Abstract
BackgroundSince lung epithelial cells are constantly being exposed to reactive oxygen intermediates (ROIs), the alveolar surface is a major site of oxidative stress, and each cell type may respond differently to oxidative stress. We compared the extent of oxidative DNA damage with that of mitochondrial injury in lung epithelial cells at the single cell level.ResultDNA damage and mitochondrial injury were measured after oxidative stress in the SV-40 transformed lung epithelial cell line challenged with hydrogen peroxide (H2O2). Single cell analysis of DNA damage was determined by assessing the number of 8-oxo-2-deoxyguanosine (8-oxo-dG) positive cells, a marker of DNA modification, and the length of a comet tail. Mitochondrial membrane potential, ΔΨm, was determined using JC-1. A 1 h pulse of H2O2 induced small amounts of apoptosis (3%). 8-oxo-dG-positive cells and the length of the comet tail increased within 1 h of exposure to H2O2. The number of cells with reduced ΔΨm increased after the addition of H2O2 in a concentration-dependent manner. In spite of a continual loss of ΔΨm, DNA fragmentation was reduced 2 h after exposure to H2O2.ConclusionThe data suggest that SV-40 transformed lung epithelial cells are resistant to oxidative stress, showing that DNA damage can be dissociated from mitochondrial injury.
Highlights
Since lung epithelial cells are constantly being exposed to reactive oxygen intermediates (ROIs), the alveolar surface is a major site of oxidative stress, and each cell type may respond differently to oxidative stress
The aim of the current study was to investigate the susceptibility of DNA damage and mitochondrial injury caused by H2O2 in cultured SV-40 transformed lung epithelial cells, which may prove a useful in vitro model of the lung
Cell cycle analysis To compare the cell cycle effects of different culture conditions on starved BEAS-2B cell lines treated with H2O2, the number of proliferating cells and apoptotic cells were measured after culturing with growth factors (GF) or in GF-free medium
Summary
Since lung epithelial cells are constantly being exposed to reactive oxygen intermediates (ROIs), the alveolar surface is a major site of oxidative stress, and each cell type may respond differently to oxidative stress. Cigarette smoking can cause an acute inflammatory reaction in the lung, characterized by the accumulation and activation of leukocytes in vivo, producing ROIs and nitrogen species in high concentrations [3,4]. These different reactive species might be responsible for much of the tissue injuries and disease states associated with inflammation. Increased oxidative DNA damage, such as 8-hydroxyguanine formation in human lung tis-
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