title: Hydrogen peroxide induces apoptosis in human dental pulp cells via caspase-9 dependent pathway.
abstract: BACKGROUND
  Reactive oxygen species are a group of metabolic intermediates produced during oxidative metabolism in eukaryotic cells. They include superoxide anion (O2(-)), hydrogen peroxide (H2O2), hydroxyl radical (·OH), and (1)O2. Of these intermediates, H2O2 is the most stable. Dental pulp cells can be invaded by tooth bleaching, laser radiation, and dental materials. This can influence the intracellular level of reactive oxygen species. Apoptosis, which is the best-known form of programmed cell death, is pivotal to tissue development and regeneration. Little information is available regarding the relationship between H2O2 and apoptosis of human dental pulp cells (hDPCs). The purpose of this study was to investigate whether H2O2 can induce apoptosis in hDPCs and its signaling way.
  
  
  METHODS
  HDPCs were obtained by using a modified tissue explant technique in vitro and cultured at 37°C, 20% O2 (5% CO2, 95% air) in Dulbecco modified Eagle medium. Cell viability was investigated by methyl-thiazol-tetrazolium assay. Cell apoptosis was detected by using the annexin V-fluorescein isothiocyanate/propidium iodide apoptosis assay and flow cytometry. Expression of activated caspase-3, cleaved caspase-9, and β-actin was analyzed by using Western blot.
  
  
  RESULTS
  Cell viability of hDPCs decreased more in treated groups than in the control group from days 1 to 7. The relative number of apoptotic cells and the expression of activated caspase-3 and cleaved caspase-9 were much higher in groups exposed to 20 and 50 μmol/L H2O2.
  
  
  CONCLUSIONS
  These results imply that low concentrations of H2O2 are cytotoxic to hDPCs and induce apoptosis in hDPCs in a caspase-9-dependent way.
authors: Department of General Dentistry, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Key Laboratory of Stomatology, Shanghai, China.
authors: Tian-tian
authors: TT
authors: Wu
authors: Li-fen
authors: LF
authors: Li
authors: Rong
authors: R
authors: Du
authors: Long
authors: L
authors: Jiang
authors: Ya-Qin
authors: YQ
authors: Zhu
mesh_terms: D000199:Actins / Q000032:analysis / Q000187:drug effects; D000293:Adolescent; D000328:Adult; D017304:Annexin A5; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D053148:Caspase 3 / Q000032:analysis / Q000187:drug effects; D053453:Caspase 9 / Q000032:analysis / Q000187:drug effects*; D018929:Cell Culture Techniques; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004396:Coloring Agents; D003782:Dental Pulp / Q000166:cytology / Q000187:drug effects*; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives; D005456:Fluorescent Dyes; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology* / Q000633:toxicity; D016877:Oxidants / Q000494:pharmacology* / Q000633:toxicity; D011419:Propidium; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D055815:Young Adult
chemical_list: D000199:Actins; D017304:Annexin A5; D004396:Coloring Agents; C492760:FITC-annexin A5; D005456:Fluorescent Dyes; D016877:Oxidants; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; D011419:Propidium; D006861:Hydrogen Peroxide; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; C022616:thiazolyl blue; D016650:Fluorescein-5-isothiocyanate
keywords: Apoptosis; ROS; dental pulp cells