Effect of VEGF over-expressed C6 glioma cells on the expression of Flk-1and Flt-1in cocultured microvascular endothelial cells

AIM: To study the effects of VEGF over-expressed C6 glioma cells on the expression of Flk-1and Flt-1in cocultured microvascular endothelial cells using the rat hepatic cells BRL 3A as control. METHODS: Cocultured systems of rat pulmonary microvascular endothelial cells with C6 and endothelial cells with BRL 3A were established. Immunocytochemical method was used to investigate the expression change of Flk-1and Flt-1protein in cocultured microvascular endothelial cells. The expression of Flt-1and Flk-1mRNA was analyzed by RT-PCR and Northern blot. RESULTS: The microvascular endothelial cells cocultured with C6 showed increased expression of Flk-1and Flt-1protein (P <0.05), while that cocultured with BRL 3A, showed decreased expression of Flt-1and Flk-1protein(P <0.01). The results of RT-PCR and Northern blot showed that the Flk-1, Flt-1mRNA of microvascular endothelial cells were markedly up-regulated after coculture with C6 glioma cells (P <0.01), while the endothelial cells cocultured with BRL 3A had down-regulated expression of Flk-1, Flt-1mRNA (P <0.01). CONCLUSION: VEGF over-expressed C6 glioma cells may markedly up-regulate the expression of Flt-1and Flk-1in cocultured microvascular endothelial cells. These results suggest that this effect could be one of the important mechanisms in glioma angiogenesis in vivo.