Tracking transcriptional changes in a species-specific manner during experimental hepatoblastoma progression in vivo. Tracking transcriptional changes in a species-specific manner during experimental hepatoblastoma progression in vivo

Hepatoblastoma is a primitive liver cancer occurring mainly in infants with defined molecular alterations driving its progression, which is difficult to model in vivo. Here we present a new animal model for hepatoblastoma on the chick chorioallantoic membrane (CAM), which recapitulates relevant features of hepatoblastoma in patients. Expression of classic tumor-associated proteins such as β-catenin, EpCAM and CK19 was maintained in acini-like organized tumors on CAM, as was synthesis of AFP, a tumor marker used for monitoring patient response. RNA sequencing revealed an unexpected molecular evolution of hepatoblastoma cells on the CAM, with significant deregulation of more than 6000 genes including more than half of all HOX genes. Bioinformatic analysis could clearly distinguish between tumor cell-expressed genes and chick host genes, thereby shedding new light on the complex interactions taking place during experimental hepatoblastoma progression. Importantly, human tumor suppressive ribosomal genes were downregulated after implantation, whereas mitochondrial genes encoding for anti-apoptotic peptides were strongly induced in vivo. Meprin-1α expression was increased during evolution of CAM tumors and confirmed by immunohistochemistry. Cisplatin, a commonly used chemotherapeutic agent for hepatoblastoma, showed significant anti-tumoral effects in this model. Our results broaden the understanding of the molecular adaptation process of human cancer cells to the microenvironment and might help to elaborate novel therapeutic concepts for the treatment of this pediatric liver tumor. Overall design: HuH6 cells and CAM mRNA profiles were generated by deep sequencing, in triplicate, using Illumina HiSeq 2500 and HiSeq 2000, respectively