title: Cigarette smoke stimulates matrix metalloproteinase-2 activity via EGR-1 in human lung fibroblasts.
abstract: Cigarette smoking is a major risk factor for chronic obstructive pulmonary disease (COPD). Recent reports of increased matrix metalloproteinase-2 (MMP-2) in lungs of patients with emphysema support the paradigm of proteinase/antiproteinase imbalance in the pathogenesis of COPD. We sought to define the signaling pathways activated by smoke and to identify molecules responsible for emphysema-associated MMP-2 expression. In this study, we show that cigarette smoke extract (CSE) induced MMP-2 protein expression and increased MMP-2 gelatinase activity of normal lung fibroblasts. We previously identified a transcription factor, early growth response 1 (EGR-1), with robust expression in the lung tissues of patients with COPD compared with control smokers. Here, the treatment of fibroblasts with CSE resulted in marked induction of EGR-1 mRNA and protein in a dose- and time-dependent manner, accompanied by increased EGR-1 binding activity. CSE-induced MMP-2 mRNA and protein expression and activity were significantly inhibited using EGR-1 small interfering RNA (siRNA) or in Egr-1-null(-/-) mouse fibroblasts. Furthermore, we observed induction of membrane type 1 matrix metalloproteinase (MT1-MMP), which has an EGR-1-binding site on its promoter, in CSE-treated primary normal lung fibroblasts. The concomitant MT1-MMP expression and MMP-2 activation by CSE are inhibited by EGR-1 siRNA. Rapid activation of mitogen-activated protein kinases was observed in CSE-treated fibroblasts. Chemical inhibitors of ERK1/2 MAPK, but not of p38 and JNK, decreased CSE-induced EGR-1 protein expression and MMP-2 activity of fibroblasts. The identification that induction of MMP-2 and MT1-MMP by CSE from lung fibroblasts is EGR-1-dependent reveals a molecular mechanism for matrix remodeling in cigarette smoke-related emphysema.
authors.affiliation: University of Pittsburgh, Pulmonary, Allergy and Critical Care Medicine, MUH 628 NW, 3459 Fifth Ave., Pittsburgh, PA 15213, USA.
authors.forename: Wen
authors.initials: W
authors.lastname: Ning
authors.forename: Yingying
authors.initials: Y
authors.lastname: Dong
authors.forename: Jingxia
authors.initials: J
authors.lastname: Sun
authors.forename: Chaojun
authors.initials: C
authors.lastname: Li
authors.forename: Michael A
authors.initials: MA
authors.lastname: Matthay
authors.forename: Carol A
authors.initials: CA
authors.lastname: Feghali-Bostwick
authors.forename: Augustine M K
authors.initials: AM
authors.lastname: Choi
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D008168:Lung / Q000166:cytology / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008297:Male; D053511:Matrix Metalloproteinase 14 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D051379:Mice; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D012907:Smoking
chemical_list: D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D020778:Matrix Metalloproteinase 2; D053511:Matrix Metalloproteinase 14