title: HER2 carboxyl-terminal fragments regulate cell migration and cortactin phosphorylation.
abstract: A group of breast cancer patients with a higher probability of developing metastasis expresses a series of carboxyl-terminal fragments (CTFs) of the tyrosine kinase receptor HER2. One of these fragments, 611-CTF, is a hyperactive form of HER2 that constitutively establishes homodimers maintained by disulfide bonds, making it an excellent model to study overactivation of HER2 during tumor progression and metastasis. Here we show that expression of 611-CTF increases cell motility in a variety of assays. Since cell motility is frequently regulated by phosphorylation/dephosphorylation, we looked for phosphoproteins mediating the effect of 611-CTF using two alternative proteomic approaches, stable isotope labeling with amino acids in cell culture and difference gel electrophoresis, and found that the latter is particularly well suited to detect changes in multiphosphorylated proteins. The difference gel electrophoresis screening identified cortactin, a cytoskeleton-binding protein involved in the regulation of cell migration, as a phosphoprotein probably regulated by 611-CTF. This result was validated by characterizing cortactin in cells expressing this HER2 fragment. Finally, we showed that the knockdown of cortactin impairs 611-CTF-induced cell migration. These results suggest that cortactin is a target of 611-CTF involved in the regulation of cell migration and, thus, in the metastatic behavior of breast tumors expressing this CTF.
authors: Medical Oncology Research Program, Vall d'Hebron University Hospital, Passeig Vall d'Hebron 119-129, 08035 Barcelona, Spain.
authors: Jesús
authors: J
authors: García-Castillo
authors: Kim
authors: K
authors: Pedersen
authors: Pier-Davide
authors: PD
authors: Angelini
authors: Joan Josep
authors: JJ
authors: Bech-Serra
authors: Núria
authors: N
authors: Colomé
authors: Matthew Paul
authors: MP
authors: Cunningham
authors: Josep Lluis
authors: JL
authors: Parra-Palau
authors: Francesc
authors: F
authors: Canals
authors: José
authors: J
authors: Baselga
authors: Joaquín
authors: J
authors: Arribas
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D051356:Cortactin / Q000737:chemistry*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry; D010750:Phosphoproteins / Q000737:chemistry; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000737:chemistry*; D015398:Signal Transduction
chemical_list: D051356:Cortactin; D010455:Peptides; D010750:Phosphoproteins; D018719:Erb-b2 Receptor Tyrosine Kinases