title: FLT3 and JAK2 Mutations in Acute Myeloid Leukemia Promote Interchromosomal Homologous Recombination and the Potential for Copy Neutral Loss of Heterozygosity.
abstract: Acquired copy neutral LOH (CN-LOH) is a frequent occurrence in myeloid malignancies and is often associated with resistance to standard therapeutic modalities and poor survival. Here, we show that constitutive signaling driven by mutated FLT3 and JAK2 confers interchromosomal homologous recombination (iHR), a precedent for CN-LOH. Using a targeted recombination assay, we determined significant iHR activity in internal tandem duplication FLT3 (FLT3-ITD) and JAK2V617F-mutated cells. Sister chromatid exchanges, a surrogate measure of iHR, was significantly elevated in primary FLT3-ITD normal karyotype acute myeloid leukemia (NK-AML) compared with wild-type FLT3 NK-AML. HR was harmonized to S phase of the cell cycle to repair broken chromatids and prevent iHR. Increased HR activity in G0arrested primary FLT3-ITD NK-AML in contrast to wild-type FLT3 NK-AML. Cells expressing mutated FLT3-ITD demonstrated a relative increase in mutation frequency as detected by thymidine kinase (TK) gene mutation assay. Moreover, resistance was associated with CN-LOH at the TK locus. Treatment of FLT3-ITD- and JAK2V617F-mutant cells with the antioxidantN-acetylcysteine diminished reactive oxygen species (ROS), restoring iHR and HR levels. Our findings show that mutated FLT3-ITD and JAK2 augment ROS production and HR, shifting the cellular milieu toward illegitimate recombination events such as iHR and CN-LOH. Therapeutic reduction of ROS may thus prevent leukemic progression and relapse in myeloid malignancies.Cancer Res; 77(7); 1697-708. ©2017 AACR.
authors.affiliation: Department of Haematological Medicine, King's College London, Leukaemia Sciences Laboratories, The Rayne Institute, London, United Kingdom.
authors.forename: Terry J
authors.initials: TJ
authors.lastname: Gaymes
authors.affiliation: Department of Haematological Medicine, King's College London, Leukaemia Sciences Laboratories, The Rayne Institute, London, United Kingdom.
authors.forename: Azim
authors.initials: A
authors.lastname: Mohamedali
authors.affiliation: Department of Haematological Medicine, King's College London, Leukaemia Sciences Laboratories, The Rayne Institute, London, United Kingdom.
authors.forename: Anthony L
authors.initials: AL
authors.lastname: Eiliazadeh
authors.affiliation: Department of Haematological Medicine, King's College London, Leukaemia Sciences Laboratories, The Rayne Institute, London, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Darling
authors.affiliation: Department of Haematological Medicine, King's College London, Leukaemia Sciences Laboratories, The Rayne Institute, London, United Kingdom. ghulam.mufti@kcl.ac.uk.
authors.forename: Ghulam J
authors.initials: GJ
authors.lastname: Mufti
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D045744:Cell Line, Tumor; D002648:Child; D059765:Homologous Recombination; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics*; D015470:Leukemia, Myeloid, Acute / Q000235:genetics* / Q000378:metabolism; D019656:Loss of Heterozygosity; D008875:Middle Aged; D009154:Mutation; D051135:Rad51 Recombinase / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D012854:Sister Chromatid Exchange; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics*
chemical_list: D017382:Reactive Oxygen Species; C497970:FLT3 protein, human; D051941:fms-Like Tyrosine Kinase 3; C507924:JAK2 protein, human; D053614:Janus Kinase 2; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D000111:Acetylcysteine