Combination of cyclooxygenase-2 inhibitors and oxaliplatin increases the growth inhibition and death in human colon cancer cells

Abstract

The cyclooxygenase-2 (COX-2) protein is highly expressed in a variety of human cancers and has been reported to promote tumor growth. Non-steroidal anti-inflammatory drugs such as etodolac and celecoxib have been shown to inhibit COX-2 activity and may play a role in the chemoprevention of cancer. Oxaliplatin is a third-generation platinum compound that exhibits a different spectrum of activity compared with cisplatin. Other cisplatin-resistant tumors can still respond to oxaliplatin. However, the anticancer ability of the combination of COX-2 inhibitors and oxaliplatin is still unknown. In this study, we investigated the effects of combination of COX-2 inhibitors and oxaliplatin on the cell growth and survival in human colon cancer cells. Treatments with etodolac (0.3–0.5 mM) or celecoxib (20–80 μM) for 24 h concentration-dependently induced the cytotoxicity in the RKO colon carcinoma cells. Etodolac and celecoxib did not alter the COX-2 protein levels but inhibited its enzyme activity to reduce prostaglandin E 2 production. Furthermore, the cell survival was concentration-dependently decreased following oxaliplatin (1–100 μM, 24 h) treatment. Combination of oxaliplatin and etodolac additively increased the death and growth inhibition of RKO cells. Survivin, an inhibitor protein of apoptosis, mediates anti-apoptosis and promotes cell division in cancer cells. Oxaliplatin or COX-2 inhibitors significantly decreased the levels of survivin proteins. Moreover, survivin proteins were markedly diminished following co-treatment with oxaliplatin and etodolac. Together, this is the first report that combination of COX-2 inhibitors and oxaliplatin can increase the reduction of survivin protein expression, growth inhibition, and death in human colon cancer cells.