NHERF1对ALK阳性NSCLC患者克唑替尼治疗耐药性的影响及机制研究

At present, lung cancer is one kind of malignant tumor with the highest morbidity and mortality all over the world. ALK fusion gene is a second new target after EGFR target in the therapy of lung cancer. Crizotinib is the first choice of targeted therapy for patients with ALK fusion gene mutation non-small cell lung cancer. Unfortunately, crizotinib has encountered primary or secondary resistance. It was found in our previous study that the activation of ALK pathway by ALK fusion mutation could induce the expression of NHERF1. However, the over-expression of NHERF1 could inhibit proliferation, migration and other functions of cancer cells, and the expression of NHERF1 in lung cancer cells with crizotinib-resistance reduced with the elevation of EGFR activation. Therefore, it is predicted that ALK infusion mutation might induce the over-expression of NHERF1, and NHERF1 could inhibit ALK and EGFR signaling pathway; while for those patients with crizotinib-resistance, the decreased feedback inhibition effects of ALK and EGFR signaling pathway is most likely due to the decreased expression of NHERF1. The new mechanism of the intracellular regulation and control of ALK signaling transduction would be revealed in present study through cellular experiments and detections of clinical samples, and would be further helpful to explain the molecular mechanisms of crizotinib-resistance.

肺癌是目前发病率和死亡率排名第一的恶性肿瘤。ALK融合基因是继EGFR后肺癌分子靶向治疗的新靶点。克唑替尼系针对该新靶点的ALK阳性非小细胞肺癌（NSCLC）患者的首选靶向治疗用药。然而，该药已出现原发或继发耐药。本课题组前期研究发现：ALK融合突变使ALK通路激活，诱导NHERF1的表达，而NHERF1的过表达反过来抑制肺癌细胞的增殖与迁移等功能，且克唑替尼耐受的肺癌细胞中NHERF1表达降低而EGFR活化升高。据此推测，ALK融合突变可诱导NHERF1过表达，而NHERF1的过表达可抑制ALK以及EGFR信号通路；NHERF1在克唑替尼耐受的肿瘤患者体内的表达可能降低，导致其对ALK以及EGFR信号通路的反馈抑制作用减弱，从而产生了耐药性。本项目将通过细胞实验及临床样本分析，阐明细胞内调控ALK信号转导的新途径，有望揭示患者对克唑替尼产生获得性耐药的分子机制。

肺癌是目前发病率和死亡率排名第一的恶性肿瘤。ALK融合基因是继EGFR后肺癌分子靶向治疗的新靶点。克唑替尼系针对该新靶点的ALK阳性非小细胞肺癌（NSCLC）患者的首选靶向治疗用药。然而，该药已出现原发或继发耐药，因此，研究细胞内ALK信号通路的调节机制有利于揭示靶向药物耐受性产生的原因，指导临床用药，并且为治疗肺癌提供新的靶点。本研究通过数据库分析及临床肿瘤样本检测，发现NHERF1在肺癌中表达量显著上调，并且ALK阳性肺腺癌患者组织中NHERF1表达量显著高于ALK阴性肺腺癌患者；ALK的激动剂Heparin诱导ALK阳性肺腺癌细胞系H3122细胞内ALK通路激活，进而促进了NHERF1的表达；而NHERF1的过表达抑制细胞内ALK的磷酸化激活并抑制其下游信号蛋白AKT和ERK的激活，进而抑制了H3122细胞的增殖能力，并且降低细胞对克唑替尼的耐受性；细胞内NHERF1与ALK相互作用，ALK的激动剂Heparin促进NHERF1与ALK的相互作用，NHERF1可能通过相互作用抑制ALK的磷酸化激活，进而影响了细胞对克唑替尼的耐受性；另外，过表达NHERF1显著抑制肺腺癌细胞的上皮间质转化，NHERF1也可能通过调节细胞的上皮间质转化影响细胞对靶向药物的耐受性。因此，克唑替尼的长期使用可能降低患者体内NHERF1的表达， NHERF1的低表达对ALK信号通路的反馈抑制作用减弱，从而产生了耐药性。本项目研究结果有助于指导临床用药，并为ALK阳性非小细胞肺癌患者的治疗提供新的思路和靶点。