Human marrow stromal cells secrete microRNA-375-containing exosomes to regulate glioma progression

It is well established that human marrow stromal cells (hMSCs) can directly migrate towards tumor microenvironments associated with tumor formation and intracellular communication. Gene regulatory networks in tumors may be targeted by microRNAs (miRNAs), especially those derived in exosomes from hMSCs. However, the potential functional roles of hMSCs in glioma cell growth still remain controversial. Therefore, this study aimed at exploring the regulatory mechanisms of hMSC exosomal microRNA-375 (miR-375) in glioma. Microarray analysis was used to initially screen out glioma-related genes. The interaction between miR-375 and solute carrier family 31 member 1 (SLC31A1) was confirmed by dual-luciferase reporter gene assay. miR-375 and SLC31A1 expression in glioma cells were determined. Glioma cells were initially exposed to exosomes derived from hMSCs treated with miR-375. Subsequently, the rates of proliferation, migration, invasion and apoptosis were determined in glioma cells using in vitro assays. The effects of exosomal miR-375 from hMSCs on tumor growth in vivo were also measured using xenograft tumor in nude mice. We found that miR-375 and SLC31A1 showed significantly lower and higher expression of glioma cells respectively. Additionally, restored miR-375 expression resulted in suppressed cell proliferation, migration and invasion, and increased apoptosis by targeting SLC31A1. Next, in vitro experiments demonstrated that hMSC-derived exosomes overexpressing miR-375 promoted apoptosis while suppressing proliferation, migration and invasion. Furthermore, in vivo experiments confirmed the negative regulatory effects of hMSC-derived exosomes with overexpressed miR-375. We conclude that exosomal miR-375 from hMSCs inhibits glioma cell progression through SLC31A1 suppression, and ultimately serves as a potential target in the treatment of gliomas.