High expression of Capn4 is associated with metastasis and poor prognosis in esophageal squamous cell carcinoma

Calpain small subunit1 (Capn4) is present in various cancer types and is implicated in tumor metastasis. However, the role of Capn4 in esophageal squamous cell cancer (ESCC) has not been elucidated. In this study, immunohistochemistry was conducted to detect Capn4 expression and localization in 155 ESCC tissues and in 35 adjacent normal esophageal mucosal tissues. Following knockdown of Capn4 in esophageal cancer cells using RNA interference, we detected the migration and invasion ability of cells. The role of Capn4 on prognosis was evaluated using univariate and multivariate analysis in 155 ESCC patients. The immunohistochemistry results showed that Capn4 was highly expressed in ESCC tissues compared with normal peritumor esophageal tissues, and Capn4 overexpression was significantly related to tumor size (P = 0.027), tumor invasion depth (P = 0.019), and lymph node metastasis (P = 0.011). Knockdown of Capn4 drastically reduced migration and invasion of ESCC cells. Based on the results of the univariate analysis, patients with higher Capn4 had a poor prognosis. Through multivariate analysis, we found that Capn4 was an independent prognostic factor for overall survival in ESCC. These findings suggest that Capn4 overexpression contributes to the aggressive progression of ESCC and functions as a prognostic marker for patients with ESCC.