IL-6/JAK1 pathway drives PD-L1 Y112 phosphorylation to promote cancer immune evasion
Li-Chuan Chan, … , Shao-Chun Wang, Mien-Chie Hung
Li-Chuan Chan, … , Shao-Chun Wang, Mien-Chie Hung
Published July 15, 2019
Citation Information: J Clin Invest. 2019;129(8):3324-3338. https://doi.org/10.1172/JCI126022.
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Research Article Cell biology Oncology

IL-6/JAK1 pathway drives PD-L1 Y112 phosphorylation to promote cancer immune evasion

Abstract

Glycosylation of immune receptors and ligands, such as T cell receptor and coinhibitory molecules, regulates immune signaling activation and immune surveillance. However, how oncogenic signaling initiates glycosylation of coinhibitory molecules to induce immunosuppression remains unclear. Here we show that IL-6–activated JAK1 phosphorylates programmed death-ligand 1 (PD-L1) Tyr112, which recruits the endoplasmic reticulum–associated N-glycosyltransferase STT3A to catalyze PD-L1 glycosylation and maintain PD-L1 stability. Targeting of IL-6 by IL-6 antibody induced synergistic T cell killing effects when combined with anti–T cell immunoglobulin mucin-3 (anti–Tim-3) therapy in animal models. A positive correlation between IL-6 and PD-L1 expression was also observed in hepatocellular carcinoma patient tumor tissues. These results identify a mechanism regulating PD-L1 glycosylation initiation and suggest the combination of anti–IL-6 and anti–Tim-3 as an effective marker-guided therapeutic strategy.

Authors

Li-Chuan Chan, Chia-Wei Li, Weiya Xia, Jung-Mao Hsu, Heng-Huan Lee, Jong-Ho Cha, Hung-Ling Wang, Wen-Hao Yang, Er-Yen Yen, Wei-Chao Chang, Zhengyu Zha, Seung-Oe Lim, Yun-Ju Lai, Chunxiao Liu, Jielin Liu, Qiongzhu Dong, Yi Yang, Linlin Sun, Yongkun Wei, Lei Nie, Jennifer L. Hsu, Hui Li, Qinghai Ye, Manal M. Hassan, Hesham M. Amin, Ahmed O. Kaseb, Xin Lin, Shao-Chun Wang, Mien-Chie Hung

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Figure 6

JAK1 phosphorylates PD-L1 at Y112 and upregulates PD-L1 expression.

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JAK1 phosphorylates PD-L1 at Y112 and upregulates PD-L1 expression. (A) ...
(A) In vitro kinase assay and WB analysis of tyrosine phosphorylation (4G10) of recombinant PD-L1 WT and PD-L1 Y112F protein. Data show relative fold change of tyrosine phosphorylation on PD-L1 protein normalized to PD-L1 WT protein with JAK1 kinase (#3). (B) Cell lysates were subjected to IP followed by WB analysis to determine PD-L1 protein levels in SK-HEP-1 ngPD-L1 cells treated with or without IL-6 (20 ng/mL, 30 minutes) and ruxolitinib (10 μmol/L, 30 minutes) using the indicated antibodies, which were preincubated with cold or hot PD-L1 peptides (p-Y112). (C) WB analysis of exogenous PD-L1 expression in FLAG–PD-L1 WT–SK-HEP-1 or Y112F–SK-HEP-1 cells with or without exposure to IL-6 (20 ng/mL, 18 hours), ruxolitinib (10 μmol/L, 18 hours), and/or MG132 (10 μmol/L, 6 hours). SE, short exposure; LE, long exposure. (D) Flow cytometric analysis of cell surface PD-L1 level in FLAG–PD-L1 WT–SK-HEP-1 or Y112F–SK-HEP-1 cells with or without exposure to IL-6 and/or ruxolitinib (n = 3). Data show relative fold change in the MFI of PD-L1. Error bars represent mean ± SD. ****P < 0.0001, 1-way ANOVA (A and D).