Extraction and analysis of the exosomal micro-RNA from the urine: new method of the prostate cancer diagnostics

Prostate cancer (PCa) is one of the actual social and medical problems, taking the leading positions in the structure of male diseases. Currently prostate-specific antigen (PSA) evaluation is due to its availability and objectivity the main non-invasive screening and diagnostics modality, being used also post-operatively to control for the treatment efficacy. Specificity and sensitivity of the PSA are not high, this warrants the search for new markers and development of new diagnostic concepts. Micro-RNA (miRNA) are short RNA molecules, regulating expression of more than half of all protein-coding genes at the post-transcriptional level. miRNA are being also excreted into the extracellular matrix and could be detected in most biological fluids. miRNA stability in the extracellular matrix and in the biological fluids is ensured via the complex formation with proteins, lipoproteins and packing into the membrane vesicles, exosomes. The active secretion of the exosomes, containing specific sets of the miRNAs, is described for many cells, including tumor cells. Exosomes, secreted by the tumor cells, show some pathologic effects: inhibition of the anti-tumor immune reactions, speed up of the metastatic spread and resistance to therapeutic substances. miRNA, secreted by the tumor cells, are the main mediators of these effects. Several works were already published aimed at the development of the scientific basis for PCa diagnostic tests, based on the exosomal miRNA detection. Integration of this methods in the clinical practice is complicated because of the absence of simple and reproducible method of exosome extraction from the urine. Development and approbation of this methods was the aim of this work.