Abstract
The effects of heparin-binding epidermal growth factor-like growth factor (HB-EGF) on albumin gene expression were analyzed in alpha-fetoprotein (AFP)-producing and AFP-nonproducing human hepatoma cells, HuH-7 and huH-1/cl.2, in which the AFP silencer is inactive and active, respectively. HB-EGF selectively suppressed the AFP enhancer activity, resulting in decreased levels of both albumin and AFP mRNA in HuH-7 cells. In contrast, HB-EGF did not influence the albumin transcripts in huH-1/cl.2 cells or primary culture of rat hepatocytes, although the AFP enhancer activity was reduced by HB-EGF in huH-1/cl.2 cells as well as in HuH-7 cells. These results indicate that the AFP silencer interacts with the AFP enhancer to block its activity regulating both the albumin and AFP promoters, and that HB-EGF downregulates the albumin gene expression only in the absence of the AFP silencer through the repression of the AFP enhancer activity.
MeSH terms
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Animals
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Carcinoma, Hepatocellular / genetics
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Carcinoma, Hepatocellular / metabolism
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Carcinoma, Hepatocellular / pathology*
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Cell Division / drug effects
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Enhancer Elements, Genetic
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Epidermal Growth Factor / pharmacology*
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Gene Expression Regulation, Neoplastic / drug effects*
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Heparin-binding EGF-like Growth Factor
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Humans
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Intercellular Signaling Peptides and Proteins
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Liver / drug effects
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Liver / metabolism
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Liver Neoplasms / genetics
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Liver Neoplasms / metabolism
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Liver Neoplasms / pathology*
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Male
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Neoplasm Proteins / biosynthesis
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Neoplasm Proteins / genetics*
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Promoter Regions, Genetic
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Rats
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Rats, Wistar
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Recombinant Fusion Proteins / pharmacology
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Serum Albumin / biosynthesis
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Serum Albumin / genetics*
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Transfection
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Tumor Cells, Cultured
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alpha-Fetoproteins / biosynthesis*
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alpha-Fetoproteins / genetics
Substances
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HBEGF protein, human
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Hbegf protein, rat
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Heparin-binding EGF-like Growth Factor
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Intercellular Signaling Peptides and Proteins
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Neoplasm Proteins
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Recombinant Fusion Proteins
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Serum Albumin
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alpha-Fetoproteins
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Epidermal Growth Factor