title: Effect of Epigallocatechin-3-Gallate on PMA-Induced MUC5B Expression in Human Airway Epithelial Cells.
abstract: OBJECTIVE
  Among the inflammatory mediators, phorbol 12-myristate 13-acetate (PMA) is associated with the regulation of MUC5B expression in the airway epithelial cells. Epigallocatechin-3-gallate (EGCG) is the major component of green tea extract. The biological activity of EGCG includes reduction of cholesterol and antioxidant activity, as well as anti-inflammatory effect. However, the precise action mechanism of anti-inflammatory effect of EGCG in the airway epithelial cells has not been fully defined. This study investigates the effect and the brief signaling pathway of EGCG on PMA-induced MUC5B expression in the airway epithelial cells.
  
  
  METHODS
  In NCI-H292 airway epithelial cells, the effect and signaling pathway of EGCG on MUC5B expression were investigated using real-time polymerase chain reaction analysis, enzyme immunoassay, immunohistochemical analysis, gelatin zymography assay, and immunoblot analysis.
  
  
  RESULTS
  In NCI-H292 airway epithelial cells, PMA induced MUC5B expression, phosphorylation of p38 mitogen-activated protein kinase (MAPK), and matrix metalloproteinase-9 (MMP-9) expression and protein activity. EGCG significantly decreased PMA-induced MUC5B expression, phosphorylation of p38 MAPK, and MMP-9 expression and protein activity. SB203580 (p38 MAPK inhibitor) significantly decreased PMA-induced MMP-9 expression. In addition, SB203580 and MMP-9 I (MMP-9 inhibitor) significantly decreased PMA-induced MUC5B expression.
  
  
  CONCLUSIONS
  These results suggest that EGCG down-regulates PMA-induced MUC5B expression through the p38 MAPK dependent MMP-9 signaling pathway in human airway epithelial cells.
authors.affiliation: Department of Physiology, Yeungnam University College of Medicine, Daegu, Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Song
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Yeungnam University College of Medicine, Daegu, Korea.
authors.forename: Chang Hoon
authors.initials: CH
authors.lastname: Bae
authors.affiliation: Department of Physiology, Yeungnam University College of Medicine, Daegu, Korea.
authors.forename: Jong-Yeon
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Physiology, Yeungnam University College of Medicine, Daegu, Korea.
authors.forename: Yong-Woon
authors.initials: YW
authors.lastname: Kim
authors.affiliation: Department of Physiology, Yeungnam University College of Medicine, Daegu, Korea.
authors.forename: So-Young
authors.initials: SY
authors.lastname: Park
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Yeungnam University College of Medicine, Daegu, Korea.
authors.forename: Si-Youn
authors.initials: SY
authors.lastname: Song
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, Yeungnam University College of Medicine, Daegu, Korea. ; Regional Center for Respiratory Diseases, Yeungnam University Medical Center, Daegu, Korea.
authors.forename: Yong-Dae
authors.initials: YD
authors.lastname: Kim
keywords: Airway epithelial cell; Epigallocatechin-3-gallate; MUC5B; Matrix metalloproteinase-9; p38