Expression of Twist, Slug and Snail in Esophageal Squamous Cell Carcinoma and Their Prognostic Significance

Esophageal cancer is one of the most common types of malignancy worldwide. At present, surgical resection is the main treatment for esophageal cancer, but recurrence and distant metastasis are the main causes of mortality. The transcription factors Twist, Slug and Snail regulate epithelial-mesenchymal transition and thereby participate in tumor invasion and metastasis. The aim of the present study was to investigate the expression of Twist, Slug and Snail in esophageal squamous cell carcinoma (ESCC) and their prognostic significance. The expression of Twist, Slug and Snail in 229 paraffin-embedded ESCC and matched normal mucosal tissues was detected by immunohistochemistry. The expression differences of Twist, Slug and Snail in the ESCC and normal tissues were compared by χ test, and the associations between the three proteins and the clinicopathological parameters of ESCC were analyzed. The expression levels of Twist, Slug and Snail in 29 fresh frozen ESCC and matched normal mucosal tissues were detected by reverse transcription-quantitative PCR. The correlations among Twist, Slug and Snail in ESCC were examined by Pearson's correlation analyses. In addition, single factor and multivariate Cox regression analyses were used to analyze the influence of Twist, Slug and Snail on the prognosis of ESCC. Twist was found to be highly expressed in ESCC. The difference of Slug expression in ESCC was associated with differentiation degree, TNM stage and vascular invasion, but no significant association was observed between Snail expression and any clinicopathological parameters. In ESCC, there were significant differences in protein expression between Twist and Snail, and Slug and Snail. The mRNA expression level of Twist in ESCC was significantly higher than that in normal esophageal mucosa. However, the mRNA expression of Slug in normal esophageal mucosa was higher than that in ESCC, and the mRNA expression levels of Twist and Snail were positively correlated in ESCC. Kaplan-Meier analysis of 229 patients with ESCC revealed that Snail influenced the overall survival, as did the co-expression of Twist and Snail. Nerve invasion was also identified as an independent factor affecting the progression-free survival of ESCC. The results indicate that Twist is highly expressed, Slug may be a tumor suppressor, and Snail is an independent prognostic factor in ESCC. Twist and Snail are positively correlated, and the simultaneous inhibition of Twist and Snail protein expression may be beneficial for prolonging the overall survival of patients with ESCC.