Targeting of FLT3-ITD kinase contributes to high selectivity of imidazoacridinone C-1311 against FLT3-activated leukemia cells.

Abstract

Drugs targeting receptor tyrosine kinase FLT3 are of particular interest since activating FLT3-internal tandem duplication (ITD) mutations abundantly occur in fatal acute myeloid leukemias (AMLs). Imidazoacridinone C-1311, a DNA-reactive inhibitor of topoisomerase II, has been previously shown to be a potent and selective inhibitor of recombinant FLT3. Here, we expand those findings by studying its effect on leukemia cells with wild-type FLT3, FLT3-ITD mutant and no FLT3 receptor. While brief C-1311 exposure blocked wild-type and FLT3-ITD activity, profound and sustained inhibition was achieved only for FLT3-ITD mutants. C-1311 inhibited FLT3 downstream pathways (MAPK and AKT) independent of FLT3 status, yet translation to decreased viability was significant in FLT3-ITD cells. RNA interference against FLT3-ITD reduced cytotoxic effect and apoptosis induced by C-1311, indicating selective inhibition of FLT3-ITD crucial for high efficacy of drug against activated leukemia cells. Cellular responses in treated FLT3-ITD mutants included G1 and G2/M phase arrest, moderate inhibition of Bcl-2, caspase-3 activation, PARP cleavage, and depolarization of mitochondria. Consistent with selective decrease in FLT3-ITD activity, C-1311 remarkably reduced antiapoptotic survivin mRNA and protein expression, correlating well with enhanced apoptosis of FLT3-ITD cells. No survivin decrease and respectively lower level of apoptosis was found in wild-type and null-FLT3 cells. Combination of C-1311 with cytarabine or doxorubicin again showed distinct synergistic activity in FLT3-ITD-positive cells. The ability of C-1311 to selectively target constitutively active FLT3, suggests a favorable therapeutic index for AML carrying FLT3-ITD mutations. Thus further preclinical and clinical studies addressing its potency against FLT3-ITD kinase is well justified.

• Authors: Anna Skwarska, Ewa Augustin, Michał Beffinger, Anita Wojtczyk, Sonia Konicz, Katarzyna Laskowska, Joanna Polewska
• Journal: Biochemical pharmacology (Biochem Pharmacol) Vol. 95 Issue 4 Pg. 238-52 (Jun 15 2015) ISSN: 1873-2968 [Electronic] England
• PMID: 25896848 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 Elsevier Inc. All rights reserved.

Chemical References

• Aminoacridines
• Antineoplastic Agents
• BIRC5 protein, human
• Inhibitor of Apoptosis Proteins
• RNA, Small Interfering
• Survivin
• Cytarabine
• Doxorubicin
• FLT3 protein, human
• fms-Like Tyrosine Kinase 3
• Caspase 3
• C 1311

Topics

• Aminoacridines (pharmacology)
• Antineoplastic Agents (pharmacology)
• Apoptosis (drug effects)
• Caspase 3 (metabolism)
• Cell Cycle (drug effects)
• Cell Line, Tumor
• Cell Survival (drug effects)
• Cytarabine (pharmacology)
• Doxorubicin (pharmacology)
• Drug Synergism
• Enzyme Activation
• Humans
• Inhibitor of Apoptosis Proteins (metabolism)
• Leukemia, Myeloid, Acute
• Mutation
• Phosphorylation
• RNA, Small Interfering (genetics)
• Signal Transduction
• Survivin
• fms-Like Tyrosine Kinase 3 (genetics, metabolism)