Abstract
Enhancer of zeste homologue 2 (EZH2) is a potential independent mechanism for epigenetic silencing of tumor suppressor genes in cancer. We conducted an electronic search on PubMed, EMBASE, Web of Science, and Cochrane library to perform this up-to-date meta-analysis. Fifty-one studies with a total of 9444 patients were included. The prevalence of high EZH2 expression was 0.54 (95% CI: 0.47-0.61). High EZH2 expression was significantly associated with poorer prognosis [overall survival: HR 1.54 (95% CI: 1.30-1.78), P < 0.000; disease free survival: HR 1.35 (95% CI: 1.00-1.71), P < 0.000]. In breast cancer, high EZH2 expression correlated with histological types [OR: 1.53 (95CI: 1.13-2.06); P < 0.006], histological grade [OR: 1.62 (95CI: 1.35-1.95); P < 0.000], estrogen receptor (ER) negativity [OR: 2.05 (95CI: 1.67-2.52); P < 0.000], progesterone receptor (PgR) negativity [OR: 1.42 (95CI: 1.03-1.96); P = 0.034], HER-2 positivity [OR: 1.35 (95CI: 1.08-1.69); P = 0.009], and high p53 expression [OR: 1.66 (95CI: 1.07-2.59); P = 0.024]. These results suggest that high EZH2 expression may be a promising prognostic factor to different cancers. High EZH2 expression tends to correlate with pathological types, histological grade, ER negativity, PgR negativity, HER-2 positivity and p53 high expression in breast cancer.
Highlights
Enhancer of zeste homologue 2 (EZH2) is a catalytic subunit of the polycomb repressive complex 2 (PRC2), which represses gene expression by methylating lysine 27 of histone 3 (H3K27)[1]
Sixteen of 51 studies were in breast cancer, 10 studies were in lung cancer, 7 studies were in colorectal cancer (CRC) and other 21 studies were about digestive, gynecological and urinary cancers
The results indicated that EZH2 highly expressed in 18 kinds of human cancers and the incidence of high EZH2 expression was 0.54
Summary
Enhancer of zeste homologue 2 (EZH2) is a catalytic subunit of the polycomb repressive complex 2 (PRC2), which represses gene expression by methylating lysine 27 of histone 3 (H3K27)[1]. Previous studies have showed that high expression of EZH2 was correlated with aggressiveness, metastasis, and poor prognosis in breast, prostate, bladder and renal cell cancer[11,12,13]. There have been already a metaanalysis on this issue, several important articles are not included in that paper and the subgroup analysis give little useful information[22] We performed this up-todate systematic review with meta-analysis on the influence of high EZH2 expression on the outcomes of different cancers, as well as the incidence of high EZH2 expression, www.impactjournals.com/oncotarget and to provide an overview of the current status of high EZH2 expression in tumor progression and therapy
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