Insulin-like growth factors are mitogenic for human keratinocytes and a squamous cell carcinoma

E. Kirk Neely, Vera B. Morhenn, Raymond L. Hintz, Darrell M. Wilson, Ron G. Rosenfeld

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


Normal adult human keratinocytes in monolayer culture and SCL-1, a skin-derived squamous-cell carcinoma cell line, were investigated for the expression of receptors for insulin like growth factors (IGF) and insulin. As demonstrated by affinity crosslinking, radiolabeled IGF-1, IGF-2, and insulin bound specifically to both cell types. Each cell expressed type I IGF receptors, with affinity for IGF-1 > IGF-2 > insulin. Insulin receptors, with highest affinity for insulin, were also present on both cells. However, keratinocytes and SCL-1 cells differed in 125I-IGF-2 binding. 125I-IGF-2-bound to both type I and type II IGF receptors in normal keratinocytes, but bound predominantly to membrane-associated IGF binding proteins in SCL-1. IGF-1 was slightly more potent than IGF-2 in stimulating growth of both keratinocytes and SCL-1 cells. In keratinocytes, concentrations of IGF-1 ranging from 5-100 ng/ml, and of IGF-2 from 50-100 ng/ml, resulted in a significant increase in cell number. At the maximum dose of 100 ng/ml, either IGF-1 or IGF-2 caused a 2.3-times increase in cell number. In SCL-1 cells, IGF-1 was more potent than IGF-2 or insulin at lower concentrations, but either IGF-1 or IGF-2 at the maximal concentration of 333 ng/ml stimulated a 4.7-times increase in thymidine incorporation. The stimulatory effect of insulin in SCL-1 was 10-50 times less potent than that of the IGF. The effect of either IGF on SCL-1 was completely inhibited by the type I IGF receptor antibody alphaIR-3, suggesting that both IGFs are mitogenic through the type I IGF receptor. Insulin action was partially blocked by alphaIR-3, suggesting that insulin can act through both the insulin and type I IGF receptors. It thus appears that IGF-1 and IGF-2 are mitogens for normal and transformed human keratinocytes and that their actions are primarily mediated through the type I IGF receptor, whereas insulin is a mitogen through both the IGF-1 receptor and the insulin receptor.

Original languageEnglish (US)
Pages (from-to)104-110
Number of pages7
JournalJournal of Investigative Dermatology
Issue number1
StatePublished - Jan 1991
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Dermatology
  • Cell Biology


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