RESUMEN
<p><b>OBJECTIVE</b>To demonstrate the expression of proteolysis induce factor(PIF) in the gastrointestinal(GI) cancer cachexia patients and evaluate its role in cancer cachexia.</p><p><b>METHODS</b>Examination of PIF was performed in urine samples from 28 GI cancer cachexia patients, 13 GI cancer patients without cachexia, and 12 weight loss patients with benign disease. PIF was added to the mice cultured C2C12 muscle cells, then the protein kinase B(Akt) phosphorylation and morphological change were measured.</p><p><b>RESULTS</b>The positive rate of PIF in urine of 28 cancer cachexia patients was 53.6%(15/28). In the other two groups, no positive result was detected. PIF could successfully induce Akt phosphorylation, cell atrophy, metamorphosis, and death. The peak of this phosphorylation could be detected after half an hour of the initiation of PIF at a concentration of 4 nmol/L.</p><p><b>CONCLUSIONS</b>PIF is specifically and highly expressed in GI cancer cachexia patients' urine. PIF can induce cancer cachexia possibly by activating Akt phosphorylation and inducing downstream proteolysis.</p>