title: The endothelin A receptor and epidermal growth factor receptor signaling converge on β-catenin to promote ovarian cancer metastasis.
abstract: OBJECTIVE
  Endothelin A receptor (ET(A)R) and epidermal growth factor receptor (EGFR) cross-talk enhances the metastatic potential of epithelial ovarian cancer (EOC) cells activating different pathways, including β-catenin signalling. Here, we evaluated β-catenin as one of ET(A)R/EGFR downstream pathway in the invasive behaviour of EOC cells and their therapeutic potential to co-target ET(A)R and EGFR.
  
  
  METHODS
  The phosphorylation status and interactions of different proteins were analysed by immunoblotting and immunoprecipitation. Reporter activity and RT-PCR was used for evaluation of β-catenin transcriptional activity and gene expression. Functional effects were evaluated by gelatin zymography and cell invasion assays. An orthotopic model of metastatic human EOC in mice was used for in vivo studies.
  
  
  RESULTS
  In EOC cell lines, ET-1 induced Src-dependent EGFR transactivation, causing tyrosine (Y) phosphorylation of β-catenin at the residue Y654, its dissociation from E-cadherin complexes and the accumulation as an active form. This pool of Tyr-β-catenin relocalised to the nucleus promoting its transcriptional activity, and the expression of its target genes, such as MMP-2. At functional level, ET-1 and EGFR circuits enhanced protease activity and cell invasion. All these effects were significantly inhibited by the ET(A)R antagonist, zibotentan, or EGFR inhibitor, gefitinib, and are completely blocked by co-addition of both drugs. In vivo, zibotentan treatment significantly inhibited metastases, associated with reduced expression and activation of MMPs and active β-catenin, especially when combined with gefitinib.
  
  
  CONCLUSIONS
  Altogether these findings provide additional support to the potential use of ET(A)R and EGFR blockade as a new therapeutic opportunity for EOC treatment.
authors.affiliation: Laboratory of Molecular Pathology, Regina Elena Cancer Institute, Rome, Italy.
authors.forename: Roberta
authors.initials: R
authors.lastname: Cianfrocca
authors.forename: Piera
authors.initials: P
authors.lastname: Tocci
authors.forename: Francesca
authors.initials: F
authors.lastname: Spinella
authors.forename: Valeriana
authors.initials: V
authors.lastname: Di Castro
authors.forename: Anna
authors.initials: A
authors.lastname: Bagnato
authors.forename: Laura
authors.initials: L
authors.lastname: Rosanò
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000378:metabolism*; D005260:Female; D000077156:Gefitinib; D006801:Humans; D020782:Matrix Metalloproteinases / Q000378:metabolism; D051379:Mice; D008819:Mice, Nude; D009362:Neoplasm Metastasis; D010051:Ovarian Neoplasms / Q000188:drug therapy / Q000473:pathology*; D010766:Phosphorylation; D011759:Pyrrolidines / Q000008:administration & dosage; D011799:Quinazolines / Q000008:administration & dosage; D044022:Receptor, Endothelin A / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D051176:beta Catenin / Q000378:metabolism*
chemical_list: D011759:Pyrrolidines; D011799:Quinazolines; D044022:Receptor, Endothelin A; C511404:ZD4054; D051176:beta Catenin; D066246:ErbB Receptors; D020782:Matrix Metalloproteinases; D000077156:Gefitinib