TAL1; T-cell acute lymphocytic leukemia 1 (1p32)

Gene Summary

Gene:TAL1; T-cell acute lymphocytic leukemia 1
Aliases: SCL, TCL5, tal-1, bHLHa17
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:T-cell acute lymphocytic leukemia protein 1
Updated:14 December, 2014


What does this gene/protein do?
Show (45)

Cancer Overview

Research Indicators

Publications Per Year (1989-2014)
Graph generated 14 December 2014 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.

  • Amino Acid Sequence
  • Proto-Oncogenes
  • TAL1
  • Gene Rearrangement
  • Gene Expression Profiling
  • Signal Transducing Adaptor Proteins
  • Messenger RNA
  • Leukemic Gene Expression Regulation
  • Mice, Transgenic
  • Polymerase Chain Reaction
  • Precursor T-Cell Lymphoblastic Leukemia-Lymphoma
  • Base Sequence
  • Chromosome 1
  • Hematopoiesis
  • Homeodomain Proteins
  • Cell Differentiation
  • T-Lymphocytes
  • Promoter Regions
  • Leukaemia
  • Gene Deletion
  • Mutation
  • Infant
  • DNA-Binding Proteins
  • Cancer DNA
  • Neoplastic Cell Transformation
  • Immunophenotyping
  • Childhood Cancer
  • Adolescents
  • Cancer Gene Expression Regulation
  • Helix-Loop-Helix Motifs
  • Neoplasm Proteins
  • Adult T-Cell Leukemia-Lymphoma
  • Molecular Sequence Data
  • Oncogene Fusion Proteins
  • Acute Lymphocytic Leukaemia
  • Proto-Oncogene Proteins
  • LIM Domain Proteins
  • Basic Helix-Loop-Helix Transcription Factors
  • Sequence Deletion
  • Metalloproteins
Tag cloud generated 14 December, 2014 using data from PubMed, MeSH and CancerIndex

Notable (2)

Scope includes mutations and abnormal protein expression.

Entity Topic PubMed Papers
Acute Lymphocytic Leukemia (ALL), childTAL1 and Childhood Leukemia View Publications68
Acute Lymphocytic Leukaemia (ALL)TAL1 and Acute Lymphocytic Leukaemia View Publications23

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

Related Links

Latest Publications: TAL1 (cancer-related)

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.

Related: PTEN LMO2 gene

Prange KH, Singh AA, Martens JH
The genome-wide molecular signature of transcription factors in leukemia.
Exp Hematol. 2014; 42(8):637-50 [PubMed] Related Publications
Transcription factors control expression of genes essential for the normal functioning of the hematopoietic system and regulate development of distinct blood cell types. During leukemogenesis, aberrant regulation of transcription factors such as RUNX1, CBFβ, MLL, C/EBPα, SPI1, GATA, and TAL1 is central to the disease. Here, we will discuss the mechanisms of transcription factor deregulation in leukemia and how in recent years next-generation sequencing approaches have helped to elucidate the molecular role of many of these aberrantly expressed transcription factors. We will focus on the complexes in which these factors reside, the role of posttranslational modification of these factors, their involvement in setting up higher order chromatin structures, and their influence on the local epigenetic environment. We suggest that only comprehensive knowledge on all these aspects will increase our understanding of aberrant gene expression in leukemia as well as open new entry points for therapeutic intervention.

Related: Leukemia

Chapiro E, Antony-Debre I, Marchay N, et al.
Sex chromosome loss may represent a disease-associated clonal population in chronic lymphocytic leukemia.
Genes Chromosomes Cancer. 2014; 53(3):240-7 [PubMed] Related Publications
Whether sex chromosome loss (SCL) is an age-related phenomenon or a cytogenetic marker of hematological disease is unclear. To address this issue in chronic lymphocytic leukemia (CLL), we investigated 20 cases with X or Y chromosome loss detected by conventional cytogenetics (CC). The frequency of SCL was low in CLL (2.3%). It was the sole abnormality, as detected by CC, in 10/20 (50%) patients. Fluorescence in situ hybridization (FISH) analyses confirmed SCL in all patients tested, present in 5-88% of cells (median: 68%). Deletions of 13q were observed by FISH in 16/20 (80%) patients. Compared with CLL without SCL, SCL was significantly associated with 13q deletion, especially when bi-allelic (P = 0.04). Co-hybridization analyses showed that SCL could be a concomitant, primary or secondary change, or be present in an independent clone. FISH analyses were performed on blood sub-populations isolated by Ficoll or flow cytometry. Comparing mononuclear cells (including CLL cells) and polynuclear cells separated by Ficoll, a maximum of 2% of polynuclear cells were found with SCL, whereas mononuclear cells exhibited a significantly higher loss frequency (range: 6-87%) (P = 0.03). Comparing B-cells (including CLL cells) and T-cells sorted by flow cytometry, the proportion of B-CD19+ cells with SCL was significantly higher (range: 88-96%) than that observed in T-CD3+ cells (range: 2-6%) (P = 0.008). We conclude that SCL has to be considered as a clonal aberration in CLL that may participate in the oncogenic process.

Related: Chromosome 13 Chromosome X Chromosome Y Chronic Lymphocytic Leukemia (CLL) CLL - Molecular Biology

Zheng H, Wang X, Ma Y, et al.
The TCR γδ repertoire and relative gene expression characteristics of T-ALL cases with biclonal malignant Vδ1 and Vδ2 T cells.
DNA Cell Biol. 2014; 33(1):49-56 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
Despite significant improvement in our understanding of T-cell acute lymphoblastic leukemia (T-ALL) biology and pathogenesis, many questions remain unanswered. In previous studies, we found a T-ALL case with two malignant T-cell clones with Vδ1Dδ2Dδ3Jδ1 and Vδ2Dδ3Jδ2 rearrangements. In this study, we further characterized T-ALL cases with two malignant clones containing Vδ1Dδ3Jδ1 and Vδ2Dδ1Jδ1 rearrangements using fine-tiling array comparative genomic hybridization, ligation-mediated polymerase chain reaction (LM-PCR), sequencing, and reverse transcription polymerase chain reaction (RT-PCR) analysis. We further analyzed the distribution and clonality of the T-cell receptor (TCR) Vγ and Vδ subfamily T cells in the two T-ALL cases by RT-PCR and GeneScan. Monoclonal Vδ1 and Vδ2 subfamilies were confirmed in both samples, the Vδ3 through Vδ7 subfamilies could not be detected in the T-ALL samples, whereas the oligoclonal Vδ8 subfamily could be identified. Based on the clinical finding that both of the T-ALL cases with two malignant T-cell clones had a poor outcome, we attempted to compare the expression pattern of genes related to T-cell activation and proliferation between cases with the malignant Vδ1 and Vδ2 T-cell clones and T-ALL cases with a mono-malignant Vα T-cell clone. We selected two T-ALL cases with VαJα rearrangements and analyzed the expression level of Notch1, TAL1, and the CARMA-BCL10-MALT-A20-NF-κB pathway genes by real-time PCR. A20 had significantly higher expression in the biclonal compared with the monoclonal T-ALL group (p=0.0354), and there was a trend toward higher expression for the other genes in the biclonal group with the exception of TAL1, although the differences were not statistically significant. In conclusion, we identified two T-ALL cases with biclonal malignant T-cell clones and described the characteristics of the biclonal T-ALL subtype and its gene expression pattern. Thus, our findings may improve the understanding of biclonal T-ALL.

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.

Related: LMO2 gene

Loosveld M, Bonnet M, Gon S, et al.
MYC fails to efficiently shape malignant transformation in T-cell acute lymphoblastic leukemia.
Genes Chromosomes Cancer. 2014; 53(1):52-66 [PubMed] Related Publications
MYC is a potent oncogene involved in ∼70% of human cancers, inducing tumorigenesis with high penetrance and short latency in experimental transgenic models. Accordingly, MYC is recognized as a major driver of T-cell acute lymphoblastic leukemia (T-ALL) in human and zebrafish/mouse models, and uncovering the context by which MYC-mediated malignant transformation initiates and develops remains a considerable challenge. Because MYC is a very complex oncogene, highly dependent on the microenvironment and cell-intrinsic context, we generated transgenic mice (tgMyc(spo)) in which ectopic Myc activation occurs sporadically (<10(-6) thymocytes) within otherwise normal thymic environment, thereby mimicking the unicellular context in which oncogenic alterations initiate human tumors. We show that while Myc(+) clones in tgMyc(spo) mice develop and initially proliferate in thymus and the periphery, no tumor or clonal expansion progress in aging mice (n = 130), suggesting an unexpectedly low ability of Myc to initiate efficient tumorigenesis. Furthermore, to determine the relevance of this observation in human pathogenesis we analyzed a human T-ALL case at diagnosis and relapse using the molecular stigmata of V(D)J recombination as markers of malignant progression; we similarly demonstrate that despite the occurrence of TAL1 and MYC translocations in early thymocyte ontogeny, subsequent oncogenic alterations were required to drive oncogenesis. Altogether, our data suggest that although central to T-ALL, MYC overexpression per se is inefficient in triggering the cascade of events leading to malignant transformation.

Related: SIL gene

Zhou Y, Kurukuti S, Saffrey P, et al.
Chromatin looping defines expression of TAL1, its flanking genes, and regulation in T-ALL.
Blood. 2013; 122(26):4199-209 [PubMed] Related Publications
TAL1 is an important regulator of hematopoiesis and its expression is tightly controlled despite complexities in its genomic organization. It is frequently misregulated in T-cell acute lymphoblastic leukemia (T-ALL), often due to deletions between TAL1 and the neighboring STIL gene. To better understand the events that lead to TAL1 expression in hematopoiesis and in T-ALL, we studied looping interactions at the TAL1 locus. In TAL1-expressing erythroid cells, the locus adopts a looping "hub" which brings into close physical proximity all known TAL1 cis-regulatory elements including CTCF-bound insulators. Loss of GATA1 results in disassembly of the hub and loss of CTCF/RAD21 from one of its insulators. Genes flanking TAL1 are partly dependent on hub integrity for their transcriptional regulation. We identified looping patterns unique to TAL1-expressing T-ALL cells, and, intriguingly, loops occurring between the TAL1 and STIL genes at the common TAL1/STIL breakpoints found in T-ALL. These findings redefine how TAL1 and neighboring genes communicate within the nucleus, and indicate that looping facilitates both normal and aberrant TAL1 expression and may predispose to structural rearrangements in T-ALL. We also propose that GATA1-dependent looping mechanisms may facilitate the conservation of TAL1 regulation despite cis-regulatory remodeling during vertebrate evolution.

Related: GATA1 gene SIL gene

Meissner B, Bartram T, Eckert C, et al.
Frequent and sex-biased deletion of SLX4IP by illegitimate V(D)J-mediated recombination in childhood acute lymphoblastic leukemia.
Hum Mol Genet. 2014; 23(3):590-601 [PubMed] Related Publications
Acute lymphoblastic leukemia (ALL) accounts for ∼25% of pediatric malignancies. Of interest, the incidence of ALL is observed ∼20% higher in males relative to females. The mechanism behind the phenomenon of sex-specific differences is presently not understood. Employing genome-wide genetic aberration screening in 19 ALL samples, one of the most recurrent lesions identified was monoallelic deletion of the 5' region of SLX4IP. We characterized this deletion by conventional molecular genetic techniques and analyzed its interrelationships with biological and clinical characteristics using specimens and data from 993 pediatric patients enrolled into trial AIEOP-BFM ALL 2000. Deletion of SLX4IP was detected in ∼30% of patients. Breakpoints within SLX4IP were defined to recurrent positions and revealed junctions with typical characteristics of illegitimate V(D)J-mediated recombination. In initial and validation analyses, SLX4IP deletions were significantly associated with male gender and ETV6/RUNX1-rearranged ALL (both overall P < 0.0001). For mechanistic validation, a second recurrent deletion affecting TAL1 and caused by the same molecular mechanism was analyzed in 1149 T-cell ALL patients. Validating a differential role by sex of illegitimate V(D)J-mediated recombination at the TAL1 locus, 128 out of 1149 T-cell ALL samples bore a deletion and males were significantly more often affected (P = 0.002). The repeatedly detected association of SLX4IP deletion with male sex and the extension of the sex bias to deletion of the TAL1 locus suggest that differential illegitimate V(D)J-mediated recombination events at specific loci may contribute to the consistent observation of higher incidence rates of childhood ALL in boys compared with girls.

Related: Acute Lymphocytic Leukemia (ALL) Childhood Acute lymphoblastic leukaemia (ALL) ALL - Molecular Biology ETV6 (TEL) gene RUNX1 gene

Mandoli A, Singh AA, Jansen PW, et al.
CBFB-MYH11/RUNX1 together with a compendium of hematopoietic regulators, chromatin modifiers and basal transcription factors occupies self-renewal genes in inv(16) acute myeloid leukemia.
Leukemia. 2014; 28(4):770-8 [PubMed] Related Publications
Different mechanisms for CBFβ-MYH11 function in acute myeloid leukemia with inv(16) have been proposed such as tethering of RUNX1 outside the nucleus, interference with transcription factor complex assembly and recruitment of histone deacetylases, all resulting in transcriptional repression of RUNX1 target genes. Here, through genome-wide CBFβ-MYH11-binding site analysis and quantitative interaction proteomics, we found that CBFβ-MYH11 localizes to RUNX1 occupied promoters, where it interacts with TAL1, FLI1 and TBP-associated factors (TAFs) in the context of the hematopoietic transcription factors ERG, GATA2 and PU.1/SPI1 and the coregulators EP300 and HDAC1. Transcriptional analysis revealed that upon fusion protein knockdown, a small subset of the CBFβ-MYH11 target genes show increased expression, confirming a role in transcriptional repression. However, the majority of CBFβ-MYH11 target genes, including genes implicated in hematopoietic stem cell self-renewal such as ID1, LMO1 and JAG1, are actively transcribed and repressed upon fusion protein knockdown. Together these results suggest an essential role for CBFβ-MYH11 in regulating the expression of genes involved in maintaining a stem cell phenotype.

Related: Chromosome 16 GATA2 gene Acute Myeloid Leukemia (AML) FLI1 gene RUNX1 gene

Wang SL, Wang FF, Chen SL, et al.
Expression, localization and clinical application of exogenous Smith proteins D1 in gene transfected HEp-2 cells.
Int J Rheum Dis. 2013; 16(3):303-9 [PubMed] Related Publications
AIM: To establish an improved substrate for an indirect immunofluorescence test (IIF) to detect anti-Sm antibody.
METHODS: Full-length Smith protein D1(Sm-D1) complementary DNA was obtained from human larynx carcinoma cell line HEp-2 by reverse transcription - polymerase chain reaction (RT-PCR) and cloned into the mammalian expression vector pEGFP-C1. The recombinant plasmid pEGFP-Sm-D1 was transfected into HEp-2 cells. The expression, localization and antigenicity of fusion proteins of green fluorescent protein (GFP) in transfected cells were confirmed by means of immunoblotting (IBT), confocal fluorescence microscopy and IIF analysis. Transfected HEp-2 cells were analyzed with reference serum and compared with untransfected HEp-2 cells by IIF.
RESULTS: Stable expression of the Sm-D1-GFP was maintained for more than ten generations. This Sm-D1-GFP showed the antigenicity of Sm-D1 with a characteristic phenotype in IIF.Six of 12 serum specimens from systemic lupus erythematosus contained both 29/28 and 13.5 kDa proteins and showed characteristic immunofluorescent patterns. The same phenomenon appeared in 3/6 serum samples which contained 29/28 kDa proteins only. Sera from 10 healthy donors did not react with HEp-Sm-D1 or HEp-2 at 1:80 attenuant degrees. No alteration in expression, localization and morphology was observed when HEp-Sm-D1 or HEp-2 interacted with the reference sera which could react with Ro/SSA, La/SSB, β2GP1, centromere, histone, and Scl-70 antibodies in routine IIF tests.
CONCLUSION: As a new kind of substrate of IIF, HEp-Sm-D1 can be used to detect anti-Sm antibodies. Transfected HEp-2 cells keep the immunofluorescent property of HEp-2 cells in immunofluorescence anti-nuclear antibody (IFANA) test and could potentially be used as substrate for routine IFANA detection.

Related: Cancer of the Larynx Laryngeal Cancer - Molecular Biology

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.

Wang W, Li NN, Du Y, et al.
FoxO3a and nilotinib-induced erythroid differentiation of CML-BC cells.
Leuk Res. 2013; 37(10):1309-14 [PubMed] Related Publications
We explored the potential involvement of FoxO3a activation in erythroid and granulocytic differentiation for Ph(+) cells of chronic myeloid leukemia blast crisis (CML BC). We demonstrate that FoxO3a activation in CML blast crisis (BC) cells by overexpressing FoxO3a leads to the maturation of CML BC cells. Hemoglobin production significantly increased upon FoxO3a activation in CML BC cells. FoxO3a activation upregulated erythroid surface protein (glycophorin A, GPA), but did not significantly modulate granulocytic markers (CD11b). Additionally, FoxO3a activation reduced the mRNA and protein expression of Tal1. Similar results were observed in cells that were given nilotinib. Our results indicate that FoxO3a activation may promote erythroid differentiation of BC cells via down-regulating Tal1 expression.

Related: Chronic Myeloid Leukemia (CML) CML - Molecular Biology

Larmonie NS, Dik WA, Meijerink JP, et al.
Breakpoint sites disclose the role of the V(D)J recombination machinery in the formation of T-cell receptor (TCR) and non-TCR associated aberrations in T-cell acute lymphoblastic leukemia.
Haematologica. 2013; 98(8):1173-84 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
Aberrant recombination between T-cell receptor genes and oncogenes gives rise to chromosomal translocations that are genetic hallmarks in several subsets of human T-cell acute lymphoblastic leukemias. The V(D)J recombination machinery has been shown to play a role in the formation of these T-cell receptor translocations. Other, non-T-cell receptor chromosomal aberrations, such as SIL-TAL1 deletions, have likewise been recognized as V(D)J recombination associated aberrations. Despite the postulated role of V(D)J recombination, the extent of the V(D)J recombination machinery involvement in the formation of T-cell receptor and non-T-cell receptor aberrations in T-cell acute lymphoblastic leukemia is still poorly understood. We performed a comprehensive in silico and ex vivo evaluation of 117 breakpoint sites from 22 different T-cell receptor translocation partners as well as 118 breakpoint sites from non-T-cell receptor chromosomal aberrations. Based on this extensive set of breakpoint data, we provide a comprehensive overview of T-cell receptor and oncogene involvement in T-ALL. Moreover, we assessed the role of the V(D)J recombination machinery in the formation of chromosomal aberrations, and propose an up-dated mechanistic classification on how the V(D)J recombination machinery contributes to the formation of T-cell receptor and non-T-cell receptor aberrations in human T-cell acute lymphoblastic leukemia.

Mansour MR, Sanda T, Lawton LN, et al.
The TAL1 complex targets the FBXW7 tumor suppressor by activating miR-223 in human T cell acute lymphoblastic leukemia.
J Exp Med. 2013; 210(8):1545-57 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
The oncogenic transcription factor TAL1/SCL is aberrantly expressed in 60% of cases of human T cell acute lymphoblastic leukemia (T-ALL) and initiates T-ALL in mouse models. By performing global microRNA (miRNA) expression profiling after depletion of TAL1, together with genome-wide analysis of TAL1 occupancy by chromatin immunoprecipitation coupled to massively parallel DNA sequencing, we identified the miRNA genes directly controlled by TAL1 and its regulatory partners HEB, E2A, LMO1/2, GATA3, and RUNX1. The most dynamically regulated miRNA was miR-223, which is bound at its promoter and up-regulated by the TAL1 complex. miR-223 expression mirrors TAL1 levels during thymic development, with high expression in early thymocytes and marked down-regulation after the double-negative-2 stage of maturation. We demonstrate that aberrant miR-223 up-regulation by TAL1 is important for optimal growth of TAL1-positive T-ALL cells and that sustained expression of miR-223 partially rescues T-ALL cells after TAL1 knockdown. Overexpression of miR-223 also leads to marked down-regulation of FBXW7 protein expression, whereas knockdown of TAL1 leads to up-regulation of FBXW7 protein levels, with a marked reduction of its substrates MYC, MYB, NOTCH1, and CYCLIN E. We conclude that TAL1-mediated up-regulation of miR-223 promotes the malignant phenotype in T-ALL through repression of the FBXW7 tumor suppressor.

Related: Apoptosis FBXW7 gene

Tsunoda T, Shirasawa S
Roles of ZFAT in haematopoiesis, angiogenesis and cancer development.
Anticancer Res. 2013; 33(7):2833-7 [PubMed] Related Publications
A zinc-finger gene in autoimmune thyroid disease susceptibility region (ZFAT) was originally identified as a highly conserved immune-related transcriptional regulator containing one adenosine-thymidine (AT)-hook and 18 C2H2-type zinc-finger domains. Subsequently, roles of ZFAT in development, primitive haematopoiesis, angiogenesis, immune responses and several common diseases, such as multiple sclerosis, hypertension and cancer, have been demonstrated. Previously, we recorded a ZFAT protein expression in MOLT-4 human acute T-lymphoblastic leukaemia cells, while ZFAT knockdown activated caspases and induced apoptosis in these cells. Hence, the precise functions of ZFAT are of particular interest in cancer research. In this article, we have reviewed investigations on the roles of ZFAT in haematopoietic and angiogenesis, and discussed the possible involvement of ZFAT in haematopoietic malignancies.

Related: Haematological Malignancies & Realted Disorders Angiogenesis and Cancer

Patel B, Kang Y, Cui K, et al.
Aberrant TAL1 activation is mediated by an interchromosomal interaction in human T-cell acute lymphoblastic leukemia.
Leukemia. 2014; 28(2):349-61 [PubMed] Related Publications
Long-range chromatin interactions control metazoan gene transcription. However, the involvement of intra- and interchromosomal interactions in development and oncogenesis remains unclear. TAL1/SCL is a critical transcription factor required for the development of all hematopoietic lineages; yet, aberrant TAL1 transcription often occurs in T-cell acute lymphoblastic leukemia (T-ALL). Here, we report that oncogenic TAL1 expression is regulated by different intra- and interchromosomal loops in normal hematopoietic and leukemic cells, respectively. These intra- and interchromosomal loops alter the cell-type-specific enhancers that interact with the TAL1 promoter. We show that human SET1 (hSET1)-mediated H3K4 methylations promote a long-range chromatin loop, which brings the +51 enhancer in close proximity to TAL1 promoter 1 in erythroid cells. The CCCTC-binding factor (CTCF) facilitates this long-range enhancer/promoter interaction of the TAL1 locus in erythroid cells while blocking the same enhancer/promoter interaction of the TAL1 locus in human T-cell leukemia. In human T-ALL, a T-cell-specific transcription factor c-Maf-mediated interchromosomal interaction brings the TAL1 promoter into close proximity with a T-cell-specific regulatory element located on chromosome 16, activating aberrant TAL1 oncogene expression. Thus, our study reveals a novel molecular mechanism involving changes in three-dimensional chromatin interactions that activate the TAL1 oncogene in human T-cell leukemia.

Related: Chromosome 16

Xin L, Cao J, Cheng H, et al.
Stealth cationic liposomes modified with anti-CAGE single-chain fragment variable deliver recombinant methioninase for gastric carcinoma therapy.
J Nanosci Nanotechnol. 2013; 13(1):178-83 [PubMed] Related Publications
Stealth cationic liposomes (SCLs) modified with tumor-targeting single-chain fragment variable (scFV) antibody for systemic delivery of recombinant methioninase (rMETase) for gastric cancer were prepared successfully. These functional SCL nanoparticles are composed of cationic lipids, dioleoylphosphatidylethanolamine, and distearoylphosphatidylethanolamine-polyethylene glycol, which have lower gene transfection efficiencies compared with Lipofectamine 2000, and can also be used as effective gene delivery vectors. Increased therapeutic efficiency of rMETase-loaded scFV-SCLs were tested in SGC-7901 cells and compared with free rMETase in solution and rMETase-loaded SCLs. In addition, scFV-SCLs (effective diameter: 185.7 nm; polydispersity index: 0.236) can significantly boost rhodamine 123 cellular accumulation in the cytoplasm. The scFV-targeted SCLs can be used as a potentially effective drug delivery system.

Related: Stomach Cancer Gastric Cancer

Senzer N, Nemunaitis J, Nemunaitis D, et al.
Phase I study of a systemically delivered p53 nanoparticle in advanced solid tumors.
Mol Ther. 2013; 21(5):1096-103 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
Selective delivery of therapeutic molecules to primary and metastatic tumors is optimal for effective cancer therapy. A liposomal nanodelivery complex (scL) for systemic, tumor-targeting delivery of anticancer therapeutics has been developed. scL employs an anti-transferrin receptor (TfR), scFv as the targeting molecule. Loss of p53 suppressor function, through mutations or inactivation of the p53 pathway, is present in most human cancers. Rather than being transiently permissive for tumor initiation, persistence of p53 dysfunction is a continuing requirement for maintaining tumor growth. Herein, we report results of a first-in-man Phase I clinical trial of restoration of the normal human tumor suppressor gene p53 using the scL nanocomplex (SGT-53). Minimal side effects were observed in this trial in patients with advanced solid tumors. Furthermore, the majority of patients demonstrated stable disease. One patient with adenoid cystic carcinoma had his status changed from unresectable to resectable after one treatment cycle. More significantly, we observed an accumulation of the transgene in metastatic tumors, but not in normal skin tissue, in a dose-related manner. These results show not only that systemically delivered SGT-53 is well tolerated and exhibits anticancer activity, but also supply evidence of targeted tumor delivery of SGT-53 to metastatic lesions.

Related: Cancer Prevention and Risk Reduction

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 01/01/2015 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.

Related: Acute Myeloid Leukemia (AML)

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.

Related: GATA2 gene Acute Myeloid Leukemia (AML) FLI1 gene ERG gene LMO2 gene RUNX1 gene

Awan T, Iqbal Z, Aleem A, et al.
Five most common prognostically important fusion oncogenes are detected in the majority of Pakistani pediatric acute lymphoblastic leukemia patients and are strongly associated with disease biology and treatment outcome.
Asian Pac J Cancer Prev. 2012; 13(11):5469-75 [PubMed] Related Publications
BACKGROUND AND OBJECTIVES: Acute lymphoblastic leukemia (ALL) is a complex genetic disease involving many fusion oncogenes (FO) having prognostic significance. The frequency of various FO can vary in different ethnic groups, with important implications for prognosis, drug selection and treatment outcome.
METHOD: We studied fusion oncogenes in 101 pediatric ALL patients using interphase FISH and RT-PCR, and their associations with clinical features and treatment outcome.
RESULTS: Five most common fusion genes i.e. BCR-ABL t (22; 9), TCF3-PBX1 (t 1; 19), ETV6-RUNX1 (t 12; 21), MLL-AF4 (t 4; 11) and SIL-TAL1 (del 1p32) were found in 89/101 (88.1%) patients. Frequency of BCR-ABL was 44.5% (45/101). BCR-ABL positive patients had a significantly lower survival (43.7±4.24 weeks) and higher white cell count as compared to others, except patients with MLL-AF4. The highest relapse-free survival was documented with ETV6-RUNX1 (14.2 months) followed closely by those cases in which no gene was detected (13.100). RFS with BCR-ABL, MLL-AF4, TCF3-PBX1 and SIL-TAL1 was less than 10 months (8.0, 3.6, 5.5 and 8.1 months, respectively).
CONCLUSIONS: This is the first study from Pakistan correlating molecular markers with disease biology and treatment outcome in pediatric ALL. It revealed the highest reported frequency of BCR-ABL FO in pediatric ALL, associated with poor overall survival. Our data indicate an immediate need for incorporation of tyrosine kinase inhibitors in the treatment of BCR-ABL+ pediatric ALL in this population and the development of facilities for stem cell transplantation.

Related: Acute Lymphocytic Leukemia (ALL) Childhood Acute lymphoblastic leukaemia (ALL) ALL - Molecular Biology

Oram SH, Thoms J, Sive JI, et al.
Bivalent promoter marks and a latent enhancer may prime the leukaemia oncogene LMO1 for ectopic expression in T-cell leukaemia.
Leukemia. 2013; 27(6):1348-57 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
LMO1 is a transcriptional regulator and a T-acute lymphoblastic leukaemia (T-ALL) oncogene. Although first identified in association with a chromosomal translocation in T-ALL, the ectopic expression of LMO1 occurs far more frequently in the absence of any known mutation involving its locus. Given that LMO1 is barely expressed in any haematopoietic lineage, and activation of transcriptional drivers in leukaemic cells is not well described, we investigated the regulation of this gene in normal haematopoietic and leukaemic cells. We show that LMO1 has two promoters that drive reporter gene expression in transgenic mice to neural tissues known to express endogenous LMO1. The LMO1 promoters display bivalent histone marks in multiple blood lineages including T-cells, and a 3' flanking region at LMO1 +57 contains a transcriptional enhancer that is active in developing blood cells in transgenic mouse embryos. The LMO1 promoters become activated in T-ALL together with the 3' enhancer, which is bound in primary T-ALL cells by SCL/TAL1 and GATA3. Taken together, our results show that LMO1 is poised for expression in normal progenitors, where activation of SCL/TAL1 together with a breakdown of epigenetic repression of LMO1 regulatory elements induces ectopic LMO1 expression that contributes to the development and maintenance of T-ALL.

Related: LMO1

Yin HX, Zhang ZH, Shen JC, et al.
Scl gene construction, expression and effect on hemangioma.
Mol Biol Rep. 2013; 40(4):3381-8 [PubMed] Related Publications
Hemangioma is a tumor that causes vascular endothelial cell hyperplasia, which commonly occur in newborns. Angiogenesis inhibitor targets the processes of angiogenesis, including the proliferation of vascular endothelial cells. A DNA sequence named Scl was designed, recombined into Pichia Pastoris, expressed by fermenting the engineered strain in a bioreactor, and purified the recombinant Scl by SP-sepharose fast flow. Scl can inhibit CAM angiogenesis. Only 1 μg of Scl significantly suppressed the growth of CAM blood vessel, similar to that of 25 μg of angiostatin. Scl showed a strong cytotoxicity on hemangioma cell (ATCC CRL No. 2587). After the drug acted for 24 h, the OD 570 measured value of the PBS control group averaged 1.873, whereas that of the Sc1 drug group was 0.692 (P < 0.01). Using the DeadEndTM Fluorometric TUNEL System, the detection results showed that 92 % of hemangioma cell apoptosis was observed in the Scl protein group, but only 1.3 % in the PBS control group (P < 0.01). After 2 weeks of treatment with the hemangioma model (cock's wattle) of the PBS group, 151 blood vessels with 100 views (40×) were obtained, whereas 250 in the PBS group (P < 0.01). During the two-week medication, the hemangioma model of the PBS group increased by 1.18 cm, whereas only 0.58 cm in the Scl drug group (P < 0.01).

Related: Angiogenesis Inhibitors Apoptosis Angiogenesis and Cancer

Liu F, Gao L, Jing Y, et al.
Detection and clinical significance of gene rearrangements in Chinese patients with adult acute lymphoblastic leukemia.
Leuk Lymphoma. 2013; 54(7):1521-6 [PubMed] Related Publications
This study aimed to develop a novel multiplex reverse transcription-nested polymerase chain reaction (RT-nPCR) assay to accurately and effectively detect 10 common gene rearrangements in adult acute lymphoblastic leukemia (ALL) and to examine the clinicopathologic characteristics and other genetic aberrations of patients with ALL expressing different fusion genes. Our RT-nPCR assay had a positive detection rate of 35.15% (90/256) for the 10 fusion genes. BCR-ABL1, FUS-ERG, MLL-AF4, ETV6-RUNX1, E2A-PBX1, dupMLL, MLL-AF10, MLL-ENL, SET-NUP214 and SIL-TAL1 were detected in 36 (14.06%), 14 (5.47%), 14 (5.47%), four (1.56%), four (1.56%), five (1.95%), four (1.56%), two (0.78%), two (0.78%) and five patients (1.95%), respectively. The RT-nPCR results were further confirmed by split-out PCR, and cytogenetic and fluorescence in situ hybridization (FISH) analysis revealed corresponding translocations and fusions in 63 and 74 cases, respectively. JAK2 and IKZF1 mutations were commonly detected in patients with BCR-ABL1 ALL, and HOX overexpression was highly correlated with MLL fusions and SET-NUP214. This study demonstrates that RT-nPCR is an effective method for identifying 10 gene rearrangements in adult ALL, and it could potentially be developed for diagnostic use and prognostic studies of ALL.

Related: Acute Lymphocytic Leukemia (ALL)

Ziebarth JD, Bhattacharya A, Cui Y
Integrative analysis of somatic mutations altering microRNA targeting in cancer genomes.
PLoS One. 2012; 7(10):e47137 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
Determining the functional impact of somatic mutations is crucial to understanding tumorigenesis and metastasis. Recent sequences of several cancers have provided comprehensive lists of somatic mutations across entire genomes, enabling investigation of the functional impact of somatic mutations in non-coding regions. Here, we study somatic mutations in 3'UTRs of genes that have been identified in four cancers and computationally predict how they may alter miRNA targeting, potentially resulting in dysregulation of the expression of the genes harboring these mutations. We find that somatic mutations create or disrupt putative miRNA target sites in the 3'UTRs of many genes, including several genes, such as MITF, EPHA3, TAL1, SCG3, and GSDMA, which have been previously associated with cancer. We also integrate the somatic mutations with germline mutations and results of association studies. Specifically, we identify putative miRNA target sites in the 3'UTRs of BMPR1B, KLK3, and SPRY4 that are disrupted by both somatic and germline mutations and, also, are in linkage disequilibrium blocks with high scoring markers from cancer association studies. The somatic mutation in BMPR1B is located in a target site of miR-125b; germline mutations in this target site have previously been both shown to disrupt regulation of BMPR1B by miR-125b and linked with cancer.

Related: Cancer Prevention and Risk Reduction

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.

Related: Leukemia CREB1 gene

Sabir N, Iqbal Z, Aleem A, et al.
Prognostically significant fusion oncogenes in Pakistani patients with adult acute lymphoblastic leukemia and their association with disease biology and outcome.
Asian Pac J Cancer Prev. 2012; 13(7):3349-55 [PubMed] Related Publications
BACKGROUND AND OBJECTIVES: Chromosomal abnormalities play an important role in genesis of acute lymphoblastic leukemia (ALL) and have prognostic implications. Five major risk stratifying fusion genes in ALL are BCR-ABL, MLL-AF4, ETV6-RUNX11, E2A-PBX1 and SIL-TAL1. This work aimed to detect common chromosomal translocations and associated fusion oncogenes in adult ALL patients and study their relationship with clinical features and treatment outcome.
METHODS: We studied fusion oncogenes in 104 adult ALL patients using RT-PCR and interphase-FISH at diagnosis and their association with clinical characteristics and treatment outcome.
RESULTS: Five most common fusion genes i.e. BCR-ABL (t 9; 22), TCF3-PBX1 (t 1; 19), ETV6-RUNX1 (t 12; 21), MLL-AF4 (t 4; 11) and SIL-TAL1 (Del 1p32) were found in 82/104 (79%) patients. TCF3-PBX1 fusion gene was associated with lymphadenopathy, SIL-TAL positive patients had frequent organomegaly and usually presented with a platelets count of less than 50 x10(9)/l. Survival of patients with fusion gene ETV6-RUNX1 was better when compared to patients harboring other genes. MLL-AF4 and BCR-ABL positivity characterized a subset of adult ALL patients with aggressive clinical behaviour and a poor outcome.
CONCLUSIONS: This is the first study from Pakistan which investigated the frequency of 5 fusion oncogenes in adult ALL patients, and their association with clinical features, treatment response and outcome. Frequencies of some of the oncogenes were different from those reported elsewhere and they appear to be associated with distinct clinical characteristics and treatment outcome. This information will help in the prognostic stratification and risk adapted management of adult ALL patients.

Related: Acute Lymphocytic Leukemia (ALL)

Sanda T, Lawton LN, Barrasa MI, et al.
Core transcriptional regulatory circuit controlled by the TAL1 complex in human T cell acute lymphoblastic leukemia.
Cancer Cell. 2012; 22(2):209-21 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
The oncogenic transcription factor TAL1/SCL is aberrantly expressed in over 40% of cases of human T cell acute lymphoblastic leukemia (T-ALL), emphasizing its importance in the molecular pathogenesis of T-ALL. Here we identify the core transcriptional regulatory circuit controlled by TAL1 and its regulatory partners HEB, E2A, LMO1/2, GATA3, and RUNX1. We show that TAL1 forms a positive interconnected autoregulatory loop with GATA3 and RUNX1 and that the TAL1 complex directly activates the MYB oncogene, forming a positive feed-forward regulatory loop that reinforces and stabilizes the TAL1-regulated oncogenic program. One of the critical downstream targets in this circuitry is the TRIB2 gene, which is oppositely regulated by TAL1 and E2A/HEB and is essential for the survival of T-ALL cells.

Meng X, Lu P, Bai H, et al.
Transcriptional regulatory networks in human lung adenocarcinoma.
Mol Med Rep. 2012; 6(5):961-6 [PubMed] Related Publications
Lung adenocarcinoma (AC) is the most common histological subtype of lung cancer worldwide and its absolute incidence is increasing markedly. Transcriptional regulation is one of the most fundamental processes in lung AC development. However, high-throughput functional analyses of multiple transcription factors and their target genes in lung AC are rare. Thus, the objective of our study was to interpret the mechanisms of human AC through the regulatory network using the GSE2514 microarray data. Our results identified the genes peroxisome proliferator activated receptor-γ (PPARG), CCAAT/enhancer binding protein β (CEBPB), ets variant 4 (ETV4), Friend leukemia virus integration 1 (FLI1), T-cell acute lymphocytic leukemia 1 (TAL1) and nuclear factor of kappa light polypeptide gene enhancer in B-cells 1 (NFKB1) as hub nodes in the transcriptome network. Among these genes, it appears that: PPARG promotes the PPAR signaling pathway via the upregulation of lipoprotein lipase (LPL) expression, but suppresses the cell cycle pathway via downregulation of growth arrest and DNA-damage-inducible, γ (GADD45G) expression; ETV4 stimulates matrix metallopeptidase 9 (MMP9) expression to induce the bladder cancer pathway; FLI upregulates transforming growth factor, β receptor II (TGFBR2) expression to activate TGF-β signaling and upregulates cyclin D3 (CCND3) expression to promote the cell cycle pathway; NFKB1 upregulates interleukin 1, β (IL-1B) expression and initiates the prostate cancer pathway; CEBPB upregulates IL-6 expression and promotes pathways in cancer; and TAL1 promotes kinase insert domain receptor (KDR) expression to promote the TGF-β signaling pathway. This transcriptional regulation analysis may provide an improved understanding of the molecular mechanisms and potential therapeutic targets in the treatment of lung AC.

Related: Lung Cancer MMP9: matrix metallopeptidase 9 PPARG gene FLI1 gene Signal Transduction ETV4 gene TGFBR2

Nagel S, Ehrentraut S, Tomasch J, et al.
Transcriptional activation of prostate specific homeobox gene NKX3-1 in subsets of T-cell lymphoblastic leukemia (T-ALL).
PLoS One. 2012; 7(7):e40747 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
Homeobox genes encode transcription factors impacting key developmental processes including embryogenesis, organogenesis, and cell differentiation. Reflecting their tight transcriptional control, homeobox genes are often embedded in large non-coding, cis-regulatory regions, containing tissue specific elements. In T-cell acute lymphoblastic leukemia (T-ALL) homeobox genes are frequently deregulated by chromosomal aberrations, notably translocations adding T-cell specific activatory elements. NKX3-1 is a prostate specific homeobox gene activated in T-ALL patients expressing oncogenic TAL1 or displaying immature T-cell characteristics. After investigating regulation of NKX3-1 in primary cells and cell lines, we report its ectopic expression in T-ALL cells independent of chromosomal rearrangements. Using siRNAs and expression profiling, we exploited NKX3-1 positive T-ALL cell lines as tools to investigate aberrant activatory mechanisms. Our data confirmed NKX3-1 activation by TAL1/GATA3/LMO and identified LYL1 as an alternative activator in immature T-ALL cells devoid of GATA3. Moreover, we showed that NKX3-1 is directly activated by early T-cell homeodomain factor MSX2. These activators were regulated by MLL and/or by IL7-, BMP4- and IGF2-signalling. Finally, we demonstrated homeobox gene SIX6 as a direct leukemic target of NKX3-1 in T-ALL. In conclusion, we identified three major mechanisms of NKX3-1 regulation in T-ALL cell lines which are represented by activators TAL1, LYL1 and MSX2, corresponding to particular T-ALL subtypes described in patients. These results may contribute to the understanding of leukemic transcriptional networks underlying disturbed T-cell differentiation in T-ALL.


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