title: TGF-β1 modulates the homeostasis between MMPs and MMP inhibitors through p38 MAPK and ERK1/2 in highly invasive breast cancer cells.
abstract: BACKGROUND
  Metastasis is the main factor responsible for death in breast cancer patients. Matrix metalloproteinases (MMPs) and their inhibitors, known as tissue inhibitors of MMPs (TIMPs), and the membrane-associated MMP inhibitor (RECK), are essential for the metastatic process. We have previously shown a positive correlation between MMPs and their inhibitors expression during breast cancer progression; however, the molecular mechanisms underlying this coordinate regulation remain unknown. In this report, we investigated whether TGF-β1 could be a common regulator for MMPs, TIMPs and RECK in human breast cancer cell models.
  
  
  METHODS
  The mRNA expression levels of TGF-β isoforms and their receptors were analyzed by qRT-PCR in a panel of five human breast cancer cell lines displaying different degrees of invasiveness and metastatic potential. The highly invasive MDA-MB-231 cell line was treated with different concentrations of recombinant TGF-β1 and also with pharmacological inhibitors of p38 MAPK and ERK1/2. The migratory and invasive potential of these treated cells were examined in vitro by transwell assays.
  
  
  RESULTS
  In general, TGF-β2, TβRI and TβRII are over-expressed in more aggressive cells, except for TβRI, which was also highly expressed in ZR-75-1 cells. In addition, TGF-β1-treated MDA-MB-231 cells presented significantly increased mRNA expression of MMP-2, MMP-9, MMP-14, TIMP-2 and RECK. TGF-β1 also increased TIMP-2, MMP-2 and MMP-9 protein levels but downregulated RECK expression. Furthermore, we analyzed the involvement of p38 MAPK and ERK1/2, representing two well established Smad-independent pathways, in the proposed mechanism. Inhibition of p38MAPK blocked TGF-β1-increased mRNA expression of all MMPs and MMP inhibitors analyzed, and prevented TGF-β1 upregulation of TIMP-2 and MMP-2 proteins. Moreover, ERK1/2 inhibition increased RECK and prevented the TGF-β1 induction of pro-MMP-9 and TIMP-2 proteins. TGF-β1-enhanced migration and invasion capacities were blocked by p38MAPK, ERK1/2 and MMP inhibitors.
  
  
  CONCLUSIONS
  Altogether, our results support that TGF-β1 modulates the mRNA and protein levels of MMPs (MMP-2 and MMP-9) as much as their inhibitors (TIMP-2 and RECK). Therefore, this cytokine plays a crucial role in breast cancer progression by modulating key elements of ECM homeostasis control. Thus, although the complexity of this signaling network, TGF-β1 still remains a promising target for breast cancer treatment.
authors.affiliation: Departamento de Bioquímica, Universidade de São Paulo, São Paulo, Brazil. mcsoga@iq.usp.br
authors.forename: Luciana R
authors.initials: LR
authors.lastname: Gomes
authors.forename: Letícia F
authors.initials: LF
authors.lastname: Terra
authors.forename: Rosângela Am
authors.initials: RA
authors.lastname: Wailemann
authors.forename: Leticia
authors.initials: L
authors.lastname: Labriola
authors.forename: Mari C
authors.initials: MC
authors.lastname: Sogayar
mesh_terms: D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000378:metabolism; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000494:pharmacology
chemical_list: D061965:Matrix Metalloproteinase Inhibitors; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D019714:Tissue Inhibitor of Metalloproteinases; D053773:Transforming Growth Factor beta1; D048051:p38 Mitogen-Activated Protein Kinases; D020782:Matrix Metalloproteinases