New tumor suppressor microRNAs target glypican-3 in human liver cancer

// Flora Cartier 1, 2 , Emilie Indersie 1, 2 , Sarah Lesjean 1, 2 , Justine Charpentier 1, 2 , Katarzyna B. Hooks 1, 2 , Amani Ghousein 1, 2 , Angélique Desplat 1, 2 , Nathalie Dugot-Senant 3 , Véronique Trézéguet 4, 5 , Francis Sagliocco 1, 2 , Martin Hagedorn 1, 2 and Christophe F. Grosset 1, 2 1 University of Bordeaux, Inserm, Groupe de Recherche pour l’Etude du Foie, GREF, U1053, F-33076 Bordeaux, France 2 University of Bordeaux, Inserm, Biothérapies des Maladies Génétiques Inflammatoires et Cancers, BMGIC, U1035, F-33076 Bordeaux, France 3 INSERM US005 - TBM Core, Service for Experimental Histopathology, F-33000 Bordeaux, France 4 University of Bordeaux, F-33000 Bordeaux, France 5 CNRS, UMR5248, Chimie & Biologie des Membranes & des Nano-objets, CBMN, Allée Geoffroy Saint-Hilaire, Bât B14, F-33600 Pessac, France Correspondence to: Christophe F. Grosset, email: christophe.grosset@inserm.fr Keywords: liver, cancer, hepatocellular carcinoma, microRNA, glypican-3 Received: October 13, 2016 Accepted: March 25, 2017 Published: April 17, 2017 ABSTRACT Glypican-3 (GPC3) is an oncogene, frequently upregulated in liver malignancies such as hepatocellular carcinoma (HCC) and hepatoblastoma and constitutes a potential molecular target for therapy in liver cancer. Using a functional screening system, we identified 10 new microRNAs controlling GPC3 expression in malignant liver cells, five of them e.g. miR-4510, miR-203a-3p, miR-548aa, miR-376b-3p and miR-548v reduce GPC3 expression. These 5 microRNAs were significantly downregulated in tumoral compared to non-tumoral liver and inhibited tumor cell proliferation. Interestingly, miR-4510 inversely correlated with GPC3 mRNA and protein in HCC samples. This microRNA also induced apoptosis of hepatoma cells and blocked tumor growth in vivo in the chick chorioallantoic membrane model. We further show that the tumor suppressive effect of miR-4510 is mediated through direct targeting of GPC3 mRNA and inactivation of Wnt/β-catenin transcriptional activity and signaling pathway. Moreover, miR-4510 up-regulated the expression of several tumor suppressor genes while reducing the expression of other pro-oncogenes. In summary, we uncovered several new microRNAs targeting the oncogenic functions of GPC3. We provided strong molecular, cellular and in vivo evidences for the tumor suppressive activities of miR-4510 bringing to the fore the potential value of this microRNA in HCC therapy.