Suppressed CEBPA Function Is Associated with Favorable Prognosis in Normal Karyotype AML Patients

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2506-2506
Author(s):  
Jose Fos ◽  
Nicola Bonadies ◽  
Thomas Pabst ◽  
Beatrice U Mueller
Keyword(s):  
Transcription Factor ◽  
De Novo ◽  
Prognostic Significance ◽  
Normal Karyotype ◽  
Binding Activity ◽  
Leukemic Cells ◽  
Prognostic Information ◽  
Independent Prognostic Marker ◽  
Favorable Prognosis ◽  
Dna Binding Activity

Abstract The myeloid transcription factor CEBPA is crucial for normal differentiation of granulocytes. In addition, genomic mutations and deregulated expression of CEBPA have been reported in specific subsets of patients with acute myeloid leukemia (AML). We here investigated the prognostic significance of CEBPA mRNA, CEBPA protein, and CEBPA function in 105 consecutive de novo AML patients with a particular focus on AML patients with a normal karyotype. We found that the DNA binding activity of CEBPA in normal karyotype AML patients as determined by an ELISA-based assay conferred significant prognostic information: normal karyotype AML patients with suppressed CEBPA function showed a better OS (p=0.0068) and DFS (p=0.0138) compared to patients with conserved CEBPA function. In addition, suppressed levels of the 42kDa CEBPA protein in these patients tended to predict favorable outcome, whereas differences in p30 CEBPA protein levels and in mRNA expression did not affect the outcome. Finally, AML patients with suppressed CEBPA function had more frequently FLT3-ITD and an unmutated nucleophosmin status identifying CEBPA function as an independent prognostic marker for normal karyotype AML. This is the first study comprehensively assessing CEBPA transcription factor function in leukemic cells from AML patients. Our data suggest that suppressed CEBPA function is associated with favorable prognosis in normal karyotype AML patients independently of other molecular markers, and we propose assessment of CEBPA binding activity to be integrated into clinical practice. Moreover, our results highlight the importance of posttranscriptional mechanisms of CEBPA modulation in AML.

The Re-Activation of FoxO3 Transcription Factor in Acute Myeloid Leukaemia Is Responsible for the Induction of a Quiescent Status of Leukaemic Progenitor Cells.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 929-929
Author(s):  
Daniela Cilloni ◽  
Cristina Panuzzo ◽  
Francesca Arruga ◽  
Francesca Messa ◽  
Monica Pradotto ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Transcription Factor ◽  
Stem Cell ◽  
Dna Binding ◽  
Prognostic Significance ◽  
Binding Activity ◽  
Cell Compartment ◽  
Transfected Cells ◽  
Dna Binding Activity ◽  
Acute Myeloid

Abstract The FoxO transcription factor promotes apoptosis and triggers cell cycle inhibition through multiple mechanisms. It is inactivated by PI3K/Akt induced phosphorylation thus resulting in nuclear exclusion and degradation. Moreover, several data demonstrated an abnormal activation of PI3K/Akt pathway in acute myeloid leukemia (AML) with contrasting prognostic significance. The aim of this study was to clarify the role of FoxO3 in AML and to investigate alternative pathways eventually responsible for FoxO3 inactivation. Importantly, we explore the effects of FoxO3 re-activation in CD34+ AML cells. Cell cycle was analyzed by FACS in CD34+ cell population as well as the levels of CD47, which has been demonstrated to increased during progression through the cell cycle and stem cell mobilization. Protein amount and localization were analyzed by Western blot and immunofluorescence, the DNA binding activity was measured by EMSA. 35 BM samples from AML patients at diagnosis and in 20 healthy donors were analyzed. Furthermore Spred1, known to be a FoxO3 target gene was quantified by RQ-PCR. We previously described the absence of Spred1 in AML patients and demonstrated that it promotes growth arrest and apoptosis in haematopoietic cells. Finally BM cells were incubated with a PI3K inhibitor LY294002 and the IKK inhibitor PS1145, alone and in combination. Moreover, the t(8;21) positive Kasumi cell line was transfected with pECE-FoxO3 to evaluate FoxO3 effects on cell growth and apoptosis. We found that, while FoxO3 in control cells is localized in both nucleus (mean value of intensity of 21,4 ±2) and cytoplasm (14,6±1,7), it is completely cytoplasmatic in AML cells (18,1±4,6 in cytoplasm vs 8,2±4 in the nucleus) and enters the nucleus after chemotherapy or in vitro incubation with LY29400. Moreover, FoxO3 DNA binding activity in AML patients is completely absent at diagnosis and restored after therapy. Also the mRNA of Spred1 is rather undetectable at diagnosis (2−ΔΔCt= 0,009±0,3) and shows normal levels during remission (2−ΔΔCt = 2±1,5) or after LY29400 incubation (2−ΔΔCt =0,8±0,3). In addition LY294002 and PS1145 treatment results in FoxO3 partial nuclear re-localization while their association induces a complete nuclear shuttle suggesting that both pathways could be implicated in FoxO3 inactivation. The restoring of FoxO3 function by LY29400 in CD34+ cells induces quiescence of this progenitor cell compartment as demonstrated by the comparison of cell cycle kinetics and the decreased expression of CD47 (p=0,01). Finally, FoxO3 overexpression in transfected cells results in a block of proliferation rate (66% of inhibition compared to empty vector transfected cells) and apoptosis induction (35% vs 12%). Taken together these data suggest that FoxO3 inactivation may be crucial for the leukemic progression and demonstrate that also IKK pathway contributes to this effect, providing the rationale for a therapeutic strategy. On the other hand, the re-activation of FoxO3 induces quiescence of the stem cell compartment so providing a mechanism of escape from chemotherapy induced apoptosis.

scholarly journals Suppression of E1A-Mediated Transformation by the p50E4F Transcription Factor

1999 ◽  
Vol 19 (7) ◽  
pp. 4739-4749 ◽  
Author(s):  
Elma R. Fernandes ◽  
Robert J. Rooney
Keyword(s):  
Cell Death ◽  
Transcription Factor ◽  
Suppressive Effect ◽  
Culture Conditions ◽  
Binding Activity ◽  
Cellular Transcription Factor ◽  
Dna Binding Activity ◽  
3T3 Fibroblasts ◽  
Induced Apoptosis ◽  
Nih 3T3

ABSTRACT The adenovirus E1A gene can act as an oncogene or a tumor suppressor, with the latter effect generally arising from the induction of apoptosis or the repression of genes that provide oncogenic growth stimuli (e.g., HER-2/c-erbB2/neu) or increased metastatic invasiveness (e.g., metalloproteases). In this study, coexpression of E1A and p50E4F, a cellular transcription factor whose DNA binding activity is stimulated by E1A, suppressed colony formation by NIH 3T3 cells and transformation of primary rat embryo fibroblasts but had no observed effect in the absence of E1A. Domains in p50E4F required for stimulation of the adenovirus E4 promoter were required for the suppressive effect, indicating a transcriptional mechanism. In serum-containing media, retroviral expression of p50E4F in E1A13S/ras-transformed NIH 3T3 fibroblasts had little effect on subconfluent cultures but accelerated a decline in viability after the cultures reached confluence. Cell death occurred by both apoptosis and necrosis, with the predominance of each process determined by culture conditions. In serum-free media, p50E4F accelerated E1A-induced apoptosis. The results suggest that p50E4F sensitizes cells to signals or conditions that cause cell death.

A single polypeptide possesses the binding and transcription activities of the adenovirus major late transcription factor

1986 ◽  
Vol 6 (12) ◽  
pp. 4723-4733
Author(s):  
L A Chodosh ◽  
R W Carthew ◽  
P A Sharp
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Binding Site ◽  
Rna Polymerase Ii ◽  
Sodium Dodecyl ◽  
Binding Activity ◽  
Affinity Column ◽  
Dna Binding Activity ◽  
Dna Fragment

A simple approach has been developed for the unambiguous identification and purification of sequence-specific DNA-binding proteins solely on the basis of their ability to bind selectively to their target sequences. Four independent methods were used to identify the promoter-specific RNA polymerase II transcription factor MLTF as a 46-kilodalton (kDa) polypeptide. First, a 46-kDa protein was specifically cross-linked by UV irradiation to a body-labeled DNA fragment containing the MLTF binding site. Second, MLTF sedimented through glycerol gradients at a rate corresponding to a protein of native molecular weight 45,000 to 50,000. Third, a 46-kDa protein was specifically retained on a biotin-streptavidin matrix only when the DNA fragment coupled to the matrix contained the MLTF binding site. Finally, proteins from the most highly purified fraction which were eluted and renatured from the 44- to 48-kDa region of a sodium dodecyl sulfate-polyacrylamide gel exhibited both binding and transcription-stimulatory activities. The DNA-binding activity was purified 100,000-fold by chromatography through three conventional columns plus a DNA affinity column. Purified MLTF was characterized with respect to the kinetic and thermodynamic properties of DNA binding. These parameters indicate a high degree of occupancy of MLTF binding sites in vivo.

Cloning and characterization of E2F-2, a novel protein with the biochemical properties of transcription factor E2F

1993 ◽  
Vol 13 (12) ◽  
pp. 7802-7812
Author(s):  
M Ivey-Hoyle ◽  
R Conroy ◽  
H E Huber ◽  
P J Goodhart ◽  
A Oliff ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dna Binding ◽  
Hela Cell ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Amino Acid Identity ◽  
Biochemical Properties ◽  
Binding Activity ◽  
Dna Binding Activity ◽  
Novel Protein

E2F is a mammalian transcription factor that appears to play an important role in cell cycle regulation. While at least two proteins (E2F-1 and DP-1) with E2F-like activity have been cloned, studies from several laboratories suggest that additional homologs may exist. A novel protein with E2F-like properties, designated E2F-2, was cloned by screening a HeLa cDNA library with a DNA probe derived from the DNA binding domain of E2F-1 (K. Helin, J. A. Lees, M. Vidal, N. Dyson, E. Harlow, and A. Fattaey, Cell 70:337-350, 1992). E2F-2 exhibits overall 46% amino acid identity to E2F-1. Both the sequence and the function of the DNA and retinoblastoma gene product binding domains of E2F-1 are conserved in E2F-2. The DNA binding activity of E2F-2 is dramatically enhanced by complementation with particular sodium dodecyl sulfate-polyacrylamide gel electrophoresis-purified components of HeLa cell E2F, and anti-E2F-2 antibodies cross-react with components of purified HeLa cell E2F. These observations are consistent with a model in which E2F binds DNA as a heterodimer of two distinct proteins, and E2F-2 is functionally and immunologically related to one of these proteins.

scholarly journals Clinical, morphologic, and cytogenetic characteristics of 26 patients with acute erythroblastic leukemia

Blood ◽  
1992 ◽  
Vol 80 (11) ◽  
pp. 2873-2882 ◽  
Author(s):  
OI Olopade ◽  
M Thangavelu ◽  
RA Larson ◽  
R Mick ◽  
A Kowal-Vern ◽  
...  
Keyword(s):  
Myeloid Leukemia ◽  
De Novo ◽  
Chromosomal Abnormalities ◽  
Normal Karyotype ◽  
Intensive Chemotherapy ◽  
Trisomy 8 ◽  
Cytogenetic Abnormalities ◽  
Favorable Prognosis ◽  
Multiple Abnormalities ◽  
French American British

Abstract We have performed a retrospective analysis of the clinical, morphologic, and cytogenetic findings in 26 patients diagnosed between January 1969 and September 1991 with acute erythroblastic leukemia de novo (EL or AML-M6). Clonal chromosomal abnormalities were found in 20 (77%) patients (95% confidence interval [CI], 61% to 93%). Loss of all or part of the long arm (q) of chromosomes 5 and/or 7 was observed in 17 (65%) patients (95% CI, 47% to 83%). In addition, the karyotypes were often complex, with multiple abnormalities and subclones. Among the remaining nine patients, six had a normal karyotype and one each had trisomy 8, t(3;3), or t(3;5). The overall frequency of abnormalities of chromosomes 5 and/or 7 observed in our M6 patients is similar to that observed in our patients with therapy-related acute myeloid leukemia (t-AML; 99 of 129 patients, 77%), but substantially higher than that noted in our other patients with AML de novo (French- American-British [FAB] subtypes M1-M5: 52 of 334 patients, 16%). Our M6 patients with abnormalities of chromosomes 5 and/or 7 were older and had a shorter median survival (16 v 77 weeks [P = .005]) than did the M6 patients without these abnormalities. We found no correlation between morphologic features and either cytogenetic abnormalities or clinical outcome. Of note was the finding that the percentage of myeloblasts, which may account for only a small fraction of the total marrow elements when the revised FAB criteria are applied, had no bearing on prognosis. We conclude that acute erythroblastic leukemia, when defined by morphologic criteria, consists of two distinctive subgroups: one group tends to be older, has complex cytogenetic abnormalities, especially of chromosomes 5 and/or 7, and shares biologic and clinical features with t-AML; the other group, with simple or no detectable cytogenetic abnormalities, has a more favorable prognosis when treated with intensive chemotherapy.

Treatment of cultured myotubes with the proteasome inhibitor β-lactone increases the expression of the transcription factor C/EBPβ

2007 ◽  
Vol 292 (1) ◽  
pp. C216-C226 ◽  
Author(s):  
Wei Wei ◽  
Hongmei Yang ◽  
Michael Menconi ◽  
Peirang Cao ◽  
Chester E. Chamberlain ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Transcription Factor ◽  
Dna Binding ◽  
Proteasome Inhibitor ◽  
Binding Activity ◽  
Dominant Negative ◽  
Dna Binding Activity ◽  
Cultured Myotubes ◽  
Nuclear Levels ◽  
Factor C

The role of the proteasome in the regulation of cellular levels of the transcription factor CCAAT/enhancer-binding protein β (C/EBPβ) is poorly understood. We tested the hypothesis that C/EBPβ levels in cultured myotubes are regulated, at least in part, by proteasome activity. Treatment of cultured L6 myotubes, a rat skeletal muscle cell line, with the specific proteasome inhibitor β-lactone resulted in increased nuclear levels of C/EBPβ as determined by Western blotting and immunofluorescent detection. This effect of β-lactone reflected inhibited degradation of C/EBPβ. Surprisingly, the increased C/EBPβ levels in β-lactone-treated myotubes did not result in increased DNA-binding activity. In additional experiments, treatment of the myotubes with β-lactone resulted in increased nuclear levels of growth arrest DNA damage/C/EBP homologous protein (Gadd153/CHOP), a dominant-negative member of the C/EBP family that can form heterodimers with other members of the C/EBP family and block DNA binding. Coimmunoprecipitation and immunofluorescent detection provided evidence that C/EBPβ and Gadd153/CHOP interacted and colocalized in the nuclei of the β-lactone-treated myotubes. When Gadd153/CHOP expression was downregulated by transfection of myotubes with siRNA targeting Gadd153/CHOP, C/EBPβ DNA-binding activity was restored in β-lactone-treated myotubes. The results suggest that C/EBPβ is degraded by a proteasome-dependent mechanism in skeletal muscle cells and that Gadd153/CHOP can interact with C/EBPβ and block its DNA-binding activity. The observations are important because they increase the understanding of the complex regulation of the expression and activity of C/EBPβ in skeletal muscle.

scholarly journals Two monomers of yeast transcription factor ADR1 bind a palindromic sequence symmetrically to activate ADH2 expression.

1991 ◽  
Vol 11 (3) ◽  
pp. 1566-1577 ◽  
Author(s):  
S K Thukral ◽  
A Eisen ◽  
E T Young
Keyword(s):  
Transcription Factor ◽  
Amino Acid ◽  
Dna Binding ◽  
Dimethyl Sulfate ◽  
Binding Activity ◽  
Single Amino Acid ◽  
Minor Effect ◽  
Palindromic Sequence ◽  
Amino Terminal ◽  
Dna Binding Activity

ADR1 is a transcription factor from Saccharomyces cerevisiae that regulates ADH2 expression through a 22-bp palindromic sequence (UAS1). Size fractionation studies revealed that full-length ADR1 and a truncated ADR1 protein containing the first 229 amino acids, which has the complete DNA-binding domain, ADR1:17-229, exist as monomers in solution. However, two complexes were formed with target DNA-binding sites. UV-cross-linking studies suggested that these two complexes represent one and two molecules of ADR1 bound to DNA. Studies of ADR1 complexes formed with wild-type UAS1, asymmetrically altered UAS1, and one half of UAS1 showed that ADR1 can bind to one half of UAS1 and gives rise to a complex containing one molecule of ADR1. Dimethyl sulfate interference studies were consistent with this interpretation and in addition indicated that purine contact sites in each half of UAS1 were identical. Increasing the distance between the two halves of UAS1 had at most a minor effect of the thermodynamics of formation of the two complexes. These data are more consistent with ADR1 binding as two independent monomers, one to each half of UAS1. However, binding of two ADR1 monomers at UAS1 is apparently essential for transactivation in vivo. Further, we have identified a stretch of 18 amino acid residues amino terminal to the zinc two-finger domains of ADR1 which is essential for DNA-binding activity. Single amino acid substitutions of residues in this region resulted in severely reduced DNA-binding activity.

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