Abstract: Background and purpose: In recent years, many studies have showed that elemene liposome is widely used in the treatment of digestive tract tumors, malignant pleural effusion and ascites. This study combined in vitro and in vivo experiments to observe the inhibitory effect of elemene liposome on the growth of human gastric cancer and the HGC-27 cell line. Methods: In order to screen the optimum concentration of elemene liposome, machine vision automatic live cell observation analysis system (Cell-IQ) was applied to detect the best inhibitory effect on human gastric cancer cell line HGC-27, and the flow cytometry was applied to further detect the apoptosis of HGC-27 treated with elemene liposome. The model of human gastric cancer peritoneal metastasis in nude mice was established to investigate the intervention of elemene liposome and cisplatin (DDP) on peritoneal cancer index (PCI). CD31 marker of tumor microvessel density (MVD) and the expression of vascular endothelial growth factor (VEGF) in tumor tissues were investigated to explore the mechanism underlying the inhibitory effect on peritoneal metastasis of HGC-27 cells in nude mice. Results: Cell-IQ analysis showed that the inhibitory effect of elemene liposome on HGC-27 presented in a positive concentration-dependent manner, which could not be further enhanced when the concentration exceeded 100 μg/mL with the best reaction time between 4 and 19 hours. Flow cytometry showed that the early apoptosis rate was 45% in the elemene liposome group and only 0.019% in the control group. The early apoptosis rate was significantly higher in treatment group than that in control group (P<0.05). PCI was significantly lower in the group treated with elemene liposome plus DDP than that in control group (P<0.05) in the peritoneal metastasis of gastric cancer nude mice model. The expression of CD31-MVD and VEGF was not significantly different between the treated and control groups (P>0.05). Conclusion: Elemene liposome can inhibit human gastric cancer cells at the optimal concentration of 100 μg/mL with the best reaction time between 4-19 hours. Elemene liposome has a clear preventive effect on peritoneal metastasis of human gastric cancer in nude mice. Induction of apoptosis in gastric cancer cells may be the main mechanism underlying the inhibitory effect of elemene liposome on human gastric cancer cells.

Key words: Elemene liposome, Gastric cancer, Peritoneal metastasis, HGC-27, Cell-IQ, Apoptosis