肝癌干细胞在营养应激下的代谢重编程及调控机制研究

Due to inadequate blood supply in the fast-growing solid tumors, cancer cells are chronically exposed to stressful conditions with crucial nutrients and oxygen insufficiency. We previously observed that the percentage of hepatic cancer stem cells (CSCs) was markedly elevated under metabolic stresses, indicating that they are more capable of resisting these unfavorable conditions. Here we are planning to examine the self-renewal capability of CSCs under various nutritional deficiencies. The reprogramming of metabolism in CSCs will be determined using metabolic labeling approaches. This may also aid in determination of the critical metabolic pathways and key regulators responsible for the adaptation of CSCs to nutrient deficiency. To explore the underlying mechanisms of metabolic alternations, we will investigate the impact of critical signaling pathways in CSCs such as Wnt/β-catenin and IL6/Stat3 on metabolic reprogramming during nutrient deficiency. Based this, we will be able to identify effective small molecules that could prevent adaptation of CSCs to nutrient deficiency. To determine the in vivo effects of metabolic stress on CSCs, we are going to establish animal models of HCC and treat them with artery embolism chemotherapy (TACE) or anti-angiogenic drug Sorafenib, both of which are used clinically and can lead to nutrients insufficiency in hepatic tumors. Moreover, we will determine whether the combination with small molecules targeting metabolic adaptation in CSCs is able to enhance the antitumor effects TACE or Sorafenib in vivo. In short, our study will elucidate the detailed changes and the underlying mechanisms in the metabolic adaptation of hepatic CSCs to nutritional stresses. Our results may also provide new potential anticancer strategies for the current targeted therapy toward advanced HCC.

实体肿瘤生长迅速而血供不足，经常处于营养应激状态。前期我们发现营养应激环境中肝癌干细胞的比例明显增加，这提示肝癌干细胞具有更强的抵抗营养应激的能力。本项目以肝癌干细胞在不同营养物质缺陷条件下的自我更新能力为切入点，结合代谢标记技术，拟探明肝癌干细胞在营养应激下的代谢重编程方式，确定关键的代谢通路和节点，探讨重要干细胞信号通路对代谢重编程的调控作用和机制，并筛选有效的小分子干预探针。在此基础上，在肝癌动物模型上应用动脉栓塞化疗（TACE）和分子靶向药索拉非尼等在临床上可引起营养应激的治疗手段，观察体内治疗引起的营养应激对相关代谢通路的影响，并联合前述靶向肝癌干细胞代谢重编程的小分子探针，观察能否增强抗肿瘤效果。本研究通过深化对肝癌干细胞代谢重编程机理的认识，期望为肝癌的治疗选择提供新的思路和策略，进一步提高肝癌的治疗效果。

实体肿瘤生长迅速而血供不足，经常处于营养应激状态。尽管研究领域内共识在营养应激状态下的重新编程新陈代谢是恶性肿瘤的一个标志，并在癌症的发展中发挥重要作用，但代谢变化与分级癌细胞的联系仍然是较弱的，特别是与癌症干细胞样细胞。本项目以肝癌细胞在不同营养物质缺陷条件下的自我更新能力为切入点，结合代谢标记技术，通过体内外模型拟探明肝癌细胞在营养应激下的代谢重编程方式，确定关键的代谢通路和节点，探讨重要细胞信号通路对代谢重编程的调控作用和机制，并筛选有效的小分子进行治疗干预。我们发现肝脏肿瘤起始细胞 (T-ICs)在限制葡萄糖条件下优先存活。尤其CD133 + T-ICs亚群通过优先表达葡萄糖转运蛋白（GLUT1和GLUT3）在葡萄糖摄取的竞争中获得成功；当抑制G LUT1或GLUT3时，则失去了生存优势，并且肝脏T-ICs的致瘤潜力也受到抑制。进一步的研究显示，IL-6的刺激会上调GLUT1和GLUT3在CD133 + T-ICs中的表达，特别是在低糖条件下。而且抑制葡萄糖的摄取使得肝脏T-ICs索拉非尼治疗更加敏感，并增强肝癌体内治疗效果。我们的研究结果表明阻断IL-6 / STAT3介导的优先葡萄糖摄取可能成为肝细胞癌（HCC）进展期的新型治疗靶点，由此为肝癌治疗的选择方案与治疗效果的提高提供新的思路和策略。同时，我们研究了在营养应激的微环境下脂质合成代谢途径对肝癌细胞存活的影响以及其具体的调控机制，即ACCα在正常培养条件下可促进脂质合成并储存，而在减糖应激状态下可促进脂质氧化分解供能利用细胞存活。鉴于ACCα在肝癌细胞脂质代谢和维持应激条件下细胞存活中的重要作用，我们推测靶向针对ACCα表达或者联合应用脂质合成抑制剂可能会增强肝癌细胞对介入治疗的敏感性，从脂质代谢途径为肝癌的个性化治疗提供了新的分子靶点和研究思路。此外，在本课题肝癌干细胞代谢调控基础上，通过发现肝脏干细胞调控的关键代谢调控机制，解决了人类肝细胞体外培养和应用难题，为细胞治疗和药物筛选提供了关键的技术基础，进一步拓展了本课题的研究内容，整体深化了干细胞代谢重编程机理的认识，期望为各类肝脏疾病的治疗提供坚实的研究基础。