The aryl hydrocarbon receptor suppresses immunity to oral squamous cell carcinoma through immune checkpoint regulation
Menée in vitro et à l'aide de modèles murins de carcinome épidermoïde de la cavité buccale, cette étude met en évidence un mécanisme par lequel le récepteur d'aryl d'hydrocarbone supprime l'immunité anticancéreuse via la régulation du point de contrôle immunitaire
Immune checkpoint inhibitors have emerged as critical therapeutics for several cancer types, including head and neck squamous cell carcinoma. However, enthusiasm remains constrained by the fact that only a minority of patients benefit. Therefore, there is a need to identify new immunotherapy targets. Here, we provide evidence supporting our hypothesis that the aryl hydrocarbon receptor (AhR) influences multiple immune checkpoints in a model of oral squamous cell carcinoma (OSCC). Remarkably, transplant of AhR-deleted OSCC cells generates completely protective tumor immunity characterized by a decrease in multiple immune checkpoints (PD-L1, CD39, CTLA4, PD1, and Lag3) on malignant and/or immune cells. These results have important implications for understanding the biology of cancer immunosuppression and for targeting the AhR for cancer immunotherapy.Immune checkpoint inhibitors represent some of the most important cancer treatments developed in the last 20 y. However, existing immunotherapy approaches benefit only a minority of patients. Here, we provide evidence that the aryl hydrocarbon receptor (AhR) is a central player in the regulation of multiple immune checkpoints in oral squamous cell carcinoma (OSCC). Orthotopic transplant of mouse OSCC cells from which the AhR has been deleted (MOC1AhR-KO) results, within 1 wk, in the growth of small tumors that are then completely rejected within 2 wk, concomitant with an increase in activated T cells in tumor-draining lymph nodes (tdLNs) and T cell signaling within the tumor. By 2 wk, AhR+ control cells (MOC1Cas9), but not MOC1AhR-KO cells up-regulate exhaustion pathways in the tumor-infiltrating T cells and expression of checkpoint molecules on CD4+ T cells (PD-1, CTLA4, Lag3, and CD39) and macrophages, dendritic cells, and Ly6G+ myeloid cells (PD-L1 and CD39) in tdLNs. Notably, MOC1AhR-KO cell transplant renders mice 100% immune to later challenge with wild-type tumors. Analysis of altered signaling pathways within MOC1AhR-KO cells shows that the AhR controls baseline and IFNγ-induced Ido and PD-L1 expression, the latter of which occurs through direct transcriptional control. These observations 1) confirm the importance of malignant cell AhR in suppression of tumor immunity, 2) demonstrate the involvement of the AhR in IFNγ control of PD-L1 and IDO expression in the cancer context, and 3) suggest that the AhR is a viable target for modulation of multiple immune checkpoints.All study data are included in the article and/or supporting information.