Tumor-Repopulating Cells Induce PD-1 Expression in CD8+ T Cells by Transferring Kynurenine and AhR Activation

Publication date: 12 March 2018
Source:Cancer Cell, Volume 33, Issue 3
Author(s): Yuying Liu, Xiaoyu Liang, Wenqian Dong, Yi Fang, Jiadi Lv, Tianzhen Zhang, Roland Fiskesund, Jing Xie, Jinyan Liu, Xiaonan Yin, Xun Jin, Degao Chen, Ke Tang, Jingwei Ma, Huafeng Zhang, Jing Yu, Jun Yan, Huaping Liang, Siqi Mo, Feiran Cheng, Yabo Zhou, Haizeng Zhang, Jing Wang, Jingnan Li, Yang Chen, Bing Cui, Zhuo-Wei Hu, Xuetao Cao, F. Xiao-Feng Qin, Bo Huang
Despite the clinical successes fostered by immune checkpoint inhibitors, mechanisms underlying PD-1 upregulation in tumor-infiltrating T cells remain an enigma. Here, we show that tumor-repopulating cells (TRCs) drive PD-1 upregulation in CD8⁺ T cells through a transcellular kynurenine (Kyn)-aryl hydrocarbon receptor (AhR) pathway. Interferon-γ produced by CD8⁺ T cells stimulates release of high levels of Kyn produced by TRCs, which is transferred into adjacent CD8⁺ T cells via the transporters SLC7A8 and PAT4. Kyn induces and activates AhR and thereby upregulates PD-1 expression. This Kyn-AhR pathway is confirmed in both tumor-bearing mice and cancer patients and its blockade enhances antitumor adoptive T cell therapy efficacy. Thus, we uncovered a mechanism of PD-1 upregulation with potential tumor immunotherapeutic applications.

Teaser

Liu et al. find that tumor-repopulating cells (TRCs) regulate PD-1 expression in CD8⁺ T cells. TRCs secrete kynurenine that is taken up by T cells and activates AhR, which directly regulates PD-1 expression. Blockade of this pathway enhances adoptive T cell therapy efficacy in a mouse melanoma model.


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