活化的星状细胞通过诱导播散肝癌细胞发生间质-上皮转换促进肝癌肝内转移的机制研究

Intrahepatic recurrence is the main form of the post-operative recurrence of hepatocellular carcinoma (HCC), suggesting that the liver is the most appropriate "soil" suitable for the metastasis of hepatoma cells. Epithelial-mesenchymal transition (EMT) conferred the ability of tumor to distant metastasis, but the disseminated tumor cells (DTCs) were latent in the target organ. DTCs need to regain the epithelial cell-like phenotype, that is, they may reverse the process of EMT via a "mesenchymal-epithelial transition (MET) "to further grow into the clinical macrometastases. Previously, we found that in the tetrachloromethane pretreated nude mice, abundant hepatic stellate cells were activated, the expression of periostin was significantly increased; after injection of hepatoma cells into the spleen, more metastasis foci were observed in the pretreated group, compared with the control group. We speculated that the activated stellate cells and secreted periostin involved in the transformation of the liver microenvironment, contributing to the pre-meatastatic niche for HCC metastasis. In this project, we proposed to further study: (1) MET was the key process of the disseminated hepatoma cells growed into the macrometastases; (2) unveiled the mechanism how activated hepatic stellate cells induced the hepatoma cells underwent MET, especially the role of secreted periostin in regulating MET in hepatoma cells. By revealing the key mechanism and key molecules, we aimed to provide the potential intervention for the post-operative recurrence.

肝内复发是肝癌术后复发的主要形式，提示肝脏是适宜肝癌细胞转移的最适“土壤”。上皮-间质转换（EMT）赋予肿瘤远处转移的能力，但播散的肿瘤细胞在靶器官内滞留后，需要重新获得上皮细胞样表型，即发生EMT的反向过程“间质-上皮转换（MET）”才能进一步长成临床有意义的转移灶。我们发现，四氯化碳预处理裸鼠，肝脏内的星状细胞被激活，其表达的骨膜蛋白显著升高；经脾脏注射肝癌细胞后，与对照组相比，肝内出现更多的转移灶。我们推测，活化的星状细胞及其分泌的骨膜蛋白参与并改造了肝组织微环境，促进了肝癌肝内转移。本项目中，我们拟进一步研究：（1）MET转换在播散肝癌细胞进展为大体转移灶过程中的关键作用；（2）活化的星状细胞促进肝癌细胞MET过程的分子机制，特别是星状细胞来源的骨膜蛋白调节肝癌细胞MET过程的核心机制。通过揭示其中的关键机制，为肝癌术后的转移复发提供潜在的干预手段。

复发是影响肝细胞癌（以下简称“肝癌”）术后长期生存的主要原因，目前缺乏公认的预防手段。70%以上的肝癌术后复发主要集中于术后2年以内（早期复发），而癌旁的肝内组织则被认为是术后肝癌细胞肝内播撒转移的特殊靶器官，尤其是肝组织被改造为预转移微环境。阻止癌旁肝组织术后早期复发成为预防复发的关键。在本项目实施过程中，我们发现：1）不完全射频消融术后的肝组织微环境适合肿瘤细胞播散的“土壤”，肿瘤细胞通过plakoglobin发生MET转换，成长为肉眼可见的病灶，2）不完全射频消融术后残余肝癌细胞能通过发生EMT转换促进癌旁肝内组织的早期复发转移，并增强侵袭转移潜能；3）进一步通过肝癌裸鼠模型发现，残余肝癌细胞能够过表达LncRNA ASMTL-As1，其能够被外泌体包裹，利用miR-342-3p通过细胞间的NLK/YAP信号轴传递，增强肝癌细胞的侵袭转移潜能。以上这些发现为主要研究结果，已发表标注受本项目资助的SCI论文4篇。本项目揭示了肝癌术后早期癌旁肝内组织早期复发转移的作用机制，评估肝癌射频消融治疗疗效利于避免残余肝癌细胞存留及增强恶性潜能，具有一定的临床指导意义。