title: The scaffolding protein NHERF1 sensitizes EGFR-dependent tumor growth, motility and invadopodia function to gefitinib treatment in breast cancer cells.
abstract: Triple negative breast cancer (TNBC) patients cannot be treated with endocrine therapy or targeted therapies due to lack of related receptors. These patients overexpress the epidermal growth factor receptor (EGFR), but are resistant to tyrosine kinase inhibitors (TKIs) and anti-EGFR therapies. Mechanisms suggested for resistance to TKIs include EGFR independence, mutations and alterations in EGFR and in its downstream signalling pathways. Ligand-induced endocytosis and degradation of EGFR play important roles in the downregulation of the EGFR signal suggesting that its activity could be regulated by targeting its trafficking. Evidence in normal cells showing that the scaffolding protein Na+/H+ exchanger regulatory factor 1 (NHERF1) can associate with EGFR to regulate its trafficking, led us to hypothesize that NHERF1 expression levels could regulate EGFR trafficking and functional expression in TNBC cells and, in this way, modulate its role in progression and response to treatment. We investigated the subcellular localization of NHERF1 and its interaction with EGFR in a metastatic basal like TNBC cell model, MDA-MB‑231, and the role of forced NHERF1 overexpression and/or stimulation with EGF on the sensitivity to EGFR specific TKI treatment with gefitinib. Stimulation with EGF induces an interaction of NHERF1 with EGFR to regulate its localization, degradation and function. NHERF1 overexpression is sufficient to drive its interaction with EGFR in non-stimulated conditions, inhibits EGFR degradation and increases its retention time in the plasma membrane. Importantly, NHERF1 overexpression strongly sensitized the cell to the pharmacological inhibition by gefitinib of EGFR-driven growth, motility and invadopodia-dependent ECM proteolysis. The further determination of how the NHERF1‑EGFR interaction is regulated may improve our understanding of TNBC resistance to the action of existing anticancer drugs.
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, I-70125 Bari, Italy.
authors.forename: Antonia
authors.initials: A
authors.lastname: Bellizzi
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, I-70125 Bari, Italy.
authors.forename: Maria Raffaella
authors.initials: MR
authors.lastname: Greco
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, I-70125 Bari, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Rubino
authors.affiliation: Clinical Experimental Oncology Laboratory, National Cancer Research Centre 'Giovanni Paolo II', I-70124 Bari, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Paradiso
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, I-70125 Bari, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Forciniti
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, I-70125 Bari, Italy.
authors.forename: Katrine
authors.initials: K
authors.lastname: Zeeberg
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, I-70125 Bari, Italy.
authors.forename: Rosa Angela
authors.initials: RA
authors.lastname: Cardone
authors.affiliation: Department of Biosciences, Biotechnology and Biopharmaceutics, University of Bari, I-70125 Bari, Italy.
authors.forename: Stephan Joel
authors.initials: SJ
authors.lastname: Reshkin
mesh_terms: D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000502:physiology*; D005260:Female; D000077156:Gefitinib; D006801:Humans; D009361:Neoplasm Invasiveness; D010750:Phosphoproteins / Q000502:physiology*; D051179:Plakins / Q000502:physiology; D021381:Protein Transport / Q000187:drug effects / Q000235:genetics; D011554:Pseudopodia / Q000187:drug effects / Q000235:genetics; D011799:Quinazolines / Q000627:therapeutic use*; D017923:Sodium-Hydrogen Exchangers / Q000502:physiology*; D064726:Triple Negative Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology*; D014407:Tumor Cells, Cultured
chemical_list: D010750:Phosphoproteins; D051179:Plakins; D011799:Quinazolines; D017923:Sodium-Hydrogen Exchangers; C093376:sodium-hydrogen exchanger regulatory factor; C512478:EGFR protein, human; D066246:ErbB Receptors; D000077156:Gefitinib