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Results for “ETS Translocation Variant 6 Protein”

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At least 433 records · Page 24Linked to original sources
PubMed2006

Resolution of ambiguous low-level positive quantitative polymerase chain reaction results in TEL-AML1 positive ALL using a post-PCR fluorescent oligoligation method.

The interpretation of low-level or non-reproducible amplification results in clinical quantitative polymerase chain reaction (Q-PCR) assays can be difficult to definitively resolve. Concerning minimal residual disease detection in leukaemia, indeterminate low-level results might create prognostic or therapeutic dilemmas. We evaluated low-level, ambiguous Q-PCR results in a study of paired diagnostic and end-induction (day 29) TEL-AML1 positive acute lymphoblastic leukaemia samples utilising a novel fluorescent primer ligation detection assay. The data presented here indicate that a significant number of low-level apparent Q-PCR positive results may be spurious or non-specific in nature, requiring additional technical manoeuvres for confirmation of true positive cases.

Child↗
PubMed2003

Absence of leukaemic fusion gene transcripts in preterm infants exposed to diagnostic x rays.

BACKGROUND: Childhood leukaemias express novel, clonotypic fusion genes that may already be present at birth before the clinical manifestation of leukaemia. Exposure of the fetus to diagnostic x rays is reported to increase the risk of childhood leukaemia, and may do so by generating leukaemic fusion genes. Advances in neonatal medicine in the past decade that have extended the limits of viability of preterm babies down to 23 weeks of gestation have resulted in the increased use of diagnostic x rays to monitor neonatal progress. AIM: To investigate whether exposure of very preterm infants to diagnostic x rays in the neonatal period leads to the development of leukaemic fusion genes. METHODS: Peripheral blood samples were collected at birth from very preterm infants (23-30 weeks gestation) and following exposure to diagnostic x rays at intervals of two weeks, until discharge. Cord blood samples from normal full term infants served as controls. Total RNA was extracted from the blood and the expression of the fusion genes TEL-AML1, MLL-AF4, and BCR-ABL, characteristic of three subtypes of childhood leukaemia, was investigated in the preterm and full term infant samples using a nested reverse transcriptase polymerase chain reaction method. Serial pre- and post-x ray samples from 42 preterm babies, pre-x ray samples from an additional 46 preterm infants, and cord blood samples from 100 normal full term infants were screened for fusion gene transcripts. RESULTS: No leukaemic fusion gene transcripts were detected in preterm infants following exposure to diagnostic x rays. A BCR-ABL transcript was identified in a single preterm infant prior to x ray exposure. TEL-AML1 transcripts were detected in cord blood samples from two full term infants. MLL-AF4 transcripts were not detected in any of the pre- or full term infants tested. CONCLUSIONS: Exposure of the preterm infants to x rays in this small series and at the doses used for diagnostic purposes did not induce leukaemic fusion gene expression, but we cannot exclude the possibility that a small proportion of preterm infants may be unusually sensitive to x rays.

Cell Line↗
PubMed2004

Transforming property of TEL-FGFR3 mediated through PI3-K in a T-cell lymphoma that subsequently progressed to AML.

We previously reported a novel fusion between TEL and FGFR3 in a patient with peripheral T-cell lymphoma with t(4; 12)(p16;p13). Disease in this patient subsequently progressed to acute myelogenous leukemia (AML) with the same translocation. Sequence analysis of TEL-FGFR3 fusion transcripts suggested that these diseases originated from the same multipotent stem cell. To determine the transforming property of TEL-FGFR3, we established transfectants of this chimeric fusion gene and investigated the major signal pathways of TEL-FGFR3-induced transformation using various signal transduction inhibitors including SU5402 (fibroblast growth factor tyrosine kinase [FGFR TK] inhibitor). Our results indicated that (1) the expression of TEL-FGFR3 but not DeltaHLH-TEL-FGFR3 resulted in efficient focus formation in NIH/3T3 cells and conferred interleukin 3 independence to Ba/F3 cells by a constitutive tyrosine kinase activity probably through oligomerization by the HLH domain of TEL; (2) although effector proteins including classical mitogen-activated protein kinase (MAPK), p38 MAPK, phosphatidylinositol 3-kinase (PI3-K), mammalian target or rapamycin (mTOR), signal transducer and activator of transcription 3 (STAT-3) and STAT-5 were activated in TEL-FGFR3 transformants, the growth of the transformants was inhibited by SU5402 (concentration that inhibits 50% [IC5)]=5 microM) and the PI3-K inhibitor, LY294002 (IC5)=10 microM) and wortmannin (IC50=5 microM), but not by U0126, SB203580, or rapamycin; and (3) injection of TEL-FGFR3 transformants induced lethal leukemia into syngeneic mice. Taken together, the leukemogenic potential of TEL-FGFR3 may be mediated in part through PI3-K.

Acute Disease↗
PubMed2001

Chemosensitivity of TEL-AML1 fusion transcript positive acute lymphoblastic leukemia cells.

The TEL-AML1 fusion which results from a cryptic t(12;21) translocation is the most frequently occurring genetic abnormality in childhood acute lymphoblastic leukemia (ALL) and has been associated with an excellent treatment outcome. In the present study, we examined the FAS/BCL-2 expression profiles and chemosensitivity of primary leukemic cells from children with newly diagnosed t(12;21)TEL-AML1 fusion transcript-positive versus t(12;21)TEL-AML1 fusion transcript-negative standard risk ALL. TEL-AML1(+) ALL cells expressed higher levels of the pro-apoptotic protein Fas and lower levels of the anti-apoptotic protein Bcl2 than TEL-AML1(-) ALL cells, as determined by confocal laser scanning microscopy. TEL-AML1(+) ALL cells were more sensitive to the apoptosis-inducing effects of serum deprivation, dexamethasone and vincristine than TEL-AML1(-) ALL cells. This study provides novel mechanistic insights regarding the chemosensitivity of TEL-AML1(+) ALL cells and provides a cogent explanation for the excellent leukemia-free survival outcome of children with TEL-AML1(+) ALL treated on contemporary chemotherapy programs.

Apoptosis↗
PubMed1999

Functional characterization of TEL/AML1 fusion protein in the regulation of human CR1 gene promoter.

The TEL/AML1 fusion gene occurs in childhood B-cell acute lymphoblastic leukemia (ALL) as a result of the translocation of human chromosome 12;21. Using reporter gene assays, we have functionally characterized TEL, AML1 and TEL/AML1 fusion proteins in the regulation of the human CR1 gene. Analysis of transcription activities showed that AML1 increased the CR1 promoter activity and that TEL repressed the basal activity of the promoter. Increased activities of the CR1 promoter by AML1 protein were reduced by the TEL protein in a concentration-dependent manner. When TEL/AML1 and AML1 proteins are present in cells at the same time, the TEL/AML1 protein inhibits the transactivation activities of AML1 protein on the human CR1 promoter even though TEL/AML1 retains the transactivation domain of AML1. A mutation analysis of the human CR1 promoter revealed that the binding sites for TEL and AML1 are necessary for the action of TEL and TEL/AML1, respectively. Thus, production of the TEL/AML1 protein by translocation of human chromosome 12;21 may contribute to leukemogenesis by the specific inhibition of AML1-dependent activation of myeloid promoters.

Binding Sites↗
PubMed1999

[Detection of BCR/ABL, MLL/AF4 and TEL/AML1 hybrid genes and monitoring of minimal residual disease in pediatric patients with acute lymphoblastic leukemia].

BACKGROUND: The BCR/ABL and MLL/AF4 fusion genes--resulting from t(9;22)(q34;q11) and t(4;11)(q21;q23) translocations, respectively--are considered as a high risk prognostic factors in children with acute lymphoblastic leukaemia (ALL). Their presence in malignant cells indicates patient for the most intensive antileukaemic therapy regardless of the other criteria. In contrast, the most common non-random chromosomal aberration in paediatric ALL--translocation t(12;21)(q12;q22)--is associated with a favourable prognosis. The examination of these rearrangements is important for the stratification of patients to the risk groups and also provides the most sensitive and specific tool for minimal residual disease (MRD) follow-up. METHODS AND RESULTS: This study comprises 241 patients with ALL from Czech and Slovak Republics younger than 18 years at diagnosis. They were examined for presence of m-RNA of fusion genes BCR/ABL, MLL/AF4 and TEL/AML1 by reverse transcriptase-polymerase chain reaction (RT-PCR) method. Seven out of 197 (3.6%) carried MLL/AF4 fusion gene, but among infants it was 56% (5 out of 9). BCR/ABL positivity was found in 2.5% (7 out of 240) and TEL/AML1 in 21.7% (41 out of 189) cases. Event free survival (EFS) curves demonstrate the clinical impact of these hybrid genes on patients' prognosis. Moreover, we present the possibility of the monitoring of MRD levels in follow-up samples of these patients. CONCLUSIONS: All particular rearrangements were found only in a cohort of patients with B-precursor ALL (or hybrid leukaemia), which constitutes 85% of our group. Presence of BCR/ABL or MLL/AF4 fusion gene is associated with poor prognosis and is indispensable condition for correct stratification of patients to the risk groups according to treatment protocols. Hybrid gene TEL/AML1 defines subgroup of children with better prognosis and due to its high frequency provides us with a very useful tool for MRD detection.

Biomarkers, Tumor↗
PubMed1999

[Study of TEL-AML1 fusion gene in childhood B-lineage acute lymphoblastic leukemia].

OBJECTIVE: To determine the incidence of TEL-AML1 fusion gene and its role in clinical diagnosis and prognosis of childhood B-lineage acute lymphoblastic leukemia (B-ALL), and to compare the two techniques: nested RT-PCR and dual-color fluorescence in situ hybridization (FISH). METHODS: Nested RT-PCR and dual-color FISH techniques were used to detect TEL-AML1 fusion gene. RESULTS AND CONCLUSION: TEL-AML1 fusion transcript was found in 22.5%(9/40) of patients with B-ALL by RT-PCR. The prognosis of these TEL-AML1 positive patients was relatively good and the complete remission rate was 100%. Both RT-PCR and FISH techniques were proved to be useful for detecting TEL-AML1 fusion gene and suitable for clinical diagnosis and prognosis evaluation.

Adolescent↗
PubMed2004

[Study of the childhood acute lymphoblastic leukemia with t(12;21)].

OBJECTIVE: To explore the incidence, clinical characteristics and prognosis of childhood acute lymphoblastic leukemia (ALL) with t(12;21). METHODS: t(12;21)/TEL-AML1 fusion gene was examined in bone marrow or peripheral blood mononuclear cells from 51 newly diagnosed childhood ALL patients by conventional cytogenetic R-banding analysis (CCA), dual colour interphase fluorescence in situ hybridization (I-FISH), and nested reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: t(12; 21)/TEL-AML1 fusion gene was found in 11 cases by FISH or PCR, accounting for 21.6% and 26.9% in childhood ALLs and in non-T lineage ALL cases, respectively. The median age at diagnosis was 6.8 (2.9 to 12) years. All of the t(12;21) patients expressed non-T lineage immunophenotype, and most of them were common-ALL. High myeloid antigen coexpression was not found. In 11 CCA cases, normal karyotype was found in 7, and a dubious t(12;21) in one. TEL allele deletion was found in 8 (72.7%) of t(12;21) positive cases by FISH. By comparison, no statistic difference was found in sex, anemia, hemorrhage, organ enlargement, and initial WBC count between the positive and negative non-T lineage ALLs, but the platelet count and the frequency of IgH gene rearrangement were much lower in positive cases (P = 0.008 and 0.007, respectively). Moreover, no difference was found in overall CR rate, CR rate within 4 weeks, CR duration and relapse rate between the two groups. CONCLUSION: t(12;21) was the most common chromosomal translocation in childhood ALL, but not all of them could be detected by CCA. t(12;21) cases showed non-T cell immunotypes, most of them were CD(10)(+) ALL. TEL allele deletion was common in these cases. There was no significant difference in clinical characteristics and short term outcome between the t(12;21) and the TEL-AML1 negative cases. In our data, Chinese t(12;21) ALL showed older in age, lower BPC, lower IgH rearrangement frequency and more of normal karyotype as compared with the reports abroad.

Child↗
PubMedDate not supplied

The ETS-related factor TEL is regulated by angiogenic growth factor VEGF in HUVE-cells.

Angiogenesis is a multistage process that requires, at its early stages, proliferation of endothelial cells, the break down of the basement membrane, and subsequent budding of new vessel-like structures. The regulation of the process of endothelial cell proliferation and migration during angiogenesis involves the ETS family of transcription factors. The TEL gene is an ETS family transcription factor that may play a role in vessel formation. VEGF is a specific growth factor in vessel formation and in this study its regulatory effects on TEL gene expression are detailed. Moreover, it was shown that the effects of VEGF are mediated through the MAP kinase pathway via ERK2. In conclusion, TEL protein is endogenously expressed by HUVE-Cells during normal growth.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed2005

Late ovarian relapse of TEL/AML1 positive ALL confirming that TEL deletion is a secondary event in leukemogenesis.

We describe here a late extramedullary ovarian relapse in an 18-year-old female who was diagnosed with hypotetraploid cell acute lymphoblastic leukaemia (cALL) at the age of 6. At both occurrences of the disease cells were analyzed by morphology, immunophenotyping, cytogenetics and molecular methods. TEL/AML1 was detected by RT-PCR and FISH analysis in both events. We demonstrated, using detection of IGH/TCR rearrangements and TEL/AML1 breakpoints sequencing that the cells were clonally related. Moreover, interphasic FISH using TEL and AML1 probes showed the loss of a second TEL at the time of relapse. This observation confirms that TEL/AML1 alone is not sufficient to trigger ALL and that TEL deletion is a secondary event in leukemogenesis. To our knowledge, it is the first complete description of extramedullary ALL relapse combining all methodologies.

Adolescent↗
PubMed1999

The leukemia-associated gene TEL encodes a transcription repressor which associates with SMRT and mSin3A.

The E-26 transforming specific (ETS)-related gene TEL, also known as ETV6, encodes a strong transcription repressor that is rearranged in several recurring chromosomal rearrangements associated with leukemia and congenital fibrosarcoma. The TEL protein contains two functional domains that have been partially characterized: a helix-loop-helix (HLH) domain (also known as a pointed domain) at the N-terminus, which physically interacts with itself, with the SUMO-conjugating enzyme UBC9, and with FLI1; and, at the C-terminus, an ETS domain with DNA-binding properties. Little is known about the function of the central region of TEL. The HLH domain and the central region of TEL are consistently maintained in the t(12;21), which is the most frequent chromosomal translocation involving TEL. In this study, we found that the HLH domain and the central region of TEL mediate transcription repression by two distinct mechanisms. The central region involves the recruitment of a repression complex, including SMRT and mSin3A. The HLH domain represses gene transcription through a mechanism that is independent of known corepressors. Thus, TEL belongs to a growing number of transcription factors rearranged by chromosomal translocations that are associated with the corepressor complexes.

3T3 Cells↗
PubMed2004

Prenatal origin of separate evolution of leukemia in identical twins.

Several studies involving identical twins with concordant leukemia and retrospective scrutiny of archived neonatal blood spots have shown that the TEL-AML1 fusion gene in childhood acute lymphoblastic leukemia (ALL) frequently arises before birth. A prenatal origin of childhood leukemia was further supported by the detection of clonotypic immunoglobulin gene rearrangements on neonatal blood spots of children with various other subtypes of ALL. However, no comprehensive study is available linking these clonotypic events. We describe a pair of 5-year-old monozygotic twins with concordant TEL-AML1-positive ALL. Separate leukemic clones were identified in the diagnostic samples since distinct IGH and IGK-Kde gene rearrangements could be detected. Additional differences characterizing the leukemic clones included an aberration of the second, nonrearranged TEL allele observed in one twin only. Interestingly, both the identical TEL-AML1 fusion sequence and distinct immunoglobulin gene rearrangements were identified on the neonatal blood spots indicating that separate preleukemic clones evolved already before birth. Finally, we compared the reported twins with an additional 31 children with ALL by using the microarray technology. Gene expression profiling provided evidence that leukemia in twins harbours the same subtype-typical feature as TEL-AML1-positive leukemia in singletons suggesting that the leukemogenesis model might also be applicable generally.

Base Sequence↗
PubMed1999

Low frequency of the TEL/AML1 fusion gene in acute lymphoblastic leukaemia in Spain.

We report on a series of Spanish patients with acute lymphoblastic leukaemia in whom the t(12;21) [TEL/AML1] translocation could not be identified with two sensitive techniques: reverse transcript-polymerase chain reaction (RT-PCR) and fluorescence in-situ hybridization (FISH). 101 cases were analysed: 38 children (29 B-cell precursor; nine T-cell precursor) and 63 adults (48 B-cell precursor; 15 T-cell precursor). Specific RT-PCR to amplify the TEL/AML1 fusion transcript was negative in all 101 cases. Moreover, all 38 paediatric samples were also negative by interphase FISH analysis for the presence of the TEL/AML1 fusion. These results suggest the existence of geographic/race variations in the genotype of acute lymphoblastic leukaemia (ALL).

Adolescent↗
PubMed2000

TEL-AML1 fusion gene frequency in paediatric acute lymphoblastic leukaemia in Brazil.

We analysed 67 samples from Brazilian children of diverse ethnic origins with acute lymphoblastic leukaemia (ALL) for the presence of the TEL-AML1 fusion gene transcripts using reverse transcription polymerase chain reaction (RT-PCR). All 12 positive cases (20% of the 60 B-cell precursor ALL) had common (CD10+) ALL with a mean age of 4 years (range 1-10 years). We conclude that the frequency, age, distribution and clinical features of the TEL-AML1 fusion gene-positive ALL is similar in the diverse ethnic backgrounds of the Brazilian children to that in other countries with predominantly white Caucasian or oriental ethnicity. Apparent exceptions to this generality are discussed.

Black People↗
PubMed2006

Preleukemic TEL-AML1-positive clones at cell level of 10(-3) to 10(-4) do not persist into adulthood.

The TEL-AML1 translocation, t(12;21)(p13;q22), is one of the most frequent genetic aberrations in childhood B-cell precursor acute lymphoblastic leukemia (ALL), where it occurs in 25% of all cases. In contrast, the translocation is seen in only 3% of adult ALL cases. Evidence suggests that the TEL-AML1 translocation occurs in utero in 1% of all newborn children at cell levels of 10 to 10. In this study, we explore the prevalence of TEL-AML1-positive cells in 2 cohorts of healthy blood donors by real-time and nested reverse transcription-polymerase chain reaction. Overall, TEL-AML1-positive cells were demonstrated in 10 of 2005 healthy donors, that is, a prevalence of 0.5% (95% confidence interval, 0.2-0.3%). The level of TEL-AML1-positive cells was estimated to 10 to 10. The observed prevalence of TEL-AML1-positive cells in healthy adults is of the same order of magnitude as the prevalence reported in healthy newborns, but the observed cell level of 10 to 10 is much lower. These data indicates that prenatal TEL-AML1 subclones does not persist throughout adult life at cell levels of 10 to 10. The findings are compatible with the risk of t(12;21)(p13;q22) ALL correlating with the total number of TEL-AML1-positive cells in peripheral blood in both childhood and adulthood.

Adult↗