Modeling Hepatoblastoma: Identification of Distinct Tumor Cell Populations and Key Genetic Mechanisms through Single Cell Sequencing

Hepatoblastoma (HB) is the most common primary liver malignancy of childhood. However, molecular investigations of the disease are limited and effective treatment options are lacking. The use of patient derived xenografts (PDX) to study biology and treatment strategies of HB has proven to be a useful tool. There is currently a knowledge gap in the investigation of key driver cells of HB in PDX models. Key driving pathways of HB tumor including WNT, AP-1, Hedgehog, Notch and MAPK pathways and genes such as GPC3, DLK1 and HMGA2 have been identified in primary HB tumor and PDX as integral players in HB tumor growth. Cell clusters have been defined with distinct roles in tumor development. Cell populations with initiating, angiogenic (endothelial), maintenance, and progression signatures have been identified in one HB patient tumor and corresponding PDX tumor. Critical pathways combined with identification of distinct cell populations within HB tumor will allow for investigation of novel treatment strategies in vitro and in vivo. Overall design: To examine HB pathways and define cell populations in a heterotopic PDX model, we implant patient source tumor into the intrascapular fat pad of female NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice. PDX tumor was compared to background liver and primary HB tumor and evaluated using single cell RNA sequencing (scRNAseq). 26,886 cells across 3 samples were collected after preprocessing and quality control.