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Abstract

Cachexia is the leading cause of morbidity and mortality in patients with cancer. Mechanisms The effects of cancer cachexia and chemotherapy on small intestinal protein metabolism and the mechanisms regulating recovery are currently not known. Compromises to small intestinal protein metabolism may impair normal digestive and immune functions within the intestine and may negatively impact the whole body. Colon 26 adenocarcinoma induces cancer cachexia in mice, characteristic to the human condition, and this tumour can be cured with 100% efficacy using the experimental alkylating agent, cystemustine. In the present study, both healthy mice and colon 26 adenocarcinoma bearing mice were given either a single i.p. injection of N-(2- Chloroethyl)-N-[2-(methylsulfonyl)ethyl]-N-nitrosourea (cystemustine)(20 mg/kg) or saline 3 d following the onset of cachexia in colon 26 adenocarcinoma bearing mice. The rate of protein synthesis was determined in vivo using the flooding dose method. The possible involvement of proteolysis was assessed through northern blot hybridization of mRNA encoding components of the major proteolytic systems (lysosomal, calcium dependent, ATP-ubiquitin dependent). Villus and crypt morphology was studied through histological analysis. In tumour bearing mice not treated with chemotherapy, cancer cachexia reduced the rate of protein synthesis in the small intestine relative to healthy mice on a fractional (-15 to -20%, P