LMO2

Gene Summary

Gene:LMO2; LIM domain only 2 (rhombotin-like 1)
Aliases: TTG2, RBTN2, RHOM2, RBTNL1
Location:11p13
Summary:LMO2 encodes a cysteine-rich, two LIM-domain protein that is required for yolk sac erythropoiesis. The LMO2 protein has a central and crucial role in hematopoietic development and is highly conserved. The LMO2 transcription start site is located approximately 25 kb downstream from the 11p13 T-cell translocation cluster (11p13 ttc), where a number T-cell acute lymphoblastic leukemia-specific translocations occur. Alternative splicing results in multiple transcript variants encoding different isoforms.[provided by RefSeq, Nov 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:rhombotin-2
HPRD
Source:NCBIAccessed: 18 March, 2015

Ontology:

What does this gene/protein do?
Show (18)

Cancer Overview

Research Indicators

Publications Per Year (1990-2015)
Graph generated 18 March 2015 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

  • Oncogene Proteins
  • Childhood Cancer
  • Oncogenes
  • DNA-Binding Proteins
  • LIM Domain Proteins
  • Insertional Mutagenesis
  • Diffuse Large B-Cell Lymphoma
  • Transcription
  • Adolescents
  • Retroviridae
  • Oligonucleotide Array Sequence Analysis
  • United States Food and Drug Administration
  • Young Adult
  • Signal Transducing Adaptor Proteins
  • Thymus Neoplasms
  • Molecular Sequence Data
  • Mice, Transgenic
  • Adult T-Cell Leukemia-Lymphoma
  • Homeodomain Proteins
  • Basic Helix-Loop-Helix Transcription Factors
  • Gene Expression Profiling
  • Proto-Oncogene Proteins
  • Cell Differentiation
  • Metalloproteins
  • SCID
  • Genetic Therapy
  • Chromosome 11
  • X-Linked Combined Immunodeficiency Diseases
  • RTPCR
  • Precursor T-Cell Lymphoblastic Leukemia-Lymphoma
  • Tetraspanins
  • LMO2
  • Leukemic Gene Expression Regulation
  • Up-Regulation
  • Neoplasm Proteins
  • Cancer Gene Expression Regulation
  • T-Cell Leukemia
  • Leukaemia
  • Tumor Suppressor Proteins
  • Acute Lymphocytic Leukaemia
  • Base Sequence
  • Tumor Microenvironment
Tag cloud generated 18 March, 2015 using data from PubMed, MeSH and CancerIndex

Specific Cancers (1)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: LMO2 (cancer-related)

Goodings C, Tripathi R, Cleveland SM, et al.
Enforced expression of E47 has differential effects on Lmo2-induced T-cell leukemias.
Leuk Res. 2015; 39(1):100-9 [PubMed] Article available free on PMC after 01/01/2016 Related Publications
LIM domain only-2 (LMO2) overexpression in T cells induces leukemia but the molecular mechanism remains to be elucidated. In hematopoietic stem and progenitor cells, Lmo2 is part of a protein complex comprised of class II basic helix loop helix proteins, Tal1and Lyl1. The latter transcription factors heterodimerize with E2A proteins like E47 and Heb to bind E boxes. LMO2 and TAL1 or LYL1 cooperate to induce T-ALL in mouse models, and are concordantly expressed in human T-ALL. Furthermore, LMO2 cooperates with the loss of E2A suggesting that LMO2 functions by creating a deficiency of E2A. In this study, we tested this hypothesis in Lmo2-induced T-ALL cell lines. We transduced these lines with an E47/estrogen receptor fusion construct that could be forced to homodimerize with 4-hydroxytamoxifen. We discovered that forced homodimerization induced growth arrest in 2 of the 4 lines tested. The lines sensitive to E47 homodimerization accumulated in G1 and had reduced S phase entry. We analyzed the transcriptome of a resistant and a sensitive line to discern the E47 targets responsible for the cellular effects. Our results suggest that E47 has diverse effects in T-ALL but that functional deficiency of E47 is not a universal feature of Lmo2-induced T-ALL.

Mendes RD, Sarmento LM, Canté-Barrett K, et al.
PTEN microdeletions in T-cell acute lymphoblastic leukemia are caused by illegitimate RAG-mediated recombination events.
Blood. 2014; 124(4):567-78 [PubMed] Related Publications
Phosphatase and tensin homolog (PTEN)-inactivating mutations and/or deletions are an independent risk factor for relapse of T-cell acute lymphoblastic leukemia (T-ALL) patients treated on Dutch Childhood Oncology Group or German Cooperative Study Group for Childhood Acute Lymphoblastic Leukemia protocols. Some monoallelic mutated or PTEN wild-type patients lack PTEN protein, implying that additional PTEN inactivation mechanisms exist. We show that PTEN is inactivated by small deletions affecting a few exons in 8% of pediatric T-ALL patients. These microdeletions were clonal in 3% and subclonal in 5% of patients. Conserved deletion breakpoints are flanked by cryptic recombination signal sequences (cRSSs) and frequently have non-template-derived nucleotides inserted in between breakpoints, pointing to an illegitimate RAG recombination-driven activity. Identified cRSSs drive RAG-dependent recombination in a reporter system as efficiently as bona fide RSSs that flank gene segments of the T-cell receptor locus. Remarkably, equivalent microdeletions were detected in thymocytes of healthy individuals. Microdeletions strongly associate with the TALLMO subtype characterized by TAL1 or LMO2 rearrangements. Primary and secondary xenotransplantation of TAL1-rearranged leukemia allowed development of leukemic subclones with newly acquired PTEN microdeletions. Ongoing RAG activity may therefore actively contribute to the acquisition of preleukemic hits, clonal diversification, and disease progression.

Hwang HS, Park CS, Yoon DH, et al.
High concordance of gene expression profiling-correlated immunohistochemistry algorithms in diffuse large B-cell lymphoma, not otherwise specified.
Am J Surg Pathol. 2014; 38(8):1046-57 [PubMed] Related Publications
Diffuse large B-cell lymphoma (DLBCL) is classified into prognostically distinct germinal center B-cell (GCB) and activated B-cell subtypes by gene expression profiling (GEP). Recent reports suggest the role of GEP subtypes in targeted therapy. Immunohistochemistry (IHC) algorithms have been proposed as surrogates of GEP, but their utility remains controversial. Using microarray, we examined the concordance of 4 GEP-correlated and 2 non-GEP-correlated IHC algorithms in 381 DLBCLs, not otherwise specified. Subtypes and variants of DLBCL were excluded to minimize the possible confounding effect on prognosis and phenotype. Survival was analyzed in 138 cyclophosphamide, adriamycin, vincristine, and prednisone (CHOP)-treated and 147 rituximab plus CHOP (R-CHOP)-treated patients. Of the GEP-correlated algorithms, high concordance was observed among Hans, Choi, and Visco-Young algorithms (total concordance, 87.1%; κ score: 0.726 to 0.889), whereas Tally algorithm exhibited slightly lower concordance (total concordance 77.4%; κ score: 0.502 to 0.643). Two non-GEP-correlated algorithms (Muris and Nyman) exhibited poor concordance. Compared with the Western data, incidence of the non-GCB subtype was higher in all algorithms. Univariate analysis showed prognostic significance for Hans, Choi, and Visco-Young algorithms and BCL6, GCET1, LMO2, and BCL2 in CHOP-treated patients. On multivariate analysis, Hans algorithm retained its prognostic significance. By contrast, neither the algorithms nor individual antigens predicted survival in R-CHOP treatment. The high concordance among GEP-correlated algorithms suggests their usefulness as reliable discriminators of molecular subtype in DLBCL, not otherwise specified. Our study also indicates that prognostic significance of IHC algorithms may be limited in R-CHOP-treated Asian patients because of the predominance of the non-GCB type.

Treanor LM, Zhou S, Janke L, et al.
Interleukin-7 receptor mutants initiate early T cell precursor leukemia in murine thymocyte progenitors with multipotent potential.
J Exp Med. 2014; 211(4):701-13 [PubMed] Article available free on PMC after 01/01/2016 Related Publications
Early T cell precursor acute lymphoblastic leukemia (ETP-ALL) exhibits lymphoid, myeloid, and stem cell features and is associated with a poor prognosis. Whole genome sequencing of human ETP-ALL cases has identified recurrent mutations in signaling, histone modification, and hematopoietic development genes but it remains to be determined which of these abnormalities are sufficient to initiate leukemia. We show that activating mutations in the interleukin-7 receptor identified in human pediatric ETP-ALL cases are sufficient to generate ETP-ALL in mice transplanted with primitive transduced thymocytes from p19(Arf-/-) mice. The cellular mechanism by which these mutant receptors induce ETP-ALL is the block of thymocyte differentiation at the double negative 2 stage at which myeloid lineage and T lymphocyte developmental potential coexist. Analyses of samples from pediatric ETP-ALL cases and our murine ETP-ALL model show uniformly high levels of LMO2 expression, very low to undetectable levels of BCL11B expression, and a relative lack of activating NOTCH1 mutations. We report that pharmacological blockade of Jak-Stat signaling with ruxolitinib has significant antileukemic activity in this ETP-ALL model. This new murine model recapitulates several important cellular and molecular features of ETP-ALL and should be useful to further define novel therapeutic approaches for this aggressive leukemia.

Braun CJ, Boztug K, Paruzynski A, et al.
Gene therapy for Wiskott-Aldrich syndrome--long-term efficacy and genotoxicity.
Sci Transl Med. 2014; 6(227):227ra33 [PubMed] Related Publications
Wiskott-Aldrich syndrome (WAS) is characterized by microthrombocytopenia, immunodeficiency, autoimmunity, and susceptibility to malignancies. In our hematopoietic stem cell gene therapy (GT) trial using a γ-retroviral vector, 9 of 10 patients showed sustained engraftment and correction of WAS protein (WASP) expression in lymphoid and myeloid cells and platelets. GT resulted in partial or complete resolution of immunodeficiency, autoimmunity, and bleeding diathesis. Analysis of retroviral insertion sites revealed >140,000 unambiguous integration sites and a polyclonal pattern of hematopoiesis in all patients early after GT. Seven patients developed acute leukemia [one acute myeloid leukemia (AML), four T cell acute lymphoblastic leukemia (T-ALL), and two primary T-ALL with secondary AML associated with a dominant clone with vector integration at the LMO2 (six T-ALL), MDS1 (two AML), or MN1 (one AML) locus]. Cytogenetic analysis revealed additional genetic alterations such as chromosomal translocations. This study shows that hematopoietic stem cell GT for WAS is feasible and effective, but the use of γ-retroviral vectors is associated with a substantial risk of leukemogenesis.

Lossos C, Bayraktar S, Weinzierl E, et al.
LMO2 and BCL6 are associated with improved survival in primary central nervous system lymphoma.
Br J Haematol. 2014; 165(5):640-8 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
Primary central nervous system lymphoma (PCNSL) is an aggressive sub-variant of non-Hodgkin lymphoma (NHL) with morphological similarities to diffuse large B-cell lymphoma (DLBCL). While methotrexate (MTX)-based therapies have improved patient survival, the disease remains incurable in most cases and its pathogenesis is poorly understood. We evaluated 69 cases of PCNSL for the expression of HGAL (also known as GCSAM), LMO2 and BCL6 - genes associated with DLBCL prognosis and pathobiology, and analysed their correlation to survival in 49 PCNSL patients receiving MTX-based therapy. We demonstrate that PCNSL expresses LMO2, HGAL(also known as GCSAM) and BCL6 proteins in 52%, 65% and 56% of tumours, respectively. BCL6 protein expression was associated with longer progression-free survival (P = 0·006) and overall survival (OS, P = 0·05), while expression of LMO2 protein was associated with longer OS (P = 0·027). Further research is needed to elucidate the function of BCL6 and LMO2 in PCNSL.

Smith S, Tripathi R, Goodings C, et al.
LIM domain only-2 (LMO2) induces T-cell leukemia by two distinct pathways.
PLoS One. 2014; 9(1):e85883 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
The LMO2 oncogene is deregulated in the majority of human T-cell leukemia cases and in most gene therapy-induced T-cell leukemias. We made transgenic mice with enforced expression of Lmo2 in T-cells by the CD2 promoter/enhancer. These transgenic mice developed highly penetrant T-ALL by two distinct patterns of gene expression: one in which there was concordant activation of Lyl1, Hhex, and Mycn or alternatively, with Notch1 target gene activation. Most strikingly, this gene expression clustering was conserved in human Early T-cell Precursor ALL (ETP-ALL), where LMO2, HHEX, LYL1, and MYCN were most highly expressed. We discovered that HHEX is a direct transcriptional target of LMO2 consistent with its concordant gene expression. Furthermore, conditional inactivation of Hhex in CD2-Lmo2 transgenic mice markedly attenuated T-ALL development, demonstrating that Hhex is a crucial mediator of Lmo2's oncogenic function. The CD2-Lmo2 transgenic mice offer mechanistic insight into concordant oncogene expression and provide a model for the highly treatment-resistant ETP-ALL subtype.

Larmonie NS, van der Spek A, Bogers AJ, et al.
Genetic and epigenetic determinants mediate proneness of oncogene breakpoint sites for involvement in TCR translocations.
Genes Immun. 2014; 15(2):72-81 [PubMed] Related Publications
T-cell receptor (TCR) translocations are a genetic hallmark of T-cell acute lymphoblastic leukemia and lead to juxtaposition of oncogene and TCR loci. Oncogene loci become involved in translocations because they are accessible to the V(D)J recombination machinery. Such accessibility is predicted at cryptic recombination signal sequence (cRSS) sites ('Type 1') as well as other sites that are subject to DNA double-strand breaks (DSBs) ('Type 2') during early stages of thymocyte development. As chromatin accessibility markers have not been analyzed in the context of TCR-associated translocations, various genetic and epigenetic determinants of LMO2, TAL1 and TLX1 translocation breakpoint (BP) sites and BP cluster regions (BCRs) were examined in human thymocytes to establish DSB proneness and heterogeneity of BP site involvement in TCR translocations. Our data show that DSBs in BCRs are primarily induced in the presence of a genetic element of sequence vulnerability (cRSSs, transposable elements), whereas breaks at single BP sites lacking such elements are more likely induced by chance or perhaps because of patient-specific genetic vulnerability. Vulnerability to obtain DSBs is increased by features that determine chromatin organization, such as methylation status and nucleosome occupancy, although at different levels at different BP sites.

Klampfl T, Milosevic JD, Puda A, et al.
Complex patterns of chromosome 11 aberrations in myeloid malignancies target CBL, MLL, DDB1 and LMO2.
PLoS One. 2013; 8(10):e77819 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
Exome sequencing of primary tumors identifies complex somatic mutation patterns. Assignment of relevance of individual somatic mutations is difficult and poses the next challenge for interpretation of next generation sequencing data. Here we present an approach how exome sequencing in combination with SNP microarray data may identify targets of chromosomal aberrations in myeloid malignancies. The rationale of this approach is that hotspots of chromosomal aberrations might also harbor point mutations in the target genes of deletions, gains or uniparental disomies (UPDs). Chromosome 11 is a frequent target of lesions in myeloid malignancies. Therefore, we studied chromosome 11 in a total of 813 samples from 773 individual patients with different myeloid malignancies by SNP microarrays and complemented the data with exome sequencing in selected cases exhibiting chromosome 11 defects. We found gains, losses and UPDs of chromosome 11 in 52 of the 813 samples (6.4%). Chromosome 11q UPDs frequently associated with mutations of CBL. In one patient the 11qUPD amplified somatic mutations in both CBL and the DNA repair gene DDB1. A duplication within MLL exon 3 was detected in another patient with 11qUPD. We identified several common deleted regions (CDR) on chromosome 11. One of the CDRs associated with de novo acute myeloid leukemia (P=0.013). One patient with a deletion at the LMO2 locus harbored an additional point mutation on the other allele indicating that LMO2 might be a tumor suppressor frequently targeted by 11p deletions. Our chromosome-centered analysis indicates that chromosome 11 contains a number of tumor suppressor genes and that the role of this chromosome in myeloid malignancies is more complex than previously recognized.

Coutinho R, Clear AJ, Owen A, et al.
Poor concordance among nine immunohistochemistry classifiers of cell-of-origin for diffuse large B-cell lymphoma: implications for therapeutic strategies.
Clin Cancer Res. 2013; 19(24):6686-95 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
PURPOSE: The opportunity to improve therapeutic choices on the basis of molecular features of the tumor cells is on the horizon in diffuse large B-cell lymphoma (DLBCL). Agents such as bortezomib exhibit selective activity against the poor outcome activated B-cell type (ABC) DLBCL. In order for targeted therapies to succeed in this disease, robust strategies that segregate patients into molecular groups with high reliability are needed. Although molecular studies are considered gold standard, several immunohistochemistry (IHC) algorithms have been published that claim to be able to stratify patients according to their cell-of-origin and to be relevant for patient outcome. However, results are poorly reproducible by independent groups.
EXPERIMENTAL DESIGN: We investigated nine IHC algorithms for molecular classification in a dataset of DLBCL diagnostic biopsies, incorporating immunostaining for CD10, BCL6, BCL2, MUM1, FOXP1, GCET1, and LMO2. IHC profiles were assessed and agreed among three expert observers. A consensus matrix based on all scoring combinations and the number of subjects for each combination allowed us to assess reliability. The survival impact of individual markers and classifiers was evaluated using Kaplan-Meier curves and the log-rank test.
RESULTS: The concordance in patient's classification across the different algorithms was low. Only 4% of the tumors have been classified as germinal center B-cell type (GCB) and 21% as ABC/non-GCB by all methods. None of the algorithms provided prognostic information in the R-CHOP (rituximab plus cyclophosphamide-adriamycin-vincristine-prednisone)-treated cohort.
CONCLUSION: Further work is required to standardize IHC algorithms for DLBCL cell-of-origin classification for these to be considered reliable alternatives to molecular-based methods to be used for clinical decisions.

Sissolak G, Wood L, Smith L, et al.
Tissue microarray in a subset of South African patients with DLBCL.
Transfus Apher Sci. 2013; 49(2):120-32 [PubMed] Related Publications
Tissue samples from 93 de novo diffuse large B-cell lymphoma patients seen between 1995 and 2009 randomly receiving either standard combination chemotherapy (CHOP, n=48) or the identical program with rituximab (n=45) were subtyped using an investigational immunohistochemical (IHC) based tissue microarray (TMA) and contrasted to the approximately corresponding categories as defined either by Hans and associates using a three marker panel into germinal or non-germinal centre subtypes or by Choi and colleagues with two additional antibodies into germinal centre (GCB) or activated B-cells (ABC). Each of these primary subdivisions was further evaluated for expression of BCL2 and LMO2 both of which are recognised to predicate response. The addition of rituximab to the uniform drug regimen did not show any significant improvement in 5 years overall (63% versus 59%, p 0.68) or event-free survival (42% versus 39%, p 0.94), for CHOP versus R-CHOP comparisons. Similarly no differences were evident in subtype analysis. Interestingly however, when segregated on the Choi criteria, cytotoxic drugs alone showed a non-significant trend in improved survival (74% versus 55%, p 0.32) as well as event-free survival (44% versus 40%, p 0.42) for the germinal centre as opposed to the activated B-cell subtype. Nevertheless not even a small difference could be demonstrated in the presence of the anti CD 20 monoclonal antibody. According to Choi, both regimens (chemotherapy or immunotherapy antibody) revealed similar results to the Hans algorithm on 5 years OS as well as 3 year EFS when comparing GCB versus ABC or non-GCB subgroups. BCL2 and LMO2 marker expression of the respective immunohistochemical (IHC) subtype, despite small sample size, revealed the following. Analysis by Choi criteria on survival for BCL2, no matter for which subsets (GCB or ABC) or treatment modality (chemotherapy with or without the addition of rituximab) showed no difference in 5 years OS or EFS. In contrast, a significant difference for better EFS (p=0.0015) in the BCL2 positive group of the ABC subgroups subtypes treated with rituximab containing chemotherapy. For LMO2 similar results on survival outcome were seen thus showing no difference in 5 years OS or EFS - regardless of subtype or treatment modality. Also here, this was contrasted by better EFS (p=0.039) in the LMO2 positive group of ABC subtypes when treated with the rituximab containing regimen. The use of the IHC based TMA methodology has shown to be a simple, cost effective and a robust alternative to gene expression profiling (GEP) which is currently regarded as the gold standard for the classification in lymphomas. It provides a useful prognostic tool in stratifying DLBCL or other entities in future, even when frozen tissue samples are not available for GEP analysis. With the current budgetary limitations in South African public hospitals chemotherapy protocols for lymphoproliferative disorders exclude agents such as rituximab. Local therapeutic drug committees consider the approximately 15% overall survival benefit seen at 5 years for DLBCL when rituximab is added to combination chemotherapy as too marginal for justifying the arising additional expenses. Accordingly, demonstration that a specific molecular subtype accounts for superior outcome, when using these regimens, is needed. Such an option would provide convincing evidence for the use of immunochemotherapy in a resource constrained setting.

Wyspiańska BS, Bannister AJ, Barbieri I, et al.
BET protein inhibition shows efficacy against JAK2V617F-driven neoplasms.
Leukemia. 2014; 28(1):88-97 [PubMed] Related Publications
Small molecule inhibition of the BET family of proteins, which bind acetylated lysines within histones, has been shown to have a marked therapeutic benefit in pre-clinical models of mixed lineage leukemia (MLL) fusion protein-driven leukemias. Here, we report that I-BET151, a highly specific BET family bromodomain inhibitor, leads to growth inhibition in a human erythroleukemic (HEL) cell line as well as in erythroid precursors isolated from polycythemia vera patients. One of the genes most highly downregulated by I-BET151 was LMO2, an important oncogenic regulator of hematopoietic stem cell development and erythropoiesis. We previously reported that LMO2 transcription is dependent upon Janus kinase 2 (JAK2) kinase activity in HEL cells. Here, we show that the transcriptional changes induced by a JAK2 inhibitor (TG101209) and I-BET151 in HEL cells are significantly over-lapping, suggesting a common pathway of action. We generated JAK2 inhibitor resistant HEL cells and showed that these retain sensitivity to I-BET151. These data highlight I-BET151 as a potential alternative treatment against myeloproliferative neoplasms driven by constitutively active JAK2 kinase.

McCormack MP, Shields BJ, Jackson JT, et al.
Requirement for Lyl1 in a model of Lmo2-driven early T-cell precursor ALL.
Blood. 2013; 122(12):2093-103 [PubMed] Related Publications
Lmo2 is an oncogenic transcription factor that is frequently overexpressed in T-cell acute lymphoblastic leukemia (T-ALL), including early T-cell precursor ALL (ETP-ALL) cases with poor prognosis. Lmo2 must be recruited to DNA by binding to the hematopoietic basic helix-loop-helix factors Scl/Tal1 or Lyl1. However, it is unknown which of these factors can mediate the leukemic activity of Lmo2. To address this, we have generated Lmo2-transgenic mice lacking either Scl or Lyl1 in the thymus. We show that although Scl is dispensable for Lmo2-driven leukemia, Lyl1 is critical for all oncogenic functions of Lmo2, including upregulation of a stem cell-like gene signature, aberrant self-renewal of thymocytes, and subsequent generation of T-cell leukemia. Lyl1 expression is restricted to preleukemic and leukemic stem cell populations in this model, providing a molecular explanation for the stage-specific expression of the Lmo2-induced gene expression program. Moreover, LMO2 and LYL1 are coexpressed in ETP-ALL patient samples, and LYL1 is required for growth of ETP-ALL cell lines. Thus, the LMO2-LYL1 interaction is a promising therapeutic target for inhibiting self-renewing cancer stem cells in T-ALL, including poor-prognosis ETP-ALL cases.

Coma S, Allard-Ratick M, Akino T, et al.
GATA2 and Lmo2 control angiogenesis and lymphangiogenesis via direct transcriptional regulation of neuropilin-2.
Angiogenesis. 2013; 16(4):939-52 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
GATA-binding protein 2 (GATA2) and LIM domain only 2 (Lmo2) form common transcription complexes during hematopoietic differentiation. Here we show that these two transcription factors also play a key role in endothelial cells (EC) and lymphatic EC (LEC) function. Primary EC and tumor-associated blood vessels expressed GATA2 and Lmo2. VEGF-induced sprouting angiogenesis in both differentiating embryonic stem cells (embryoid bodies) and primary EC increased GATA2 and Lmo2 levels. Conversely, silencing of GATA2 and Lmo2 expression in primary EC inhibited VEGF-induced angiogenic activity, including EC migration and sprouting in vitro, two key steps of angiogenesis in vivo. This inhibition of EC function was associated with downregulated expression of neuropilin-2 (NRP2), a co-receptor of VEGFRs for VEGF, at the protein, mRNA and promoter levels. NRP2 overexpression partially rescued the impaired angiogenic sprouting in the GATA2/Lmo2 knockdown EC, confirming that GATA2 and Lmo2 mediated EC function, at least in part, by directly regulating NRP2 gene expression. Furthermore, it was found that primary LEC expressed GATA2 and Lmo2 as well. Silencing of GATA2 and Lmo2 expression in LEC inhibited VEGF-induced LEC sprouting, also in a NRP2-dependent manner. In conclusion, our results demonstrate that GATA2 and Lmo2 cooperatively regulate VEGF-induced angiogenesis and lymphangiogenesis via NRP2.

Zheng X, Naiditch J, Czurylo M, et al.
Differential effect of long-term drug selection with doxorubicin and vorinostat on neuroblastoma cells with cancer stem cell characteristics.
Cell Death Dis. 2013; 4:e740 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
Numerous studies have confirmed that cancer stem cells (CSCs) are more resistant to chemotherapy; however, there is a paucity of data exploring the effect of long-term drug treatment on the CSC sub-population. The purpose of this study was to investigate whether long-term doxorubicin treatment could expand the neuroblastoma cells with CSC characteristics and histone acetylation could affect stemness gene expression during the development of drug resistance. Using n-myc amplified SK-N-Be(2)C and non-n-myc amplified SK-N-SH human neuroblastoma cells, our laboratory generated doxorubicin-resistant cell lines in parallel over 1 year; one cell line intermittently treated with the histone deacetylase inhibitor (HDACi) vorinostat and the other without exposure to HDACi. Cells' sensitivity to chemotherapeutic drugs, the ability to form tumorspheres, and capacity for in vitro invasion were examined. Cell-surface markers and side populations (SPs) were analyzed using flow cytometry. Differentially expressed stemness genes were identified through whole genome analysis and confirmed with real-time PCR. Our results indicated that vorinostat increased the sensitivity of only SK-N-Be(2)C-resistant cells to chemotherapy, made cells lose the ability to form tumorspheres, and reduced in vitro invasion and the SP percentage. CD133 was not enriched in doxorubicin-resistant or vorinostat-treated doxorubicin-resistant cells. Nine stemness-linked genes (ABCB1, ABCC4, LMO2, SOX2, ERCC5, S100A10, IGFBP3, TCF3, and VIM) were downregulated in vorinostat-treated doxorubicin-resistant SK-N-Be(2)C cells relative to doxorubicin-resistant cells. A sub-population of cells with CSC characteristics is enriched during prolonged drug selection of n-myc amplified SK-N-Be(2)C neuroblastoma cells. Vorinostat treatment affects the reversal of drug resistance in SK-N-Be(2)C cells and may be associated with downregulation of stemness gene expression. This work may be valuable for clinicians to design treatment protocols specific for different neuroblastoma patients.

Saki N, Abroun S, Soleimani M, et al.
The roles of miR-146a in the differentiation of Jurkat T-lymphoblasts.
Hematology. 2014; 19(3):141-7 [PubMed] Related Publications
INTRODUCTION: T-cell acute lymphoblastic leukemia (T-ALL) is caused by a defect in T-cell maturation to the mature T cell. T-ALL is a poor prognostic hematopoietic malignancy. In order to establish a successful therapeutic treatment plan, it is essential to understand the biology of T-cell development and molecules that contribute to this process. This study uses Jurkat T cells, as a well-established model for in vitro study of T-ALL to investigate the role of the microRNA (miRNA), miR-146a, on gene expressions involved in T-cell differentiation.
MATERIALS AND METHODS: The permanent over-expression of miR-146a was established using a lentivector that expressed GFP hsa-mir-146a miRNA. We used quantitative real-time polymerase chain reaction and flow cytometry for T-cell differentiation to monitor induction of the differentiation process by assessing changes in expression of some distinct transcription factors and cell surface markers.
RESULTS: Ectopic expression of miR-146a resulted in significant up-regulation of PU.1, c-Fos, CCAAT/enhancer-binding protein alpha (C/EBPα) and GATA3, and slight up-regulation of Foxp3 and Runx1. There was a significant, moderate down-regulation in the expressions of Notch1, LIM-domain only (Lmo2), son of sevenless 1 (SOS1), Ikaros, and signal transducer and activator of transcription 3 (STAT3).
CONCLUSION: Our results indicated that ectopic expression of miR-146a could not independently induce differentiation in lymphoblastic cells. However, the expression of multiple genes involved in T-cell differentiation and T-cell CD markers were found to be affected. These results have suggested a potential tumor suppressive, immunomodulatory and cell activator role for miR146-a.

Calero-Nieto FJ, Joshi A, Bonadies N, et al.
HOX-mediated LMO2 expression in embryonic mesoderm is recapitulated in acute leukaemias.
Oncogene. 2013; 32(48):5471-80 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
The Lim Domain Only 2 (LMO2) leukaemia oncogene encodes an LIM domain transcriptional cofactor required for early haematopoiesis. During embryogenesis, LMO2 is also expressed in developing tail and limb buds, an expression pattern we now show to be recapitulated in transgenic mice by an enhancer in LMO2 intron 4. Limb bud expression depended on a cluster of HOX binding sites, while posterior tail expression required the HOX sites and two E-boxes. Given the importance of both LMO2 and HOX genes in acute leukaemias, we further demonstrated that the regulatory hierarchy of HOX control of LMO2 is activated in leukaemia mouse models as well as in patient samples. Moreover, Lmo2 knock-down impaired the growth of leukaemic cells, and high LMO2 expression at diagnosis correlated with poor survival in cytogenetically normal AML patients. Taken together, these results establish a regulatory hierarchy of HOX control of LMO2 in normal development, which can be resurrected during leukaemia development. Redeployment of embryonic regulatory hierarchies in an aberrant context is likely to be relevant in human pathologies beyond the specific example of ectopic activation of LMO2.

Paul AG, Chandran B, Sharma-Walia N
Cyclooxygenase-2-prostaglandin E2-eicosanoid receptor inflammatory axis: a key player in Kaposi's sarcoma-associated herpes virus associated malignancies.
Transl Res. 2013; 162(2):77-92 [PubMed] Related Publications
The role of cyclooxygenase-2 (COX-2), its lipid metabolite prostaglandin E2 (PGE2), and Eicosanoid (EP) receptors (EP; 1-4) underlying the proinflammatory mechanistic aspects of Burkitt's lymphoma, nasopharyngeal carcinoma, cervical cancer, prostate cancer, colon cancer, and Kaposi's sarcoma (KS) is an active area of investigation. The tumorigenic potential of COX-2 and PGE2 through EP receptors forms the mechanistic context underlying the chemotherapeutic potential of nonsteroidal anti-inflammatory drugs (NSAIDs). Although role of the COX-2 is described in several viral associated malignancies, the biological significance of the COX-2/PGE2/EP receptor inflammatory axis is extensively studied only in Kaposi's sarcoma-associated herpes virus (KSHV/HHV-8) associated malignancies such as KS, a multifocal endothelial cell tumor and primary effusion lymphoma (PEL), a B cell-proliferative disorder. The purpose of this review is to summarize the salient findings delineating the molecular mechanisms downstream of COX-2 involving PGE2 secretion and its autocrine and paracrine interactions with EP receptors (EP1-4), COX-2/PGE2/EP receptor signaling regulating KSHV pathogenesis and latency. KSHV infection induces COX-2, PGE2 secretion, and EP receptor activation. The resulting signal cascades modulate the expression of KSHV latency genes (latency associated nuclear antigen-1 [LANA-1] and viral-Fas (TNFRSF6)-associated via death domain like interferon converting enzyme-like- inhibitory protein [vFLIP]). vFLIP was also shown to be crucial for the maintenance of COX-2 activation. The mutually interdependent interactions between viral proteins (LANA-1/vFLIP) and COX-2/PGE2/EP receptors was shown to play key roles in the biological mechanisms involved in KS and PEL pathogenesis such as blockage of apoptosis, cell cycle regulation, transformation, proliferation, angiogenesis, adhesion, invasion, and immune-suppression. Understanding the COX-2/PGE2/EP axis is very important to develop new safer and specific therapeutic modalities for KS and PEL. In addition to COX-2 being a therapeutic target, EP receptors represent ideal targets for pharmacologic agents as PGE2 analogues and their blockers/antagonists possess antineoplastic activity, without the reported gastrointestinal and cardiovascular toxicity observed with few a NSAIDs.

Shen LJ, Chen FY, Zhang Y, et al.
MYCN transgenic zebrafish model with the characterization of acute myeloid leukemia and altered hematopoiesis.
PLoS One. 2013; 8(3):e59070 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
BACKGROUND: Amplification of MYCN (N-Myc) oncogene has been reported as a frequent event and a poor prognostic marker in human acute myeloid leukemia (AML). The molecular mechanisms and transcriptional networks by which MYCN exerts its influence in AML are largely unknown.
METHODOLOGY/PRINCIPAL FINDINGS: We introduced murine MYCN gene into embryonic zebrafish through a heat-shock promoter and established the stable germline Tg(MYCN:HSE:EGFP) zebrafish. N-Myc downstream regulated gene 1 (NDRG1), negatively controlled by MYCN in human and functionally involved in neutrophil maturation, was significantly under-expressed in this model. Using peripheral blood smear detection, histological section and flow cytometric analysis of single cell suspension from kidney and spleen, we found that MYCN overexpression promoted cell proliferation, enhanced the repopulating activity of myeloid cells and the accumulation of immature hematopoietic blast cells. MYCN enhanced primitive hematopoiesis by upregulating scl and lmo2 expression and promoted myelopoiesis by inhibiting gata1 expression and inducing pu.1, mpo expression. Microarray analysis identified that cell cycle, glycolysis/gluconeogenesis, MAPK/Ras, and p53-mediated apoptosis pathways were upregulated. In addition, mismatch repair, transforming and growth factor β (TGFβ) were downregulated in MYCN-overexpressing blood cells (p<0.01). All of these signaling pathways are critical in the proliferation and malignant transformation of blood cells.
CONCLUSION/SIGNIFICANCE: The above results induced by overexpression of MYCN closely resemble the main aspects of human AML, suggesting that MYCN plays a role in the etiology of AML. MYCN reprograms hematopoietic cell fate by regulating NDRG1 and several lineage-specific hematopoietic transcription factors. Therefore, this MYCN transgenic zebrafish model facilitates dissection of MYCN-mediated signaling in vivo, and enables high-throughput scale screens to identify the potential therapeutic targets.

Diffner E, Beck D, Gudgin E, et al.
Activity of a heptad of transcription factors is associated with stem cell programs and clinical outcome in acute myeloid leukemia.
Blood. 2013; 121(12):2289-300 [PubMed] Related Publications
Aberrant transcriptional programs in combination with abnormal proliferative signaling drive leukemic transformation. These programs operate in normal hematopoiesis where they are involved in hematopoietic stem cell (HSC) proliferation and maintenance. Ets Related Gene (ERG) is a component of normal and leukemic stem cell signatures and high ERG expression is a risk factor for poor prognosis in acute myeloid leukemia (AML). However, mechanisms that underlie ERG expression in AML and how its expression relates to leukemic stemness are unknown. We report that ERG expression in AML is associated with activity of the ERG promoters and +85 stem cell enhancer and a heptad of transcription factors that combinatorially regulate genes in HSCs. Gene expression signatures derived from ERG promoter-stem cell enhancer and heptad activity are associated with clinical outcome when ERG expression alone fails. We also show that the heptad signature is associated with AMLs that lack somatic mutations in NPM1 and confers an adverse prognosis when associated with FLT3 mutations. Taken together, these results suggest that transcriptional regulators cooperate to establish or maintain primitive stem cell-like signatures in leukemic cells and that the underlying pattern of somatic mutations contributes to the development of these signatures and modulate their influence on clinical outcome.

Joshi A, Hannah R, Diamanti E, Göttgens B
Gene set control analysis predicts hematopoietic control mechanisms from genome-wide transcription factor binding data.
Exp Hematol. 2013; 41(4):354-66.e14 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
Transcription factors are key regulators of both normal and malignant hematopoiesis. Chromatin immunoprecipitation (ChIP) coupled with high-throughput sequencing (ChIP-Seq) has become the method of choice to interrogate the genome-wide effect of transcription factors. We have collected and integrated 142 publicly available ChIP-Seq datasets for both normal and leukemic murine blood cell types. In addition, we introduce the new bioinformatic tool Gene Set Control Analysis (GSCA). GSCA predicts likely upstream regulators for lists of genes based on statistical significance of binding event enrichment within the gene loci of a user-supplied gene set. We show that GSCA analysis of lineage-restricted gene sets reveals expected and previously unrecognized candidate upstream regulators. Moreover, application of GSCA to leukemic gene sets allowed us to predict the reactivation of blood stem cell control mechanisms as a likely contributor to LMO2 driven leukemia. It also allowed us to clarify the recent debate on the role of Myc in leukemia stem cell transcriptional programs. As a result, GSCA provides a valuable new addition to analyzing gene sets of interest, complementary to Gene Ontology and Gene Set Enrichment analyses. To facilitate access to the wider research community, we have implemented GSCA as a freely accessible web tool (http://bioinformatics.cscr.cam.ac.uk/GSCA/GSCA.html).

Sever T, Kilicarslan C, Pehlivan M, et al.
Research on and clinical importance of duplications in various chromosomal regions in addition to Philadelphia chromosome in chronic myeloid leukemia.
J BUON. 2012 Jul-Sep; 17(3):490-6 [PubMed] Related Publications
PURPOSE: To investigate the chromosomal aberrations in chronic myelogenous leukemia (CML), particularly in chromosomal regions which carried 67 genes pertaining to oncogenes, transcription factors, signal transduction, tumor suppressors, apoptosis etc, in addition to Philadelphia (Ph+) chromosome by multiplex ligation-dependent probe amplification (MLPA) method and to compare them with clinical parameters.
METHODS: The aberrations were investigated in 48 CML patients receiving imatinib therapy and a group of 15 healthy controls, by using the MLPA method between 2000 and 2009. The obtained results were compared both between patient and control groups and with clinical parameters.
RESULTS: Duplication was detected in the fibroblast growth factor receptor 1 (FGFR1) gene of 2 patients, inosine 5' monophosphate dehydrogenase 1 (IMPDH1) gene of 4, postmeiotic segregation increased S. Cerevisiae 2 (PMS2) gene of 1, nuclear factor kappa beta (NFKB) of 5 and T-cell translocation 2 (LMO2) gene of 1 patient. Univariate analysis showed that splenomegaly, advanced age, Sokal risk score (SRS) and the duplications in IMPDH1 and FGFR1 genes significantly shortened 7-year event-free survival (EFS); multivariate analysis showed that only the duplications in IMPDH1 and FGFR1 genes were the factors that significantly affected EFS. No statistically significant correlations were detected between duplications and other clinical parameters.
CONCLUSION: Duplications in 4 genes (FGFR1, IMPDH1, PMS2, LMO2) in addition to Ph+ chromosome in CML patients were detected for the first time. This study indicates that chromosomes 7 and 8 should be particularly investigated in more detail in addition to the Ph+ chromosome for better determination of disease prognosis and selection of alternative treatments.

San-Marina S, Han Y, Liu J, Minden MD
Suspected leukemia oncoproteins CREB1 and LYL1 regulate Op18/STMN1 expression.
Biochim Biophys Acta. 2012 Nov-Dec; 1819(11-12):1164-72 [PubMed] Related Publications
Stathmin (STMN1) is a microtubule destabilizing protein with a key role in cell cycle progression and cell migration that is up-regulated in several cancers and may contribute to the malignant phenotype. However, the factors that regulate its expression are not well understood. Loss as well as gain-of-function p53 mutations up-regulate STMN1 and in acute myelogenous leukemia where p53 is predominantly wild-type, STMN1 is also over-expressed. Here we show regulatory control of STMN1 expression by the leucine zipper transcription factor (TF) CREB1 and the basic helix-loop-helix TF LYL1. By ChIP-chip experiments we demonstrate in vivo the presence of LYL1 and CREB1 in close proximity on the STMN1 promoter and using promoter assays we reveal co-regulation of STMN1 by CREB1 and LYL1. By contrast, TAL1, another suspected oncoprotein in leukemia and close relative of LYL1, exerts no regulatory effect on the STMN1 promoter. NLI, LMO2 and GATA2 are previously described co-activators of Tal1/Lyl1-E47 transcriptional complexes and potentiate Lyl1 activation of the STMN1 promoter while having no effect on TAL1 transactivation. Promoter mutations that abrogate CREB1 proximal binding or mutations of the DNA-binding domain of CREB1 abolish LYL1 transcriptional activation. These results show that CRE and Ebox sites function as coordinated units and support previous evidence of joint CREB1-and LYL1 transcription events activating an aberrant subset of promoters in leukemia. CREB1 or LYL1 shRNA knock-down down-regulate STMN1 expression. Because down-regulation of STMN1 has been shown to have anti-proliferative effects, while CREB1 and LYL1 are suspected oncoproteins, interference with CREB1-LYL1 interactions may complement standard chemotherapy and yield additional beneficial effects.

Chapman-Fredricks J, Younes SF, Fan YS, et al.
Usefulness of HGAL and LMO2 immunohistochemistry in the identification of follicular lymphomas of the non-gastric gastrointestinal tract.
Appl Immunohistochem Mol Morphol. 2013; 21(3):200-4 [PubMed] Related Publications
BACKGROUND: We studied the sensitivity of 2 relatively new markers of germinal center B-cell origin, namely human germinal center-associated lymphoma (HGAL) and Lim-only transcription factor 2 (LMO2), in the identification of follicular lymphomas (FLs) of the nongastric gastrointestinal (GI) tract.
MATERIALS AND METHODS: We retrospectively reviewed cases of endoscopically derived primary, nongastric GI lymphomas including FL, grade 1 or 2, and extranodal marginal zone lymphoma (ENMZL) of mucosa-associated lymphoid tissue, classified based on morphologic features and immunohistochemical analysis. HGAL and LMO2 immunohistochemical stains were then prospectively performed in each case. When discrepant immunohistochemical results were obtained, fluorescent in situ hybridization was performed for t(14;18) IGH/BCL2 and IGH rearrangement using a dual color fusion and a dual color break-apart probe, respectively.
RESULTS: All but one of the CD10-negative ENMZL cases were negative for both HGAL and LMO2. One case originally classified as ENMZL was positive for both HGAL and LMO2. Fluorescent in situ hybridization did not detect either t(14;18) IGH/BCL2 or IGH rearrangement in this case. It is likely, based on positivity of 2 established germinal center B-cell markers, that this represents a FL which was originally misclassified as an ENMZL based on CD10 negativity. Of the cases of FL (all CD10 and/or BCL-6 positive), 8 (80%) were positive for both HGAL and LMO2.
CONCLUSIONS: Although HGAL and LMO2 did not demonstrate an increased sensitivity in the identification of FL of the nongastric GI tract in this series, they still were helpful in the reclassification of one of our cases, and may therefore be useful adjuncts in the identification of FL of the nongastric GI tract.

Son HJ, Kim JY, Hahn Y, Seo SB
Negative regulation of JAK2 by H3K9 methyltransferase G9a in leukemia.
Mol Cell Biol. 2012; 32(18):3681-94 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
Histone methylation at specific lysine residues is a crucial regulatory process in transcriptional regulation. Using chromatin immunoprecipitation with microarray technology (ChIP-chip) analysis, we found that the H3K9-me2 target gene JAK2 was an important factor during differentiation of the HL-60 promyelocytic leukemia cell line by all-trans-retinoic acid (ATRA) treatment. Here, we report that the H3K9 methyltransferase G9a negatively regulated JAK2 transcription in histone methyltransferase activity and in a YY1-dependent manner during ATRA-mediated leukemia cell differentiation. We found that G9a knockdown repressed ATRA-mediated HL-60 cell differentiation. We demonstrated that G9a interacts with YY1 and is recruited to the JAK2 promoter along with corepressors, including histone deacetylase, that induced H3K9-me2. Repression of JAK2 transcription by G9a decreased H3Y41 phosphorylation and promoted inhibition of the recently identified JAK2-H3Y41P-HP1α pathway-mediated leukemogenesis.

Shams TM
High expression of LMO2 in Hodgkin, Burkitt and germinal center diffuse large B cell lymphomas.
J Egypt Natl Canc Inst. 2011; 23(4):147-53 [PubMed] Related Publications
BACKGROUND AND AIM: The LMO2 gene encodes a transcription factor that regulates key events in erythropoiesis, angiogenesis, and embryogenesis and is highly expressed at the most immature stages of lymphopoiesis. Its implication in Hodgkin lymphoma (HL), Burkitt lymphoma (BL) and diffuse large B cell lymphoma (DLBCL) is limited in the literature.
MATERIAL AND METHODS: An immunohistochemical study was performed on 68 lymphoma specimens showing different types including Hodgkin lymphoma (23), Burkitt lymphoma (10) and diffuse large B cell lymphoma (35). Also, seven specimens of the reactive nodal tissue were included as control. A monoclonal anti-human antibody has been used to detect LMO2.
RESULTS: LMO2 was detected in all cases of HL (100%), in nine cases of BL (90%) and in all cases of DLBCL of germinal center (GC) subtype 20/35 (57.1%) but is completely negative in non-germinal center (NGC) DLBCL. In normal control of reactive nodes, LMO2 was expressed in germinal center area but not expressed in other areas including mantle, marginal, or T cell zones. In DLBCL; there was no statistically significant relation between LMO2 positive cases and the studied clinicopathological parameters including patient's age, sex and tumor site, stage and histological subtype. On the other hand, it was statistically significant regarding immunophenotyping of GC versus NGC.
CONCLUSIONS: LMO2 expression is a special feature of GC DLBCL which can be used as a diagnostic marker and therapeutic target. Further studies regarding its prognostic role in patients are recommended.

Chao C, Silverberg MJ, Martínez-Maza O, et al.
Epstein-Barr virus infection and expression of B-cell oncogenic markers in HIV-related diffuse large B-cell Lymphoma.
Clin Cancer Res. 2012; 18(17):4702-12 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
PURPOSE: Epstein-Barr virus (EBV)-mediated lymphomagenesis in the setting of HIV infection has been widely accepted. However, little is known about how EBV impacts prognosis. We investigated the hypothesis that EBV infection is associated with expression of specific B-cell oncogenic markers in HIV-related diffuse large B-cell lymphoma (DLBCL) and examined the prognostic use of detecting EBV infection.
EXPERIMENTAL DESIGN: HIV-related DLBCL cases diagnosed between 1996 and 2007 within Kaiser Permanente California were identified. Immunohistochemical staining was used to analyze the expression of selected markers that are cell-cycle regulators, B-cell activators, and antiapoptotic proteins among others. EBV infection was determined by in situ hybridization of EBV RNA. Correlations between EBV and marker expression were examined using Spearman correlation coefficient. The prognostic use of EBV status was examined in multivariable Cox model adjusting for International Prognostic Index (IPI). Receiver-operating characteristics (ROC) analysis was used to evaluate improvement in model discrimination.
RESULTS: Seventy HIV-related DLBCL cases were included (31% EBV±). EBV+ tumor was associated with increased expression of BLIMP1 and CD30 and reduced expression of BCL6 and LMO2. EBV+ tumor was independently associated with elevated 2-year overall mortality [HR, 3.3; 95% confidence interval (CI), 1.6-6.6]. Area under the ROC curve showed improved model discrimination when incorporating tumor EBV status with IPI in the prediction model [0.65 vs. 0.74 (IPI only)].
CONCLUSION: Our results suggest that EBV infection was associated with expression of several tumor markers that are involved in the NF-κB pathway and that detecting tumor EBV status may have prognostic use in HIV-related DLBCLs.

Kim JY, Kim KB, Eom GH, et al.
KDM3B is the H3K9 demethylase involved in transcriptional activation of lmo2 in leukemia.
Mol Cell Biol. 2012; 32(14):2917-33 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
Histone lysine methylation and demethylation are considered critical steps in transcriptional regulation. In this report, we performed chromatin immunoprecipitation with microarray technology (ChIP-chip) analysis to examine the genome-wide occupancy of H3K9-me2 during all-trans-retinoic acid (ATRA)-induced differentiation of HL-60 promyelocytic leukemia cells. Using this approach, we found that KDM3B, which contains a JmjC domain, was downregulated during differentiation through the recruitment of a corepressor complex. Furthermore, KDM3B displayed histone H3K9-me1/2 demethylase activity and induced leukemogenic oncogene lmo2 expression via a synergistic interaction with CBP. Here, we found that KDM3B repressed leukemia cell differentiation and was upregulated in blood cells from acute lymphoblastic leukemia (ALL)-type leukemia patients. The combined results of this study provide evidence that the H3K9-me1/2 demethylase KDM3B might play a role in leukemogenesis via activation of lmo2 through interdependent actions with the histone acetyltransferase (HAT) complex containing CBP.

Cubedo E, Gentles AJ, Huang C, et al.
Identification of LMO2 transcriptome and interactome in diffuse large B-cell lymphoma.
Blood. 2012; 119(23):5478-91 [PubMed] Article available free on PMC after 01/06/2015 Related Publications
LMO2 regulates gene expression by facilitating the formation of multipartite DNA-binding complexes. In B cells, LMO2 is specifically up-regulated in the germinal center (GC) and is expressed in GC-derived non-Hodgkin lymphomas. LMO2 is one of the most powerful prognostic indicators in diffuse large B-cell (DLBCL) patients. However, its function in GC B cells and DLBCL is currently unknown. In this study, we characterized the LMO2 transcriptome and transcriptional complex in DLBCL cells. LMO2 regulates genes implicated in kinetochore function, chromosome assembly, and mitosis. Overexpression of LMO2 in DLBCL cell lines results in centrosome amplification. In DLBCL, the LMO2 complex contains some of the traditional partners, such as LDB1, E2A, HEB, Lyl1, ETO2, and SP1, but not TAL1 or GATA proteins. Furthermore, we identified novel LMO2 interacting partners: ELK1, nuclear factor of activated T-cells (NFATc1), and lymphoid enhancer-binding factor1 (LEF1) proteins. Reporter assays revealed that LMO2 increases transcriptional activity of NFATc1 and decreases transcriptional activity of LEF1 proteins. Overall, our studies identified a novel LMO2 transcriptome and interactome in DLBCL and provides a platform for future elucidation of LMO2 function in GC B cells and DLBCL pathogenesis.

Arribas AJ, Campos-Martín Y, Gómez-Abad C, et al.
Nodal marginal zone lymphoma: gene expression and miRNA profiling identify diagnostic markers and potential therapeutic targets.
Blood. 2012; 119(3):e9-e21 [PubMed] Related Publications
Nodal marginal zone lymphoma (NMZL) is a small B-cell neoplasm whose molecular pathogenesis is still essentially unknown and whose differentiation from other small B-cell lymphomas is hampered by the lack of specific markers. We have analyzed gene expression, miRNA profile, and copy number data from 15 NMZL cases. For comparison, 16 follicular lymphomas (FLs), 9 extranodal marginal zone lymphomas, and 8 reactive lymph nodes and B-cell subtypes were included. The results were validated by quantitative RT-PCR in an independent series, including 61 paraffin-embedded NMZLs. NMZL signature showed an enriched expression of gene sets identifying interleukins, integrins, CD40, PI3K, NF-κB, and TGF-β, and included genes expressed by normal marginal zone cells and memory B cells. The most highly overexpressed genes were SYK, TACI, CD74, CD82, and CDC42EP5. Genes linked to G(2)/M and germinal center were down-regulated. Comparison of the gene expression profiles of NMZL and FL showed enriched expression of CHIT1, TGFB1, and TACI in NMZL, and BCL6, LMO2, and CD10 in FL. NMZL displayed increased expression of miR-221, miR-223, and let-7f, whereas FL strongly expressed miR-494. Our study identifies new candidate diagnostic molecules for NMZL and reveals survival pathways activated in NMZL.

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