Guo Jun, Shi Xiabing, Sun Yan, Long Ruitao, Wu Hua, Ye Feng, Xu Chuanrui
Department of Pharmacy, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Br J Cancer. 2025 Oct 24. doi: 10.1038/s41416-025-03234-8.
Intrahepatic cholangiocarcinoma (ICC) is the second most prevalent type of primary liver cancer and lacks effective targeted therapy. Previously, we reported that B cell-specific Moloney murine leukaemia virus integration site 1 (Bmi1) drives the formation and development of ICC independent of Ink4A/Arf; however, the underlying mechanism remains unclear. Here, we report that hepatic leukaemia factor (HLF) acts as a tumour-suppressor gene in ICC and Bmi1 represses HLF to drive ICC initiation and progression.
RNA sequencing was performed to find the downstream target of Bmi1 in ICC. Bioinformatic analysis and molecular biological techniques were used to examine the expression of Bmi1 and HLF in ICC. Effects of HLF silence or overexpression by lentivirus on cell proliferation or development were evaluated in human ICC cells, xenograft and primary ICC mouse models, respectively. The luciferase reporter assay was used to identify that Bmi1 regulates HLF.
In ICC, HLF expression levels were inversely correlated with Bmi1. Overexpression of HLF inhibited the growth of ICC both in vitro and in vivo, whereas HLF knockout promoted ICC development in ICC mouse models. Importantly, HLF repression reversed the inhibitory effects of Bmi1 knockdown on cell survival, proliferation and colony formation. Luciferase reporter assay results indicated that Bmi1 represses HLF by directly binding to its promoter.
These findings revealed the molecular mechanism through which Bmi1 promotes ICC formation and development and uncovered the role of HLF as a tumour suppressor in ICC.
肝内胆管癌（ICC）是第二常见的原发性肝癌类型，且缺乏有效的靶向治疗方法。之前，我们报道过B细胞特异性莫洛尼鼠白血病病毒整合位点1（Bmi1）在不依赖Ink4A/Arf的情况下驱动ICC的形成和发展；然而，其潜在机制仍不清楚。在此，我们报道肝白血病因子（HLF）在ICC中作为一种肿瘤抑制基因发挥作用，且Bmi1通过抑制HLF来驱动ICC的起始和进展。
进行RNA测序以寻找ICC中Bmi1的下游靶点。运用生物信息学分析和分子生物学技术检测ICC中Bmi1和HLF的表达情况。分别在人ICC细胞、异种移植和原发性ICC小鼠模型中评估慢病毒介导的HLF沉默或过表达对细胞增殖或发育的影响。采用荧光素酶报告基因检测法来确定Bmi1对HLF的调控作用。
在ICC中，HLF的表达水平与Bmi1呈负相关。HLF的过表达在体外和体内均抑制了ICC的生长，而在ICC小鼠模型中HLF基因敲除则促进了ICC的发展。重要的是，HLF的抑制作用逆转了Bmi1敲低对细胞存活、增殖和集落形成的抑制作用。荧光素酶报告基因检测结果表明，Bmi1通过直接结合HLF的启动子来抑制HLF。
这些发现揭示了Bmi1促进ICC形成和发展的分子机制，并揭示了HLF作为ICC中肿瘤抑制因子的作用。
