Internal tandem duplication of FLT3 (FLT3/ITD) induces increased ROS production, DNA damage, and misrepair: implications for poor prognosis in AML.
Activating mutations of the FMS-like tyrosine kinase-3 (FLT3) receptor occur in approximately 30% of acute myeloid leukemia (AML) patients and, at least for internal tandem duplication (ITD) mutations, are associated with poor prognosis. FLT3 mutations trigger downstream signaling pathways including RAS-MAP/AKT kinases and signal transducer and activator of transcription-5 (STAT5). We find that FLT3/ITD mutations start a cycle of genomic instability whereby increased reactive oxygen species (ROS) production leads to increased DNA double-strand breaks (DSBs) and repair errors that may explain aggressive AML in FLT3/ITD patients. Cell lines transfected with FLT3/ITD and FLT3/ITD-positive AML cell lines and primary cells demonstrate increased ROS. Increased ROS levels appear to be produced via STAT5 signaling and activation of RAC1, an essential component of ROS-producing NADPH oxidases. A direct association of RAC1-GTP binding to phosphorylated STAT5 (pSTAT5) provides a possible mechanism for ROS generation. A FLT3 inhibitor blocked increased ROS in FLT3/ITD cells resulting in decreased DSB and increased repair efficiency and fidelity. Our study suggests that the aggressiveness of the disease and poor prognosis of AML patients with FLT3/ITD mutations could be the result of increased genomic instability that is driven by higher endogenous ROS, increased DNA damage, and decreased end-joining fidelity.
Sallmyr
Annahita
A
Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
Fan
Jinshui
J
Datta
Kamal
K
Kim
Kyu-Tae
KT
Grosu
Dan
D
Shapiro
Paul
P
Small
Donald
D
Rassool
Feyruz
F
D020137:Base Pair Mismatch / Q000235:genetics*; D002460:Cell Line; D004249:DNA Damage / Q000235:genetics*; D020440:Gene Duplication; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D011379:Prognosis; D017382:Reactive Oxygen Species / Q000378:metabolism*; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics / Q000378:metabolism*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
D017382:Reactive Oxygen Species; D050799:STAT5 Transcription Factor; C497970:FLT3 protein, human; C497971:Flt3 protein, mouse; D051941:fms-Like Tyrosine Kinase 3; D020830:rac1 GTP-Binding Protein