A number of unmet clinical needs confront IRs aiming to improve HCC outcomes. A large animal model with genetic, anatomic, and physiologic similarities to humans is compulsory to support the transition from preclinical models to human clinical trials. The Oncopig is a transgenic pig that develops site/cell specific tumors after adenovirus mediated Cre recombinase (AdCre) exposure induces expression of KRAS(G12D) and TP53(R167H), mutations found in >50% of human cancers. This study aimed to validate this porcine HCC model.
Porcine hepatocyte cultures from 3 Oncopigs were established via liver resection, hepatocyte isolation, and AdCre transformation. Transgene and hepatocyte specific gene expression was determined using RT-PCR. Genome-wide expression profiles were monitored via RNA-seq. Tumorigenicity was verified by injecting porcine HCC (pHCC) cells into SCID mouse livers. Autologous tumorigenesis was established by injecting pHCC cells into Oncopig SQ sites. Histologic features of pHCC cells and tumors were evaluated by H&E staining.
pHCC cells expressed transgenic KRAS(G12D) and TP53(R167H). While normal hepatocytes became apoptotic after 15 days in culture and did not produce AFP, pHCC cells remained viable after 100 passages (confirming malignancy) and secreted AFP (40-50 ng/mL). pHCC showed cellular pleomorphism with pale/granular cytoplasm and polygonal nuclei as in human HCC. pHCC RNA-seq detected transcriptional hallmarks of human, including TERT reactivation, apoptosis evasion, angiogenesis activation, altered cell cycle regulation, and Wnt signaling activation. Common master regulators of reduced gene expression were also identified across pHCC and human HCC cell lines. 9/9 (100%) SCID mouse liver injection sites resulted in tumors that recapitulated features of human HCC, including trabeculae formation, pseudoacinar patterning, and well-vascularized stroma. Autologous Oncopig injection of pHCC cells yielded a 2.7 cm tumor histologically characterized as Edmondson Steiner grade 2 HCC.
The current data confirm utility of Oncopig HCC as a clinically relevant model to investigate IR locoregional and targeted therapies of human HCC in translational studies.