New therapeutic strategies for Hepatocellular carcinoma based on epigenetic targeting

JUAN BAYO; ESTEBAN FIORE; ALEJANDRINA REAL; ESTANISLAO PEIXOTO; MARIANA MALVICINI; MARCELO RODRIGUEZ; SOFÍA GOMEZ-BUSTILLO; MARIANA GARCÍA; GUILLERMO MAZZOLINI

Buenos Aires

Congreso; Reunión Conjunta SAIC, SAI y SAFE; 2016

Hepatocellular carcinoma (HCC) is a health problem worldwide and new therapeutic strategies are urgently needed. The hepatocarcinogenesis process involves several genetic and epigenetic alterations. In particular, deregulation of epigenetic enzymes which catalyze post-translational modification of histones could affect DNA accessibility resulting in changes on gene transcription, DNA repair and cell replication. The aim of this work was to identify epigenetic enzymes related with poor HCC patients prognosis and target them with specific inhibitors. Public clinical and RNA-Seq data of tumors patients with HCC and adjacent tissue from The Cancer Genome Atlas (TCGA) were analysed using the cBioPortal and the FireBrowser portals. Analysis of 97 epigenetic enzymes using the TCGA data showed a significantly poorer survival for patients bearing HCC that expressed high levels of KDM5B (Jumonji demethylase), LSD-1 (histone demethylase) and EZH2 (histone methyltransferase). Interesting, in comparison with non-tumor tissues, KDM5B and EZH2 are overexpressed in HCC. Then, we evaluated 3 specific inhibitors (JIB-04 for KDM5B, GSK-LSD1 for LSD-1 and DZNEP for EZH2) as therapeutic strategy for HCC in vitro. We performed an MTT cell viability assay in a panel of 7 HCC cell lines. The range of IC50 values after 4 days of drug exposure showed an stronger antitumoral effect for JIB-04 (20-250 nM) than for GSK-LSD1 (120-650 nM) or DZNEP (140nM-878µM). Moreover, apoptosis and cell cycle analysis showed that JIB-04 induce a strong cell cycle arrest and an increase in the % of apoptotic cells in HCC cell lines. Finally, qPCR of HCC cells treated with JIB-04 showed the downregulation of proliferative (CCNB1, PCNA, SKP2) and the upregulation of antiproliferative/proapoptotic genes ( DDIT4 and CCNG2). Our results indicate that epigenetic enzymes are interesting targets for therapeutic strategies against HCC. Moreover, specific inhibitors are promising tools to develop new HCC therapies.