Expression of vascular endothelial growth factor-b in human astrocytoma

Growth of human malignant gliomas is stringently dependent on an angiogenic process that probably involves vascular endothelial growth factor (VEGF), Expressions of mRNA coding for the different forms of VEGF were analyzed in surgical specimens from human astrocytomas, Low levels of placental growth factor (PGF) and VEGFC mRNA were observed in polymerase chain reaction, bu t not in Northern blot experiments. VEGF mRNA was found in some but not all grade and grade TV astrocytomas. VEGFB mRNA was observed in all tissue sam ples anal)zed irrespective of the tumor grade. A new splice variant of VEGF B (VEGFB(155)) that lacks exons 5 and 6 is described. Expressions of VEGF m RNA in cultured glioblastomas cells were upregulated by hypoxia, but the se nsitivity of the cells to hypoxia was reduced as compared with normal rat a strocytes, VEGF expression was depressed by dexamethasone, Expressions of V EGFB mRNA were affected neither by hypoxia nor by dexamethasone, The result s indicate a coexpression of VEGF mRNA and VEGFB mRNA in human astrocytomas , Expression of VEGFB is markedly different from that of VEGF. Possible rol es of VEGFB as a cofactor for hypoxia-induced angiogenesis in human astrocy tomas are discussed.