An Animal Model of Colorectal Cancer Liver Metastasis With a High Metastasis Rate and Clonal Dynamics.

Background: Various animal models have been introduced into the study of liver metastasis of colorectal cancer, but they have not been compared under the same conditions. The aim of this study was to identify an optimized mouse model that showed a high rate of hepatic metastasis and expression of clonal dynamics.

Materials And Methods: Athymic nude mice (n=30) were divided into two equal groups for the creation of a splenic injection model (SIM) and surgically orthotopic implantation model (SOIM) of liver metastasis of colorectal cancer using HCT116 cells. Hepatic metastasis was confirmed by gross and microscopic examinations. Expression of MET transcriptional regulator MACC1 (MACC1) in colon cancer cell lines and metastatic tumors in the group with a higher liver metastasis rate was confirmed by quantitative reverse-transcription-polymerase chain reaction.

Results: The observation time was significantly shorter for SIM than for SOIM (33.0±6.8 vs. 41.2±7.2 days, p<0.001). The rate of hepatic metastasis was significantly higher in SIM than in SOIM (76.9% vs. 38.4%, p=0.038). MACC1 was expressed in Colo201, HCT116, HT29, LS513, SW620, and WiDr cells but not in SW480 cells. All hepatic metastases in SIM mice expressed MACC1, and metastatic HCT116 cells had significantly greater expression than did the original HCT116 cells (p<0.001).

Conclusion: With a higher rate of hepatic metastasis with clonal dynamics in a shorter observation time than the SOIM, SIM appears to be a good animal model for identifying new targets and in drug development for colorectal cancer liver metastasis. SOIM should also be considered for the study of the full steps of metastasis.