title: Vitamin K2 downregulates the expression of fibroblast growth factor receptor 3 in human hepatocellular carcinoma cells.
abstract: OBJECTIVE
  Vitamin K2 exerts an antitumor activity on human hepatocellular carcinoma (HCC), however, its inhibitory mechanism has not yet been clarified. This study was designed to identify the attractive target molecule of vitamin K2 and shed some light on its effects on fibroblast growth factor receptor (FGFR)3 in HCC cells.
  
  
  METHODS
  The changes in the gene expression of HuH-7 after vitamin K2 treatment were evaluated by a DNA chip analysis. The mRNA and protein levels of FGFR were evaluated by semiquantitative reverse transcription polymerase chain reaction (RT-PCR), real-time PCR and western blot analysis. The promoter activity of the FGFR3 gene was measured by a dual-luciferase assay.
  
  
  RESULTS
  The DNA chip analysis revealed different inhibitory rates of gene expression of FGFR3 (60.6%) and FGFR1 (19.4%) after vitamin K2 treatment. Vitamin K2 suppresses the proliferation of HuH-7 in a dose-dependent manner and its inhibitory rate reached approximately 61.8% at the dose of 30 microM. FGFR3 mRNA was significantly reduced based on semiquantitative RT-PCR and decreased 61.5% by a real-time PCR method after vitamin K2 treatment, but FGFR1 mRNA was not. The level of FGFR3 protein was also reduced by vitamin K2 treatment. The luciferase assay demonstrated that vitamin K2 significantly suppressed the promoter activity of FGFR3. Furthermore, the FGFR3-ERK1/2 signaling pathway was suppressed by vitamin K2 treatment.
  
  
  CONCLUSIONS
  These findings suggest that vitamin K2 may suppress the proliferation of HCC cells through the downregulation of the FGFR3 expression. The transcriptional suppression of FGFR3 may be a novel mechanism of the vitamin K2 action for HCC cells.
authors.affiliation: Division of Hepatobiliary and Pancreatic Medicine, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan.
authors.forename: Ke
authors.initials: K
authors.lastname: Cao
authors.forename: Weidong
authors.initials: W
authors.lastname: Liu
authors.forename: Hideji
authors.initials: H
authors.lastname: Nakamura
authors.forename: Hirayuki
authors.initials: H
authors.lastname: Enomoto
authors.forename: Teruhisa
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Masaki
authors.initials: M
authors.lastname: Saito
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Imanishi
authors.forename: Soji
authors.initials: S
authors.lastname: Shimomura
authors.forename: Peiguo
authors.initials: P
authors.lastname: Cao
authors.forename: Shuhei
authors.initials: S
authors.lastname: Nishiguchi