Radiotherapy is a curative treatment option in prostate cancer. Nevertheless, patients with high-risk prostate cancer are prone to relapse. Identification of the predictive biomarkers and molecular mechanisms of radioresistance bears promise to improve cancer therapies. In this study, we show that aldehyde dehydrogenase (ALDH) activity is indicative of radioresistant prostate progenitor cells with an enhanced DNA repair capacity and activation of epithelial-mesenchymal transition (EMT

Radiotherapy is a mainstay of curative prostate cancer treatment, but risks of recurrence after treatment remain significant in locally advanced disease. Given that tumor relapse can be attributed to a population of cancer stem cells (CSC) that survives radiotherapy, analysis of this cell population might illuminate tactics to personalize treatment. However, this direction remains challenging given the plastic nature of prostate cancers following treatment. We show here that irradiating prostate cancer cells stimulates a durable upregulation of stem cell markers that epigenetically reprogram these cells. In both tumorigenic and radioresistant cell populations, a phenotypic switch occurred during a course of radiotherapy that was associated with stable genetic and epigenetic changes. Specifically, we found that irradiation triggered histone H3 methylation at the promoter of the CSC marker aldehyde dehydrogenase 1A1 (ALDH1A1), stimulating its gene transcription. Inhibiting this methylation event triggered apoptosis, promoted radiosensitization, and hindered tumorigenicity of radioresistant prostate cancer cells. Overall, our results suggest that epigenetic therapies may restore the cytotoxic effects of irradiation in radioresistant CSC populations. Cancer Res; 76(9);

Background: Prostate cancer is one of the most common male cancers in Western countries and takes the third place in morbidity in Ukraine. It is a highly heterogeneous disease. Aim: To analyze relative expression levels of the TGFB1, IL1B, FOS, EFNA5, TAGLN, PLAU, and EPDR1 genes in malignant and non-malignant prostate tissues. Materials and Methods: Total RNA was isolated from 16 prostate adenomas, 37 prostate adenocarcinomas, and 29 conventionally normal prostate tissues. To analyze relative gene expression levels the quantitative real-time polymerase chain reaction was performed. Results: The significant alterations in the relative expression levels were found in all analyzed sample groups for 4 genes: FOS, EFNA5, IL1B, and TGFB1. We have found that FOS and EFNA5 were more frequently overexpressed in carcinomas with Gleason score ≤ 7, compared with adenomas. On contrary, PLAU expression levels were decreased more frequently in prostate cancers, compared with conventionally normal tissues. Noteworthy, we found positive correlation between IL1B expression level and PSA (for patients with slight PSA increase, no more than 20.0 ng/ml). Conclusion: The EFNA5, FOS, IL1B, PLAU, and TGFB1 genes that showed significant expression alterations in prostate tumors, compared with conventionally normal prostate tissue, may play role in prostate cancer development and should be further investigated.

To detect ETS fusion transcripts in Ukrainian population and to analyze a possible relationship between the ETS fusion transcripts and clinical characteristics of prostate cancer. Methods. Quantitative PCR (q-PCR) was used to analyze the expression of six fusion transcripts at the mRNA level. The amplified products were analyzed by gel electrophoresis and direct sequencing. We analyzed 37 fresh frozen samples of prostate cancer tissues, 37 paired conventionally normal prostate tissue samples and 20 samples of adenomas. Results. Six ETS fusion transcripts of TMPRSS2 with ERG, ETV1, ETV4, ETV5 were analyzed. Only one out of six fusion ETS transcripts was detected in a cohort of 37 Ukrainian patients with prostate adenocarcinoma. The frequency of detection of the TMPRSS2-ERG fusion transcript in prostate cancer tissues was 56.8 %. The TMPRSS2-ERG expression was also detected in 16 normal prostate tissue samples (43.2 %) and in 4 prostate adenoma samples (20 %). No correlation was found between the frequency of the TMPRSS2-ERG in carcinoma samples and clinical characteristics of the samples. However, an analysis of relative gene expression in all the investigated groups has shown the altered TMPRSS2-ERG expression in some groups with different Gleason scores of prostate adenocarcinoma compared to adenomas and normal tissue samples. The most elevatedTMPRSS2-ERG expression was found in the prostate adenocarcinoma group with the Gleason score > 7. Conclusions. We detected the TMPRSS2-ERG fusion transcript (EF194202.1) in prostate tumor samples as adenocarcinoma (the frequency was 56.8 %) with different Gleason score andя some paired normal prostate tissues as adenoma samples in our group of Ukrainian population. The obtained results show that the TMPRSS2-ERG fusion transcript is present at early stages of cancer development. In the further studies

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