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Glutathione level and genotoxicity in human oral keratinocytes exposed to TEGDMA
Author(s) -
Volk Joachim,
Leyhausen Gabriele,
Geurtsen Werner
Publication year - 2012
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.31960
Subject(s) - genotoxicity , comet assay , glutathione , propidium iodide , viability assay , reactive oxygen species , dna damage , oxidative stress , chemistry , dichlorofluorescein , microbiology and biotechnology , biochemistry , biophysics , apoptosis , toxicity , biology , programmed cell death , dna , organic chemistry , enzyme
Triethylene‐glycol dimethacrylate (TEGDMA) is an important matrix comonomer used in many resin‐modified dental materials. As the monomer‐polymer conversion of these biomaterials is up to 80% at best, TEGDMA may leach into the oral cavity and the pulp in millimolar concentrations. Objective of this study was to evaluate whether TEGDMA is genotoxic in immortalized human oral keratinocytes (OKF6/TERT2), for example, due to formation of oxidative DNA‐lesions. OKF6‐TERT2 cells were exposed to TEGDMA at concentrations ranging from 0.5 m M to 5.0 m M . Cell viability was analyzed by the fluorescent probe propidium iodide (PI), intracellular levels of reactive oxygen species (ROS) were measured by 2′,7′‐dichlorofluorescein diacetate, whereas glutathione concentrations (GSH) were read using monobromobimane. Genotoxicity was determined quantitatively by the alkaline comet assay. To explore the presence of oxidized bases that could be produced by oxidative events during short‐term treatment with TEGDMA, the 8‐hydroxyguanine DNA‐glycosylase 1 (hOGG1)‐modified comet assay was used. TEGDMA induced an early and rapid GSH‐depletion in a concentration‐dependent manner ( p < 0.05). A total of 5 m M TEGDMA reduced GSH to 57.8% ± 8.6% of control values already after 30 min. There was no significant reduction in cell viability during 6 h of incubation, and only moderate ROS‐formation was detected after 4 h of treatment with TEGDMA. But after 24 h, TEGDMA‐concentrations of ≥2.5 m M induced a significant reduction of total cell numbers and cells' viability. Furthermore, TEGDMA caused a concentration‐dependent DNA damage in OKF6/TERT2 cultures, which was not associated with a detectable formation of 8‐hydroxy‐2'‐deoxyguanosine (8‐OHdG) in the cellular genome. In conclusion, our results show that TEGDMA influences the intracellular redox metabolism and may exhibit pronounced cyto‐ and genotoxic effects in human immortalized oral keratinocytes. However, it may be concluded that oxidative stress is not causative for TEGDMA‐dependent genotoxicity in these cells. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 391–399, 2012.