炎症诱导肝前体细胞向肝癌干细胞转化的机制及临床相关研究

Liver cancer is one of the most common malignant tumor in the world. Millions of new cases were diagnosed each year, more than 50% of which occurred in China. Recurrence, metastasis and chemo resistance are the main bottleneck issues in the treatment of liver cancer, making further study of the pathogenesis and the exploration of new therapeutic strategies particularly urgent. Liver cancer stem cells (LCSCs) is the root cause of liver cancer recurrence and drug resistance, but how LCSC evolved is not clear at present. To explore the underlying mechanism, we used DEN-induced rat hepatocarcinogenesis model to mimic chronic inflammation-induced liver cancer formation in patients and found that massively expanded liver hepatic progenitor cells (LPC) could be transformed into LCSC. Macrophages and inflammatory cytokine TNF alpha may play important role in this process. In this project, using progenitor cell lineage tracing mice, we plan to further define the role of chronic inflammation in LPC conversion to LCSC. Moreover, we will use a co-culturing system of macrophages and LPC as well as long-term stimulation model of LPC upon inflammatory factor to further explore the underlying mechanism. Finally, we will verify the above finding using LPC-derived liver cancer samples from patients, which were selected from the patient tissue bank in our hospital. In all, this project aims to clarify clinical features of LPC-initiated HCC, and explore the individualized therapeutic strategy for this subset of liver cancers.

肝癌是目前世界上最常见的恶性肿瘤之一，我国的肝癌病人约占全球的一半左右。肝癌对常规化疗很不敏感，术后复发率极高，因此深入研究肝癌的发病机制并探寻新的治疗策略尤为迫切。肝癌干细胞（LCSC）是肝癌发生发展和复发耐药的根源，但LCSC产生的机制目前并不清楚。前期我们利用大鼠DEN诱癌模型模拟病人肝脏炎癌转化过程发现，伴随肝脏慢性炎症肝前体细胞（LPC）明显扩增并可能向LCSC转化，在这一过程中巨噬细胞和炎症因子TNF-α可能发挥重要作用。本项目拟利用前体细胞谱系追踪小鼠的肝癌发生模型，进一步明确慢性炎症在LPC向LCSC转化中的作用；再利用巨噬细胞与LPC共培养和炎症因子长期刺激的LPC模型，系统研究慢性炎症诱导LPC向LCSC转化的分子机制；最后从大规模病人样本中筛选LPC来源的肝癌对上述机制进行验证，结合临床病理及预后信息，阐明LPC来源肝癌的临床特征并探索个性化治疗策略。

肝癌的异质性和层次结构支持着肝癌干细胞的理论。然而，慢性肝炎症与肝癌干细胞生成之间的关系尚不清楚。本研究观察到二乙基亚硝胺处理后的肝硬化大鼠肝脏中炎症加重与肝前体细胞增殖密切相关。从肝硬化大鼠中分离的肝前体细胞引发NOD/SCID小鼠皮下形成肝癌，提示肝前体细胞向肝癌干细胞恶性转化。有趣的是，在体内消除Kupffer细胞会减弱肝前体细胞向肝癌干细胞的恶性转化，并抑制CK19+OV6+肝癌肿瘤的发生。相反，与巨噬细胞共培养的肝前体细胞表现出增强的肝癌干细胞特性。我们进一步证明巨噬细胞分泌的TNF-α通过解除泛素D和检查点激酶2触发肝前体细胞的染色体不稳定性，并通过TNFR1/Src/STAT3信号通路增强肝前体细胞的自我更新，协同促进肝前体细胞向肝癌干细胞的转化。临床研究显示CK19+OV6+肝癌患者预后较差，但对索拉非尼治疗反应较好。总之，我们的研究结果不仅阐明了炎症介导的肝癌干细胞形成的细胞和分子机制，而且为肝癌的个体化治疗提供了一种新的分子分类方法。