Nuclear PD-L1 compartmentalization suppresses tumorigenesis and overcomes immunocheckpoint therapy resistance in mice via histone macroH2A1
Yong Liu, … , Mien-Chie Hung, Junwei Hou
Yong Liu, … , Mien-Chie Hung, Junwei Hou
Published November 15, 2024
Citation Information: J Clin Invest. 2024;134(22):e181314. https://doi.org/10.1172/JCI181314.
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Research Article Cell biology Oncology

Nuclear PD-L1 compartmentalization suppresses tumorigenesis and overcomes immunocheckpoint therapy resistance in mice via histone macroH2A1

Abstract

Canonically PD-L1 functions as the inhibitory immune checkpoint on cell surface. Recent studies have observed PD-L1 expression in the nucleus of cancer cells. But the biological function of nuclear PD-L1 (nPD-L1) in tumor growth and antitumor immunity is unclear. Here we enforced nPD-L1 expression and established stable cells. nPD-L1 suppressed tumorigenesis and aggressiveness in vitro and in vivo. Compared with PD-L1 deletion, nPD-L1 expression repressed tumor growth and improved survival more markedly in immunocompetent mice. Phosphorylated AMPKα (p-AMPKα) facilitated nuclear PD-L1 compartmentalization and then cooperated with it to directly phosphorylate S146 of histone variant macroH2A1 (mH2A1) to epigenetically activate expression of genes of cellular senescence, JAK/STAT, and Hippo signaling pathways. Lipoic acid (LA) that induced nuclear PD-L1 translocation suppressed tumorigenesis and boosted antitumor immunity. Importantly, LA treatment synergized with PD-1 antibody and overcame immune checkpoint blockade (ICB) resistance, which likely resulted from nPD-L1–increased MHC-I expression and sensitivity of tumor cells to interferon-γ. These findings offer a conceptual advance for PD-L1 function and suggest LA as a promising therapeutic option for overcoming ICB resistance.

Authors

Yong Liu, Zhi Yang, Shuanglian Wang, Rui Miao, Chiung-Wen Mary Chang, Jingyu Zhang, Xin Zhang, Mien-Chie Hung, Junwei Hou

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Figure 7

nPD-L1 cooperated with p-AMPKα to phosphorylate S146 of mH2A1 to epigenetically activate gene expression.

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nPD-L1 cooperated with p-AMPKα to phosphorylate S146 of mH2A1 to epigene...
(A) In vitro phosphorylation of histone mH2A1 by AMPKα was performed. Anti–thiophosphate ester antibody was used to detect mH2A1 phosphorylation. (B) AMPK phospho-motif of mH2A1 and conservative amino acid sequence across species. (C) In vitro phosphorylation of wild-type (WT) and mutant mH2A1. S140A was used as a negative control. (D) Co-IP analysis of mH2A1 phosphorylation at the site S146 in Hep3B cells treated with LA (1 mM). (E) Immunoblotting of mH2A1-p146 in LA-treated Hep3B cells and Hep3B-PD-L1-KO-nPD-L1 stable cells. (F) Co-IP analysis of the interactions of mH2A1-p146, PD-L1, and p-AMPKα. (G) Analysis of LA-induced activation of AMPKα, mH2A1, and nPD-L1 and their interaction by co-IP and cellular fraction in Hep3B cells. (H) In vitro phosphorylation of mH2A1 at the site S146 by the cooperation of PD-L1 and p-AMPKα. (I) Cellular fraction and co-IP analysis of mH2A1-p146 phosphorylation in 293T cells expressing genes as indicated. AICAR treatment (500 μM, 24 hours). (J) Cellular fraction analysis of PD-L1/p-AMPKα–induced mH2A1-p146 phosphorylation in Hep3B-PD-L1-KO stable cells treated with AICAR. (K) Cellular fraction analysis of PD-L1/p-AMPKα–induced mH2A1-p146 phosphorylation in Hep3B-AMPKα-KO stable cells treated with AICAR. (L) Cellular fraction analysis of AICAR-induced mH2A1-p146 phosphorylation in Hep3B cells with overexpression of wild-type (WT) or S146A-mutated (Mut) mH2A1. (M) Quantitative RT-PCR analysis of the indicated genes from mH2A1-WT or mH2A1-Mut groups in Hep3B cells. (N) Protein level of genes in M. Data shown are mean ± SD. Thiop-ester, thiophosphate ester.