Interleukin-6 and cachexia inApcMin/+mice

Abstract

The ApcMin/+mouse has a mutation in the Apc tumor suppressor gene and develops intestinal polyps, beginning at 4 wk of age. This mouse develops cachexia by 6 mo, characterized by significant loss of muscle and fat tissue. The purpose of the present study was to determine the role of circulating interleukin-6 (IL-6) and the polyp burden for the development of cachexia in ApcMin/+mice. At 26 wk of age, mice exhibiting severe cachectic symptoms had a 61% decrease in gastrocnemius muscle weight, complete loss of epididymal fat, a 10-fold increase in circulating IL-6 levels, and an 89% increase in intestinal polyps compared with mildly cachectic animals. ApcMin/+/IL-6−/−mice did not lose gastrocnemius muscle mass or epididymal fat pad mass while overall polyp number decreased by 32% compared with ApcMin/+mice. Plasmid-based IL-6 overexpression in ApcMin/+/IL-6−/−mice led to a decrease in gastrocnemius muscle mass and epididymal fat pad mass and increased intestinal polyp burden. IL-6 overexpression did not induce cachexia in non-tumor-bearing mice. These data demonstrate that IL-6 is necessary for the onset of adipose and skeletal muscle wasting in the ApcMin/+mouse and that circulating IL-6 can regulate ApcMin/+mouse tumor burden.