Reversible cigarette smoke extract-induced DNA damage in human lung fibroblasts.

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.