Experimental Study On The Inhibition Of Angiogenesis And Tumor Growth Of Glioma With VEGF Antisense Oligonucleotides

Clinic and experimental studies suggest that angiogenesis is a prerequisite for solid tumor growth. Angiogenesis is a process by which new vascular networks are formed from prexisting capillaries. In the absence of neovascularization most tumors might become dormant at a tiny diameter ,perhaps 2-3mm. At the time of clinic diagnosis solid tumors are already well vascularized and contain vessels at different degrees of maturity.Gliomas ,the most malignant brain tumors, have migrated from the primary site of malignant gliomas by the time of diagnosis in the majority of cases and are responsible for the local recurrence and tumor progression seen clinically.Most available treatment modalities fail to improve survival time and quality of life in patients with gliomas.To improve the prognosis for primary malignant tumors of the central nervous system, we need to expand the focus of our effects. The molecular analysis of growth regulation in gliomas may provide an opportunity for the development of improved therapy. Among targets suitable for new therapies are regulators of angiogenesis. The strategy has 3 advantages (a) it should be applicable to many types of solid tumors because all require a blood supply for survival and growth; (b) the target endothelial cells are directly accessible through the blood and are normal cells, making the outgrowth of resistant mutants unlikely; (c) there is an in-bulit amplification mechanism because thousands of tumor cells are reliant on each capillary for nutrients and oxygen. Studies show VEGF (vascular endothelial growth factor) plays a critical role in tumor angiogenesis. Therefore, Blocking the effects of VEGF may be enough to suppress most angiogenesis, not only directly but also by suppressing 9 its synergistic interaction with other mitogens. So VEGF is a valuable mark of antiangiogenesis. Inhibition of angiogenesis may therefore be an approach to destroying tumors that are highly vascularized and not treatable by conventional methods. These molecules are especially important in gliomas because hypervascularization is a major feature of the tumors. So gliomas are suitable for the treatment of antiangiogenesis . Antisense oligonucleotides(ODNs) offer the potential to block the expression of specific genes within cells. We therefore emploied ODNs complementary to VEGFmRNA to observe their effects on the inhibition of angiogenesis and tumor growth of C6 gliomas in vitro and in vivo. In addition, we also observe the relationship among the VEGF, PCNA and MVD in clinic tumor samples. The study can be divided into three parts briefly described as below: Part 1. In Vitro study Inhibition of VEGF expression of C6 glioma cells and proliferation of endothelial cells with VEGF antisense oligonucleotides(ODNs) To clarify the inhibition of the expression of vascular endothelial growth factor of C6 glioma cells and the proliferation of endothelial cells by Vascular endothelial growth factor (VEGF) antisense oligonucleotides (ODNs). 1. Antisense, sense, and scrambled ODNs targeted to VEGFmRNA were synthesised . To produced the medium conditioned , C6 glioma cells were incubated at a density of 1×104/200ul per well in 96-well plates in media without or with antisense, sense, scrambled ODNs with three concentrations of 5UM, bUM, 2OUM, se...