In vivo selection of liver-specific metastasis clones of colon cancer cell line by orthotropic model

Abstract

Purpose: to establish an orthotopic mouse model for colon cancer liver metastasis using human cell lines and to analyze biomolecular characteristics of liver metastasis clones by comparing with parental cell linesMethods: to establish an orthotopic model, BALB/C nu/nu male 4 ~ 6-week-old mice bred in specific pathogen free environment weighing 18 ~ 22 g were used. As parental cell lines, DLD-1, HCT 116, and HT-29 were used. First we injected a suspension containing 107 of cancer cells to the back of mouse. After 3 weeks the xenotropic tumor on the back was harvested and it was implantated to the cecum of mouse. We observed whether orthotopic tumor forms and metastasize to liver. Microscopic histopathologic examination was performed to confirm liver metastasis. Immunohistochemical stain of carcinoembryonic antigen (CEA), matrix metallo-proteinase-1 and 7 (MMP-1, 7), tissue inhibitor of metallo-proteinase-1 (TIMP-1) and vascular endothelial growth factor (VEGF) was performed and their expressions were compared between liver metastasis clone and parental cell lines.Results: of 49 nude mice to which orthotopic implantation was performed, in 44 (89.8%) we could confirm orthotopic tumor grossly and microscopically. HT-29 showed the highest success rate (100%). Various patterns of metastasis were observed with regards to the types of cell lines and liver metastasis was found in 7 mice (14.3%). Of 5 molecular markers VEGF showed significant difference between liver metastasis clone and parental cell lines (P=0.012).Conclusion: an orthotopic colon cancer mouse model showing liver metastasis was successfully established. Using the model we also analyzed the difference of the expressions of molecular markers between liver metastasis clone and parental cell lines. We expect our orthotopic model can be a useful tool for future research regarding colon cancer metastasis