Fate and functional roles of Prominin 1(+) cells in liver injury and cancer

Prominin 1 (PROM1) is one of a few clinically relevant progenitor markers in human alcoholic hepatitis (AH) and hepatocellular carcinoma (HCC), and mouse liver tumor initiating stem cell-like cells (TICs). However, the origin, fate and functions of PROM1(+) cells in AH and HCC are unknown. Here we show by genetic lineage tracing that PROM1(+) cells are derived in part from hepatocytes in AH and become tumor cells in mice with diethyl nitrosamine (DEN)-initiated, Western alcohol diet-promoted liver tumorigenesis. Our RNA sequencing analysis of mouse PROM1(+) cells, reveals transcriptomic landscapes indicative of their identities as ductular reaction progenitors (DRPs) and TICs. Indeed, single-cell RNA sequencing reveals two subpopulations of Prom1(+) Afp(–) DRPs and Prom1(+) Afp(+) TICs in the DEN-WAD model. Integrated bioinformatic analysis identifies Discodin Domain Receptor 1 (DDR1) as a uniquely upregulated and patient-relevant gene in PROM1(+) cells in AH and HCC. Translational relevance of DDR1 is supported by its marked elevation in HCC which is inversely associated with patient survival. Further, knockdown of Ddr1 suppresses the growth of TICs and TIC-derived tumor growth in mice. These results suggest the importance of PROM1(+) cells in the evolution of liver cancer and DDR1 as a potential driver of this process.