Elevated expression of Np63 in advanced esophageal squamous cell carcinoma

This study aims to explore the expression level of Np63 in esophageal squamous cell carcinoma (ESCC). To investigate the association between Np63 (p40) expression and ESCC biology, we compared the levels of Np63 expression in normal and tumor tissues, with a specific focus on the diagnostic value of Np63 in ESCC. We analyzed 160 consecutive patients with ESCC who underwent surgical resection without neoadjuvant chemotherapy at Gunma University Hospital (Maebashi, Japan) between September 2000 and January 2010. The clinicopathological characteristics and survival of patients were subclassified based on the expression of Np63 as determined by immunohistochemistry, indicating that Np63 was highly expressed in 75.6% (121/160) of ESCC patients. Clinicopathological analysis of Np63 expression showed that Np63-positive tumors significantly correlated with two important clinical parameters: T factor (P = 0.0316) and venous invasion (P = 0.0195). The 5-year overall survival rates of advanced ESCC patients with positive and negative expression of Np63 were 35.6% and 71.7%, respectively. Multivariate analysis revealed that the expression of Np63 was identified as an independent prognostic factor (P = 0.0049) in advanced ESCC. In line with this, Np63-transduced ESCC cell lines increased tumor growth in a soft agar colony formation assay. We report here for the first time that Np63 expression increases the oncogenic potential of ESCC and is an independent marker for predicting poor outcome in advanced ESCC. Our findings suggest that Np63 could serve as a new diagnostic marker for ESCC and might be a relevant therapeutic target for the treatment of patients with this disease.