Inhibiting PD-L1 palmitoylation enhances T-cell immune responses against tumours

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Abstract

Checkpoint blockade therapy targeting the programmed-death ligand 1 (PD-L1) and its receptor programmed cell death 1 promotes T-cell-mediated immunosurveillance against tumours, and has been associated with marked clinical benefit in cancer patients. Antibodies against PD-L1 function by blocking PD-L1 on the cell surface, but intracellular storage of PD-L1 and its active redistribution to the cell membrane can minimize the therapeutic benefits, which highlights the importance of targeting PD-L1 throughout the whole cell. Here, we show that PD-L1 is palmitoylated in its cytoplasmic domain, and that this lipid modification stabilizes PD-L1 by blocking its ubiquitination, consequently suppressing PD-L1 degradation by lysosomes. We identified palmitoyltransferase ZDHHC3 (DHHC3) as the main acyltransferase required for the palmitoylation of PD-L1, and show that the inhibition of PD-L1 palmitoylation via 2-bromopalmitate, or the silencing of DHHC3, activates antitumour immunity in vitro and in mice bearing MC38 tumour cells. We also designed a competitive inhibitor of PD-L1 palmitoylation that decreases PD-L1 expression in tumour cells to enhance T-cell immunity against the tumours. These findings suggest new strategies for overcoming PD-L1-mediated immune evasion in cancer.

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Fig. 1: Targeting palmitoylation-depleted PD-L1 in tumour cells.
Fig. 2: Identification of the palmitoylation site on PD-L1.
Fig. 3: An intrinsic lysosomal sorting signal in PD-L1 is masked by palmitoylation.
Fig. 4: PD-L1 is palmitoylated by DHHC3 acyltransferase.
Fig. 5: Palmitoylation blocks PD-L1 ubiquitination and ESCRT-mediated trafficking to the MVB.
Fig. 6: Targeting PD-L1 palmitoylation-activated anti-cancer immunity.
Fig. 7: Targeting PD-L1 palmitoylation with a peptidic inhibitor.
Fig. 8: Palmitoylation stabilizes PD-L1 by blocking its ubiquitination and lysosomal degradation.

Data availability

The authors declare that all data supporting the findings of this study are available within the paper and its Supplementary Information files.

Change history

  • 11 April 2019

    In the version of this Article originally published, ‘palmitoyltransferase ZDHHC3 (DHHC3)’ was incorrectly referred to as an ‘acetyltransferase’ rather than an as an ‘acyltransferase’; this has now been corrected in five instances. In Fig. 3a, the label for the bottom row of the blots was mistakenly written as ‘GAPHD’; it should have read ‘GAPDH’. In the two right-most panels of Fig. 4j, the antibody labels ‘α-PD-L1’ for the reciprocal co-immunoprecipitation of DHHC3 were incorrect; they should have been ‘α-DHHC3’. These errors have been corrected in all versions of the Article.

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Acknowledgements

This project was supported by grants from the National Key Research and Development Plan (2016YFC0906000, 2016YFC0906003, 2016YFC0906002 and 2017YFC0906600), National Natural Science Foundation of China (81572326, 81322036, 81421001, 81773752, 81702969, 81874050, 21335002 and 31671360), Key Program of the Science and Technology Bureau of Sichuan (number 2017SZ00005), Top-Notch Young Talents Program of China (ZTZ2015-48), ‘Tang Scholar’ programme (JX-2017), Shanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support (20152514), ‘ShuGuang’ project supported by the Shanghai Municipal Education Commission and Shanghai Education Development Foundation (15SG16), National Key Technology Support Program (2015BAI13B07 to J.X.), and Natural Science Foundation of Shanghai (18ZR1402800 to C.F.). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

Author information

H.Y. performed the in vitro and in vivo experiments, analysed the data and wrote the manuscript. J.L. performed the in vivo experiments and analysed the data. C.L. performed the in vitro experiments. H.S. designed the in vivo experiments and analysed the data. J.-P.B. contributed to the experimental design, analysed the data and wrote the manuscript. H.W. performed the in vitro experiments. H.L. and C.F. contributed the anti-palmitoylation antibody and analysed the relevant data. Y.Z., L.L., X.Z. and C.W. analysed the peptide toxicity data in different organs/samples, as well as the tissue microarray data. Y.X. contributed analysis tools and designed the mutagenesis experiment. Y.C. analysed the peptide toxicity data. J.X. supervised the project, conceived and designed the experiments and peptides, analysed the data and wrote the manuscript.

Correspondence to Jie Xu.

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Yao, H., Lan, J., Li, C. et al. Inhibiting PD-L1 palmitoylation enhances T-cell immune responses against tumours. Nat Biomed Eng 3, 306–317 (2019) doi:10.1038/s41551-019-0375-6

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