Prognostic Significance of Overexpression of EZH2 and H3k27me3 Proteins in Gastric Cancer

The enhancer of zeste homolog 2 (EZH2) methyl transferase and histone 3 lysine 27 (H3K27me3) protein canrepress gene transcription, and their aberrant expression has been observed in various human cancers. This studydetermined their expression levels in gastric cancer tissues with reference to clinicopathological features andpatient survival. We collected 117 gastric cancer and corresponding normal tissues for immunohistochemistryanalysis. In gastric cancers, 82/117 (70.1%) were positive for EZH2 and 66/117 (56.4%) for H3K27me3 proteinsin contrast to only 5.41% and 7.25% of normal gastric mucosa specimens, respectively. Kaplan-Meier survivaldata showed the average overall and disease-free survival of EZH2 high expression patients was 25.2 and 20.2months, respectively, shorter than that with EZH2 low expression (40.5 and 35.9 months). The average overallsurvival and disease-free survival of high H3K27me3 expression patients was 23.4 and 17.4 months, shorter thanwithout H3K27me3 expression (37.6 and 34.5 months). The average overall survival and disease-free survival ofpatients with both EZH2 and H3K27me3 expression was 18.8 and 12.9 months, respectively, shorter than thatwith either alone (34.7 and 31.2 months) or with low levels of both (43.9 and 39.9 months). Multivariate Coxregression analysis showed that H3K27me3 and EZH2 expression, tumor size differentiation and clinical stagewere all independent prognostic factors for predicting patient survival. This study demonstrated that detectionof both EZH2 and H3K27me3 proteins can predict poor survival of gastric cancer patients, superior to singleprotein detection. In addition, H3K27me3 and EZH2 protein expression could predict lymph node metastasis.