The EZH2 inhibitor GSK343 suppresses cancer stem-like phenotypes and reverses mesenchymal transition in glioma cells

Abstract

// Tianfu Yu 1, * , Yingyi Wang 1, * , Qi Hu 1, * , WeiNing Wu 1, * , Youzhi Wu 2 , Wenjin Wei 3 , Dongfeng Han 4 , Yongping You 1 , Ning Lin 5 and Ning Liu 1 1 Department of Neurosurgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China 2 Department of Neurosurgery, Nanjing First Hospital, Nanjing Medical University, Nanjing, China 3 Department of Neurosurgery, The Affiliated Ganzhou Hospital of Nanchang University, Ganzhou, Jiangxi Province, China 4 Department of Neurosurgery, Xuzhou Central Hospital, Xuzhou, China 5 Department of Neurosurgery, The First People’s Hospital Chuzhou, Chuzhou, China * These authors have contributed equally to this work Correspondence to: Ning Lin, email: lin2007512@vip.163.com Ning Liu, email: liuning0853@126.com Keywords: EZH2; EZH2 inhibitor; epigenetics; glioma; glioma stem cell Received: April 18, 2017      Accepted: August 04, 2017      Published: September 27, 2017 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.