Abstract
BACKGROUND & AIMS: Liver cancer, the third leading cause of cancer-related mortality worldwide, has two main subtypes: hepatocellular carcinoma (HCC), accounting the majority of the cases, and cholangiocarcinoma (CAA). Notch pathway primarily regulates the intrahepatic development of bile ducts, which are lined with cholangiocytes, but it can also be upregulated in 1/3 of HCCs. To better understand the role of NOTCH1 in HCC, we developed a novel mouse model driven by activated Notch1 intracellular domain (NICD1) and MYC overexpression in hepatocytes. METHODS: Using the hydrodynamic tail-vein injection method for establishing primary liver tumors, we generated a novel murine model of liver cancer harboring MYC overexpression and NOTCH1 activation. We characterized this model histopathologically as well as transcriptomically, utilizing both bulk and single cell RNA-sequencing. We also performed functional experiments using monoclonal antibodies. RESULTS: MYC;NICD1 tumors displayed a combined HCC-CCA phenotype with temporal plasticity. At early time-points, histology was predominantly "cholangiocellular", which then progressed to mainly "hepatocellular". The "hepatocellular" component was enriched in mesenchymal genes and gave rise to lung metastasis. Metastatic cells were enriched in the TGFB and VEGF pathways and their inhibition significantly reduced the metastatic burden. CONCLUSIONS: Our novel mouse model uncovered NOTCH1 as a driver of temporal plasticity and metastasis in HCC, the latter of which is, in part, mediated by angiogenesis and TGFß pathways. IMPACT AND IMPLICATIONS: This study develops a novel murine model of NOTCH1-driven liver cancer, an understudied oncogene in HCC. Using this model, we show that NOTCH1 drives plasticity in HCC and metastasis to the lungs that can be therapeutically targeted through inhibition of VEGF and TGFß pathways. HIGHLIGHTS: NOTCH1 activation in combination with MYC overexpression drives combined HCC-CCA.NOTCH1 activation in hepatocytes drives temporal plasticity.NOTCH1 activation drives metastasis of HCC cells to the lungs, but not of CCA cells.Angiogenesis and TGFß pathways mediate NOTCH1-induced lung metastasis.