School of Medicine, Tsinghua University, Beijing, China; Division of Experimental Pathology, Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
Division of Experimental Pathology, Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
Gastroenterology. 2022 Aug;163(2):449-465. doi: 10.1053/j.gastro.2022.05.007. Epub 2022 May 10.
BACKGROUND & AIMS: Intrahepatic cholangiocarcinoma (ICC) is a devastating liver cancer with extremely high intra- and inter-tumoral molecular heterogeneity, partly due to its diverse cellular origins. We investigated clinical relevance and the molecular mechanisms underlying hepatocyte (HC)-driven ICC development.
Expression of ICC driver genes in human diseased livers at risk for ICC development were examined. The sleeping beauty and hydrodynamic tail vein injection based Akt-NICD/YAP1 ICC model was used to investigate pathogenetic roles of SRY-box transcription factor 9 (SOX9) and yes-associated protein 1 (YAP1) in HC-driven ICC. We identified DNA methyltransferase 1 (DNMT1) as a YAP1 target, which was validated by loss- and gain-of-function studies, and its mechanism addressed by chromatin immunoprecipitation sequencing.
Co-expression of AKT and Notch intracellular domain (NICD)/YAP1 in HC yielded ICC that represents 13% to 29% of clinical ICC. NICD independently regulates SOX9 and YAP1 and deletion of either, significantly delays ICC development. Yap1 or TEAD inhibition, but not Sox9 deletion, impairs HC-to-biliary epithelial cell (BEC) reprogramming. DNMT1 was discovered as a novel downstream effector of YAP1-TEAD complex that directs HC-to-BEC/ICC fate switch through the repression of HC-specific genes regulated by master regulators for HC differentiation, including hepatocyte nuclear factor 4 alpha, hepatocyte nuclear factor 1 alpha, and CCAAT/enhancer-binding protein alpha/beta. DNMT1 loss prevented NOTCH/YAP1-dependent HC-driven cholangiocarcinogenesis, and DNMT1 re-expression restored ICC development following TEAD repression. Co-expression of DNMT1 with AKT was sufficient to induce tumor development including ICC. DNMT1 was detected in a subset of HCs and dysplastic BECs in cholestatic human livers prone to ICC development.
We identified a novel NOTCH-YAP1/TEAD-DNMT1 axis essential for HC-to-BEC/ICC conversion, which may be relevant in cholestasis-to-ICC pathogenesis in the clinic.
肝内胆管癌（ICC）是一种破坏性很强的肝癌，其肿瘤内和肿瘤间的分子异质性极高，部分原因是其具有多种细胞起源。我们研究了驱动 HCC 发生 ICC 的临床相关性和分子机制。
检测了有 ICC 发病风险的人类病变肝脏中 ICC 驱动基因的表达。采用基于睡美人转座子和水力尾静脉注射的 Akt-NICD/YAP1 ICC 模型，研究了 SRY 盒转录因子 9（SOX9）和 Yes 相关蛋白 1（YAP1）在 HCC 驱动 ICC 中的发病机制作用。我们确定 DNA 甲基转移酶 1（DNMT1）是 YAP1 的靶点，通过缺失和获得功能研究进行了验证，并通过染色质免疫沉淀测序研究了其机制。
在 HCC 中共同表达 AKT 和 Notch 细胞内结构域（NICD）/YAP1 可产生占临床 ICC 的 13%至 29%的 ICC。NICD 独立调节 SOX9 和 YAP1，缺失任何一个都可显著延迟 ICC 的发生。抑制 yap1 或 TEAD，但不是缺失 Sox9，可损害 HCC 向胆管上皮细胞（BEC）的重编程。发现 DNA 甲基转移酶 1（DNMT1）是 YAP1-TEAD 复合物的一个新下游效应子，它通过抑制受 HC 分化的主调控因子调节的 HC 特异性基因，从而指导 HC 向 BEC/ICC 命运转换，这些主调控因子包括肝细胞核因子 4 阿尔法、肝细胞核因子 1 阿尔法和 CCAAT/增强子结合蛋白α/β。DNMT1 的缺失可防止 NOTCH/YAP1 依赖性 HCC 驱动的胆管癌发生，TEAD 抑制后 DNMT1 的重新表达可恢复 ICC 的发生。DNMT1 与 AKT 的共同表达足以诱导肿瘤的发生，包括 ICC。在易发生 ICC 发展的胆淤积性人类肝脏中，可在一小部分 HCC 和发育不良的 BEC 中检测到 DNMT1。
我们确定了一个新的 NOTCH-YAP1/TEAD-DNMT1 轴，它对 HCC 向 BEC/ICC 转化至关重要，这可能与临床中的胆淤积症向 ICC 发病机制有关。
