title: ATM mutations uniformly lead to ATM dysfunction in chronic lymphocytic leukemia: application of functional test using doxorubicin.
abstract: ATM abnormalities are frequent in chronic lymphocytic leukemia and represent an important prognostic factor. Sole 11q deletion does not result in ATM inactivation by contrast to biallelic defects involving mutations. Therefore, the analysis of ATM mutations and their functional impact is crucial. In this study, we analyzed ATM mutations in predominantly high-risk patients using: i) resequencing microarray and direct sequencing; ii) Western blot for total ATM level; iii) functional test based on p21 gene induction after parallel treatment of leukemic cells with fludarabine and doxorubicin. ATM dysfunction leads to impaired p21 induction after doxorubicin exposure. We detected ATM mutation in 16% (22 of 140) of patients, and all mutated samples manifested demonstrable ATM defect (impaired p21 upregulation after doxorubicin and/or null protein level). Loss of ATM function in mutated samples was also evidenced through defective p53 pathway activation after ionizing radiation exposure. ATM mutation frequency was 34% in patients with 11q deletion, 4% in the TP53-defected group, and 8% in wild-type patients. Our functional test, convenient for routine use, showed high sensitivity (80%) and specificity (97%) for ATM mutations prediction. Only cells with ATM mutation, but not those with sole 11q deletion, were resistant to doxorubicin. As far as fludarabine is concerned, this difference was not observed. Interestingly, patients from both these groups experienced nearly identical time to first treatment. In conclusion, ATM mutations either alone or in combination with 11q deletion uniformly led to demonstrable ATM dysfunction in patients with chronic lymphocytic leukemia and mutation presence can be predicted by the functional test using doxorubicin.
authors.affiliation: Department of Molecular Medicine, CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
authors.forename: Veronika
authors.initials: V
authors.lastname: Navrkalova
authors.forename: Ludmila
authors.initials: L
authors.lastname: Sebejova
authors.forename: Jana
authors.initials: J
authors.lastname: Zemanova
authors.forename: Jana
authors.initials: J
authors.lastname: Kminkova
authors.forename: Blanka
authors.initials: B
authors.lastname: Kubesova
authors.forename: Jitka
authors.initials: J
authors.lastname: Malcikova
authors.forename: Marek
authors.initials: M
authors.lastname: Mraz
authors.forename: Jana
authors.initials: J
authors.lastname: Smardova
authors.forename: Sarka
authors.initials: S
authors.lastname: Pavlova
authors.forename: Michael
authors.initials: M
authors.lastname: Doubek
authors.forename: Yvona
authors.initials: Y
authors.lastname: Brychtova
authors.forename: David
authors.initials: D
authors.lastname: Potesil
authors.forename: Veronika
authors.initials: V
authors.lastname: Nemethova
authors.forename: Jiri
authors.initials: J
authors.lastname: Mayer
authors.forename: Sarka
authors.initials: S
authors.lastname: Pospisilova
authors.forename: Martin
authors.initials: M
authors.lastname: Trbusek
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D064007:Ataxia Telangiectasia Mutated Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects* / Q000502:physiology; D002872:Chromosome Deletion; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics; D015331:Cohort Studies; D004317:Doxorubicin / Q000494:pharmacology*; D005260:Female; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000175:diagnosis / Q000235:genetics* / Q000473:pathology*; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D012189:Retrospective Studies
chemical_list: D004317:Doxorubicin; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins