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Suppression of thrombospondin-1 expression during uveal melanoma progression and its potential therapeutic utility
Shoujian Wang1, Aneesh Neekhra, Daniel M Albert
1Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-4673, USA.
Objectives:
To determine whether expression of thrombospondin-1 (TSP1), an endogenous inhibitor of angiogenesis, is downregulated during progression of uveal melanoma and whether administration of TSP1 and/or its antiangiogenic peptides attenuate tumor growth.
Methods:
Tyrosinase-SV40 T-antigens (Tyr Tag) transgenic mice were used for evaluation of TSP1 expression during tumor progression using immunohistological methods. The therapeutic potential of TSP1 on tumor progression was evaluated either by crossing Tyr Tag mice with a line of transgenic mice overexpressing TSP1 in the eye or by administration of TSP1-mimetic peptide with known antiangiogenic, antitumor activity. Tumor areas were measured in histological sections using Optima software (Media Cybernetics, Inc).
Results:
The Tyr Tag tumors from 3-week-old mice showed significant TSP1 expression, which was dramatically downregulated in tumors from 12-week-old mice. Furthermore, the development and progression of tumor was significantly delayed in Tyr Tag TSP1 transgenic mice or Tyr Tag mice receiving TSP1-mimetic peptide (100 mg/kg/d).
Conclusions:
Expression of TSP1 was decreased with the angiogenic switch during progression of uveal melanoma, and TSP1 and/or its antiangiogenic peptides were effective in attenuation of tumor growth.
Clinical Relevance:
Modulation of TSP1 expression and/or activity may be beneficial in treating uveal melanoma.
Insights
Thrombospondin-1 (TSP1) expression decreases in uveal melanoma as it progresses. Restoring TSP1 or using its peptides effectively slowed tumor growth, suggesting therapeutic potential.
Area of Science:
- Ophthalmology
- Oncology
- Molecular Biology
Background:
- Uveal melanoma is an ocular cancer where angiogenesis plays a key role.
- Thrombospondin-1 (TSP1) is an endogenous inhibitor of angiogenesis.
- Understanding TSP1's role in uveal melanoma progression is crucial for developing new therapies.
Purpose of the Study:
- To investigate the expression levels of TSP1 during uveal melanoma progression.
- To evaluate the therapeutic efficacy of TSP1 and its peptides in attenuating uveal melanoma growth.
Main Methods:
- Utilized Tyrosinase-SV40 T-antigens (Tyr Tag) transgenic mice to study TSP1 expression via immunohistology.
- Assessed TSP1's therapeutic potential by crossing Tyr Tag mice with TSP1-overexpressing transgenic mice or administering a TSP1-mimetic peptide.
- Quantified tumor areas using Optima software on histological sections.
Main Results:
- TSP1 expression was significantly downregulated in established Tyr Tag tumors compared to early-stage tumors.
- Tumor development and progression were markedly delayed in Tyr Tag mice with elevated TSP1 or treated with TSP1-mimetic peptide.
Conclusions:
- TSP1 expression diminishes during the angiogenic switch in uveal melanoma progression.
- TSP1 and its antiangiogenic peptides demonstrated effectiveness in reducing tumor growth.
- Modulating TSP1 expression or activity presents a promising strategy for uveal melanoma treatment.
