Establishment and evaluation of an animal model for lymph node metastasis of breast cancer

Objective To establish an animal model and evaluation system for lymph node metastasis of breast cancer. Methods A total of 60 female BALB/c mice (6~8 weeks old) were subjected, and then 6 models of lymph node metastasis (n=10) were constructed through injection at different parts in the mice with cell suspension of 4T1 breast cancer cells.Transgenic mice (n=5) of mouse mammary tumor virus-polyoma middle T antigen (MMTV-PyMT) were employed and served as model of spontaneous tumor metastasis.Then the advantages and disadvantages of different lymph node metastasis models were comprehensively evaluated from multiple aspects, such as operability, histomorphology and pathological detection, tumor growth rate and mouse survival. Results Among the 7 metastasis models, 4 models of lymph node metastasis were successfully established.Among them, the PyMT mouse spontaneous tumorigenesis model showed the best clinical reproduction, with a tumorigenesis rate of up to 100%, but had a disadvantage of poor experimental standardization.The hind paw-popliteal lymph node model had the fastest lymph node metastasis, easy operation and high repeatability, and a tumorigenesis rate of 100%, indicating its suitable for lymph node metastasis related research.The thigh subcutaneous-inguinal lymph node model also successfully simulated lymph node metastasis, with simple operation and high repeatability, a tumorigenesis rate of up to 100%, but its metastasis time was slightly longer than the hind paw-popliteal lymph node model.The inguinal lymph node-contralateral lymph node model was also a successful lymph node metastasis model, but with difficult operation, only 50% tumor-bearing rate, and poor repeatability.Lymph node metastasis model was not successfully established in the other 3 tumor-bearing models (under the tongue-internal jugular scapular tongue muscle lymph node model, bone marrow-inguinal lymph node model and right upper back skin-axillary lymph node model) in a short time, with no tumor cells observed in the pathological sections. Conclusion Through the comprehensive comparison of multiple models, mouse hind paw-popliteal lymph node model is the most suitable for conducting related research.