title: Matrix metalloproteinase expression in breast cancer.
abstract: BACKGROUND
  Matrix metalloproteinases (MMPs) have been implicated as possible mediators of invasion and metastasis in some cancers. Our objective was to investigate which MMPs were constitutively expressed in breast tumor cells versus those that could be up-regulated by a number of agents known to affect MMP expression in other cell systems.
  
  
  METHODS
  We evaluated expression of MMPs 1-16 in breast tumor cell lines MDA-MB-231, T47D, and MCF-7 using semiquantitative RT-PCR and gelatin zymography. Exposure to 12-O-tetradecanoylphorbal-3-acetate (TPA), concanavalin-A (Con-A), the fibronectin-mimetic peptide GRGDSP (RGD), extracellular matrix (ECM) components, and anti-integrin antibodies was used to test for possible MMP up-regulation. Mitogen-activated protein kinase inhibitors (MAPK-I) were used to evaluate signal transduction pathways and regulation of MMP expression.
  
  
  RESULTS
  MMPs 1, 2, 7-11, 13, 14, and 16 were constitutively expressed in some tumor cell lines but not in normal breast epithelial cells. Administration of TPA, Con-A, and RGD increased the expression of MMPs 1, 2, 9, and 10. No MMP up-regulation was seen in MDA-MB-231 or MCF-7 after exposure to ECM components or after exposure to anti-integrin antibodies. MAPK-I had no effect on constitutive MMP expression but reduced or abolished the TPA up-regulation of MMP-9 in MDA-MB-231 and MCF-7.
  
  
  CONCLUSIONS
  Breast tumor cell lines constitutively express a number of MMPs. Because MMP expression can be up-regulated by Con-A, the fibronectin-mimetic peptide RGD, and TPA while being susceptible to inhibition by MAPK antagonists, MAPK signaling appears to play a role in this expression.
authors.affiliation: Department of Surgery, Medical College of Ohio, 3065 Arlington Avenue, Toledo, OH 43614, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Bartsch
authors.forename: Edgar D
authors.initials: ED
authors.lastname: Staren
authors.forename: Hubert E
authors.initials: HE
authors.lastname: Appert
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D020782:Matrix Metalloproteinases / Q000096:biosynthesis* / Q000235:genetics*; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: D020782:Matrix Metalloproteinases