同时靶向线粒体氧化磷酸化和糖酵解能量代谢通路增强肺鳞癌化学预防作用的机理研究

Lung cancer is the leading cause of cancer death in the world. Cigarette smoking is the number one risk factor for lung cancer, especially for lung squamous cell carcinoma. Preventing lung cancer development in at-risk populations is an important strategy to reduce mortality efficiently. Increasing evidence implicates metabolic changes including reliance on aerobic glycolysis as well as changes in mitochondrial oxidative phosphorylation (OXPHOS) as tumor specific hallmarks which play a vital role in initiating and maintaining the tumor phenotype. Targeting these tumor specific changes could prove highly effective, with minimal toxicity to bystander tissues, making this strategy particularly attractive and novel in the realm of cancer chemoprevention. However, inhibition of glycolysis in tumors leads to the activation of mitochondrial OXPHOS pathway to compensate the loss of ATP generation, which ultimately may contribute to the limited efficacy from glycolysis inhibitors. We have recently demonstrated potent efficacy of natural compound honokiol in a NTCU-induced lung squamous cell carcinoma model. Mechanism of action suggests that the efficacy of honokiol is primarily mediated by targeting mitochondrial OXPHOS. We therefore hypothesize that dual targeting both glycolysis and mitochondrial OXPHOS will have synergistic effect in preventing the development of lung squamous cell carcinoma. We will use our NTCU-induced lung squamous cell carcinoma mouse model to determine the chemopreventive efficacy of a combination of honokiol and a glycolysis inhibitor 3-bromopyruvate inhibiting both glycolysis and mitochondrial OXPHOS pathway. Meantime, we will reveal the underneath mechanisms by using isotope tracer-based LC-MS/MS technique, pharmacokinetics study and shRNA etc. This proposal is timely and significant, results from this proposal will provide a solid foundation for clinical trials of these two promising agents and more broadly could create a new strategy of chemoprevention targeting cancer metabolism.

肺癌是致死率最高的恶性肿瘤，吸烟是导致肺癌、特别是肺鳞癌的首要因素，对高危人群进行化学预防是降低肺癌死亡率的重要策略。能量代谢变化是肿瘤发生的早期事件，研究显示抑制糖酵解对肿瘤有明显化学预防作用，能量代谢途径成为化学预防领域的新靶点。然而能量代谢通路之间存在交叉和代偿，单一抑制肿瘤糖酵解，却激发氧化磷酸化代偿性升高，以致效果有限。申请人前期研究建立高度拟合人肺鳞癌发生的小鼠鳞癌模型，发现和厚朴酚是有效的鳞癌化学预防剂，可靶向线粒体氧化磷酸化，降低肿瘤能量水平。据此推测同时抑制线粒体氧化磷酸化和糖酵解两条能量代谢通路可显著增强肺鳞癌的化学预防效果。本课题将利用自行建立的小鼠肺鳞癌化学预防模型，采用药物纳米雾化吸入给药、同位素示踪、免疫组化及RNA干扰等方法，对靶向线粒体氧化磷酸化和糖酵解两条能量代谢通路的药物化学预防效果和机制进行系统研究，建立靶向肿瘤能量代谢的肺癌化学预防新策略。

肺癌是当今世界发病率和死亡率最高的恶性肿瘤，预计到2025年，我国肺癌患者将达到100万。近来随着早期诊断和治疗技术的快速发展，结直肠癌、前列腺癌、乳腺癌、肝癌等恶性疾病的疗效有了一定提高，但对于肺癌的治疗依然没有取得很好的进展。化学预防是利用天然或合成的化学物质，阻止、逆转和减缓癌症发生发展过程的策略。靶向能量代谢的肿瘤防治策略受到了广泛关注。肿瘤细胞与正常细胞最显著的差异即在于能量代谢方式不同，肿瘤细胞主要利用糖酵解产能（Warburg效应），而正常细胞主要利用线粒体氧化磷酸化产能。和厚朴酚（Honokiol）是从木兰科植物根茎提取的有效成分。3-BrPA 是己糖激酶（糖酵解途径的第一个限速酶）特异性抑制剂，它能与 HK-II活性部位-XH 基结合，使该酶的活性被抑制，从而阻断肿瘤细胞的糖酵解过程，使肿瘤细胞因能量供应缺乏而死亡。和厚朴酚可通过靶向线粒体，抑制氧化磷酸化，发挥肺鳞癌抑制作用。本研究利用honokiol联合3-BrPA对肿瘤能量代谢（氧化磷酸化和糖酵解）途径的双靶点抑制，在体内、体外模型上系统研究honokiol联合3-BrPA对肺鳞癌化学预防的协同增强效应和机制，以期建立靶向肿瘤能量代谢的肺癌化学预防新策略。