BACKGROUND & OBJECTIVE: Cigarette smoke exposure has been reported to induce DNA damage in a variety of cell types. This study was to investigate DNA damage and apoptosis in normal human bronchial epithelial cell line NHBE and lung carcinoma cell line SPC-A1 caused by cigarette smoke extract.METHODS: NHBE and SPC-A1 cells were incubated with different concentrations of cigarette smoke extract. Cell viability was evaluated by MTT assay. Fluorescence-labeled anti-histone gamma-H2AX polyclonal antibody was used to detect DNA double-strand breaks (DSBS) in chromatin. DNA damage was analyzed by flow cytometry. The expression of gamma-H2AX was detected by Western blot. Cigarette smoke extract-induced cell apoptosis was detected by sub G1 peak method and annexin V-FITC/propidium iodide (PI) staining assay. Cell morphology of DNA damage and apoptosis was observed by confocal laser microscopy.RESULTS: MTT assay results showed that cigarette smoke extract decreased the viability of NHBE and SPC-A1 cells in time-and concentration-dependent manners. Cigarette smoke extract induced DSBS in NHBE cells and SPC-A1 cells, and led to H2AX phosphorylation (denoted gamma-H2AX) in time-and concentration-dependent manners. The maximal value of gamma-H2AX was seen about 4 h after the treatment, and the value decreased subsequently, but did not reduce to a normal level. Cell apoptosis appeared about 12 h after DNA damage. Cigarette smoke extract also initiated the accumulation of gamma-H2AX in these cells, and cell apoptosis morphology was observed 4 h later.CONCLUSION: Cigarette smoke extract can induce DSBS and apoptosis in NHBE and SPC-A1 cells in time-and concentration-dependent manners.
Adenocarcinoma Apoptosis