Abstract: Objective To compare the biological character between the model of human prostate cancer cell DU 145 and 22Rvl utilizing ectopic and orthotopic implantation in nude mice. Methods The human prostate cancer cell DU 145 and 22Rvl were inoculated under orthotopic or ectopic environments separately in nude mice, the mice were were sacrificed at the agonal stage. The tumorigenicity and lymph node metastasis were determined by gross and histological examinations. Results The 22Rvl cells were equally tumorigenic with 10/10 frequency in the prostate and subcutis, they exhibited highly metastasis potentiality with 9/10 lymph node metastasis after orthotopic implantation in nude mice for 40 days, whereas no lymph node metastasis after ectopic implantation.The DU145 cells were equal tumorigenic with 10/10 frequency in the prostate and subcutis, they exhibited lowly metastasis potentiality with 1/10 lymph node metastasis after orthotopic implantation in nude mice, and no lymph node metastasis after ectopic implantation.Conclusion The lymph node metastasis model established by orthotopic implantation in nude mice is successful, and it may become a valuable model for the study of metastasis mechanism and experimental therapy of prostate cancer.

Key words: Prostate cancer, Metastasis, Orthotopic implantation, Ectopic implantation, Nude mice