title: Transposon Mutagenesis Reveals Fludarabine Resistance Mechanisms in Chronic Lymphocytic Leukemia.
abstract: OBJECTIVE
  To identify resistance mechanisms for the chemotherapeutic drug fludarabine in chronic lymphocytic leukemia (CLL), as innate and acquired resistance to fludarabine-based chemotherapy represents a major challenge for long-term disease control.
  
  
  METHODS
  We used piggyBac transposon-mediated mutagenesis, combined with next-generation sequencing, to identify genes that confer resistance to fludarabine in a human CLL cell line.
  
  
  RESULTS
  In total, this screen identified 782 genes with transposon integrations in fludarabine-resistant pools of cells. One of the identified genes is a known resistance mediator DCK (deoxycytidine kinase), which encodes an enzyme that is essential for the phosphorylation of the prodrug to the active metabolite. BMP2K, a gene not previously linked to CLL, was also identified as a modulator of response to fludarabine. In addition, 10 of 782 transposon-targeted genes had previously been implicated in treatment resistance based on somatic mutations seen in patients refractory to fludarabine-based therapy. Functional characterization of these genes supported a significant role for ARID5B and BRAF in fludarabine sensitivity. Finally, pathway analysis of transposon-targeted genes and RNA-seq profiling of fludarabine-resistant cells suggested deregulated MAPK signaling as involved in mediating drug resistance in CLL.
  
  
  CONCLUSIONS
  To our knowledge, this is the first forward genetic screen for chemotherapy resistance in CLL. The screen pinpointed novel genes and pathways involved in fludarabine resistance along with previously known resistance mechanisms. Transposon screens can therefore aid interpretation of cancer genome sequencing data in the identification of genes modifying sensitivity to chemotherapy. Clin Cancer Res; 22(24); 6217-27. ©2016 AACR.
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Pandzic
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Jimmy
authors.initials: J
authors.lastname: Larsson
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Liqun
authors.initials: L
authors.lastname: He
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Snehangshu
authors.initials: S
authors.lastname: Kundu
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.|Department of Biochemistry, Yong Loo Lin School of Medicine, NUS, Institute of Molecular and Cell Biology, A*STAR, Singapore.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Ban
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Akhtar-Ali
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Anders R
authors.initials: AR
authors.lastname: Hellström
authors.affiliation: Radcliffe Department of Medicine, Oxford University, Oxford, United Kingdom.
authors.forename: Anna
authors.initials: A
authors.lastname: Schuh
authors.affiliation: Radcliffe Department of Medicine, Oxford University, Oxford, United Kingdom.
authors.forename: Ruth
authors.initials: R
authors.lastname: Clifford
authors.affiliation: Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Blakemore
authors.affiliation: Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Strefford
authors.affiliation: Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: Tycho
authors.initials: T
authors.lastname: Baumann
authors.affiliation: Servicio de Hematología, Hospital Clínic, IDIBAPS, Barcelona, Spain.
authors.forename: Armando
authors.initials: A
authors.lastname: Lopez-Guillermo
authors.affiliation: Unitat de Hematología, Hospital Clíınic, IDIBAPS, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Elias
authors.initials: E
authors.lastname: Campo
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Viktor
authors.initials: V
authors.lastname: Ljungström
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Larry
authors.initials: L
authors.lastname: Mansouri
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Richard
authors.initials: R
authors.lastname: Rosenquist
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden.
authors.forename: Tobias
authors.initials: T
authors.lastname: Sjöblom
authors.affiliation: Department of Immunology, Genetics and Pathology, Science for Life laboratory, Uppsala University, Uppsala, Sweden. mats.hellstrom@igp.uu.se.
authors.forename: Mats
authors.initials: M
authors.lastname: Hellström
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D004251:DNA Transposable Elements / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics*; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy* / Q000235:genetics*; D016296:Mutagenesis / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D048493:Proto-Oncogene Proteins B-raf / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014740:Vidarabine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D004251:DNA Transposable Elements; D014157:Transcription Factors; D017346:Protein Serine-Threonine Kinases; D048493:Proto-Oncogene Proteins B-raf; D014740:Vidarabine; C024352:fludarabine