title: EZH2-induced H3K27me3 is associated with epigenetic repression of the ARHI tumor-suppressor gene in ovarian cancer.
abstract: Epithelial ovarian cancer (EOC) is the second leading cause of death from gynecological malignancies worldwide. Enhancer of zeste homology 2 (EZH2), participating in gene expression silencing by trimethylating histone 3 lysine 27 (H3K27me3), is often up-regulated in EOC. ARHI, an imprinted tumor-suppressor gene, is markedly down-regulated or even undetectable in the majority of EOC. To explore the correlation between EZH2 and ARHI expression in EOC as well as the possible mechanism of EZH2-ARH1 interaction. We used immunohistochemical staining to evaluate the expression of EZH2 and ARHI in EOC and normal ovarian tissue specimens; western blotting, shRNA, and chromatin immunoprecipitation were used to study the expression correlation of EZH2 and ARHI in EOC and normal ovarian epithelial cells and to further explore the mechanism of EZH2 regulation of ARHI expression. Cell viability assay was used to evaluate the influence of these two genes on cell survival. (1) The expression of EZH2 inversely correlated with ARHI expression levels and predicted shorter overall survival in EOC patients; (2) EZH2 promoted repression of ARHI by catalyzing trimethylation on H3K27; (3) ARHI was synergistically silenced by DNA methylation and histone modification; and (4) DZNep, an inhibitor of EZH2, significantly reduced survival rate of EOC cells by restoring ARHI expression. EZH2-″induced H3K27me3 is associated with epigenetic repression of the ARHI tumor-suppressor gene in EOC. Suppression of EZH2 by DZNep, as a way of restoring the expression of ARHI, could be a potential treatment modality to EOC.
authors: Department of Gynecology and Obstetrics, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 100730, China.
authors: Yibing
authors: Y
authors: Fu
authors: Jing
authors: J
authors: Chen
authors: Bo
authors: B
authors: Pang
authors: Chunyan
authors: C
authors: Li
authors: Jing
authors: J
authors: Zhao
authors: Keng
authors: K
authors: Shen
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology; D063646:Carcinogenesis / Q000187:drug effects / Q000235:genetics; D000077216:Carcinoma, Ovarian Epithelial; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D000071221:Enhancer of Zeste Homolog 2 Protein; D063185:Epigenetic Repression / Q000187:drug effects; D005260:Female; D055785:Gene Knockdown Techniques; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000378:metabolism*; D008745:Methylation / Q000187:drug effects; D009375:Neoplasms, Glandular and Epithelial / Q000235:genetics* / Q000473:pathology; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000473:pathology; D063151:Polycomb Repressive Complex 2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D016019:Survival Analysis; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000235:genetics*; D020741:rho GTP-Binding Proteins / Q000172:deficiency / Q000235:genetics*
chemical_list: C117386:DIRAS3 protein, human; D006657:Histones; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; C048460:3-deazaneplanocin; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; D020741:rho GTP-Binding Proteins; D008239:Lysine; D000241:Adenosine