Evidence for insulin-like growth factor (IGF)-independent transcriptional regulation of IGF binding protein-3 by growth hormone in SKHEP-1 human hepatocarcinoma cells

Zoran S. Gucev, Youngman Oh, Kevin M. Kelley, Jose I. Labarta, Peter Vorwerk, Ronald (Ron) Rosenfeld

Research output: Contribution to journalArticle

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Abstract

Insulin-like growth factor (IGF)-binding protein-3 (IGFBP-3) is a polypeptide that forms a ternary complex with IGFs and an acid-labile subunit. The hormonal regulation of the components of this complex is highly controversial, and both IGF-I and GH have been shown to mediate the expression/synthesis of IGFBP-3. This study investigates the regulation of IGFBP-3 protein, measured by RIA and Western ligand blot, and messenger RNA (mRNA) expression, measured by Northern analysis and reverse transcriptase- PCR, in SKHEP-1 human hepatocarcinoma cells. SKHEP-1 cells significantly increased the IGFBP-3 concentrations in conditioned medium (CM) when treated with GH (0.1-10 ng/ml), IGF-I (1-100 ng/ml), or Des(1-3)-IGF-I (1-100 ng/ml) in a dose-dependent manner (>3-fold). The increase in IGFBP-3 protein concentrations in CM was accompanied by a corresponding increase in IGFBP-3 mRNA levels. Interestingly, time-course studies showed that the GH-induced increase in IGFBP-3 mRNA preceded the IGF-I-induced increase (6 h for GH- induced IG-FBP-3 mRNA; 12 h for IGF-I-induced IGFBP-3 mRNA). The half-life of IGFBP-3 mRNA was evaluated after transcriptional arrest by treatment with a RNA polymerase II inhibitor (5,6-dichloro-1β-D-ribofuranosylbenzimidazole), and was found to be 14-18 h and unaltered by GH or IGF-I treatment. The induction of IGFBP-3 by GH was not due to the indirect action of locally synthesized IGF-I, because 1) no immunoreactive IGF-I was detected in the CM of control or GH-treated cells; 2) Northern blots revealed no IGF-I mRNA expression in SKHEP-1 cells; 3) reverse transcriptase-PCR did not detect any expression of the IGF-I gene; and 4) time-course studies showed an earlier increase in IGFBP-3 mRNA after GH treatment than after IGF-I treatment. Thus, the results obtained in this study are consistent with an IGF-I-independent regulation of IGFBP-3 gene expression by GH.

Original languageEnglish (US)
Pages (from-to)1464-1470
Number of pages7
JournalEndocrinology
Volume138
Issue number4
DOIs
StatePublished - 1997

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Insulin-Like Growth Factor Binding Protein 3
Somatomedins
Insulin-Like Growth Factor I
Growth Hormone
Messenger RNA
Conditioned Culture Medium
Reverse Transcriptase Polymerase Chain Reaction
RNA Polymerase II
Northern Blotting
Half-Life
Proteins
Western Blotting

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Evidence for insulin-like growth factor (IGF)-independent transcriptional regulation of IGF binding protein-3 by growth hormone in SKHEP-1 human hepatocarcinoma cells. / Gucev, Zoran S.; Oh, Youngman; Kelley, Kevin M.; Labarta, Jose I.; Vorwerk, Peter; Rosenfeld, Ronald (Ron).

In: Endocrinology, Vol. 138, No. 4, 1997, p. 1464-1470.

Research output: Contribution to journalArticle

Gucev, Zoran S. ; Oh, Youngman ; Kelley, Kevin M. ; Labarta, Jose I. ; Vorwerk, Peter ; Rosenfeld, Ronald (Ron). / Evidence for insulin-like growth factor (IGF)-independent transcriptional regulation of IGF binding protein-3 by growth hormone in SKHEP-1 human hepatocarcinoma cells. In: Endocrinology. 1997 ; Vol. 138, No. 4. pp. 1464-1470.
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AU - Labarta, Jose I.

AU - Vorwerk, Peter

AU - Rosenfeld, Ronald (Ron)

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