Regulation of heparin-binding EGF-like growth factor expression by phorbol ester in a human hepatoma-derived cell line.
Heparin-binding EGF-like growth factor (HB-EGF) is a recently identified potent mitogen for smooth muscle cells and fibroblasts. HB-EGF has been shown to be an EGF receptor ligand, and also to stimulate epithelial cell growth. A human hepatoma-derived cell line, Mahlavu, was analyzed for the production of HB-EGF mRNA and active HB-EGF protein. It was found that the cell line synthesized very low or undetectable basal level of HB-EGF mRNA. However, the addition of 12-O-tetradecanoylphorbol-13-acetate (TPA) led to a rapid and transient rise in HB-EGF mRNA level. HB-EGF in Mahlavu cells appears to be regulated by a protein kinase C (PKC) pathway, since PKC inhibitors, H7, staurosporin, and calphostin C, abrogated the induction of HB-EGF mRNA by TPA. Unlike vascular smooth muscle cells, induction of HB-EGF gene transcription by TPA was blocked completely by incubation with cycloheximide, suggesting that protein synthesis may be a prerequisite for HB-EGF gene transcription in Mahlavu cells. Mahlavu cells were also found to release a bioactive HB-EGF-like protein into conditioned medium which stimulates DNA synthesis in EP170.7 cells. This activity was neutralized by an anti-HB-EGF antibody. These results indicate that HB-EGF gene transcription is regulated via a PKC pathway, resulting in secretion of active HB-EGF into the culture medium of hepatoma-derived Mahlavu cells.
Ito
N
N
Second Department of Internal Medicine, Osaka University Medical School, Suita, Japan.
Higashiyama
S
S
Kawata
S
S
Tamura
S
S
Kiso
S
S
Tsushima
H
H
Nakagawa
T
T
Matsuzawa
Y
Y
Taniguchi
N
N
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular; D003513:Cycloheximide / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects; D006493:Heparin / Q000378:metabolism*; D066257:Heparin-binding EGF-like Growth Factor; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D009281:Naphthalenes / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis*; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
C587883:HBEGF protein, human; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; D009281:Naphthalenes; D012333:RNA, Messenger; D004815:Epidermal Growth Factor; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D006493:Heparin; D003513:Cycloheximide; D011493:Protein Kinase C; D019311:Staurosporine; C058819:calphostin C; D013755:Tetradecanoylphorbol Acetate