title: Ligand-independent EPHA2 signaling drives the adoption of a targeted therapy-mediated metastatic melanoma phenotype.
abstract: Many patients with BRAF inhibitor resistance can develop disease at new sites, suggesting that drug-induced selection pressure drives metastasis. Here, we used mass spectrometry-based phosphoproteomic screening to uncover ligand-independent EPHA2 signaling as an adaptation to BRAF inhibitor therapy that led to the adoption of a metastatic phenotype. The EPHA2-mediated invasion was AKT-dependent and readily reversible upon removal of the drug as well as through PI3K and AKT inhibition. In xenograft models, BRAF inhibition led to the development of EPHA2-positive metastases. A retrospective analysis of patients with melanoma on BRAF inhibitor therapy showed that 68% of those failing therapy develop metastases at new disease sites, compared with 35% of patients on dacarbazine. Further IHC staining of melanoma specimens taken from patients on BRAF inhibitor therapy as well as metastatic samples taken from patients failing therapy showed increased EPHA2 staining. We suggest that inhibition of ligand-independent EPHA2 signaling may limit metastases associated with BRAF inhibitor therapy.
  
  
  CONCLUSIONS
  This study provides evidence that BRAF inhibition promotes the adoption of a reversible, therapy-driven metastatic phenotype in melanoma. The cotargeting of ligand-independent EPHA2 signaling and BRAF may be one strategy to prevent the development of therapy-mediated disease at new sites.
authors.affiliation: Department of Molecular Oncology, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: Kim H T
authors.initials: KH
authors.lastname: Paraiso
authors.affiliation: Novartis Institute for Biomedical Research, Emeryville, California.
authors.forename: Meghna
authors.initials: M
authors.lastname: Das Thakur
authors.affiliation: The Proteomics Core, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: Bin
authors.initials: B
authors.lastname: Fang
authors.affiliation: Department of Molecular Oncology, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: John M
authors.initials: JM
authors.lastname: Koomen
authors.affiliation: Department of Tumor Biology, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: Inna V
authors.initials: IV
authors.lastname: Fedorenko
authors.affiliation: Department of Molecular Oncology, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: Jobin K
authors.initials: JK
authors.lastname: John
authors.affiliation: Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Hensin
authors.initials: H
authors.lastname: Tsao
authors.affiliation: Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Keith T
authors.initials: KT
authors.lastname: Flaherty
authors.affiliation: Department of Cutaneous Oncology, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: Vernon K
authors.initials: VK
authors.lastname: Sondak
authors.affiliation: Department of Cutaneous Oncology, Moffitt Cancer Center and Research Institute, Tampa, Florida. Department of Anatomic Pathology, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: Jane L
authors.initials: JL
authors.lastname: Messina
authors.affiliation: Sanford-Burnham Medical Research Institute, La Jolla, California.
authors.forename: Elena B
authors.initials: EB
authors.lastname: Pasquale
authors.affiliation: Department of Immunology, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Villagra
authors.affiliation: Department of Medicine, Division of Hematology/Oncology, School of Medicine, University of Pittsburgh, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
authors.forename: Uma N
authors.initials: UN
authors.lastname: Rao
authors.affiliation: Department of Medicine, Division of Hematology/Oncology, School of Medicine, University of Pittsburgh, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
authors.forename: John M
authors.initials: JM
authors.lastname: Kirkwood
authors.affiliation: Department of Dermato-Oncology, University of Tuebingen, Tuebingen, Germany.
authors.forename: Friedegund
authors.initials: F
authors.lastname: Meier
authors.affiliation: Department of Cutaneous Oncology, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: Sarah
authors.initials: S
authors.lastname: Sloot
authors.affiliation: Department of Cutaneous Oncology, Moffitt Cancer Center and Research Institute, Tampa, Florida.
authors.forename: Geoffrey T
authors.initials: GT
authors.lastname: Gibney
authors.affiliation: Novartis Institute for Biomedical Research, Emeryville, California.
authors.forename: Darrin
authors.initials: D
authors.lastname: Stuart
authors.affiliation: Department of Medicine, Division of Hematology/Oncology, School of Medicine, University of Pittsburgh, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania.
authors.forename: Hussein
authors.initials: H
authors.lastname: Tawbi
authors.affiliation: Department of Tumor Biology, Moffitt Cancer Center and Research Institute, Tampa, Florida. Department of Cutaneous Oncology, Moffitt Cancer Center and Research Institute, Tampa, Florida. keiran.smalley@moffitt.org.
authors.forename: Keiran S M
authors.initials: KS
authors.lastname: Smalley
mesh_terms: D019008:Drug Resistance, Neoplasm; D006801:Humans; D008024:Ligands; D008545:Melanoma / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology*; D058990:Molecular Targeted Therapy; D009362:Neoplasm Metastasis; D010641:Phenotype; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D025941:Protein Interaction Mapping; D060066:Protein Interaction Maps; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D020543:Proteome; D040901:Proteomics / Q000379:methods; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D036104:Receptor, EphA2 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D008024:Ligands; D010750:Phosphoproteins; D047428:Protein Kinase Inhibitors; D020543:Proteome; D019869:Phosphatidylinositol 3-Kinases; D036104:Receptor, EphA2; D048493:Proto-Oncogene Proteins B-raf; D051057:Proto-Oncogene Proteins c-akt