Heterogeneity Among Liver Cancer--A Hurdle to Optimizing Therapy

Generation of in situ CRISPR-mediated primary and metastatic cancer from monkey liver

Non-human primates (NHPs) represent the most valuable animals for drug discovery. However, the current main challenge remains that the NHP has not yet been used to develop an efficient translational medicine platform simulating human diseases, such as cancer. This study generated an in situ gene-editing approach to induce efficient loss-of-function mutations of Pten and p53 genes for rapid modeling primary and metastatic liver tumors using the CRISPR/Cas9 in the adult cynomolgus monkey. Under ultrasound guidance, the CRISPR/Cas9 was injected into the cynomolgus monkey liver through the intrahepatic portal vein. The results showed that the ultrasound-guided CRISPR/Cas9 resulted in indels of the Pten and p53 genes in seven out of eight monkeys. The best mutation efficiencies for Pten and p53 were up to 74.71% and 74.68%, respectively. Furthermore, the morbidity of primary and extensively metastatic (lung, spleen, lymph nodes) hepatoma in CRISPR-treated monkeys was 87.5%. The ultrasound-guided CRISPR system could have great potential to successfully pursue the desired target genes, thereby reducing possible side effects associated with hitting non-specific off-target genes, and significantly increasing more efficiency as well as higher specificity of in situ gene editing in vivo, which holds promise as a powerful, yet feasible tool, to edit disease genes to build corresponding human disease models in adult NHPs and to greatly accelerate the discovery of new drugs and save economic costs.

Initiation of aberrant DNA methylation patterns and heterogeneity in precancerous lesions of human hepatocellular cancer

While intratumor heterogeneity contributes to disease progression, metastasis, and resistance to chemotherapy, it also provides a route to understanding the evolution and drivers of disease. Defects in epigenetic landscapes are intimately linked to pathogenesis of a variety of human diseases, with epigenetic deregulation promoting tumorigenesis. Understanding epigenetic heterogeneity is crucial in hepatocellular carcinoma (HCC), where epigenetic alterations are frequent, early, and pathogenic events. We determined genome-wide DNA methylation and copy number variation leveraging the Infinium 450K in a series of regenerative nodules from within single patient livers. Bioinformatics strategies were used to ascertain within-patient heterogeneity, link epigenetic changes to clinical features, and determine their relevance to disease pathogenesis. Our data demonstrate that DNA methylation and copy number alterations evolve during the pre-neoplastic phase of HCC and independently segregate regenerative nodules into distinct clusters. Regenerative nodules with a high frequency of epigenetic changes have significantly lower copy number variation, suggesting that individual nodules have differential enrichment of epigenetic and genetic components, with both contributing to disease progression. Regenerative nodules were scored based on 'epigenetic progression' with higher scores associated with increased proliferation measured by Ki67 staining. Early events observed in epigenetically 'aggressive' nodules are enriched for genes involved in liver cancer. Our study demonstrates that marked epigenetic and genetic heterogeneity exists in early pre-neoplastic liver tissue within individual patients, emphasizing the potential contributions of each mechanism to driving liver disease progression, and it unveils strategies for identifying epigenetic drivers of hepatocellular carcinoma.