Po-Shuen Lin1, Ru-Hsiu Cheng2, Mei-Chi Chang3, Jang-Jaer Lee4, Hsiao-Hua Chang1, Wei-Ling Huang5, Sin-Yuet Yeung6, Ya-Ching Chang7, Jiiang-Huei Jeng8. 1. School of Dentistry, College of Medicine, National Taiwan University Medical College and Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan. 2. School of Dentistry, Taipei Medical University, Taipei, Taiwan. 3. Biomedical Science Team, Chang Gung University of Science and Technology, Kwei-Shan, Taoyuan City, Taiwan; Department of Dentistry, Chang Gung Memorial Hospital, Taipei, Taiwan. Electronic address: mcchang@mail.cgust.edu.tw. 4. School of Dentistry, College of Medicine, National Taiwan University Medical College and Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan. Electronic address: leejj@ntuh.gov.tw. 5. Department of Dentistry, Chang Gung Memorial Hospital, Kaohsiung, Taiwan. 6. Department of Dentistry, Chang Gung Memorial Hospital, Taipei, Taiwan. 7. Department of Dentistry, Mackey Memorial Hospital, Taipei, Taiwan. 8. School of Dentistry, College of Medicine, National Taiwan University Medical College and Department of Dentistry, National Taiwan University Hospital, Taipei, Taiwan. Electronic address: jhjeng@ntu.edu.tw.
Abstract
BACKGROUND/PURPOSES: TGF-β1 is an important growth factor that may influence the odontoblast differentiation and matrix deposition in the reactionary/reparative dentinogenesis to dental caries or other tooth injuries. TGF-β1 exerts its effects through various signaling pathways, such as Smads and MAPKs. Cyclooxygenase-2 (COX-2) is a membrane-associated enzyme that produces prostaglandin E2 (PGE2) at sites of pulpal injury and inflammation, which leads to tissue swelling, redness and pain. The purposes of this study were to investigate the differential signal transduction pathways of TGF-β1 that mediate COX-2 stimulation and PGE2 production in dental pulp cells. METHODS: Pulp cells were exposed to TGF-β1 with/without SB431542 (an ALK5/Smad2 inhibitor) and U0126 (a MEK/ERK inhibitor). MTT assay was used to estimate cell viability. Enzyme-linked immunosorbent assay (ELISA) was used for measurement of PGE2 levels. RT-PCR and western blot were used to determined COX-2 mRNA and protein, respectively. RESULTS: Exposure to TGF-β1 (1-10 ng/ml) increased the COX-2 mRNA and protein level of cultured pulp cells. Exposure to TGF-β1 (0.1-10 ng/mL) significantly stimulated PGE2 production of dental pulp cells. Under the pretreatment of SB431542, the stimulatory effect of TGF-β1 on COX-2 level of pulp cells was inhibited. Similarly, U0126 also partly inhibited the TGF-β1-induced COX-2 expression. CONCLUSION: TGF-β1 increased the COX-2 and PGE2 level of cultured pulp cells. The effect of TGF-β1 on COX-2 protein expression was associated with ALK5/Smad2/3 and MEK/ERK pathways. These events are important in the early inflammation, repair and regeneration of dental pulp in response to injury.
BACKGROUND/PURPOSES: TGF-β1 is an important growth factor that may influence the odontoblast differentiation and matrix deposition in the reactionary/reparative dentinogenesis to dental caries or other tooth injuries. TGF-β1 exerts its effects through various signaling pathways, such as Smads and MAPKs. Cyclooxygenase-2 (COX-2) is a membrane-associated enzyme that produces prostaglandin E2 (PGE2) at sites of pulpal injury and inflammation, which leads to tissue swelling, redness and pain. The purposes of this study were to investigate the differential signal transduction pathways of TGF-β1 that mediate COX-2 stimulation and PGE2 production in dental pulp cells. METHODS: Pulp cells were exposed to TGF-β1 with/without SB431542 (an ALK5/Smad2 inhibitor) and U0126 (a MEK/ERK inhibitor). MTT assay was used to estimate cell viability. Enzyme-linked immunosorbent assay (ELISA) was used for measurement of PGE2 levels. RT-PCR and western blot were used to determined COX-2 mRNA and protein, respectively. RESULTS: Exposure to TGF-β1 (1-10 ng/ml) increased the COX-2 mRNA and protein level of cultured pulp cells. Exposure to TGF-β1 (0.1-10 ng/mL) significantly stimulated PGE2 production of dental pulp cells. Under the pretreatment of SB431542, the stimulatory effect of TGF-β1 on COX-2 level of pulp cells was inhibited. Similarly, U0126 also partly inhibited the TGF-β1-induced COX-2 expression. CONCLUSION: TGF-β1 increased the COX-2 and PGE2 level of cultured pulp cells. The effect of TGF-β1 on COX-2 protein expression was associated with ALK5/Smad2/3 and MEK/ERK pathways. These events are important in the early inflammation, repair and regeneration of dental pulp in response to injury.