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Mediation of wound-related Rous sarcoma virus tumorigenesis by TGF-beta
M H Sieweke1, N L Thompson, M B Sporn
1Cell and Molecular Biology Division, Lawrence Berkeley Laboratory, University of California, Berkeley 94720.
Abstract:
In Rous sarcoma virus (RSV)-infected chickens, wounding leads to tumor formation with nearly 100% frequency in tissues that would otherwise remain tumor-free. Identifying molecular mediators of this phenomenon should yield important clues to the mechanisms involved in RSV tumorigenesis. Immunohistochemical staining showed that TGF-beta is present locally shortly after wounding, but not unwounded controls. In addition, subcutaneous administration of recombinant transforming growth factor-beta 1 (TGF-beta 1) could substitute completely for wounding in tumor induction. A treatment protocol of four doses of 800 nanograms of TGF-beta resulted in v-src-expressing tumors with 100% frequency; four doses of only 10 nanograms still led to tumor formation in 80% of the animals. This effect was specific, as other growth factors with suggested roles in wound healing did not elicit the same response. Epidermal growth factor (EGF) or TGF-alpha had no effect, and platelet-derived growth factor (PDGF) or insulin-like growth factor-1 (IGF-1) yielded only occasional tumors after longer latency. TGF-beta release during the wound-healing response may thus be a critical event that creates a conducive environment for RSV tumorigenesis and may act as a cofactor for transformation in this system.
Insights
Wounding triggers tumor formation in Rous sarcoma virus (RSV)-infected chickens. Transforming growth factor-beta (TGF-beta) released during wound healing acts as a critical cofactor for RSV tumorigenesis.
Area of Science:
- Oncology
- Virology
- Cell Biology
Background:
- Rous sarcoma virus (RSV) infection normally results in tumor formation.
- Wounding specific tissues in RSV-infected chickens dramatically increases tumor incidence.
- Identifying the molecular mechanisms behind wound-induced tumorigenesis is crucial for understanding RSV pathogenesis.
Purpose of the Study:
- To identify molecular mediators responsible for wound-induced tumor formation in RSV-infected chickens.
- To investigate the role of transforming growth factor-beta (TGF-beta) in RSV tumorigenesis.
Main Methods:
- Immunohistochemical staining to detect TGF-beta presence post-wounding.
- Subcutaneous administration of recombinant TGF-beta 1 to assess its tumor-inducing potential.
- Comparison with other growth factors (EGF, TGF-alpha, PDGF, IGF-1) to determine specificity.
Main Results:
- TGF-beta was detected locally after wounding but not in unwounded controls.
- Subcutaneous administration of TGF-beta 1 effectively induced v-src-expressing tumors in a dose-dependent manner.
- Other growth factors like EGF, TGF-alpha, PDGF, and IGF-1 did not induce tumors or had minimal effects.
Conclusions:
- TGF-beta release during wound healing is a critical event promoting RSV tumorigenesis.
- TGF-beta acts as a cofactor for transformation in RSV-infected chickens.
- Targeting TGF-beta signaling could offer therapeutic strategies against RSV-induced tumors.