High‐fat diet induced obesity accelerates colon tumor formation in AJ and ICR mice

Abstract

Recent studies have indicated that the risk of colorectal cancer is associated with overweight and obesity. The objective of this study was to determine the effect of high fat diet induced obesity on the incidence of AOM/DSS‐induced colon carcinogenesis and to elucidate possible mechanisms. Strain‐specific responses were studied using A/J and ICR mice. Study results indicated the tumor numbers in animals fed high fat diet were significantly higher than those of the animals on low‐fat diet. The concentrations of adipose tissue related serum factors including leptin, insulin and IGF‐1 were elevated in obese animals indicating these are one of the possible signals to facilitate colon tumor formation. The expressions of leptin mRNA in adipose tissue and leptin receptor(ObR) mRNA in colon tissue were significantly higher in obese mice compared to those in lean mice only in AJ stain. The protein expressions of ObR, IR, p‐Akt, p‐ERK, Bcl‐xl and cyclin D1 were higher in obese animals than those in lean animals for both strains. These results imply adipose tissue related hormonal factors contribute to colon tumor growth. Strain‐specific responses are also suggested. This study was supported by the SRC program of the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (2009‐0063409 and R01‐2008‐000‐20708‐0).Grant Funding Source: Nutrition(ASN)