TNF-α induces matrix metalloproteinase-9-dependent soluble intercellular adhesion molecule-1 release via TRAF2-mediated MAPKs and NF-κB activation in osteoblast-like MC3T3-E1 cells

Background: matrix metalloproteinase-9 (mmp-9) has been shown to be induced by cytokines including tnf-α and may contribute to bone inflammatory diseases. however,the mechanisms underlying mmp-9 expression induced by tnf-α in mc3t3-e1 cells remain unclear. results: we applied gelatin zymography,western blot,rt-pcr,real-time pcr,selective pharmacological inhibitors of transcription (actinomycin d,act.d),translation (cycloheximide,chi),c-src (pp1),mek1/2 (u0126),p38 mapk (sb202190),jnk1/2 (sp600125),and nf-κb (bay11-7082),respective sirnas transfection,promoter assay,immunofluorescence staining,and elisa to investigate the mmp-9 expression and soluble icam-1 (sicam-1) release induced by tnf-α in mc3t3-e1 cells. here we demonstrated that tnf-α-induced mmp-9 expression was attenuated by act.d,chi,pp1,u0126,sb202190,sp600125,and bay11-7082,and by the transfection with sirnas for erk2,p38 mapk,and jnk2. tnf-α-stimulated tnfr1,traf2,and c-src complex formation was revealed by immunoprecipitation and western blot. furthermore,tnf-α-stimulated nf-κb phosphorylation and translocation were blocked by bay11-7082,but not by pp1,u0126,sb202190,or sp600125. tnf-α time-dependently induced mmp-9 promoter activity which was also inhibited by pp1,u0126,sb202190,sp600125,or bay11-7082. up-regulation of mmp-9 was associated with the release of sicam-1 into the cultured medium,which was attenuated by the pretreatment with mmp-2/9i,an mmp-9 inhibitor. conclusions: in this study,we demonstrated that tnf-α up-regulates mmp-9 expression via c-src,mapks,and nf-κb pathways. in addition,tnf-α-induced mmp-9 expression may contribute to the production of sicam-1 by mc3t3-e1 cells. the interplay between mmp-9 expression and sicam-1 release may exert an important role in the regulation of bone inflammatory diseases. © 2014 tsai et al.; licensee biomed central ltd.