Proapoptotic Activity and Chemosensitizing Effect of the Novel Akt Inhibitor (2S)-1-(1H-Indol-3-yl)-3-[5-(3-methyl-2H-indazol-5-yl)pyridin-3-yl]oxypropan2-amine (A443654) in T-Cell Acute Lymphoblastic Leukemia

• Published in: Molecular pharmacology 2008-09, Vol.74 (3), p.884-895
• Main Authors: Falà, Federica, Blalock, William L, Tazzari, Pier Luigi, Cappellini, Alessandra, Chiarini, Francesca, Martinelli, Giovanni, Tafuri, Agostino, McCubrey, James A, Cocco, Lucio, Martelli, Alberto M
• Format: Article
• Language: English
• Subjects: Apoptosis - drug effects; Caspases - metabolism; Cell Line, Tumor; Cell Proliferation - drug effects; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm - drug effects; Drug Screening Assays, Antitumor; Drug Synergism; Enzyme Activation - drug effects; Etoposide - pharmacology; Glycogen Synthase Kinase 3 - metabolism; Glycogen Synthase Kinase 3 beta; Humans; Indazoles - pharmacology; Indoles - pharmacology; Leukemia-Lymphoma, Adult T-Cell - enzymology; Leukemia-Lymphoma, Adult T-Cell - pathology; Phosphorylation - drug effects; Phosphoserine - metabolism; Phosphothreonine - metabolism; Proto-Oncogene Proteins c-akt - antagonists & inhibitors
• ISSN: 0026-895X; 1521-0111
• DOI: 10.1124/mol.108.047639

Constitutively activated AKT kinase is a common feature of T-cell acute lymphoblastic leukemia (T-ALL). Here, we report that the novel AKT inhibitor (2 S )-1-(1 H -indol-3-yl)-3-[5-(3-methyl-2 H -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.