title: Implications of Dll4-Notch signaling activation in primary glioblastoma multiforme.
abstract: BACKGROUND
  Glioblastoma multiforme (GBM) is a highly aggressive brain tumor characterized by massive neovascularization, necrosis, and intense resistance to therapy. Deregulated Notch signaling has been implicated in the formation and progression of different malignancies. The present study attempted to investigate the activation status of Dll4-Notch signaling in primary human GBM and its association with vascular and clinical parameters in patients.
  
  
  METHODS
  Major components of Dll4-Notch signaling were examined by real-time reverse-transcription polymerase chain reaction (PCR), Western blotting, and immunohistochemistry in GBM (n = 26) and control (n = 11) brain tissue. The vascular pattern (VP) and microvascular density (MVD) were analyzed after laminin immunostaining. O6-Methylguanine-methyltransferase (MGMT) promoter methylation in GBM samples was detected by methylation-specific PCR.
  
  
  RESULTS
  The mRNA levels of Dll4, Jagged1, Notch1, Notch4, Hey1, Hey2, Hes1, and VEGF were 3.12-, 3.58-, 3.37-, 5.77-, 4.89-, 3.13-, 6.62-, and 32.57-fold elevated, respectively, in GBM samples, compared with the controls. Western blotting revealed a 4-, 3.7-, and 45.6-fold upregulation of Dll4, Notch1, and Hey1, respectively, accompanied by a downregulation of PTEN expression and an increase in the expression of p-Akt and VEGF. Immunostaining located the immunoreactivity of Dll4 and Notch1 in endothelial cells, microglia/macrophages, tumor cells, and astrocytes. Furthermore, the upregulation of Dll4-Notch signaling components was correlated to a low MVD and was potentially related to a classic VP, tumor edema, and MGMT promoter methylation.
  
  
  CONCLUSIONS
  The upregulation of Dll4-Notch signaling components was found in a subset of GBM samples and was associated with some angiogenic and clinical parameters. These findings highlight this signaling pathway as a potential therapeutic target for patients with GBM who show an activation of Dll4-Notch signaling.
authors.affiliation: Corresponding Author: Dr. Yuan Zhu, PhD, Department of Neurosurgery, University of Duisburg-Essen, Hufelandstraße 55, 45122 Essen, Germany. yuan.zhu@uk-essen.de.
authors.forename: Nicolai
authors.initials: N
authors.lastname: El Hindy
authors.forename: Kathy
authors.initials: K
authors.lastname: Keyvani
authors.forename: Axel
authors.initials: A
authors.lastname: Pagenstecher
authors.forename: Philip
authors.initials: P
authors.lastname: Dammann
authors.forename: I Erol
authors.initials: IE
authors.lastname: Sandalcioglu
authors.forename: Ulrich
authors.initials: U
authors.lastname: Sure
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhu
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000368:Aged; D017209:Apoptosis; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002135:Calcium-Binding Proteins; D016022:Case-Control Studies; D049109:Cell Proliferation; D019175:DNA Methylation; D015254:DNA Modification Methylases / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics; D005260:Female; D005455:Fluorescent Antibody Technique; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D051881:Receptor, Notch1 / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002135:Calcium-Binding Proteins; C424126:DLL4 protein, human; D036341:Intercellular Signaling Peptides and Proteins; C497761:NOTCH1 protein, human; D012333:RNA, Messenger; D051881:Receptor, Notch1; D025521:Tumor Suppressor Proteins; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes
keywords: Dll4-Notch signaling; macrophage/microglia; microvascular density; primary glioblastoma multiforme; vascular pattern