Regulation of nicotine-induced cyclooxygenase-2 protein expression in human gingival fibroblasts.
OBJECTIVE
Activation of cyclooxygenase-2 (COX-2) expression by nicotine suggests a potential role for nicotine in the pathogenesis of smoking-associated periodontal disease. The aim of this study was to investigate whether chemical interactions can modulate nicotine-induced COX-2 expression in human gingival fibroblasts (HGF).


METHODS
Cytotoxicity was investigated by using lactate dehydrogenase leakage assays and Western blotting was used to assess COX-2 expression. Furthermore, buthionine sulfoximine (BSO; an intracellular glutathione synthesis inhibitor), 2-oxothiazolidine-4-carboxylic acid (OTZ; the precursor of cysteine), and PD98059 (extracellular signal-regulated protein kinase inhibitor) were added to search for the possible regulation mechanisms of nicotine-induced COX-2 expression.


RESULTS
Nicotine was found to elevate lactate dehydrogenase leakage in a dose-dependent manner (P<0.05). Treatment of HGF with nicotine was shown to mediate COX-2 protein expression. Pretreatment with OTZ decreased nicotine-induced COX-2 protein level by approximately 60 % (P<0.05). However, BSO enhanced nicotine-induced COX-2 protein level up to approximately 3-fold (P<0.05). Treatment of HGF with PD98059 decreased nicotine-induced COX-2 protein expression. In addition, nicotine induced extracellular signal-regulated protein kinase phosphorylation in a time-dependent manner (P<0.05).


CONCLUSIONS
Nicotine may play a significant role in the pathogenesis of cigarette smoking associated-periodontitis via the activation of COX-2 which is augmented by oxidative stress and mediated by extracellular signal-regulated protein kinase signaling.
Ho
Yung-Chuan
YC
School of Applied Chemistry, Chung Shan Medical University, Taichung, China.
Chang
Yu-Chao
YC
D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology*; D005419:Flavonoids / Q000494:pharmacology; D005881:Gingiva / Q000166:cytology / Q000201:enzymology*; D006801:Humans; D045022:Lactate Dehydrogenases / Q000378:metabolism; D009538:Nicotine / Q000633:toxicity*; D010766:Phosphorylation; D011761:Pyrrolidonecarboxylic Acid; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines
D005419:Flavonoids; D013844:Thiazoles; D053778:Thiazolidines; D019328:Buthionine Sulfoximine; D009538:Nicotine; D045022:Lactate Dehydrogenases; D051546:Cyclooxygenase 2; D048049:Extracellular Signal-Regulated MAP Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D011761:Pyrrolidonecarboxylic Acid; C029536:2-oxothiazolidine-4-carboxylic acid