Anti-angiogenic effect of a chemically sulfated polysaccharide from Phellinus ribis by inhibiting VEGF/VEGFR pathway

Previous studies have demonstrated that the sulfated polysaccharide named PRP-S16 could inhibit the proliferation, migration, and tube formation of endothelial cells in vitro. Here, its anti-angiogenic effect and mechanism in vivo were investigated by Lewis lung carcinoma (LLC) mice model. PRP-S16 significantly reduced the microvessel density (MVD) of tumor, exhibiting a high tumor growth inhibitory effect in LLC mice. All designed assays including quantitative real-time PCR, immunohistochemistry, enzyme-linked immunosorbent assay and western blotting showed that PRP-S16 reduced the mRNA and the protein expression of vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2) in serum or tumor tissue of mice. Western blotting also detected decreased phosphorylated (p)-VEGFR-1, p-VEGFR-2, hypoxia-inducible factor-1α (HIF-1α), protein kinase B (Akt), and matrix metalloproteinases-9 (MMP-9). PRP-S16 had no adverse effects on angiogenesis in non-target organs. These findings suggested that the mechanism of anti-angiogenesis of PRP-S16 in vivo was due to inhibition of VEGF/VEGFR signaling pathway and it might be a promising candidate for tumor by anti-angiogenic therapy.