De novo HAPLN1 expression hallmarks Wnt-induced stem cell and fibrogenic networks leading to aggressive human hepatocellular carcinomas.

// Sihem Mebarki 1,2 , Romain Desert 1,2 , Laurent Sulpice 1,2,8 , Marie Sicard 1,2 , Mireille Desille 1,2,6 , Frederic Canal 3,4,5 , Helene Dubois-Pot Schneider 1,2 , Damien Bergeat 1,2,8 , Bruno Turlin 1,2,6 , Pascale Bellaud 7 , Elise Lavergne 1,2 , Remy Le Guevel 9 , Anne Corlu 1,2,9 , Christine Perret 3,4,5 , Cedric Coulouarn 1,2 , Bruno Clement 1,2 and Orlando Musso 1,2 1 Inserm, UMR991, Liver Metabolisms and Cancer, Rennes, France 2 Universite de Rennes 1, Rennes, France 3 Inserm, Institut Cochin, Paris, France 4 Cnrs, UMR8104, Paris, France 5 Universite Paris Descartes, Sorbonne Paris Cite, Paris, France 6 CHU de Rennes, Centre de Ressources Biologiques Sante, Rennes, France 7 Universite de Rennes 1, UMS 18 Biosit, Biogenouest, Rennes, France 8 CHU de Rennes, Department of Gastrointestinal and Hepatobiliary Surgery, Rennes, France 9 Universite de Rennes 1, UMS 18 Biosit, Biogenouest, ImPACcellCore Facility, Rennes, France Correspondence to: Orlando Musso, email: // Keywords : Wnt; β-catenin; epithelial-mesenchymal transition; LGR5; CD44; Gerotarget Received : December 01, 2015 Accepted : April 22, 2016 Published : May 13, 2016 Abstract About 20% hepatocellular carcinomas (HCCs) display wild-type β-catenin, enhanced Wnt signaling, hepatocyte dedifferentiation and bad outcome, suggesting a specific impact of Wnt signals on HCC stem/progenitor cells. To study Wnt-specific molecular pathways, cell fates and clinical outcome, we fine-tuned Wnt/β-catenin signaling in liver progenitor cells, using the prototypical Wnt ligand Wnt3a. Cell biology assays and transcriptomic profiling were performed in HepaRG hepatic progenitors exposed to Wnt3a after β-catenin knockdown or Wnt inhibition with FZD8_CRD. Gene expression network, molecular pathology and survival analyses were performed on HCCs and matching non-tumor livers from 70 patients by real-time PCR and tissue micro-array-based immunohistochemistry. Wnt3a reprogrammed liver progenitors to replicating fibrogenic myofibroblast-like cells displaying stem and invasive features. Invasion was inhibited by 30 nM FZD7 and FZD8 CRDs. Translation of these data to human HCCs revealed two tight gene networks associating cell surface Wnt signaling, stem/progenitor markers and mesenchymal commitment. Both networks were linked by Hyaluronan And Proteoglycan Link Protein 1 (HAPLN1), that appeared de novo in aggressive HCCs expressing cytoplasmic β-catenin and stem cell markers. HAPLN1 was independently associated with bad overall and disease-free outcome. In vitro, HAPLN1 was expressed de novo in EPCAM¯/NCAM+ mesoderm-committed progenitors, upon spontaneous epithelial-mesenchymal transition and de-differentiation of hepatocyte-like cells to liver progenitors. In these cells, HAPLN1 knockdown downregulated key markers of mesenchymal cells, such as Snail, LGR5, collagen IV and α-SMA. In conclusion, HAPLN1 reflects a signaling network leading to stemness, mesenchymal commitment and HCC progression.