title: 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.affiliation: Department of Pharmaceutical Technology and Biochemistry, Chemical Faculty, Gdańsk University of Technology, Gdańsk, Poland. Electronic address: anna.skwarska@pg.gda.pl.
authors.forename: Anna
authors.initials: A
authors.lastname: Skwarska
authors.affiliation: Department of Pharmaceutical Technology and Biochemistry, Chemical Faculty, Gdańsk University of Technology, Gdańsk, Poland. Electronic address: ewa.augustin@pg.gda.pl.
authors.forename: Ewa
authors.initials: E
authors.lastname: Augustin
authors.affiliation: Department of Pharmaceutical Technology and Biochemistry, Chemical Faculty, Gdańsk University of Technology, Gdańsk, Poland. Electronic address: beffinger@immunology.uzh.ch.
authors.forename: Michał
authors.initials: M
authors.lastname: Beffinger
authors.affiliation: Department of Pharmaceutical Technology and Biochemistry, Chemical Faculty, Gdańsk University of Technology, Gdańsk, Poland. Electronic address: anita.wojtczyk@gumed.edu.pl.
authors.forename: Anita
authors.initials: A
authors.lastname: Wojtczyk
authors.affiliation: Department of Pharmaceutical Technology and Biochemistry, Chemical Faculty, Gdańsk University of Technology, Gdańsk, Poland. Electronic address: sonia_konicz@yahoo.pl.
authors.forename: Sonia
authors.initials: S
authors.lastname: Konicz
authors.affiliation: Department of Pharmaceutical Technology and Biochemistry, Chemical Faculty, Gdańsk University of Technology, Gdańsk, Poland. Electronic address: klaskowska1987@wp.pl.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Laskowska
authors.affiliation: Department of Pharmaceutical Technology and Biochemistry, Chemical Faculty, Gdańsk University of Technology, Gdańsk, Poland. Electronic address: jpolewska@onet.eu.
authors.forename: Joanna
authors.initials: J
authors.lastname: Polewska
mesh_terms: D000609:Aminoacridines / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003561:Cytarabine / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D004357:Drug Synergism; D004789:Enzyme Activation; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D015470:Leukemia, Myeloid, Acute; D009154:Mutation; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D000077022:Survivin; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics / Q000378:metabolism*
chemical_list: D000609:Aminoacridines; D000970:Antineoplastic Agents; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D034741:RNA, Small Interfering; D000077022:Survivin; D003561:Cytarabine; D004317:Doxorubicin; C497970:FLT3 protein, human; D051941:fms-Like Tyrosine Kinase 3; D053148:Caspase 3; C098965:C 1311
keywords: Acute myeloid leukemia; FLT3; Imidazoacridinone C-1311; Receptor tyrosine kinase; Survivin