title: Head and neck cancer stem cells: the side population.
abstract: OBJECTIVE
  The cancer stem cell (CSC) theory concludes that a subpopulation of cancer cells, the cancer stem cells, can self-renew and are responsible for tumor growth. Previous studies have identified cells able to efflux Hoechst 33342 dye as the side population (SP). SP cells and CSCs share many characteristics, suggesting the SP isolated from malignant tumors contains CSCs.
  
  
  METHODS
  Experimental Study.
  
  
  METHODS
  The SP was isolated from a head and neck cancer cell line and analyzed for CSC-like characteristics.
  
  
  RESULTS
  The SP demonstrated the ability to reproduce both SP and non-side population (NSP) cells from as few as one cell. The SP had lower expression of active β-catenin and more resistance to 5-fluorouracil; the SP also demonstrated greater expression of Bmi-1 (4.3-fold) and ABCG2 (1.4-fold). SP cells were able to produce tumors in an animal model, whereas NSP were not. SPs were identified in two primary human tumors.
  
  
  CONCLUSIONS
  This work adds to the evidence that the SP in head and neck cancer represents cells with CSC properties and provides a method by which CSCs can be isolated and studied.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of South Florida, Tampa, Florida, USA.
authors.forename: Mark H
authors.initials: MH
authors.lastname: Tabor
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Clay
authors.forename: John H
authors.initials: JH
authors.lastname: Owen
authors.forename: Carol R
authors.initials: CR
authors.lastname: Bradford
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Carey
authors.forename: Gregory T
authors.initials: GT
authors.lastname: Wolf
authors.forename: Mark E
authors.initials: ME
authors.lastname: Prince
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology*; D045744:Cell Line, Tumor; D002469:Cell Separation; D004354:Drug Screening Assays, Antitumor; D005472:Fluorouracil / Q000494:pharmacology; D006801:Humans; D007822:Laryngeal Neoplasms / Q000473:pathology; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000473:pathology*; D010039:Otorhinolaryngologic Neoplasms / Q000473:pathology*; D058985:Side-Population Cells / Q000187:drug effects / Q000473:pathology*; D014410:Tumor Stem Cell Assay
chemical_list: D000964:Antimetabolites, Antineoplastic; D005472:Fluorouracil