Integration of exosomal miR-106a and mesothelial cells facilitates gastric cancer peritoneal dissemination

Abstract

BackgroundMetastatic organotropism is considered the end stage of malignancy with the mechanism still have some mysteries that have not been disclosed. Although the role of miR-106a is well studied, its involvement in the formation of peritoneal metastasis transported by exosomes is less discussed. MethodsGastric cancer (GC)-derived exosomes were identified by transmission electron microscopy and the integration with peritoneal mesothelial cells (PMC) was confirmed by PKH-26 staining. Cell phenotype was assessed by EdU and flow cytometry. MiR-106a and its targets were authenticated by luciferase reporter assay. The mesothelial-to-mesenchymal transition (MMT) and extracellular matrix (ECM) degeneration were determined and morphological transformation was measured by transwell assay. Immunodeficient mouse was conducted to investigate the tumorigenesis and tumor growth. The final was tissue analysis. ResultsMiR-106a enrichment in GC-exosomes can be delivered and integrated into PMC to establish a proper pre-metastatic niche (PMN). We found that PMC could internalize exosomal-miR-106a and lead to increased apoptotic rate and decreased proliferative vitality. The direct target Smad7 and TIMP2 were proved to be effectively reduced by translocation of exosomal miR-106a. We confirmed that exosomal miR-106a was able to induce MMT and accelerate ECM through targeting Smad7 and TIMP2 to activate TGF-β pathway. Animal model investigated that the tumorigenesis and tumor growth could be influenced by exosomes, and exosomal-miR-106a could promote the formation of xenograft tumor. Tissue analysis verified the ectopic miR-106a expression in gastric cancer metastasis. ConclusionOur data suggest that exosomal miR-106a facilitates gastric cancer peritoneal dissemination by integrating PMC to destroy mesothelial barrier.