title: FLT3-ITD confers resistance to the PI3K/Akt pathway inhibitors by protecting the mTOR/4EBP1/Mcl-1 pathway through STAT5 activation in acute myeloid leukemia.
abstract: FLT3-ITD and FLT3-TKD are the most frequent tyrosine kinase mutations in acute myeloid leukemia (AML), with the former associated with poor prognosis. Here, we show that the PI3K inhibitor GDC-0941 or the Akt inhibitor MK-2206 induced apoptosis through the mitochondria-mediated intrinsic pathway more efficiently in hematopoietic 32D cells driven by FLT3-TKD (32D/TKD) than FLT3-ITD (32D/ITD), which robustly activated STAT5. The resistance to GDC-0941 and MK-2206 was gained by expression of the constitutively activated STAT5 mutant STAT5A1*6 in 32D/TKD cells, while it was abrogated by the STAT5 inhibitor pimozide in 32D/ITD cells or FLT3-ITD-expressing human leukemic MV4-11 cells. GDC-0941 or MK-2206 induced dephosphorylation of 4EBP1 more conspicuously in 32D/TKD than in 32D/ITD, which was prevented or augmented by STAT5A1*6 or pimozide, respectively, and correlated with downregulation of the eIF4E/eIF4G complex formation and Mcl-1 expression. Furthermore, exogenous expression of Mcl-1 endowed resistance to GDC-0941 and MK-2206 on 32D/TKD cells. Finally, it was confirmed in primary AML cells with FLT3-ITD that pimozide enhanced 4EBP1 dephosphorylation and Mcl-1 downregulation to augment cytotoxicity of GDC-0941. These data suggest that the robust STAT5 activation by FLT3-ITD protects cells treated with the PI3K/Akt pathway inhibitors from apoptosis by maintaining Mcl-1 expression through the mTORC1/4EBP1/eIF4E pathway.
authors.affiliation: Department of Hematology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nogami
authors.affiliation: Department of Hematology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Gaku
authors.initials: G
authors.lastname: Oshikawa
authors.affiliation: Department of Hematology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Keigo
authors.initials: K
authors.lastname: Okada
authors.affiliation: Department of Hematology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Shusaku
authors.initials: S
authors.lastname: Fukutake
authors.affiliation: Department of Hematology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Umezawa
authors.affiliation: Department of Hematology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Toshikage
authors.initials: T
authors.lastname: Nagao
authors.affiliation: Department of Hematology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kurosu
authors.affiliation: Department of Hematology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Miura
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D004789:Enzyme Activation; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism; D039642:Eukaryotic Initiation Factors; D006575:Heterocyclic Compounds, 3-Ring / Q000494:pharmacology; D006801:Humans; D007191:Indazoles / Q000494:pharmacology; D015470:Leukemia, Myeloid, Acute / Q000473:pathology*; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D010868:Pimozide / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors; D050799:STAT5 Transcription Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D051941:fms-Like Tyrosine Kinase 3 / Q000378:metabolism*
chemical_list: C532162:2-(1H-indazol-4-yl)-6-(4-methanesulfonylpiperazin-1-ylmethyl)-4-morpholin-4-ylthieno(3,2-d)pyrimidine; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C499527:Eif4ebp1 protein, mouse; C491908:Eif4g1 protein, mouse; D039561:Eukaryotic Initiation Factor-4E; D039603:Eukaryotic Initiation Factor-4G; D039642:Eukaryotic Initiation Factors; D006575:Heterocyclic Compounds, 3-Ring; D007191:Indazoles; C548887:MK 2206; C579094:Mcl1 protein, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010750:Phosphoproteins; D050799:STAT5 Transcription Factor; C494093:Stat5a protein, mouse; D013449:Sulfonamides; C000601282:eIF4E protein, mouse; D010868:Pimozide; C546843:mTOR protein, mouse; C497971:Flt3 protein, mouse; D051941:fms-Like Tyrosine Kinase 3; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D053453:Caspase 9
keywords: AML; FLT3; MCL-1; PI3K; STAT5
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