Clusterin immunoexpression and its clinical significance in patients with non-small cell lung cancer

Clusterin is an enigmatic glycoprotein with a nearly ubiquitous tissue distribution. It plays important roles in various pathophysiological processes, including tissue remodeling, reproduction, lipid transport, complement regulation, and apoptosis. Clusterin appears to have two main isoforms that result from alternative splicing. The secreted and nuclear forms of clusterin have been reported to play different roles in human malignancies. The purpose of this study was to examine clusterin immunoexpression and its clinical significance in a group of Chinese patients with non-small cell lung cancer (NSCLC). Tissue samples from the primary tumors of 121 patients with completely resected NSCLC were obtained. Clusterin protein expression was evaluated by immunohistochemical staining with an antibody against all clusterin isoforms. Staining patterns were observed and graded based on intensity and density and were correlated with clinical and pathological data. Both cytoplasmic and nuclear clusterin immunostaining patterns were observed. Clusterin staining was observed only in the cytoplasm in 70 patients (57.9%), only in the nucleus in 27 patients (22.3%), and in both the cytoplasm and nucleus in 16 patients (13.2%). A significant association was observed between positive cytoplasmic clusterin expression and histologic type as indicated by adenocarcinomas that were more likely to have clusterin staining only in the cytoplasm. Clusterin immunostaining was neither associated with recurrence-free survival (RFS) nor overall survival of patients by univariate or multivariate analysis. For patients undergoing chemotherapy, those with only cytoplasmic clusterin staining had worse survival than other patients. In conclusion, both cytoplasmic and nuclear immunostaining patterns of clusterin were detected in the tumors of patients with NSCLC. Adenocarcinomas were more likely to have only cytoplasmic staining. The immunoexpression of clusterin was not associated with prognosis, and cytoplasm-only immunostaining of clusterin was inversely correlated with chemosensitivity in this group of patients.