title: Effects of nicotine on apoptosis in human gingival fibroblasts.
abstract: OBJECTIVE
  Cigarette smoke is a complex mixture of more than 4700 chemical compounds including free radicals and oxidants and it is a world widely known problem to health. Nicotine is the major compound of tobacco and known as the cause of gingivitis and periodontitis. It induces intracellular oxidative stress recognized as the important agent in the damage of biological molecules. The aim of this study is to clarify the cytotoxic pathway of nicotine in human gingival fibroblasts (HGFs).
  
  
  METHODS
  Human gingival fibroblasts stimulated by nicotine were used as an in vitro model. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to detect cell viability and reactive oxygen species (ROS) generation was assessed with 2,7-dichlorofluoroscein diacetate (DCF-DA). Morphological change was detected by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end labelling (TUNEL) assay, stained with 4,6-diamidino-2-phenylindole (DAPI). To delineate the roles of extracellular signal-regulated kinase (ERK), P38 and c-Jun N-terminal kinase (JNK), Western blot and caspase-3 (CASP3) activity assay were performed.
  
  
  RESULTS
  Exposure of the human gingival fibroblasts to nicotine reduced cell viability by time and dose dependent and increased the generation of ROS. It also showed morphological evidence of increased apoptosis, resulted in transient activation of JNK and ERK concomitant with activation of P38, and stimulated apoptosis as evidenced by CASP3 activation and Poly ADP ribose polymerase (PARP) cleavage.
  
  
  CONCLUSIONS
  These results suggest that nicotine induces apoptosis through the ROS generation and CASP3 dependent pathways in HGFs.
authors.affiliation: Department of Oral Pathology and Institute of Oral Biology, School of Dentistry, Kyung Hee University, Seoul 130-701, Republic of Korea.
authors.forename: S W
authors.initials: SW
authors.lastname: Kang
authors.forename: H J
authors.initials: HJ
authors.lastname: Park
authors.forename: J Y
authors.initials: JY
authors.lastname: Ban
authors.forename: J H
authors.initials: JH
authors.lastname: Chung
authors.forename: G S
authors.initials: GS
authors.lastname: Chun
authors.forename: J O
authors.initials: JO
authors.lastname: Cho
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000187:drug effects; D053453:Caspase 9 / Q000187:drug effects; D018929:Cell Culture Techniques; D002467:Cell Nucleus / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004396:Coloring Agents; D045304:Cytochromes c / Q000187:drug effects; D053938:DNA Fragmentation; D004305:Dose-Response Relationship, Drug; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects*; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005881:Gingiva / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D020287:In Situ Nick-End Labeling; D007211:Indoles; D048031:JNK Mitogen-Activated Protein Kinases / Q000187:drug effects; D009538:Nicotine / Q000633:toxicity*; D010766:Phosphorylation; D011065:Poly(ADP-ribose) Polymerases / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000032:analysis; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D051028:bcl-2-Associated X Protein / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects
chemical_list: C494826:BAX protein, human; D004396:Coloring Agents; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007211:Indoles; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D013844:Thiazoles; D051028:bcl-2-Associated X Protein; C029569:diacetyldichlorofluorescein; C007293:DAPI; D009538:Nicotine; D045304:Cytochromes c; D011065:Poly(ADP-ribose) Polymerases; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D053148:Caspase 3; D053453:Caspase 9; C022616:thiazolyl blue