Abstract 2895: Extracellular vesicles derived from mesothelial cells promotes the migration and invasion of gastric cancer cells
Authors: Sugimoto Atsushi , Yashiro Masakazu , Okuno Tomohisa , Miki Yuichiro , Tsujio Gen , Yamamoto Yurie , Sera Tomohiro , Kushiyama Shuhei , Nishimura Sadaaki , Kuroda Kenji , Togano Shingo , Ohira Masaichi 
Published: July 2021

Abstract
Background: Peritoneal dissemination is one of common causes of poor prognosis of patients with gastric cancer (GC). The mechanism of peritoneal metastasis has not been fully elucidated. Recent studies have reported that extracellular vesicles (EVs) play an important role for the intercellular communication in GC microenvironment. The peritoneal dissemination possesses some intercellular communication steps between cancer cells and hostile cells including peritoneal mesothelial cells (PMCs), however, the effect of EVs derived from PMCs on GC cells has not been validated. In the present study, to clarify the intercellular communication we evaluated the effect of EVs from PMCs on the proliferation, migration and invasion of GC cells.
Materials and Methods: Four GC cell lines (OCUM12, NUGC3, MKN45, MKN74) and 4 PMCs cell lines were used. PMCs cell lines were primary cultured from ascites of gastric cancer patients. The EVs derived from PMCs were isolated from conditioned medium of PMCs by ultracentrifugation. The EVs derived from PMCs were confirmed by the transmission electron microscope (TEM) using uranyl acetate and the western blotting using EV markers such as CD9, CD63, and CD81. The EVs derived from PMCs were fluorescently labelled using PKH26 and the uptakes of EVs were viewed under a fluorescence microscope. The effect of EVs from PMCs on the proliferation, migration and invasion of GC cells was evaluated by MTT assay, wound healing assay and Matrigel invasion assay respectively.
Results: The EVs derived from PMCs showed typical morphology of EVs by TEM, and were positive for EV markers such as CD9, CD63, and CD81 in western blotting. The EVs derived from PMCs significantly suppressed the proliferation of GC cells. On the other hand, the EVs derived from PMCs significantly promoted the migration of OCUM12 and NUGC3 cells, but not MKN45 and MKN74 cells. Furthermore, The EVs derived from PMCs significantly promoted the invasion of OCUM12 and NUGC3 cells. PKH26 labelled EVs derived from PMCs were found in cytoplasm of OCUM12 and NUGC3 cells.
Conclusion: The EVs derived from PMCs significantly promoted the migration and invasion of GC cells. The EVs derived from PMCs might be one of factors which associate with the intercellular communication steps in peritoneal dissemination possesses in GC.
Citation Format: Atsushi Sugimoto, Masakazu Yashiro, Tomohisa Okuno, Yuichiro Miki, Gen Tsujio, Yurie Yamamoto, Tomohiro Sera, Shuhei Kushiyama, Sadaaki Nishimura, Kenji Kuroda, Shingo Togano, Masaichi Ohira. Extracellular vesicles derived from mesothelial cells promotes the migration and invasion of gastric cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2895.