Selective cyclooxygenase (COX)-1 or COX-2 inhibitors control metastatic disease in a murine model of breast cancer.

Using a highly metastatic mammary tumor cell line that expresses both cyclooxygenase (COX) isoforms, we now show that oral administration of either a selective COX-2 inhibitor (celecoxib) or a selective COX-1 inhibitor (SC560) to mice with established tumors results in significant inhibition of tumor growth. Administration of the dual inhibitor, indomethacin, leads to even better growth control. Metastatic capacity is also reduced by treatment of tumor-bearing mice with either COX-1 or COX-2 selective inhibitors. Pretreatment of tumor cells with COX inhibitors also reduces metastatic success, indicating that tumor cells may be a direct target of action by COX inhibitors. Growth of a second cell line, which does not express COX-2 in vivo, is also reduced by celecoxib, implicating both COX-dependent and COX-independent mechanisms.