TY - JOUR T1 - Proapoptotic Activity and Chemosensitizing Effect of the Novel Akt Inhibitor (2<em>S</em>)-1-(1<em>H</em>-Indol-3-yl)-3-[5-(3-methyl-2<em>H</em>-indazol-5-yl)pyridin-3-yl]oxypropan2-amine (A443654) in T-Cell Acute Lymphoblastic Leukemia JF - Molecular Pharmacology JO - Mol Pharmacol SP - 884 LP - 895 DO - 10.1124/mol.108.047639 VL - 74 IS - 3 AU - Federica Falà AU - William L. Blalock AU - Pier Luigi Tazzari AU - Alessandra Cappellini AU - Francesca Chiarini AU - Giovanni Martinelli AU - Agostino Tafuri AU - James A. McCubrey AU - Lucio Cocco AU - Alberto M. Martelli Y1 - 2008/09/01 UR - http://molpharm.aspetjournals.org/content/74/3/884.abstract N2 - Constitutively activated AKT kinase is a common feature of T-cell acute lymphoblastic leukemia (T-ALL). Here, we report that the novel AKT inhibitor (2S)-1-(1H-indol-3-yl)-3-[5-(3-methyl-2H-indazol-5-yl)pyridin-3-yl]oxypropan2-amine (A443654) leads to rapid cell death of T-ALL lines and patient samples. Treatment of CEM, Jurkat, and MOLT-4 cells with nanomolar doses of the inhibitor led to AKT phosphorylation accompanied by dephosphorylation and activation of the downstream target, glycogen synthase kinase-3β. Effects were time- and dose-dependent, resulting in apoptotic cell death. Treatment of Jurkat cells with A443654 resulted in activation of caspase-2, -3, -6, -8, and -9. Apoptotic cell death was mostly dependent on caspase-2 activation, as demonstrated by preincubation with a selective pharmacological inhibitor. It is remarkable that A443654 was highly effective against the drug-resistant cell line CEM-VBL100, which expresses 170-kDa P-glycoprotein. Moreover, A443654 synergized with the DNA-damaging agent etoposide in both drug-sensitive and drug-resistant cell lines when coadministered [combination index (CI) = 0.39] or when pretreated with etoposide followed by A443654 (CI = 0.689). The efficacy of A443654 was confirmed using blasts from six patients with T-ALL, all of whom displayed low levels of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and constitutive phosphorylation of Akt on Ser473. At 1 μM, the inhibitor was able to induce apoptotic cell death of T-ALL blast cells, as indicated by flow cytometric analysis of samples immunostained for active (cleaved) caspase-3. Because activated AKT is seen in a large percentage of patients with T-ALL, A443654, either alone or in combination with existing drugs, may be a useful therapy for primary and drug-resistant T-ALL. ER -