ИСТИНА

Background. Renal cell carcinoma (RCC) is the second most common cancer among uronephrological cancers that characterizes as highly aggressive and invasive with high frequency of metastasis. RCC is also lack in specific symptoms, therefore it is difficult to detect and it is usually diagnosed at late stage of disease in routine screening or during examinations for another pathology. Methods of early specific RCC diagnostic are poorly developed. Recent advances in diagnostic biomarkers of RCC are based on detection of tumor-associated proteins (TAAs) or nucleic acids in blood flow or in tumor itself. However, tumor heterogeneity and complexity of the biopsy procedure may be limiting factors. Contrariwise, blood is less invasive to obtain, but biomarkers undergo degradation by circulating nucleases and proteases, thereby their signals is damped in blood assays. Another type of biomarkers that could be applied for RCC diagnosis is autoantibodies against aberrantly expressed proteins. In contrast to TAAs and nucleic acids, antibodies are far more stable in blood and antibody response is early and enduring. The basis for antibody response against tumor is aberrant expression of TAAs by that tumor. Several TAAs were proposed to be aberrantly expressed in RCC and cancer-retinal proteins are one of that group of proteins. In this study, we analyzed whether aberrant expression of cancer-retinal protein visual arrestin can be detected in RCC and whether autoantibodies against visual arrestin will be produces. Methods. Blood sera from 33 patients with diagnosed RCC and tumor tissue samples from 39 patients with diagnosed RCC or renal oncocytoma were collected. Western blot analysis was performed to detect autoantibodies against visual arrestin in patients’ sera. To reveal the presence of vusual arrestin in renal tumor cells, immunohistochemical assay of tumor sections was performed. Results. Western blot analysis revealed, that serum samples from 25 out of 33 (75,7%) patients with RCC produces immunostaining of band corresponding to visual arrestin. Immunohistochemical assay of 39 renal tumor tissue samples revealed arrestin-positive reaction in 3 out of 11 (27,3%) samples of clear cell RCC, in 4 out of 5 (80%) samples of chromophobe RCC, in 4 out of 6 (66,6%) samples of papillary RCC, and in 9 out of 10 (90%) samples of renal oncocytoma. Overall, 62,5% of tested by immunohistochemistry renal tumor tissue samples have shown arrestin-positive reaction, among which RCC sections were arrestin-positive in 50% of their cases. Conclusion. Expression of visual arrestin can be detected frequently in different malignant renal tumor cells. Moreover, it was found that RCC patients often produce autoantibodies against aberrantly expressed visual arrestin. Taking in account such findings and advantages of antibodies over TAAs and nucleic acids as biomarkers, autoantibodies against visual arrestin could be promising biomarker for diagnostic and/or early RCC detection.