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

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.

LncRNA BDNF‐AS suppresses colorectal cancer cell proliferation and migration by epigenetically repressing GSK‐3β expression

“…Zhang et al found that lncRNA‐ANCR accelerated cell proliferation, migration, and invasion of osteosarcoma (OS) cells by downregulating p21 and p27 via interacting with EZH2 . It is noteworthy that EZH2 has been reported to downregulate the level of GSK‐3β gene expression through H3K27me3 in the GSK‐3β promoter . In our study, we found a significantly higher level of GSK‐3β levels in CRC tissues compared with adjacent normal tissues and cell lines, which was consistent with the previous studies .…”

“…20 It is noteworthy that EZH2 has been reported to downregulate the level of GSK-3β gene expression through H3K27me3 in the GSK-3β promoter. 11 In our study, we found a significantly higher level of GSK-3β levels in CRC tissues compared with adjacent normal tissues and cell lines, which was consistent with the previous studies. 5,21,22 In addition, we observed that GSK-3β mRNA and protein levels were markedly decreased due to lncRNA BDNF-AS overexpression in vitro.…”

“…However, the functions and underlying mechanism of lncRNA BDNF‐AS in CRC pathogenesis have not been reported yet. Interestingly, Chen et al using dual luciferase reporter and ChIP assays confirmed that EZH2 repressed the expression of GSK‐3β through interacting with transcription binding motifs in the promoter of the GSK‐3β gene in cervical cancer cells . In this study, we thus speculated that lncRNA BDNF‐AS functioned as a tumour suppressor in CRC progression by suppressing GSK‐3β expression through binding to EZH2 and H3K27me3 with the GSK‐3β promoter.…”

Cancer driver mutations in endometriosis: Variations on the major theme of fibrogenesis

“…In fact, EZH2 is found to induce EMT and thus fibrogenesis in endometriosis, and there are signs to indicate that platelet aggregation in lesions may be responsible for EZH2 activation . Importantly, EZH2 may mediate the repression of GSK‐3β and TP53 and promote the activation of the Wnt/β‐catenin signaling pathway . The profibrogenic role of the Wnt/β‐catenin signaling pathway in endometriosis has recently been reported .…”

“…and promote the activation of the Wnt/β-catenin signaling pathway. 127 The profibrogenic role of the Wnt/β-catenin signaling pathway in endometriosis has recently been reported. 128 133,134 In addition, TET1, TET2, and TET3 expression is reported to be decreased.…”