Decreased expression of the CCAAT/enhancer binding protein alpha gene involved in hepatocyte proliferation in human hepatocellular carcinomas.
CCAAT/enhancer binding protein alpha (C/EBPalpha), expressed at a high level in liver, plays an important role in proliferation and differentiation of hepatocytes. Previous studies showed that an expression level of the C/EBPalpha gene in hepatocytes was downregulated in response to proliferation signals and that forced expression of the C/EBPalpha gene in a number of cells caused cell cycle arrest. We compared the expression level of the C/EBPalpha gene in surgical specimens between hepatocellular carcinoma and non-tumorous regions of the same patients. In 9 out of 13 cases, the expression level in the tumors was decreased compared with that in corresponding non-tumorous regions. Transfection of the C/EBPalpha gene into C/EBPalpha-negative human hepatocellular carcinoma HLF cells, however, did not influence the rate of cell proliferation or cell cycle. Our present data suggest that the expression of the C/EBPalpha gene was downregulated in the majority of human hepatocellular carcinoma but the expression may not be directly associated with impaired proliferative activity of hepatocellular carcinoma cells.
Tomizawa
Minoru
M
Department of Medicine and Clinical Oncology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba City 260-8670, Japan.
Wang
Yan-Qing
YQ
Ebara
Masaaki
M
Saisho
Hiromitsu
H
Watanabe
Kazuo
K
Nakagawara
Akira
A
Tagawa
Masatoshi
M
D000818:Animals; D015152:Blotting, Northern; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000096:biosynthesis*; D019556:COS Cells; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D002455:Cell Division; D018076:DNA, Complementary / Q000378:metabolism; D015536:Down-Regulation; D005434:Flow Cytometry; D022781:Hepatocytes / Q000473:pathology; D006801:Humans; D008099:Liver / Q000378:metabolism; D008113:Liver Neoplasms / Q000378:metabolism*; D011485:Protein Binding; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
D022763:CCAAT-Enhancer-Binding Protein-alpha; D018076:DNA, Complementary