Expression and Clinicopathologic Significance of Proteolysis-Inducing Factor in Non-Small-Cell Lung Cancer: An Immunohistochemical Analysis

Background: Proteolysis-inducing factor (PIF) is a 24-kD glycoprotein that has been identified in mice and in humans with cancer cachexia. The PIF is a putative mediator of cancer-associated weight loss, which induces atrophy of skeletal muscle. Materials and Methods: In this study, we detected the expression of the PIF in 71 patients with non-small-cell lung cancer (NSCLC) and 10 patients with healthy lung tissues as a control group using the immunohistochemical staining method. In addition, weight loss of patients and serum carcinoembryonic antigen (CEA) and cytokeratin fragment antigen 21-1 (CYFRA 21-1) were measured, and an analysis of overall survival was done. Results: Proteolysis-inducing factor was expressed in only 56.3% (40/71) of lung cancers and not in normal tissue. The positive rate of the PIF expression was significantly higher (P < .01) in patients with weight loss than in those without weight loss. There was no significant relationship (P > .05) between the PIF expression and the histology type, degree of differentiation, or tumor clinical stages in lung cancers. The sensitivity of the PIF was better than that of CEA (P < .05), but similar to that of CYFRA 21-1 in NSCLC. Conclusion: Proteolysis-inducing factor expression was negatively related to the survival of patients with NSCLC in the medium to advanced stages (II-IV). There was a significant correlation between weight loss and survival in the PIF-positive patients.