Epigenetics and epigenomics of virus-related hepatocellular carcinomas – EpiVirHep

In order to achieve its objective the EpiVirHep project: 1) brought together multidisciplinary expertises from the very basic to clinical research; 2) combined cutting edge innovative technonolgies in molecular biology, molecular virology and high thoughput Next Generation Sequencing (NGS) techniques; 3) linked high technology to clinical application by validating the new findings in relevant clinical settings; 4) included in the validation process low cost methods amenable for analyzing low quantity and/or easy to obtain samples, as they currently obtained in the clinical practice.

EpiVirHep research led to : a) better define the direct contribution of virus and the viral protein HBx in HBV-related HCCs; b) identify a subset of genes activated by the epigenetic regulator PRC2/EZH2 complex in HCC that may serve as prognostic signature; c) shed a new light on how a new class of epidrugs targeting EZH2 activity might be used in HCC treatment; d) launch several new national and international collaborative research projects.

Launch several new national and international collaborative research projects.

The results generated in the frame of the EpiVirHep project have contributed substantial new knowledge on the epigenetic changes that precede and accompany HCC development and progression leading to several high impact original publications (9) and reviews (7) in peer reviewed journals; communications at international (31) and national (7) meetings.

Infection with hepatitis B virus (HBV) continues to be, despite the availability since the early 90’s of the HBV vaccine, a major health problem with about 400 million people chronically infected worldwide. HBV replication drives both disease severity and progression to cirrhosis and HCC development. Long-term nucleos(t)ide analogues administration suppresses viral replication and prevents disease progression and liver-related events, except for HCC development. The development of new therapeutic approaches for the treatment of HBV chronically infected patients and the prevention of HCC development has become a major research goal, as witnessed by the ANRS “HBV cure” initiative.

Hepatocellular carcinoma (HCC) is highly prevalent in many countries and, because of its very poor prognosis, is the third cause of cancer death worldwide. HCC development is driven by multiple viruses (HBV, HCV) and chronic metabolic alterations leading to chronic inflammation, DNA damage, epigenetic and genetic changes that affect both “common” and “etiology specific” oncogenic pathways. Importantly, whereas mutations and chromosomal aberrations have been consistently found in tumor tissues, deregulation of signaling pathways and epigenetic changes are also detected early in the natural history of HCC development, at the stage of cirrhosis or dysplastic nodules.

The general aim of the EpiVirHep project is to investigate, using a combination of molecular biology, cell biology and genome wide Next Generation Sequencing (NGS) techniques, the epigenetic changes that precede and accompany HCC development and progression mainly, but not exclusively, in the setting of HBV chronic liver diseases.

The experimental plan is organized into 3 Tasks, each subdivided into specific Sub-Tasks, aimed to:
a) define the contribution of viral protein HBx and HBc in HBV pathogenicity, liver tumors development and progression;
b) identify the gene network controlled by the PRC2 complex in normal and neoplastic liver cells and to investigate the functional consequences of genetic knockdown and pharmacological manipulation of Ezh2;
c) identify genes and ncRNAs co-regulated by IL6/STAT3 and the PRC2 complex in HBV, HCV and NASH-related cancers and investigate their possible modulation by metformin.

Pathologic activation of Ezh2 and PRC2, either through Ezh2 overexpression or Ezh2 activating mutations, is among the most common alterations observed in a wide variety of cancerous tissue types, including non-hodgkin’s lymphoma, prostate, breast and HCCs
The relevance of PRC2 complex and Ezh2 deregulation in HCCs, and in particular in HBV-related HCCs, is supported by the frequent up-regulation of Ezh2 in HCCs and the ability of EzH2 knockdown in HCC cells to reverse tumorigenicity in a nude mouse model and to up-regulate several miRNAs that negatively regulate HCC progression and invasion.

The EpiVirHep project has the ambition to utilize cutting edge innovative technologies and to link high technology to clinical application by extensive validation of the new findings in patients samples from relevant clinical settings. EpiVirHep success and its translational value will very much depend on the access to liver samples from well defined categories of patients. This will be achieved through the collaboration with leading clinical groups in HBV and HCC research in Italy [Prof A Craxi, University of Palermo) and Prof M Colombo (University of Milan)] and in France [Prof F Zoulim (CRCL, Lyon)].

Altogether, the EpiVirHep will not only generate new knowledge and provide new insights on the molecular pathogenesis of virus-related HCCs but will also, hopefully, provide data for the rationale use of anti-Ezh2/PRC2 in HCC treatment and lead to the development of biomarkers for early diagnosis, prognostication and treatment allocation of liver cancer patients.