SOLUBLE FORM OF PODOPLANIN IN PATIENTS WITH BONE NEOPLASMS

Introduction. Podoplanin is a mucin-type transmembrane protein involved in the processes of cell migration, angio- and lymphangiogenesis, embry-onic development and metastasis. Its biological activity is realized through interaction with partner proteins (CLEC-2, CD44, galectin-8, etc.). Podoplanin expression is detected in various types of normal cells (lymphatic endothelium, podocytes, follicular dendritic cells), and its increase is associated with a number of malignant neoplasms. Of particular interest is the role of podoplanin in the tumor microenvironment and its potential value as a marker for noninvasive diagnostics. The aim of this work is to study the level of soluble podoplanin in the blood serum of patients with primary bone tumors. Material and methods. The analysis of podoplanin content in the blood serum was performed in 83 patients with malignant bone tumors (MBT), 24 with benign bone tumors (BBT) and 23 healthy donors of the control group. The total group of patients with malignant bone tumors consisted of 19 chil-dren aged 6 to 16 years (median 13 years) and 64 adults aged 19 to 76 years (median 50 years). The serum podoplanin level was measured by en-zyme immunoassay using the Human Podoplanin Elisa Kit (RayBiotech, USA) according to the manufacturer's instructions. The obtained data were pro-cessed using GraphPad Prizm 10.4 software. When comparing the indicators and analyzing their relationships, the nonparametric Mann–Whitney and Kruskal–Wallis tests were used. Differences and correlations were considered statistically significant at p < 0.05. Results. The podoplanin level in the control group of children was significantly higher than the level in adults (median 219.6 ng/ml versus 12.8 ng/ml). In patients with MBT, the podoplanin level was lower compared to the control (especially in children), but the differences did not reach statistical signifi-cance. In the group of adults, a statistically significant decrease in podoplanin was noted in MBT compared to BBT (p = 0.039). ROC analysis showed low diagnostic value of the studied parameter (AUC=0.514 in adults and AUC=0.645 in children). Among patients over 18 years of age, higher podoplanin levels were associated with age under 50 years (p = 0.011). Podoplanin levels were higher in patients with osteosarcoma than with chondrosarcoma (p = 0.071), but the insignificant differences iden-tified were probably due to the age of the patients. In children, no significant correlations were found between podoplanin levels and clinical and mor-phological parameters. Conclusions. Measurement of soluble podoplanin levels in serum has no diagnostic value in patients with MBT. The obtained data highlight the limita-tions of the use of this marker outside the context of tissue expression and indicate the need for further research in this area. The changes in the con-tent of the soluble form of podoplanin that we described depending on age undoubtedly require further study.