Increase of free insulin-like growth factor-1 in normal human breast in vivo late in the menstrual cycle

Breast Cancer Res Treat. 2003 Jul;80(2):193-8. doi: 10.1023/A:1024575103524.

Abstract

Prolonged exposure to endogenous and exogenous sex steroids increases the risk of breast cancer but the mechanisms are poorly understood. Increased levels of circulating insulin-like growth factor-1 (IGF-1) and low levels of IGF binding protein are associated with increased risk of breast cancer suggesting that IGF-1 has to be in its free form to be biologically active. Little is known about sex steroid regulation of IGF-1 locally in the breast. In this study microdialysis was used to determine the local levels of free IGF-1 in normal human breast tissue in healthy female volunteers during the menstrual cycle. The results showed that the extracellular levels of free IGF-1 locally in the breast were doubled in the luteal phase, when estradiol and progesterone levels were elevated, compared with the follicular phase. In plasma, free IGF-1 levels also exhibited a cyclic variation but to a less extent. The increased local levels of the free form of IGF-1 may promote proliferation in the breast epithelium. This could be important in sex steroid dependent breast cancer development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Breast / metabolism*
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Insulin-Like Growth Factor I / metabolism*
  • Menstrual Cycle*
  • Microdialysis
  • Reference Values

Substances

  • Insulin-Like Growth Factor I