Involvement of hepatoma-derived growth factor in the growth inhibition of hepatocellular carcinoma cells by vitamin K(2).
BACKGROUND
Vitamin K(2) has been reported to suppress the growth of human hepatocellular carcinoma (HCC) in vitro and hepatocarcinogenesis in hepatitis C virus (HCV)-related cirrhosis in vivo. Hepatoma-derived growth factor (HDGF) is a unique nuclear targeting growth factor that is highly expressed in HCC cells and is a possible prognostic factor for patients with HCC. We investigated the regulation of HDGF expression by vitamin K(2).


METHODS
Three HCC-derived cell lines, HepG2, HuH-7, and SK-Hep-1, were used. Cell number was determined with the MTT assay. The expression levels of HDGF mRNA and protein were measured by the real-time reverse transcriptase-polymerase chain reaction (PCR) method and ELISA and Western blot analysis, respectively. The HDGF promoter activity was measured by a dual luciferase-reporter assay.


RESULTS
Vitamin K(2) suppressed the growth of the three HCC cell lines in a dose-dependent manner. Vitamin K(2) significantly suppressed the expression of the HDGF protein and mRNA in three cell lines. By a luciferase assay, vitamin K(2) significantly suppressed the promoter activity of the HDGF protein. Based on some luciferase-reporter plasmids containing truncated promoter regions, the possible responsive site of vitamin K(2) seems to reside in the region -1 to -150 bp of the HDGF gene.


CONCLUSIONS
These findings suggested that regulation of the HDGF gene expression is one of the crucial mechanisms of vitamin K(2)-induced cell growth suppression for HCC.
Yamamoto
Teruhisa
T
Division of Hepatobiliary and Pancreatic Medicine, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo, 663-8501, Japan.
Nakamura
Hideji
H
Liu
Weidong
W
Cao
Ke
K
Yoshikawa
Shohei
S
Enomoto
Hirayuki
H
Iwata
Yoshinori
Y
Koh
Noritoshi
N
Saito
Masaki
M
Imanishi
Hiroyasu
H
Shimomura
Soji
S
Iijima
Hiroko
H
Hada
Toshikazu
T
Nishiguchi
Shuhei
S
D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000188:drug therapy / Q000378:metabolism; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D017930:Genes, Reporter; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008113:Liver Neoplasms / Q000188:drug therapy / Q000378:metabolism; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D024482:Vitamin K 2 / Q000008:administration & dosage / Q000494:pharmacology*
D000970:Antineoplastic Agents; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; C051610:hepatoma-derived growth factor; D024482:Vitamin K 2; D008156:Luciferases