肺癌HER2激酶αC-β4环结构影响靶向治疗敏感性的机制研究

HER2 20号外显子插入(HER2 20ins)占HER2突变肺癌的62-90%，靶向治疗疗效有限，但机制不明。申请人前期发现，不同突变体具有不同的αC-β4环结构和激酶构象谱（J Thorac Oncol 2020），且对靶向治疗的敏感性不同（Oncologist 2019）。预实验提示，αC-β4环不同的突变体其PI3K通路及下游调控基因表达存在差异。因此，申请人提出假说：αC-β4环调控激酶变构作用，通过活化旁路途径PI3K通路，导致HER2 20ins对靶向治疗原发耐药。本项目拟通过构建 HER2 20ins突变体，分别改变αC-β4环长度与关键位点氨基酸，分析其对药物敏感性、激酶构象谱、PI3K通路活化与基因表达情况的影响，阐明αC-β4环通过调控激酶变构影响HER2 20ins靶向治疗敏感性的机制。本项目的开展将为HER2突变肺癌靶向治疗获益人群的识别及精准治疗提供理论依据。

HER2 exon 20 insertions (HER2 20ins), accounting for 62-90% of HER2-mutant lung cancers, respond poorly to most targeted therapies. However, its mechanism of primary resistance remains unknown. We previously reported that different HER2 20ins mutants harbored different kinase αC-β4 loops and kinase conformational landscapes (J Thorac Oncol 2020). Their responses to kinase inhibitors were also different (Oncologist 2019). Preliminary experiments showed that HER2 20ins mutants with different αC-β4 loops had different levels of activation and gene expression in the PI3K pathway. Based on the above findings, we hypothesize that, HER2 kinase αC-β4 loop regulates the kinase allosteric effect, which could activate PI3K pathway and mediate primary resistance to kinase inhibitors in lung cancer with HER2 20ins. To test the hypothesis, we intend to construct different HER2 20ins mutants and respectively change the length and key amino acids of their αC-β4 loops. Afterwards, we evaluate the impacts of these changes on drug sensitivity, kinase conformational landscapes, as well as the activation and gene expression levels in the PI3K pathway. Results of this study would clarify the impacts and action of mechanism of kinase αC-β4 loops on sensitivity to kinase inhibitors in lung cancer with HER2 20ins. Hopefully, the present study could elucidate the heterogeneity of HER2-mutant lung cancers, which will help identifying kinase inhibitor-responsive patients and facilitating personalized therapy in this population.