LAUSR

e22517 Background: Soft tissue sarcomas (STS) are relatively rare malignant tumors of mesenchymal origin, constituting about 1% of all solid human tumors. About 11% of STS cannot be classified. The relapses of STS are difficult to predict. So, the studying of molecular origin of STS remains to be an actual issue. We analyzed copy number variations (CNVs) of apoptosis-regulating genes and MKI67 gene in primary and recurrent STS. Methods: 32 patients with primary STS and 26 patients with relapses were investigated. Relative CNVs of bax, bcl2, casp3, casp8, casp9, p53, mdm2 and M kI67 were detected with the use of RT–qPCR in fresh frozen tumor and normal tissues obtained while surgical access. Relative Copy Quantitation (RCQ) was accounted with GAPDH and ACTB as reference genes. Results: The frequencies of CNVs of the studied genes in groups of primary and recurrent STS are presented in the table below. A significant change only in the group of primary STS sarcomas was observed for CNV of MDM2, whereas the amplification of the CASP3 and MKI67 genes was characteristic of recurrent sarcomas. CNVs of BAX and CASP8 were significantly more frequent in primary STS. Increased amplification of MDM2 gene, was observed only for liposarcomas among all the others STS. The literature describes amplification of chromosome 12q13-15 where MDM2 gene is localized as a diagnostic feature of liposarcoma which is consistent with our observations [Todorov SS, Kit OI Modern understanding of the morphogenetic features of liposarcomas // Archives of Pathology. 2012. T. 74. №6. p.59-61]. Conclusions: The study showed the potential role of CNV of the BAX, CASP3, CASP8 and MKI67 genes to develop an approach to predicting the course of STS and the effectiveness of the MDM2 gene amplification as an additional marker for liposarcoma molecular classification.[Table: see text]