Analysis of insulin-like growth factor i gene expression in malignancy: Evidence for a paracrine role in human breast cancer Academic Article uri icon


MeSH Major

  • Breast Neoplasms
  • Insulin-Like Growth Factor I
  • Somatomedins


  • Insulin-like growth factor I (IGF-I) activity has been reported to be produced by several human cancers. Identification of RNAs transcribed from the IGF-I gene has been complicated by the detection of multiple hybridizing bands on Northern analysis. To determine if any of these RNAs are transcribed from the IGF-I gene, we have used a sensitive and specific ribonuclease (RNAse) protection assay for IGF-I. We have also studied the breast cancer tissue expression of IGF-I using in situ hybridization histochemistry. We have found no IGF-I mRNA in breast (zero of 11) or colon cancer (zero of 9) cell lines; both of these tumors have been previously reported to express IGF-I mRNA. However, three of three neuroepithelioma and one of two Ewing's sarcoma cell lines express IGF-I mRNA; therefore, in these tumors IGF-I may be an autocrine growth factor. In contrast to breast cancer cell lines, RNA extracted from breast tissues has easily detectable IGF-I mRNA. In situ hybridizations show that IGF-I mRNA is expressed in the stromal cells, and not by normal or malignant epithelial cells. These findings suggest that although IGF-I is not produced by breast epithelial cells it may function as either a paracrine stimulator of epithelial cells or an autocrine stimulator of stromal cells.

publication date

  • January 1989



  • Academic Article



  • eng

Digital Object Identifier (DOI)

  • 10.1210/mend-3-3-509

PubMed ID

  • 2747657

Additional Document Info

start page

  • 509

end page

  • 17


  • 3


  • 3