Renal cell carcinoma (RCC) is the most common primary renal tumor, 5-year survival of patients with RCC rates of 35 %. According to various data the part of non-diagnostic percutaneous puncture kidney biopsies is high and varies from 5 to 40 %. In RCC diagnostics application of contemporary imaging methods such as CT or MRI doesn’t guarantee 100 % sensitivity and specificity and it ranges from 88 to 96 %. At the moment the role of miRNAs in malignant tumors pathogenesis and the possibility to use them as cancer biomarkers is actively investigated. The aim. The aim of the study was to assess the possibility of miRNA-15a application as a molecular diagnostic biomarker of RCC by measuring its expression in urine. Material and methods. The study enrolled 34 patients with primary RCC. The size of the tumor ranged from 3.5 to 11.4 cm, with median size of 7.2 ± 5.3 cm in the greatest dimension. Surgery was performed in all patients. The main group included patients with pathologically confirmed RCC. A day before surgery a morning urine in volume 100-150 ml was gathered into sterile container in all patients, all samples were cryopreserved at -25 °С. For the reference urine was also obtained and preserved in the same way from 30 healthy volunteers without renal pathology. Isolation of the miR-15а from the urine was performed in patients of the main and control groups followed by determination of its expression by using a reverse transcription and real time polymerase chain reaction.
Results. As a result of the study we observed statistically significant difference (р < 0.05) in the levels of miR-15a expression between the main and control groups: in patients with RCC the mean value was 47.39 ± 24.63 RFU (range - 0,42-99,34 RFU) against 0,04 ± 0,02 RFU (range - 0,01-0,05 RFU) in healthy volunteers. Static analysis didn’t discover in patients with RCC the correlation between size and level of miR-15a expression of the tumor and it was r = 0.35, simultaneously data about tumor-protective role of miRNA-15а that we obtained discords with data of other researchers.
Conclusions. As a result of our study we observed statistically significant difference (р < 0.05) between the mean levels of miR-15a expression in the urine of the patients with RCC and healthy persons. MiR-15a, which was found in urine, may be used as a molecular biomarker of RCC for diagnostics and screening of this disease. The advantage of this diagnostic method is its noninvasiveness and the disadvantage is a necessity in cryopreservation at -25 °С till microRNA isolation. Further investigations with inclusion of larger number of patients with different histological sybtypes of RCC of different grades, benign tumors of kidneys for deeper analysis of the diagnostic value of miR-15a required.
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