakage was seen with BaP at 2 to 3 x 10 to the minus 6 M, whether used alone or coated on asbestos; these were the maximum amounts that could be coated on nontoxic amounts of asbestos
• The authors' conclusion: The authors concluded that asbestos not only helps transfer polycyclic aromatic hydrocarbons such as BaP into airway cells but also increases how long the cells retain them, and that these processes might be mechanisms of asbestos-induced (co)carcinogenesis

Topics

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

Medical terms in this study, explained in our Lexicon: Crocidolite, Chrysotile, Bronchogenic Carcinoma, UICC.

Related studies

• 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)
• Asbestos and benzo[a]pyrene act synergistically to induce squamous metaplasia and incorporation of [3H]thymidine in hamster tracheal epithelium — B.T. Mossman, A. Eastman, et al. (1984)
• 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)
• Enhancement of benzo[a]pyrene mutagenicity by chrysotile asbestos in rat liver epithelial cells — B. Reiss, C. Tong, et al. (1983)
• Activation of protein kinase C by crocidolite asbestos in hamster tracheal epithelial cells — M. Perderiset, J.P. Marsh, et al. (1991)
• Effect of chrysotile asbestos and silica on the microsomal metabolism of benzo(a)pyrene — C. Kandaswami, P.J. O'Brien (1983)

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