Hepatocyte-derived intrahepatic cholangiocarcinoma requires Yap and Sox9: A clinical and preclinical analysis.

Abstract

582 Background: Intrahepatic cholangiocarcinoma (ICC) is a liver tumor of increasing incidence and devastating prognosis. WGS and WES have identified numerous molecular pathways and fusions in ICC. Recent studies have also suggested hepatocyte as a cell source in a subset of ICCs, especially those associated with chronic liver insult such as non-alcoholic steatohepatitis (NASH) or primary sclerosing cholangitis (PSC). Methods: Since co-expression of myristoylated AKT (myrAKT) & Notch intracellular domain (NICD) in hepatocytes using sleeping beauty transposon/transposase-based hydrodynamic tail vein injection (SB-HTVI) lead to ICC, we initiated a comprehensive analysis of mechanism of ICC development in patients and in this preclinical model. Results: Over 90% of CC samples exhibited high levels of nuclear SOX9 & YAP, in addition to a significant positivity for pAKT in ICCs as compared to extrahepatic CC. We also identified upregulation of p-AKT, SOX9 & YAP in hepatocytes of patients with PSC and NASH. This was also seen in many murine models of cholestatic injury and NASH. While co-expression of myrAKT+NICD led to hepatocyte-derived ICC, conditional deletion of either Yap or Sox9 significantly delayed and almost completely abrogated ICC development. While Yap deletion impaired the initial HC-to-BEC fate conversion, Sox9 elimination had no such effect on reprograming. Interestingly, following deletion of either Yap or Sox9 we observed a few AKT/NICD-driven ICC tumors expressing either Sox9 or Yap but not both. This also occurred in a small subset of human CC tumors which may be Sox9+Yap- (4%) or Sox9-Yap+ (3.7%), showing that deletion of Yap or Sox9 is not sufficient to completely abrogate ICC development. We finally demonstrated that conditional deletion of both Yap & Sox9 completely blocked development of ICC tumors in the myrAKT+NICD model. Conclusions: Thus, we show that cholestatic injury or NASH in humans and mice induces hepatocyte-to-cholangiocyte reprograming to increase the risk of ICC development. We also provide evidence for critical but distinct roles of Yap and Sox9 in ICC development and demonstrate the therapeutic potential of targeting these factors for treatment of subsets of ICC.