Crocidolite asbestos causes an induction of p53 and apoptosis in cultured A-549 lung carcinoma cells

Our plain-English summary of Crocidolite asbestos causes an induction of p53 and apoptosis in cultured A-549 lung carcinoma cells, by P. Pääkkö, M. Rämet, K. Vähäkangas, et al (Apoptosis, 1998).

The study

• Authors: P. Pääkkö, M. Rämet, K. Vähäkangas, N. Korpela, Y. Soini, S. Turunen, M. Jaworska, A. Gillissen
• Journal: Apoptosis
• Published: 1998;3(3):203-12
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A number of genotoxic chemicals and agents, such as benzo(a)pyrene and ultraviolet light, are able to induce nuclear accumulation of p53 protein. Usually, this response is transient and a consequence of stabilization of the wild-type p53 protein. After withdrawal of the exposure, the amount of p53 protein returns to a normal level within hours or a few days. We have studied the p53 response to the exposure of crocidolite asbestos in A-549 lung carcinoma cells using three different methods, i.e., p53 immunohistochemistry, Western blotting and metabolic labelling followed by p53 immunoprecipitation. With these techniques we demonstrate a dose-dependent p53 nuclear response to crocidolite exposure. The half-life of p53 protein in A-549 lung carcinoma cells cultured in serum-free media increased from 30 up to 80 min, and the protein reacted with a wild-type specific antibody suggesting that it was in a wild-type conformation. In situ 3'-end labelling of A-549 cells demonstrated a dose-dependent increase in apoptotic activity. Our data support the idea that increased apoptotic activity, induced by crocidolite, is mediated by p53.

In plain English

This was a laboratory study of cancer cells, not people. The authors exposed A-549 human lung carcinoma cells, which do not carry a p53 gene mutation, to UICC crocidolite asbestos for 24 hours at 0 to 50 micrograms per square centimetre of culture plate. Latex beads and titanium dioxide served as negative controls. Without crocidolite, about 1% of cell nuclei stained positive for the p53 protein. At 10 micrograms per square centimetre this rose sixfold, with no further increase at higher doses, probably because of toxicity, the authors said. Western blotting showed nuclear p53 rising with dose up to 2.5 micrograms per square centimetre. In exposed cells, labelled p53 took about 80 minutes to fall by half, versus 30 minutes in unexposed cells, and an antibody test suggested it had the normal (wild-type) form. Apoptosis (programmed cell death) rose up to 10-fold at 1.0 and 2.5 micrograms per square centimetre, with only a slight further increase at 5 or more. The control particles caused no such increases. The authors concluded that their data support the idea that crocidolite-induced apoptosis is mediated by p53. They noted the exposure was only short-term.

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 cell culture experiment (in vitro)
• Who was studied: A-549 human lung carcinoma cells, with OVCAR-3 ovarian adenocarcinoma cells (which carry a p53 mutation) used as a positive control; cell lines from the American Type Culture Collection
• Exposure: UICC crocidolite asbestos in serum-free medium for 24 hours, at 0, 0.1, 1.0, 2.5, 5.0, 10.0, 25 and 50 micrograms per square centimetre of tissue culture plate; latex beads and TiO2 as negative control particles
• Main results:
  • Unexposed A-549 cells in serum-free conditions: approximately 1% of nuclei were p53-positive
  • A-549 cells exposed to 10 micrograms crocidolite per square centimetre of culture plate: sixfold increase in the percentage of p53-positive nuclei
  • At 25 and 50 micrograms per square centimetre there was no further increase in the p53 response, which the authors attributed probably to toxic effects of crocidolite
  • Western blotting: dose-dependent increase in nuclear p53 protein up to 2.5 micrograms crocidolite per square centimetre of culture plate
  • Negative controls: neither latex beads nor TiO2 increased nuclear p53 protein
  • Labelled p53 fell to 50% of its maximum in approximately 80 min in crocidolite-exposed A-549 cells, compared with 30 min in unexposed control cells
  • The p53 protein reacted with a wild-type-specific antibody, which the authors said suggested a wild-type (non-mutated) conformation
  • At 1.0 and 2.5 micrograms crocidolite per square centimetre, the apoptotic index increased in a dose-response manner up to 10-fold
  • Crocidolite concentrations of 5 micrograms per square centimetre or more added only a slight further increase in the apoptotic index
  • Latex beads and TiO2 caused no increase in apoptotic activity in A-549 cells
• The authors' conclusion: The authors concluded that their data support the idea that the increased apoptotic activity induced by crocidolite is mediated by p53.
• Limitations the authors state:
  • The study involved only a short-term exposure of A-549 lung carcinoma cells to crocidolite; the authors suggest that long-term exposure studies are needed.

Topics

Medical terms in this study, explained in our Lexicon: Crocidolite, Apoptosis, Carcinoma, Immunohistochemistry.

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