Chemopreventive agents-induced regression of azoxymethane-induced aberrant crypt foci with the recovery of hexosaminidase activity.

colon polyps in familial adenomatosis polyposis (FAP) patients Department of Pathology, Center for Environmental Medicine, Medical (14–17). Hence, in both clinical and laboratory investigations, College of Ohio, 3000 Arlington Avenue, Toledo, OH 43614, USA NSAIDs appear to prevent the progression of precancerous 1To whom correspondence should be addressed lesions in the colon. Regression of precancerous lesions has been used in experiIn the AOM-induced colon cancer model, one of the earliest mental and clinical studies to indicate chemoprevention in the recognizable precancerous lesions is the appearance of aberrant colon, including the regression induced by piroxicam of the crypt foci (ACF) (18–22). These foci are putative precancerous putative precancerous lesion, aberrant crypt foci (ACF). ACF lesions that indicate at least the initiation of the carcinogenic lack hexosaminidase activity, while normal crypts possess the process and predict an increased likelihood of cancer developactivity. We evaluated the ability of four potential chemoprevment (11). ACF are easily distinguished in methylene blueentive agents to induce regression of ACF and to induce stained whole mounts of rat colon by the procedure developed hexosaminidase activity in them. Male F-344 rats were i.p. by Bird (18). In our previous studies, piroxicam was demonadministered 18 mg/kg body wt AOM at week 7 and again at strated not only to prevent AOM-induced ACF when adminisweek 8 of age. Five weeks after the first dose of AOM, tered prior to the carcinogen, but also to induce regression of curcumin (12 g/kg diet), ferulic acid (FA, 1 g/kg diet), or ACF when administered after the carcinogen, both of which difluoromethylornithine (DFMO, 2 g/kg diet) were added to were associated with the prevention of colon tumors (13,22). the diet. Also, at that time, other rats started to receive 0.3 g/ Pretlow et al. have reported that AOM-induced ACF lacked kg body weight perillyl alcohol (PA) by gavage in corn oil or hexosaminidase activity in contrast to normal crypts that remained on the control diet. Rats were killed at 0, 10 and 28 contained activity (20). ACF do not differentiate normally; for days after the start of administering the chemopreventive example, they have a greatly reduced number of goblet cells. agents. After 28 days of exposure, curcumin induced the The association of a decrease in hexosaminidase activity regression of ACF, DFMO and PA prevented the occurrence with ACF, would suggest that it might be a biomarker for of new ACF, and FA did not prevent ACF nor induce their differentiation of colonic crypts. In this study, we evaluated regression. After 10 days of exposure, the order for the ability the ability of four potential chemopreventive agents to induce to induce hexosaminidase activity in ACF was curcumin . regression of ACF in rat colons and determined whether PA . DFMO . FA, which corresponded to the ability of recovery of hexosaminidase activity was associated with these agents to induce regression and/or prevention of ACF. regression of ACF. The four agents were curcumin, ferulic By 28 days of exposure, the percentage of foci that regained acid (FA), difluoromethylornithine (DFMO), and perillyl alcohexosaminidase activity was much less than at 10 days. The hol (PA) which were chosen to represent a naturally occurring results demonstrated that another NSAID, curcumin, can induce NSAID, an antioxidant, an ornithine decarboxylase inhibitor, the regression of ACF and that the reappearance of hexosaminiand an inhibitor of farnesyl transferase, respectively. dase activity might be a biomarker for the ability to induce Male F-344 rats (certified viral antibody-free) were obtained the differentiation and regression of ACF. at 5 weeks of age from Charles River Laboratories (Raleigh, Colorectal cancer accounts for ~20% of all cancer deaths NC). The rats were maintained in an AAALAC accredited in the US and is the second leading cause of cancer death in facility that was in accordance with the Animal Welfare Act men and the third leading cause in women (1). One of (Public Law 89-544, 94-279) and NIH Publication no. 86-23 the strategies to decrease its toll is the development of revised 1985 entitled Guide for the Care and Use of Laboratory chemopreventive agents. Aspirin, piroxicam, sulindac and Animals. Solid-bottom polycarbonate cages with stainless steel other non-steroidal anti-inflammatory drugs (NSAIDs*) are wire-bar lids and Bed-o-Cob bedding (Andersons, Toledo, OH) undergoing laboratory (2–7) and clinical investigation (8–10) were used to house two rats per cage. The light cycle consisted for use as chemopreventive agents of colon cancer. One of the of 12 h each of light and dark. The animal rooms were models used to evaluate agents for chemoprevention in the maintained at 64–76°F and 55 6 15% relative humidity. The colon is the azoxymethane (AOM)-induced colon cancer model rats were fed AIN-76A diet (Bioserve, Frenchtown, NJ) in rats (11). Using this model, NSAIDs including aspirin, consisting of 20% casein, 0.3% DL-methionine, 52% corn curcumin, piroxicam, and sulindac have been shown to prevent