MiR-410-3p suppresses primary gastric cancer and exosomes regulate endogenous expression of miR-410-3p.

MicroRNAs play significant roles in cancer initiation and progression. Exosomes are important extracellular vesicles for transporting molecules to distant sites. This study aims to investigate the functional roles of miR-410-3p in primary gastric cancer, as well as the roles of exosomes in regulating expression of miR-410-3p. In this study, forty-seven pairs of human gastric cancer tissue samples were collected. Endogenous expression of miR-410-3p in tissue samples and cell lines, and expression of exosomal miR-410-3p in cell culture medium were evaluated by RT-qPCR. Functional assays including cell proliferation assay by MTT, cell migration and invasion assay by transwell, and cell adhesion assay were performed. Targets of miR-410-3p were screened. Cell culture medium of culturing cell lines established from stomach (AGS and BCG23) was applied for culturing cell lines established from other sites (MKN45 and HEK293T). It was found that miR-410-3p was significantly downregulated in gastric cancer. Overexpression of miR-410-3p inhibited gastric cancer cell proliferation, migration, and invasion. MiR-410-3p mimic enhanced cell adhesion. HMGB1 was a target of miR-410-3p in primary gastric cancer. Expression of exosomal miR-410-3p in cell culture medium was dramatically higher than its endogenous expression. Exosomes from cell culture medium of AGS or BCG23 regulated endogenous expression of miR-410-3p in MKN45. In conclusion, miR-410-3p functioned as a tumor suppressor in primary gastric cancer. MiR-410-3p was higher expressed in exosomes of cell culture medium than its endogenous expression in cells. Endogenous expression of miR-410-3p in a distant site could be regulated by exosomes from the original site.