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Updated: Apr 12, 2026
Studying TGF-β Signaling and TGF-β-induced Epithelial-to-mesenchymal Transition in Breast Cancer and Normal Cells
Published on: October 27, 2020
Differential Proteome Analysis Identifies TGF-β-Related Pro-Metastatic Proteins in a 4T1 Murine Breast Cancer Model
Misako Sato1, Tsutomu Matsubara2, Jun Adachi3
1Laboratory of Proteome Research, Proteome Research Center, National Institute of Biomedical Innovation, Saito, Osaka, Japan; Department of Hepatology, Graduate School of Medicine, Osaka City University, Osaka, Japan.
Abstract:
Transforming growth factor-β (TGF-β) has a dual role in tumorigenesis, acting as either a tumor suppressor or as a pro-oncogenic factor in a context-dependent manner. Although TGF-β antagonists have been proposed as anti-metastatic therapies for patients with advanced stage cancer, how TGF-β mediates metastasis-promoting effects is poorly understood. Establishment of TGF-β-related protein expression signatures at the metastatic site could provide new mechanistic information and potentially allow identification of novel biomarkers for clinical intervention to discriminate TGF-β oncogenic effects from tumor suppressive effects. In the present study, we found that systemic administration of the TGF-β receptor kinase inhibitor, SB-431542, significantly inhibited lung metastasis from transplanted 4T1 mammary tumors in Balb/c mice. The differentially expressed proteins in the comparison of lung metastases from SB-431542 treated and control vehicle-treated groups were analyzed by a quantitative LTQ Orbitrap Velos system coupled with stable isotope dimethyl labeling. A total of 36,239 peptides from 6,694 proteins were identified, out of which 4,531 proteins were characterized as differentially expressed. A subset of upregulated proteins in the control group was validated by western blotting and immunohistochemistry. The eukaryotic initiation factor (eIF) family members constituted the most enriched protein pathway in vehicle-treated compared with SB-43512-treated lung metastases, suggesting that increased protein expression of specific eIF family members, especially eIF4A1 and eEF2, is related to the metastatic phenotype of advanced breast cancer and can be down-regulated by TGF-β pathway inhibitors. Thus our proteomic approach identified eIF pathway proteins as novel potential mediators of TGF-β tumor-promoting activity.
Insights
Transforming growth factor-β (TGF-β) can promote cancer metastasis. Inhibiting TGF-β signaling with SB-431542 reduced lung metastasis in mice and identified eukaryotic initiation factor (eIF) proteins as key mediators.
Area of Science:
- Oncology
- Molecular Biology
- Proteomics
Background:
- Transforming growth factor-β (TGF-β) exhibits context-dependent roles in cancer, acting as both a tumor suppressor and a promoter of oncogenesis.
- The precise mechanisms by which TGF-β promotes metastasis remain incompletely understood, hindering the development of targeted therapies.
- Identifying TGF-β-regulated protein signatures at metastatic sites is crucial for understanding its pro-oncogenic effects and discovering novel biomarkers.
Purpose of the Study:
- To investigate the role of TGF-β signaling in promoting breast cancer metastasis.
- To identify novel protein biomarkers and pathways associated with TGF-β-mediated metastasis using a proteomic approach.
- To evaluate the efficacy of a TGF-β receptor kinase inhibitor in reducing metastasis.
Main Methods:
- Systemic administration of the TGF-β receptor kinase inhibitor SB-431542 in a mouse model of 4T1 mammary tumor lung metastasis.
- Quantitative proteomic analysis using LTQ Orbitrap Velos coupled with stable isotope dimethyl labeling to compare protein expression in lung metastases from treated and control groups.
- Validation of differentially expressed proteins using western blotting and immunohistochemistry.
Main Results:
- SB-431542 significantly inhibited lung metastasis in mice bearing 4T1 mammary tumors.
- Proteomic analysis identified 4,531 differentially expressed proteins between treated and control groups.
- The eukaryotic initiation factor (eIF) pathway, particularly eIF4A1 and eEF2, was significantly upregulated in control group metastases and identified as a key mediator of TGF-β's tumor-promoting activity.
Conclusions:
- TGF-β signaling plays a critical role in promoting breast cancer lung metastasis.
- Inhibition of TGF-β signaling effectively reduces metastasis and alters the proteomic landscape of metastatic tumors.
- eIF pathway proteins represent novel potential mediators of TGF-β's pro-oncogenic effects and could serve as therapeutic targets or biomarkers.
