title: NADPH oxidase 4 is involved in the triethylene glycol dimethacrylate-induced reactive oxygen species and apoptosis in human embryonic palatal mesenchymal and dental pulp cells.
abstract: OBJECTIVE
  Triethylene glycol dimethacrylate (TEGDMA) is a common component of resin-based dental composites and endodontic sealers. TEGDMA induces apoptosis in several types of cells. However, the mechanisms are not completely understood. The aim of this study was to investigate the mechanisms underlying TEGDMA-induced apoptosis in human embryonic palatal mesenchymal (HEPM) pre-osteoblasts and primary human dental pulp (HDP) cells.
  
  
  METHODS
  Cell viability was examined after TEGDMA treatment. Cell cycle progression was checked by flow cytometry. Apoptotic cells were evaluated using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling assay and visualized by fluorescence microscopy. Western blot analyses were performed to determine expressions of apoptosis-related proteins. The production of reactive oxygen species (ROS) was detected using flow cytometry. NADPH oxidase 4 (NOX4) expression levels were investigated using real-time quantitative polymerase chain reaction and Western blot analyses.
  
  
  RESULTS
  TEGDMA increased cytosol cytochrome c levels and activated caspase-9 in HEPM and HDP cells. TEGDMA decreased the expression of anti-apoptotic protein Bcl-XL. TEGDMA-induced apoptosis was inhibited by caspase-9-specific inhibitor, anti-oxidants, NOX inhibitor, NOX4 inhibitor, and NOX4 small interfering RNA (siRNA). TEGDMA increased ROS production and upregulated NOX4 mRNA and protein expression. TEGDMA-induced intracellular ROS production was inhibited by NOX inhibitor and NOX4 inhibitor.
  
  
  CONCLUSIONS
  We demonstrate significant involvement of NOX4 in the TEGDMA-induced ROS. NOX4-derived ROS subsequently induces mitochondrial cytochrome c release leading to apoptosis through activation of the intrinsic apoptotic pathway.
  
  
  CONCLUSIONS
  NOX4 may be a potential target for strategies to prevent or ameliorate the TEGDMA-induced toxicity in HEPM and HDP cells.
authors.affiliation: School of Dentistry, College of Medicine and Department of Dentistry, National Taiwan University Hospital, National Taiwan University Medical Center, 1 Chang-Te Street, Taipei, 10048, Taiwan.
authors.forename: Cheng-Chang
authors.initials: CC
authors.lastname: Yeh
authors.forename: Jenny Zwei-Chieng
authors.initials: JZ
authors.lastname: Chang
authors.forename: Wan-Hsien
authors.initials: WH
authors.lastname: Yang
authors.forename: Hao-Hueng
authors.initials: HH
authors.lastname: Chang
authors.forename: Eddie Hsiang-Hua
authors.initials: EH
authors.lastname: Lai
authors.forename: Mark Yen-Ping
authors.initials: MY
authors.lastname: Kuo
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002453:Cell Cycle; D002470:Cell Survival; D003782:Dental Pulp / Q000166:cytology*; D005434:Flow Cytometry; D006801:Humans; D020287:In Situ Nick-End Labeling; D000074663:NADPH Oxidase 4 / Q000502:physiology*; D010006:Osteoblasts / Q000187:drug effects*; D010159:Palate / Q000166:cytology* / Q000196:embryology; D011092:Polyethylene Glycols / Q000494:pharmacology*; D011109:Polymethacrylic Acids / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D011109:Polymethacrylic Acids; D017382:Reactive Oxygen Species; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D000074663:NADPH Oxidase 4