FCX‐146, a potent allosteric inhibitor of Akt kinase in cancer cells: Lead optimization of the second‐generation arylidene indanone scaffold
Meenakshisundaram Balasubramaniam, Naga Rajiv Lakkaniga, Ayed A. Dera, Majed Al Fayi, Mohammed Abohashrh, Irfan Ahmad, Harish C. Chandramoorthy, Nalini Ganesan, Prasanna Rajagopalan
Abstract
Akt, a serine-threonine protein kinase, is regulated by class-I PI3K signaling. Akt regulates a wide variety of cell processes including cell proliferation, survival, and angiogenesis through serine/threonine phosphorylation of downstream targets including mTOR and glycogen-synthase-kinase-3-beta (GSK3β). Targeting cancer-specific overexpression of Akt protein could be an efficient way to control cancer-cell proliferation. However, the ATP-competitive inhibitors are challenged by the highly conserved ATP binding site, and by competition with high cellular concentrations of ATP. We previously developed an allosteric inhibitor, 2-arylidene-4, 7-dimethyl indan-1-one (FXY-1) that showed promising activity against several lung cancer models. In this work, we designed a congeneric series of molecules based on FXY-1 and optimized lead based on computational, in vitro assays. Computational screening followed by enzyme-inhibition and cell-proliferation assays identified a derivative (FCX-146) as a new lead molecule with threefold greater potency than the parent compound. FCX-146 increased apoptosis in HL-60 cells, mediated in part through decreased expression of antiapoptotic Bcl-2 protein and increased levels of Bax-2 and Caspase-3. Molecular-dynamic simulations showed stable binding of FCX-146 to an allosteric (i.e., noncatalytic) pocket in Akt. Together, we propose FCX-146 as a potent second-generation arylidene indanone compound that binds to the allosteric pocket of Akt and potently inhibits its activation.