Genotoxic potential of TEGDMA in oral epithelial cells

Objectives: Objective of the present study was to evaluate whether TEGDMA exhibits a genotoxic potential in human oral epithelial cells (OKF6/TERT2). Methods: TEGDMA-dependent cytotoxicity (0.025 to 5.0 mM), intracellular glutathione (GSH) content, and reactive oxygen species (ROS)-formation were assessed by means of fluorospectrophotometric analyses using propidium iodide, monobromobimane, and 2x,7x-dichlorodihydrofluorescein diacetate, respectively. All readings were performed with an FLX 800 microplate fluorescence reader (BioTec, Neufahrn, Germany) and were repeated at least 6 times with 6 replicates each. The alkaline comet assay ± human 8 hydroxyguanine DNA-glycosylase 1 (hOGG1), which is able to detect oxidative DNA-lesions, was used to determine the genotoxic potential of TEGDMA. One hundred cells were scored per sample. Results are expressed as median values of the olive tail moments (OTM) of 3 independent experiments. The Tukey ANOVA and Friedman test (p < 0.05) were applied for statistical analysis. Results: Incubation with TEGDMA (0.25 - 2.5 mM) resulted in significant GSH-depletion in OKF6/TERT2 cells in a time- and concentration-dependent manner (p<0.05). At 2.5 mM the GSH-content was reduced to 65.2% ± 7.3% (2 hrs), 50.9% ± 0.4% (4 hrs), and 56.3% ± 27.3% (6 hrs). There was no significant reduction in cell viability during 6 hrs of incubation and no ROS-formation was detected after 4 hrs of treatment with 0.25 - 5.0 mM TEGDMA. TEGDMA induced DNA-damage at concentrations from 0.5 - 2.5 mM (OTM between 8.5 - 11.5), which was most pronounced at 5.0 mM (OTM 94.3) (p<0.05). In negative control cultures the OTM ranged from 1.0 - 1.8. However, experiments with the hOGG1-modified comet-assay demonstrated that TEGDMA induced no increase in oxidative DNA-lesions. Conclusion: TEGDMA exhibits a genotoxic potential in human oral epithelial cells in vitro. However, the significant GSH-depletion neither induced intracellular ROS nor oxidative DNA base modifications