title: Tumor necrosis factor-alpha stimulates the expression of C-C chemokine ligand 2 gene in fibroblasts from the human nasal polyp through the pathways of mitogen-activated protein kinase.
abstract: BACKGROUND
  Recruitment of macrophages is crucial to the pathogenesis of the nasal polyp (NP) because this disease is believed to be inflammation related. Information regarding the expression of C-C chemokine ligand 2 (CCL2), an essential modulator of monocyte chemotaxis in nasal polyp fibroblasts (NPFs), remains unavailable. In this study, the effects of tumor necrosis factor (TNF)-a on CCL2 expression in NPFs and the signaling pathway involved were investigated.
  
  
  METHODS
  Primary cultures of NPFs were established from NPs. The expressions of CCL2, c-Fos, and c-Jun mRNAs in NPF after TNF-a stimulation were detected by Northern blot. Western blot was used to examine the activation of mitogen-activated protein kinase (MAPK) signaling pathways. Activator protein (AP) 1/DNA interactions were evaluated by electrophoretic mobility shift assay (EMSA).
  
  
  RESULTS
  Northern blot showed that TNF-alpha stimulated CCL2 gene expression in NPFs. Significant increase of B-Raf, phosphorated MAPK including mitogen-activated ERK-activate kinase (MEK)1/2, extracellular signal-related kinase 1/2, and p38 were detected by Western blot. c-Fos and c-Jun mRNAs were induced by TNF-alpha, and PD98059 (MEK inhibitor) and SB203580 (p38 inhibitor) abolished the up-regulation of c-Fos. EMSA revealed that TNF-a increased AP-1/DNA binding, and PD98059 and SB203580 attenuated this reaction, possibly via reducing c-Fos synthesis. PD98059 and curcunmin (AP-1 inhibitor) markedly suppressed the TNF-alpha-induced CCL2 expression, whereas the effect of SB203580 was less noted.
  
  
  CONCLUSIONS
  TNF-alpha induces CCL2 transcription in NPFs. B-Raf/MEK/ERK signaling cascade and to a less extent the p38 pathway are responsible for c-Fos activation and the subsequent AP-1/DNA interaction leading to CCL2 expression.
authors.affiliation: Department of Dentistry, National Taiwan University Hospital, Taiwan.
authors.forename: Sze-Kwan
authors.initials: SK
authors.lastname: Lin
authors.forename: Sang-Heng
authors.initials: SH
authors.lastname: Kok
authors.forename: Chia-Tung
authors.initials: CT
authors.lastname: Shun
authors.forename: Chi-Yuan
authors.initials: CY
authors.lastname: Hong
authors.forename: Chih-Chiang
authors.initials: CC
authors.lastname: Wang
authors.forename: Ming-Che
authors.initials: MC
authors.lastname: Hsu
authors.forename: Chia-Ming
authors.initials: CM
authors.lastname: Liu
mesh_terms: D015152:Blotting, Northern; D015153:Blotting, Western; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics* / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D015870:Gene Expression; D016762:Genes, fos; D016758:Genes, jun; D006801:Humans; D048728:MAP Kinase Kinase Kinase 1; D048730:MAP Kinase Kinase Kinase 2; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009298:Nasal Polyps / Q000235:genetics* / Q000378:metabolism*; D048493:Proto-Oncogene Proteins B-raf; D015398:Signal Transduction; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D018808:Transcription Factor AP-1; D014409:Tumor Necrosis Factor-alpha; D048493:Proto-Oncogene Proteins B-raf; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048728:MAP Kinase Kinase Kinase 1; D048730:MAP Kinase Kinase Kinase 2