Sulindac and a cyclooxygenase-2 inhibitor, etodolac, increase APC mRNA in the colon of rats treated with azoxymethane.

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) have been reported to protect against the development of colon cancer. However, the mechanism(s) by which NSAIDs exert their effects is not clear.

AIMS

The aim of this study was to examine the effects of NSAIDs on mRNA expression of tumour suppressor adenomatous polyposis coli (APC) gene in rat colon mucosa.

METHODS

Starting at six weeks of age, three groups of rats (groups 1, 2, and 3) were treated with azoxymethane (AOM), a colon specific carcinogen, and another three groups (groups 4, 5, and 6) were not given AOM. Groups 2 and 3 were given 10 mg/kg of sulindac or etodolac, respectively, three times weekly during the experiment. Groups 4 and 5 were also given sulindac or etodolac, respectively, in the same manner as in groups 2 and 3. Group 6 (untreated control) was not given any agent (AOM or NSAIDs). At 10 weeks of age, preneoplastic lesions (aberrant crypt foci (ACF)) induced by AOM in the colon were counted, and the level of expression of APC mRNA in the colonic mucosa was estimated by the reverse transcription-competitive polymerase chain reaction method and northern blot analysis.

RESULTS

Mean occurrence of ACF in rats in groups 2 and 3 was reduced to approximately 50% of that in group 1. The level of APC mRNA expression in group 1 (AOM alone) was lower than that in group 6 (untreated control) (p<0.05); however, levels of APC mRNA expression in groups 2, 3, 4, and 5, to which NSAIDs had been administered, were significantly increased compared with levels in groups 1 and 6 (p<0.01).

CONCLUSIONS

Both sulindac and etodolac reduced the occurrence of ACF and induced an increase in APC mRNA in rat colon mucosa.