基于靶向测序和单细胞技术的肝癌分子遗传研究

Liver cancer is the second leading cause of cancer related deaths worldwide, more than half of which were from China. Hepatocellular carcinoma (HCC) is the major form of primary liver cancer. High percentage of metastasis and recurrence lead to the dismal prognosis of HCC. It’s closely associated with the fact that HCC always develop multiple lesions (MLs). However, studies about its genetic features and carcinogenesis is very limited. In this project, we propose to integrate exome sequencing, ultra-deep targeted sequencing and single cell techniques to investigate the genome of 150 MLs from 10-15 HCC cases. Cancer cell fraction analysis will be used to deduce the subclonal structure of these MLs and reconstruct the clonal evolutionary process. Then, the detailed metastatic history of these HCC cases will be portrayed. We will try to address whether there are multi-clone metastasis and metastasis to metastasis during the formation of MLs. Potential driver events leading to different types of MLs will be analyzed through comparison across patients. Integrating these analyses, we seek to unveil the genomic features of MLs, which can provide critical information for the diagnosis and treatment for HCC patients.

肝癌是世界上致死率排名第二的癌症，且超过一半的死亡病例来自中国。肝癌的主要类型为肝细胞癌。多发病灶是造成肝细胞癌预后较差和病人死亡的重要原因，但其遗传学特征和形成机制尚不清楚。本项目中，我们将综合利用外显子测序、超高深度靶向测序和单细胞技术对10-15例肝细胞癌的150个多发病灶进行深入分析。通过肿瘤突变细胞占比分析推断各个病灶的细胞亚克隆结构，重构肿瘤发展和转移过程中的亚克隆演化进程，最终精确绘制各病例多发病灶的详细转移历史。确定肝内转移是否存在多克隆转移和二次转移等关键问题。通过病人间分析确定不同类型多发病灶的转移规律和驱动事件。综合上述分析揭示肝细胞癌多发病灶的遗传学特征和癌变分子机制，为肝细胞癌的诊断和治疗提供关键信息。

原发性肝癌是世界范围内致死率第三的癌症，其主要包括肝细胞癌、肝内胆管癌和混合型肝癌三种亚型。多发病灶是造成肝癌预后较差和病人死亡的重要原因。但是，其遗传学特征和形成机制尚不清楚。本项目中，我们综合利用外显子测序、超高深度靶向测序和单细胞测序技术对三种原发性肝癌的多发病灶进行深入分析。通过肿瘤突变细胞占比分析推断各个病灶的细胞亚克隆结构，重构肿瘤发展和转移过程中的亚克隆演化进程。本项目主要取得了四项研究进展：1）通过单细胞DNA测序技术揭示肝癌单细胞层面异质性，提出基于拷贝数变异的截断-渐进的双相演化模型，发现新的肝细胞癌预后标志物CAD；2）揭示混合型肝癌多发病灶的肿瘤异质性和肝内转移的遗传学特征，揭示混合型肝癌不同表型病灶的克隆起源和表型转化现象，发现混合型肝癌的诊断和预后标志物Nestin；3）揭示肝内胆管癌多发病灶的遗传学特征，发现肝内胆管癌的异质性在多个层面均显著高于肝细胞癌，发现IDH突变亚组具有独特的基因组和免疫微环境特征；4）基于肝癌多发病灶的整合分析流程，揭示了结直肠癌淋巴结转移和肝转移的转移模式、路径和历史，该结果进一步证明了本研究思路的可行性和可推广性。综上，上述研究成果系统揭示了原发性肝癌不同亚型多发病灶的遗传学特征，重构了不同病灶的转移路径和转移历史，解释了多发病灶的克隆演化规律，发现了一系列新的肝癌诊断和预后标志物，为肝癌的精准诊疗提供了关键信息，同时本项目的成果也为探索其他癌种的转移历史与路径提供了重要参考。