Modifying effects of dietary exposure of S-methyl
methane thiosulfonate (
MMTS) isolated from cauliflower Brassica oleracea L. var. botrytis on rat colon
carcinogenesis induced by
azoxymethane (AOM) and on the expression of cell proliferation
biomarkers were investigated in two experiments. In experiment 1, male F344 rats were given three s.c.
injections of AOM (15 mg/kg
body weight) and fed 100 ppm
MMTS for 5 weeks, starting 1 week before the first dose of AOM. The frequency of colonic
aberrant crypt foci was determined at 5 weeks after the start. Feeding of 100 ppm
MMTS for 5 weeks significantly decreased the number of
aberrant crypt foci/colon. Colonic mucosal
ornithine decarboxylase activity and the number of
silver-stained nucleolar organizer regions per nucleus in colonic epithelium were significantly decreased by
MMTS treatment compared with those of AOM alone. In experiment 2, effects of dietary feeding of
MMTS at two doses (20 and 100 ppm) during the postinitiation phase on intestinal
tumorigenesis initiated with AOM were investigated by using a long-term experiments in male F344 rats. Incidence of
intestinal neoplasms of rats fed
MMTS-containing diets after AOM exposure were reduced in a dose-dependent manner. Feeding of
MMTS during the postinitiation phase decreased the number of
aberrant crypt foci/colon, colonic
ornithine decarboxylase activity, 5-bromodeoxyuridine-labeling index in colonic epithelium, and
polyamine level in blood compared with those of AOM alone. These results suggest that
MMTS might be a possible chemopreventive agent for intestinal
neoplasia.