Inhibition of tyrosine phosphorylation of vascular endothelial growth factor receptors in human umbilical vein endothelial cells: a potent anti-angiogenic lipid-rich extract from shark.

We have previously reported that an ethanolic extract of dried shark muscle mixed with olive oil (shark muscle-olive oil [SMO]) has potent anti-angiogenic activity and that this extract appears to inhibit the binding of vascular endothelial growth factor (VEGF) to its receptor(s). In this study, we investigated the effects of SMO on the phosphorylation of VEGF receptor(s) in human umbilical vein endothelial cells (HUVECs). In vitro cell proliferation assays showed that SMO significantly reversed the VEGF-promoted increase in HUVEC proliferation. Western blot analysis revealed that SMO treatment markedly inhibited the VEGF-promoted tyrosine phosphorylation of VEGF receptor-2 (KDR) and VEGF receptor-1 (Flt-1) in a dose-dependent manner. These results demonstrated that SMO might interfere with or block the binding of VEGF with its receptors, and thereby inhibit the VEGF receptor(s) signal transduction pathway and so inhibit angiogenesis.