Clinical application of exosomal microRNAs in peritoneal fluids of gastric cancer patients with peritoneal metastases

The purpose of this study is to explore the exosomal microRNAs obtained from peritoneal fluids of gastric cancer patients, which are specific for peritoneal metastasis （PM） and could be a predictive marker of disease status in PM. Exosomes were isolated from peritoneal fluids of patients of gastric cancer with PM. Presence of isolated extracellular vesicles （EVs） from peritoneal fluid specimens were confirmed using a transmission electron microscope showed that many EVs were approximately 100 nm in diameter, which were equivalent to exosome fractions. We carried out RNA extraction and comprehensive array analysis of exosomal microRNAs and have identified that 86 microRNAs were significantly up- or down-regulated in all 4 specimens and that out of them, miR-323-3p was highly expressed in all 4 cases. In this way, we have established an experimental system for measuring exosomal microRNAs in peritoneal lavage specimens. Next, we plan to apply this analysis for additional peritoneal lavage specimens obtained from gastric cancer patients with or without PM and to identify specific microRNAs, which could be predictive biomarkers for the disease status of PM in gastric cancer