Bcr3 PML-RARA: short fusion, small blasts!
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ABSTRACT:
SUBMITTER: Takeda MR
PROVIDER: S-EPMC9635526 | biostudies-literature | 2021 May
REPOSITORIES: biostudies-literature
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Project description:Because PML-RARA-induced acute promyelocytic leukemia (APL) is a morphologically differentiated leukemia, many groups have speculated about whether its leukemic cell of origin is a committed myeloid precursor (e.g. a promyelocyte) versus an hematopoietic stem/progenitor cell (HSPC). We originally targeted PML-RARA expression with CTSG regulatory elements, based on the early observation that this gene was maximally expressed in cells with promyelocyte morphology. Here, we show that both Ctsg, and PML-RARA targeted to the Ctsg locus (in Ctsg-PML-RARA mice), are expressed in the purified KLS cells of these mice (KLS = Kit(+)Lin(-)Sca(+), which are highly enriched for HSPCs), and this expression results in biological effects in multi-lineage competitive repopulation assays. Further, we demonstrate the transcriptional consequences of PML-RARA expression in Ctsg-PML-RARA mice in early myeloid development in other myeloid progenitor compartments [common myeloid progenitors (CMPs) and granulocyte/monocyte progenitors (GMPs)], which have a distinct gene expression signature compared to wild-type (WT) mice. Although PML-RARA is indeed expressed at high levels in the promyelocytes of Ctsg-PML-RARA mice and alters the transcriptional signature of these cells, it does not induce their self-renewal. In sum, these results demonstrate that in the Ctsg-PML-RARA mouse model of APL, PML-RARA is expressed in and affects the function of multipotent progenitor cells. Finally, since PML/Pml is normally expressed in the HSPCs of both humans and mice, and since some human APL samples contain TCR rearrangements and express T lineage genes, we suggest that the very early hematopoietic expression of PML-RARA in this mouse model may closely mimic the physiologic expression pattern of PML-RARA in human APL patients.
| S-EPMC3466302 | biostudies-literature
Project description:Although acute promyelocytic leukemia (APL) is one of the most characterized forms of acute myeloid leukemia (AML), the molecular mechanisms involved in the development and progression of this disease are still a matter of study. APL is defined by the PML-RARA rearrangement as a consequence of the translocation t(15;17)(q24;q21). However, this abnormality alone is not able to trigger the whole leukemic phenotype and secondary cooperating events might contribute to APL pathogenesis. Additional somatic mutations are known to occur recurrently in several genes, such as FLT3, WT1, NRAS and KRAS, whereas mutations in other common AML genes are rarely detected, resulting in a different molecular profile compared to other AML subtypes. How this mutational spectrum, including point mutations in the PML-RARA fusion gene, could contribute to the 10%-15% of relapsed or resistant APL patients is still unknown. Moreover, due to the uncertain impact of additional mutations on prognosis, the identification of the APL-specific genetic lesion is still the only method recommended in the routine evaluation/screening at diagnosis and for minimal residual disease (MRD) assessment. However, the gene expression profile of genes, such as ID1, BAALC, ERG, and KMT2E, once combined with the molecular events, might improve future prognostic models, allowing us to predict clinical outcomes and to categorize APL patients in different risk subsets, as recently reported. In this review, we will focus on the molecular characterization of APL patients at diagnosis, relapse and resistance, in both children and adults. We will also describe different standardized molecular approaches to study MRD, including those recently developed. Finally, we will discuss how novel molecular findings can improve the management of this disease.
| S-EPMC7139833 | biostudies-literature
Project description: Not available
| S-EPMC5359182 | biostudies-literature
Project description:The prognosis of AML patients with adverse genetics, such as a complex, monosomal karyotype and TP53 lesions, is still dismal even with standard chemotherapy. DNA-hypomethylating agent monotherapy induces an encouraging response rate in these patients. When combined with decitabine (DAC), all-trans retinoic acid (ATRA) resulted in an improved response rate and longer overall survival in a randomized phase II trial (DECIDER; NCT00867672). The molecular mechanisms governing this in vivo synergism are unclear. We now demonstrate cooperative antileukemic effects of DAC and ATRA on AML cell lines U937 and MOLM-13. By RNA-sequencing, derepression of >1200 commonly regulated transcripts following the dual treatment was observed. Overall chromatin accessibility (interrogated by ATAC-seq) and, in particular, at motifs of retinoic acid response elements were affected by both single-agent DAC and ATRA, and enhanced by the dual treatment. Cooperativity regarding transcriptional induction and chromatin remodeling was demonstrated by interrogating the HIC1, CYP26A1, GBP4, and LYZ genes, in vivo gene derepression by expression studies on peripheral blood blasts from AML patients receiving DAC + ATRA. The two drugs also cooperated in derepression of transposable elements, more effectively in U937 (mutated TP53) than MOLM-13 (intact TP53), resulting in a "viral mimicry" response. In conclusion, we demonstrate that in vitro and in vivo, the antileukemic and gene-derepressive epigenetic activity of DAC is enhanced by ATRA.
| S-EPMC9395383 | biostudies-literature
Project description:The ubiquitin-like SUMO proteins covalently modify protein substrates and regulate their functional properties. In a broad spectrum of cancers, the tumor suppressor PML undergoes ubiquitin-mediated degradation primed by CK2 phosphorylation. Here, we report that the SUMO E3-ligase inhibitor PIAS1 regulates oncogenic signaling through its ability to sumoylate PML and the PML-RARA oncoprotein of acute promyelocytic leukemia (APL). PIAS1-mediated SUMOylation of PML promoted CK2 interaction and ubiquitin/proteasome-mediated degradation of PML, attenuating its tumor suppressor functions. In addition, PIAS1-mediated SUMOylation of PML-RARA was essential for induction of its degradation by arsenic trioxide, an effective APL treatment. Moreover, PIAS1 suppression abrogated the ability of arsenic trioxide to trigger apoptosis in APL cells. Lastly, PIAS1 was also essential for PML degradation in non-small cell lung carcinoma (NSCLC) cells, and PML and PIAS1 were inversely correlated in NSCLC cell lines and primary specimens. Together, our findings reveal novel roles for PIAS1 and the SUMOylation machinery in regulating oncogenic networks and the response to leukemia therapy.
| S-EPMC3342450 | biostudies-literature
Project description:Loss of function mutations in the DNA methyltransferase DNMT3A are highly recurrent in acute myeloid leukemia (AML). DNMT3A and DNMT3B encode the two methyltransferases that are primarily responsible for the de novo methylation of specific DNA sequences during cellular differentiation. DNMT3A mutations are rarely found in AML patients with translocations that create oncogenic fusion genes (e.g. PML-RARA, RUNX1-RUNX1T1, CBFB-MYH11, and MLL-X). To begin to define the reasons why these mutations do not occur together, we used retroviral vectors to express PML-RARA, RUNX1-RUNX1T1, and MLL-AF9 in the bone marrow cells of wild type (WT) or Dnmt3a deficient mice; we also examined the hematopoietic phenotypes of Ctsg-PML-RARA animals (which express PML-RARA in early hematopoietic progenitors and myeloid precursors) with and without Dnmt3a. We demonstrated that the methyltransferase activity of Dnmt3a (but not Dnmt3b) is required for aberrant self-renewal ex vivo that is driven by PML-RARA (but not RUNX1-RUNX1T1 or MLL-AF9); furthermore, the PML-RARA-driven competitive transplantation advantage and leukemia generation both required Dnmt3a. Together, these findings demonstrate that PML-RARA is specifically dependent on Dnmt3a to initiate APL in mice, and may explain why loss-of-function DNMT3A mutations are not found in patients with acute promyelocytic leukemia.
2015-10-01 | GSE68844 | GEO
Project description:The DNA methyltransferases DNMT3A and DNMT3B are primarily responsible for de novo methylation of specific cytosine residues in CpG dinucleotides during mammalian development. While loss-of-function mutations in DNMT3A are highly recurrent in acute myeloid leukemia (AML), DNMT3A mutations are almost never found in AML patients with translocations that create oncogenic fusion genes such as PML-RARA, RUNX1-RUNX1T1, and MLL-AF9. Here, we explored how DNMT3A is involved in the function of these fusion genes. We used retroviral vectors to express PML-RARA, RUNX1-RUNX1T1, or MLL-AF9 in bone marrow cells derived from WT or DNMT3A-deficient mice. Additionally, we examined the phenotypes of hematopoietic cells from Ctsg-PML-RARA mice, which express PML-RARA in early hematopoietic progenitors and myeloid precursors, with or without DNMT3A. We determined that the methyltransferase activity of DNMT3A, but not DNMT3B, is required for aberrant PML-RARA-driven self-renewal ex vivo and that DNMT3A is dispensable for RUNX1-RUNX1T1- and MLL-AF9-driven self-renewal. Furthermore, both the PML-RARA-driven competitive transplantation advantage and development of acute promyelocytic leukemia (APL) required DNMT3A. Together, these findings suggest that PML-RARA requires DNMT3A to initiate APL in mice.
| S-EPMC4701540 | biostudies-literature
Project description:Acute promyelocytic leukemia (APL) is highly aggressive and is frequently associated with disseminated intravascular coagulation and high early death rates. Although all-trans retinoic acid (RA) induces complete remission in a high proportion of patients with APL, there are limited treatments for APL patients with RA resistance. Here we report an atypical APL patient, with an APL-like disease that developed very slowly without anti-leukemia therapy for nearly 2 years. During that time, the patient only intermittently received anti-HBV drugs, i.e., the combination of adefovir dipivoxil (ADV) and entecavir (ETV), leading us to hypothesize that ADV and/or ETV could inhibit APL progression. Our results showed that anti-HBV drugs ADV and ETV both exhibited significantly inhibitory effects on APL cells, and ADV indicated a much greater cytotoxic effect than ETV on APL cells. We further found that ADV significantly promoted APL cell differentiation and apoptosis, thereby restraining the progression of APL. Most importantly, our study uncovered a novel mechanism of ADV prohibiting APL progression, which was mediated, at least in part, by inhibition of TRIB3 and degradation of the oncoprotein PML-RARA, therefore leading to APL cell differentiation and apoptosis. Taken together, our study demonstrated that ADV, an anti-HBV drug, had significantly inhibitory effects on APL, and provided a novel therapeutic strategy for APL patients with RA resistance. Supplementary Information The online version contains supplementary material available at 10.1186/s40164-022-00355-1.
| S-EPMC9676767 | biostudies-literature
Project description:PML Nuclear Bodies (NBs) are disrupted in PML-RARA-driven acute promyelocytic leukemia (APL). Arsenic trioxide (ATO) cures 70% APL patients, driving PML-RARA degradation and NB reformation. In non-APL cells, arsenic binding onto PML also amplifies NB formation. Yet, the actual molecular mechanism(s) involved remain(s) elusive. Here, we establish that PML NBs display some features of liquid-liquid phase separation and that ATO induces a gel-like transition. PML B-box-2 structure reveals an alpha helix driving B2 trimerization and positioning a cysteine trio to form an ideal arsenic-binding pocket. Altering either of the latter impedes ATO-driven NB-assembly, PML sumoylation and PML-RARA degradation, mechanistically explaining clinical ATO-resistance. This B2 trimer and the C213 trio create an oxidation-sensitive rheostat that controls PML NB assembly dynamics and downstream signaling in both basal state and during stress response. These findings identify the structural basis for arsenic targeting of PML which could pave the way to novel cancer drugs.
| S-EPMC10714139 | biostudies-literature
Project description:PML/RARA is the oncoprotein driving acute promyelocytic leukemia (APL). It suppresses genes expression by recruitment of a number of transcriptional repressors, resulting in differentiation block and malignant transformation of hematopoietic cells. Here, we found that mice primary hematopoietic progenitor cells (HPCs), transduced by DNA-binding-defective PML/RARA mutants, were deficient in colony formation. Further experiments showed that DNA-binding-defective PML/RARA mutants could not repress the transcription of retinoic acid regulated genes. Intriguingly, there were no significant differences of the micro-speckled intracellular distribution between the mutants and wild-type PML/RARA. Some retinoic acid target genes regulated by PML/RARA are involved in not only differentiation block but also hematopoietic cell self-renewal. Altogether, our data demonstrate that direct DNA-binding is essential for PML/RARA to immortalize hematopoietic cells, while disruption of PML-nuclear body does not seem to be a prerequisite for hematopoietic cell transformation.
| S-EPMC4131979 | biostudies-literature