Transfection of a manganese-containing superoxide dismutase gene into hamster tracheal epithelial cells ameliorates asbestos-mediated cytotoxicity

Our plain-English summary of Transfection of a manganese-containing superoxide dismutase gene into hamster tracheal epithelial cells ameliorates asbestos-mediated cytotoxicity, by B.T. Mossman, P. Surinrut, B.T. Brinton, et al (Free Radical Biology & Medicine, 1996).

The study

• Authors: B.T. Mossman, P. Surinrut, B.T. Brinton, J.P. Marsh, N.H. Heintz, B. Lindau-Shepard, J.B. Shaffer
• Journal: Free Radical Biology & Medicine
• Published: 1996;21(2):125-31
• Cited by: 31 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

To determine if overexpression of manganese-containing SOD (MnSOD) alters cell sensitivity to asbestos, an expression cassette containing murine MnSOD cDNA was cotransfected with pSV2neo, a plasmid conferring resistance to the antibiotic G418, into a diploid cell line of hamster tracheal epithelial (HTE) cells. Pools of G418-resistant transfectants were characterized by Southern and Northern blot analyses and enzyme activity assays. Although increases in MnSOD gene copies in individual cell pools ranged from approximately 7- to 86-fold in comparison to cells transfected with pSV2neo alone, steady-state levels of MnSOD mRNA were increased only by 1.4-to 2.3-fold. Despite modest increases in MnSOD mRNA, significant elevations in MnSOD enzyme activity were observed in pools of G418-resistant cells. MnSOD-transfected cell lines were more resistant to the cytotoxic effects of crocidolite asbestos using a sensitive colony-forming efficiency (CFE) assay. These data show that MnSOD has a direct role in cell defense against asbestos-induced cytotoxicity, an oxidant-dependent process.

In plain English

This was a laboratory experiment on cells grown in dishes, not a study of people or animals exposed in life. The authors inserted a mouse gene for manganese-containing superoxide dismutase (MnSOD), an antioxidant enzyme, into a cell line taken from the windpipe lining (tracheal epithelium) of a newborn golden Syrian hamster. They made five pools of altered cells and a control pool that received only a marker gene. Compared with the controls, the altered pools carried about 7 to 86 times more copies of the gene, but their MnSOD messenger RNA was only 1.4 to 2.3 times higher. MnSOD enzyme activity was significantly higher in all five pools. The cells were then exposed to crocidolite asbestos at 0.1 to 2 micrograms per square centimeter of dish. In all groups, asbestos reduced colony growth more at higher doses. All five MnSOD pools formed significantly more colonies than the controls, and the controls formed no surviving colonies at the highest dose. The authors concluded that MnSOD has a direct role in defending cells against asbestos-induced cell killing, which they described as an oxidant-dependent process.

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 culture experiment: gene transfection of a cell line, followed by a colony-forming efficiency assay to measure the cell-killing effect of asbestos
• Who was studied: A diploid hamster tracheal epithelial cell line (HTE B26 clone B) from a neonatal golden Syrian hamster, used at passages 40 to 50. Five pools of cells given the MnSOD gene (pools 1 to 5) were compared with a control pool given only the pSV2neo marker plasmid.
• Exposure: International Union Against Cancer reference sample of crocidolite asbestos, added to the culture medium at final concentrations of 0.1 to 2 micrograms per square centimeter of dish, with cells kept for a further 7 days
• Main results:
  • Compared with the pSV2neo control, MnSOD gene copy number was increased 86-fold in pool 5 (the highest) and 7- to 40-fold in pools 1 to 4
  • MnSOD messenger RNA levels in the transfected pools were only 1.4- to 2.3-fold higher than in pSV2neo control cells
  • CuZnSOD message levels were comparable in all cell pools (data not shown)
  • MnSOD enzyme activity was significantly increased (p less than 0.05) in all MnSOD-transfected pools compared with the pSV2neo control
  • Growth curves of the five MnSOD-transfected pools, the pSV2neo control and the parental HTE cells were comparable (data not shown)
  • In both the pSV2neo control and MnSOD-transfected pools, crocidolite asbestos inhibited cell growth in a dose-dependent manner
  • All MnSOD-transfected pools formed significantly more colonies at a given asbestos concentration than pSV2neo controls (p less than 0.05)
  • The pSV2neo control cells formed no viable colonies at the highest asbestos concentration tested (2 micrograms per square centimeter of dish)
• The authors' conclusion: The authors concluded that MnSOD has a direct role in cell defense against asbestos-induced cytotoxicity, which they described as an oxidant-dependent process

Topics

Medical terms in this study, explained in our Lexicon: Superoxide, Crocidolite.

Related studies

• Induction of manganese superoxide dismutase gene expression in bronchoepithelial cells after rockwool exposure — J. Marks-Konczalik, A. Gillissen, et al. (1998)
• Manganese superoxide dismutase in human pleural mesothelioma cell lines — V.L. Kinnula, P. Pietarinen-Runtti, et al. (1996)
• 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)
• Activation of protein kinase C by crocidolite asbestos in hamster tracheal epithelial cells — M. Perderiset, J.P. Marsh, et al. (1991)
• Asbestos induces nuclear factor kappa B (NF-kappa B) DNA-binding activity and NF-kappa B-dependent gene expression in tracheal epithelial cells — Y.M. Janssen, A. Barchowsky, et al. (1995)
• Active oxygen species mediate asbestos fiber uptake by tracheal epithelial cells — J. Hobson, J.L. Wright, et al. (1990)

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