title: Fibronectin increases matrix metalloproteinase 9 expression through activation of c-Fos via extracellular-regulated kinase and phosphatidylinositol 3-kinase pathways in human lung carcinoma cells.
abstract: Enhanced expression of matrix metalloproteinase-9 (MMP-9) is associated with human lung tumor invasion and/or metastasis. We have demonstrated that fibronectin (FN), a matrix glycoprotein, stimulates human non-small cell lung carcinoma (NSCLC) cell proliferation. The current study examines the effect of FN on MMP-9 expression in NSCLC cells. We show that FN increases MMP-9 protein, mRNA expression, and gelatinolytic activity in NSCLC cells. The integrin alpha5beta1 mediated the effects of FN because alpha5 small interfering RNA blocked FN-stimulated MMP-9 protein expression, and also abrogated FN-induced phosphorylation of ERK and phosphatidylinositol 3-kinase (PI3K) signals. The inhibitor of ERK, PD98095, and of PI3K, wortmannin, but not that of protein kinase A, H89, of Rho kinase, Y-27632, of mTOR, rapamycin, or of JNK, SP600125, prevented FN-induced MMP-9 gelatinolytic activity and gene expression. FN enhanced MMP-9 gene promoter activity; however, there was no response to FN in DNA constructs with an AP-1 site mutation. FN increased AP-1 DNA binding activity, and this was abrogated by cyclic AMP response element decoy oligonucleotides, which also diminished FN-induced MMP-9 promoter activity. FN increased the expression of the AP-1 subunit c-Fos protein, but not in the presence of PD98095 and wortmannin. The AP-1 inhibitor, nordihydroguaiaretic acid, and a c-Fos small interfering RNA eliminated the effect of FN on MMP-9 expression. This study indicates that FN, by binding to the integrin alpha5beta1 receptor, stimulates the expression of MMP-9 through increased AP-1/DNA binding and c-Fos protein expression via ERK and PI3K signaling pathways. The data unveils a novel mechanism by which FN could promote NSCLC cell invasion and metastasis.
authors.affiliation: Division of Pulmonary, Allergy and Critical Care Medicine, Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA. shan2@emory.edu
authors.forename: Shouwei
authors.initials: S
authors.lastname: Han
authors.forename: Jeff D
authors.initials: JD
authors.lastname: Ritzenthaler
authors.forename: Shanthi V
authors.initials: SV
authors.lastname: Sitaraman
authors.forename: Jesse
authors.initials: J
authors.lastname: Roman
mesh_terms: D002289:Carcinoma, Non-Small-Cell Lung / Q000201:enzymology* / Q000473:pathology; D045744:Cell Line, Tumor; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology*; D005353:Fibronectins / Q000502:physiology*; D006801:Humans; D008175:Lung Neoplasms / Q000201:enzymology* / Q000473:pathology; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis* / Q000235:genetics; D009361:Neoplasm Invasiveness / Q000473:pathology; D009362:Neoplasm Metastasis / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D014407:Tumor Cells, Cultured; D015854:Up-Regulation / Q000502:physiology
chemical_list: D005353:Fibronectins; D016760:Proto-Oncogene Proteins c-fos; D019869:Phosphatidylinositol 3-Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020780:Matrix Metalloproteinase 9