Abstract
BackgroundCystatin SN is a secreted protein and a cysteine proteinase inhibitor. It has been considered to be a tumor marker for gastrointestinal tract cancer in several functional researches. However, the clinicopathological and prognostic significance of Cystatin SN expression in esophageal squamous cell carcinoma (ESCC) has not been elucidated.MethodsIn our study, the expression of Cystatin SN was detected in 209 surgically resected ESCC tissues and 170 peritumoral normal esophageal mucosae by immunohistochemistry. The prognostic significance of Cystatin SN expression was analysed with Kaplan-Meier plots and the Cox proportional hazards regression models.ResultsThe results showed that the immunostaining of Cystatin SN in ESCC tissues was less intense than that in the normal control tissue (P < 0.001). Compared with patients with low tumoral Cystatin SN expression, ESCC patients with tumors high-expression Cystatin SN exhibited increased disease-free survival (DFS) and overall survival (OS) (P < 0.001 and P < 0.001, respectively). Furthermore, the expression level of Cystatin SN could further stratify the ESCC patients by survival (DFS and OS) in the stage II subgroup (P < 0.001 and P < 0.001, respectively). Multivariate analyses showed that Cystatin SN expression, N status and differentiation were independent and significant predictors of survival.ConclusionsWe concluded that ESCC patients whose tumors express high levels of Cystatin SN have favourable survival compared with those patients with low Cystatin SN expression. Tumoral Cystatin SN expression may be an independent predictor of survival for patients with resectable ESCCs.
Highlights
Cystatin SN is a secreted protein and a cysteine proteinase inhibitor
Using the criteria described above, strong staining (3+) of Cystatin SN was detected in all of normal squamous epithelial cells, whereas various staining patterns were obtained in the esophageal squamous cell carcinoma (ESCC) tissues
There was no significant associations between the Cystatin SN expression of the ESCCs and age, gender, tumor location, differentiation, T status, N status, and pathological stage in the Chi-squared test (P > 0.05, Table 1)
Summary
It has been considered to be a tumor marker for gastrointestinal tract cancer in several functional researches. The clinicopathological and prognostic significance of Cystatin SN expression in esophageal squamous cell carcinoma (ESCC) has not been elucidated. China accounts for approximately 53.6% of new cases and 51.7% of EC-related worldwide [2]. In China, Cysteine proteases are involved in tissue remodeling during development, and they induce the migration of cancer cells [5,6]. The expression, function and location of many proteases are associated with tumor progression [5,7,8]. Recent evidence suggests that lysosomal cysteine proteases play an important role in ESCC growth, invasion and metastasis [7,8]
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