THE PROLIFERATIVE ACTIVITY (KI-67) AND THE LEVEL OF VASCULAR ENDOTHELIAL GROWTH FACTOR (VEGF) GENE EXPRESSION IN GEMISTOCYTIC ASTROCYTOMAS

Background. Gemistocytic astrocytomas (GA) are a variant of diffuse astrocytomas GII (WHO, 2016), which is characterized by a shorter overall survival of patients than diffuse astrocytoma. The role of vascular endothelial growth factor (VEGF) gene expression and its association with the index of proliferative activity (Ki-67) in GA has not been studied

Objective. To estimate the correlation of VEGF gene expression on Ki-67 in GA.

Design and methods. A retrospective and prospective analysis of morphological and molecular-genetic features of tumors was performed on 9 patients with the diagnosis of GA. Patients over 18 years of age with supratentorial tumor localization were included in the study. The patients were aged from 27 to 37 years, the median age was 32 years. There were 4 men. Fragments of tumor tissue obtained during surgery were subjected to histological, immunohistochemical (Ki-67 and GFAP) and molecular genetic studies. By real-time PCR method was used to determine the level of the VEGF gene expression and the presence of a mutation in IDH1/IDH2 genes. Histological diagnosis was made in accordance with the classification of tumors of the CNS WHO (2016) and the AFIP atlas (2007).

Results. The tumor most often affected several lobes of the brain (44,4%). The first clinical manifestations of the disease in the vast majority of cases were epileptic and hypertensive syndromes (55,6%). For the proliferative activity index Ki-67 >5% (71,4% of cases) the moderate proliferation of vascular endothelium was noted in 85,7% of cases and the middle/high level of VEGF gene expression (except one case). In patients with low Ki-67 (≤5%), the low level of the VEGF gene expression was determined in 100% cases, the proliferation of the vascular endothelium was absent.

Conclusion. High Ki-67 (>5%), the proliferation of the vascular endothelium, middle/high level of VEGF gene expression are typical attributes of anaplastic astrocytomas. That’s why some GA have features of astrocytomas GIII.

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