Elevated transglutaminase-2 expression mediates fibrosis in areca quid chewing-associated oral submucocal fibrosis via reactive oxygen species generation.
OBJECTIVE
Transglutaminase-2 (TGM-2) protein is involved in the cross-linking of matrix proteins resulting in several fibrotic disorders and can be induced by reactive oxygen species (ROS). Little is known about its role in the development of oral submucocal fibrosis (OSF). Hence, we hypothesize that TGM-2 may have a role in the pathogenesis of areca quid chewing-associated OSF and arecoline, a major areca nut alkaloid, could regulate TGM-2 via ROS generation.


METHODS
Forty OSF specimens from areca quid chewing-associated OSF and ten normal buccal mucosa biopsy samples without areca quid chewing were analyzed by immunohistochemistry. The expression of TGM-2 from fibroblasts cultured from OSF and normal buccal mucosa was evaluated by Western blot. The effect of arecoline on normal buccal mucosa fibroblasts (BMFs) was used to elucidate whether TGM-2 expression could be affected by arecoline by using 2', 7'-dichlorofluorescein diacetate assay and Western blot. In addition, glutathione precursor N-acetyl-L-cysteine (NAC) and epigallocatechin-3 gallate (EGCG) were added to find the possible regulatory mechanisms.


RESULTS
TGM-2 expression was significantly higher in OSF specimens than normal specimens (p < 0.05). Fibroblasts derived from OSF were found to exhibit higher TGM-2 expression than BMFs in protein levels (p < 0.05). Arecoline significantly upregulated the intracellular ROS generation in a dose-dependent manner (p < 0.05). TGM-2 protein induced by arecoline was found in BMFs in a dose-dependent manner (p < 0.05). Treatment with NAC and EGCG markedly inhibited TGM-2 expression induced by arecoline (p < 0.05).


CONCLUSIONS
Our results suggest that TGM-2 expression is significantly upregulated in OSF tissues from areca quid chewers. Arecoline-upregulated TGM-2 expression may be mediated by ROS generation.


CONCLUSIONS
TGM-2 protein is upregulated in areca quid chewing-associated OSF. Using this in vitro model, antioxidants could inhibit arecoline-upregulated TGM-2 expression. NAC and EGCG may serve as a useful agent in controlling OSF.
School of Public Health, Chung Shan Medical University, Taichung, Taiwan.
Shiuan-Shinn
SS
Lee
School of Dentistry, Chung Shan Medical University, 110 Sec. 1, Chien-Kuo N. Rd, Taichung, Taiwan.
Yi-Juai
YJ
Chen
Department of Oral Pathology, Chung Shan Medical University Hospital, Taichung, Taiwan.
Chung-Hung
CH
Tsai
School of Dentistry, Chung Shan Medical University, 110 Sec. 1, Chien-Kuo N. Rd, Taichung, Taiwan.
Fu-Mei
FM
Huang
School of Dentistry, Chung Shan Medical University, 110 Sec. 1, Chien-Kuo N. Rd, Taichung, Taiwan. cyc@csmu.edu.tw.|Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan. cyc@csmu.edu.tw.
Yu-Chao
YC
Chang
D000111:Acetylcysteine / Q000494:pharmacology; D001114:Areca; D001115:Arecoline / Q000494:pharmacology; D015153:Blotting, Western; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D009914:Oral Submucous Fibrosis / Q000201:enzymology* / Q000517:prevention & control*; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D017382:Reactive Oxygen Species / Q000378:metabolism*; D011503:Transglutaminases / Q000378:metabolism*
D017382:Reactive Oxygen Species; D001115:Arecoline; D002392:Catechin; C045651:epigallocatechin gallate; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins; D000111:Acetylcysteine
Antioxidants; Arecoline; Oral submucocal fibrosis; Transglutaminase-2