Muscle UCP-3 mRNA levels are elevated in weight loss associated with gastrointestinal adenocarcinoma in humans

The mitochondrial uncoupling proteins-2 and -3 are putative mediators of thermogenesis and energy expenditure. We measured the mRNA levels of uncoupling proteins-2 and -3 in skeletal muscle from 12 gastrointestinal adenocarcinoma patients, of whom six had stable weight and six had lost 2-18 kg, and from six healthy controls undergoing elective surgery. Uncoupling proteins-3 mRNA levels were significantly higher in the muscle of the cancer patients with weight loss (2.2 +/- 0.47 arbitrary units) compared both with controls (0.39 +/- 0.20) and with cancer patients who had not lost weight (0.47 +/- 0.23; P<0.02). Uncoupling proteins-2 mRNA levels did not differ significantly between groups. Elevations in muscle uncoupling proteins-3 activity may enhance energy expenditure and this in turn could contribute to tissue catabolism.