Hsa-LINC02418/mmu-4930573I07Rik regulated by METTL3 dictates anti-PD-L1 immunotherapeutic efficacy via enhancement of Trim21-mediated PD-L1 ubiquitination

• Published in: Journal for immunotherapy of cancer Vol. 11; no. 12; p. e007415
• Main Authors: Sun, Zhijia, Mai, Haixing, Xue, Chunyuan, Fan, Zhongyi, Li, Jiangbo, Chen, Hairui, Huo, Nan, Kang, Xiaofeng, Tang, Chuanhao, Fang, Liaoxin, Zhao, Hui, Han, Yuchen, Sun, Chao, Peng, Huanyan, Du, Yimeng, Yang, Jing, Du, Nan, Xu, Xiaojie
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd 01.12.2023; BMJ Publishing Group LTD; BMJ Publishing Group
• Series: Original research
• Subjects: Animals; B7-H1 Antigen - metabolism; Biotechnology industry; Carcinoma, Non-Small-Cell Lung - pathology; Cells; Gene expression; Humans; immune checkpoint inhibitors; Immunotherapy; Immunotherapy Biomarkers; Ligands; Lung cancer; lung neoplasms; Lung Neoplasms - pathology; Lymphocytes; Medical prognosis; Methyltransferases - genetics; Methyltransferases - metabolism; Methyltransferases - therapeutic use; Mice; non-small cell lung cancer; Programmed Cell Death 1 Receptor; RNA - metabolism; RNA - therapeutic use; Statistical analysis; Tumors; Ubiquitination; non-small cell lung cancer; programmed cell death 1 receptor; immune checkpoint inhibitors; lung neoplasms
• ISSN: 2051-1426; 2051-1426
• DOI: 10.1136/jitc-2023-007415

BackgroundLimited response to programmed death ligand-1 (PD-L1)/programmed death 1 (PD-1) immunotherapy is a major hindrance of checkpoint immunotherapy in non-small cell lung cancer (NSCLC). The abundance of PD-L1 on the tumor cell surface is crucial for the responsiveness of PD-1/PD-L1 immunotherapy. However, the negative control of PD-L1 expression and the physiological significance of the PD-L1 inhibition in NSCLC immunotherapy remain obscure.MethodsBioinformatics analysis was performed to profile and investigate the long non-coding RNAs that negatively correlated with PD-L1 expression and positively correlated with CD8+T cell infiltration in NSCLC. Immunofluorescence, in vitro PD-1 binding assay, T cell-induced apoptosis assays and in vivo syngeneic mouse models were used to investigate the functional roles of LINC02418 and mmu-4930573I07Rik in regulating anti-PD-L1 therapeutic efficacy in NSCLC. The molecular mechanism of LINC02418-enhanced PD-L1 downregulation was explored by immunoprecipitation, RNA immunoprecipitation (RIP), and ubiquitination assays. RIP, luciferase reporter, and messenger RNA degradation assays were used to investigate the m6A modification of LINC02418 or mmu-4930573I07Rik expression. Bioinformatics analysis and immunohistochemistry (IHC) verification were performed to determine the significance of LINC02418, PD-L1 expression and CD8+T cell infiltration.ResultsLINC02418 is a negative regulator of PD-L1 expression that positively correlated with CD8+T cell infiltration, predicting favorable clinical outcomes for patients with NSCLC. LINC02418 downregulates PD-L1 expression by enhancing PD-L1 ubiquitination mediated by E3 ligase Trim21. Both hsa-LINC02418 and mmu-4930573I07Rik (its homologous RNA in mice) regulate PD-L1 therapeutic efficacy in NSCLC via Trim21, inducing T cell-induced apoptosis in vitro and in vivo. Furthermore, METTL3 inhibition via N6-methyladenosine (m6A) modification mediated by YTHDF2 reader upregulates hsa-LINC02418 and mmu-4930573I07Rik. In patients with NSCLC, LINC02418 expression is inversely correlated with PD-L1 expression and positively correlated with CD8+T infiltration.ConclusionLINC02418 functions as a negative regulator of PD-L1 expression in NSCLC cells by promoting the degradation of PD-L1 through the ubiquitin-proteasome pathway. The expression of LINC02418 is regulated by METTL3/YTHDF2-mediated m6A modification. This study illuminates the underlying mechanisms of PD-L1 negative regulation and presents a promising target for improving the effectiveness of anti-PD-L1 therapy in NSCLC.