ANTIOXIDANT STATUS IN TISSUES OF GD2-POSITIVE SOFT TISSUE SARCOMA IN CHILDREN

Introduction. GD2 disialogangliosides are expressed in soft tissue sarcoma, can inhibit specific cellular cytotoxicity, suppressing cytolytic activity. The antioxidant system of cells maintains homeostasis of reactive oxygen species, violation of the balance of which is one of the factors of carcino-genesis. Determination of the levels of antioxidant system parameters in children with GD2-positive soft tissue tumors may be promising for predicting therapy, as well as contribute to the study of the pathogenesis of these tumors. Aim. To investigate the activity of antioxidant system and lipid peroxidation in GD2-positive soft tissue sarcoma. Material and methods. Tissue homogenates of GD2-positive soft tissue sarcoma (predominantly rhabdomyosarcoma), n=5 (study group), and healthy muscle tissues, n=9 (control group), were used for biochemical studies. The enzyme activity in tissue homogenate was calculated per one gram of protein. Results. Analysis of the obtained data showed that in tumor tissue there was a significant decrease in the concentration of malonic dialdehyde – by 63.5% compared to the control (p≤0.05), which reflects a decrease in the level of lipid peroxidation. In tumor tissues, superoxide dismutase activity was significantly decreased by 31.8% and glutathione peroxidase activity was significantly increased by 14.2% (p≤0.05), while glutathione reductase activity was increased by 34.1%. The increase in glucose-6-phosphate dehydrogenase activity was particularly pronounced – more than 2.5-fold (p≤0.05). The level of reduced glutathione was reduced, but the differences did not reach statistical significance. Conclusion. In the tissue of GD2-positive soft tissue sarcoma, signs of imbalance between prooxidant and antioxidant systems were revealed. The dysregulation of antioxidant defense manifests as suppressed superoxide dismutase activity and depletion of the reduced glutathione pool, coupled with compensatory activation of glutathione cycle enzymes (peroxidase, reductase) and glucose-6-phosphate dehydrogenase. These changes reflect the metabolic adaptation of tumor cells to oxidative stress conditions and may be potential targets for antitumor therapy.