title: Tumor origin of endothelial cells in human neuroblastoma.
abstract: OBJECTIVE
  Malignant cells are genetically unstable and prone to develop chemotherapy resistance, whereas tumor vasculature is usually of host origin and genetically stable. Tumor endothelial microvessels attract interest as therapeutic targets, but their genetic instability would curtail such approach. Here, we have investigated the tumor origin of endothelial microvessels in human neuroblastoma (NB).
  
  
  METHODS
  Paraffin-embedded tissue sections from 10 MYCN-amplified tumors (six stage 4, three stage 3, and one stage 1) were studied. Endothelial cells (ECs) were detected by immunofluorescent staining for CD31 or CD105, and MYCN amplification was detected using fluorescence in situ hybridization (FISH). In xenografts of the HTLA-230 human NB cell line, human ECs were detected by CD31 staining, mouse ECs were detected by CD34 staining, and MYCN amplification and murine DNA were detected using FISH.
  
  
  RESULTS
  MYCN-amplified ECs formed approximately 70% of tumor endothelial microvessels in two stage 4 tumors and 20% in one stage 3 tumor. Similar results were obtained after EC labeling with CD31 or CD105. Staining for alpha-smooth muscle actin in combination with MYCN FISH demonstrated that tumor-derived ECs were coated with pericytes. These vessels were functional because they contained RBCs. Approximately 70% of endothelial vessels from HTLA-230 xenografts stained for human CD31, but not murine CD34, and displayed MYCN amplification, thus proving their tumor origin.
  
  
  CONCLUSIONS
  NB-associated endothelial microvessels can originate from tumor cells, and this finding challenges the tenet that tumor vasculature is genetically stable. The possibility that NB-derived ECs are chemotherapy resistant warrants further investigation.
authors.affiliation: Laboratories of Oncology and Pathology, G. Gaslini Institute, Genova, Italy. annalisapezzolo@ospedale-gaslini.ge.it
authors.forename: Annalisa
authors.initials: A
authors.lastname: Pezzolo
authors.forename: Federica
authors.initials: F
authors.lastname: Parodi
authors.forename: Maria Valeria
authors.initials: MV
authors.lastname: Corrias
authors.forename: Roberta
authors.initials: R
authors.lastname: Cinti
authors.forename: Claudio
authors.initials: C
authors.lastname: Gambini
authors.forename: Vito
authors.initials: V
authors.lastname: Pistoia
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D019008:Drug Resistance, Neoplasm; D000071063:Endoglin; D042783:Endothelial Cells / Q000145:classification / Q000502:physiology*; D005784:Gene Amplification; D042822:Genomic Instability; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D051379:Mice; D016513:Mice, SCID; D008833:Microcirculation; D000071447:N-Myc Proto-Oncogene Protein; D009389:Neovascularization, Pathologic; D009447:Neuroblastoma / Q000098:blood supply* / Q000235:genetics / Q000473:pathology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D014183:Transplantation, Heterologous
chemical_list: D015703:Antigens, CD; C064206:ENG protein, human; D000071063:Endoglin; C459801:MYCN protein, human; D000071447:N-Myc Proto-Oncogene Protein; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011956:Receptors, Cell Surface