Orthotopic implantation of a colon cancer xenograft induces high expression of cyclooxygenase-2

The aim of the present study is to investigate the relation of cyclooxygenase (COX)-2 with liver metastasis. Pieces of human colon cancer xenograft were implanted orthotopically (CI), as well as intraperitoneally, and subcutaneously. Liver metastasis developed most frequently, and the COX-2 expression of both mRNA and protein of the tumors was the most dominant in the CI group. In contrast, the expression of COX-1 or vascular endothelial cell growth factor mRNAs had no significant differences among the groups. The intensity of COX-2 mRNA was negatively correlated with the apoptotic index. In conclusion, COX-2 plays an important role in organ-specific metastasis of the colon cancer.