Inhibitory Effects of Low-Dose Aloe-Emodin on the Development of Colorectal Tumors in Min Mice

Aloe-emodin (AE), a natural anthraquinone compound, has been reported to exhibit anticancer activityin various cancer cell lines and anti-inflammatory effects in murine macrophages. In the present study, weinvestigated the cancer chemopreventive effects of AE in an Apc-deficient Min mouse model. In the firstexperiment, male Min mice were fed a basal diet or diets containing 5 ppm AE and 10 ppm AE for 12 weeks.The dietary administration of 5 ppm AE significantly reduced the number of colorectal tumors. In a secondexperiment, we investigated the effects of AE on colitis-related colon carcinogenesis in Min mouse treated withdextran sodium sulfate (DSS). Female Min mice were administered 1% DSS in their drinking water for 7 days.AE was given to mice in their diet at a dose of 5 or 50 ppm for 5 weeks. Feeding with AE significantly reducedthe number of colorectal tumors. When proliferation of cells in normal-appearing colonic mucosa was assessedby monoclonal anti-rat Ki-67 antibody (MIB-5) immunohistochemistry in experiments 1 and 2, the AE treatmentsignificantly decreased the mean MIB-5-labeling index. These results suggest that the dietary administration oflow-dose AE may have chemopreventive effects against development of colorectal tumors in Min mice, possiblyin part by reducing cell proliferation in colorectal mucosa.