RAS Pathway Mutations in Juvenile Myelomonocytic Leukemia

2008 ◽  
Vol 119 (4) ◽  
pp. 207-211 ◽  
Author(s):  
Peter D. Emanuel
Keyword(s):  
Juvenile Myelomonocytic Leukemia ◽  
Ras Pathway ◽  
Myelomonocytic Leukemia

scholarly journals Heterogeneous disease-propagating stem cells in juvenile myelomonocytic leukemia

2021 ◽  
Vol 218 (2) ◽  
Author(s):  
Eleni Louka ◽  
Benjamin Povinelli ◽  
Alba Rodriguez-Meira ◽  
Gemma Buck ◽  
Wei Xiong Wen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Stem Cell ◽  
Single Cell ◽  
Rna Sequencing ◽  
Childhood Leukemia ◽  
Clonal Evolution ◽  
Juvenile Myelomonocytic Leukemia ◽  
Hematopoietic Stem ◽  
Ras Pathway ◽  
Myelomonocytic Leukemia

Juvenile myelomonocytic leukemia (JMML) is a poor-prognosis childhood leukemia usually caused by RAS-pathway mutations. The cellular hierarchy in JMML is poorly characterized, including the identity of leukemia stem cells (LSCs). FACS and single-cell RNA sequencing reveal marked heterogeneity of JMML hematopoietic stem/progenitor cells (HSPCs), including an aberrant Lin−CD34+CD38−CD90+CD45RA+ population. Single-cell HSPC index-sorting and clonogenic assays show that (1) all somatic mutations can be backtracked to the phenotypic HSC compartment, with RAS-pathway mutations as a “first hit,” (2) mutations are acquired with both linear and branching patterns of clonal evolution, and (3) mutant HSPCs are present after allogeneic HSC transplant before molecular/clinical evidence of relapse. Stem cell assays reveal interpatient heterogeneity of JMML LSCs, which are present in, but not confined to, the phenotypic HSC compartment. RNA sequencing of JMML LSC reveals up-regulation of stem cell and fetal genes (HLF, MEIS1, CNN3, VNN2, and HMGA2) and candidate therapeutic targets/biomarkers (MTOR, SLC2A1, and CD96), paving the way for LSC-directed disease monitoring and therapy in this disease.

Somatic mutations activating Wiskott-Aldrich syndrome protein concomitant with RAS pathway mutations in juvenile myelomonocytic leukemia patients

2018 ◽  
Vol 39 (4) ◽  
pp. 579-587 ◽  
Author(s):  
Alessandro Coppe ◽  
Leonardo Nogara ◽  
Matteo Samuele Pizzuto ◽  
Alice Cani ◽  
Simone Cesaro ◽  
...  
Keyword(s):  
Somatic Mutations ◽  
Juvenile Myelomonocytic Leukemia ◽  
Ras Pathway ◽  
Wiskott Aldrich Syndrome ◽  
Syndrome Protein ◽  
Myelomonocytic Leukemia

Genome-Wide Single Nucleotide Polymorphism Analysis in Juvenile Myelomonocytic Leukemia Uncovers Long-Range Uniparental Disomy Surrounding the NF1 Locus in Cases Associated with Type 1 Neurofibromatosis but Not in Cases with Mutant RAS or PTPN11.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1453-1453
Author(s):  
Christian Flotho ◽  
Doris Steinemann ◽  
Gudrun Göhring ◽  
Charles Mullighan ◽  
Geoffrey Neale ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Mitotic Recombination ◽  
Chromosome 7 ◽  
Juvenile Myelomonocytic Leukemia ◽  
Single Nucleotide ◽  
Ras Pathway ◽  
Nf1 Gene ◽  
Myelomonocytic Leukemia ◽  
Pathway Deregulation

Abstract Juvenile myelomonocytic leukemia (JMML) is a malignant hematopoietic disorder of early childhood with myeloproliferative and myelodysplastic properties. The proliferative component is a result of RAS pathway deregulation caused by somatic mutation in the RAS or PTPN11 oncogenes (60% of cases) or by underlying neurofibromatosis type 1 (NF-1) with a germline NF1 gene defect (clinically 11% of cases). To search for potential collaborating genetic abnormalities, we used Affymetrix GeneChip Mapping 50K arrays to analyze over 116,000 single nucleotide polymorphisms (SNPs) across the genome using DNA from bone marrow or peripheral blood granulocytes from 16 children with JMML and normal karyotype (mutant RAS, n=4; mutant PTPN11, n=7; NF-1, n=5). Quantitative evaluation of hybridization intensities at each SNP locus failed to identify recurrent allelic gains or losses in the 16 cases. We were specifically interested in chromosome 7 because monosomy 7 or interstitial/terminal 7q deletions are found in about 30% of JMML cases and it is conceivable that submicroscopic 7q lesions occur in the other cases but remain undetected by standard techniques. However, at the resolution provided by the arrays used here, we saw no evidence for genomic copy number alterations on chromosome 7. Interestingly, evaluation of the SNP allelotypes identified large regions of copy-neutral loss of heterozygosity (LOH) on chromosome 17q, including the NF1 locus, in 4 of the 5 samples from patients with JMML and NF-1. The LOH region spanned a genomic range of approximately 55 Mbp in each case and included more than 1,400 contiguous SNPs. Allelic copy numbers were normal within the homozygous regions, indicating uniparental isodisomy (UPD). Compatible with isodisomy, 17q was normal in the corresponding conventional karyotypes. By contrast, the array data provided no evidence for 17q UPD in any of the 12 JMML cases without NF-1. In all four cases with 17q UPD, the recombination breakpoints appeared to be confined to a 400-kbp region on 17q11.1–17q11.2; however, lack of parental or nonleukemic DNA precluded definitive mapping of the breakpoints. Of note, the 17p chromosomal arm retained heterozygosity in all cases, indicating that the p53 tumor suppressor was not affected by the UPD event. We confirmed 17q disomy in the four NF-1 samples using matrix-based comparative genomic hybridization and are currently verifying homozygosity of multiple microsatellites spaced across chromosome 17. Furthermore, NF1 mutational analysis is under way to show that the individual lesion within this tumor suppressor gene is biallelic in leukemic cells from patients with JMML and NF-1. In summary, we assume that a mitotic recombination event in an early hematopoietic progenitor cell led to UPD involving the NF1 locus. Our observations provide strong confirmatory evidence that it is indeed the NF1 gene that is responsible for the increased incidence of JMML in NF-1 patients. In addition, our data support the emerging role of mitotic recombination as a second hit in leukemogenesis and corroborate the concept that RAS pathway deregulation is central to JMML pathogenesis.

Gene mutations in the Ras pathway and the prognostic implication in Korean patients with juvenile myelomonocytic leukemia

2011 ◽  
Vol 91 (4) ◽  
pp. 511-517 ◽  
Author(s):  
Hyung-Doo Park ◽  
Soo Hyun Lee ◽  
Ki Woong Sung ◽  
Hong Hoe Koo ◽  
Nak Gyun Jung ◽  
...  
Keyword(s):  
Gene Mutations ◽  
Juvenile Myelomonocytic Leukemia ◽  
Prognostic Implication ◽  
Ras Pathway ◽  
Korean Patients ◽  
Myelomonocytic Leukemia

scholarly journals Comprehensive Mutational Analysis of Juvenile Myelomonocytic Leukemia Using Whole-Genome Sequencing

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2974-2974
Author(s):  
Yusuke Okuno ◽  
Hideki Muramatsu ◽  
Norihiro Murakami ◽  
Nozomu Kawashima ◽  
Manabu Wakamatsu ◽  
...  
Keyword(s):  
Whole Genome Sequencing ◽  
Rna Sequencing ◽  
Genome Sequencing ◽  
Somatic Mutations ◽  
Conflicts Of Interest ◽  
Driver Mutations ◽  
Juvenile Myelomonocytic Leukemia ◽  
Whole Genome ◽  
Ras Pathway ◽  
Myelomonocytic Leukemia

Background Juvenile myelomonocytic leukemia (JMML) is a rare and exclusively pediatric myelodysplastic/myeloproliferative neoplasm. This disease is genetically characterized by an extremely small number of somatic mutations (an average of 0.8 mutations/exome/patient). It has been shown that causative somatic and/or germline mutations activating the RAS pathway are located in PTPN11, NF1, NRAS, KRAS, and CBL in 85% of patients with JMML. Furthermore, up to 20% of the patients have additional secondary mutations including SETBP1, and JAK3 mutations. In 2% of the patients, we identified, by RNA sequencing, activating kinase lesions affecting ALK or ROS1. Such findings suggest that other kinase fusions are present in JMML. There is an exceptional scarcity of somatic passenger mutations on the exome, suggesting that a small number of driver mutations drive JMML. However, to date, this hypothesis has not been investigated by whole-genome sequencing. Patients and Methods We performed a whole-genome sequencing (WGS) study in 48 patients with JMML. Bone marrow specimens and in vitro-cultured T cells were used as tumor and germline samples, respectively. Next-generation sequencing was performed using a HiSeq X platform (Illumina). Data analysis was performed by our in-house pipeline. Specifically, the pipeline detects single nucleotide variants (SNVs), copy number variants, somatic loss of heterozygosity (LOH), and chromosomal structural variations (SVs). The study was approved by the institutional review board of Nagoya University Graduate School of Medicine. Results In each patient we detected an average of 28 somatic mutations. These were primarily C-to-T transition in the CpG context, indicating that the mutations occurred by cell division. Besides RAS pathway and known secondary mutations, we observed no significant accumulation of somatic mutations in either coding or non-coding regions. Although we detected RAS pathway mutations in 90% of the patients, all mutations were on exome. However, we identified germline microdeletions affecting CBL and NF1, which had not been identified by exome sequencing. Additionally, we found two LOH events that affected NF1. Bi-allelic inactivation of NF1 is generally observed in patients with JMML; however, no pathogenic SNVs were identified in these two patients. We identified two chromosomal translocations that caused activating kinase lesions (i.e., RANBP2-ALK and TBL1XR1-ROS1). These had been pointed out in our previous RNA sequencing study. Another patient carried a complex SV that affected XPO1 (encoding exportin 1 or chromosome region maintenance 1 protein homolog). Although fusion genes involving XPO1 are reported to be present in lymphoid malignancies, the role of this SV in JMML remains unclear. Conclusions JMML is characterized by driver mutations that are largely present within the exome. However, WGS can still play a role in identifying both coding and non-coding mutations. LOH events without pathogenic SNVs suggest the presence of novel regulatory mechanisms of NF1. Conclusively, JMML is characterized by a paucity of somatic alterations and driver mutations. Hence, current research efforts should focus on RAS pathway mutations and known secondary mutations, many of which can be targeted. Disclosures No relevant conflicts of interest to declare.

BRAF Mutations in Juvenile Myelomonocytic Leukemia.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4602-4602
Author(s):  
Andrica C.H. de Vries ◽  
Ronald W. Stam ◽  
Christian Kratz ◽  
Martin Zenker ◽  
Oskar A. Haas ◽  
...  
Keyword(s):  
Mononuclear Cells ◽  
Clinical Signs ◽  
Juvenile Myelomonocytic Leukemia ◽  
Reaction Products ◽  
Braf Gene ◽  
Braf Mutations ◽  
Ras Pathway ◽  
Coding Sequence ◽  
Ras Genes ◽  
Myelomonocytic Leukemia

Abstract Approximately 75% of patients with juvenile myelomonocytic leukemia (JMML) harbour mutations in PTPN11, NF1 and RAS genes. The remaining cases presumably carry somatic mutations in other genes in the RAS pathway. BRAF plays a central role in this pathway between RAS and downstream molecules including MEK and ERK. BRAF mutations frequently occur in cancer. Recently, BRAF mutations were found in leukemia. Besides that, germline BRAF mutations cause cardio-facio-cutaneous syndrome, which shares many features with Noonan syndrome (NS). NS predisposes to a myeloproliferative disease resembling JMML. In 65 JMML patients screening for V600E mutations in exon 15 of the BRAF gene was performed from mononuclear cells. In a subset of patients, without RAS or PTPN11 mutations, and no clinical signs of NF1, the entire coding sequence of BRAF was analyzed. Sequence analysis was performed by direct, bidirectional sequencing of purified polymerase chain reaction products. In none of the 65 cases a V600E mutation of the BRAF gene was found. In a subset of patients in which the entire coding sequence of BRAF was analyzed, no mutations were identified either. Mutant proteins of the RAS-RAF-MEK-ERK pathway play an important role in the pathogenesis of JMML, resulting in GM-CSF hypersensitivity. In about 75% of the JMML cases these mutations affect RAS, NF1 or PTPN11 genes. The hypothesis for this study was that BRAF might play an important role in JMML as it is an important downstream effector of RAS. Our data show that apparently BRAF mutations do not play a role in JMML. Therefore, additional analysis of genes of the RAS pathway will be necessary to identify genetic aberrations in cases without known mutations.

scholarly journals Evidence-Based Minireview: Myelodysplastic syndrome/myeloproliferative neoplasm overlap syndromes: a focused review

Hematology ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 460-464
Author(s):  
Mrinal M. Patnaik ◽  
Terra Lasho
Keyword(s):  
Myelodysplastic Syndrome ◽  
Late Onset ◽  
Myeloproliferative Neoplasm ◽  
Treatment Modalities ◽  
Juvenile Myelomonocytic Leukemia ◽  
Ras Pathway ◽  
Overlap Syndromes ◽  
Recurrent Mutations ◽  
Male Preponderance ◽  
Myelomonocytic Leukemia

Abstract Myelodysplastic syndrome (MDS)/myeloproliferative neoplasm (MPN) overlap syndromes are unique myeloid neoplasms, with overlapping features of MDS and MPN. They consist of four adult onset entities including chronic myelomonocytic leukemia (CMML), MDS/MPN-ring sideroblasts-thrombocytosis (MDS/MPN-RS-T), BCR-ABL1 negative atypical chronic myeloid leukemia (aCML) and MDS/MPN-unclassifiable (MDS/MPN-U); with juvenile myelomonocytic leukemia (JMML) being the only pediatric onset entity. Among these overlap neoplasms, CMML is the most frequent and is hallmarked by the presence of sustained peripheral blood monocytosis with recurrent mutations involving TET2 (60%), SRSF2 (50%) and ASXL1 (40%); with RAS pathway mutations and JAK2V617F being relatively enriched in proliferative CMML subtypes (WBC ≥13 × 109/L). CMML usually presents in the 7th decade of life, with a male preponderance and is associated with a median overall survival of <36 months. Adverse prognosticators in CMML include increasing age, high WBC, presence of circulating immature myeloid cells, anemia, thrombocytopenia and truncating ASXL1 mutations. While allogeneic stem cell transplantation remains the only curative option, given the late onset of this neoplasm and high frequency of comorbidities, most patients remain ineligible. Hypomethylating agents such as azacitidine, decitabine and oral decitabine/cedazuridine have been US FDA approved for the management of CMML, with overall response rates of 40-50% and complete remission rates of <20%. While these agents epigenetically restore hematopoiesis in a subset of responding patients, they do not impact mutational allele burdens and eventual disease progression to AML remains inevitable. Newer treatment modalities exploiting epigenetic, signaling and splicing abnormalities commonly seen in CMML are much needed.

Juvenile myelomonocytic leukemia displays mutations in components of the RAS pathway and the PRC2 network

2015 ◽  
Vol 47 (11) ◽  
pp. 1334-1340 ◽  
Author(s):  
Aurélie Caye ◽  
Marion Strullu ◽  
Fabien Guidez ◽  
Bruno Cassinat ◽  
Steven Gazal ◽  
...  
Keyword(s):  
Juvenile Myelomonocytic Leukemia ◽  
Ras Pathway ◽  
Myelomonocytic Leukemia

scholarly journals Immunophenotypic and Genetic Overlap between JMML and CMML

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1803-1803
Author(s):  
Cody E. Cotner ◽  
Mitul Modi ◽  
Gerald Wertheim ◽  
Michele Paessler ◽  
Sarah K. Tasian ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Histone Modification ◽  
Research Funding ◽  
Juvenile Myelomonocytic Leukemia ◽  
Cell Transplant ◽  
Sequencing Analysis ◽  
Hematopoietic Stem ◽  
Bone Marrow Biopsies ◽  
Ras Pathway ◽  
Myelomonocytic Leukemia

Abstract Introduction: Juvenile myelomonocytic leukemia (JMML) is a rare hematological malignancy of early childhood with characteristics of both myeloproliferative neoplasms and myelodysplastic syndromes. JMML shares pathological features and diagnostic criteria with chronic myelomonocytic leukemia (CMML), a malignancy predominantly affecting the elderly. While 85% of patients with JMML have somatic or germline mutations in RAS pathway genes (NF1, NRAS, KRAS, PTPN11, and CBL), the most frequently mutated genes in CMML include TET2, SRSF2, ASXL1, and RAS and are generally somatic-only. The extent to which histone modification genes (ASXL1, EZH2) or spliceosome machinery genes (SF3B1, SRSF2, U2AF1, ZRSR2) play a role in JMML pathogenesis is unclear. Despite mutational differences, both JMML and CMML manifest as myelomonocytic proliferation with varying amounts of dysplasia in the bone marrow. Clusters of clonally-related CD123+ plasmacytoid dendritic cells (PDCs) have been observed in the bone marrow of patients with CMML but have not been investigated in JMML. Here, we report the mutation profiles and immunophenotypic characteristics of JMML specimens from children treated at our institution. Methods: The pathology archives (1987-2017) at the Children's Hospital of Philadelphia (CHOP) were searched to identify JMML cases (n=21) and included formalin fixed paraffin-embedded diagnostic bone marrow biopsies and splenectomy tissue obtained prior to hematopoietic stem cell transplant. JMML diagnosis was confirmed in all cases by clinicopathological review. Cytogenetic analysis and whole genome SNP array were performed at initial clinical presentation. Genomic DNA and RNA were extracted from JMML patients' bone marrow (n=8) and spleen tissue (n=10) for next-generation sequencing analysis of 118 cancer genes for sequence and copy number variants and 110 genes for known and novel fusions via our custom CHOP Hematologic Cancer Panel. CD123 immunohistochemical (IHC) staining was performed on bone marrow and spleen tissues from children with JMML. Presence of CD123+ PDC clusters was evaluated manually and by digital image analysis. CD123 staining was enumerated using the Aperio Image Scope quantitation of membranous staining v9 with the analysis parameters set such that normal endothelial staining was quantified as 1+, and true CD123 staining cells were quantified as 2+ or 3+. The percentage of CD123+ cells (out of total cellularity) was calculated. Bone marrow from patients with non-JMML myeloid malignancies (n=6) and splenectomy tissue from patients with sickle cell anemia (n=8) were used as controls for the CD123 IHC analysis. Results: We confirmed canonical JMML-associated somatic or germline NF1 (n=3), NRAS (n=4), KRAS (n=2), PTPN11 (n=6), or CBL (n=2) mutations in 16 of the 17 (94%) patients with sequencing data. Interestingly, both PTPN11A72T and NF1R2637* mutations were detected in one patient. In addition, we found potential variants in genes affecting histone modifications (ASXL1, DNMT3A, KDM6A, SETD2), spliceosomal processes (SF3B1, U2AF1), transcription (BCOR, RUNX1, ETV6), or cellular growth (SETBP1, BRAF) in 8/17 patients (47%). While mutations in these genes have been well-characterized in other myeloid disorders, many of these alterations have not been reported to date in children with JMML or are currently of unclear biologic and prognostic significance. We also observed increased clustering of CD123+ PDCs in bone marrow and spleens from patients with JMML compared to IHC staining of control tissues. 2.2 ± 0.42% and 1.8 ± 0.74% of cells expressed CD123 in the spleen and bone marrow specimens, respectively. Control bone marrow and spleen samples did not show significant CD123+ staining. Conclusions: Our study demonstrates frequent variants in histone modification, splicing, and transcription-associated genes in JMML specimens in addition to known pathogenic RAS pathway mutations. We further report histopathologic CD123+ PDC clustering in JMML specimens analogous to that observed in CMML, which may aid in the workup of this often difficult-to-diagnose disease. Our findings of genetic and immunophenotypic overlap between JMML and CMML suggest similarities in pathogenesis despite typical presentation at extremes of age. Disclosures Tasian: Aleta Biopharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Research Funding; Incyte Corporation: Research Funding.

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