Effect of Cell Cycle Growth Arrest on Global DNA Methylation Status in Human Lung Epithelial-like (A549) Cells

Abstract

Background: Decreased global DNA methylation have been previously shown in A549 cells exposed to prolonged hyperoxia. Because hyperoxia induces growth arrest in these cells, whether the status of global DNA methylation changed in response to cellular growth arrest was of interest. Materials and Methods: A549 cells were growth arrested at either the S- or G₂/M-phase of the cell cycle by exposure to resveratrol (25 μM), or colcemid (0.1 μg/ml) for 24 h. In addition, to determine the kinetics of hyperoxia-induced growth arrest, cells were exposed to either 1 day of normoxia or 1-5 days of hyperoxia. Results: The data indicate hyperoxia-induced G₂/M growth arrest after day 2 of exposure onwards. Moreover, 66.5% of cells were synchronized at the S-phase after exposure to resveratrol and 97% of them at the G₂/M-phase after exposure to colcemid. No changes in global DNA methylation status were observed in cells synchronized at either phase of the cell cycle. Conclusion: These findings indicate that global DNA methylation in A549 cells is not determined primarily by hyperoxia-induced cell cycle growth arrest.