VEGF upregulates Bcl-2 expression and is associated with decreased apoptosis in neuroblastoma cells

Background/Purpose: Both the expression of Bcl-2 and the amount of vascular endothelial growth factor (VEGF) are increased in neuroblastoma cells cocultured with hepatocytes. The authors hypothesize that VEGF upregulates Bcl-2 expression by the neuroblastoma cells and protects them from apoptotic stimuli. Methods: To determine whether VEGF will induce Bcl-2 expression in neuroblastoma cells, the cells are plated with standard media (control) or media supplemented with VEGF. After 24 hours, Bcl-2 expression is measured. To determine whether VEGF protects neuroblastoma cells from apoptosis, the cells are subjected to tumor necrosis factor alpha (TNF-[alpha ]) or serum starvation to induce apoptosis either with or without VEGF added to the culture media. The cells are collected and apoptosis measured using the deoxynucleotidyltransferase-mediated dUTP neck end labeling (TUNEL) method. Results: VEGF increases Bcl-2 expression by 33% over cells cultured in standard media. Serum starving the tumor cells or adding TNF-[alpha ] significantly increases the percentage of apoptotic cells. The addition of VEGF significantly protects the neuroblastoma cells from the apoptotic effects of both serum starvation and TNF-[alpha ]. Conclusions: VEGF increases the expression of Bcl-2 and also abrogates TNF-[alpha ] and serum starvation[ndash ]induced apoptosis in neuroblastoma cells in vitro. VEGF may promote neuroblastoma survival not only through angiogenesis, but also by altering apoptosis and its regulating proteins.