Abstract
Cigarette smoke contains thousands of chemicals, many of which may contribute to cytotoxicity and carcinogenesis. Using assays detecting DNA strand breaks (terminal transferase dUTP nick end labeling [TUNEL]) and DNA content (flow cytometry), we evaluated the genotoxic effect of cigarette smoke extract (CSE) on human fetal lung fibroblasts (HFL-1) cultured in three-dimensional collagen gels as well as in monolayer culture. When HFL-1 cells were exposed to CSE, DNA strand breaks were detected in most, as determined by TUNEL. This effect was dependent on CSE concentration, duration of CSE exposure, and the density of HFL-1 cells cast into the collagen gels. Buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis, significantly increased DNA damage induced by 1% CSE, and N-acetylcysteine, a glutathione precursor, blocked 5% CSE from inducing DNA damage. After CSE exposure, most cells were TUNEL-positive, but DNA quantification revealed no hypodiploid cells, indicating that apoptosis was not occur...