title: CD49f-positive cell population efficiently enriches colon cancer-initiating cells.
abstract: Cancer stem cells (CSCs) also known as cancer-initiating cells (CICs) show high tumorigenic activity and high chemo- and radiation resistance. It is, therefore, important to identify CSCs reliably to develop novel curative cancer treatments. In this study, we re-evaluated CSC markers of colorectal cancer for their cellular differentiation and tumorigenic activity, with the aim to identify reliable CSC markers. The rates of change in CD44, CD133, CD166, CD24, CD49f and CXCR4 expression during sodium butyrate (NaBT)-induced cell differentiation were assessed in HT29 and Caco2 colon cancer cell lines. Expression levels of target markers were assessed in clinical CRC samples. Tumorigenic activity was assessed on isolated cell fractions identified by multicolor flow cytometric analysis. In the cell differentiation assay, the average percent change was higher in CD44 (-98.2%) and CD49f (-74.4%) compared to CD133 (-17.9%) and CD166 (-49.4%). Expression of CD24 and CXCR4 appeared random in HT29 and Caco2. Expression of CD44, CD49f, CD133 and CD166 was confirmed in all four clinical CRC samples. Limiting dilution assay of CD44- and CD133-expressing cells revealed that only the CD133⁺CD44⁺ population possessed tumorigenic activity. Tumorigenesis was not affected by CD166 expression. Highly tumorigenic cells could be enriched in samples with higher CD49f expression; CD49f⁺ cells showed high tumorigenesis, whereas CD133⁺ and CD44⁺ cells that were negative for CD49f exhibited no tumorigenic activity. Multicolor analysis revealed that CD49f⁺ cells localized in CD44⁺ and CD133⁺ cell fractions. These findings demonstrated that CD49f is an important marker for identifying colorectal CSCs and suggest that the CD49f⁺ cell fraction may be the best candidate for colorectal CSCs.
authors.affiliation: Department of Gastroenterological Surgery, Graduate School of Medicine, Osaka University, Suita, Osaka 565-0871, Japan.
authors.forename: Naotsugu
authors.initials: N
authors.lastname: Haraguchi
authors.forename: Hideshi
authors.initials: H
authors.lastname: Ishii
authors.forename: Koshi
authors.initials: K
authors.lastname: Mimori
authors.forename: Katsuya
authors.initials: K
authors.lastname: Ohta
authors.forename: Mamoru
authors.initials: M
authors.lastname: Uemura
authors.forename: Junichi
authors.initials: J
authors.lastname: Nishimura
authors.forename: Taishi
authors.initials: T
authors.lastname: Hata
authors.forename: Ichiro
authors.initials: I
authors.lastname: Takemasa
authors.forename: Tsunekazu
authors.initials: T
authors.lastname: Mizushima
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Doki
authors.forename: Masaki
authors.initials: M
authors.lastname: Mori
mesh_terms: D000071916:AC133 Antigen; D020410:Activated-Leukocyte Cell Adhesion Molecule / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism*; D020148:Butyric Acid / Q000494:pharmacology; D051927:CD24 Antigen / Q000378:metabolism; D018938:Caco-2 Cells; D063646:Carcinogenesis; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D006023:Glycoproteins / Q000378:metabolism; D019073:HT29 Cells; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis; D039503:Integrin alpha6 / Q000378:metabolism*; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000378:metabolism* / Q000473:pathology; D010455:Peptides / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000378:metabolism
chemical_list: D000071916:AC133 Antigen; D020410:Activated-Leukocyte Cell Adhesion Molecule; D015703:Antigens, CD; D014408:Biomarkers, Tumor; D051927:CD24 Antigen; C514936:CXCR4 protein, mouse; D006023:Glycoproteins; D018960:Hyaluronan Receptors; D039503:Integrin alpha6; C000606023:PROM1 protein, human; D010455:Peptides; C000606024:Prom1 protein, mouse; D019718:Receptors, CXCR4; D020148:Butyric Acid