VEGF-R1/Flt-1 Receptor as a Characteristic of the Angiogenic Phenotype of Uveal Melanoma

Abstract

Thanks to new fundamental data, our understanding of the angiogenesis’ role and its molecular participants has changed. Molecular genetic mechanisms of activation of signaling pathways of proliferation, malignancy, suppression of the tumor cells’ apoptosis, carried out through the interaction of the VEGF molecule with its receptors, have been deciphered. Molecular genetic mechanisms of activation of signaling pathways of proliferation, malignancy, suppression of apoptosis of tumor cells, carried out through the interaction of the VEGF molecule with its receptors, have been deciphered. The doctrine of angiogenesis has changed. Angiogenesis began to be considered in the aspect of the increasing anaplasia mechanism, accelerating proliferation, the formation of a clone of stem tumor cells, highly resistant to chemotherapy and radiation therapy with a high potential for metastasis. It is time to reconsider the role of individual biological markers of angiogenesis in their suitability in predicting disease outcome and evaluating them as a potential target for targeted therapy. In this aspect, uveal melanoma (UM) as a model of an extremely aggressive malignant tumor using its angiogenic phenotype to accelerate hematogenous metastasis is of particular interest. One of the characteristics of the angiogenic phenotype is VEGF-R1/Flt-1. The purpose: to study the expression of the VEGF-R1/Flt-1 receptor as a characteristic of the angiogenic phenotype of UM in correlation with its clinical and morphological indicators and the outcome of the disease. The authors conducted a retrospective study on 98 archival paraffin blocks of the eyes of patients with UM. The following general patterns of Flt expression in UM cells are revealed: Basic expression takes place in the smallest tumor proliferates UM (T1). Moreover, overexpression (IGH-gradation III) of Flt in the nucleus (39.7 %) and cytoplasm (36.3 %) occurred in every third patient with UM in stage T1. The peak of reception for the maximum average percentage of positive cells and the average cellular IGH gradation of expression was recorded at the T2 stage, after which there was a slow decline to the T4 stage. The number of overexpressive Flt in the nucleus and cytoplasm of UM cells increased x 2 times (75.3 %) to the T2 stage. The peak of Flt nuclear expression in terms of the number of immunopositive cells was also recorded at the T2 stage. The authors concluded that VEGF-R1/Flt-1 expression is a very important characteristic of the UM angiogenic phenotype. In the vast majority of UM, there is an expression of the VEGF-R1/Flt-1 receptor in the nucleus and cytoplasm of tumor cells. The revealed correlations of VEGF-R1/Flt-1 expression with the volume and histological type of tumor, disease stage and metastasis allow them to consider Flt-1 an important indicator associated with the pathogenesis and prognosis of uveal melanoma and a potential target for targeted therapy. A prognostic adverse factor in the aspect of the prognosis of the risk of metastases should be considered the index of the ratio Flt C/Flt N ≥ 3.