Insulin-like growth factor binding proteins from cultured human fibroblasts. Characterization and hormonal regulation

C. A. Conover, F. Liu, D. Powell, R. G. Rosenfeld, R. L. Hintz

Research output: Contribution to journalArticlepeer-review

121 Scopus citations


Specific, high affinity insulin-like growth factor (IGF) binding proteins are secreted by human fibroblasts in culture. By multiple criteria, the species of IGF binding proteins produced by human fibroblasts are distinct from the HepG2/amniotic fluid IGF binding protein, but share many characteristics with the growth hormone-dependent IGF binding protein forms predominant in normal adult human plasma. Treatment of cultured human fibroblasts with growth hormone produced an increase in IGF binding protein activity in the medium, while addition of glucocorticoids markedly diminished IGF binding activity. Insulin, epidermal growth factor, platelet-derived growth factor, and progesterone had no effect on IGF binding activity in fibroblast media. In comparison, HepG2 IGF binding activity was enhanced by progesterone, decreased by insulin, and unaffected by growth hormone or glucocorticoid treatment. Five molecular forms of IGF binding proteins were identified by Western ligand blots in human fibroblast conditioned medium, with M(r) = 41,500, 37,000, 32,000, 28,000, and 23,000. In human fibroblast conditioned medium, the M(r) = 41,500 and 37,000 IGF binding protein species were abundant, as in normal human plasma, with a major M(r) = 23,000 form which was a minor component in plasma.

Original languageEnglish (US)
Pages (from-to)852-859
Number of pages8
JournalJournal of Clinical Investigation
Issue number3
StatePublished - 1989
Externally publishedYes

ASJC Scopus subject areas

  • General Medicine


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