Abstract 2905: The relationship between peritoneal dissemination of gastric cancer & exosome

Introduction: In recent years, studies of exosomes have progressed rapidly, suggesting a connection to various physiological functions and pathogenesis. The exosomes are small extracellular vesicles with a diameter of 30 to 100 nm surrounded by lipid bilayers, and are attracting attention as a new cell-cell communication medium for carrying lipids, proteins, RNA, etc. in vivo. In addition, in exosomes released by cancer cells, it contains a large number of molecules related to angiogenesis and immunosuppression. It is believed to contribute to building microenvironments suitable for cancer cell growth and promoting cancer progression. Therefore, we focused on exosomes derived from gastric cancer cells, the action of gastric cancer cells, further constructed a gastric cancer peritoneal dissemination mouse model, the action of exosomes in gastric cancer peritoneal metastasis mechanism was examined in vitro, in vivo, respectively. Method: Exosome Isolation Kit was used to extract exosomes from each gastric cancer cell line MKN-1, MKN-45, MKN-45 GFP. The determination of exosomes was carried out using Nano-drop®. Cell adhesion in exosome-treated and non-administered groups were analyzed by colony forming assay. Cell proliferation ability was analyzed using cell proliferation assay method. In vivo, we examined whether the degree of peritoneal dissemination was made using live cell imaging using fluorescent cells. MKN-45 GFP was intraperitoneally administered to BALB/c-nu mice. On days 0, 5, 10, 15, 20, groups were prepared in which 25 µg/500 µl of exosome was administered intraperitoneally and groups in which the same amount of PBS was administered intraperitoneally. In addition, MKN-45 GFP was subcutaneously injected into BALB/c-nu mice to create MKN-45 GFP tumors, which were divided into small horns and transplanted to the stomach walls of BALB/c-nu mice. In the same way as the previous method, we prepared a group in which 25 µg/500 µl exosome was intraperitoneally administered on days 0, 5, 10, 15, 20 and a group in which the same amount of PBS was intraperitoneally administered. We performed a visual comparison of transplanted cancer cells and peritoneal dissemination of cancer. Results and Discussion: The results of the colony forming assay method suggest that exosomes derived from gastric cancer cells have the effect of promoting colony formation ability of cancer cells. We evaluate the results of peritoneal seeding model mice in this study, and further p