title: Laminin-332 sustains chemoresistance and quiescence as part of the human hepatic cancer stem cell niche.
abstract: OBJECTIVE
  Cancer stem cells (CSCs) are thought to be persistent in tumours due to their chemoresistance and to cause relapse and metastasis. Hepatic carcinomas displaying hepatic progenitor cell (HPC) features have been associated with a poor prognosis, though it remains unclear how CSCs relate to these different histological subtypes.
  
  
  METHODS
  Candidate CSCs were isolated using the side population (SP) technique from primary tissue samples diagnosed as keratin(K)19-negative or -positive hepatocellular carcinoma (HCC) or as combined hepatocellular/cholangiocarcinoma and analysed for gene and protein expression. The effect of laminin-332 was analysed in vitro by using HCC cell lines and in vivo using a xenograft mouse model.
  
  
  RESULTS
  The size of the SP correlated with the degree of HPC features found in human hepatic cancer, and also showed an elevated mRNA expression of biliary/HPC markers and the extracellular matrix marker LAMC2, the gene encoding the laminin γ2-chain. Immunopositivity for the γ2-chain of laminin-332 was seen in the extracellular matrix surrounding small HPC-like tumour cells with a low proliferation rate. In vitro, laminin-332 increased K19 expression, phosphorylated mTOR and decreased phospho-histone H3 expression, indicating reduced cell mitosis. The effect of laminin-332 was enhanced upon mTORC1 inhibition and diminished when inhibiting mTORC1+C2. Resistance to doxorubicin and sorafenib treatment, and the SP fraction increased in the coated condition. In vivo, laminin-332 reduced tumour growth and sustained K19 expression.
  
  
  CONCLUSIONS
  In this study we identified a prominent role for laminin-332 as part of the specialised CSC niche in maintaining and supporting cell 'stemness', which leads to chemoresistance and quiescence.
authors.affiliation: Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium. Electronic address: olivier.govaere@med.kuleuven.be.
authors.forename: Olivier
authors.initials: O
authors.lastname: Govaere
authors.affiliation: Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.
authors.forename: Jasper
authors.initials: J
authors.lastname: Wouters
authors.affiliation: Department of Medicine I, Institute of Cancer Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Michaela
authors.initials: M
authors.lastname: Petz
authors.affiliation: Department of Hepatology & Gastroenterology, Ghent University, Ghent, Belgium.
authors.forename: Yves-Paul
authors.initials: YP
authors.lastname: Vandewynckel
authors.affiliation: Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Van den Eynde
authors.affiliation: Department of Abdominal Surgery, KU Leuven and University Hospitals Leuven, Leuven, Belgium.
authors.forename: Anke
authors.initials: A
authors.lastname: Van den Broeck
authors.affiliation: Department of Biomedical Sciences, Liver Cell Biology Laboratory, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Stefaan
authors.initials: S
authors.lastname: Verhulst
authors.affiliation: Department of Biomedical Sciences, Liver Cell Biology Laboratory, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Laurent
authors.initials: L
authors.lastname: Dollé
authors.affiliation: Department of Development and Regeneration, KU Leuven, Leuven, Belgium.
authors.forename: Lies
authors.initials: L
authors.lastname: Gremeaux
authors.affiliation: Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.
authors.forename: An
authors.initials: A
authors.lastname: Ceulemans
authors.affiliation: Department of Hepatology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.
authors.forename: Frederik
authors.initials: F
authors.lastname: Nevens
authors.affiliation: Department of Biomedical Sciences, Liver Cell Biology Laboratory, Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Leo A
authors.initials: LA
authors.lastname: van Grunsven
authors.affiliation: Department of Abdominal Surgery, KU Leuven and University Hospitals Leuven, Leuven, Belgium.
authors.forename: Baki
authors.initials: B
authors.lastname: Topal
authors.affiliation: Department of Development and Regeneration, KU Leuven, Leuven, Belgium.
authors.forename: Hugo
authors.initials: H
authors.lastname: Vankelecom
authors.affiliation: Department of Medical Biosciences and Human Oncology, Padiglione Semeiotica Medica, Bari, Italy.
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Giannelli
authors.affiliation: Department of Hepatology & Gastroenterology, Ghent University, Ghent, Belgium.
authors.forename: Hans
authors.initials: H
authors.lastname: Van Vlierberghe
authors.affiliation: Department of Medicine I, Institute of Cancer Research, Medical University of Vienna, Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Mikulits
authors.affiliation: Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.
authors.forename: Mina
authors.initials: M
authors.lastname: Komuta
authors.affiliation: Department of Imaging and Pathology, KU Leuven and University Hospitals Leuven, Leuven, Belgium.
authors.forename: Tania
authors.initials: T
authors.lastname: Roskams
mesh_terms: D000818:Animals; D015815:Cell Adhesion Molecules / Q000494:pharmacology*; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D006801:Humans; D053539:Keratin-19 / Q000032:analysis; D008113:Liver Neoplasms / Q000737:chemistry / Q000188:drug therapy* / Q000473:pathology; D051379:Mice; D014411:Neoplastic Stem Cells / Q000737:chemistry / Q000187:drug effects*; D055153:Stem Cell Niche / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases / Q000502:physiology; D000097794:Kalinin
chemical_list: D015815:Cell Adhesion Molecules; D053539:Keratin-19; D058570:TOR Serine-Threonine Kinases; D000097794:Kalinin
keywords: ATP-binding cassette transporters; Cancer stem cell; Extracellular matrix; Hepatic cancer; Microenvironment; Niche; Phenotype switching