Abstract
Peritoneal metastasis is a primary metastatic route for gastric cancers, and the mechanisms underlying this process are still unclear. Peritoneal mesothelial cells (PMCs) undergo mesothelial-to-mesenchymal transition (MMT) to provide a favorable environment for metastatic cancer cells. In this study, we investigated how the exosomal miR-21-5p induces MMT and promotes peritoneal metastasis. Gastric cancer (GC)-derived exosomes were identified by transmission electron microscopy and western blot analysis, then the uptake of exosomes was confirmed by PKH-67 staining. The expression of miR-21-5p and SMAD7 were measured by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot, and the interactions between miR-21-5p and its target genes SMAD7 were confirmed by Luciferase reporter assays. The MMT of PMCs was determined by invasion assays, adhesion assays, immunofluorescent assay, and western blot. Meanwhile, mouse model of tumor peritoneal dissemination model was performed to investigate the role of exosomal miR-21-5p in peritoneal metastasis in vivo. We found that PMCs could internalize GC-derived exosomal miR-21-5p and led to increased levels of miR-21-5p in PMCs. Through various types of in vitro and in vivo assays, we confirmed that exosomal miR-21-5p was able to induce MMT of PMCs and promote tumor peritoneal metastasis. Moreover, our study revealed that this process was promoted by exosomal miR-21-5p through activating TGF-β/Smad pathway via targeting SMAD7. Altogether, our data suggest that exosomal miR-21-5p induces MMT of PMCs and promote cancer peritoneal dissemination by targeting SMAD7. The exosomal miR-21-5p may be a novel therapeutic target for GC peritoneal metastasis.
Highlights
Gastric cancer (GC) is one of the most common cancers worldwide, with more than 50% of cases occurring in Eastern Asia[1]
As we have speculated that exosome-induced mesenchymal transition (MMT) may play an important role in peritoneal metastasis, we firstly evaluated the different abilities to induce MMT among four GC cell line-derived and GES-1 cellsderived exosomes in vitro (GES-1 cells-derived exosomes were used as the negative control)
We used lentiviral vectors LV-SMAD7 to transfect HMrSV5 cells which have been transfected with miR-215p-mimics vector and miR-21-5p-inhibitor HMrSV5 cells were transfected with lentiviral vectors sh-SMAD7
Summary
Gastric cancer (GC) is one of the most common cancers worldwide, with more than 50% of cases occurring in Eastern Asia[1]. GC has become the second leading cause of cancer deaths[2]. According to the national survey, the number of new GC cases in China in 2015 was 679,000, with 498,000 deaths. Radiotherapy, chemotherapy and biological treatment have been adopted so far, the 5-year survival rate of GC is still poor, partially on account of up to 50% of GC patients. A monolayer of peritoneal mesothelial cells (PMCs) that lines the peritoneal cavity has been reported to be able to undergo mesothelial-to-mesenchymal transition (MMT), an important morphological change in peritoneal metastases[5]. MMT of PMCs was observed in peritoneal dissemination and promoted early cancer metastasis[6,7,8,9].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
