Abstract
Enhancer of zeste homolog 2 (EZH2) is the catalytic unit of polycomb repressive complex 2 (PRC2) which epigenetically silences many genes involved in tumor-suppressive mechanisms via the trimethylation of lysine 27 of histone H3 (H3K27me3). We recently found that overexpression of EZH2 was associated with poor outcome of glioblastoma (GBM). In this study, we examined the antitumor effects of the EZH2 inhibitor GSK343 on glioma cells in vitro and in vivo. The proliferation and cell cycle of glioma cells was measured. Wound healing assay and transwell invasion assay were performed to evaluate the capacity of migration and invasion of glioma cells. Western blot, qPCR, immunoprecipitation and fluorescent staining were used to test the levels of EZH2 and associated proteins. Spheroid formation assay and clonogenic assays were conducted to assess the stemness of glioma stem cells. Finally, the effect of GSK343 was measured through a nude mice model with intracranially xenotransplanted glioma. We found that GSK343 reduced proliferation, attenuated cell motility and reversed epithelial-mesenchymal transition in U87 and LN229 glioma cells. GSK343 also suppressed the stemness of cell lines and patient derived glioma stem cells. Further, GSK343 inhibited histone H3K27 methylation and upregulated the expression of EZH2 target genes thereby regulating the levels of markers involved in epithelial-mesenchymal transition and stemness. Taken together, our results indicate that GSK343 could be a potential drug against glioblastoma.
Highlights
The polycomb repressive complex 2 (PRC2), an epigenetic repressor, is a multi-subunit complex consisting of three core subunits including enhancer of zeste homolog 2 (EZH2), suppressor of zeste 12 (SUZ12), and embryonic ectoderm development (EED)
The protein levels of Enhancer of zeste homolog 2 (EZH2) and H3K27me3 were both down-regulated, GSK343 had little impact on the function of TJ905 glioma cells (Supplementary Figure 1B-1E). These results indicated that GSK343 was an EZH2-dependent inhibitor
These alterations are distinct from common genetic alterations such as mutations or amplification because epigenetic regulation can be reversed by enzyme inhibitors including histone deacetylases, histone methyltransferases, and DNA
Summary
The polycomb repressive complex 2 (PRC2), an epigenetic repressor, is a multi-subunit complex consisting of three core subunits including enhancer of zeste homolog 2 (EZH2), suppressor of zeste 12 (SUZ12), and embryonic ectoderm development (EED). EZH2, the catalytic component of PRC2, transfers a methyl group from S-adenosyl methionine (SAM) to lysine 27 of histone H3 (H3K27) through its SET domain. Cooperation with SUZ12 and EED is necessary for full performance of PRC2 histone lysine methyltransferase activity [1, 2]. Www.impactjournals.com/oncotarget serves as a docking site for DNA methyltransferases and the monoubiquitylation of H2AK119 catalyzed by PRC1 [3, 4]. PRC2 silences many genes involved in cell proliferation, cell-cycle regulation, cell differentiation, and self-renewal [5,6,7,8,9,10,11]. Overexpression of EZH2 confers pro-oncogenic functions that are implicated in a broad spectrum of solid tumors [12,13,14,15,16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
