Oncotarget

Research Papers:

EZH2-mediated repression of GSK-3β and TP53 promotes Wnt/β-catenin signaling-dependent cell expansion in cervical carcinoma

Qian Chen, Peng-Sheng Zheng _ and Wen-Ting Yang

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Oncotarget. 2016; 7:36115-36129. https://doi.org/10.18632/oncotarget.8741

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Abstract

Qian Chen1, Peng-Sheng Zheng1,2, Wen-Ting Yang1

1Department of Reproductive Medicine, The First Affiliated Hospital of the Medical College, Xi’an Jiaotong University, Xi’an, The People’s Republic of China

2Section of Cancer Stem Cell Research, Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education of the People's Republic of China, Xi'an, The People's Republic of China

Correspondence to:

Peng-Sheng Zheng, email: [email protected]

Wen-Ting Yang, email: [email protected]

Keywords: EZH2, cervical cancer, proliferation, Wnt/β-catenin signaling, GSK3β and TP53

Received: January 03, 2016     Accepted: March 28, 2016     Published: April 15, 2016

ABSTRACT

Enhancer of zeste homolog 2 (EZH2), a catalytic core component of the Polycomb repressive complex 2 (PRC2), stimulates the silencing of target genes through histone H3 lysine 27 trimethylation (H3K27me3). Recent findings have indicated EZH2 is involved in the development and progression of various human cancers. However, the exact mechanism of EZH2 in the promotion of cervical cancer is largely unknown. Here, we show that EZH2 expression gradually increases during the progression of cervical cancer. We identified a significant positive correlation between EZH2 expression and cell proliferation in vitro and tumor formation in vivo by the up-regulation or down-regulation of EZH2 using CRISPR-Cas9-mediated gene editing technology and shRNA in HeLa and SiHa cells. Further investigation indicated that EZH2 protein significantly accelerated the cell cycle transition from the G0/G1 to S phase. TOP/FOP-Flash reporter assay revealed that EZH2 significantly activated Wnt/β-catenin signaling and the target genes of Wnt/β-catenin pathway were up-regulated, including β-catenin, cyclin D1, and c-myc. Moreover, dual-luciferase reporter and chromatin immunoprecipitation (ChIP) assays confirmed that EZH2 inhibited the expression of glycogen synthase kinase-3β (GSK-3β) and TP53 through physically interacting with motifs in the promoters of the GSK-3β and TP53 genes. Additionally, blockage of the Wnt/β-catenin pathway resulted in significant inhibition of cell proliferation, and activation of the Wnt/β-catenin pathway resulted in significant enhancement of cell proliferation, as induced by EZH2. Taken together, our data demonstrate that EZH2 promotes cell proliferation and tumor formation in cervical cancer through activating the Wnt/β-catenin pathway by epigenetic silencing via GSK-3β and TP53.


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