Stiff stroma increases breast cancer risk by inducing the oncogene ZNF217
Jason J. Northey, … , Laurie E. Littlepage, Valerie M. Weaver
Jason J. Northey, … , Laurie E. Littlepage, Valerie M. Weaver
Published July 28, 2020
Citation Information: J Clin Invest. 2020;130(11):5721-5737. https://doi.org/10.1172/JCI129249.
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Research Article Oncology

Stiff stroma increases breast cancer risk by inducing the oncogene ZNF217

Abstract

Women with dense breasts have an increased lifetime risk of malignancy that has been attributed to a higher epithelial density. Quantitative proteomics, collagen analysis, and mechanical measurements in normal tissue revealed that stroma in the high-density breast contains more oriented, fibrillar collagen that is stiffer and correlates with higher epithelial cell density. microRNA (miR) profiling of breast tissue identified miR-203 as a matrix stiffness–repressed transcript that is downregulated by collagen density and reduced in the breast epithelium of women with high mammographic density. Culture studies demonstrated that ZNF217 mediates a matrix stiffness– and collagen density–induced increase in Akt activity and mammary epithelial cell proliferation. Manipulation of the epithelium in a mouse model of mammographic density supported a causal relationship between stromal stiffness, reduced miR-203, higher levels of the murine homolog Zfp217, and increased Akt activity and mammary epithelial proliferation. ZNF217 was also increased in the normal breast epithelium of women with high mammographic density, correlated positively with epithelial proliferation and density, and inversely with miR-203. The findings identify ZNF217 as a potential target toward which preexisting therapies, such as the Akt inhibitor triciribine, could be used as a chemopreventive agent to reduce cancer risk in women with high mammographic density.

Authors

Jason J. Northey, Alexander S. Barrett, Irene Acerbi, Mary-Kate Hayward, Stephanie Talamantes, Ivory S. Dean, Janna K. Mouw, Suzanne M. Ponik, Jonathon N. Lakins, Po-Jui Huang, Junmin Wu, Quanming Shi, Susan Samson, Patricia J. Keely, Rita A. Mukhtar, Jan T. Liphardt, John A. Shepherd, E. Shelley Hwang, Yunn-Yi Chen, Kirk C. Hansen, Laurie E. Littlepage, Valerie M. Weaver

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Figure 7

ZNF217 inhibition with triciribine abrogates stiff collagen matrix–induced mammary epithelial cell proliferation and Akt activity in vivo.

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ZNF217 inhibition with triciribine abrogates stiff collagen matrix–induc...
(A) Immunohistochemical (IHC) staining of paraffin sections from the mammary glands of heterozygous Col1a1tm1Jae (COL+/–; n = 3) and WT (n = 3) mice using a phospho–histone H3–specific antibody. Selected mice were treated with the ZNF217/Akt inhibitor triciribine (TRIC; n = 3 each for WT and COL+/– mice). Scale bar: 50 μm. (B) Quantification of positive phospho–histone H3 staining from A expressed as the percentage of highly positive nuclei area per total epithelial area (n = 14–16). (C) qRT-PCR analysis for miR-203 using RNA isolated from the mammary glands of 10-week-old COL+/– mice and age-matched WT counterparts. Results are normalized to U6 RNA levels and plotted relative to WT (n = 4). (D) IHC staining of paraffin sections as in A using a ZNF217-specific antibody. Scale bar: 50 μm. (E) Quantification of positive ZNF217 staining from D expressed as the percentage of high positive staining in MECs (n = 15). (F) IHC staining of paraffin sections as in A using a phosphorylated Akt substrate–specific antibody. Selected mice were treated with triciribine as in A. Scale bar: 50 μm. (G) Quantification of positive phosphorylated Akt substrate staining from F expressed as the percentage of high positive staining in MECs (n = 12–15). Data are represented as mean ± SEM. *P < 0.05; **P < 0.01; ***P < 0.001 by 2-tailed unpaired Student’s t test (C and E) or Kruskal-Wallis test followed by Dunn’s multiple-comparison test (B and G).