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The Hague, Netherlands

De Rooij J.D.E.,Erasmus MC Sophia Childrens Hospital | Hollink I.H.I.M.,Erasmus MC Sophia Childrens Hospital | Arentsen-Peters S.T.C.J.M.,Erasmus MC Sophia Childrens Hospital | Van Galen J.F.,Erasmus Medical Center | And 10 more authors.

Cytogenetic abnormalities and early response to treatment are the main prognostic factors in acute myeloid leukemia (AML). Recently, NUP98/NSD1 (t(5; 11)(q35; p15)), a cytogenetically cryptic fusion, was described as recurrent event in AML, characterized by dismal prognosis and HOXA/B gene overexpression. Using split-signal fluorescence in situ hybridization, other NUP98-rearranged pediatric AML cases were identified, including several acute megakaryoblastic leukemia (AMKL) cases with a cytogenetically cryptic fusion of NUP98 to JARID1A (t(11;15)(p15;q35)). In this study we screened 105 pediatric AMKL cases to analyze the frequency of NUP98/JARID1A and other recurrent genetic abnormalities. NUP98/JARID1A was identified in 11/105 patients (10.5%). Other abnormalities consisted of RBM15/MKL1 (n=16), CBFA2T3/GLIS2 (n=13) and MLL-rearrangements (n=13). Comparing NUP98/JARID1A-positive patients with other pediatric AMKL patients, no significant differences in sex, age and white blood cell count were found. NUP98/JARID1A was not an independent prognostic factor for 5-year overall (probability of overall survival (pOS)) or event-free survival (probability of event-free survival (pEFS)), although the 5-year pOS for the entire AMKL cohort was poor (42±6%). Cases with RBM15/MLK1 fared significantly better in terms of pOS and pEFS, although this was not independent from other risk factors in multivariate analysis. NUP98/JARID1A cases were characterized by HOXA/B gene overexpression, which is a potential druggable pathway. In conclusion, NUP98/JARID1A is a novel recurrent genetic abnormality in pediatric AMKL. © 2013 Macmillan Publishers Limited. Source

Emmrich S.,Hannover Medical School | Katsman-Kuipers J.E.,Pediatric Oncology Hematology Biochemistry | Henke K.,Hannover Medical School | Khatib M.E.,Hannover Medical School | And 15 more authors.

MicroRNAs (miRNAs) play a pivotal role in the regulation of hematopoiesis and development of leukemia. Great interest emerged in modulating miRNA expression for therapeutic purposes. In order to identify miRNAs, which specifically suppress leukemic growth of acute myeloid leukemia (AML) with t(8;21), inv(16) or mixed lineage leukemia (MLL) rearrangement by inducing differentiation, we conducted a miRNA expression profiling in a cohort of 90 cytogenetically characterized, de novo pediatric AML cases. Four miRNAs, specifically downregulated in MLL-rearranged, t(8;21) or inv(16) AMLs, were characterized by their tumor-suppressive properties in cell lines representing those respective cytogenetic groups. Among those, forced expression of miR-9 reduced leukemic growth and induced monocytic differentiation of t(8;21) AML cell lines in vitro and in vivo. The tumor-suppressive functions of miR-9 were specifically restricted to AML cell lines and primary leukemic blasts with t(8;21). On the other hand, these functions were not evident in AML blasts from patients with MLL rearrangements. We showed that miR-9 exerts its effects through the cooperation with let-7 to repress the oncogenic LIN28B/HMGA2 axis. Thus, miR-9 is a tumor suppressor-miR which acts in a stringent cell context-dependent manner. © 2014 Macmillan Publishers Limited. All rights reserved. Source

Homminga I.,Erasmus MC Sophia Childrens Hospital | Pieters R.,Erasmus MC Sophia Childrens Hospital | Langerak A.,Erasmus University Rotterdam | de Rooi J.,Erasmus University Rotterdam | And 24 more authors.
Cancer Cell

To identify oncogenic pathways in T cell acute lymphoblastic leukemia (T-ALL), we combined expression profiling of 117 pediatric patient samples and detailed molecular-cytogenetic analyses including the Chromosome Conformation Capture on Chip (4C) method. Two T-ALL subtypes were identified that lacked rearrangements of known oncogenes. One subtype associated with cortical arrest, expression of cell cycle genes, and ectopic NKX2-1 or NKX2-2 expression for which rearrangements were identified. The second subtype associated with immature T cell development and high expression of the MEF2C transcription factor as consequence of rearrangements of MEF2C, transcription factors that target MEF2C, or MEF2C-associated cofactors. We propose NKX2-1, NKX2-2, and MEF2C as T-ALL oncogenes that are activated by various rearrangements. © 2011 Elsevier Inc. Source

Hollink I.H.I.M.,Pediatric Oncology Hematology | van den Heuvel-Eibrink M.M.,Pediatric Oncology Hematology | Arentsen-Peters S.T.C.J.M.,Pediatric Oncology Hematology | Zimmermann M.,Hannover Medical School | And 13 more authors.

Background Dysfunctioning of CCAAT/enhancer binding protein α (C/EBP α) in acute myeloid leukemia can be caused, amongst others, by mutations in the encoding gene (CEBPA) and by promoter hypermethylation. CEBPA-mutated acute myeloid leukemia is associated with a favorable outcome, but this may be restricted to the case of double mutations in CEBPA in adult acute myeloid leukemia. In pediatric acute myeloid leukemia, data on the impact of these mutations are limited to one series, and data on promoter hypermethylation are lacking. Our objective was to investigate the characteristics, gene expression profiles and prognostic impact of the different CEBPA aberrations in pediatric acute myeloid leukemia. Design and Methods We screened a large pediatric cohort (n=252) for CEBPA single and double mutations by direct sequencing, and for promoter hypermethylation by methylation-specific polymerase chain reaction. Furthermore, we determined the gene-expression profiles (Affymetrix HGU133 plus 2.0 arrays) of this cohort (n=237). Results Thirty-four mutations were identified in 20 out of the 252 cases (7.9%), including 14 doublemutant and 6 single-mutant cases. CEBPA double mutations conferred a significantly better 5-year overall survival compared with single mutations (79% versus 25%, respectively; P=0.04), and compared with CEBPA wild-type acute myeloid leukemia excluding core-binding factor cases (47%; P=0.07). Multivariate analysis confirmed that the double mutations were an independent favorable prognostic factor for survival (hazard ratio 0.23, P=0.04). The combination of screening for promoter hypermethylation and gene expression profiling identified five patients with silenced CEBPA, of whom four cases relapsed. All cases characteristically expressed T-lymphoid markers. Moreover, unsupervised clustering of gene expression profiles showed a clustering of CEBPA double-mutant and silenced cases, pointing towards a common hallmark of abrogated C/EBPα-functioning in these acute myeloid leukemias. Conclusions We showed the independent favorable outcome of patients with CEBPA double-mutant acute myeloid leukemia in a large pediatric series. This molecular marker may, therefore, improve risk-group stratification in pediatric acute myeloid leukemia. For the first time, CEBPA-silenced cases are suggested to confer a poor outcome in pediatric acute myeloid leukemia, indicating that further investigation of this aberration is needed. Furthermore, clustering of gene expression profiles provided insight into the biological similarities and diversities of the different aberrations in CEBPA in pediatric acute myeloid leukemia. © 2011 Ferrata Storti Foundation. Source

Bachas C.,VU University Amsterdam | Schuurhuis G.J.,VU University Amsterdam | Hollink I.H.I.M.,Erasmus MC Sophia Childrens Hospital | Kwidama Z.J.,VU University Amsterdam | And 11 more authors.

Although virtually all pediatric patients with acute myeloid leukemia (AML) achieve a complete remission after initial induction therapy, 30%-40% of patients will encounter a relapse and have a dismal prognosis. To prevent relapses, personalized treatment strategies are currently being developed, which target specific molecular aberrations. To determine relevance of established AML type I/II mutations that may serve as therapeutic targets, we assessed frequencies of these mutations and their persistence during disease progression in a large group (n = 69) of paired diagnosis and relapse pediatric AML specimens. In 26 of 42 patients (61%) harboring mutations at either stage of the disease, mutation status changed between diagnosis and relapse, particularly in FLT3, WT1, and RAS genes. Presence or gain of type I/II mutations at relapse was associated with a shorter time to relapse (TTR), whereas absence or loss correlated with longer TTR. Moreover, an adverse outcome was found for patients with activating mutations at relapse, which was statistically significant for FLT3/ITD and WT1 mutations. These findings suggest that mutational shifts affect disease progression. We hence propose that risk stratification, malignant cell detection, and selection of personalized treatment should be based on status of type I/II mutations both at initial diagnosis and during follow-up. © 2010 by The American Society of Hematology. Source

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