Flavopiridol inhibits vascular endothelial growth factor production induced by hypoxia or picolinic acid in human neuroblastoma.
Human neuroblastoma (NB) tumors elaborate angiogenic peptides, and enhanced angiogenesis correlates with their aggressive behavior, metastatic spread and poor clinical outcome. Hence, inhibition of angiogenic factor production may represent a potential therapeutic target for NB treatment. There is currently little information regarding the stimuli that control NB production of angiogenic mediators. In this study, we analyzed the effects of hypoxia, a common feature of solid tumors and a major drive to tumor angiogenesis, and of PA, a tryptophan catabolite produced under inflammatory conditions and endowed with several biologic properties, on the production of the angiogenic activator VEGF by advanced-stage human NB cell lines. We demonstrate that both stimuli are potent inducers of VEGF expression and secretion. VEGF upregulation by PA involved iron chelation because iron sulfate prevented this effect whereas the iron-chelating agent DFX induced VEGF production. Conversely, the CDK inhibitor Flp completely blocked VEGF induction by hypoxia. This effect occurred as early as 3 hr after stimulation and did not require de novo protein synthesis. Moreover, Flp exerted similar inhibitory activity on VEGF induction by PA or DFX, suggesting that this compound targets an essential step in the signaling pathway that leads to VEGF expression. Our findings demonstrate that PA can modulate angiogenic factor production by tumor cells and establish the importance of Flp as an inhibitor of VEGF production by human NB.
Rapella
Annamaria
A
Laboratory of Molecular Biology, G. Gaslini Institute, Genoa, Italy.
Negrioli
Anna
A
Melillo
Giovanni
G
Pastorino
Sandra
S
Varesio
Luigi
L
Bosco
Maria Carla
MC
D000970:Antineoplastic Agents / Q000494:pharmacology*; D015687:Cell Hypoxia; D003676:Deferoxamine / Q000494:pharmacology; D016228:Endothelial Growth Factors / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D005296:Ferrous Compounds / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007502:Iron Chelating Agents / Q000494:pharmacology; D008222:Lymphokines / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics; D009447:Neuroblastoma / Q000378:metabolism*; D010848:Picolinic Acids / Q000494:pharmacology*; D010880:Piperidines / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D000970:Antineoplastic Agents; D016228:Endothelial Growth Factors; D005296:Ferrous Compounds; D005419:Flavonoids; D007502:Iron Chelating Agents; D008222:Lymphokines; D010848:Picolinic Acids; D010880:Piperidines; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C020748:ferrous sulfate; C077990:alvocidib; D003676:Deferoxamine; C030614:picolinic acid