title: Non-steroidal anti-inflammatory drugs inhibit nitric oxide-induced apoptosis and dedifferentiation of articular chondrocytes independent of cyclooxygenase activity.
abstract: Nitric oxide (NO) causes apoptosis and dedifferentiation of articular chondrocytes by the modulation of extracellular signal-regulated kinase (ERK), p38 kinase, and protein kinase C (PKC) alpha and -zeta. In this study, we investigated the effects and mechanisms of non-steroidal anti-inflammatory drugs (NSAIDs), such as indomethacin, ketoprofen, ibuprofen, sulindac sulfide, and flurbiprofen, in NO-induced apoptosis and dedifferentiation of articular chondrocytes. We found that all of the examined NSAIDs inhibited apoptosis and dedifferentiation. NO production in chondrocytes caused activation of ERK-1/2 and p38 kinase, which oppositely regulate apoptosis and dedifferentiation. NO production also caused inhibition of PKCalpha and -zeta independent of and dependent on, respectively, p38 kinase, which is required for apoptosis and dedifferentiation. Among the signaling molecules modulated by NO, NSAIDs blocked NO-induced activation of p38 kinase, potentiated ERK activation, and blocked inhibition of PKCalpha and -zeta. NSAIDs also inhibited some of the apoptotic signaling that is downstream of p38 kinase and PKC, such as NFkappaB activation, p53 accumulation, and caspase-3 activation. The inhibitory effects of NSAIDs on apoptosis and dedifferentiation were independent of the inhibition of cyclooxygenase (COX)-2 and prostaglandin E(2) (PGE(2)) production, as evidenced by the observation that specific inhibition of COX-2 activity and PGE(2) production or exogenous PGE(2) did not affect NO-induced apoptosis and dedifferentiation. Taken together, our results indicate that NSAIDs block NO-induced apoptosis and dedifferentiation of articular chondrocytes by the modulation of ERK, p38 kinase, and PKCalpha and -zeta in a manner independent of their ability to inhibit COX-2 and PGE(2) production.
authors.affiliation: Department of Life Science, Kwangju Institute of Science and Technology; Buk-Gu, Gwangju 500-712, Korea.
authors.forename: Joo-Byoung
authors.initials: JB
authors.lastname: Yoon
authors.forename: Song-Ja
authors.initials: SJ
authors.lastname: Kim
authors.forename: Sang-Gu
authors.initials: SG
authors.lastname: Hwang
authors.forename: Sunghoe
authors.initials: S
authors.lastname: Chang
authors.forename: Shin-Sung
authors.initials: SS
authors.lastname: Kang
authors.forename: Jang-Soo
authors.initials: JS
authors.lastname: Chun
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002358:Cartilage, Articular / Q000166:cytology; D002454:Cell Differentiation / Q000187:drug effects; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D011817:Rabbits; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D011451:Prostaglandin-Endoperoxide Synthases; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases