Canagliflozin primes antitumor immunity by triggering PD-L1 degradation in endocytic recycling
Ling Ding, … , Qiaojun He, Bo Yang
Ling Ding, … , Qiaojun He, Bo Yang
Published January 3, 2023
Citation Information: J Clin Invest. 2023;133(1):e154754. https://doi.org/10.1172/JCI154754.
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Research Article Immunology

Canagliflozin primes antitumor immunity by triggering PD-L1 degradation in endocytic recycling

Abstract

Understanding the regulatory mechanisms of PD-L1 expression in tumors provides key clues for improving immune checkpoint blockade efficacy or developing novel oncoimmunotherapy. Here, we showed that the FDA-approved sodium-glucose cotransporter-2 (SGLT2) inhibitor canagliflozin dramatically suppressed PD-L1 expression and enhanced T cell–mediated cytotoxicity. Mechanistic study revealed that SGLT2 colocalized with PD-L1 at the plasma membrane and recycling endosomes and thereby prevented PD-L1 from proteasome-mediated degradation. Canagliflozin disturbed the physical interaction between SGLT2 and PD-L1 and subsequently allowed the recognition of PD-L1 by Cullin3SPOP E3 ligase, which triggered the ubiquitination and proteasome-mediated degradation of PD-L1. In mouse models and humanized immune-transformation models, either canagliflozin treatment or SGLT2 silencing significantly reduced PD-L1 expression and limited tumor progression — to a level equal to the PD-1 mAb — which was correlated with an increase in the activity of antitumor cytotoxic T cells. Notably, prolonged progression-free survival and overall survival curves were observed in the group of PD-1 mAb–treated patients with non–small cell lung cancer with high expression of SGLT2. Therefore, our study identifies a regulator of cell surface PD-L1, provides a ready-to-use small-molecule drug for PD-L1 degradation, and highlights a potential therapeutic target to overcome immune evasion by tumor cells.

Authors

Ling Ding, Xi Chen, Wenxin Zhang, Xiaoyang Dai, Hongjie Guo, Xiaohui Pan, Yanjun Xu, Jianguo Feng, Meng Yuan, Xiaomeng Gao, Jian Wang, Xiaqing Xu, Sicheng Li, Honghai Wu, Ji Cao, Qiaojun He, Bo Yang

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Figure 2

Canagliflozin reduces PD-L1 expression through its pharmacological target SGLT2.

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Canagliflozin reduces PD-L1 expression through its pharmacological targe...
(A) Western blots showing that depletion of SGLT2 induced PD-L1 degradation. H1299 cells were treated with siRNAs targeting SGLT2. H292 cells were treated with shRNAs targeting SGLT2 as indicated. (B) Canagliflozin-caused PD-L1 decrease was abolished in the absence of SGLT2. (C) Overexpression of SGLT2 upregulated PD-L1 expression. (D) Depletion of GLUT1 had no effect on PD-L1 expression. H1299 cells were treated with siRNA-GLUT1 and the level of PD-L1 was detected by Western blotting. (E) Canagliflozin did not influence the abundance of glycolytic metabolites, whereas silencing of GLUT1 significantly reduced the abundance of glycolytic metabolites (n = 3). (F) Confocal analysis revealed the colocalization of SGLT2 and PD-L1 proteins in H1299 cells. Scale bar: 5 μm. (G) Interaction of SGLT2 with PD-L1 was detergent-sensitive. SGLT2-GFP and PD-L1-HA were transfected into HEK 293T cells for 24 hours. Cells were then lysed in 1% Digitonin (Dig) or 0.5% Digitonin/ 1% Triton X-100 (Tx) and immunoprecipitated with the anti-HA, followed by analysis using anti-GFP antibody. (H) Canagliflozin disrupted the interaction between SGLT2 and PD-L1. (I) Intracellular domain (aa 548–650) of SGLT2 was responsible for its interaction with PD-L1. (J) Downregulation of PD-L1 caused by canagliflozin was abolished when SGLT2 lost its plasma–membrane targeting region. H292 cells were treated with canagliflozin for 24 hours after transfection with SGLT2-GFP or SGLT2-Δ1-26-GFP. (K) Downregulation of PD-L1 caused by canagliflozin was abolished when the SGLT2 sodium-binding site was mutated. H292 cells were treated with canagliflozin for 24 hours after transfection with SGLT2 or SGLT2-R300A plasmids. Data were presented as the mean ± SD of triplicate experiments. Statistical significance was determined by unpaired 2-tailed Students’ t test. ***P < 0.001.