阿莫地喹抑制RAS突变型非小细胞肺癌自噬的机制研究

Non-small cell lung cancers (NSCLC) are the leading cause of cancer-related death worldwide. More than 30% NSCLC are driven by oncogenic RAS mutations that are associated with poor prognosis and therapeutic resistance. Compared to other genetic alterations in NSCLC that can be treated with targeted therapies directly, oncogenic RAS mutation is still considered “undruggable” due to its lacking binding pockets as an irreversibly activated enzyme. It has been well established that RAS-driven tumors highly depend on autophagy as a cell survival mechanism. Our preliminary study has demonstrated that the antimalarial amodiaquine causes autophagy and proliferation in BRAF-mutant human melanoma cells. Our unpublished data suggest that amodiaquine forms protein adductions with a major eukaryotic translation initiating factor eIF4a, suggesting this protein complex could contribute to autophagy inhibition. Herein, I propose that amodiaquine preferentially targets RAS-driven NSCLC through inhibition of autophagy. I will fully elucidate the mechanisms of action of amodiaquine on NSCLC at cellular and molecular level, and further validate its therapeutic effects in the pre-clinical KRASLSL-G12D transgenic mouse model. This study will lay theoretical foundations for identification of novel drug targets and clinical treatment of NSCLC.

非小细胞肺癌（NSCLC）是发病率和致死率最高的肿瘤，原癌基因RAS的激活突变是NSCLC发病的主要原因之一，与肿瘤的不良预后和抗药性密切相关。由于RAS分子表面光滑无药物结合口袋，目前尚无直接靶向突变RAS的药物。自噬是RAS突变型肿瘤赖以生存的重要机制，抑制自噬也是抗肿瘤药物开发的新靶点。申请人前期研究证实，抗疟疾药物阿莫地喹可以有效抑制BRAF突变型黑色素瘤细胞的自噬和增殖。预实验发现，阿莫地喹能够与真核翻译起始因子eIF4a形成蛋白质复合物，提示阿莫地喹通过结合eIF4a抑制自噬。因此本项目提出：阿莫地喹通过阻断自噬进而特异性抑制RAS突变型NSCLC的增殖。本项目拟在分子、细胞水平及KRASG12D突变的肺腺癌小鼠模型中，探讨阿莫地喹对RAS突变型NSCLC增殖和自噬的抑制作用及其分子机制。本项目将为RAS突变型NSCLC的临床治疗和靶点药物开发提供理论依据。

肺癌是全球发病率和致死率最高的恶性肿瘤，自噬是维持细胞稳态的重要机制之一，与肿瘤的发生发展密切相关，因此通过抑制自噬抗肿瘤已成为肿瘤治疗的新思路。硬脂酰辅酶A去饱和酶1（SCD1）是不饱和脂肪酸形成的限速酶，在多种恶性肿瘤中高表达，也是自噬泡形成的必要条件。本项目研究发现阿莫地喹（Amodiaquine，AQ）能够诱导肺癌细胞中自噬泡的形成，同时引起肺癌细胞SCD1表达量的升高，因此我们探讨了AQ与SCD1的抑制剂联合对肺癌的疗效。本项目研究结果显示AQ与SCD1抑制剂A939572联合能够更好地抑制肺癌细胞的体外增殖，并诱导细胞周期阻滞在S期，但对细胞凋亡没有明显影响。动物实验结果也显示A939572和AQ联合能够显著抑制体内肺癌肿瘤的生长。进一步机制研究发现，AQ利用自身的氨基集团能够改变自噬溶酶体的酸性环境进而抑制自噬溶酶体的降解，同时AQ还能够诱导正常条件下自噬泡的形成，而后者是诱导SCD1高表达的主要原因。阻断自噬泡的形成能够降低SCD1的表达。自噬泡的形成会激活ERK1/2和NF-κB信号通路，上调SREBP2进而介导SCD1的高表达。AQ与SCD1抑制剂联合能够更有效的抑制肺癌生长，本项目的研究成果为抗疟药物AQ在癌症临床治疗上的应用提供新思路，也为肺癌的治疗和药物开发提供理论依据。