title: Keratin 19, a Cancer Stem Cell Marker in Human Hepatocellular Carcinoma.
abstract: OBJECTIVE
  Keratin 19 (K19) is a known marker of poor prognosis and invasion in human hepatocellular carcinoma (HCC). However, the relationship between K19 and cancer stem cells (CSCs) is unclear. Here, we determined whether K19 can be used as a new CSC marker and therapeutic target in HCC.
  
  
  METHODS
  HCC cell lines were transfected with a K19 promoter-driven enhanced green fluorescence protein gene. CSC characteristics, epithelial-mesenchymal transition (EMT), and TGFb/Smad signaling were examined in FACS-isolated K19(+)/K19(-) cells. K19 and TGFb receptor 1 (TGFbR1) expression in 166 consecutive human HCC surgical specimens was examined immunohistochemically.
  
  
  RESULTS
  FACS-isolated single K19(+) cells showed self-renewal and differentiation into K19(-) cells, whereas single K19(-) cells did not produce K19(+) cells. K19(+) cells displayed high proliferation capacity and 5-fluorouracil resistance in vitro. Xenotransplantation into immunodeficient mice revealed that K19(+) cells reproduced, differentiated into K19(-) cells, and generated large tumors at a high frequency in vivo. K19(+) cells were found to be involved in EMT and the activation of TGFb/Smad signaling, and these properties were suppressed by K19 knockdown or treatment with a TGFbR1 inhibitor. The TGFbR1 inhibitor also showed high therapeutic effect against K19(+) tumor in the mouse xenograft model. Immunohistochemistry of HCC specimens showed that compared with K19(-) patients, K19(+) patients had significantly poorer recurrence-free survival and higher tumor TGFbR1 expression.
  
  
  CONCLUSIONS
  K19 is a new CSC marker associated with EMT and TGFb/Smad signaling, and it would thus be a good therapeutic target for TGFbR1 inhibition.
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Kawai
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan. kent@kuhp.kyoto-u.ac.jp.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yasuchika
authors.affiliation: Department of Surgery, Nishikobe Medical Center, Kobe, Japan.
authors.forename: Takamichi
authors.initials: T
authors.lastname: Ishii
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Hokahiro
authors.initials: H
authors.lastname: Katayama
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Elena Yukie
authors.initials: EY
authors.lastname: Yoshitoshi
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ogiso
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Sadahiko
authors.initials: S
authors.lastname: Kita
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Katsutaro
authors.initials: K
authors.lastname: Yasuda
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Fukumitsu
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Mizumoto
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Etsuro
authors.initials: E
authors.lastname: Hatano
authors.affiliation: Department of Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Shinji
authors.initials: S
authors.lastname: Uemoto
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D014408:Biomarkers, Tumor / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D019008:Drug Resistance, Neoplasm; D058750:Epithelial-Mesenchymal Transition; D005472:Fluorouracil / Q000494:pharmacology; D006801:Humans; D053539:Keratin-19 / Q000235:genetics / Q000378:metabolism*; D008113:Liver Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology; D008297:Male; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D015999:Multivariate Analysis; D014411:Neoplastic Stem Cells / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000502:physiology
chemical_list: D000964:Antimetabolites, Antineoplastic; D014408:Biomarkers, Tumor; D053539:Keratin-19; D018125:Receptors, Transforming Growth Factor beta; D051785:Smad Proteins; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625841:TGFBR1 protein, human; C000625842:Tgfbr1 protein, mouse; D005472:Fluorouracil