Stiff stroma increases breast cancer risk by inducing the oncogene ZNF217
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
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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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 2

Tissues with high breast density exhibit elevated levels of linear and dense fibrillar collagens.

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Tissues with high breast density exhibit elevated levels of linear and d...
(A) Trichrome staining of human breast tissue sections to visualize overall collagen matrix abundance (blue) (low MD, n = 4; high MD, n = 9). Scale bars: 100 μm and 50 μm (inset). (B) Quantification of trichrome staining represented as percentage positive (blue) area per field of view. (C–E) Quantification of levels for the indicated fibrillar collagens from the proteomic analysis (MD1–MD4; see Figure 1B). (F) Picrosirius red staining of human breast tissue sections and imaging with polarized light to visualize dense collagen fibers (low MD, n = 6; high MD, n = 9). Scale bars: 100 μm and 100 μm (inset). (G) Quantification of dense collagen (mean intensity of red fibers) visualized by polarized light. (H) Representative images obtained using second harmonic generation (SHG) imaging to visualize the collagen of human breast tissues. Red identifies thicker collagen fibers (bottom). Scale bar: 100 μm. (I) Quantification of collagen fiber orientation using a model approximation (major/minor axis ratio of a fast Fourier transform–fitting [FFT-fitting] ellipse) (low MD, n = 8; high MD, n = 8). (J) SIM-POL imaging of breast tissues with MD1 and MD4 to measure tissue birefringence. Blue→red color indicates increasing birefringence. Scale bar: 20 μm. (K) Quantification of SIM-POL imaging showing mean birefringence (low MD, n = 3, high MD, n = 3). Data are represented as mean ± SEM. #P < 0.1; *P < 0.05; **P < 0.01; ***P < 0.001 by 2-tailed unpaired Student’s t test (G and I), 2-tailed Mann-Whitney U test (B and K), or 1-way ANOVA with Tukey’s multiple-comparison test (C–E).