Claudin upregulation in ovarian carcinoma effusions is associated with poor survival

Claudins are tight junction proteins that are highly expressed in ovarian carcinoma (OC). The objective of this study was to analyze the anatomic site-related expression and clinical role of claudins in OC. Effusions (n = 218), corresponding primary tumors (n = 81), and solid metastases (n = 164) (total = 463 tumors) were immunostained for claudin-1, claudin-3, claudin-4, and claudin-7. Results were analyzed for association with anatomic site, clinicopathologic parameters, and survival. All 4 claudins were expressed in >85% of tumors at all anatomic sites. However, staining extent of all except claudin-4 was significantly higher in effusions compared with both primary carcinomas and solid metastases (P < .001). In univariate survival analysis of the entire cohort, higher claudin-3 (P = .038) and claudin-7 (P = .035) expression in effusions correlated with shorter overall survival (OS), with similar results for claudin-7 in analysis of progression-free survival (P = .026). In separate analysis for patients with prechemotherapy effusions, higher claudin-7 expression correlated with shorter OS (P = .045). For patients with postchemotherapy effusions, higher claudin-1 (P = .018) and claudin-3 (P = .009) expression correlated with shorter OS. In multivariate survival analysis of the entire cohort, claudin-7 expression was an independent predictor of poor progression-free survival (P = .017). Claudin-3 independently predicted poor OS for patients with postchemotherapy effusions (P = .012). With the exception of claudin-4, claudins are upregulated in OC effusions compared with solid tumors, in agreement with our previous data for cadherins and integrins in this cancer type, suggesting a prosurvival role for these surface molecules. Claudin-3 and claudin-7 expression in effusions independently predicts poor survival in OC.