Upregulation of vascular endothelial growth factor receptors is associated with advanced neuroblastoma.
BACKGROUND
Angiogenesis is essential for tumor growth and relies on the production of angiogenic factors. Vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis that binds to tyrosine kinase receptors Flt-1 and KDR. The interaction of VEGF and its receptors at gene and protein levels in neuroblastoma remains widely unknown.


METHODS
Tumor biopsy specimens and serum were obtained from 37 neuroblastoma patients; adrenal biopsy sections and sera of 7 normal children served as controls. Biopsy specimens were examined by real-time reverse transcription polymerase chain reaction (RT-PCR) and Western blotting; serum was analyzed by enzyme-linked immunosorbent assay (ELISA). VEGF-A(165), B, C, Flt-1, and KDR were analyzed.


RESULTS
VEGF isoforms and its receptors' mRNA were expressed in neuroblastoma and control tissues. Whereas the ligands were increased in stages III and IV, the receptors were upregulated in stage III only. At protein level, VEGF-B and C, Flt-1, and KDR were not detectable in tissue lysates, whereas VEGF-A was increased in stages III and IV. Serum VEGF protein levels were upregulated in stage III.


CONCLUSIONS
VEGF-A(165) is one of the major angiogenesis regulators among the ligands' family of VEGF, whereas its receptors KDR, and most probably Flt-1, may contribute to a poor prognosis (angiogenic) phenotype, as indicated by their upregulated MRNA levels in stage III neuroblastoma. VEGF-A(165) mainly contributes to increased serum VEGF levels and may serve as a diagnostic tool in advanced-stage neuroblastoma.
Fakhari
M
M
Laboratory for Cardiovascular Research, Departments of Anatomy, Pediatric Surgery, and Molecular Biology, University of Vienna, Vienna, Austria.
Pullirsch
D
D
Paya
K
K
Abraham
D
D
Hofbauer
R
R
Aharinejad
S
S
D000310:Adrenal Gland Neoplasms / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D001706:Biopsy; D015153:Blotting, Western; D016228:Endothelial Growth Factors / Q000097:blood / Q000235:genetics / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007223:Infant; D008222:Lymphokines / Q000097:blood / Q000235:genetics / Q000378:metabolism; D008297:Male; D009447:Neuroblastoma / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D020794:Receptor Protein-Tyrosine Kinases / Q000097:blood / Q000378:metabolism*; D017978:Receptors, Growth Factor / Q000097:blood / Q000378:metabolism*; D040262:Receptors, Vascular Endothelial Growth Factor; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D017978:Receptors, Growth Factor; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D020794:Receptor Protein-Tyrosine Kinases; D040262:Receptors, Vascular Endothelial Growth Factor