Abstract
As the somatostatin analog octreotide suppresses pituitary GH secretion and circulating IGF-1 levels, we examined its effects on human hepatoma (hep G2) cells which selectively express IGFBP-1. Octreotide (60 nM) stimulated IGFBP-1 up to 4.1-fold (p < 0.001 after 24 hrs). Induction of IGFBP-1 was first detectable after 12 hrs of 6 nM octreotide (1.5-fold, p < 0.03), and was confirmed by ligand blotting. Cholera toxin and forskolin induced IGFBP-1 independently and were also additive with octreotide. IGFBP-1 mRNA expression was induced 2.7-fold by octreotide. Thus, octreotide induces basal and stimulated IGFBP-1 in hepatocytes independently of insulin and GH. As IGFBP-1 may regulate peripheral IGF-1 action, induction of IGFBP-1 represents a novel pituitary-independent mechanism for octreotide action.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Blotting, Northern
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Carcinoma, Hepatocellular / chemistry*
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Carcinoma, Hepatocellular / genetics
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Carcinoma, Hepatocellular / pathology
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Carrier Proteins / analysis*
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Cholera Toxin / pharmacology
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Colforsin / pharmacology
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Electrophoresis, Polyacrylamide Gel
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Gene Expression Regulation, Neoplastic / drug effects
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Humans
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Insulin-Like Growth Factor Binding Protein 1
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Liver Neoplasms / chemistry*
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Liver Neoplasms / genetics
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Liver Neoplasms / pathology
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Octreotide / pharmacology*
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RNA, Messenger / analysis
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RNA, Messenger / genetics
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Radioimmunoassay
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Somatostatin / analogs & derivatives*
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Tumor Cells, Cultured / chemistry
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Tumor Cells, Cultured / metabolism
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Tumor Cells, Cultured / pathology
Substances
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Carrier Proteins
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Insulin-Like Growth Factor Binding Protein 1
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RNA, Messenger
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Colforsin
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Somatostatin
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Cholera Toxin
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Octreotide