The potential for a selective cyclooxygenase-2 inhibitor in the prevention of liver metastasis in human colorectal cancer

In a previous report we noted that cyclooxygenase-2 (COX-2) expression in clinical colorectal cancer is closely related to liver metastasis and survival. The aim of the present study was to clarify the role of COX-2 in liver metastasis and to examine the potential for a selective COX-2 inhibitor as a novel therapeutic agent in the treatment of colorectal cancer. Materials and Methods: COX-2 expression of 6 kinds of human colon cancer cell lines, with various potentials for liver metastasis, were assessed by Western blot and reverse transcriptase polymerase chain reaction (RT-PCR). In human tumor xenografts/severe combined immune - deficient (SCID) mouse, we examined the effects of a selective COX-2 inhibitor (JTE-522) on tumor growth or liver metastasis of HT-29, a highly - metastatic cell line, or on COLO205, a non - metastatic cell line. The effect of JTE-522 on vascular endothelial growth factor (VEGF) expression and the activity of matrix metalloproteinases (MMPs) in HT-29 and COLO205 were assessed by enzyme-linked immunosorbent assay (ELISA) and gelatin zymography, respectively. Results: COX-2 was expressed in all metastatic cell lines but not in the non - metastatic lines. JTE-522 prevented the liver metastasis of HT-29, but not the subcutaneous growth of HT-29 and COLO205 in SCID mice. In vitro, JTE-522 suppressed VEGF expression, but did not affect MMP production in HT-29; an inhibitory effect was not found in COLO205. Conclusion: A selective COX-2 inhibitor of JTE-522, was found to prevent liver metastases of colon cancer by suppressing VEGF expression, and therefore, COX-2 possibly plays an important role in liver metastasis of human colon cancer via the regulation of VEGF expression.