title: Maintenance of HCT116 colon cancer cell line conforms to a stochastic model but not a cancer stem cell model.
abstract: The cancer stem cell (CSC) model, in which a small population of cells within a tumor possesses the ability to self-renew and reconstitute the phenotype of primary tumor, has gained wide acceptance based on evidence over the past decade. It has also been reported that cancer cell lines contain a CSC subpopulation. However, phenotypic differences between CSCs and non-CSCs in cancer cell lines are not better defined than in primary tumors. Furthermore, some cell lines do not have a CSC population, revealed as a side population and expression of CD133. Thus, the identification of CSCs in cancer cell lines remains elusive. Here, we investigated the CSC hierarchy within HCT116 colon cancer cells, which do not have a CD133-positive subpopulation. We examined the expression of alternative CSC markers epithelial specific antigen (ESA) and CD44 in floating-sphere-derived cells, which are known to be the cells of enriching CSCs. Sphere-derived HCT116 cells exhibited heterogeneous expression of ESA and CD44. The two major subpopulations of HCT116 sphere cells (ESA(low)CD44(-/low) and ESA(high)CD44(high)) exhibited a biological/proliferative hierarchy of sphere-forming and soft agar colony-forming activity. However, there was no difference between the two subpopulations in the incidence of xenograft tumors. When ESA(low)CD44(-/low) cells were allowed to aggregate and re-form floating-spheres, the biological/proliferative hierarchy of parental HCT116 spheres was reconstituted, in terms of ESA and CD44 expression. Thus, HCT116 cells have plasticity when they are set in floating-spheres, suggesting that maintenance of the HCT116 cell line conforms to a stochastic model, not a CSC model.
authors.affiliation: Division of Gene Regulation, Institute for Advanced Medical Research, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Kazuharu
authors.initials: K
authors.lastname: Kai
authors.forename: Osamu
authors.initials: O
authors.lastname: Nagano
authors.forename: Eiji
authors.initials: E
authors.lastname: Sugihara
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Arima
authors.forename: Oltea
authors.initials: O
authors.lastname: Sampetrean
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Ishimoto
authors.forename: Masaya
authors.initials: M
authors.lastname: Nakanishi
authors.forename: Naoto T
authors.initials: NT
authors.lastname: Ueno
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Iwase
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Saya
mesh_terms: D000071916:AC133 Antigen; D000818:Animals; D015703:Antigens, CD / Q000032:analysis; D049109:Cell Proliferation; D006023:Glycoproteins / Q000032:analysis; D045325:HCT116 Cells / Q000473:pathology*; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D014411:Neoplastic Stem Cells / Q000473:pathology*; D010455:Peptides / Q000032:analysis; D010641:Phenotype; D018874:Spheroids, Cellular
chemical_list: D000071916:AC133 Antigen; D015703:Antigens, CD; D006023:Glycoproteins; C000606023:PROM1 protein, human; D010455:Peptides; C000606024:Prom1 protein, mouse