Evaluation of Novel Circulating Extracellular Vesicle-packaged microRNAs in Breast Cancer: a Potential Role for miR-128 and miRNA-27a

Purpose: Extracellular vesicle (EV)‑derived microRNAs (miRNAs) are a class of circulating miRNAs located in the plasma that are are now considered the next generation of cancer “theranostic” tools, with a strong clinical relevance. Although the potential role of EV-packaged miRNAs in breast cancer diagnosis has been widely reported, further studies are still demanded to address this challenging issue. The present study examined the expression profiles of EVs and circulating miRNAs with the aim of identifying novel miRNA signatures in breast cancer, and verify their diagnostic accurancy. Methods: Circulating EVs were isolated from helathy volunteers, and breast cancer patients and characterized by Transmission Electron Microscopy (TEM), Nanoparticle Tracking Analysis (NTA), and protein marker expression. Assessment of EV-miRNAs was performed in a screening and a validation cohort by RNA-seq and qRT-PCR analyses, respectively. Bioinformatic analysis was performed to uncover significantly enriched biological processes, molecular functions and pathways. A comprehensive literature search was conducted to outline the role of the identified miRNAs in breast cancer. Results: A total of two miRNAs, including miRNA‑128, and miRNA27a, were found to be significantly down-regulated in breast cancer-derived EVs compared to healthy individuals. Metacore GO processes, Molecular Functions and Localizations on target genes of the two deregulated miRNAs indicated roles in regulation of cellular cycle and migration. Moreover, ROC analyses highlighted the ability of miRNA‑128, and miRNA27a in distinguishing breast cancer cases from non-cancer controls. According to other reports, levels of EV-derived miRNAs did not not associate with circulating plasma levels, indicating how the EV-incorporated and whole plasma miRNA profiles could be clearly different. These results were subsequently compared with evidence from studies included in the final systematic review. Conclusion: Our findings unraveled a potential role for serum EV-derived miRNA‑128, and miRNA27a in breast cancer, adding these two miRNAs to the list of multiple biomarkers that could be exploited in the clinic to diagnose breast cancer. -------------------------- *This submission consists of healthy controls only