title: Internal tandem duplication of FLT3 deregulates proliferation and differentiation and confers resistance to the FLT3 inhibitor AC220 by Up-regulating RUNX1 expression in hematopoietic cells.
abstract: Internal tandem duplication in the FLT3 gene (FLT3/ITD), which is found in patients with acute myeloid leukemia (AML), causes resistance to FLT3 inhibitors. We found that RUNX1, a transcription factor that regulates normal hematopoiesis, is up-regulated in patients with FLT3/ITD(+) AML. While RUNX1 can function as a tumor suppressor, recent data have shown that RUNX1 is required for AML cell survival. In the present study, we investigated the functional role of RUNX1 in FLT3/ITD signaling. FLT3/ITD induced growth factor-independent proliferation and impaired G-CSF mediated myeloid differentiation in 32D hematopoietic cells, coincident with up-regulation of RUNX1 expression. Silencing of RUNX1 expression significantly decreased proliferation and secondary colony formation, and partially abrogated the impaired myeloid differentiation of FLT3/ITD(+) 32D cells. Although the number of FLT3/ITD(+) 32D cells declined after incubation with the FLT3/ITD inhibitor AC220, the cells became refractory to AC220, concomitant with up-regulation of RUNX1. Silencing of RUNX1 abrogated the emergence and proliferation of AC220-resistant FLT3/ITD(+) 32D cells in the presence of AC220. Our data indicate that FLT3/ITD deregulates cell proliferation and differentiation and confers resistance to AC220 by up-regulating RUNX1 expression. These findings suggest an oncogenic role for RUNX1 in FLT3/ITD(+) cells and that inhibition of RUNX1 function represents a potential therapeutic strategy in patients with refractory FLT3/ITD(+) AML.
authors.affiliation: Department of Pediatrics, Shimane University School of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan. hirade25@med.shimane-u.ac.jp.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Hirade
authors.affiliation: Department of Pediatrics, Shimane University School of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Abe
authors.affiliation: Department of Oncology/Hematology, Shimane University School of Medicine, Izumo, Japan.
authors.forename: Chie
authors.initials: C
authors.lastname: Onishi
authors.affiliation: Department of Pediatrics, Shimane University School of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan.|Division of Blood Transfusion, Shimane University School of Medicine, Izumo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Taketani
authors.affiliation: Department of Pediatrics, Shimane University School of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Department of Pediatrics, Shimane University School of Medicine, 89-1 Enya-cho, Izumo, Shimane, 693-8501, Japan. sfukuda@med.shimane-u.ac.jp.
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukuda
mesh_terms: D000818:Animals; D052160:Benzothiazoles / Q000494:pharmacology*; D002454:Cell Differentiation / Q000235:genetics*; D049109:Cell Proliferation / Q000235:genetics*; D002478:Cells, Cultured; D050676:Core Binding Factor Alpha 2 Subunit / Q000235:genetics* / Q000502:physiology; D020440:Gene Duplication / Q000235:genetics; D015870:Gene Expression; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000628:therapy; D051379:Mice; D058990:Molecular Targeted Therapy; D010671:Phenylurea Compounds / Q000494:pharmacology*; D020080:Tandem Repeat Sequences; D015854:Up-Regulation; D051941:fms-Like Tyrosine Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000502:physiology
chemical_list: D052160:Benzothiazoles; D050676:Core Binding Factor Alpha 2 Subunit; D010671:Phenylurea Compounds; C493728:RUNX1 protein, human; C544967:quizartinib; C497970:FLT3 protein, human; D051941:fms-Like Tyrosine Kinase 3
keywords: AC220; AML; FLT3/ITD; RUNX1