Expression And Clinical Significance Of PDCD5 And Smac In Esophageal Squamous Cell Carcinoma

Background:China has a relatively high incidence of esophageal neoplasm and has the highest esophageal neoplasm mortality rate. Esophageal neoplasm has been a serious threat to our people's health. Programmed cell death 5 (PDCD5) is a novel apoptosis-promoting protein that accelerates apoptosis in different cell types in response to various stimuli, and has been shown to be down-regulated in many cancer tissues. PDCD5 expression may play an important role in the pathogenesis of human cancers. Although the decreased expression of PDCD5 has been recently found in a few types of human tumors, the status and significance of PDCD5 in esophageal squamous cell carcinoma (ESCC) has not been evaluated. Smac is a dimeric protein important in the control of apoptosis by removing the inhibitory activity of inhibitor of apoptosis proteins (IAPs). Therefore, the study of the expression of PDCD5 and Smac expression in esophageal tissue can offer biological basis for the diagnosis of esophageal neoplasm.Objective:This study was to explore the expressions of PDCD5 and Smac and their clinical significance in esophageal squamous cell carcinoma. Methods:58 patients with 36 males and 22 females who had undergone ESCC in department of Pathology, the First Affiliated Hospital of Zhengzhou university from October 2008 to August 2009, were enrolled in this study. ESCC had been confirmed by histopathological diagnosis in all tissue samples. All patients were not received preoperative chemotherapy,radiotherapy and immunotherapy before operation. The average age was 60.5years.10 well-differentiated,40 moderately and 35 poorly differentiated; TNM staging:Ⅰ-Ⅱperiod of 30 cases, III-IV period of 28 cases; 20 cases with lymph node metastasis and 38 cases without lymph node metastasis. In addition 23 normal esophagus tissues were used as the control. The expression of PDCD5 and Smac in 58 specimens of ESCC and 23 specimens of normal esophageal tissues adjacent to cancer were detected by immunohistochemistry, the correction of PDCD5 expression to Smac expression, and their corrections to the clinicophathologic features of ESCC were analyzed by SPSS13.0. Chi-squared test and Spearman's rank correlation were performed to compare difference bewteen groups and relativity analysis respectively. The significant difference was considered when the P value was less than 0.05.Results:PDCD5 expresses mainly in the nucleolus. The positive rate of PDCD5 was significantly lower in ESCC than that in normal esophageal tissues adjacent to cancer (41.4% vs.78.3%, P<0.05),and closely related to TNM stage and lymph node metastasis (P<0.05)Smac expresses mainly in the cytoplasm. The positive rate of Smac was significantly lower in ESCC than that in normal esophageal tissues adjacent to cancer (32.8% vs.73.9%, P<0.05), and closely related to differentiation grade and lymph node metastasis (P<0.05)PDCD5 expression was positively correlated to Smac expression (r=0.416, P< 0.05).Conclusion: 1 The expression of PDCD5 in ESCC tissues is down regulation. The expression of PDCD5 is closely related to TNM stage and lymphnode metastasis, it may play a important role in the occurrence and development of ESCC.2 The expression of Smac in ESCC tissues is down regulation. The expression of Smac is closely related to differentiation grade and lymphnode metastasis, it may play a important role in the occurrence and development of ESCC.3 The expressions of PDCD5 and Smac in ESCC tissues are significantly positive correlated. It suggests that the down-regulation of PDCD5 and Smac expression may correlate to the occurrence and development of esophageal squamous cell carcinoma, which could provide a reference for the diagnosis of esophageal squamous cell carcinoma.