Tail spontaneous metastatic mouse model: comparison of metastatic potential of orthotopic and heterotopic models imaged by GFP and RFP protein.

Studies over the past decade have clearly shown that s.c. implant of primary and cultured tumor cells rarely leads to the occurrence of metastatic disease. Orthotopic transplantation of cell suspensions, surgical orthotopic implantation (SOI) of cancer tissue fragments resulted in metastases in many cancer types reaching 100% successful rate. We compared two metastatic models - heterotopic model of Lewis lung cancer and orthotopic B16 mouse melanoma. Both models were syngeneic with high metastatic ratio in C57BL/6 mice after transplantation of cancer cells, by injection into subcutaneous region of mice tail and without surgical intervention. The conclusion is that the localisation of cancer cell injection is a crucial condition for metastatic potential. The site with 100% haematogenous and lymph metastasis rate, after simple injection of cancer cells only, has been defined in mice, without dependence on the genetically predisposition and tumor cell line.