Solanum nigrum Suppress Angiogenesis-Mediated Tumor Growth Through Inhibition of the AKT/mTOR Pathway.

Solanum nigrum L., an edible plant and local dish, has been assigned anticancer activities. However, the anticancer mechanisms of S. nigrum are poorly understood. Here, we investigated whether the water or polyphenol extracts of S. nigrum (SNWE or SNPE) could inhibit angiogenesis-mediated tumor growth. In nude mice bearing tumor xenografts, SNWE or SNPE significantly reduced the volume and weight of the tumors, and decreased the expression of CD31, a marker for angiogenesis. SNWE or SNPE was found to inhibit the VEGF-induced capillary structure formation of endothelial cells. The chicken egg chorioallantoic membrane (CAM) and matrigel plug assays showed further that SNWE or SNPE inhibited tumor angiogenesis. In human umbilical vascular endothelial cells (HUVECs), SNWE or SNPE suppressed the VEGF-induced activation of AKT and mTOR. Moreover, SNWE or SNPE inhibited the viability of human hepatoma HepG2 cells, and these effects were correlated with the extent of inhibition of the AKT/mTOR pathway. Taken together, our data imply that SNWE or SNPE downregulated the AKT/mTOR pathway in HUVECs and HepG2 cells, which lead to reduced tumor growth and angiogenesis.