Expressions and significance of enhancer of zeste homology 2 and signal transducer and activator of transcription 3 in gastric cancer tissues / 中华消化外科杂志

ABSTRACT

Objective To detect the expressions of enhancer of zeste homology 2 (EZH2) and signal transducer and activator of transcription 3 (STAT3) in gastric cancer tissues,and analyze the relationship between their expressions and clinicopathological factors and prognosis of patients.Methods The clinical data of 67 patients with gastric cancer who were admitted to the People's Hospital of Peking University from May 1999 to April 2000 were retrospectively analyzed.Gastric cancer tissues and adjacent normal tissues were harvested and fixed in 4％ formaldehyde,and then to make the tissue chips.The protein expressions of EZH2 and STAT3 were detected by immunohistochemical staining,and the relationship between the expressions of EZH2 and STAT3 and the prognosis of patients was analyzed.The correlation between the protein expressions of EZH2 and STAT3 in the gastric and colorectal tissues and the clinicopathological parameters was analyzed using the paired chi-square test.The survival curve was drawn by Kaplan-Meier method,and the survival rate was analyzed by using the Logrank test.The relationship between the clinicopathological factors and the prognosis of patients was analyzed using the COX proportional hazard model.Results The positive protein expression rates of EZH2 and STAT3 in the gastric cancer tissues were 73.1％ (49/67) and 67.2％ (45/67),which were significantly higher than 32.8％ (22/67) and 37.3％ (25/67) in the adjacent normal tissues (x2=21.839,11.964,P ＜0.05).The protein expression of STAT3 was correlated with the age,TNM staging,lymph node metastatic status (x2=5.475,9.998,5.475,P ＜ 0.05).The protein expression of EZH2 was correlated with TNM staging and lymph node metastatic status (x2=11.573,5.902,P ＜ 0.05).The co-expression rate of EZH2 and STAT3 proteins was 73.1％ (49/67),EZH2 and STAT3 had the common expression trend (r =0.397,P ＜ 0.05).The co-expression rate of EZH2 and STAT3 was increased as the increase of TNM stages,and the co-expression of EZH2 and STAT3 in the gastric cancer tissue was correlated with the TNM stages (x2 =6.997,P ＜ 0.05).The 5-year survival rate of patients with low protein expression of EZH2 was significantly higher than those with high protein expression of EZH2 (x2=7.386,P ＜ 0.05).The 5-year survival rate of patients with low proteins expression of STAT3 was significantly higher than those with high proteins expression of STAT3 (x2=12.253,P ＜ 0.05).The 5-year survival rate of patients with low co-expression of EZH2 and STAT3 protein was significantly higher than those with high co-expression of EZH2 and STAT3 proteins (x2 =8.765,P ＜ 0.05).The results of univariate analysis showed that age,TNM staging,EZH2 and STAT3 expression,lymph node metastasis and distal metastasis were the factors influencing the survival of patients with gastric cancer (RR =2.136,3.452,3.179,8.341,11.773,6.873,P ＜0.05).The results of multivariate analysis showed that TNM staging and STAT3 expression were independent factors influencing the prognosis of patients with gastric cancer (RR =2.453,7.535,P ＜ 0.05).Conclusions There is significant correlation between EZH2 and STAT3 protein expressions in gastric cancer tissues,and co-expression of EZH2 and STAT3 is associated with the TNM staging and the prognosis of the patients with gastric cancer.