Elevated expression of ΔNp63 in advanced esophageal squamous cell carcinoma

Abstract

This study aims to explore the expression level of ΔNp63 in esophageal squamous cell carcinoma (ESCC). To investigate the association between ΔNp63 (p40) expression and ESCC biology, we compared the levels of ΔNp63 expression in normal and tumor tissues, with a specific focus on the diagnostic value of ΔNp63 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 ΔNp63 as determined by immunohistochemistry, indicating that ΔNp63 was highly expressed in 75.6% (121/160) of ESCC patients. Clinicopathological analysis of ΔNp63 expression showed that ΔNp63-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 ΔNp63 were 35.6% and 71.7%, respectively. Multivariate analysis revealed that the expression of ΔNp63 was identified as an independent prognostic factor (P = 0.0049) in advanced ESCC. In line with this, ΔNp63α-transduced ESCC cell lines increased tumor growth in a soft agar colony formation assay. We report here for the first time that ΔNp63 expression increases the oncogenic potential of ESCC and is an independent marker for predicting poor outcome in advanced ESCC. Our findings suggest that ΔNp63 could serve as a new diagnostic marker for ESCC and might be a relevant therapeutic target for the treatment of patients with this disease.

Keywords: Carcinogenesis; TP63; esophageal cancer; squamous cell carcinoma; ΔNp63/p40.

Figure 1

Representative immunohistochemical staining of tissue samples from a patient with esophageal squamous cell carcinoma. (a–c) Immunostaining of ΔNp63 shows a nuclear immunostaining pattern with positive ΔNp63 expression: score 0, 0% positive cells (a); 1, 1–25% (b); and 2, >25% (c). (d,e) Immunostaining of p53 with positive p53 expression: score 0 (d) and score 1 (e).

Figure 2

Kaplan–Meier analysis of all cases (n = 160), superficial esophageal squamous cell carcinoma (ESCC) (n = 64), and advanced ESCC (n = 96) in terms of overall survival (a,c,e) and recurrence‐free survival (b,d,f) with respect to ΔNp63 expression. A statistically significant difference in overall survival was observed between advanced ESCC patients with and without tumor expression of ΔNp63 (P = 0.019) (e).

Figure 3

ΔNp63 increases esophageal squamous cell carcinoma tumorigenesis in vitro. (a) Esophageal squamous cell carcinoma cell lines, TE‐1 and TE‐8, were retrovirally infected with LPCX empty vector (Mock) and ΔNp63α. Total RNAs were quantified by real‐time RT‐PCR analysis and the induction level of ΔNp63 was determined by the relative Ct method. (b) Growth of TE‐1 and TE‐8 cells transduced with ΔNp63 were monitored by anchorage‐independent soft agar colony formation assay. Standard deviations are plotted. *P < 0.05.