Antitumor and anti-angiogenic activities of Scutellaria barbata extracts in vitro are partially mediated by inhibition of Akt/protein kinase B.

The Akt pathway is considered a pivotal player in regulating cell survival, growth, migration and angiogenesis. Disruption of normal Akt/PKB/PTEN signaling frequently occurs in numerous types of human cancers. Therefore, this signaling pathway is regarded as an important target for effective cancer therapeutic strategies. In the present study, methanol extracts from Scutellaria barbata (S. barbata) were determined to be Akt/protein kinase B inhibitory, after screening a panel of 40 traditional Chinese herbs with the Fast Activated Cell-based ELISA (FACE) assay. S. barbata extracts were found to suppress the phosphorylation levels of Akt. This inhibition was Akt kinase-specific as it had no effect on PI3K, the upstream kinase of Akt, whereas the levels of phosphorylated Bad and FHKR, the two downstream targets of Akt, changed as the levels of Akt changed. S. barbata extracts also exhibited cytotoxicity against LoVo and human umbilical vein endothelial cells (HUVECs). Furthermore, this extract inhibited the process of in vitro angiogenesis of HUVECs on Matrigel. S. barbata may be a suitable alternative source with which to isolate small molecules for use as Akt kinase inhibitors.