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The regulation of cytotoxicity and cyclooxygenase-2 expression by 2-hydroxy-ethyl methacrylate in human osteoblasts are related to intracellular glutathione levels.

AIM
To investigate the effects of 2-hydroxy-ethyl methacrylate (HEMA) on cytotoxicity and cyclooxygenase-2 (COX-2) protein expression in human osteoblasts.


METHODOLOGY
Cytotoxicity was judged using an Alamar Blue reduction assay on human osteoblast cell line U2OS. Western blot was used to evaluate the expression of COX-2 protein by HEMA. To determine whether glutathione (GSH) levels were important in cytotoxicity and COX-2 expression of HEMA, cells were pre-treated with the GSH precursor, 2-oxothiazolidine-4-carboxylic acid (OTZ), to boost thiol levels, or buthionine sulfoximine (BSO) to deplete GSH. Paired Student's t-tests were applied for the statistical analysis of the results.


RESULTS
HEMA demonstrated a cytotoxic effect to U2OS cells in a dose-dependent manner (P < 0.05). The 50% inhibition concentration of HEMA was approximately 3 mmol L(-1) . HEMA was found to induce COX-2 protein expression in U2OS cells (P < 0.05). The addition of OTZ acted as a protective effect on HEMA-induced cytotoxicity and COX-2 expression (P < 0.05). In contrast, the addition of BSO enhanced HEMA-induced cytotoxicity and COX-2 expression (P < 0.05).


CONCLUSION
Taken together, the levels of HEMA that were tested inhibited cell growth on U2OS cells. HEMA has a significant potential for periapical toxicity. The activation of COX-2 protein expression may be one of the mechanisms of HEMA-induced periapical inflammation. These inhibitory effects were associated with intracellular GSH levels.