Developments in selective small molecule ATP-targeting the serine/threonine kinase Akt/PKB.
ABSTRACT The serine/threonine kinase Akt, also known as protein kinase B (PKB), plays a key role in cell survival and proliferation through a number of downstream effectors. Recent studies indicate that unregulated activation of the Phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a prominent feature of many human cancers and Akt is overexpressed or activated in all major cancers. For these reasons, Akt is considered as an attractive target for cancer therapy. In the past few years, several series of compounds with diverse structural features have been reported as Akt inhibitors, such as, ATP-competitive inhibitors, Phosphatidylinositol (PI) analogs, and allosteric inhibitors. Although most of the inhibitors exhibited potent inhibitory activities at nanomolar concentrations against Akt, some of them have shown unfavorable selectivity against other protein kinases especially PKA and PKC. This review will focus on the recent advances in the development and biological evaluation of selective ATP-competitive inhibitors for Akt. We will summarize the novel approaches toward the developments of selective ATP-competitive inhibitors, expecting to give information to design new ATP-competitive inhibitors with high selectivity, bioavailability, and potency.
Article: Pleckstrin homology domain of akt kinase: a proof of principle for highly specific and effective non-enzymatic anti-cancer target.[show abstract] [hide abstract]
ABSTRACT: While pharmacological inhibition of Akt kinase has been regarded as a promising anti-cancer strategy, most of the Akt inhibitors that have been developed are enzymatic inhibitors that target the kinase active site of Akt. Another key cellular regulatory event for Akt activation is the translocation of Akt kinase to the cell membrane from the cytoplasm, which is accomplished through the pleckstrin homology (PH) domain of Akt. However, compounds specifically interacting with the PH domain of Akt to inhibit Akt activation are currently limited. Here we identified a compound, lancemaside A (LAN-A), which specifically binds to the PH domain of Akt kinase. First, our mass spectra analysis of cellular Akt kinase isolated from cells treated with LAN-A revealed that LAN-A specifically binds to the PH domain of cellular Akt kinase. Second, we observed that LAN-A inhibits the translocation of Akt kinase to the membrane and thus Akt activation, as examined by the phosphorylation of various downstream targets of Akt such as GSK3β, mTOR and BAD. Third, in a co-cultured cell model containing human lung epithelial cancer cells (A549) and normal human primary lung fibroblasts, LAN-A specifically restricts the growth of the A549 cells. LAN-A also displayed anti-proliferative effects on various human cancer cell lines. Finally, in the A549-luciferase mouse transplant model, LAN-A effectively inhibited A549 cell growth with little evident cytotoxicity. Indeed, the therapeutic index of LAN-A in this mouse model was >250, supporting that LAN-A is a potential lead compound for PH domain targeting as a safe anti-cancer Akt inhibitor.PLoS ONE 01/2012; 7(11):e50424. · 4.09 Impact Factor