TP53 mutations in myelodysplastic syndromes with deletion of 5q

The myelodysplastic syndromes (MDS) constitute a heterogeneous group of malignant bone marrow disorders characterized by peripheral cytopenia(s) and increased risk of progression to acute myeloid leukemia (AML). International Prognostic Scoring system (IPSS) Low- or Intermediate (INT)-1 risk MDS with a deletion of 5q (del5q) were considered to have an indolent course and a low risk for progression to AML as compared to other MDS subtypes. However, more recent studies have shown that overall survival (OS) and risk for AML progression vary greatly in del(5q) MDS patients indicating that factors beyond established risk scoring systems impact patient outcome. Molecular abnormalities have emerged as putative prognostic markers. We performed molecular studies in a patient with classical 5q-syndrome who unexpectedly evolved to high-risk MDS with complex karyotype (Paper I). Immunohistochemistry (IHC) of pre-treatment marrow biopsies revealed a small fraction of progenitors with strong p53 expression and sequencing confirmed a TP53 mutation. TP53 mutated subclones had not been described in MDS with isolated del(5q) and indicated a previously unknown heterogeneity. In a subsequent study of 55 patients with lower-risk del(5q) MDS, 18% of the patients were found to have TP53 mutated subclones at diagnosis which rendered them at higher risk for progression (Paper II). Interestingly, the association with outcome was even stronger for p53 IHC indicating a high sensitivity of this method for early identification of patients with adverse outcome. As a next step, we assessed p53 protein expression in a cohort of 85 lower-risk del(5q) MDS patients treated with lenalidomide within a clinical trial (Paper IV). P53 IHC positive patients showed significantly shorter overall survival, higher risk for leukemic transformation, and lower cytogenetic response rate to lenalidomide, hence validating the results from Paper II. Importantly, pyrosequencing analysis of microdissected IHC stained cells confirmed that cells with strong staining carried TP53 mutations, while moderate staining reflected wild-type TP53. Due to the apparently exquisite sensitivity of the del(5q) clone to len, we hypothesized that higher doses of lenalidomide may induce cytogenetic and clinical responses also in patients with high-risk MDS/AML with chromosome 5 abnormalities who were refractory or ineligible for standard treatment (Paper III). In this study, we demonstrated that treatment was able to inhibit the del(5q)tumor clone in a cohort of patients with extremely advanced disease, which suggests that the selective inhibitory effect of len in vitro may be translated into a therapeutic response in vivo. Importantly, TP53 mutations were common (62%) in this cohort, and uniformly associated with treatment failure. Altogether, our findings suggest an important role of the p53 pathway in both low- and high-risk del(5q) MDS, and in relation to treatment with lenalidomide. These findings will have major implications for risk stratification and the choice of therapy

MicroRNA expression in multiple myeloma is associated with genetic subtype, isotype and survival

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited - Copyright @ 2011 Chi et al.Background: MicroRNAs are small RNA species that regulate gene expression post-transcriptionally and are aberrantly expressed in many cancers including hematological malignancies. However, the role of microRNAs in the pathogenesis of multiple myeloma (MM) is only poorly understood. We therefore used microarray analysis to elucidate the complete miRNome (miRBase version 13.0) of purified tumor (CD138+) cells from 33 patients with MM, 5 patients with monoclonal gammopathy of undetermined significance (MGUS) and 9 controls. Results: Unsupervised cluster analysis revealed that MM and MGUS samples have a distinct microRNA expression profile from control CD138+ cells. The majority of microRNAs aberrantly expressed in MM (109/129) were up-regulated. A comparison of these microRNAs with those aberrantly expressed in other B-cell and T-cell malignancies revealed a surprising degree of similarity (~40%) suggesting the existence of a common lymphoma microRNA signature. We identified 39 microRNAs associated with the pre-malignant condition MGUS. Twenty-three (59%) of these were also aberrantly expressed in MM suggesting common microRNA expression events in MM progression. MM is characterized by multiple chromosomal abnormalities of varying prognostic significance. We identified specific microRNA signatures associated with the most common IgH translocations (t(4;14) and t(11;14)) and del(13q). Expression levels of these microRNAs were distinct between the genetic subtypes (by cluster analysis) and correctly predicted these abnormalities in > 85% of cases using the support vector machine algorithm. Additionally, we identified microRNAs associated with light chain only myeloma, as well as IgG and IgA-type MM. Finally, we identified 32 microRNAs associated with event-free survival (EFS) in MM, ten of which were significant by univariate (logrank) survival analysis. Conclusions: In summary, this work has identified aberrantly expressed microRNAs associated with the diagnosis, pathogenesis and prognosis of MM, data which will prove an invaluable resource for understanding the role of microRNAs in this devastating disease.This work was funded by grants from Leukaemia and Lymphoma Research (JC, EB, X-HC, DT, JB and JSW) and the Julian Starmer-Smith Memorial Fund (CHL). The authors acknowledge financial support from the Department of Health via the National Institute for Health Research (NIHR) comprehensive Biomedical Research Centre award to Oxford Radcliffe NHS Trust

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Molecular and clinical features of refractory anemia with ringed sideroblasts associated with marked thrombocytosis.

We studied patients with myeloid neoplasm associated with ringed sideroblasts and/or thrombocytosis. The combination of ringed sideroblasts 15% or greater and platelet count of 450 x 10(9)/L or greater was found in 19 subjects fulfilling the diagnostic criteria for refractory anemia with ringed sideroblasts (RARS) associated with marked thrombocytosis (RARS-T), and in 3 patients with primary myelofibrosis. JAK2 and MPL mutations were detected in circulating granulocytes and bone marrow CD34+ cells, but not in T lymphocytes, from 11 of 19 patients with RARS-T. Three patients with RARS, who initially had low to normal platelet counts, progressed to RARS-T, and 2 of them acquired JAK2 (V617F) at this time. In female patients with RARS-T, granulocytes carrying JAK2 (V617F) represented only a fraction of clonal granulocytes as determined by X-chromosome inactivation patterns. RARS and RARS-T patient groups both consistently showed up-regulation of ALAS2 and down-regulation of ABCB7 in CD34+ cells, but several other genes were differentially expressed, including PSIP1 (LEDGF), CXCR4, and CDC2L5. These observations suggest that RARS-T is indeed a myeloid neoplasm with both myelodysplastic and myeloproliferative features at the molecular and clinical levels and that it may develop from RARS through the acquisition of somatic mutations of JAK2, MPL, or other as-yet-unknown genes

Somatic SF3B1 mutation in myelodysplasia with ring sideroblasts

Chronic Myeloid Disorders Working Group of the International Cancer Genome Consortium.-- et al.The myelodysplastic syndromes are a heterogeneous group of hematologic cancers characterized by low blood counts, most commonly anemia, and a risk of progression to acute myeloid leukemia.1 These disorders have increased in prevalence and are expected to continue to do so. Blood films and bone marrow¿biopsy specimens from patients with myelodysplastic syndromes show dysplastic changes in myeloid cells, with abnormal proliferation and differentiation of one or more lineages. Target genes of recurrent chromosomal aberrations have been mapped,2,3 and several genes have been identified as recurrently mutated in these disorders, including NRAS (encoding neuroblastoma RAS viral oncogene homologue), TP53 (encoding tumor protein p53), RUNX1 (encoding runt-related transcription factor 1), CBL (encoding Cas-Br-M ecotropic retroviral transforming sequence),4,5 TET2 (encoding tet oncogene family member 2),6,7 ASXL1 (encoding additional sex combs¿like protein 1),8,9 and EZH2 (encoding enhancer of zeste homologue 2).10 With the exception of TET2, most of these genes are mutated in no more than 5 to 15% of cases, and generally the mutation rates are lower in the more benign subtypes of the disease. The myelodysplastic syndromes can be divided into several categories on the basis of bone marrow and peripheral-blood morphologic characteristics and cytogenetic changes.11 In low-risk disease, such as refractory anemia, cytopenias are the major clinical challenge, whereas high-risk disease, such as refractory anemia with excess blasts, is characterized by both cytopenias and a high rate of transformation to acute myeloid leukemia. More than a quarter of patients with myelodysplastic syndromes have large numbers of ring sideroblasts in the bone marrow,12 a sufficiently distinctive morphologic abnormality to warrant a separate designation. Ring sideroblasts are characteristically seen on iron staining of bone marrow aspirates as differentiating erythroid cells with a complete or partial ring of iron-laden mitochondria surrounding the nucleus. Several genetic lesions underpinning inherited sideroblastic anemias have been identified,13 including loss-of-function mutations in the genes ALAS2 (encoding delta aminolevulinate synthase 2), ABCB7 (encoding ATP-binding cassette, subfamily B, member 7), and SLC25A38 (solute carrier family 25, member 38). The pathogenesis of ring sideroblasts in myelodysplastic syndromes, however, remains obscure, although gene-expression studies have revealed up-regulation of genes involved in heme synthesis (including ALAS2) and down-regulation of ABCB7.14,15 We reasoned that the identification of recurrently mutated cancer genes in low-grade myelodysplastic syndromes could prove useful for the diagnosis of these disorders and provide new insights into the molecular pathogenesis of these syndromesSupported by grants from the Wellcome Trust (077012/Z/05/Z, for the overall study, as well as WT088340MA, to Dr. Campbell), the Kay Kendall Leukaemia Fund, Leukemia Lymphoma Research (for the overall study and to Drs. Boultwood, Green, Vyas, and Wainscoat), the Adenoid Cystic Carcinoma Research Foundation, the Medical Research Council (MRC) (to Dr. Warren), the Oxford National Institutes for Health Research Biomedical Research Centre (to Drs. Boultwood, Vyas, and Wainscoat), the Swedish Cancer Society (to Dr. Hellstrom-Lindburg), the International Human Frontier Science Program Organization (to Dr. Varela), the Department of Veterans Affairs and the National Institutes of Health (R01-124929, P01-155249, P50- 100007, and P01-78378, to Drs. Munshi and Anderson), the Association for International Cancer Research and the Leukemia Lymphoma Society (to Drs. Warren and Green), Associazione Italiana per la Ricerca sul Cancro (to the University of Pavia, the University of Milan Bicocca, and Dr. Cazzola), and Fondazione Cariplo (to the University of Pavia and the University of Milan Bicocca).Peer Reviewe

Gene silencing by DNA methylation in haematological malignancies.

The past decade has seen an explosion of interest in the epigenetics of cancer, with an increasing understanding that this form of genomic modification plays a critical role in pathogenesis. The malignant phenotype results from a step-wise increase of both genetic abnormalities and epigenetic modifications, leading to dysregulation of critical genes controlling cell growth, differentiation and apoptosis. The methylation of CpG islands within gene promoters is a major epigenetic transcriptional control mechanism that is frequently dysregulated in human cancer. This phenomenon (methylation of CpG islands) plays a critical role in the transcriptional silencing of tumour suppressor genes in cancer and has prompted the development and testing of several demethylating agents aimed at reversing this process. Clinical trials using epigenetically targeted therapies have yielded particularly promising results in the myelodysplastic syndromes (MDS), in which tumour suppressor gene silencing by promoter methylation is a frequent event. Several genes and gene pathways disrupted by aberrant CpG island methylation have now been identified in haematological malignancies, the most frequently studied being the cell cycle inhibitors p16 (now termed CDKN2A; mostly methylated in lymphoid malignancy) and p15 (now termed CDKN2B; commonly methylated in lymphoid and myeloid malignancies). This review will discuss the role that aberrant gene silencing by promoter hypermethylation plays in the molecular pathogenesis of haematological malignancies and assess the clinical potential of demethylating agents for the management of patients

Clonality in the myelodysplastic syndromes.

The myelodysplastic syndromes (MDSs) comprise a heterogeneous group of stem cell disorders involving cytopenia and dysplastic changes in 3 hematopoietic lineages. Although it is accepted that MDS is a clonal disorder, the exact nature of the involvement of multipotent stem cells and progenitor cells has not been resolved. Most clonality studies of MDS support the proposal that the primary neoplastic event occurs, in most patients, at the level of a committed myeloid progenitor cell, capable of differentiation into multiple myeloid lineages. The extent of the involvement of T and B lymphocytes in MDS remains controversial. Much of the variation reported may result from disease heterogeneity and technical issues such as skewed methylation patterns occurring in studies analyzing X-chromosome inactivation patterns (XCIP) and possible impurities in lymphocyte preparation. A great deal of the evidence in support of T-lymphocyte involvement in MDS has been generated by XCIP studies, and some of these data need to be treated with caution, especially data from studies in which appropriate controls were omitted. In contrast, B-lymphocyte involvement in some patients with MDS is based on studies using more robust technology including combined immunophenotyping and fluorescence in situ hybridization. Clonality studies involving myeloid and lymphoid cells in MDS have yielded discrepant results with regard to the potential involvement of multipotent (lympho-myeloid) hematopoietic stem cells (HSCs). However, failure to detect a clonal marker in all cells of all lineages does not preclude multipotent-HSC involvement. Some recent studies have produced compelling evidence to show that, in some patients with MDS, the multipotent HSC is the target of the primary neoplastic event. It now seems probable that MDS arises in multipotent HSCs more commonly than previously recognized. Such data not only provide important new insights into the biology of MDS but also may have therapeutic implications. The determination of whether multipotent HSCs are involved in the MDS clone may be important for the use of autologous stem cell transplantation in these patients