Suppressive effects of nimesulide, a selective inhibitor of cyclooxygenase-2, on azoxymethane-induced colon carcinogenesis in mice

The effects of nimesulide, a selective inhibitor of cyclooxygenase-2(COX-2) on azoxymethane (AOM)-induced colon carcinogenesis wereinvestigated in mice. AOM at a dose of 10 mg/kg body wt was administered tomale ICR mice once a week for 6 weeks. The animals were fed on AIN-76Apowder diet containing nimesulide at doses of 200 or 400 p.p.m., startingthe day before the first carcinogen treatment until the end of theexperiment, at week 30. Administration of nimesulide reduced the incidenceof colon carcinomas to 32 and 25% for the AOM + 200 and 400 p.p.m.nimesulide groups, respectively, compared with the AOM + basal diet group(50%). Multiplicities of colon carcinomas in the 200 and 400 p.p.m.nimesulide-treated groups were 0.70 +/- 0.28 and 0.35 +/- 0.11,respectively, being significantly smaller than the AOM alone value (1.79+/- 0.47). The sizes of the colon carcinomas in the nimesulide-treatedgroups were also decreased. No significant influence on liver and lungtumor development was apparent. Thus, nimesulide exerted a suppressiveeffect on AOM-induced colon carcinogenesis in mice.