In utero estrogenic endocrine disruption alters the stroma to increase extracellular matrix density and mammary gland stiffness

Breast Cancer Res. 2020 May 5;22(1):41. doi: 10.1186/s13058-020-01275-w.


Background: In utero endocrine disruption is linked to increased risk of breast cancer later in life. Despite numerous studies establishing this linkage, the long-term molecular changes that predispose mammary cells to carcinogenic transformation are unknown. Herein, we investigated how endocrine disrupting compounds (EDCs) drive changes within the stroma that can contribute to breast cancer susceptibility.

Methods: We utilized bisphenol A (BPA) as a model of estrogenic endocrine disruption to analyze the long-term consequences in the stroma. Deregulated genes were identified by RNA-seq transcriptional profiling of adult primary fibroblasts, isolated from female mice exposed to in utero BPA. Collagen staining, collagen imaging techniques, and permeability assays were used to characterize changes to the extracellular matrix. Finally, gland stiffness tests were performed on exposed and control mammary glands.

Results: We identified significant transcriptional deregulation of adult fibroblasts exposed to in utero BPA. Deregulated genes were associated with cancer pathways and specifically extracellular matrix composition. Multiple collagen genes were more highly expressed in the BPA-exposed fibroblasts resulting in increased collagen deposition in the adult mammary gland. This transcriptional reprogramming of BPA-exposed fibroblasts generates a less permeable extracellular matrix and a stiffer mammary gland. These phenotypes were only observed in adult 12-week-old, but not 4-week-old, mice. Additionally, diethylstilbestrol, known to increase breast cancer risk in humans, also increases gland stiffness similar to BPA, while bisphenol S does not.

Conclusions: As breast stiffness, extracellular matrix density, and collagen deposition have been directly linked to breast cancer risk, these data mechanistically connect EDC exposures to molecular alterations associated with increased disease susceptibility. These alterations develop over time and thus contribute to cancer risk in adulthood.

Keywords: Bisphenol A; Bisphenol S; Breast cancer; Collagen; Diethylstilbestrol; Endocrine disruptors; Extracellular matrix; Mammary gland stiffness.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Benzhydryl Compounds / toxicity
  • Endocrine Disruptors / toxicity*
  • Estrogens, Non-Steroidal / pharmacology
  • Extracellular Matrix / drug effects
  • Extracellular Matrix / immunology
  • Extracellular Matrix / pathology*
  • Female
  • Fibroblasts / immunology
  • Fibroblasts / pathology
  • Mammary Glands, Animal / drug effects
  • Mammary Glands, Animal / immunology
  • Mammary Glands, Animal / metabolism
  • Mammary Glands, Animal / pathology*
  • Mice
  • Phenols / toxicity
  • Pregnancy
  • Prenatal Exposure Delayed Effects / chemically induced
  • Prenatal Exposure Delayed Effects / metabolism
  • Prenatal Exposure Delayed Effects / pathology*
  • Stromal Cells / drug effects
  • Stromal Cells / immunology
  • Stromal Cells / pathology*
  • Transcriptome


  • Benzhydryl Compounds
  • Endocrine Disruptors
  • Estrogens, Non-Steroidal
  • Phenols
  • bisphenol A