Loss of adiponectin promotes intestinal carcinogenesis in min and wild-type mice

Abstract

Background & Aims: Metabolic syndrome- and obesity-associated cancers, including colon cancer, are common in Western countries. Visceral fat accumulation and decreased levels of plasma adiponectin (APN) have been associated with development of human colorectal adenoma. We investigated the function of APN in intestinal carcinogenesis. Methods: APN+/+, APN+/-, or APN-/- mice (C57BL/6J) were given injections of azoxymethane (AOM), which led to development of intestinal tumors; these strains of mice were also crossed with Min mice to assess polyp formation. Adipocytokine levels and phosphorylation/activation of AMP-activated protein kinase (AMPK) were evaluated to investigate the mechanisms of APN in tumor growth. Results: The total number of polyps in the intestines of male APN +/- Min and APN-/-Min mice increased 2.4- and 3.2-fold, respectively, by the age of 9 weeks and 3.2- and 3.4-fold, respectively, by 12 weeks, compared with those of APN+/+Min mice. Similar results were obtained from female mice. AOM induced colon tumor formation in 40% of APN +/+, 50% of APN+/-, and 71% of APN-/- (P < .05) mice, respectively; mean values for tumor multiplicity of each genotype were 0.5, 0.6, and 1.1 (P