β2-肾上腺素受体（β2-ARs）是细胞膜跨越G蛋白偶联受体（GPCRs），在生理上参与应激相关反应。在许多肿瘤中，β2-ARs信号传导推动肿瘤发展和转化，并促进对治疗的抵抗。在HNSCC细胞系中，β2-AR选择性抑制通过影响p38/NF-kB致癌途径，同时减少NRF-2介导的抗氧化细胞反应，协同增强MEK 1/2的细胞毒性效应。本研究旨在验证β2-AR阻断的抗肿瘤效果以及与MEK/ERK和EGFR途径抑制的协同作用，在HNSCC的临床前正位小鼠模型中。有趣的是，我们发现在肿瘤中存在着强烈的β2-ARs表达，而β2-ARs抑制剂（ICI）和EGFR抗体Cetuximab（CTX）的长期治疗组合明显减少了这种表达。β2-ARs的下调与小鼠体内显著的肿瘤生长延迟相一致，这是由于MEK/ERK磷酸化阻断引起的MAPK信号关闭。我们还证明，ICI和CTX的联合给药通过阻断NRF-2的核转位，不平衡了细胞ROS稳态，并导致抗氧化酶表达的下调。我们的发现在临床前体内模型首次强调了β2-ARs抑制剂在HNSCC治疗中的有效性，尤其是与CTX联合使用，后者是难以切除HNSCC的标准治疗方法。©2023。作者。

The β2-Adrenergic receptor (β2-ARs) is a cell membrane-spanning G protein-coupled receptors (GPCRs) physiologically involved in stress-related response. In many cancers, the β2-ARs signaling drives the tumor development and transformation, also promoting the resistance to the treatments. In HNSCC cell lines, the β2-AR selective inhibition synergistically amplifies the cytotoxic effect of the MEK 1/2 by affecting the p38/NF-kB oncogenic pathway and contemporary reducing the NRF-2 mediated antioxidant cell response. In this study, we aimed to validate the anti-tumor effect of β2-AR blockade and the synergism with MEK/ERK and EGFR pathway inhibition in a pre-clinical orthotopic mouse model of HNSCC. Interestingly, we found a strong β2-ARs expression in the tumors that were significantly reduced after prolonged treatment with β2-Ars inhibitor (ICI) and EGFR mAb Cetuximab (CTX) in combination. The β2-ARs down-regulation correlated in mice with a significant tumor growth delay, together with the MAPK signaling switch-off caused by the blockade of the MEK/ERK phosphorylation. We also demonstrated that the administration of ICI and CTX in combination unbalanced the cell ROS homeostasis by blocking the NRF-2 nuclear translocation with the relative down-regulation of the antioxidant enzyme expression. Our findings highlighted for the first time, in a pre-clinical in vivo model, the efficacy of the β2-ARs inhibition in the treatment of the HNSCC, remarkably in combination with CTX, which is the standard of care for unresectable HNSCC.© 2023. The Author(s).