Effect Of Vascular Endothelial Growth Factor On Microecosystem Morphology And Aquaporin-4 Expression In Glioma

Objective To investigate the influence of vascular endothelial growth factor (VEGF)on neuro-glioma microecosystem morphology and the expression of aquaporin-4 inglioma cells and tumor parenchyma.Methods (1) The recombinants of VEGF₁₆₄ gene (sense and anti-sense) and eukaryticvector pBudCE4.1 were transfected into C₆ cells by lipofectintechniques. And afterzeocin resistance test, the contents of VEGF which secreted by the positive cloneswere detected by ELISA assay. (2) Glioma models were constructed in nude miceright axillary region by subcutaneously injection of C₆ glioma cells which have beenscreened out through zeocin resistance test and could stably express sense oranti-sense VEGF cDNA. Tumor volume were measured and recorded once two days.The nude mice were sacrificed 21 days after and the volume and weight of the tumorswere measured. (3) The morphologies of the implanted tumors and peritumor tissueswere observed under light and electron microscope. (4) The expression of VEGF andaquaporin-4 in various implanted tumors were detected by immunohistochemicalmethod.Results (1) The contents of VEGF increased in C₆ cells that could stably expresssense VEGF cDNA and decreased in C₆ cells which express anti-sense VEGF cDNA.(2) The growth speed, tumor volume and weight of C₆ gliomas transfected withanti-sense VEGF gene remarkably decreased, C₆ gliomas transfected with senseVEGF gene had no remarkable distinction from normal control. (3) C₆ gliomastransfected with anti-sense VEGF gene have lower capillary supply, mild bleeding,necrosis, peritumor vascular reaction, edema and surrounding invasion, as comparedto sense VEGF gene transfection, empty vector transfection and normal control.Furthermore, there were less vesicular vacuolar organelles in the endothelial cells ofthe C6 gliomas transfected with anti-sense VEGF gene. (4) Transfection withanti-sense VEGF gene remarkably decreased the the expression of VEGF andaquaporin-4 in C6 gliomas as compared with sense VEGF gene, empty vector, andnormal control.Conclusions (1) Anti-sense VEGF gene could efficiently down-regulate theexpression of VEGF in C6 glioma cells. And the pBudCE4.1 had no effects on theexpression of VEGF as a transfect vector. (2) VEGF is an important factor of gliomagrowth, and glioma may grow slower after the down-regulation of the expression ofVEGF in C6 glioma cells. (3) VEGF plays an important role in neuro-gliomamicroecosystem succession, promotes angiogenesis, bleeding, necrosis and migrationof glioma cells and endothelial cells in glioma. Furthermore, it increases the vesicularvacuolar organelles in the endothelial cells and the capillary permeability, andconsequently, change the bionomics of glioma such as edema and invasion. (4) VEGFparticipates in the pathophysiological processes of glioma peritumor edema and tumoredema not only by directly increases the permeability of blood capillary but alsopossibly by regulates the expression of aquaporin-4 in C6 glioma cells.