Neurofibromas of neurofibromatosis 1 (NF1) are highly vascular. Because the number of PDGF beta receptors in neurofibroma-derived cultured cells (NF-derived cells) has been reported to be increased, we tested whether platelet-derived growth factor BB (PDGF-BB) could induce expression of vascular endothelial growth factor (VEGF) in NF-derived cells. When analysed by reverse transcription-polymerase chain reaction, VEGF mRNA expression was found to be stimulated by PDGF-BB and TGF-beta1. Those growth factors stimulated the secretion of VEGF from NF-derived cells. PDGF-BB furthermore induced the mitogen-activated protein kinase phosphorylation in NF-derived cells from patients with NF1. In conclusion, PDGF-BB stimulated VEGF secretion in NF-derived cells, and this stimulation is probably important in neurofibroma hypervascularization.

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