Expression of Vascular Endothelial Growth Factor and Its Relation with Neovascularization and Apoptosis in Grading of Astrocytic Tumors

ABSTRACT

BACKGROUND: The vascular endothelial growth factor (VEGF) is known as a potent mediator of brain tumor angio-genesis, vascular permeablity, and glioma growth. This study was designed to study the balance between growth and death signals in different grades of astrocytic tumors. METHODS: Using immunohistochemistry, the relationship between the expression of VEGF and microvessel count and density were evaluated in 62 cases of astrocytic tumors including 33 low grade astrocytomas, 6 anaplastic astrocytomas, and 23 glioblastomas. In order to determine the apoptotic index (AI), the in situ end-labeling method was applied. RESULTS: VEGF was expressed on the tumor cell cytoplasm. Of 62 tumors, 44 (77%) were weak to strong postive for VEGF, but 18 cases were not reactive. VEGF positivity was correlat-ed with WHO grades of the astrocytic tumors; low grade astrocytomas (52%), anaplastic astrocytomas (83%), and glioblastomas (96%). Mean microvessel count and density were significantly higher in VEGF-positive tumors (75.7 and 4.1%) than in VEGF-negative tumors (43.9 and 2.5%). Apoptotic cells were readily found in the astrocytic tumors; the highest value of AI was observed in glioblastomas (8.6%) and the lowest in anaplastic astrocytomas (1.9%). It seemed that the grade of malignancy was not related with AI values. CONCLUSIONS: These results suggest that VEGF promotes angiogenesis with tumor cell growth against apoptotic cell death in the human astrocytomas.