Circular EZH2-encoded EZH2-92aa mediates immune evasion in glioblastoma via inhibition of surface NKG2D ligands

• Published in: Nature communications Vol. 13; no. 1; p. 4795
• Main Authors: Zhong, Jian, Yang, Xuesong, Chen, Junju, He, Kejun, Gao, Xinya, Wu, Xujia, Zhang, Maolei, Zhou, Huangkai, Xiao, Feizhe, An, Lele, Wang, Xiuxing, Shi, Yu, Zhang, Nu
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 15.08.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 13/1; 13/109; 13/31; 13/89; 14/19; 38/32; 38/91; 631/250/580/1884; 631/67/1922; 631/67/71; 64/60; 82/29; 82/58; Biocompatibility; Brain; Brain cancer; Brain tumors; Circular RNA; Cytotoxicity; DNA helicase; Glioblastoma; Humanities and Social Sciences; Immune evasion; Immunotherapy; Ligands; Major histocompatibility complex; multidisciplinary; Natural killer cells; NKG2 antigen; PD-1 protein; Polypeptides; Proteins; Science; Science (multidisciplinary); Stem cells; Toxicity; Tumors
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-022-32311-2

Glioblastoma (GBM) is a highly aggressive primary brain tumour and is resistant to nearly all available treatments, including natural killer (NK) cell immunotherapy. However, the factors mediating NK cell evasion in GBM remain largely unclear. Here, we report that EZH2-92aa, a protein encoded by circular EZH2, is overexpressed in GBM and induces the immune evasion of GBM stem cells (GSCs) from NK cells. Positively regulated by DEAD-box helicase 3 (DDX3), EZH2-92aa directly binds the major histocompatibility complex class I polypeptide-related sequence A/B (MICA/B) promoters and represses their transcription; it also indirectly represses UL16-binding protein (ULBP) transcription by stabilizing EZH2. The downregulation of NK group 2D ligands (NKG2DLs, including MICA/B and ULBPs) in GSCs mediates NK cell resistance. Moreover, stable EZH2-92aa knockdown enhances NK cell-mediated GSC eradication in vitro and in vivo and synergizes with anti-PD1 therapy. Our results highlight the immunosuppressive function of EZH2-92aa in inhibiting the NK cell response in GBM and the clinical potential of targeting EZH2-92aa for NK-cell-directed immune therapy. Glioblastoma (GBM) is a highly aggressive brain tumor, frequently resistant to therapies, including natural killer (NK) cell based immunotherapy. Here, the authors show that the circular RNA EZH2 is highly expressed in GBM and encodes the peptide EZH2-92aa, whose expression is associated with inhibition of NK cell cytotoxicity.