title: Blocking TGF-β inhibits breast cancer cell invasiveness via ERK/S100A4 signal.
abstract: OBJECTIVE
  Targeted down-regulation of TGF-β expression inhibits invasion and metastasis in breast cancer cells. However, the mechanism that TGF-β functions by remains largely unknown. In the present study we report the mechanism of ERK1/2 dependant S100A4 regulation by TGF-β and its possible role in TGF-β-mediated tumour invasion in vitro.
  
  
  METHODS
  Small interfering RNA targeting TGF-β1 (TGF-β1 siRNA) were stably transfected into the breast cancer cell line MDA231. The TGF-β1 siRNA/9MDA231 cells were then treated with TGF-β1 (5 ng/ml) or treated with PD98059 (25 μM) or transfected into S100A4 siRNA before TGF-β1 treatment. The cells were used in several in vitro analyses, including migration, invasion, angiogenesis, and signaling assays. A wound-healing assay was used to determine migration of the cells in culture and a Boyden chamber transwell assay was used for invasion. In vitro angiogenesis studies using conditioned medium in HMEC-1 cells.
  
  
  RESULTS
  Inhibition of TGF-β1 expression by TGF-β1 siRNA transfection in MDA231 cells showed significant decrease migration, invasion and angiogenesis in vitro. TGF-β1 siRNA/MDA231 cells treated with 5 ng/ml TGF-β1 for 24 hs restored the invasive ability of TGF-β1 siRNA/MDA231 cells. TGF-β1 treatment could not increase migration, invasion and angiogenesis in TGF-β1 siRNA/MDA231 cells when treated with 25 μM PD98059 or transfected with S100A4 siRNA before TGF-β1 treatment. Analysis of TGF-β1 signaling pathways showed a decrease in p-ERK1/2 activation and an decrease in S100A4 expression. Interestingly, TGF-β1 regulated S100A4 via ERK1/2 signalling.
  
  
  CONCLUSIONS
  Our findings showed that blocking TGF-β inhibits breast cancer cell invasiveness, migration and angiogenesis via ERK/S100A4 signalling. Therapies targeting the TGF-β signaling pathway may be more effective to prevent progression in breast cancer.
authors.affiliation: Breast Surgery, Qilu Hospital, Shandong University, Jinan, China. yangqifeng7@163.com.
authors.forename: X G
authors.initials: XG
authors.lastname: Wang
authors.forename: Q
authors.initials: Q
authors.lastname: Meng
authors.forename: F M
authors.initials: FM
authors.lastname: Qi
authors.forename: Q F
authors.initials: QF
authors.lastname: Yang
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000517:prevention & control*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D009361:Neoplasm Invasiveness / Q000517:prevention & control*; D034741:RNA, Small Interfering / Q000008:administration & dosage; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins / Q000096:biosynthesis*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D053773:Transforming Growth Factor beta1 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis
chemical_list: D005419:Flavonoids; D034741:RNA, Small Interfering; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; D053773:Transforming Growth Factor beta1; C077591:S100A4 protein, human; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one