Using the method of massively parallel sequencing, differential miRNA expression profiles in the original and radioresistant variants of HeLa and DU145 cell lines after radiation exposure at the dose of 4 Gy were obtained. Comparative analysis made it possible to identify a group of miRNAs aberrant expression of which reflected the changes in cell metabolism of radioresistant variants that remained across a number of cell generations as compared to the original ones. The obtained results suggest that the role of miRNAs is associated with the maintenance of functional interaction between DNA methyltransferases, Myc transcription factor, and PTEN phosphatase in regulating the activity of PI3K/AKT and MAPK/ERK signaling pathways. This may underlie differences in realization of radioresistance of HeLa and DU145 cells.

A spectrum of differentially expressed microRNAs was determined by the massively parallel sequencing method in normal healthy prostate tissues, in hormone-dependent prostate cancer samples, and in the LNCaP and DU145 cell lines. A set of microRNAs in tumors and prostate cancer (PCa) cell lines was identified on the basis of the changes in expression compared with that in normal prostate tissues. Twenty-seven aberrantly expressed microRNAs were detected in tumor tissues and ten of them showed significant changes in expression in LNCaP and DU145 cells. Seven of them demonstrated the change of the expression in the same direction in all the tumor samples as well as in the PCa cell lines. The expression of miR-148a changed in DU145 cells in the opposite direction compared with that in LNCaP cells and tumors. The expression of let-7c, let-7b, miR-99a, miR-125b-2, miR-100, miR-10a, and miR-31 was reversed in DU145 cells compared with LNCaP cells. However, these microRNAs exhibited no significant changes in expression in tumors. It turns out that the target of miR-148a, let-7b, and microRNAs, included in the miR-99a/let-7c/miR-125b-2 cluster, the expression of which increased in LNCaP cells and decreased in DU145 cells, is the insulin-like growth factor receptor gene 1 (IGF1R). The obtained data make it possible to assume that the differences in the effect of microRNAs in cell lines are connected with their repressive influence on IGF1R expression in hormone-sensitive LNCaP cells and an absence of such influence in the hormone-independent DU145 cell line.

Using multiple parallel sequencing on Illumina platform, we identified eight microRNAs that showed significant opposite changes of gene expression in cells of the hormone-sensitive LNCaP prostate cancer cell line and in cells of the hormone-resistant DU-145 cell line, in comparison to the microRNA expression in the normal prostate tissue cells. We found that the insulin-like growth factor 1 receptor (IGF1R) gene is a target of five microRNAs whose expression is increased in LNCaP cells and reduced in DU-145 cells.

Using affinity chromatography, two-dimensional electrophoresis, and MALDI-TOF mass spectrometry, plasminogen isoforms were separated and identified in blood plasma. Healthy donors and patients with prostate cancer in various stages of development were included in the studied sample. With the development of prostate cancer, four additional specific plasminogen isoforms are registered in blood plasma; they are characterized by lower molecular weights and higher pI values compared to isoforms found in the control group.