Table_1_The Role of Akt in Acquired Cetuximab Resistant Head and Neck Squamous Cell Carcinoma: An In Vitro Study on a Novel Combination Strategy.docx

The epidermal growth factor receptor (EGFR) is a therapeutic target in head and neck squamous cell carcinoma (HNSCC). Resistance to EGFR-targeted therapies, such as cetuximab, poses a challenging problem. This study aims to characterize acquired cetuximab resistance mechanisms in HNSCC cell lines by protein phosphorylation profiling. Through this, promising combination treatments can be identified to possibly overcome acquired cetuximab resistance in HNSCC. Protein phosphorylation profiling showed increased phosphorylation of Akt1/2/3 after cetuximab treatment in acquired cetuximab resistant cells compared to cetuximab sensitive cells, which was confirmed by western blotting. Based on this protein phosphorylation profile, a novel combination treatment with cetuximab and the Akt1/2/3 inhibitor MK2206 was designed. Synergy between cetuximab and MK2206 was observed in two cetuximab sensitive HNSCC cell lines and one acquired cetuximab resistant variant in simultaneous treatment schedules. In conclusion, this study demonstrates that increased Akt1/2/3 phosphorylation seems to be characteristic for acquired cetuximab resistance in HNSCC cell lines. Our results also show an additive to synergistic interaction between cetuximab and MK2206 in simultaneous treatment schedules. These data support the hypothesis that the combination of cetuximab with PI3K/Akt pathway inhibition might be a promising novel therapeutic strategy to overcome acquired cetuximab resistance in HNSCC patients.

表皮生长因子受体（epidermal growth factor receptor, EGFR）是头颈部鳞状细胞癌（head and neck squamous cell carcinoma, HNSCC）的治疗靶点。针对EGFR的靶向治疗药物如西妥昔单抗（cetuximab）的耐药问题已成为该领域亟待解决的临床难题。本研究旨在通过蛋白质磷酸化谱（protein phosphorylation profiling）分析，阐明头颈部鳞状细胞癌耐药细胞系中西妥昔单抗获得性耐药的分子机制，以期筛选出可有效逆转该类获得性耐药的联合治疗方案。相较于西妥昔单抗敏感细胞系，获得性耐药细胞在经西妥昔单抗处理后，其Akt1/2/3的磷酸化水平显著升高，该结果已通过蛋白质印迹（western blotting）得到验证。基于上述蛋白质磷酸化谱特征，本研究设计了西妥昔单抗与Akt1/2/3抑制剂MK2206的新型联合治疗方案。在同步给药方案下，该联合疗法在两株西妥昔单抗敏感型头颈部鳞状细胞癌细胞系以及一株获得性耐药细胞系中均观测到协同抗肿瘤效应。综上，本研究证实Akt1/2/3磷酸化水平升高可作为头颈部鳞状细胞癌细胞系西妥昔单抗获得性耐药的特征性分子标志；研究结果同时表明，西妥昔单抗与MK2206在同步给药方案下可产生相加至协同的抗肿瘤相互作用。上述数据支持以下假说：西妥昔单抗联合PI3K/Akt通路抑制剂有望成为逆转头颈部鳞状细胞癌患者西妥昔单抗获得性耐药的新型潜在治疗策略。