ZEB1 expression in tumor tissues in patients with localized and advanced Ewing's sarcoma.

Abstract

e22511 Background: Ewing's sarcoma is the second most common malignant tumor of bones and soft tissues in children and adolescents; it is characterized by an aggressive clinical course and extremely high metastatic potential. The process of its onset is well studied, but the processes of metastasis are of great interest both from a scientific point of view and in clinical practice. Epithelial-mesenchymal transition plays an essential role in tumor progression, and the ZEB1 protein is one of its key regulators. Our purpose was to evaluate the expression of ZEB1 as a prognostic factor in patients with localized and advanced Ewing's Sarcoma (ES) in children and adolescents. Methods: The study included 50 samples of primary ES of various locations. The patients (0-18 years) were divided into groups 1 (localized ES, n = 27) and 2 (advanced ES, n = 23). Rabbit polyclonal antibodies to ZEB1 (Biorbyt Ltd.) at a dilution of 1:200 and the Reveal Polyvalent HRP-DAB Detection System were used for IHC. The percentage and intensity of staining were evaluated: 0, 1+ weak, 2+ moderate, 3+ strong. ZEB1 expression was considered positive when staining was detected in more than 10% (cut-off) tumor cells with intensities of 2+ and 3+. Statistical analysis of results was performed in the Statistica 13.0 program (StatSoftInc., USA). Results: The average ZEB1 expression was in group 1 - 30.0±3.5%, in group 2 - 41.7±11.1%. The maximal accumulation of ZEB1 in the nuclei of tumor cells was observed in patients with advanced ES - 1.4 times (p = 0.248) higher than in patients with localized ES. However, the difference was not statistically significant (the Mann-Whitney U-test, p > 0.05). Conclusions: An IHC analysis revealed a tendency toward increased expression of ZEB1 in patients with advanced ES. However, a more extensive study is needed to evaluate the possible prognostic value of this marker.