In addition to their potential as tissue-based markers for cancer classification and prognostication, the study of microRNAs (miRNAs) in blood circulation is also of interest. In the present study, we investigated the amounts of three cancer-related miRNAs, miR-21, -141, and -221 in blood plasma of prostate cancer (PCa) patients. A cohort of 51 patients with PCa was enrolled into the study, and miRNAs were measured in two subgroups, with localized/local advanced or metastatic PCa. A group of 20 healthy individuals served as the control group. miRNAs were quantified from the total RNA fraction using 200 μl plasma and the small RNA molecule RNU1A as a control for normalizing the miRNA amounts in circulation. We found similar levels of three miRNAs in healthy subjects with median values of 0.039, 0.033 and 0.04, respectively; (p = n.s.). In the patients, the miRNA levels were higher, with miR-21 being the highest (median, 1.51). The miR-221 levels were intermediate (median, 0.71) while the miR-141 displayed the lowest levels (median, 0.051). The differences between the control group and the patients were highly significant for the miR-21 (p < 0.001; area under the curve (AUC), 88%) and -221 (p < 0.001; AUC, 83%) but not for the miR-141 (p = 0.2). In patients diagnosed with metastatic PCa, levels of all three miRNAs were significantly higher than in patients with localized/local advanced disease where the difference for the miR-141 was most pronounced (p< 0.001; AUC, 75.5%). In conclusion, analysis of miR-21, -141, and -221 in blood of PCa patients reveals varying patterns of these molecules in clinical subgroups of PCa.

Long non-coding RNAs (lncRNAs) are involved in regulating chromatin modifications, gene transcription, mRNA translation, and protein function. We recently reported a high variation in the basal expression levels of a panel of lncRNAs in HeLa and MCF-7 cells and their differential response to DNA damage induction. Here, we hypothesized that lncRNA molecules with different cellular expression may have a differential abundance in secreted exosomes, and their exosome levels would reflect cellular response to DNA damage. MALAT1, HOTAIR, lincRNA-p21, GAS5, TUG1, CCND1-ncRNA in exosomes secreted from cultured cells were characterized. A different expression pattern of lncRNAs in exosomes was seen compared to cells. RNA molecules with relative low expression levels (lincRNA-p21, HOTAIR, ncRNA-CCND1) were highly enriched in exosomes. TUG1 and GAS5 levels were moderately elevated in exosomes, whereas MALAT1--which was the most abundant molecule in cells--was present at levels comparable to its cellular levels. lincRNA-p21 and ncRNA-CCND1 were the main molecules; exosome levels of them best reflect the change of their cellular levels upon exposure of the cells to bleomycin-induced DNA damage. In conclusion, we provide evidence that lncRNAs have a differential abundance in exosomes, indicating a selective loading.

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Exosomes are membranous vesicles containing various biomolecules including lncRNAs which are involved in cellular communication and are secreted from many cells including cancer cells. In our study, investigated the exosomal GAS5 and lincRNA-p21 lncRNA levels in urine samples from 30 patients with prostate cancer (PCa) and 49 patients with benign prostatic hyperplasia. Quantification of lncRNA molecules was performed by real-time PCR. We observed a significant difference in the exosomal lincRNA-p21 levels between PCa and BPH patients whereas the GAS5 levels did not reveal a difference. Our data suggest that the discriminative potential of exosomal lincRNA-p21 levels may help to improve the diagnostic prediction of the malignant state for patients with PCa.

Long non-coding RNAs (lncRNAs) have been shown to be aberrantly expressed in head and neck cancer (HNC). The aim of the present study was to evaluate plasma levels of three lncRNA molecules (lincRNA-p21, GAS5, and HOTAIR) in the treatment response in HNC patients treated with radical chemoradiotherapy (CRT). Forty-one patients with HNC were enrolled in the study. Most of the patients had nasopharyngeal carcinoma (n = 27, 65.9 %) and locally advanced disease. Blood was drawn at baseline and treatment evaluation 4.5 months after therapy. lncRNAs in plasma were measured by semiquantitative PCR. Treatment response was evaluated according to clinical examination, RECIST and PERCIST criteria based on magnetic resonance imaging (MRI), and positron emission tomography with computed tomography (PET/CT) findings. Complete response (CR) rates were 73.2, 36.6, and 50 % for clinical investigation, PET/CT-, or MRI-based response evaluation, respectively. Predictive value of lncRNAs was investigated in patients with CR vs. those with partial response (PR)/progressive disease (PD). We found that post-treatment GAS5 levels in patients with PR/PD were significantly higher compared with patients with CR based on clinical investigation (p = 0.01). Receiver operator characteristic (ROC) analysis showed that at a cutoff value of 0.3 of GAS5, sensitivity and specificity for clinical tumor response were 82 and 77 %, respectively. Interestingly, pretreatment GAS5 levels were significantly increased in patients with PR/PD compared to those with CR upon MRI-based response evaluation (p = 0.042). In contrast to GAS5, pretreatment or post-treatment lincRNA-p21 and HOTAIR levels were not informative for treatment response. Our results suggest that circulating GAS5 could be a biomarker in predicting treatment response in HNC patients.