Expression Of Vascular Endothelial Growth Factor Receptors In Human Astrocytic Tumor

0bjectives: we recently detected the expression of vascu1arendothelial growth factor (VEGF) in human gliomas. VEGF exerts itsangiogenic and pro-tumorigenic properties by way of two high affinityreceptors, fms-like tyrosine kinase 1 (flt-1) and fetal liver kinase1(flk-1), which are expressed mainly in vascu1ar endothelial cells. Wehypothesized that these receptors are expressed and controlled VEGFfunctions in the astrocytic tumor microenvironment. Herein, we evaluatethe expression of these receptors in 1-2 grade astrocytic tumor tissue,3 grade astrocytic tumor tissue and glioblastome tissue.Methods: The 51 astrocytic tumor specimens were obtained frompatients undergoing tumorectomy. 6 injured brain tissue specimens wereused as the contrast. Inununohistochemical analysi susing antihuman flt-1and flk-1 was performed and specimens were analyzed to characterize theexpression and distribution of both receptors.ResU1ts: (1). There is no flt-1 and flk-1 expression in the normalbrain tissue. (2). VEGFR main1y expressed in the vascular endothe1ia1cel1s. In some tumor specimens, the macrophages were also detectedpositive expression of flt-1. (3) The expression rate of VEGFR in 1-2 gradeastrocyt ic tumors, 3 grade astrocytic tumors and glioblastoma are 16. 7%,52. 9% and 90% correspondingly. The expression of VEGFR in 3 and 4 gradetumors is significantly more than that in lower grade tumors (P<0. 01).(3). The expression of flt-1 is correlated to that of flk-1 (P<0. 01).Conclusion: Both flt-1 and flk-1 are presented in astrocytictumor and correlated to the tumor grade. Expression of VEGFR on vascu1arendothelial cells of tumor vessel supports the well-established role ofVEGF in paracrine stimu1ation of vascu1ar endothelial cells in the tumormicroenvironment. VEGF also exertsits angiogenic effect through theinfiltration of macrophage.