The advent of Next Generation Sequencing technologies brought with it the discovery of several microRNA (miRNA) variants of heterogeneous lengths and/or sequences. Initially ascribed to sequencing errors/artifacts, these isoforms, named isomiRs, are now considered non-canonical variants that originate from physiological processes affecting the canonical miRNA biogenesis. To date, accurate IsomiRs abundance, biological activity, and functions are not completely understood; however, the study of isomiR biology is an area of great interest due to their high frequency in the human miRNome, their putative functions in cooperating with the canonical miRNAs, and potential for exhibiting novel functional roles. The discovery of isomiRs highlighted the complexity of the small RNA transcriptional landscape in several diseases, including cancer. In this field, the study of isomiRs could provide further insights into the miRNA biology and its implication in oncogenesis, possibly providing putative new cancer diagnostic, prognostic, and predictive biomarkers as well. In this review, a comprehensive overview of the state of research on isomiRs in different cancer types, including the most common tumors such as breast cancer, colorectal cancer, melanoma, and prostate cancer, as well as in the less frequent tumors, as for example brain tumors and hematological malignancies, will be summarized and discussed.

Non-alcoholic fatty liver disease (NAFLD) is considered a relevant liver chronic disease. Variable percentages of NAFLD cases progress from steatosis to steatohepatitis (NASH), cirrhosis and, eventually, hepatocellular carcinoma (HCC). In this study, we aimed to deepen our understanding of expression levels and functional relationships between miR-182-5p and Cyld-Foxo1 in hepatic tissues from C57BL/6J mouse models of diet-induced NAFL/NASH/HCC progression. A miR-182-5p increase was detected early in livers as NAFLD damage progressed, and in tumors compared to peritumor normal tissues. An in vitro assay on HepG2 cells confirmed Cyld and Foxo1, both tumor-suppressor, as miR-182-5p target genes. According to miR-182-5p expression, decreased protein levels were observed in tumors compared to peritumor tissues. Analysis of miR-182-5p, Cyld and Foxo1 expression levels, based on datasets from human HCC samples, showed results consistent with those from our mouse models, and also highlighted the ability of miR-182-5p to distinguish between normal and tumor tissues (AUC 0.83). Overall, this study shows, for the first time, miR-182-5p overexpression and Cyld-Foxo1 downregulation in hepatic tissues and tumors from a diet-induced NAFLD/HCC mouse model. These data were confirmed by the analysis of datasets from human HCC samples, highlighting miR-182-5p diagnostic accuracy and demonstrating the need for further studies to assess its potential role as a biomarker or therapeutic target.

Background/Objectives: Pancreatic cancer (PC) is among the most aggressive malignancies, often diagnosed at late stages. MicroRNAs (miRNAs) and proteins released from the tumor microenvironment into body fluids represent promising non-invasive biomarkers for early cancer detection. In this study, we took advantage of an innovative ultrasound (US)-based instrument (SonoWell^®, Inno-Sol srl, Rome, Italy) to treat PC cells in order to promote and amplify the release of molecules, with the aim of identifying novel putative diagnostic PC biomarkers. Methods: Three human pancreatic adenocarcinoma cell lines (T3M-4, Panc02.03, and PaCa-44) and a non-cancerous pancreatic epithelial line (HPanEPic) were subjected to US using the SonoWell instrument. MiRNAs released in the supernatants were profiled by TaqMan-based qRT-PCR microfluidic cards, while proteins were analyzed by antibody arrays. Publicly available datasets of circulating miRNAs in PC patients were also reviewed. Results: Expression levels of 22 miRNAs in T3M-4 cells, 11 in Panc02.03, and 22 in PaCa-44, none of which were identified in the non-cancerous cell line profiling, were increased in the supernatant of US-treated as opposed to control cells. Among the statistically significant miRNAs or miRNAs common to at least two tumor cell lines, the expression levels of miR-155-5p, miR-320a, miR-32-5p, and miR-93-5p were also found to be significantly upregulated in sera from PC patients compared to the results for healthy controls. With regard to proteins released after sonication, several molecules were identified as candidate biomarkers in cancer US supernatants (Beta-2 microglobulin, CA125, CA19-9, CEA, CRP, Galectin-3, TIMP-1, uPA, and VEGF-A). Conclusions: We demonstrated that US-mediated sonoporation can promote and amplify the release of small molecules, miRNAs, and proteins into cell culture supernatants for consideration as putative biomarkers, thus encouraging further studies aimed at directly validating their expression levels in sera/plasma from PC patients and at deepening their role in the treatment of PC.