Environmental Health Perspectives 105, Supplement 5, September 1997

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p53, Cip1, and Gadd153 Expression following Treatment of A549 Cells with Natural and Man-made Vitreous Fibers

Neil F. Johnson and Richard J. Jaramillo

Lovelace Respiratory Research Institute, Albuquerque, New Mexico

Abstract
DNA damage induced by chemicals and ionizing radiation is associated with the expression of negative regulators of the cell cycle. The arrest of cells in G1 and G2 phases of the cell cycle provides time for DNA repair. Asbestos fibers are carcinogenic when inhaled by both humans and animals; however, the mechanism by which the fibers exert their effect is unknown. This work was undertaken to determine whether the expression of DNA damage-inducible genes differs between crocidolite, a fiber positive for lung tumors, and JM 100 glass microfiber, which is negative for lung tumors when inhaled by rats. Temporal and dose-related expressions of p53, Cip1, and Gadd153 proteins were determined in cultured A549 cells treated with either Union Internationale Contre le Cancer crocidolite or JM 100 for 20 hr and cultured in fresh media. Immunolabeled cells were analyzed by flow cytometry, and the increased number of protein-expressing cells was determined by subtracting the expression in unexposed cells from exposed cells. Crocidolite induced the expression of all three proteins with a maximum expression after approximately 18 hr in fresh media. At a similar time point, JM 100 did not markedly induce the three proteins. Crocidolite also induced a dose-dependent increase in the number of cells in the G2 phase of the cell cycle. These results show that asbestos behaves like ionizing radiation and genotoxic chemicals by inducing proteins associated with DNA damage and cell-cycle arrest. The clear difference in response between crocidolite and JM 100 may help elucidate the mechanism of action of toxic and nontoxic fibers. -- Environ Health Perspect 105(Suppl 5):1143-1145 (1997)

Key words : p53, Cip1, Gadd153, asbestos, man-made vitreous fibers, A549 cells

This paper is based on a presentation at The Sixth International Meeting on the Toxicology of Natural and Man-Made Fibrous and Non-Fibrous Particles held 15-18 September 1996 in Lake Placid, New York. Manuscript received at EHP 26 March 1997; accepted 14 July 1997.
This research was sponsored by the Office of Health and Environmental Research, U.S. Department of Energy, under contract DE-AC04-76EV01013, and by National Institutes of Health grant ES 07665-01.
Address correspondence to Dr. N.F. Johnson, Lovelace Respiratory Research Institute, P.O. Box 5890, Albuquerque, NM 87185. Telephone: (505) 845-1189. Fax: (505) 845-1198. E-mail: njohnson@lrri.org
Abbreviations used: DPBS, Dulbecco's phosphate-buffered saline; NF- kappa B, nuclear factor kappa B; UICC, Union Internationale Contre le Cancer.

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Last Update: October 28, 1997