Ezrin protein overexpression predicts the poor prognosis of pancreatic ductal adenocarcinomas

Ezrin, a member of the ezrin/radixin/moesin (ERM) protein family, plays an important role in tumor metastasis. Accumulating studies demonstrated that a high expression level of human ezrin has been correlated with numerous human malignancies. This study was aimed to explore the clinicopathological significance of ezrin protein expression in pancreatic ductal adenocarcinomas (PDAC), and to further identify its role as a potential biomarker and therapeutic target of PDAC. Immunohistochemical (IHC) staining of ezrin protein was performed on 106 PDAC tissue samples and 37 adjacent and 21 normal pancreatic tissue samples. Additionally, localization of ezrin protein in Panc-1 PDAC cell line was observed using immunofluorescence (IF) staining. The correlation between ezrin overexpression and the clinicopathological features of PDAC was evaluated using Chi-square test, and differences in survival curves were analyzed using log-rank tests. In results, ezrin protein is widely distributed in the cytoplasm and membrane of PDAC cells by IHC and IF staining, but some cases showed a cell membrane staining pattern. The positive rate of ezrin protein expression was 82.1% (87/106) in PDAC, which was significantly higher than it in either adjacent pancreatic tissues (37.8%, 14/37) or normal pancreatic tissues (19.0%, 4/21). Overexpression of ezrin was closely related with larger tumor size, positive lymph node metastasis and advanced clinical stage. However, it was not correlated with patient age, gender, differentiation, Ki-67 expression index, and pancreas calcification point. Survival analysis showed that patients with ezrin high expression level had significantly lower overall survival rate than that with ezrin low expression level. Importantly, further analysis using a Cox proportional hazard regression model revealed that high ezrin expression emerged as a significant independent hazard factor for overall survival rates of patients with PDAC along with lymph node metastasis and TNM stage. In conclusion, ezrin protein played an important role in the progression of PDAC, and the overexpression of ezrin protein might be a useful prognostic marker of PDAC.