THE USE OF THE SINGLE-CELL GEL-ELECTROPHORESIS ASSAY IN DETECTING DNASINGLE-STRAND BREAKS IN LUNG-CELLS IN-VITRO

DNA single strand breaks (SSB) can be used as a biomarker of oxidant e xposure, and also as an indicator of the carcinogenicity/mutagenicity of a substance, The single cell gel electrophoresis (SCGE) assay is mo re sensitive and requires fewer cells compared to other techniques use d for detecting SSB, We examined the utility of using the SCGE assay f or human lung cells exposed to endogenous and exogenous oxidants. A hu man bronchial cell line (BEAS) was used as a model of airway epithelia l cells in this study, BEAS cells exposed to 0-50 mu M hydrogen peroxi de (H2O2) for 60 min at 4 degrees C exhibited a concentration-dependen t increase in SSB as determined by an increased DNA migration area in a gel undergoing electrophoresis. H2O2-induced increases in DNA SSB we re also demonstrated using cultured normal human tracheobronchial epit helial (NHBE) cells and human alveolar macrophages in a concentration response manner. BEAS cells were also exposed to air or ozone (O-3) on a Transwell filter without medium present apically. Cells exposed to O-3 at 0.1 or 0.4 ppm at 37 degrees C for up 120 min had a time- and c oncentration-dependent increase in SSB compared to air-exposed cells. NHBE cells exposed to 0.4 ppm O-3 (60 min) also had increased DNA SSB, Cells with H2O2-induced DNA SSB can be frozen and stored up to 4 week s without altering the original DNA SSB, These findings indicate that SCGE can be used to detect SSB in cultured lung cells, and has applica bility for detecting SSB in lung cells recovered from in vivo and in v itro exposures to oxidants. (C) 1996 Academic Press, Inc.