Wilfoside K1N isolated from Cynanchum wilfordii inhibits angiogenesis and tumor cell invasion.

Wilfoside K1N is a polyoxypregnane glycoside isolated from Cynanchum wilfordii (Asclepiadaceae). Polyoxypregnane glycosides are associated with cellular immunity and anti-tumor activity, and increase the cytotoxicity of many anti-cancer drugs showing multidrug resistant activity on tumor cells. In the present study, we investigated the anti-angiogenic and anti-invasive activities of wilfoside K1N. In in vivo Matrigel plug assay using C57BL/6 mice, wilfoside K1N strongly inhibited basic fibroblast growth factor-induced microvessel formation. Exposure of wilfoside K1N to human umbilical vein endothelial cells (HUVEC) suppressed in vitro tube formation at a concentration not affecting cell viability. Moreover, wilfoside K1N significantly reduced the proliferation of HUVEC and calf pulmonary artery endothelial cells. In addition, wilfoside K1N decreased in vitro invasion of HT1080 human fibrosarcoma cells, and the inhibition might be through down-regulation of activity as well as quantity of matrix metalloproteinase-9. Therefore, our present study suggests that wilfoside K1N may have a potential to have strong anti-angiogenic and anti-invasive activities both in vitro and in vivo.