VEGF-mediated survivin expression in neuroblastoma cells.
BACKGROUND
Vascular endothelial growth factor (VEGF) up-regulates a number of cellular survival signals in endothelial cells. We hypothesize that VEGF will up-regulate survivin, a member of the IAP family of anti-apoptotic proteins, via the PI3K/Akt cell signaling pathway in human neuroblastoma cells.


METHODS
IMR-32 human neuroblastoma cells are cultured with VEGF at varying times and in escalating doses. A specific inhibitor of PI3-kinase, LY294002, is used to block Akt phosphorylation. Immunoblot is used to measure protein expression, and Hoechst staining is used to detect apoptosis.


RESULTS
Stimulation of IMR-32 neuroblastoma cells with VEGF results in an increase in survivin protein expression in both a dose- and a time-dependent fashion. Akt phosphorylation is also increased after stimulation with exogenous VEGF. Blockade of Akt phosphorylation with LY294002 abrogates the effects of VEGF upon survivin and phosphorylated Akt protein expression.


CONCLUSIONS
VEGF has been shown to up-regulate a number of survival signals in endothelial cells. We have found that exposure of human neuroblastoma cells to exogenous VEGF results in an increased expression of survivin protein and phosphorylated Akt, and inhibition of PI3-kinase abrogates those effects. It appears that VEGF is important for promotion of neuroblastoma cellular survival through the up-regulation of survival proteins, and not only through its angiogenic properties.
Beierle
Elizabeth A
EA
Department of Surgery, University of Florida, Gainesville, Florida 32610-0286, USA. beierea@surgery.ufl.edu
Nagaram
Abhilasha
A
Dai
Wei
W
Iyengar
Meera
M
Chen
Mike K
MK
D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins / Q000235:genetics*; D009025:Morpholines / Q000494:pharmacology; D009363:Neoplasm Proteins; D009447:Neuroblastoma; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors; D051057:Proto-Oncogene Proteins c-akt; D019311:Staurosporine / Q000494:pharmacology; D000077022:Survivin; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
C107489:BIRC5 protein, human; D002867:Chromones; D004791:Enzyme Inhibitors; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009025:Morpholines; D009363:Neoplasm Proteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D000077022:Survivin; D042461:Vascular Endothelial Growth Factor A; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019311:Staurosporine