Expression and significance of STAT3 and its phosphorylation in esophageal squamous cell carcinoma tissue

Abstract

Objective By testing the expression of signal transducer and activator of transcription 3 (STAT3) in esophageal squamous cell carcinoma (ESCC) tissue at mRNA, protein and protein phosphorylation levels, to study the function of STAT3 in the occurrence, development, invasion and metastasis of ESCC. Methods By using adjacent normal esophageal tissue as control, the expression of STAT3 mRNA,STAT3 and phosphorylated STAT3 (pSTAT3) in 43 ESCC samples was detected to reveal the correlation with clinicopathological rarameters. Results In the 43 tested samples, ( 1 ) Remarkably higher relative expression intensity of STAT3 at mRNA was found in ESCC tissue ( 1.43 ±0. 59), than in normal esophageal tissue (0. 98 ± 0.47, P ＜ 0. 05 ) ; ( 2 ) STAT3 and pSTAT3 expression in ESCC (2. 16 ± 0. 39, 1.40 ±0. 15) was also significantly higher than in normal tissue ( 1.87 ± 0. 29, 1.25 ± 0. 13, P ＜ 0.05 ) ; ( 3 )Statistical differences were found in different differentiation degrees of tumor for the expression of STAT3 mRNA, STAT3 and pSTAT3 in ESCC. The lower differentiation degree was, the higher the expression (P ＜0. 05). The expression was negatively correlated with differentiation degree of tumor (-1 ＜ r ＜-0. 301 ,P＜ 0. 05 ), while it had a positive relationship with TNM staging and lymph node metastasis (0. 301 ＜r ＜ 1 ,P ＜0. 05). In TNM staging, higher expression was found in stage Ⅲ than in both stage Ⅰ and stage Ⅱ (P ＜ 0. 05 ), and the expression in the group with lymph node metastasis was higher than that in the group without lymph node metastasis ( P ＜ 0. 05 ). No obvious connection was found with the age,gender, family history and smoking history of patients (P ＞ 0. 05 ). Conclusion High expression of STAT3 mRNA, STAT3 and pSTAT3 in ESCC tissue was caused by the aberrant activation of STAT phosphorylation, which was closely related with the differentiation, invasion and metastasis of ESCC. Key words: Esophageal squamous cell carcinoma; STAT3