Polysaccharides derived from Lycium barbarum suppress IGF-1-induced angiogenesis via PI3K/HIF-1α/VEGF signalling pathways in MCF-7 cells

Lycium barbarum (LB) is a berry-type fruit. Lycium barbarum polysaccharides (LBPs), derived from LB, has anti-tumour properties and exhibits potent anti-angiogenic effects. The aim of this study was to elucidate possible signal transduction pathways functioning to mediate the breast cancer-suppressive effects of LBPs. Using MCF-7 cells, we determined that a 90 h treatment with 0.50 mg/ml of LBPs resulted in significant inhibition of cell proliferation. Using this same system, we observed that LBPs could also affect insulin-like growth factor (IGF)-1 protein accumulation, suppress phosphatidylinositol 3-kinase (PI3K) activity and phosphorylated-PI3K (p-PI3K) protein levels, inhibit hypoxia-inducible factor-1 (HIF-1α) protein accumulation without altering HIF-1α mRNA levels, and suppress VEGF mRNA expression and protein production. Our results demonstrate that LBPs may inhibit tumour cell growth by suppressing IGF-1-induced angiogenesis via PI3K/HIF-1α/VEGF signalling pathways.