title: Rapid adherence to collagen IV enriches for tumour initiating cells in oral cancer.
abstract: BACKGROUND
  Although several approaches for identification and isolation of carcinoma cells with tumour initiating properties have been established, enrichment of a population of pure and viable tumour-initiating cells (TICs) is still problematic. This study investigated possibilities to isolate a population of cancer cells with tumour initiating properties based on their adherence properties, rather than expression of defined markers or clonogenicity.
  
  
  METHODS
  Several human cell lines derived from oral dysplasia and oral squamous cell carcinoma (OSCC), as well as primary cells derived from patients with OSCC were allowed to adhere to collagen IV-coated dishes sequentially. Rapid adherent cells (RAC), middle adherent cells (MAC) and late adherent cells (LAC) were then harvested and further investigated for their morphology, stem cell-like properties and molecular profile while grown in vitro and tongue xenotransplantation in NOD-SCID mice at serial dilutions.
  
  
  RESULTS
  RAC showed significantly higher colony forming efficiency (p<0.05), sphere forming ability, greater migration ability (p<0.05), exhibited longer G2 phase and displayed higher expression of integrin β1 and other stem-cell related molecules as compared to MAC and LAC. RAC induced tongue tumours in NOD-SCID mice with the highest incidence. These tumours were also bigger and metastasised more frequently in loco-regional lymph nodes than MAC and LAC.
  
  
  CONCLUSIONS
  These findings prove for the first time that OSCC cells with tumour initiating properties can be enriched based on their rapid adhesiveness to collagen IV. This separation procedure provides a potentially useful tool for isolating TICs in OSCC for further studies on understanding their characteristics and drug-resistant behaviour.
authors.affiliation: The Gade Laboratory of Pathology, Department of Clinical Medicine, University of Bergen, Norway.
authors.forename: Xiao
authors.initials: X
authors.lastname: Liang
authors.affiliation: The Gade Laboratory of Pathology, Department of Clinical Medicine, University of Bergen, Norway.
authors.forename: Tarig Al-Hadi
authors.initials: TA
authors.lastname: Osman
authors.affiliation: The Gade Laboratory of Pathology, Department of Clinical Medicine, University of Bergen, Norway.
authors.forename: Dipak
authors.initials: D
authors.lastname: Sapkota
authors.affiliation: Department of Oral Surgery, Institute of Clinical Dentistry, University of Bergen, Norway; Department of Ear-Nose-and-Throat, Haukeland University Hospital, Bergen, Norway.
authors.forename: Evelyn
authors.initials: E
authors.lastname: Neppelberg
authors.affiliation: Department of Ear-Nose-and-Throat, Haukeland University Hospital, Bergen, Norway.
authors.forename: Stein
authors.initials: S
authors.lastname: Lybak
authors.affiliation: Department of Ear-Nose-and-Throat, Haukeland University Hospital, Bergen, Norway.
authors.forename: Per Gunnar
authors.initials: PG
authors.lastname: Liavaag
authors.affiliation: The Gade Laboratory of Pathology, Department of Clinical Medicine, University of Bergen, Norway; Department of Pathology, Haukeland University Hospital, Bergen, Norway.
authors.forename: Anne Christine
authors.initials: AC
authors.lastname: Johannessen
authors.affiliation: Department of Biomedicine, University of Bergen, Norway.
authors.forename: Hege Karine
authors.initials: HK
authors.lastname: Jacobsen
authors.affiliation: Department of Biomedicine, University of Bergen, Norway; Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.
authors.forename: Per Øyvind
authors.initials: PØ
authors.lastname: Enger
authors.affiliation: The Gade Laboratory of Pathology, Department of Clinical Medicine, University of Bergen, Norway; Department of Pathology, Haukeland University Hospital, Bergen, Norway; Department of Biomedicine, University of Bergen, Norway.
authors.forename: Daniela Elena
authors.initials: DE
authors.lastname: Costea
authors.affiliation: Department of Biomedicine, University of Bergen, Norway. Electronic address: jian.wang@biomed.uib.no.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
mesh_terms: D000818:Animals; D014408:Biomarkers, Tumor / Q000378:metabolism; D063646:Carcinogenesis / Q000473:pathology; D002294:Carcinoma, Squamous Cell / Q000473:pathology / Q000503:physiopathology*; D002448:Cell Adhesion / Q000502:physiology; D002461:Cell Line, Transformed; D024141:Collagen Type IV / Q000494:pharmacology*; D006801:Humans; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009062:Mouth Neoplasms / Q000473:pathology / Q000503:physiopathology*; D009368:Neoplasm Transplantation / Q000379:methods; D014411:Neoplastic Stem Cells / Q000473:pathology / Q000502:physiology*; D014183:Transplantation, Heterologous / Q000379:methods; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; D024141:Collagen Type IV
keywords: Collagen IV; Oral cancer; Rapid adherent cells; Stem cells