Autocrine growth stimulation of the MCF 7 breast cancer cells by the estrogen-regulated 52 K protein

Endocrinology. 1986 Apr;118(4):1537-45. doi: 10.1210/endo-118-4-1537.


The growth of MCF 7 human breast cancer cells is stimulated in vitro by estradiol (E2) and we have previously shown that estrogen-regulated glycoproteins released into the culture medium can partly mimic this effect. In this paper, we evaluate the mitogenic activity of the 52 K glycoprotein, which is a major E2-stimulated protein released by MCF 7 cells. The 52 K protein was purified 600-fold by affinity chromatography on Concanavalin A and an anti-52 K monoclonal antibody Sepharose columns. The 99% purified 52 K protein fraction stimulated the growth of estrogen-deprived MCF 7 cells. A mean 1.7-fold increase was obtained with nanomolar concentrations of seven different preparations of 52 K protein. This stimulation represented 40% of the mitogenic effect of E2. Both the 52 K protein and E2 induced microvilli at the cell surface but the effect of the 52 K protein occurred earlier. Other putative growth factors which are also stimulated by E2 and observed by [35S]cysteine labeling did not comigrate with the purified 52 K protein. Finally, the labeled 52 K protein was found to enter MCF 7 cells and to be processed into an immunoreactive 34 K protein. These data indicate that the E2-regulated 52 K glycoprotein is an autocrine mitogen on MCF 7 cells in culture and support the hypothesis that estrogens stimulate the growth of mammary cancer via this (and possibly other) secreted protein(s) acting as autocrine (and paracrine?) growth factors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal
  • Breast Neoplasms / ultrastructure*
  • Cell Division / drug effects
  • Cell Line
  • Chromatography, Affinity
  • Dose-Response Relationship, Drug
  • Electrophoresis, Polyacrylamide Gel
  • Estradiol / pharmacology
  • Female
  • Fluorometry
  • Humans
  • Microscopy, Electron, Scanning
  • Molecular Weight
  • Neoplasm Proteins / pharmacology*
  • Surface Properties


  • Antibodies, Monoclonal
  • Neoplasm Proteins
  • estrogen regulated protein
  • Estradiol