Anti-angiogenic effects of resveratrol mediated by decreased VEGF and increased TSP1 expression in melanoma-endothelial cell co-culture.

Resveratrol, a naturally occurring polyphenol, has been reported to be an anti-tumor and chemopreventive agent. Recent data show that it may also exert anti-angiogenic effects. We hypothesized that the anti-angiogenic activity of resveratrol may be caused by modulation of tumor cell release of thrombospondin-1 (TSP1) and vascular endothelial growth factor (VEGF) into the extracellular matrix, leading to vascular endothelial cell (VEC) apoptosis. We therefore evaluated the effects of resveratrol on melanoma cell lines co-cultured with vascular endothelial cells in monolayer and in three dimensional spheroids. We found that resveratrol stimulated isolated VEC proliferation, while it caused growth inhibition of VECs grown with melanoma cells in three-dimensional co-culture. This effect was associated with increased melanoma cell expression of tumor suppressor protein 53 and matrix protein TSP1, as well as decreased hypoxia-driven expression of hypoxia inducible factor-1α and inhibition of VEGF production.