title: Cells expressing FLT3/ITD mutations exhibit elevated repair errors generated through alternative NHEJ pathways: implications for genomic instability and therapy.
abstract: The internal tandem duplication (ITD) mutations of the FMS-like tyrosine kinase-3 (FLT3) receptor found in acute myeloid leukemia patients are associated with poor prognosis. Although DNA double-strand breaks (DSBs) are mainly repaired by the DNA-PK-dependent nonhomologous end-joining (NHEJ) pathway in normal mammalian cells, an alternative and less well-defined NHEJ pathway, characterized by microhomology at the repair junctions, play a role in the generation of deletions and translocations leading to cancer progression. Here we report that in FLT3/ITD-expressing cell lines and bone marrow mononuclear cells from FLT3/ITD knock-in mice, end-joining of DSBs occurs at microhomologous sequences resulting in a high frequency of DNA deletions. Strikingly, levels of Ku proteins, key components of the main NHEJ pathway, are decreased in FLT3/ITD(+) cell lines and murine FLT3/ITD bone marrow mononuclear cells. Concomitantly, levels of DNA ligase IIIα, a component of ALT NHEJ, are increased in FLT3/ITD-expressing cells. Cells treated with a FLT3 inhibitor demonstrate decreased DNA ligase IIIα and a reduction in DNA deletions, suggesting that FLT3 signaling regulates the pathways by which DSBs are repaired. Thus, therapy to inhibit FLT3/ITD signaling and/or DNA ligase IIIα may lead to repair that reduces repair errors and genomic instability.
authors.affiliation: Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, USA.
authors.forename: Jinshui
authors.initials: J
authors.lastname: Fan
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Donald
authors.initials: D
authors.lastname: Small
authors.forename: Feyruz
authors.initials: F
authors.lastname: Rassool
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D053903:DNA Breaks, Double-Stranded; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000032:analysis; D004260:DNA Repair; D018450:Disease Progression; D042822:Genomic Instability; D006801:Humans; D055029:Inverted Repeat Sequences; D015470:Leukemia, Myeloid, Acute / Q000235:genetics*; D051379:Mice; D000075223:Poly-ADP-Ribose Binding Proteins; D029867:Xenopus Proteins; D051941:fms-Like Tyrosine Kinase 3 / Q000235:genetics*
chemical_list: D000075223:Poly-ADP-Ribose Binding Proteins; D029867:Xenopus Proteins; C497970:FLT3 protein, human; D051941:fms-Like Tyrosine Kinase 3; D011088:DNA Ligases; D000072481:DNA Ligase ATP; C000618816:DNA ligase III alpha protein, Xenopus
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