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.

Abstract

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-3beta. 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 microM, 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.

• Authors: Federica Falà, William L Blalock, Pier Luigi Tazzari, Alessandra Cappellini, Francesca Chiarini, Giovanni Martinelli, Agostino Tafuri, James A McCubrey, Lucio Cocco, Alberto M Martelli
• Journal: Molecular pharmacology (Mol Pharmacol) Vol. 74 Issue 3 Pg. 884-95 (Sep 2008) ISSN: 1521-0111 [Electronic] United States
• PMID: 18577685 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• A 443654
• Indazoles
• Indoles
• Phosphothreonine
• Phosphoserine
• Etoposide
• GSK3B protein, human
• Glycogen Synthase Kinase 3 beta
• Proto-Oncogene Proteins c-akt
• Glycogen Synthase Kinase 3
• Caspases

Topics

• 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, pathology)
• Phosphorylation (drug effects)
• Phosphoserine (metabolism)
• Phosphothreonine (metabolism)
• Proto-Oncogene Proteins c-akt (antagonists & inhibitors)