Abstract
Patients with esophageal squamous cell carcinoma (ESCC) have a poor prognosis. Identification of biomarkers to accurately predict the risk of recurrence and survival following curative esophageal resection is required to improve patient outcomes. The copine 5 (CPNE5) gene encodes a calcium‑dependent lipid‑binding intracellular protein. Copine proteins interact with diverse target proteins that are components of pathways that aberrantly regulate the phenotypes of malignant cells. However, limited information is available on the role of CPNE5 in cancer. The present study investigated whether CPNE5 may serve as a predictive marker of the prognosis of patients with ESCC following curative resection. CPNE5 mRNA expression levels and the methylation status of the CPNE5 promotor region were measured in 11 ESCC cell lines. CPNE5 mRNA expression levels in 106 pairs of surgically resected specimens were measured, and their associations with clinicopathological characteristics were analyzed. The CPNE5 mRNA expression levels in 9 ESCC cell lines were decreased compared with those of the non-tumorigenic esophageal mucosa cell line Het‑1A. Bisulfite sequencing detected the methylation of the CPNE5 promotor region in all cell lines tested, including Het‑1A. Furthermore, analysis of tissues revealed that CPNE5 mRNA expression was significantly lower in ESCC cells compared with cognate non-cancerous adjacent mucosal cells. Kaplan‑Meier analysis revealed that patients with low CPNE5 expression experienced significantly shorter overall survival. Multivariable analysis identified low CPNE5 expression to be an independent prognostic factor of OS. Analysis of recurrence patterns revealed that significantly more patients with local recurrence expressed lower levels of CPNE5 mRNA. These findings indicated that CPNE5 expression in ESCC tissues may serve as an informative biomarker for predicting ESCC recurrence, particularly in patients with local recurrence, and may help to ensure that patients receive optimal treatment and follow‑up.