High fat diet-induced obesity increases the formation of colon polyps induced by azoxymethane in mice.

BACKGROUND Obesity has been found to be associated with colon cancer. However, the mechanism of this relationship is unclear and thus a good animal model is required. Our previous research showed that some mice developed diet-induced obesity (DIO) whilst others were diet-resistant (DR) when fed a high-fat diet. METHODS In the present study, we have tested the effects of a high-fat diet on the formation of colon polyps induced by azoxymethane (AOM) in both DIO and DR mice. RESULTS We found that the DIO mice have developed 2.5 times of polyps compared to the DR mice (P<0.05) and 3.4 times of polyps compared to the low fat fed mice (P<0.05). Although the DR mice tended to have more polyps than the low-fat diet fed mice, this was not statistically significant. The DIO mice could have an increased polyp formation due to obesity-related cancer risk factors and different gene expression from DR mice. CONCLUSIONS DIO mice could be used as an appropriate model for studying obesity-associated colon cancer; however DR mice are not suitable because they don't show any significant weight gains to indicate obesity.