Epigenetic footprint enables molecular risk stratification of hepatoblastoma with clinical implications

Background & Aims: Hepatoblastoma (HB) is a rare disease. Nevertheless, it is the predominant pediatric liver cancer, with limited therapeutic options for patients with aggressive tumors. Herein, we aimed to uncover the mechanisms of HB pathobiology and to identify new biomarkers and therapeutic targets in a move towards precision medicine for patients with advanced HB. Methods: We performed a comprehensive genomic, transcriptomic and epigenomic characterization of 159 clinically annotated samples from 113 patients with HB, using high-throughput technologies. Results: We discovered a widespread epigenetic footprint of HB that includes hyperediting of the tumor suppressor BLCAP concomitant with a genome-wide dysregulation of RNA editing and the overexpression of mainly non-coding genes of the oncogenic 14q32 DLK1-DIO3 locus. By unsupervised analysis, we identified 2 epigenomic clusters (Epi-CA, Epi-CB) with distinct degrees of DNA hypomethylation and CpG island hypermethylation that are associated with the C1/C2/C2B transcriptomic subtypes. Based on these findings, we defined the first molecular risk stratification of HB (MRS-HB), which encompasses 3 main prognostic categories and improves the current clinical risk stratification approach. The MRS-3 category (28%), defined by strong 14q32 locus expression and Epi-CB methylation features, was characterized by CTNNB1 and NFE2L2 mutations, a progenitor-like phenotype and clinical aggressiveness. Finally, we identified choline kinase alpha as a promising therapeutic target for intermediate and high-risk HBs, as its inhibition in HB cell lines and patient-derived xenografts strongly abrogated tumor growth. Conclusions: These findings provide a detailed insight into the molecular features of HB and could be used to improve current clinical stratification approaches and to develop treatments for patients with HB. Lay summary: Hepatoblastoma is a rare childhood liver cancer that has been understudied. We have used cutting-edge technologies to expand our molecular knowledge of this cancer. Our biological findings can be used to improve clinical management and pave the way for the development of novel therapies for this cancer. (c) 2020 European Association for the Study of the Liver. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
This article was possible thanks to the inputs from the Instituto de Salud Carlos III, ISCIII (PI09/00751, PI10/02082, PI13/02340). The project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 668596 (ChiLTERN) and grant agreement No 826121 (iPC). JCR is supported by the Catalan Agency for Management of University and Research Grants (AGAUR, 2019 FI_B01024). LT is supported by an Accelerator Award (CRUCK, AECC, AIRC) (HUNTER, C9380/A26813). DS is supported by the Gilead Research Scholar in Liver Disease. JML is supported by the European Union's Horizon 2020 research and innovation programme (HEPCAR, 667273-2), Institucio Catalana de Recerca i Estudis Avancats (ICREA), U.S. Department of Defense (CA150272P3), an Accelerator Award (CRUCK, AECC, AIRC) (HUNTER, C9380/A26813), National Cancer Institute, Tisch Cancer Institute (P30-CA196521), Samuel Waxman Cancer Research Foundation, Spanish National Health Institute (SAF2016-76390) and AGAUR (SGR-1358). CA and MRS were supported by Ramon y Cajal (RYC-2010-07249) and Miguel Servet (CPII14/00021) programs of the Ministry of Science and Innovation of Spain and ISCIII, respectively. CA, MRS and MS received funding from CIBERehd (CB06/04/0033) and AGAUR (2017-SGR-490). IGTP is a member of the CERCA network of institutes. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.