Induction of alpha-smooth muscle actin by transforming growth factor-beta 1 in quiescent human breast gland fibroblasts. Implications for myofibroblast generation in breast neoplasia

Lab Invest. 1993 Jun;68(6):696-707.


Background: By using a novel experimental system for the study of reactive fibroblast differentiation at the molecular level, we describe the induction of the alpha-isoform of smooth muscle actin by transforming growth factor-beta (TGF-beta 1) in human normal breast gland fibroblasts.

Experimental design: The experimental system allowed fibroblasts to plate and remain quiescent and nonreactive but at the same time stay sensitive to environmental cues for more than 2 weeks after explantation. Most important, the biological activity of growth factors and cytokines could be studied without cells entering the cell cycle, thus serving as a model for stromal reactions with little cell turnover.

Results: By use of double-labeling immunocytochemistry, isoelectric focusing, two-dimensional gel electrophoresis, and fluorography, evidence is presented that the effect of TGF-beta 1 is dose-dependent with a maximal response above 80 pg/ml and a course of 6 days. No other growth factor/cytokine tested (platelet-derived growth factor, interleukin-1, insulin-like growth factor-1, acidic fibroblast growth factor, basic fibroblast growth factor, epidermal growth factor, and interferon-gamma) could induce alpha-smooth muscle actin on their own or potentiate the effect of TGF-beta 1. In an inhibitory assay, only basic fibroblast growth factor was found to prevent the action of TGF-beta 1. The relative contribution of TGF-beta 1-like activity to carcinoma cell induced alpha-smooth muscle actin in fibroblasts was deciphered using TGF-beta neutralizing antibodies and medium conditioned by two different breast carcinoma cell lines. Conditioned medium elicited a fibroblast response indistinguishable from that obtained with exogenously added TGF-beta 1, and indeed neutralization attributed the entire response to the sole effect of secreted TGF-beta 1-like activity.

Conclusions: These results provide a strategy for the molecular characterization of epithelial-stromal interaction in breast neoplasia.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / drug effects
  • Actins / metabolism*
  • Breast / cytology
  • Breast / drug effects
  • Breast / metabolism*
  • Breast Neoplasms / metabolism
  • Carcinoma / metabolism
  • Cell Line
  • Female
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism*
  • Humans
  • Muscle, Smooth
  • Platelet-Derived Growth Factor / pharmacology
  • Transforming Growth Factor beta / pharmacology*
  • Tumor Cells, Cultured


  • Actins
  • Platelet-Derived Growth Factor
  • Transforming Growth Factor beta