title: Effects of diet-induced obesity on colitis-associated colon tumor formation in A/J mice.
abstract: OBJECTIVE
  Studies have indicated that obesity is associated with a higher risk of colorectal cancer. This study was performed to determine the effect of diet-induced obesity on the formation of azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colon tumors and to identify adiposity-related mechanisms.
  
  
  METHODS
  Male A/J mice were placed on either a high-fat diet (HFD; 45% of total calories from fat) or a normal diet (ND; 15% of calories from fat) for 12 weeks. To induce colon tumors, AOM was administered at a dose of 10 mg/kg body weight, followed by two cycles of DSS supply.
  
  
  RESULTS
  Study results indicated that the HFD group had twofold higher numbers of colonic tumors, as compared with the ND group. The HFD group also had significantly increased body weight and epididymal fat weight, which were associated with increases of serum insulin, insulin-like growth factor-1, leptin, epididymal fat pad leptin mRNA and colonic leptin receptor (Ob-R) mRNA. Animals on HFD showed higher expressions of Ob-R, insulin receptor, phosphorylated Akt, phosphorylated extracellular signal-regulated kinases, Bcl-xL and Cyclin D1 proteins in the colon.
  
  
  CONCLUSIONS
  The results suggest that HFD-induced obesity facilitates colon tumor formation, possibly by regulating downstream targets of circulating adiposity-related factors via receptor-mediated signaling of the phosphatidylinositol 3-kinase/Akt pathway.
authors.affiliation: Department of Food and Nutrition, Sookmyung Women's University, Seoul, Korea.
authors.forename: S-Y
authors.initials: SY
authors.lastname: Park
authors.forename: J-S
authors.initials: JS
authors.lastname: Kim
authors.forename: Y-R
authors.initials: YR
authors.lastname: Seo
authors.forename: M-K
authors.initials: MK
authors.lastname: Sung
mesh_terms: D000818:Animals; D001397:Azoxymethane / Q000494:pharmacology*; D015153:Blotting, Western; D002273:Carcinogens / Q000494:pharmacology*; D003092:Colitis / Q000139:chemically induced / Q000150:complications / Q000378:metabolism*; D003106:Colon / Q000378:metabolism* / Q000473:pathology; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D059305:Diet, High-Fat; D004195:Disease Models, Animal; D008297:Male; D051379:Mice; D009765:Obesity / Q000150:complications / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction
chemical_list: D002273:Carcinogens; D001397:Azoxymethane