Vascular endothelial growth factor receptor 2 (VEGFR-2) signalling activity in paediatric pilocytic astrocytoma is restricted to tumour endothelial cells

A H Sikkema, E S J M de Bont, G Molema, A Dimberg, P J Zwiers, S H Diks, Eelco W Hoving, W A Kamps, M P Peppelenbosch, W F A den Dunnen

Research output: Contribution to journalArticleAcademicpeer-review


AIMS: Tumours depend on angiogenesis for enhanced tumour cell survival and progression. Vascular endothelial growth factor receptor (VEGFR) signalling plays a major part in this process. Previously, we evaluated tyrosine kinase activity in paediatric brain tumour tissue lysates using a peptide microarray containing 144 different tyrosine kinase peptide substrates. When applied to paediatric pilocytic astrocytoma tissue, this analysis revealed extensive phosphorylation of VEGFR-derived peptides. The aim of the current study was to validate this result and determine the presence of VEGFR-2 activity in paediatric pilocytic astrocytoma as the main VEGFR in terms of mitogenic signalling. In addition, the localization of VEGFR1-3 mRNA expression was assessed.

METHODS: VEGFR-2 phosphorylation was determined by adopting a proximity ligation assay approach. Enrichment of endothelial markers and VEGFRs in tumour endothelium was determined by quantitative polymerase chain reaction (qPCR) analysis of laser-microdissected blood vessels.

RESULTS: Proximity ligation assays on tumour cryosections showed the presence of phosphorylation of VEGFR-2, which primarily localized to vascular endothelium. qPCR analysis of endothelial markers and VEGFRs showed a 13.6-fold average enrichment of VEGFR-2 expression in the laser-microdissected endothelium compared to whole tumour. Also the expression of VEGFR-1 and -3 was highly enriched in the endothelium fraction with an average fold-enrichment of 16.5 and 50.8 respectively.

CONCLUSIONS: Phosphorylated VEGFR-2 is detected on endothelial cells in paediatric pilocytic astrocytoma. Furthermore, endothelial cells are the main source of VEGFR1-3 mRNA expression. This suggests a crucial role for VEGF/VEGFR-induced angiogenesis in the progression and maintenance of these tumours.

Original languageEnglish
Pages (from-to)538-48
Number of pages11
JournalNeuropathology and Applied Neurobiology
Issue number5
Publication statusPublished - Aug 2011


  • Astrocytoma/metabolism
  • Child
  • Endothelial Cells/metabolism
  • Fluorescent Antibody Technique
  • Humans
  • Lasers
  • Microdissection
  • Neovascularization, Pathologic/metabolism
  • Phosphorylation
  • Protein Array Analysis
  • RNA, Messenger/analysis
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction/physiology
  • Vascular Endothelial Growth Factor Receptor-1/analysis
  • Vascular Endothelial Growth Factor Receptor-2/analysis
  • Vascular Endothelial Growth Factor Receptor-3/analysis


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