Somatostatin analog induces insulin-like growth factor binding protein-1 (IGFBP-1) expression in human hepatoma cells.
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.
Ren
S G
SG
Division of Endocrinology & Metabolism, Cedars-Sinai Medical Center-UCLA School of Medicine 90048.
Ezzat
S
S
Melmed
S
S
Braunstein
G D
GD
D015152:Blotting, Northern; D006528:Carcinoma, Hepatocellular / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D002352:Carrier Proteins / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D002772:Cholera Toxin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1; D008113:Liver Neoplasms / Q000737:chemistry* / Q000235:genetics / Q000473:pathology; D015282:Octreotide / Q000494:pharmacology*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D011863:Radioimmunoassay; D013004:Somatostatin / Q000031:analogs & derivatives*; D014407:Tumor Cells, Cultured / Q000737:chemistry / Q000378:metabolism / Q000473:pathology
D002352:Carrier Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D012333:RNA, Messenger; D005576:Colforsin; D013004:Somatostatin; D002772:Cholera Toxin; D015282:Octreotide