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Updated: May 17, 2026
Molecular and Immunologic Techniques in a Genetically Engineered Mouse Model of Gastrointestinal Stromal Tumor
Published on: May 2, 2022
Production of gastrointestinal tumors in mice by modulating latent TGF-β1 activation
Kotaro Shibahara1, Mitsuhiko Ota, Masahito Horiguchi
1Department of Cell Biology, New York University Langone School of Medicine, New York, NY 10016, USA.
Abstract:
TGF-β and its signaling pathways are important mediators in the suppression of cancers of the gastrointestinal tract. TGF-β is released from cells in a latent complex consisting of TGF-β, the TGF-β propeptide [latency associated protein (LAP)], and a latent TGF-β binding protein (LTBP). We previously generated mice in which the LTBP-binding cysteine residues in LAP TGF-β1 were mutated to serine precluding covalent interactions with LTBP. These Tgfb1(C33S/C33S) mice develop multiorgan inflammation and tumors consistent with reduced TGF-β1 activity. To test whether further reduction in active TGF-β levels would yield additional tumors and a phenotype more similar to Tgfb1(-/-) mice, we generated mice that express TGF-β1(C33S) and are deficient in either integrin β8 or TSP-1, known activators of latent TGF-β1. In addition, we generated mice that have one mutant allele and one null allele at the Tgfb1 locus, reasoning that these mice should synthesize half the total amount of TGF-β1 as Tgfb1(C33S/C33S) mice, and the amount of active TGF-β1 would be correspondingly decreased compared with Tgfb1(C33S/C33S) mice. These compound-mutant mice displayed more severe inflammation and higher tumor numbers than the parental Tgfb1(C33S/C33S) animals. The level of active TGF-β1 in compound mutant mice seemed to be decreased compared with Tgfb1(C33S/C33S) mice as determined from analyses of surrogate markers of active TGF-β, such as P-Smad2, C-Myc, KI-67, and markers of cell-cycle traverse. We conclude that these mutant mice provide a useful system for modulating TGF-β levels in a manner that determines tumor number and inflammation within the gastrointestinal tract.
Insights
Reducing active TGF-β1 levels in mice by further genetic modification led to increased inflammation and tumor development in the gastrointestinal tract. These findings highlight TGF-β1
Area of Science:
- Oncology
- Immunology
- Molecular Biology
Background:
- Transforming Growth Factor-beta (TGF-β) signaling is crucial for suppressing gastrointestinal cancers.
- TGF-β is released in a latent complex involving latency associated protein (LAP) and latent TGF-β binding protein (LTBP).
- Previous studies generated Tgfb1(C33S/C33S) mice with mutated LAP, exhibiting inflammation and tumors due to reduced TGF-β1 activity.
Purpose of the Study:
- To investigate if further reducing active TGF-β1 levels in mice enhances tumor development and mimics Tgfb1(-/-) phenotypes.
- To explore the role of integrin β8 and TSP-1 as TGF-β1 activators in vivo.
- To establish a mouse model for modulating TGF-β1 levels and studying their impact on gastrointestinal inflammation and tumorigenesis.
Main Methods:
- Generated compound-mutant mice by combining TGF-β1(C33S) mutation with deficiencies in integrin β8 or TSP-1.
- Created mice with one mutant allele and one null allele at the Tgfb1 locus to reduce total TGF-β1 synthesis by half.
- Assessed inflammation and tumor development, and analyzed surrogate markers of active TGF-β1 (P-Smad2, C-Myc, KI-67) to determine active TGF-β1 levels.
Main Results:
- Compound-mutant mice exhibited more severe inflammation and higher tumor burdens compared to Tgfb1(C33S/C33S) mice.
- Surrogate marker analyses suggested decreased active TGF-β1 levels in compound mutant mice relative to Tgfb1(C33S/C33S) mice.
- The degree of inflammation and tumor number correlated with the modulated levels of active TGF-β1.
Conclusions:
- Further reduction of active TGF-β1 levels exacerbates inflammation and increases tumor incidence in the gastrointestinal tract.
- The developed compound-mutant mouse models offer a valuable system for studying the quantitative relationship between TGF-β1 levels and disease phenotypes.
- Modulating TGF-β1 activity through genetic manipulation provides insights into cancer suppression mechanisms and potential therapeutic strategies.
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