Sulforaphane (SFN) is an isothiocyanate that is present abundantly in widely consumed cruciferous vegetables and has a particularly high content in broccoli and cauliflower. It has been shown to be an effective inhibitor of some carcinogen-induced cancers in rodents. Here, we investigated the chemopreventive efficacy of SFN in the ApcMin/+ mouse model. ApcMin/+ mice were fed with diet supplemented with two different dose levels of SFN (300 and 600 p.p.m.) for 3 weeks. Our results clearly demonstrated that ApcMin/+ mice fed with SFN-supplemented diet developed significantly less and smaller polyps with higher apoptotic and lower proliferative indices in their small intestine, in a SFN dose-dependent manner. In addition, immunohistochemical (IHC) staining of the adenomas indicated that SFN significantly suppressed the expression of phosphorylated c-Jun N-terminal kinase (p-JNK), phosphorylated extracellular signal-regulated kinases (p-ERK) and phosphorylated-Akt (p-Akt), which were found to be highly expressed in the adenomas of ApcMin/+ mice. In contrast, expression of two important biomarkers of the Wnt signaling pathway, β-catenin and cyclin-D1 was unaffected by SFN treatment. Measurement of SFN and its metabolite SFN-GSH in the small intestine using LC-MS indicates that the concentrations between 3 and 30 nmol/g are required to prevent, or retard adenoma formation in the gastrointestinal tract of ApcMin/+ mice.
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We thank the members of the laboratory of Dr Kong as well as members of the Center for Prevention Research at Ernest Mario School of Pharmacy, Rutgers University for many insightful discussions. This work was supported by NIH grant RO1 CA073674.