DNA Damage And Apoptosis Of Human Airway Epithelial Cell Lines Treated By Cigarette Smoke Extract

Objective Cigarette smoke exposure has been reported to induce DNA damage in a variety of cell types. In the present study, we aim to investigate DNA damage and apoptosis in normal human bronchial epithelial Cells (NHBE) and lung carcinoma (SPC-A1) cells caused by cigarette smoke extract (CSE).Methods Human airway epithelial cell lines (NHBE and SPC-A1) incubated by different concentration of CSE were subjected to flow cytometric analysis of DNA damage. And the fluorescence labeled anti-histoneγ-H2AX polyclonal antibody was used to detect DNA double-strand breaks (DSBS) in chromatin. Cell viability was determined by MTT assay. Furthermore, CSE-induced apoptosis of Human airway epithelial cell lines were detected by subG1 peak method and annexin V-FITC/ propidium iodide (PI) staining assay. Cell morphology of DNA damage and apoptosis were observed by confocal laser microscopy.Results CSE can induce expression of DSBS in the indicated cells. Exposure of NHBE cells and SPC-A1 cells to CSE led to H2AX phosphorylation (denotedγ-H2AX) in both a time and dose dependent manner. The maximal rate ofγ-H2AX was seen during the initial 4h of cell treatment And it decreased subsequently, but it did not reduce to normal level. If the concentration of CSE was reduced (20 %),γ-H2AX continued to increase for up to 24h. Furthermore, after DNA damage would apoptosis in 12 hours. The MTT assay results showed that CSE decreased the cell viability of human airway epithelial cell lines in a time- and concentration- dependent manner. CSE also initiated the accumulation ofγ-H2AX in these cells, which was detected by confocal laser microscopy and after 4 hours the apoptosis morphology changes can be detected.Conclusion CSE can induce DSBS and apoptosis in these cells and there is a time- and concentration- dependent manner.γH2AX: a biomarker for DNA double-stranded breaks.