Abstract: Objective To explore differential biological properties of local and metastatic human gastric cancer after orthotopic inplantation in nude mice and SCID mice. Methods MKN-45 human gastric carcinoma cell line was inoculated subcutaneously in nude mice to develop s.c. growing tumors. Orthotopic implant model simulating human gastric cancer was established by suturing histologically intact human tumor tissue on the stomach walls of nude mice and SCID mice. Subsequently, we observed the take rate of the orthotopic tumors and their biological properties of tumor growth and metastasis. Results ① 100% tumor take rates were observed in both strains of mice.② The tumor volume in the stomach of nude mice was 2884±1337 mm³,the metastases of local and distant lymph nodes were noted in 67% of the mice, the rates of liver, lung and diaphragm metastases were 83%, 33%, 8%, respectively.③ The tumor volume in the stomach of SCID mice was 4582±1326 mm³ （P＜0.05）.The incidences of liver metastases in SCID mice were almost similar to those of nude mice which were 90% （P＞0.05）. In contrast, there was a significant increase in the incidences of lung and diaphragm metastases, which were 100% （P＜0.01） and 60% （P＜0.05），respectively. Conclusions The results suggest that SCID mice are more suitable for establishment of orthotopic implant models for human gastric carcinoma compared with nude mice.

Key words: Human gastric carcinoma, Nude mice, SCID mice, Orthotopic implantation, Biological properties