F. Agani et al., P53 DOES NOT REPRESS HYPOXIA-INDUCED TRANSCRIPTION OF THE VASCULAR ENDOTHELIAL GROWTH-FACTOR GENE, Cancer research, 57(20), 1997, pp. 4474-4477
Hypoxia-induced neovascularization mediated by vascular endothelial gr
owth factor (VEGF) contributes to tumor progression, Based on its effe
cts when overexpressed in transient transfection assays, p53 has been
proposed to repress VEGF transcription, To investigate this hypothesis
, we have analyzed endogenous VEGF mRNA levels in Hep3B cells stably e
xpressing an inducible p53-estrogen receptor fusion protein and in irr
adiated RKO cells expressing endogenous wild-type p53, In both cell li
nes, VEGF mRNA levels increased in response to hypoxia, either in the
presence or absence of functional p53. Our data provide no evidence fo
r a causal relationship between the loss of p53 activity and increased
VEGF expression that is observed during tumor progression, Studies th
at attribute repressor functions to p53 based on analysis of cells tra
nsiently overexpressing this protein should be interpreted cautiously.