靶向Cathepsin L干预肺癌干细胞干性维持及其耐药的策略研究

Drug resistance remains the major cause of treatment failure among the lung cancer patients. Keeping stemness of lung cancer stem cells give them higher natural drug resistance to chemotherapy. Autophagy is the key of the stemness maintenance. The scientific problem of this project which focus on is the mechanism of Cathepsin L, a autophagy-lysosomal protein, acts on the stemness maintenance of lung cancer stem cells and the strategy for drug resistance. Our preliminary study found the expressions of Cathepsin L, stemness gene SOX2, survival gene Bcl-XL and ABC transporter ABCG2 were extraordinarily elevated in both drug resistant human lung cancer tissues and lung cancer stem cells. After Cathepsin L inhibition, the expression of CD133 significantly reduced, the sphere formation efficiency decreased, and eventually the drug resistance of lung cancer stem cells to cisplatin reversed. Furthermore, Cathepsin L was abnormal activated in p53 mutation type cancer cells. Building on these results, we propose to study the regulatory mechanisms of Cathepsin L on stemness maintenance of lung cancer stem cells and drug resistance through both the stemness gene signaling pathway and the survival gene signaling pathway. Our study will provide new insights into the essential roles of mutant p53 on transcriptional regulation of Cathepsin L. Thus, targeting Cathepsin L might be explored as a novel target and theoretical basis for individualized treatment of lung cancer patients.

化疗耐药是导致肺癌治疗失败的主要原因。肺癌干细胞的干性维持是肺癌耐药产生的关键，自噬在干性维持中的作用至关重要。本项目聚焦的科学问题是自噬溶酶体相关蛋白-组织蛋白酶L（Cathepsin L）对肺癌干细胞干性维持及耐药的作用机制和干预策略。前期工作及预初实验发现耐药患者肺癌组织和肺癌干细胞中，组织蛋白酶L、干性基因SOX2、生存基因Bcl-XL和耐药蛋白ABCG2均高表达；抑制组织蛋白酶L后，干细胞标志物CD133表达下调，干细胞球形成率降低，并可逆转肺癌干细胞对顺铂的耐药；此外，突变p53的肿瘤细胞中组织蛋白酶L异常活化。本项目拟以肺癌干细胞干性维持为切入点，系统研究和明晰组织蛋白酶L通过激活干性基因和生存基因途径调控肺癌干细胞干性维持及耐药的机制；揭示突变p53激活组织蛋白酶L转录调控机制及其与肺癌干细胞干性维持和耐药的关联性，探索和建立靶向干预抑制组织蛋白酶L逆转肺癌耐药的新策略。

化疗耐药是导致肿瘤治疗失败的主要原因。肺癌干细胞的干性维持是肺癌耐药产生的关键，其中非小细胞肺癌（NSCLC）约占所有肺癌的80%。我们的研究表明，组织蛋白酶Cathepsin L在NSCLC干细胞干性维持和耐药中的重要作用。与此同时，靶向干预Cathepsin L后，NSCLC干细胞对一线化疗药物的耐药指数均有显著的降低。在此基础上，揭示了突变p53对Cathepsin L的转录调控的分子机制。发现突变p53能通过诱导转录因子Egr-1调控Cathepsin L的表达，继而促进NSCLC细胞的上皮间质转化。突变p53和Egr-1协同参与对Cathepsin L的转录过程，提示p53基因状态和Cathepsin L蛋白在肺癌发生发展方面起着重要的作用。进一步利用R2基因分析和可视化平台分析，Cathepsin L与NSCLC患者化疗耐药及预后不良密切相关。同时，体内外的研究证明，去泛素化酶UCHL1的表达水平与NSCLC耐药存在正相关。UCHL1可通过上调TS的表达，促进细胞周期进展和DNA修复能力，介导NSCLC细胞增殖，参与了NSCLC耐药的过程。此外，通过干预UCHL1可促进细胞周期停滞和DNA损伤并提高耐药细胞对化疗药物敏感性。我们的发现为肺癌化疗耐药拓展了新思路，为肺癌耐药的临床治疗提供了新的策略与潜在靶点。