Related Experiment Video
Updated: Jul 13, 2026
Changes in Mammary Gland Morphology and Breast Cancer Risk in Rats
Published on: October 16, 2010
Nf1 deficiency modulates the stromal environment in the pretumorigenic rat mammary gland
Menusha Arumugam1, Elizabeth A Tovar1, Curt J Essenburg1
1Department of Cell Biology, Van Andel Research Institute, Grand Rapids, MI, United States.
Background:
Neurofibromin, coded by the NF1 tumor suppressor gene, is the main negative regulator of the RAS pathway and is frequently mutated in various cancers. Women with Neurofibromatosis Type I (NF1)-a tumor predisposition syndrome caused by a germline NF1 mutation-have an increased risk of developing aggressive breast cancer with poorer prognosis. The mechanism by which NF1 mutations lead to breast cancer tumorigenesis is not well understood. Therefore, the objective of this work was to identify stromal alterations before tumor formation that result in the increased risk and poorer outcome seen among NF1 patients with breast cancer.
Approach:
To accurately model the germline monoallelic NF1 mutations in NF1 patients, we utilized an Nf1-deficient rat model with accelerated mammary development before presenting with highly penetrant breast cancer.
Results:
We identified increased collagen content in Nf1-deficient rat mammary glands before tumor formation that correlated with age of tumor onset. Additionally, gene expression analysis revealed that Nf1-deficient mature adipocytes in the rat mammary gland have increased collagen expression and shifted to a fibroblast and preadipocyte expression profile. This alteration in lineage commitment was also observed with in vitro differentiation, however, flow cytometry analysis did not show a change in mammary adipose-derived mesenchymal stem cell abundance.
Conclusion:
Collectively, this study uncovered the previously undescribed role of Nf1 in mammary collagen deposition and regulating adipocyte differentiation. In addition to unraveling the mechanism of tumor formation, further investigation of adipocytes and collagen modifications in preneoplastic mammary glands will create a foundation for developing early detection strategies of breast cancer among NF1 patients.
Insights
Neurofibromatosis Type I (NF1) patients have increased breast cancer risk due to NF1 gene mutations. This study found that Nf1 deficiency in rats causes collagen buildup and altered adipocytes in mammary glands, potentially driving tumor development.
Area of Science:
- Oncology
- Genetics
- Cell Biology
Background:
- Neurofibromin (NF1) is a tumor suppressor gene regulating the RAS pathway, frequently mutated in cancers.
- Germline NF1 mutations increase breast cancer risk and worsen prognosis in women with Neurofibromatosis Type I.
- Mechanisms linking NF1 mutations to breast cancer initiation and progression remain unclear.
Purpose of the Study:
- To investigate pre-tumorigenic stromal alterations in the mammary gland associated with NF1 mutations.
- To understand how NF1 deficiency contributes to the increased risk and poorer outcomes in NF1-associated breast cancer.
Main Methods:
- Utilized an Nf1-deficient rat model mimicking human germline NF1 mutations.
- Analyzed mammary gland tissue for collagen content and adipocyte characteristics.
- Performed gene expression analysis and in vitro differentiation assays on adipocytes.
Main Results:
- Increased collagen deposition was observed in Nf1-deficient rat mammary glands prior to tumor formation.
- Nf1-deficient adipocytes exhibited elevated collagen expression and a shift towards fibroblast/preadipocyte profiles.
- In vitro studies confirmed altered adipocyte lineage commitment, though stem cell abundance remained unchanged.
Conclusions:
- NF1 plays a critical role in regulating mammary gland collagen deposition and adipocyte differentiation.
- These findings reveal novel mechanisms underlying NF1-associated breast cancer development.
- Further research into preneoplastic adipocyte and collagen changes may inform early detection strategies for NF1 patients.
