title: Targeting of BRAF resistant melanoma via extracellular matrix metalloproteinase inducer receptor.
abstract: BACKGROUND
  The BRAF inhibitor vemurafenib (PLX) has shown promise in treating metastatic melanoma, but most patients develop resistance to treatment after 6 mo. We identified a transmembrane protein, extracellular matrix metalloproteinase inducer (EMMPRIN) as a cell surface receptor highly expressed by PLX-resistant melanoma. Using an S100A9 ligand, we created an EMMPRIN targeted probe and liposome that binds to melanoma cells in vivo, thus designing a novel drug delivery vehicle.
  
  
  METHODS
  PLX-resistant cells were established through continuous treatment with PLX-4032 over the course of 1 y. Both PLX-resistant and sensitive melanoma cell lines were evaluated for the expression of unique cell surface proteins, which identified EMMPRIN as an overexpressed protein in PLX0-resistant cells and S100A9 is a ligand for EMMPRIN. To design a probe for EMMPRIN, S100A9 ligand was conjugated to a CF-750 near-infrared (NIR) dye. EMMPRIN targeted liposomes were created to encapsulate CF-750 NIR dye. Liposomes were characterized by scanning electron microscopy, flow cytometry, and in vivo analysis. A2058PLX and A2058 cells were subcutaneously injected into athymic mice. S100A9 liposomes were intravenously injected and tumor accumulation was evaluated using NIR fluorescent imaging.
  
  
  RESULTS
  Western blot and flow cytometry demonstrated that PLX sensitive and resistant A2058 and A375 melanoma cells highly express EMMPRIN. S100A9 liposomes were 200 nm diameter and uniformly sized. Flow cytometry demonstrated 100X more intracellular dye uptake by A2058 cells treated with S100A9 liposomes compared with untargeted liposomes. In vivo accumulation of S100A9 liposomes within subcutaneous A2058 and A2058PLX tumors was observed from 6-48 h, with A2058PLX accumulating significantly higher levels (P = 0.001626).
  
  
  CONCLUSIONS
  EMMPRIN-targeted liposomes via an S100A9 ligand are a novel, targeted delivery system which could provide improved EMMPRIN specific drug delivery to a tumor.
authors.affiliation: Hiram C. Polk Jr. MD Department of Surgery, University of Louisville, Louisville, Kentucky.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Zeiderman
authors.affiliation: Hiram C. Polk Jr. MD Department of Surgery, University of Louisville, Louisville, Kentucky.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Egger
authors.affiliation: Hiram C. Polk Jr. MD Department of Surgery, University of Louisville, Louisville, Kentucky.
authors.forename: Charles W
authors.initials: CW
authors.lastname: Kimbrough
authors.affiliation: Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: England
authors.affiliation: Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky.
authors.forename: Tess V
authors.initials: TV
authors.lastname: Dupre
authors.affiliation: Hiram C. Polk Jr. MD Department of Surgery, University of Louisville, Louisville, Kentucky.
authors.forename: Kelly M
authors.initials: KM
authors.lastname: McMasters
authors.affiliation: Department of Medicine, University of Louisville, Louisville, Kentucky. Electronic address: lrmcna01@louisville.edu.
authors.forename: Lacey R
authors.initials: LR
authors.lastname: McNally
mesh_terms: D000818:Animals; D051926:Basigin / Q000502:physiology*; D040502:Calgranulin B / Q000008:administration & dosage / Q000378:metabolism; D045744:Cell Line, Tumor; D016503:Drug Delivery Systems; D019008:Drug Resistance, Neoplasm; D005260:Female; D006801:Humans; D007211:Indoles / Q000627:therapeutic use*; D008081:Liposomes; D008545:Melanoma / Q000188:drug therapy*; D051379:Mice; D048493:Proto-Oncogene Proteins B-raf / Q000037:antagonists & inhibitors*; D013449:Sulfonamides / Q000627:therapeutic use*; D000077484:Vemurafenib
chemical_list: C497886:BSG protein, human; D040502:Calgranulin B; D007211:Indoles; D008081:Liposomes; D013449:Sulfonamides; D051926:Basigin; D000077484:Vemurafenib; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF; EMMPRIN; Imaging; Liposome; Melanoma; Nanoparticles; Near-infrared; Resistant; S100A9; Targeted drug delivery