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Somatostatin analog induces insulin-like growth factor binding protein-1 (IGFBP-1) expression in human hepatoma cells

S G Ren1, S Ezzat, S Melmed

  • 1Division of Endocrinology & Metabolism, Cedars-Sinai Medical Center-UCLA School of Medicine 90048.

Endocrinology
|November 1, 1992
PubMed

Insights

Octreotide, a somatostatin analog, boosts Insulin-like Growth Factor Binding Protein-1 (IGFBP-1) in liver cells. This effect occurs independently of pituitary hormones, suggesting a new way octreotide works.

Area of Science:

  • Endocrinology
  • Molecular Biology
  • Hepatology

Background:

  • Octreotide is known to suppress growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in circulation.
  • Hepatoma (HepG2) cells are utilized for their selective expression of IGFBP-1.
  • The pituitary-independent actions of octreotide require further investigation.

Purpose of the Study:

  • To investigate the effect of octreotide on IGFBP-1 expression in human hepatoma (HepG2) cells.
  • To determine if octreotide's action on IGFBP-1 is independent of insulin and GH.
  • To explore a novel pituitary-independent mechanism of octreotide action.

Main Methods:

  • Treatment of HepG2 cells with varying concentrations of octreotide (6 nM and 60 nM) for different time points (12 and 24 hours).
  • Quantification of IGFBP-1 levels using ligand blotting.
  • Assessment of IGFBP-1 mRNA expression.
  • Evaluation of additive effects with cholera toxin and forskolin.

Main Results:

  • Octreotide significantly stimulated IGFBP-1 levels in HepG2 cells, with a 4.1-fold increase after 24 hours at 60 nM (p < 0.001).
  • Induction of IGFBP-1 was observable as early as 12 hours with 6 nM octreotide (1.5-fold, p < 0.03).
  • Octreotide also induced IGFBP-1 mRNA expression by 2.7-fold and acted additively with cholera toxin and forskolin, independent of insulin and GH.

Conclusions:

  • Octreotide effectively induces both basal and stimulated IGFBP-1 expression in hepatocytes.
  • This induction mechanism is independent of pituitary hormones like GH and also insulin.
  • The upregulation of IGFBP-1 by octreotide represents a novel pituitary-independent pathway that may influence peripheral IGF-1 action.

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