Comparison of submental tumorigenesis model and axillary tumorigenesis model in nude mice xenotransplanted with human hypopharyngeal carcinoma cells / 第二军医大学学报

ABSTRACT

Objective To establish a submental tumorigenesis model by injecting human hypopharyngeal carcinoma cells to nude mice, and to compare the model with traditional axillary tumorigenesis model. Methods Five-week-old male nude mice were selected and divided into submental tumorigenesis model group (submental group) and axillary tumorigenesis model group (axillary group). Each group was divided into two subgroups by injecting human hypopharyngeal carcinoma cells FADU or HN31, namely sub-FADU, sub-HN31, ax-FADU, and ax-HN31 groups, with 12 nude mice in each group. The nude mice in the submental group were injected with tumor cells in the left side of submental area, and those in the axillary group were injected with tumor cells in the right side of axillary area. The time of tumor formation, tumor volume and body mass of nude mice were measured. The death of nude mice was recorded. After eight weeks, the local tumor growth, infiltration, and organ metastasis such as liver, spleen and kidney of the survival nude mice were examined by ultrasound, and the tumor metastasis was observed by routine H-E staining and immunohistochemical staining. Results On the 7th and 9th days after injection, the tumors were observed in the submental group and the axillary group. On the 33rd day after injection, the tumor volume in the ax-FADU and ax-HN31 groups was significantly bigger than those in the sub-FADU and sub-HN31 groups (P<0.05, P<0.01). The body mass of nude mice in each group reached peak on the 17th to 19th days after injection, and thereafter the body mass in the submental group was gradually decreased and that in the axillary group was still increased. On the 33rd day after injection, the body mass in the ax-FADU and ax-HN31 groups were significantly higher than those in the sub-FADU and sub-HN31 groups, respectively (P<0.01). After eight weeks, there were eight deaths in the sub-FADU group and 10 in the sub-HN31 group, with six mice alive in the submental group; there were six deaths in the ax-FADU group and six in the ax-HN31 group, with 12 alive in the axillary group. There was no significant difference in mortality of nude mice between the four subgroups. Ultrasound and pathological examination showed that four survived nude mice were found with cervical lymph node and liver metastases in the submental group, and only one was found with liver metastases in the axillary group; and the difference between the two groups was statistically significant (P<0.05). There were two pulmonary metastases in the submental group, and one in the axillary group; there was one spleen metastases in the submental group and no spleen metastases in the submental group; and there were no significant differences between the two groups. Conclusion Submental tumorigenesis model and axillary tumorigenesis model have their own characteristics. The submental tumorigenesis model has shorter tumorigenesis time, higher local invasion and higher distant metastasis rate, and is suitable for studying the invasiveness and metastasis of tumor in vivo. The axillary tumorigenesis model has larger volume of tumor, less injury to the adjacent organs and tissues, longer survival time and lower distant metastasis rate, and is suitable for the study of the characteristics of tumor cells.