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Angiopoietin-2 Levels Are Associated with Disease Progression in Metastatic Malignant Melanoma
Ist Teil von
Clinical cancer research, 2009-02, Vol.15 (4), p.1384-1392
Ort / Verlag
Philadelphia, PA: American Association for Cancer Research
Erscheinungsjahr
2009
Link zum Volltext
Quelle
Free E-Journal (出版社公開部分のみ)
Beschreibungen/Notizen
Purpose: The blood vessel-destabilizing Tie2 ligand angiopoietin-2 (Ang-2) acts in concert with the vascular endothelial growth factor/vascular
endothelial growth factor receptor system to control vessel assembly during tumor progression. We hypothesized that circulating
soluble Ang-2 (sAng-2) may be involved in melanoma progression.
Experimental Design: Serum samples ( n = 98) from melanoma patients (American Joint Committee on Cancer stages I-IV), biopsies of corresponding patients, and human
melanoma cell lines were analyzed for expression of Ang-2 and S100β. Multiple sera of a subcohort of 33 patients were tested
during progression from stage III to IV. Small interfering RNA-based loss-of-function experiments were done to assess effects
of Ang-2 on melanoma cells.
Results: Circulating levels of sAng-2 correlate with tumor progression in melanoma patients ( P < 0.0001) and patient survival ( P = 0.007). Analysis of serum samples during the transition from stage III to IV identified an increase of sAng-2 up to 400%.
Comparative analyses revealed a 56% superiority of sAng-2 as predictive marker over the established marker S100β. Immunohistochemistry
and reverse transcription-PCR confirmed the prominent expression of Ang-2 by tumor-associated endothelial cells but identified
Ang-2 also as a secreted product of melanoma cells themselves. Corresponding cellular experiments revealed that human melanoma-isolated
tumor cells were Tie2 positive and that Ang-2 acted as an autocrine regulator of melanoma cell migration and invasion.
Conclusions: The experiments establish sAng-2 as a biomarker of melanoma progression and metastasis correlating with tumor load and overall
survival. The identification of an autocrine angiopoietin/Tie loop controlling melanoma migration and invasion warrants further
functional experiments and validate the angiopoietin/Tie system as a promising therapeutic target for human melanomas.