The effect of BisGMA on cyclooxygenase-2 expression, PGE 2 production and cytotoxicity via reactive oxygen species- and MEK/ERK-dependent and -independent pathways Mei-Chi Chang a , Li-Deh Lin b , Chiu-Po Chan c , Hsiao-Hua Chang b , Lin-I Chen b, d , Hsueh-Jen Lin b, e , Hung-Wei Yeh b , Wan-Yu Tseng b , Po-Shuen Lin b , Chiu-Chun Lin f , Jiiang-Huei Jeng b, * a Biomedical Science Team, Chang Gung Institute of Technology, Taoyuan, Taiwan b Laboratory of Dental Pharmacology, Toxicology & Material Biocompatibility, Graduate Institute of Clinical Dentistry, National Taiwan University Medical College, National Taiwan University Hospital, Taipei, Taiwan c Department of Dentistry, Chang Gung Memorial Hospital, Taipei, Taiwan d Department of Dentistry, University of Adelaide, Australia e Dental Department, Show Chwan Memorial Hospital, Chang-Hua, Taiwan f Department of Dentistry, Chang Gung Memorial Hospital, Chang Gung University, Kaohsiung, Taiwan article info Article history: Received 8 February 2009 Accepted 23 April 2009 Available online 20 May 2009 Keywords: BisGMA Cytotoxicity Human dental pulp cells Prostaglandin Reactive oxygen species Signal transduction abstract After operative restoration, some monomers released from dentin bonding agents or composite resin may induce tissue inflammation and affect the vitality of dental pulp. Whether BisGMA, a major monomer of composite resin, may induce prostaglandin release and cytotoxicity to pulp cells and their mechanisms awaits investigation. We found that BisGMA induced cytotoxicity to human dental pulp cells at concentrations higher than 0.075 mM as analyzed by 3-(4,5-dimethyldiazol-2-yl)-2,5-diphenyl tetra- zolium bromide (MTT) assay. BisGMA (0.1 mM) also stimulated ERK phosphorylation, PGE 2 production, COX-2 mRNA and protein expression as well as ROS production (as indicated by an increase in cellular DCF fluorescence) in dental pulp cells. Catalase (500 and 1000 U/ml) and U0126 (10 and 20 mM, a MEK inhibitor) effectively prevented the BisGMA-induced ERK activation, PGE 2 production and COX-2 expression. Moreover, catalase can protect the pulp cells from BisGMA cytotoxicity, whereas aspirin and U0126 lacked of this protective activity. These results suggest that BisGMA released from composite resin may potentially affect the vitality of dental pulp and induce pulpal inflammation via stimulation of ROS production, MEK/ERK1/2 activation and subsequent COX-2 gene expression and PGE 2 production. Cytotoxicity of BisGMA to dental pulp cells is related to ROS production, but not directly mediated by MEK activation and PGE 2 production. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Resin modified glass ionomers and composite resins have been widely used for restoration of caries cavity or fractured tooth structure with or without dentin bonding agents for a long time [1]. However, considerable amounts of components may release from adhesive materials and composite resin even after polymerization. The major components leached from resin-based materials and adhesives included triethylene glycol dimethacrylate (TEGDMA), 2- hydroxyethyl methacrylate (HEMA), bisphenol-glycidylmethacry- late (BisGMA), urethane dimethacrylate (UDMA) and other addi- tives [2,3]. Different amounts of these monomers are found to be eluted from light-cured dental resins and resin composites into water, methanol, and 75% ethanol/water solution as analyzed by gas chromatography or/and high performance liquid chromatography [4–6]. They pose potential adverse systemic effects or damage to adjacent dental pulp and other oral tissues [3]. Restoration of deep caries cavity in human teeth with dentin bonding agents may induce evident cytotoxicity, pulpal inflammatory responses, delayed pulpal healing with failure of dentin bridge formation [7,8]. The levels of many inflammatory mediators such as prostaglandin E 2 (PGE 2 ), PGF 2a , 6-keto-PGF 1a , Interleukin-8 (IL-8) etc. are elevated during pulpal inflammation [9–11]. Dentin adhesives and their monomer contents have been shown to stimulate the expression of inflammatory mediators in oral epithelial cells and dental pulp cells * Corresponding author. Department of Endodontics, Laboratory of Pharma- cology, Toxicology & Material Biocompatibility, National Taiwan University Hospital, National Taiwan University Medical College, No. 1, Chang-Te Street, Taipei 100, Taiwan. Tel.: þ886 2 2312 3456; fax: þ886 2 2383 1346. E-mail addresses: jhjeng@ntu.edu.tw, benson86778231@yahoo.com.tw (J.-H. Jeng). Contents lists available at ScienceDirect Biomaterials journal homepage: www.elsevier.com/locate/biomaterials 0142-9612/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2009.04.034 Biomaterials 30 (2009) 4070–4077