title: Targeting CXCR4 by a selective peptide antagonist modulates tumor microenvironment and microglia reactivity in a human glioblastoma model.
abstract: BACKGROUND
  The CXCL12/CXCR4 pathway regulates tumor cell proliferation, metastasis, angiogenesis and the tumor-microenvironment cross-talk in several solid tumors, including glioblastoma (GBM), the most common and fatal brain cancer. In the present study, we evaluated the effects of peptide R, a new specific CXCR4 antagonist that we recently developed by a ligand-based approach, in an in vitro and in vivo model of GBM. The well-characterized CXCR4 antagonist Plerixafor was also included in the study.
  
  
  METHODS
  The effects of peptide R on CXCR4 expression, cell survival and migration were assessed on the human glioblastoma cell line U87MG exposed to CXCL12, by immunofluorescence and western blotting, MTT assay, flow cytometry and transwell chamber migration assay. Peptide R was then tested in vivo, by using U87MG intracranial xenografts in CD1 nude mice. Peptide R was administered for 23 days since cell implantation and tumor volume was assessed by magnetic resonance imaging (MRI) at 4.7 T. Glioma associated microglia/macrophage (GAMs) polarization (anti-tumor M1 versus pro-tumor M2 phenotypes) and expressions of vascular endothelial growth factor (VEGF) and CD31 were assessed by immunohistochemistry and immunofluorescence.
  
  
  RESULTS
  We found that peptide R impairs the metabolic activity and cell proliferation of human U87MG cells and stably reduces CXCR4 expression and cell migration in response to CXCL12 in vitro. In the orthotopic U87MG model, peptide R reduced tumor cellularity, promoted M1 features of GAMs and astrogliosis, and hindered intra-tumor vasculature.
  
  
  CONCLUSIONS
  Our findings suggest that targeting CXCR4 by peptide R might represent a novel therapeutic approach against GBM, and contribute to the rationale to further explore in more complex pre-clinical settings the therapeutic potential of peptide R, alone or in combination with standard therapies of GBM.
authors.affiliation: Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Mercurio
authors.affiliation: Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Ajmone-Cat
authors.affiliation: Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Serena
authors.initials: S
authors.lastname: Cecchetti
authors.affiliation: Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ricci
authors.affiliation: Department of Technology and Health, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Bozzuto
authors.affiliation: Department of Technology and Health, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Agnese
authors.initials: A
authors.lastname: Molinari
authors.affiliation: Department of Research, Diagnosis and Innovative Technologies, Regina Elena National Cancer Institute, Rome, Italy.
authors.forename: Isabella
authors.initials: I
authors.lastname: Manni
authors.affiliation: Division of Neuropathology, Fondazione IRCCS Istituto Neurologico C. Besta, Milan, Italy.
authors.forename: Bianca
authors.initials: B
authors.lastname: Pollo
authors.affiliation: Molecular Immunology, Functional Genomics, Istituto Nazionale per lo Studio e la Cura dei Tumori, "Fondazione G. Pascale" IRCCS, Napoli, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Scala
authors.affiliation: Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy. giulia.carpinelli@iss.it.
authors.forename: Giulia
authors.initials: G
authors.lastname: Carpinelli
authors.affiliation: Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Rome, Italy. luisa.minghetti@iss.it.
authors.forename: Luisa
authors.initials: L
authors.lastname: Minghetti
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D054377:Chemokine CXCL12 / Q000037:antagonists & inhibitors*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D017628:Microglia / Q000187:drug effects* / Q000473:pathology; D010455:Peptides / Q000008:administration & dosage* / Q000494:pharmacology; D019718:Receptors, CXCR4 / Q000037:antagonists & inhibitors*; D047368:Tumor Burden / Q000187:drug effects; D059016:Tumor Microenvironment / Q000187:drug effects; D023041:Xenograft Model Antitumor Assays
chemical_list: C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D010455:Peptides; D019718:Receptors, CXCR4
keywords: CXCL12; CXCR4; GAM; Glioma; Macrophage polarization; Microglia; Plerixafor; Tumor microenvironment