title: Effects of nicotine on antioxidant defense enzymes and RANKL expression in human periodontal ligament cells.
abstract: BACKGROUND
  This study examined the effects of nicotine on osteoblastic differentiation and the osteoclastogenesis regulatory molecules receptor activator of nuclear factor-kappa B ligand (RANKL) and osteoprotegerin (OPG). In addition, we investigated the mechanism by which nicotine induced antioxidant defense enzyme expression as a protective response.
  
  
  METHODS
  The expression of osteoblast markers, RANKL, OPG, and antioxidant defense enzymes were examined in nicotine-treated human periodontal ligament (PDL) cells by reverse transcription-polymerase chain reaction and Western blotting.
  
  
  RESULTS
  Nicotine treatment concomitantly downregulated the expression of OPG and osteoblastic differentiation markers, such as alkaline phosphatase, osteocalcin, and osteopontin, and upregulated the expression of RANKL. Nicotine induced the synthesis of the transcription factor NF-E2-related factor-2 (Nrf2) as well as a number of cellular antioxidants and phase II enzymes, such as heme oxygenase-1. Pretreatment with antioxidants inhibited the upregulation of RANKL, the downregulation of OPG expression, and cytotoxicity by nicotine in PDL cells.
  
  
  CONCLUSIONS
  Nicotine upregulated RANKL and antioxidant defense enzymes. These data suggest that Nrf2-mediated induction of cellular antioxidants and phase II enzymes could contribute to the cellular defense against nicotine-induced cytotoxicity and osteoclastic differentiation in PDL cells.
authors: Department of Oral and Maxillofacial Pathology, College of Dentistry, Wonkwang University, Iksan, South Korea.
authors: Hwa-Jeong
authors: HJ
authors: Lee
authors: Sung-Hee
authors: SH
authors: Pi
authors: Youngho
authors: Y
authors: Kim
authors: Hee-Soo
authors: HS
authors: Kim
authors: Sun-Ju
authors: SJ
authors: Kim
authors: Young-Suk
authors: YS
authors: Kim
authors: Suk-Keun
authors: SK
authors: Lee
authors: Eun-Cheol
authors: EC
authors: Kim
mesh_terms: D000469:Alkaline Phosphatase / Q000187:drug effects; D000975:Antioxidants / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D015536:Down-Regulation; D005293:Ferritins / Q000187:drug effects; D005721:Glutamate-Cysteine Ligase / Q000187:drug effects; D005979:Glutathione Peroxidase / Q000187:drug effects; D005982:Glutathione Transferase / Q000187:drug effects; D051547:Heme Oxygenase-1 / Q000187:drug effects; D006801:Humans; D020928:Mitogen-Activated Protein Kinases; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000187:drug effects; D051267:NF-E2-Related Factor 2 / Q000187:drug effects; D016328:NF-kappa B / Q000187:drug effects; D009538:Nicotine / Q000494:pharmacology* / Q000633:toxicity; D018722:Nicotinic Agonists / Q000494:pharmacology* / Q000633:toxicity; D010006:Osteoblasts / Q000187:drug effects; D015675:Osteocalcin / Q000187:drug effects; D010010:Osteoclasts / Q000187:drug effects; D053495:Osteopontin / Q000187:drug effects; D053244:Osteoprotegerin / Q000187:drug effects; D010513:Periodontal Ligament / Q000166:cytology / Q000187:drug effects*; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects; D053245:RANK Ligand / Q000187:drug effects*; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; D018722:Nicotinic Agonists; D053244:Osteoprotegerin; D053245:RANK Ligand; D015675:Osteocalcin; D053495:Osteopontin; D009538:Nicotine; D005293:Ferritins; D005979:Glutathione Peroxidase; D051547:Heme Oxygenase-1; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; D005982:Glutathione Transferase; D019869:Phosphatidylinositol 3-Kinases; D020928:Mitogen-Activated Protein Kinases; D000469:Alkaline Phosphatase; D005721:Glutamate-Cysteine Ligase