scholarly journals A PML/RARα direct target atlas redefines transcriptional deregulation in acute promyelocytic leukemia

Blood ◽  
2020 ◽  
Author(s):  
Yun Tan ◽  
Xiaoling Wang ◽  
Huan Song ◽  
Yi Zhang ◽  
Rongsheng Zhang ◽  
...  
Keyword(s):  
Acute Promyelocytic Leukemia ◽  
Target Genes ◽  
Synergistic Effects ◽  
Chromosome Translocation ◽  
Vital Role ◽  
Promyelocytic Leukemia ◽  
Super Enhancer ◽  
Transcriptional Deregulation

Transcriptional deregulation initiated by oncogenic fusion proteins plays a vital role in leukemia. The prevailing view is that the oncogenic fusion protein PML/RARα, generated by the chromosome translocation t(15;17), functions as a transcriptional repressor in acute promyelocytic leukemia (APL). Here we provide rich evidence of how PML/RARα drives oncogenesis through both repressive and activating functions, particularly the importance of the newly identified activation role for the leukemogenesis of APL. The activating function of PML/RARα is achieved by recruiting both abundant P300 and HDAC1 and by the formation of super-enhancers. All-trans retinoic acid and arsenic trioxide, two widely used drugs in APL therapy, exert synergistic effects on controlling super-enhancer-associated PML/RARα-regulated targets in APL cells. We utilize a series of in vitro and in vivo experiments to demonstrate that PML/RARα-activated target gene GFI1 is necessary for the maintenance of APL cells, and that PML/RARα, likely oligomerized, transactivates GFI1 through chromatin conformation at the super-enhancer region. Finally, we profile GFI1 targets and reveal the interplay between GFI1 and PML/RARα on chromatin in co-regulating target genes. Our study provides genomic insight into the dual role of fusion transcription factors in transcriptional deregulation to drive leukemia development, highlighting the importance of globally dissecting regulatory circuits.

scholarly journals Synergy against PML-RARa: targeting transcription, proteolysis, differentiation, and self-renewal in acute promyelocytic leukemia

2013 ◽  
Vol 210 (13) ◽  
pp. 2793-2802 ◽  
Author(s):  
Guilherme Augusto dos Santos ◽  
Lev Kats ◽  
Pier Paolo Pandolfi
Keyword(s):  
Retinoic Acid ◽  
Acute Promyelocytic Leukemia ◽  
Target Genes ◽  
Retinoic Acid Receptor ◽  
Promyelocytic Leukemia ◽  
Nuclear Bodies ◽  
Pml Nuclear Bodies ◽  
Molecular Events

Acute promyelocytic leukemia (APL) is a hematological malignancy driven by a chimeric oncoprotein containing the C terminus of the retinoic acid receptor-a (RARa) fused to an N-terminal partner, most commonly promyelocytic leukemia protein (PML). Mechanistically, PML-RARa acts as a transcriptional repressor of RARa and non-RARa target genes and antagonizes the formation and function of PML nuclear bodies that regulate numerous signaling pathways. The empirical discoveries that PML-RARa–associated APL is sensitive to both all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO), and the subsequent understanding of the mechanisms of action of these drugs, have led to efforts to understand the contribution of molecular events to APL cell differentiation, leukemia-initiating cell (LIC) clearance, and disease eradication in vitro and in vivo. Critically, the mechanistic insights gleaned from these studies have resulted not only in a better understanding of APL itself, but also carry valuable lessons for other malignancies.

In vitro all-trans retinoic acid sensitivity of acute promyelocytic leukemia blasts: a novel indicator of poor patient outcome

Blood ◽  
2001 ◽  
Vol 98 (9) ◽  
pp. 2862-2864 ◽  
Author(s):  
Bruno Cassinat ◽  
Sylvie Chevret ◽  
Fabien Zassadowski ◽  
Nicole Balitrand ◽  
Isabelle Guillemot ◽  
...  
Keyword(s):  
Acute Promyelocytic Leukemia ◽  
Promyelocytic Leukemia ◽  
Leukemic Cells ◽  
Event Free Survival ◽  
Free Survival ◽  
Acid Sensitivity ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid

Abstract Acute promyelocytic leukemia (APL) blasts possess a unique sensitivity to the differentiating effects of all-transretinoic acid (ATRA). Multicenter trials confirm that the combination of differentiation and cytotoxic therapy prolongs survival in APL patients. However relapses still occur, and exquisite adaptation of therapy to prognostic factors is essential to aim at a possible cure of the disease. A heterogeneity was previously reported in the differentiation rate of patients' APL blasts, and it was postulated that this may reflect the in vivo heterogeneous outcome. In this study, it is demonstrated that patients of the APL93 trial whose leukemic cells achieved optimal differentiation with ATRA in vitro at diagnosis had a significantly improved event-free survival (P = .01) and lower relapse rate (P = .04). This analysis highlights the importance of the differentiation step in APL therapy and justifies ongoing studies aimed at identifying novel RA-differentiation enhancers.

scholarly journals Fucoidan enhances the therapeutic potential of arsenic trioxide and all-trans retinoic acid in acute promyelocytic leukemia, in vitro and in vivo

Oncotarget ◽  
2016 ◽  
Vol 7 (29) ◽  
pp. 46028-46041 ◽  
Author(s):  
Farzaneh Atashrazm ◽  
Ray M. Lowenthal ◽  
Joanne L. Dickinson ◽  
Adele F. Holloway ◽  
Gregory M. Woods
Keyword(s):  
Retinoic Acid ◽  
Arsenic Trioxide ◽  
Acute Promyelocytic Leukemia ◽  
Therapeutic Potential ◽  
Promyelocytic Leukemia ◽  
Trans Retinoic Acid ◽  
All Trans Retinoic Acid

scholarly journals A Retinoid-Resistant Acute Promyelocytic Leukemia Subclone Expresses a Dominant Negative PML-RARα Mutation

Blood ◽  
1997 ◽  
Vol 89 (12) ◽  
pp. 4282-4289 ◽  
Author(s):  
Wenlin Shao ◽  
Laura Benedetti ◽  
William W. Lamph ◽  
Clara Nervi ◽  
Wilson H. Miller
Keyword(s):  
Gene Expression ◽  
Retinoic Acid ◽  
Ligand Binding ◽  
Cell Line ◽  
Acute Promyelocytic Leukemia ◽  
Regulation Of Gene Expression ◽  
Promyelocytic Leukemia ◽  
Dominant Negative

Abstract The unique t(15; 17) of acute promyelocytic leukemia (APL) fuses the PML gene with the retinoic acid receptor α (RARα) gene. Although retinoic acid (RA) inhibits cell growth and induces differentiation in human APL cells, resistance to RA develops both in vitro and in patients. We have developed RA-resistant subclones of the human APL cell line, NB4, whose nuclear extracts display altered RA binding. In the RA-resistant subclone, R4, we find an absence of ligand binding of PML-RARα associated with a point mutation changing a leucine to proline in the ligand-binding domain of the fusion PML-RARα protein. In contrast to mutations in RARα found in retinoid-resistant HL60 cells, in this NB4 subclone, the coexpressed RARα remains wild-type. In vitro expression of a cloned PML-RARα with the observed mutation in R4 confirms that this amino acid change causes the loss of ligand binding, but the mutant PML-RARα protein retains the ability to heterodimerize with RXRα and thus to bind to retinoid response elements (RAREs). This leads to a dominant negative block of transcription from RAREs that is dose-dependent and not relieved by RA. An unrearranged RARα engineered with this mutation also lost ligand binding and inhibited transcription in a dominant negative manner. We then found that the mutant PML-RARα selectively alters regulation of gene expression in the R4 cell line. R4 cells have lost retinoid-regulation of RXRα and RARβ and the RA-induced loss of PML-RARα protein seen in NB4 cells, but retain retinoid-induction of CD18 and CD38. Thus, the R4 cell line provides data supporting the presence of an RARα-mediated pathway that is independent from gene expression induced or repressed by PML-RARα. The high level of retinoid resistance in vitro and in vivo of cells from some relapsed APL patients suggests similar molecular changes may occur clinically.

scholarly journals In vivo analysis of the role of aberrant histone deacetylase recruitment and RARα blockade in the pathogenesis of acute promyelocytic leukemia

2006 ◽  
Vol 203 (4) ◽  
pp. 821-828 ◽  
Author(s):  
Hiromichi Matsushita ◽  
Pier Paolo Scaglioni ◽  
Mantu Bhaumik ◽  
Eduardo M. Rego ◽  
Lu Fan Cai ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Fusion Protein ◽  
Acute Promyelocytic Leukemia ◽  
Histone Deacetylases ◽  
Retinoic Acid Receptor ◽  
Promyelocytic Leukemia ◽  
Dominant Negative

The promyelocytic leukemia–retinoic acid receptor α (PML-RARα) protein of acute promyelocytic leukemia (APL) is oncogenic in vivo. It has been hypothesized that the ability of PML-RARα to inhibit RARα function through PML-dependent aberrant recruitment of histone deacetylases (HDACs) and chromatin remodeling is the key initiating event for leukemogenesis. To elucidate the role of HDAC in this process, we have generated HDAC1–RARα fusion proteins and tested their activity and oncogenicity in vitro and in vivo in transgenic mice (TM). In parallel, we studied the in vivo leukemogenic potential of dominant negative (DN) and truncated RARα mutants, as well as that of PML-RARα mutants that are insensitive to retinoic acid. Surprisingly, although HDAC1-RARα did act as a bona fide DN RARα mutant in cellular in vitro and in cell culture, this fusion protein, as well as other DN RARα mutants, did not cause a block in myeloid differentiation in vivo in TM and were not leukemogenic. Comparative analysis of these TM and of TM/PML−/− and p53−/− compound mutants lends support to a model by which the RARα and PML blockade is necessary, but not sufficient, for leukemogenesis and the PML domain of the fusion protein provides unique functions that are required for leukemia initiation.

scholarly journals Regulation of the expression of annexin VIII in acute promyelocytic leukemia

Blood ◽  
1994 ◽  
Vol 84 (1) ◽  
pp. 279-286 ◽  
Author(s):  
A Sarkar ◽  
P Yang ◽  
YH Fan ◽  
ZM Mu ◽  
R Hauptmann ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Acute Promyelocytic Leukemia ◽  
Cellular Localization ◽  
Signal Transduction Pathway ◽  
Promyelocytic Leukemia ◽  
Induced Differentiation ◽  
Acute Leukemias ◽  
Nb4 Cells

Annexin VIII is a calcium-dependent phospholipid-binding protein previously identified as a blood anticoagulant based on in vitro studies. However, the physiologic function of annexin VIII remains unknown. In acute promyelocytic leukemia (APL) the annexin VIII gene is highly expressed, but its expression is undetectable in the blasts of other acute leukemias. In the present investigation, we showed using the APL-derived NB4 cell line that expression of the annexin VIII gene is regulated at the transcription level during induced differentiation by all-trans retinoic acid (ATRA). The half-life of the annexin VIII mRNA is about 5 to 6 hours, as determined by using actinomycin D as a transcription inhibitor. Analysis of the expression of annexin VIII protein in NB4 cells and in APL samples showed a consistent expression of a predominant 36-kD protein and a weak 72-kD protein. After ATRA- induced differentiation of NB4 cells, the annexin VIII protein level reduced gradually, but a detectable level persisted even after 4 days of induction. Because annexin VIII mRNA becomes undetectable after 48 hours of ATRA induction, this result indicates that annexin VIII is a relatively stable protein. A multiple tissue Northern blot analysis was performed, and we found that annexin VIII is normally expressed in the placenta and the lung. Cellular localization of the annexin VIII protein was determined by immunofluorescence staining and subcellular fractionation. These results indicated that annexin VIII is predominantly localized to the plasma membrane. The annexin VIII is neither an extracellular protein nor associated with the cell surface suggesting that it does not play a role in blood coagulation in vivo. The plasma membrane localization and its property as a phospholipase inhibitor suggests that annexin VIII may have a role in the signal transduction pathway in the APL cells.

scholarly journals Regulation of the expression of annexin VIII in acute promyelocytic leukemia

Blood ◽  
1994 ◽  
Vol 84 (1) ◽  
pp. 279-286 ◽  
Author(s):  
A Sarkar ◽  
P Yang ◽  
YH Fan ◽  
ZM Mu ◽  
R Hauptmann ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Acute Promyelocytic Leukemia ◽  
Cellular Localization ◽  
Signal Transduction Pathway ◽  
Promyelocytic Leukemia ◽  
Induced Differentiation ◽  
Acute Leukemias ◽  
Nb4 Cells

Abstract Annexin VIII is a calcium-dependent phospholipid-binding protein previously identified as a blood anticoagulant based on in vitro studies. However, the physiologic function of annexin VIII remains unknown. In acute promyelocytic leukemia (APL) the annexin VIII gene is highly expressed, but its expression is undetectable in the blasts of other acute leukemias. In the present investigation, we showed using the APL-derived NB4 cell line that expression of the annexin VIII gene is regulated at the transcription level during induced differentiation by all-trans retinoic acid (ATRA). The half-life of the annexin VIII mRNA is about 5 to 6 hours, as determined by using actinomycin D as a transcription inhibitor. Analysis of the expression of annexin VIII protein in NB4 cells and in APL samples showed a consistent expression of a predominant 36-kD protein and a weak 72-kD protein. After ATRA- induced differentiation of NB4 cells, the annexin VIII protein level reduced gradually, but a detectable level persisted even after 4 days of induction. Because annexin VIII mRNA becomes undetectable after 48 hours of ATRA induction, this result indicates that annexin VIII is a relatively stable protein. A multiple tissue Northern blot analysis was performed, and we found that annexin VIII is normally expressed in the placenta and the lung. Cellular localization of the annexin VIII protein was determined by immunofluorescence staining and subcellular fractionation. These results indicated that annexin VIII is predominantly localized to the plasma membrane. The annexin VIII is neither an extracellular protein nor associated with the cell surface suggesting that it does not play a role in blood coagulation in vivo. The plasma membrane localization and its property as a phospholipase inhibitor suggests that annexin VIII may have a role in the signal transduction pathway in the APL cells.

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