Targeting NEK2 attenuates glioblastoma growth and radioresistance by destabilizing histone methyltransferase EZH2
Jia Wang, … , Maode Wang, Ichiro Nakano
Jia Wang, … , Maode Wang, Ichiro Nakano
Published July 24, 2017
Citation Information: J Clin Invest. 2017;127(8):3075-3089. https://doi.org/10.1172/JCI89092.
View: Text | PDF | Expression of Concern | Retraction
Research Article Oncology Article has an altmetric score of 76

Targeting NEK2 attenuates glioblastoma growth and radioresistance by destabilizing histone methyltransferase EZH2

Abstract

Accumulating evidence suggests that glioma stem cells (GSCs) are important therapeutic targets in glioblastoma (GBM). In this study, we identified NIMA-related kinase 2 (NEK2) as a functional binding protein of enhancer of zeste homolog 2 (EZH2) that plays a critical role in the posttranslational regulation of EZH2 protein in GSCs. NEK2 was among the most differentially expressed kinase-encoding genes in GSC-containing cultures (glioma spheres), and it was required for in vitro clonogenicity, in vivo tumor propagation, and radioresistance. Mechanistically, the formation of a protein complex comprising NEK2 and EZH2 in glioma spheres phosphorylated and then protected EZH2 from ubiquitination-dependent protein degradation in a NEK2 kinase activity–dependent manner. Clinically, NEK2 expression in patients with glioma was closely associated with EZH2 expression and correlated with a poor prognosis. NEK2 expression was also substantially elevated in recurrent tumors after therapeutic failure compared with primary untreated tumors in matched GBM patients. We designed a NEK2 kinase inhibitor, compound 3a (CMP3a), which efficiently attenuated GBM growth in a mouse model and exhibited a synergistic effect with radiotherapy. These data demonstrate a key role for NEK2 in maintaining GSCs in GBM by stabilizing the EZH2 protein and introduce the small-molecule inhibitor CMP3a as a potential therapeutic agent for GBM.

Authors

Jia Wang, Peng Cheng, Marat S. Pavlyukov, Hai Yu, Zhuo Zhang, Sung-Hak Kim, Mutsuko Minata, Ahmed Mohyeldin, Wanfu Xie, Dongquan Chen, Violaine Goidts, Brendan Frett, Wenhao Hu, Hongyu Li, Yong Jae Shin, Yeri Lee, Do-Hyun Nam, Harley I. Kornblum, Maode Wang, Ichiro Nakano

×

Figure 6

NEK2 promotes radioresistance in glioma spheres by maintaining EZH2 protein stability.

Options: View larger image (or click on image) Download as PowerPoint
NEK2 promotes radioresistance in glioma spheres by maintaining EZH2 prot...
(A) mRNA expression analysis (GSE67089) showed that NEK2 was highly enriched in glioma spheres compared with normal astrocytes. *P < 0.05 and ***P < 0.001, by 1-way ANOVA followed by Dunnett’s post-hoc test. n = 6 for PN, n = 3 for MES and n = 1 for NHAs. 3 or more replicates were performed at the same time. (B) Genome-wide transcriptome microarray analysis showed that NEK2 was one of the most upregulated kinase-encoding genes in post-radiation glioma spheres (12 Gy) compared with naive glioma spheres. (C) qRT-PCR for NEK2 in post-radiation 528 glioma spheres (12 Gy) compared with naive 528 glioma spheres (n = 3). ***P < 0.001, by 2-tailed t test. (D) Western blotting for NEK2 and EZH2 in 528 glioma spheres treated with radiation (12 Gy) compared with naive 528 glioma spheres. (E and F) Flow cytometric analysis for apoptosis (E) and Western blotting for NEK2 and EZH2 expression (F) in 528 glioma spheres pretransduced with shNEK2 no. 1, shNEK2 no. 2 or, shNT and then treated with or without (Non) radiation (12 Gy). (G) Representative IHC images for NEK2 expression in primary untreated tumors and post-radiation recurrent tumors from matched GBM patients. Scale bars: 50 mm. (H) Percentage of NEK2 positive-stained cells in primary untreated tumors and post-radiation recurrent tumors from matched GBM patients (n = 5). *P < 0.05, by 2-tailed t test.