PURPOSE: PURPOSE:The effect of pravastatin, an inhibitor of ras p21 isoprenylation, on the gross type of colon tumors induced by azoxymethane was investigated in Wistar rats.
METHODS: METHODS:Rats received ten weekly subcutaneous injections of 7.4 mg/kg body weight of azoxymethane and intraperitoneal injections of 10 or 20 mg/kg body weight of pravastatin every other day until the end of the experiment at Week 45.
RESULTS: RESULTS:Administration of pravastatin at both dosages had no significant effect on the incidence of colon tumors but significantly increased the incidence of rats with adenomas only. In contrast to the elevated adenomas in control rats, flat adenomas were significantly more prevalent in rats given pravastatin. Pravastatin at both doses significantly decreased the labeling index, but not the apoptotic index, of elevated adenomas, whereas it significantly decreased the labeling index but increased the apoptotic index of flat adenomas. Administration of pravastatin at both dosages also significantly decreased the amounts of membrane-associated ras p21 in colon tumors.
CONCLUSIONS: CONCLUSIONS:These findings suggest that the ras oncogene may be closely related to the development of adenocarcinomas from adenomas and the development of elevated or polypoid tumors of the colon.
Supported in part by a Grant-in-Aid for the Second-Term Comprehensive 10-Year Strategy for Cancer Control from the Ministry of Health and Welfare, Japan.
© The ASCRS 2000