title: Nitric oxide inhibits androgen receptor-mediated collagen production in human gingival fibroblasts.
abstract: Lin S-J, Lu H-K, Lee H-W, Chen Y-C, Li C-L, Wang L-F. Nitric oxide inhibits androgen receptor-mediated collagen production in human gingival fibroblasts. J Periodont Res 2012; 47: 701-710. © 2012 John Wiley & Sons A/S Background and Objective:  In our previous study, we found that flutamide [an androgen receptor (AR) antagonist] inhibited the up-regulation of collagen induced by interleukin (IL)-1β and/or nifedipine in gingival fibroblasts. The present study attempted to verify the role of nitric oxide (NO) in the IL-1β/nifedipine-AR pathway in gingival overgrowth.
  
  
  METHODS
  Confluent gingival fibroblasts derived from healthy individuals (n = 4) and those with dihydropyridine-induced gingival overgrowth (DIGO) (n = 6) were stimulated for 48 h with IL-1β (10 ng/mL), nifedipine (0.34 μm) or IL-1β + nifedipine. Gene and protein expression were analyzed with real-time RT-PCR and western blot analyses, respectively. Meanwhile, Sircol dye-binding and the Griess reagent were, respectively, used to detect the concentrations of total soluble collagen and nitrite in the medium.
  
  
  RESULTS
  IL-1β and nifedipine simultaneously up-regulated the expression of the AR and type-I collagen α1 [Colα1(I)] genes and the total collagen concentration in DIGO cells (p < 0.05). IL-1β strongly increased the expression of inducible nitric oxide synthase (iNOS) mRNA and the nitrite concentration in both healthy and DIGO cells (p < 0.05). However, co-administration of IL-1β and nifedipine largely abrogated the expression of iNOS mRNA and the nitrite concentration with the same treatment. Spearman's correlation coefficients revealed a positive correlation between the AR and total collagen (p < 0.001), but they both showed a negative correlation with iNOS expression and the NO concentration (p < 0.001). The iNOS inhibitor, 1400W, enhanced IL-1β-induced AR expression; furthermore, the NO donor, NONOate, diminished the expression of the AR to a similar extent in gingival fibroblasts derived from both healthy patients and DIGO patients (p < 0.05).
  
  
  CONCLUSIONS
  IL-1β-induced NO attenuated AR-mediated collagen production in human gingival fibroblasts. The iNOS/NO system down-regulated the axis of AR/Colα1(I) mRNA expression and the production of AR/total collagen proteins by DIGO cells.
authors.affiliation: Shin-Kong Wu Ho-Su Memorial Hospital, Taipei, Taiwan Periodontal Department, College of Oral Medicine, Taipei Medical University, Taipei, Taiwan.
authors.forename: S-J
authors.initials: SJ
authors.lastname: Lin
authors.forename: H-K
authors.initials: HK
authors.lastname: Lu
authors.forename: H-W
authors.initials: HW
authors.lastname: Lee
authors.forename: Y-C
authors.initials: YC
authors.lastname: Chen
authors.forename: C-L
authors.initials: CL
authors.lastname: Li
authors.forename: L-F
authors.initials: LF
authors.lastname: Wang
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D002478:Cells, Cultured; D024042:Collagen Type I / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D004095:Dihydropyridines / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D005881:Gingiva / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019214:Gingival Overgrowth / Q000139:chemically induced / Q000378:metabolism*; D006801:Humans; D053583:Interleukin-1beta / Q000378:metabolism; D008875:Middle Aged; D009543:Nifedipine / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D011944:Receptors, Androgen / Q000378:metabolism*; D018709:Statistics, Nonparametric
chemical_list: D024042:Collagen Type I; D004095:Dihydropyridines; D053583:Interleukin-1beta; D011944:Receptors, Androgen; D009569:Nitric Oxide; C038806:1,4-dihydropyridine; D052247:Nitric Oxide Synthase Type II; D009543:Nifedipine