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Valeria Visconte,
Heesun J Rogers,
Jarnail Singh,
John Barnard,
Manoj Bupathi, Fabiola Traina,
James McMahon,
Hideki Makishima,
Hadrian Szpurka,
Anna Jankowska, [......],
Anjali S Advani,
Edward Copelan,
Haruhiko Koseki,
Kyoichi Isono,
Richard A Padgett,
Sami Osman,
Kazunori Koide,
Christine O'Keefe,
Jaroslaw P Maciejewski,
Ramon V Tiu
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ABSTRACT: Whole exome/genome sequencing has been fundamental in the identification of somatic mutations in the spliceosome machinery in myelodysplastic syndromes (MDSs) and other hematologic disorders. SF3B1, splicing factor 3b subunit 1 is mutated in 60%-80% of refractory anemia with ring sideroblasts (RARS) and RARS associated with thrombocytosis (RARS-T), 2 distinct subtypes of MDS and MDS/myeloproliferative neoplasms (MDSs/MPNs). An idiosyncratic feature of RARS/RARS-T is the presence of abnormal sideroblasts characterized by iron overload in the mitochondria, called RS. Based on the high frequency of mutations of SF3B1 in RARS/RARS-T, we investigated the consequences of SF3B1 alterations. Ultrastructurally, SF3B1 mutants showed altered iron distribution characterized by coarse iron deposits compared with wild-type RARS patients by transmission electron microscopy. SF3B1 knockdown experiments in K562 cells resulted in down-regulation of U2-type intron-splicing by RT-PCR. RNA-sequencing analysis of SF3B1 mutants showed differentially used genes relevant in MDS pathogenesis, such as ASXL1, CBL, EZH, and RUNX families. A SF3B pharmacologic inhibitor, meayamycin, induced the formation of RS in healthy BM cells. Further, BM aspirates of Sf3b1 heterozygous knockout mice showed RS by Prussian blue. In conclusion, we report the first experimental evidence of the association between SF3B1 and RS phenotype. Our data suggest that SF3B1 haploinsufficiency leads to RS formation.
Blood 07/2012; 120(16):3173-86. · 9.90 Impact Factor
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Sarah Abu Kar,
Anna M Jankowska,
Hideki Makishima,
Valeria Visconte,
Andres Jerez,
Yuka Sugimoto,
Hideki Muramatsu, Fabiola Traina,
Manuel Afable,
Kathryn Guinta,
Ramon V Tiu,
Bartlomiej Przychodzen,
Hirotoshi Sakaguchi,
Seiji Kojima,
Mikkael A Sekeres,
Alan F List,
Michael A McDevitt,
Jaroslaw P Maciejewski
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ABSTRACT: Background
Chronic myelomonocytic leukemia is a heterogeneous disease with multifactorial molecular pathogenesis. Various recurrent somatic mutations can be detected alone or in combination in chronic myelomonocytic leukemia. Recently, recurrent mutations in spliceosomal genes have been discovered. We investigated the contribution of U2AF1, SRSF2 and SF3B1 mutations in the pathogenesis of chronic myelomonocytic leukemia and the closely related diseases.Methods
We genotyped a cohort of patients with chronic myelomoncytic leukemia, secondary acute myeloid leukemia derived from chronic myelomonocytic leukemia and juvenile myelomonocytic leukemia for somatic mutations in U2AF1, SRSF2, SF3B1 and of the other 12 most frequently affected genes in these conditions. Chromosomal abnormalities were assessed by nucleotide polymorphism array-based karyotyping. The presence of molecular lesions was correlated with clinical endpoints.ResultsMutations in SRSF2, U2AF1 and SF3B1 were found in 32%, 13% and 6% of cases, respectively. Spliceosomal genes were affected in various combinations with other mutations, including TET2, ASXL1, CBL, EZH2, RAS, IDH1/2, DNMT3A, TP53, UTX and RUNX1. Worse overall survival was associated with mutations in U2AF1 (p=.047) and DNMT3A (p=.015). RAS mutations had impact on overall surviva; in sAML (p=.0456). By comparison, our screen for juvenile myelomonocytic leukemia cases showed mutations in ASXL1 (4%), CBL (10%), and RAS (6%) but not in IDH1/2, TET2, EZH2, DNMT3A or 3 spliceosomal genes.ConclusionsSRSF2 and U2AF1 along with TET2 (48%) and ASXL1 (38%) are frequently affected by somatic mutations in chronic myelomonocytic leukemia, quite distinct from a profile seen in juvenile myelomonocytic leukemia. Our data also suggests that spliceosomal mutations are of ancestral origin.
Haematologica 07/2012; · 6.42 Impact Factor
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Fabiola Traina,
Valeria Visconte,
Anna M Jankowska,
Hideki Makishima,
Christine L O'Keefe,
Paul Elson,
Yingchun Han,
Fred H Hsieh,
Mikkael A Sekeres,
Raghuveer Singh Mali,
Matt Kalaycio,
Alan E Lichtin,
Anjali S Advani,
Hien K Duong,
Edward Copelan,
Reuben Kapur,
Sara T Olalla Saad,
Jaroslaw P Maciejewski,
Ramon V Tiu
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ABSTRACT: We hypothesized that analysis of single nucleotide polymorphism arrays (SNP-A) and new molecular defects may provide new insight in the pathogenesis of systemic mastocytosis (SM). SNP-A karyotyping was applied to identify recurrent areas of loss of heterozygosity and bidirectional sequencing was performed to evaluate the mutational status of TET2, DNMT3A, ASXL1, EZH2, IDH1/IDH2 and the CBL gene family. Overall survival (OS) was analyzed using the Kaplan-Meier method. We studied a total of 26 patients with SM. In 67% of SM patients, SNP-A karyotyping showed new chromosomal abnormalities including uniparental disomy of 4q and 2p spanning TET2/KIT and DNMT3A. Mutations in TET2, DNMT3A, ASXL1 and CBL were found in 23%, 12%, 12%, and 4% of SM patients, respectively. No mutations were observed in EZH2 and IDH1/IDH2. Significant differences in OS were observed for SM mutated patients grouped based on the presence of combined TET2/DNMT3A/ASXL1 mutations independent of KIT (P = 0.04) and sole TET2 mutations (P<0.001). In conclusion, TET2, DNMT3A and ASXL1 mutations are also present in mastocytosis and these mutations may affect prognosis, as demonstrated by worse OS in mutated patients.
PLoS ONE 01/2012; 7(8):e43090. · 4.09 Impact Factor
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Raghuveer Singh Mali,
Baskar Ramdas,
Peilin Ma,
Jianjian Shi,
Veerendra Munugalavadla,
Emily Sims,
Lei Wei,
Sasidhar Vemula,
Sarah C Nabinger,
Charles B Goodwin,
Rebecca J Chan, Fabiola Traina,
Valeria Visconte,
Ramon V Tiu,
Timothy A Lewis,
Andrew M Stern,
Qiang Wen,
John D Crispino,
H Scott Boswell,
Reuben Kapur
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ABSTRACT: We show constitutive activation of Rho kinase (ROCK) in cells bearing oncogenic forms of KIT, FLT3, and BCR-ABL, which is dependent on PI3K and Rho GTPase. Genetic or pharmacologic inhibition of ROCK in oncogene-bearing cells impaired their growth as well as the growth of acute myeloid leukemia patient-derived blasts and prolonged the life span of mice bearing myeloproliferative disease. Downstream from ROCK, rapid dephosphorylation or loss of expression of myosin light chain resulted in enhanced apoptosis, reduced growth, and loss of actin polymerization in oncogene-bearing cells leading to significantly prolonged life span of leukemic mice. In summary we describe a pathway involving PI3K/Rho/ROCK/MLC that may contribute to myeloproliferative disease and/or acute myeloid leukemia in humans.
Cancer cell 09/2011; 20(3):357-69. · 25.29 Impact Factor
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Anna M Jankowska,
Hideki Makishima,
Ramon V Tiu,
Hadrian Szpurka,
Yun Huang, Fabiola Traina,
Valeria Visconte,
Yuka Sugimoto,
Courtney Prince,
Christine O'Keefe,
Eric D Hsi,
Alan List,
Mikkael A Sekeres,
Anjana Rao,
Michael A McDevitt,
Jaroslaw P Maciejewski
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ABSTRACT: Chronic myelomonocytic leukemia (CMML), a myelodysplastic/myeloproliferative neoplasm, is characterized by monocytic proliferation, dysplasia, and progression to acute myeloid leukemia. CMML has been associated with somatic mutations in diverse recently identified genes. We analyzed 72 well-characterized patients with CMML (N = 52) and CMML-derived acute myeloid leukemia (N = 20) for recurrent chromosomal abnormalities with the use of routine cytogenetics and single nucleotide polymorphism arrays along with comprehensive mutational screening. Cytogenetic aberrations were present in 46% of cases, whereas single nucleotide polymorphism array increased the diagnostic yield to 60%. At least 1 mutation was found in 86% of all cases; novel UTX, DNMT3A, and EZH2 mutations were found in 8%, 10%, and 5.5% of patients, respectively. TET2 mutations were present in 49%, ASXL1 in 43%, CBL in 14%, IDH1/2 in 4%, KRAS in 7%, NRAS in 4%, and JAK2 V617F in 1% of patients. Various mutant genotype combinations were observed, indicating molecular heterogeneity in CMML. Our results suggest that molecular defects affecting distinct pathways can lead to similar clinical phenotypes.
Blood 08/2011; 118(14):3932-41. · 9.90 Impact Factor
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ABSTRACT: INTRODUCTION: Treatment options in myelodysplastic syndromes (MDS) remain limited. The introduction of novel therapies that can improve response rates and survival outcomes in MDS remains a challenge. Clofarabine is a purine nucleoside analog that works primarily via inhibition of DNA biosynthesis and the ribonucleotide reductase enzyme with recent evidence suggesting that at low doses it may affect DNA methylation. It has been successfully used in the treatment of acute myeloid leukemia (AML) and is under investigation in MDS. AREAS COVERED: A PubMed search for articles pertaining to clofarabine was conducted and streamlined to only include data on MDS or AML that evolved from MDS. Also included were clofarabine-related response and safety data from presentations at the 52(nd) Annual American Society of Hematology Meeting in Orlando, Florida, USA. EXPERT OPINION: Clinical trials using clofarabine in MDS and MDS/myeloproliferative neoplasms have produced overall response rates of 31 - 43% including complete responders. Although myelosuppression is an important side effect, clofarabine is generally well tolerated in MDS. Clofarabine is currently available in an intravenous form with an oral formulation presently under investigation, either as a single agent or in combination therapy in MDS. Larger studies may help clarify the viability of clofarabine in the treatment of MDS patients.
Expert Opinion on Investigational Drugs 07/2011; 20(7):1005-14. · 5.27 Impact Factor
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ABSTRACT: Myelodysplastic syndromes (MDS) are clonal hematologic neoplasms that can result in cytopenias and increase the risk of leukemic transformation. The disease is characterized by several recurrent cytogenetic defects, which can affect diagnosis, prognosis, and treatment. Metaphase cytogenetics (MC) is the gold standard in karyotypic analysis in hematology. Progress in molecular analysis, including additional karyotypic tools exemplified by fluorescence in situ hybridization, comparative genomic hybridization, and more importantly, single nucleotide polymorphism array (SNP-A) analysis, has led to increased detection of chromosomal abnormalities in myeloid malignancies and improved prognostic risk stratification. SNP-A, together with MC, has also been instrumental in the discovery of genes that have improved our understanding of the biology of MDS. Newly elucidated molecular abnormalities in MDS include mutations in CBL, TET2, ASXL1, IDH1/IDH2, EZH2, DNMT3A, and UTX. This review provides an update on the changing landscape of molecular and cytogenetic characterization in MDS and its significance in disease biology and clinical practice.
Current Hematologic Malignancy Reports 02/2011; 6(2):126-35.
