scholarly journals Characterization of the Retinoid Binding Properties of the Major Fusion Products Present in Acute Promyelocytic Leukemia Cells

Blood ◽  
1997 ◽  
Vol 90 (3) ◽  
pp. 1175-1185 ◽  
Author(s):  
Laura Benedetti ◽  
Arthur A. Levin ◽  
Bianca M. Scicchitano ◽  
Francesco Grignani ◽  
Gary Allenby ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Acute Promyelocytic Leukemia ◽  
Transcriptional Activation ◽  
Retinoic Acid Receptor ◽  
Promyelocytic Leukemia ◽  
Binding Assays ◽  
Binding Properties ◽  
All Trans Retinoic Acid ◽  
Structural And Functional Properties ◽  
Retinoic Acid Receptor Α

Abstract The bcr1- and bcr3- promyelocytic leukemia/retinoic acid receptor α (PML/RARα) are the two major fusion proteins expressed in acute promyelocytic leukemia (APL) patients. These proteins, which are present in different lengths of PML (amino acids 1-552 and 1-394, respectively), contain most of the functional domains of PML and RARα, bind all-trans-retinoic acid (t-RA), and act as t-RA–dependent transcription factors. T-RA is an effective inducer of clinical remission only in patients carrying the t(15; 17) and expressing the PML/RARα products. However, in APL patients achieving complete remission with t-RA therapy the bcr3-PML/RARα product has been found associated with a poorer prognosis than bcr1-PML/RARα. In the present study we have investigated the structural and functional properties of the bcr3-PML/RARα in comparison to the previously characterized bcr1-PML/RARα. In particular, we have measured the binding properties of the two endogenous ligands t-RA and 9-cis-RA to both of these isoforms. T-RA binding analysis of nuclear and cytosolic extracts prepared from bcr3-PML/RARα APL patients and from bcr3-PML/RARα COS-1 transfected cells indicates that this protein is present only as high-molecular-weight nuclear complexes. Using saturation binding assays and Scatchard analyses we found that t-RA binds with slightly less affinity to the bcr3-PML/RARα receptor than to bcr1-PML/RARα or RARα (Kd = 0.4 nmol/L, 0.13 nmol/L or 0.09 nmol/L, respectively). Moreover, two different high-affinity 9-cis-RA binding sites (Kd = 0.45 and 0.075 nmol/L) were detectable in the bcr3-PML/RARα product but not in the bcr1-PML/RARα product (Kd = 0.77 nmol/L). By competition binding experiments we showed that 9-cis-RA binds with higher specificity to the bcr3-PML/RARα isoform than to the bcr1-PML/RARα or RARα. Consistent with these data, the binding of 9-cis-RA to the bcr3-PML/RARα product resulted in increased transcriptional activation of the RA-responsive element (RARE) TRE, but not of the βRARE, in transiently transfected COS-1 cells. These results provide evidence indicating that preferential retinoid binding to the different PML/RARα products can be measured.

scholarly journals Characterization of the Retinoid Binding Properties of the Major Fusion Products Present in Acute Promyelocytic Leukemia Cells

Blood ◽  
1997 ◽  
Vol 90 (3) ◽  
pp. 1175-1185 ◽  
Author(s):  
Laura Benedetti ◽  
Arthur A. Levin ◽  
Bianca M. Scicchitano ◽  
Francesco Grignani ◽  
Gary Allenby ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Acute Promyelocytic Leukemia ◽  
Transcriptional Activation ◽  
Retinoic Acid Receptor ◽  
Promyelocytic Leukemia ◽  
Binding Assays ◽  
Binding Properties ◽  
All Trans Retinoic Acid ◽  
Structural And Functional Properties ◽  
Retinoic Acid Receptor Α

The bcr1- and bcr3- promyelocytic leukemia/retinoic acid receptor α (PML/RARα) are the two major fusion proteins expressed in acute promyelocytic leukemia (APL) patients. These proteins, which are present in different lengths of PML (amino acids 1-552 and 1-394, respectively), contain most of the functional domains of PML and RARα, bind all-trans-retinoic acid (t-RA), and act as t-RA–dependent transcription factors. T-RA is an effective inducer of clinical remission only in patients carrying the t(15; 17) and expressing the PML/RARα products. However, in APL patients achieving complete remission with t-RA therapy the bcr3-PML/RARα product has been found associated with a poorer prognosis than bcr1-PML/RARα. In the present study we have investigated the structural and functional properties of the bcr3-PML/RARα in comparison to the previously characterized bcr1-PML/RARα. In particular, we have measured the binding properties of the two endogenous ligands t-RA and 9-cis-RA to both of these isoforms. T-RA binding analysis of nuclear and cytosolic extracts prepared from bcr3-PML/RARα APL patients and from bcr3-PML/RARα COS-1 transfected cells indicates that this protein is present only as high-molecular-weight nuclear complexes. Using saturation binding assays and Scatchard analyses we found that t-RA binds with slightly less affinity to the bcr3-PML/RARα receptor than to bcr1-PML/RARα or RARα (Kd = 0.4 nmol/L, 0.13 nmol/L or 0.09 nmol/L, respectively). Moreover, two different high-affinity 9-cis-RA binding sites (Kd = 0.45 and 0.075 nmol/L) were detectable in the bcr3-PML/RARα product but not in the bcr1-PML/RARα product (Kd = 0.77 nmol/L). By competition binding experiments we showed that 9-cis-RA binds with higher specificity to the bcr3-PML/RARα isoform than to the bcr1-PML/RARα or RARα. Consistent with these data, the binding of 9-cis-RA to the bcr3-PML/RARα product resulted in increased transcriptional activation of the RA-responsive element (RARE) TRE, but not of the βRARE, in transiently transfected COS-1 cells. These results provide evidence indicating that preferential retinoid binding to the different PML/RARα products can be measured.

scholarly journals ATRA resolves the differentiation block in t(15;17) acute myeloid leukemia by restoring PU.1 expression

Blood ◽  
2006 ◽  
Vol 107 (8) ◽  
pp. 3330-3338 ◽  
Author(s):  
Beatrice U. Mueller ◽  
Thomas Pabst ◽  
José Fos ◽  
Vibor Petkovic ◽  
Martin F. Fey ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Retinoic Acid ◽  
Acute Promyelocytic Leukemia ◽  
Myeloid Leukemia ◽  
Retinoic Acid Receptor ◽  
Promyelocytic Leukemia ◽  
All Trans Retinoic Acid ◽  
Conditional Expression ◽  
Neutrophil Differentiation ◽  
Acute Myeloid

Abstract Tightly regulated expression of the transcription factor PU.1 is crucial for normal hematopoiesis. PU.1 knockdown mice develop acute myeloid leukemia (AML), and PU.1 mutations have been observed in some populations of patients with AML. Here we found that conditional expression of promyelocytic leukemia-retinoic acid receptor α (PML-RARA), the protein encoded by the t(15;17) translocation found in acute promyelocytic leukemia (APL), suppressed PU.1 expression, while treatment of APL cell lines and primary cells with all-trans retinoic acid (ATRA) restored PU.1 expression and induced neutrophil differentiation. ATRA-induced activation was mediated by a region in the PU.1 promoter to which CEBPB and OCT-1 binding were induced. Finally, conditional expression of PU.1 in human APL cells was sufficient to trigger neutrophil differentiation, whereas reduction of PU.1 by small interfering RNA (siRNA) blocked ATRA-induced neutrophil differentiation. This is the first report to show that PU.1 is suppressed in acute promyelocytic leukemia, and that ATRA restores PU.1 expression in cells harboring t(15;17).

scholarly journals PLZF-RARα, NPM1-RARα, and Other Acute Promyelocytic Leukemia Variants: The PETHEMA Registry Experience and Systematic Literature Review

Cancers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1313 ◽  
Author(s):  
Marta Sobas ◽  
Maria Carme Talarn-Forcadell ◽  
David Martínez-Cuadrón ◽  
Lourdes Escoda ◽  
María J. García-Pérez ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Complete Remission ◽  
Acute Promyelocytic Leukemia ◽  
Fusion Gene ◽  
Retinoic Acid Receptor ◽  
Promyelocytic Leukemia ◽  
High Relapse Rate ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid ◽  
Shed Light

It has been suggested that 1–2% of acute promyelocytic leukemia (APL) patients present variant rearrangements of retinoic acid receptor alpha (RARα) fusion gene, with the promyelocytic leukaemia zinc finger (PLZF)/RARα being the most frequent. Resistance to all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) has been suggested in PLZF/RARα and other variant APLs. Herein, we analyze the incidence, characteristics, and outcomes of variant APLs reported to the multinational PETHEMA (Programa para el Tratamiento de Hemopatias Malignas) registry, and we perform a systematic review in order to shed light on strategies to improve management of these extremely rare diseases. Of 2895 patients with genetically confirmed APL in the PETHEMA registry, 11 had variant APL (0.4%) (9 PLZF-RARα and 2 NPM1-RARα), 9 were men, with median age of 44.6 years (3 months to 76 years), median leucocytes (WBC) 16.8 × 109/L, and frequent coagulopathy. Eight patients were treated with ATRA plus chemotherapy-based regimens, and 3 with chemotherapy-based. As compared to previous reports, complete remission and survival was slightly better in our cohort, with 73% complete remission (CR) and 73% survival despite a high relapse rate (43%). After analyzing our series and performing a comprehensive and critical review of the literature, strong recommendations on appropriate management of variant APL are not possible due to the low number and heterogeneity of patients reported so far.

Extramedullary Involvement at Relapse in Acute Promyelocytic Leukemia Patients Treated or Not With All-Trans Retinoic Acid: A Report by the Gruppo Italiano Malattie Ematologiche dell’Adulto

2001 ◽  
Vol 19 (20) ◽  
pp. 4023-4028 ◽  
Author(s):  
Giorgina Specchia ◽  
Francesco Lo Coco ◽  
Marco Vignetti ◽  
Giuseppe Avvisati ◽  
Paola Fazi ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Acute Promyelocytic Leukemia ◽  
Retinoic Acid Receptor ◽  
Promyelocytic Leukemia ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid ◽  
Increased Risk ◽  
Junction Type ◽  
Wbc Count

PURPOSE: Recent reports of extramedullary disease (EMD) at recurrence in acute promyelocytic leukemia (APL) have raised increasing concern about a possible role of retinoic acid (RA) therapy. PATIENTS AND METHODS: We analyzed the risk of developing EMD localization at relapse in APL patients enrolled onto two consecutive studies of the Gruppo Italiano Malattie Ematologiche dell’Adulto. The studies investigated chemotherapy alone (LAP0389) versus RA plus chemotherapy (AIDA). RESULTS: When all relapse types were taken into account, 94 (51%) of 184 patients and 131 (18%) of 740 patients who attained hematologic remission underwent relapse in the LAP0389 and AIDA studies, respectively (P < .0001). EMD localization was documented in five (5%) of 94 and 16 (12%) of 131 patients (P = .08). Hematologic and/or molecular relapse was diagnosed concomitantly in all but two patients with EMD in the AIDA study. For patients in the LAP0389 and AIDA series, the probability of EMD localization of any type at relapse was 3% and 4.5%, respectively (P = .79), while the probability of CNS involvement was 0.6% and 2% (P = .28). No significant differences were found with regard to mean WBC count and promyelocytic leukemia/retinoic acid receptor-alpha junction type in comparisons of patients with EMD and hematologic relapse. CONCLUSION: APL patients receiving all-trans retinoic acid in addition to chemotherapy have no increased risk of developing EMD at relapse as compared with those treated with chemotherapy alone.

The t(5;17) acute promyelocytic leukemia fusion protein NPM-RAR interacts with co-repressor and co-activator proteins and exhibits both positive and negative transcriptional properties

Blood ◽  
2000 ◽  
Vol 95 (8) ◽  
pp. 2683-2690 ◽  
Author(s):  
Robert L. Redner ◽  
J. Don Chen ◽  
Elizabeth A. Rush ◽  
Hui Li ◽  
Sheri L. Pollock
Keyword(s):  
Retinoic Acid ◽  
Acute Promyelocytic Leukemia ◽  
Transcriptional Activation ◽  
Rna Splicing ◽  
Fusion Proteins ◽  
Retinoic Acid Receptor ◽  
Promyelocytic Leukemia ◽  
Dominant Negative ◽  
Wild Type ◽  
Retinoic Acid Response Element

The t(5;17) variant of acute promyelocytic leukemia (APL) fuses the genes for nucleophosmin (NPM) and the retinoic acid receptor alpha (RAR). Two NPM-RAR molecules are expressed as a result of alternative RNA splicing. Both contain RAR sequences that encode the DNA binding, heterodimerization, and ligand activation domains of RAR. This study was designed to test the ability of these fusion proteins to act as transcriptional activators of retinoic acid responsive promoters. The NPM-RAR fusion proteins bind to retinoic acid response element sequences as either homodimers or as heterodimers with RXR. Transcription of retinoic acid–inducible promoters is activated by the fusion proteins in the presence of retinoic acid. The level of transactivation induced by the NPM-RAR fusions differs from the level of transactivation induced by wild-type RAR in both a promoter and cell specific fashion, and more closely parallels the pattern of activation of the PML-RAR fusion than wild-type RAR. In addition, NPM-RAR decreases basal transcription from some promoters and acts in a dominant-negative fashion when co-transfected with wild-type RAR. Both NPM-RAR and PML-RAR interact with the co-repressor protein SMRTe in a manner that is less sensitive than RAR to dissociation by retinoic acid. Retinoic acid induces binding of the co-activator protein RAC3. These data indicate that the NPM-RAR fusion proteins can modulate expression of retinoid-responsive genes in a positive or negative manner, depending on context of the promoter, and lend support to the hypothesis that aberrant transcriptional activation underlies the APL phenotype.

scholarly journals Arsenic Trioxide Is a Potent Inhibitor of the Interaction of SMRT Corepressor with Its Transcription Factor Partners, Including the PML-Retinoic Acid Receptor α Oncoprotein Found in Human Acute Promyelocytic Leukemia

2001 ◽  
Vol 21 (21) ◽  
pp. 7172-7182 ◽  
Author(s):  
Suk-Hyun Hong ◽  
Zhihong Yang ◽  
Martin L. Privalsky
Keyword(s):  
Transcription Factor ◽  
Retinoic Acid ◽  
Acute Promyelocytic Leukemia ◽  
Potent Inhibitor ◽  
Retinoic Acid Receptor ◽  
Promyelocytic Leukemia ◽  
Map Kinase Cascade ◽  
Kinase Cascade ◽  
Retinoic Acid Receptor Α ◽  
Human Acute Promyelocytic Leukemia

ABSTRACT The SMRT corepressor complex participates in transcriptional repression by a diverse array of vertebrate transcription factors. The ability to recruit SMRT appears to play a crucial role in leukemogenesis by the PML-retinoic acid receptor α (RARα) oncoprotein, an aberrant nuclear hormone receptor implicated in human acute promyelocytic leukemia (APL). Arsenite induces clinical remission of APL through a incompletely understood mechanism. We report here that arsenite is a potent inhibitor of the interaction of SMRT with its transcription factor partners, including PML-RARα. Arsenite operates, in part, through a mitogen-activated protein (MAP) kinase cascade culminating in phosphorylation of the SMRT protein, dissociation of SMRT from its nuclear receptor partners, and a relocalization of SMRT out of the nucleus into the cytoplasm of the cell. Conversely, inhibition of this MAP kinase cascade attenuates the effects of arsenite on APL cells. Our results implicate SMRT as an important biological target for the actions of arsenite in both normal and neoplastic cells.

scholarly journals CCAAT/enhancer binding proteins alpha and epsilon cooperate with all-trans retinoic acid in therapy but differ in their antileukemic activities

Blood ◽  
2006 ◽  
Vol 108 (7) ◽  
pp. 2416-2419 ◽  
Author(s):  
Young-Jin Lee ◽  
Letetia C. Jones ◽  
Nikolai A. Timchenko ◽  
Danilo Perrotti ◽  
Daniel G. Tenen ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Binding Proteins ◽  
Retinoic Acid Receptor ◽  
Chromosomal Translocation ◽  
Promyelocytic Leukemia ◽  
Leukemic Cells ◽  
Enhancer Binding Proteins ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid ◽  
Retinoic Acid Receptor Α

Abstract CCAAT/enhancer binding proteins (C/EBPs) play critical roles in myelopoiesis. Dysregulation of these proteins likely contributes to the pathogenesis of myeloid disorders characterized by a block in granulopoiesis. In one such disease, acute promyelocytic leukemia (APL), a promyelocytic leukemia–retinoic acid receptor α (PML-RARα) fusion protein is expressed as a result of a t(15;17) chromosomal translocation. Treatment of PML-RARα leukemic cells with all-trans retinoic acid (ATRA) causes them to differentiate into mature neutrophils, an effect thought to be mediated by C/EBPs. In this study, we assess the potential for cooperativity between increased C/EBP activity and ATRA therapy. We demonstrate that although both C/EBPα and C/EBPϵ can significantly prolong survival in a mouse model of APL, they are not functionally equivalent in this capacity. We also show that forced expression of C/EBPα or C/EBPϵ in combination with ATRA treatment has a synergistic effect on survival of leukemic mice compared with either therapy alone.

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