Development Of Pre-Clinical Murine Models For Fibrolamellar Hepatocellular Carcinoma

Fibrolamellar hepatocellular carcinoma(FLC) is a rare form of cancer that affects primarily adolescentsand young adults. FLC tumors are typically associated with an intrachromosomal deletion resulting in expression of a fusion protein between the chaperone DNAJ1B and the protein kinase PKA. FLC ischallenging to study because of its rarity and limited pre-clinical models. Here, we developed a novel transgenic mouse model of FLC. In this model, DNAJ1B-PKA expression in the liver of mouse embryos results in perinatal lethalityassociated with liver developmental defects, while DNAJ1B-PKA expression in the liver of adult mice initiates tumors resembling FLC at low penetrance. Some of these tumors can be serially propagated in 3D cultures and in allografts, including in syngeneic hosts. One such model shows growth inhibition upon treatment with the CDK4/6 inhibitor palbociclib. New pre-clinical models of FLC will provide novel insights into the biology of this rare cancerand may help identify novel therapeutic strategies. Overall design: We generated transgenic mice by inserting a DNAJB1-PRKACA-GFP cDNA into the Rosa26 locus. Upon Cre-mediated recombination and self-cleaving of the fusion protein, this construct allows expression of the DNAJB1-PKA fusion found in human FLC and the GFP reporter. We crossed Rosa26 LSL-DNAJB1-PKA-GFP mice to Alb-Cre mice where the Cre recombinase is expressed under the control of the Albumin promoter and is turned on at mid-gestation in the liver. We performed RNA sequencing (RNA-seq) from livers dissected from control and transgenic embryos at embryonic day 18.5 (E18.5) (n=5 for control and n=4 for overexpression). To generate new models of Fibrolamellar hepatocellular carcinoma (FLC), we performed allograft experiments of these models into mice and treated with the CDK4/6 inhibitor palbociclib or control injections. We then performed gene expression profiling analysis and RNA-seq of PBS and palbociclib tumor samples (n=5 from each treatment group).