Acute myeloid leukemia with the 8q22;21q22 translocation: secondary mutational events and alternative t(8;21) transcripts

Abstract Nonrandom and somatically acquired chromosomal translocations can be identified in nearly 50% of human acute myeloid leukemias. One common chromosomal translocation in this disease is the 8q22;21q22 translocation. It involves the AML1 (RUNX1) gene on chromosome 21 and the ETO (MTG8, RUNX1T1) gene on chromosome 8 generating the AML1-ETO fusion proteins. In this review, we survey recent advances made involving secondary mutational events and alternative t(8;21) transcripts in relation to understanding AML1-ETO leukemogenesis.

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Translocation breakpoints are clustered on both chromosome 8 and chromosome 21 in the t(8;21) of acute myeloid leukemia

Blood ◽

10.1182/blood.v81.3.592.592 ◽

1993 ◽

Vol 81 (3) ◽

pp. 592-596 ◽

Cited By ~ 22

Author(s):

JE Tighe ◽

A Daga ◽

F Calabi

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Chromosome 8 ◽

Chromosome 21 ◽

Novel Gene ◽

Translocation Breakpoints ◽

Acute Myeloid

Abstract The t(8;21)(q22;q22) is consistently associated with acute myeloid leukemia (AML) M2. Recent data have suggested that breakpoints on chromosome 21 are clustered within a single intron of a novel gene, AML1, just downstream of a region of homology to the runt gene of D melanogaster. In this report, we confirm rearrangement at the same location in at least 12 of 18 patients with t(8;21). Furthermore, we have isolated recombinant clones spanning the breakpoint regions on both the der(8) and the der(21) from one patient. By using a chromosome 8 probe derived from these clones, we show that t(8;21) breakpoints are also clustered on chromosome 8.

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RUNX1/AML1 DNA Binding Domain and ETO/MTG8 NHR2 Dimerization Domain Are Critical to AML1−ETO9a Leukemogenesis.

Blood ◽

10.1182/blood.v108.11.772.772 ◽

2006 ◽

Vol 108 (11) ◽

pp. 772-772

Author(s):

Ming Yan ◽

Scott Hiebert ◽

Dong-Er Zhang

Keyword(s):

Acute Myeloid Leukemia ◽

Dna Binding ◽

Median Survival ◽

Myeloid Leukemia ◽

Binding Domain ◽

Chromosome 8 ◽

Chromosome 21 ◽

Dna Binding Domain ◽

Dimerization Domain ◽

Acute Myeloid

Abstract The 8;21 translocation, which involves the gene encoding the RUNX family DNA binding transcription factor AML1 (RUNX1) on chromosome 21 and the ETO (MTG8) gene on chromosome 8, generates AML1−ETO fusion proteins. Previous analyses have demonstrated that full length AML1−ETO blocks AML1 function and requires additional mutagenic events to promote leukemia in mice. More recently, we have identified an alternatively spliced form of AML1−ETO, AML1−ETO9a, from t(8;21) AML patient samples (Yan et al. Nat. Med.12:945–949, 2006). AML1−ETO9a lacks the C−terminal NHR3 and NHR4 domains of AML1−ETO and is highly leukemogenic in mice. Here, we report that the AML1 DNA binding domain and the ETO NHR2 dimerization domain, but not the ETO NHR1 domain are critical for the induction of acute myeloid leukemia by AML1−ETO9a. Using retroviral mediated gene expression and hematopoietic cell transplantation in recipient mice, we examined AML1−ETO9a, AML1−ETO9a without the NHR1 domain [AML1−ETO9a (dNHR1)] or the NHR2 domain [AML1−ETO9a(dNHR2)], without a histone deacetylase/Sin3A interacting domain between NHR1 and NHR2 [AML1−ETO9a(d350–428)], and mutant AML1−ETO9a proteins that have lost the capacity to bind DNA [AML1−ETO9a(L148D)] and [AML1−ETO9a(R173Q)] in leukemogenesis. All of the mice transplanted with AML1−ETO9a (n =11) and AML1−ETO9a(dNHR1) (n = 12) expressing cells developed acute myeloid leukemia with a similar phenotype (Lin−/c−kit+) within 21 weeks. The median survival times of mice with AML1−ETO9a and AML1−ETO9a(dNHR1) are 9.4 weeks and 10.5 weeks, respectively. Furthermore, all of the mice expressing AML1−ETO9a(d350–428) (n = 11) also developed leukemia with a median survival time of 17.2 weeks. Significant numbers of AML1−ETO9a(d350–428) expressing cells are positive for myeloid markers CD11b and Gr1 in these leukemic mice. In contrast, none of the mice with AML1−ETO9a(dNHR2) (n = 14), AML1−ETO9a(L148D) (n = 8), and AML1−ETO9a(R173Q) (n = 8) expressing hematopoietic cells developed leukemia. Taken together, these data suggest that the AML1 DNA binding domain and the ETO NHR2 domain are required for AML1−ETO9a induced leukemia development and the region between amino acids 350 and 428 of AML1−ETO9a also affects the differentiation stage and latency of leukemogenesis.

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Translocation breakpoints are clustered on both chromosome 8 and chromosome 21 in the t(8;21) of acute myeloid leukemia

Blood ◽

10.1182/blood.v81.3.592.bloodjournal813592 ◽

1993 ◽

Vol 81 (3) ◽

pp. 592-596 ◽

Cited By ~ 3

Author(s):

JE Tighe ◽

A Daga ◽

F Calabi

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Chromosome 8 ◽

Chromosome 21 ◽

Novel Gene ◽

Translocation Breakpoints ◽

Acute Myeloid

The t(8;21)(q22;q22) is consistently associated with acute myeloid leukemia (AML) M2. Recent data have suggested that breakpoints on chromosome 21 are clustered within a single intron of a novel gene, AML1, just downstream of a region of homology to the runt gene of D melanogaster. In this report, we confirm rearrangement at the same location in at least 12 of 18 patients with t(8;21). Furthermore, we have isolated recombinant clones spanning the breakpoint regions on both the der(8) and the der(21) from one patient. By using a chromosome 8 probe derived from these clones, we show that t(8;21) breakpoints are also clustered on chromosome 8.

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Roles of Histone Deacetylases in Acute Myeloid Leukemia With Fusion Proteins

Frontiers in Oncology ◽

10.3389/fonc.2021.741746 ◽

2021 ◽

Vol 11 ◽

Author(s):

Juan Zhang ◽

Xuefeng Gao ◽

Li Yu

Keyword(s):

Acute Myeloid Leukemia ◽

Cell Fate ◽

Histone Deacetylases ◽

Fusion Proteins ◽

Myeloid Leukemia ◽

Current Knowledge ◽

Chromosomal Rearrangements ◽

Chromosomal Translocation ◽

Transcriptional Switch ◽

Acute Myeloid

Accurate orchestration of gene expression is critical for the process of normal hematopoiesis, and dysregulation is closely associated with leukemogenesis. Epigenetic aberration is one of the major causes contributing to acute myeloid leukemia (AML), where chromosomal rearrangements are frequently found. Increasing evidences have shown the pivotal roles of histone deacetylases (HDACs) in chromatin remodeling, which are involved in stemness maintenance, cell fate determination, proliferation and differentiation, via mastering the transcriptional switch of key genes. In abnormal, these functions can be bloomed to elicit carcinogenesis. Presently, HDAC family members are appealing targets for drug exploration, many of which have been deployed to the AML treatment. As the majority of AML events are associated with chromosomal translocation resulting in oncogenic fusion proteins, it is valuable to comprehensively understand the mutual interactions between HDACs and oncogenic proteins. Therefore, we reviewed the process of leukemogenesis and roles of HDAC members acting in this progress, providing an insight for the target anchoring, investigation of hyperacetylated-agents, and how the current knowledge could be applied in AML treatment.

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Persistence of the 8;21 translocation in patients with acute myeloid leukemia type M2 in long-term remission

Blood ◽

10.1182/blood.v82.3.712.bloodjournal823712 ◽

1993 ◽

Vol 82 (3) ◽

pp. 712-715 ◽

Cited By ~ 1

Author(s):

G Nucifora ◽

RA Larson ◽

JD Rowley

Keyword(s):

Acute Myeloid Leukemia ◽

Complete Remission ◽

Myeloid Leukemia ◽

Fusion Gene ◽

Fusion Transcript ◽

Chromosome 8 ◽

Chromosome 21 ◽

First Relapse ◽

Acute Myeloid

The translocation between chromosomes 8 and 21, t(8;21) (q22;q22), is the most frequent abnormality in acute myeloid leukemia (AML) with French-American-British type M2 (FAB-M2) morphology. The breakpoints in this translocation have been characterized at the molecular level, and the genes involved are AML1 on chromosome 21 and ETO on chromosome 8. The rearrangement of the two chromosomes results in a fusion gene and in the production of a consistent fusion transcript on the der(8) chromosome. We have used oligonucleotide primers derived from both sides of the fusion cDNA junction and reverse transcription-polymerase chain reaction (RT-PCR) to analyze six AML-M2 patients with a t(8;21) during various stages of their disease. Two patients studied at diagnosis and one studied at first relapse are alive off therapy and in continuous complete remission for 83 to 94 months. We have detected the AML/ETO fusion transcript in recent peripheral blood samples from each of them. Three other patients also had a fusion transcript detected after 1 to 4 months in remission. Two of these patients subsequently relapsed and died whereas the third patient is alive and in continuous complete remission 70 months later. Thus, our preliminary data suggest that cells with the translocation are still circulating in t(8;21) patients in long-term remission. This finding raises serious questions regarding the interpretation of positive results obtained only with this technique that may not be suitable to decide appropriate further treatment for patients in clinical remission.

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Heterogeneous Chromosomal Mechanisms Generating the 5′RUNX1/3′CBFA2T1 Gene in Acute Myeloid Leukemia.

Blood ◽

10.1182/blood.v104.11.4272.4272 ◽

2004 ◽

Vol 104 (11) ◽

pp. 4272-4272

Author(s):

Giorgina Specchia ◽

Francesco Albano ◽

Luisa Anelli ◽

Antonella Zagaria ◽

Arcangelo Liso ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Fusion Gene ◽

Chromosome 8 ◽

Chromosome 21 ◽

Derivative Chromosome ◽

Molecular Cytogenetic ◽

Karyotypic Abnormality ◽

Fusion Signal ◽

Acute Myeloid

Abstract Translocation t(8;21)(q22;q22) is a common karyotypic abnormality detected in about 15% of Acute Myeloid Leukemia (AML) cases. The rearrangement results in fusion of the RUNX1 (also known as AML1) and CBFA2T1 (also known as ETO) genes generating a 5′RUNX1/3′CBFA2T1 transcriptionally active fusion gene on derivative chromosome 8. In 1 to 8.5% of AML cases insertions events generating a 5′RUNX1/3′CBFA2T1 fusion gene have been reported, whereas the occurrence of inversions accompanying the t(8;21) has never been observed. We report a screening of 82 AML cases bearing the RUNX1/CBFA2T1 rearrangement detected by RT-PCR; all cases were tested by Fluorescence In Situ Hybridization (FISH) with BAC and PAC clones specific for CBFA2T1 and RUNX1 genes. This analysis allowed us to reveal five cases with ins(21;8), one with ins(8;21), and two with a pericentric chromosome 8 inversion followed by a t(8;21) translocation. A detailed molecular cytogenetic characterization of breakpoints has been performed in all cases. FISH co-hybridization experiments with CBFA2T1 and RUNX1 probes revealed the presence of a functional fusion gene on the der(21) instead of the der(8) chromosome in five cases with ins(21;8); a single fusion signal on the der(8) chromosome was detected in the case with ins(8;21). The use of the same clones in FISH studies showed the presence of a single unexpected fusion signal on the 8p derivative chromosome in addition to faint CBFA2T1 and RUNX1 signals on the long arm of der(8) and der(21) chromosomes, respectively. These results suggested that a pericentric chromosome 8 inversion involving CBFA2T1 gene occurred and that the chromosome 21 was rearranged with the 8p derivative chromosome. Appropriate chromosome 21 and 8 BAC clones were employed to precisely define the size of inserted regions in cases with insertions and the breakpoint on the 8p derivative chromosome in cases showing pericentric chromosome 8 inversion. The insertion size turned out to be very heterogeneous, ranging from a minimum of 2.4 Mb to a maximum of 44 Mb. In both cases with chromosome 8 inversion, the CBFA2T1 gene represents the breakpoint at the chromosome 8 long arm whereas the 8p breakpoint showed different mapping positions in 8p21.3 and 8p21.1, respectively. Our results illustrate that (1) heterogeneous mechanisms can lead to the generation of the 5′RUNX1/3′CBFA2T1 chimeric gene; (2) molecular cytogenetic techniques may identify cryptic chromosomal changes, not detected by conventional cytogenetic analysis; (3) the crucial role of the 5′RUNX1/3′CBFA2T1 fusion gene in leukemogenesis does not depend on its location.

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Persistence of the 8;21 translocation in patients with acute myeloid leukemia type M2 in long-term remission

Blood ◽

10.1182/blood.v82.3.712.712 ◽

1993 ◽

Vol 82 (3) ◽

pp. 712-715 ◽

Cited By ~ 196

Author(s):

G Nucifora ◽

RA Larson ◽

JD Rowley

Keyword(s):

Acute Myeloid Leukemia ◽

Complete Remission ◽

Myeloid Leukemia ◽

Fusion Gene ◽

Fusion Transcript ◽

Chromosome 8 ◽

Chromosome 21 ◽

First Relapse ◽

Acute Myeloid

Abstract The translocation between chromosomes 8 and 21, t(8;21) (q22;q22), is the most frequent abnormality in acute myeloid leukemia (AML) with French-American-British type M2 (FAB-M2) morphology. The breakpoints in this translocation have been characterized at the molecular level, and the genes involved are AML1 on chromosome 21 and ETO on chromosome 8. The rearrangement of the two chromosomes results in a fusion gene and in the production of a consistent fusion transcript on the der(8) chromosome. We have used oligonucleotide primers derived from both sides of the fusion cDNA junction and reverse transcription-polymerase chain reaction (RT-PCR) to analyze six AML-M2 patients with a t(8;21) during various stages of their disease. Two patients studied at diagnosis and one studied at first relapse are alive off therapy and in continuous complete remission for 83 to 94 months. We have detected the AML/ETO fusion transcript in recent peripheral blood samples from each of them. Three other patients also had a fusion transcript detected after 1 to 4 months in remission. Two of these patients subsequently relapsed and died whereas the third patient is alive and in continuous complete remission 70 months later. Thus, our preliminary data suggest that cells with the translocation are still circulating in t(8;21) patients in long-term remission. This finding raises serious questions regarding the interpretation of positive results obtained only with this technique that may not be suitable to decide appropriate further treatment for patients in clinical remission.

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Alternative, out-of-frame runt/MTG8 transcripts are encoded by the derivative (8) chromosome in the t(8;21) of acute myeloid leukemia M2

Blood ◽

10.1182/blood.v84.7.2115.2115 ◽

1994 ◽

Vol 84 (7) ◽

pp. 2115-2121 ◽

Cited By ~ 21

Author(s):

JE Tighe ◽

F Calabi

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Chromosome 8 ◽

Chromosome 21 ◽

Alternative Transcripts ◽

Cluster Region ◽

Conserved Domain ◽

Physical Linkage ◽

Per Se ◽

Acute Myeloid

Abstract In the t(8;21) of acute myeloid leukemia (AML) M2, breakpoints are clustered on both chromosomes. The chromosome 21 breakpoint cluster region (bcr) falls within the runt locus, in the intron immediately downstream of the exons encoding an evolutionary conserved domain (the runt box). Transcripts in which the runt box is fused in frame to a novel sequence derived from chromosome 8 (MTG8) have been previously identified and have been assumed to constitute a critical leukemogenic event. Here we show physical linkage of the chromosome 8 bcr to the MTG8 locus. Unexpectedly, not only does the bcr map upstream of the most 5′ MTG8 exon found in runt/MTG8 fusion transcripts, but it also maps upstream of a further 5′ exon. In addition, we demonstrate the presence of alternative transcripts, originating from the der(8) chromosome, in which runt is out of frame with MTG8. Thus, runt truncation per se, rather than its fusion to MTG8, may be the crucial leukemogenic event.

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Detection of DNA rearrangements in the AML1 and ETO loci and of an AML1/ETO fusion mRNA in patients with t(8;21) acute myeloid leukemia

Blood ◽

10.1182/blood.v81.4.883.883 ◽

1993 ◽

Vol 81 (4) ◽

pp. 883-888 ◽

Cited By ~ 139

Author(s):

G Nucifora ◽

DJ Birn ◽

P Erickson ◽

J Gao ◽

MM LeBeau ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Cell Line ◽

Southern Blot ◽

Myeloid Leukemia ◽

Dna Probes ◽

Response To Therapy ◽

Chromosome 8 ◽

Chromosome 21 ◽

Breakpoint Junction ◽

Acute Myeloid

Abstract The (8;21)(q22;q22) translocation is a frequent karyotypic abnormality seen in approximately 40% of patients with acute myeloid leukemia subtype M2 (AML-M2) and an abnormal karyotype. The translocation interrupts two genes, AML1 on chromosome 21 and ETO on chromosome 8, that are consequently fused in the der(8) chromosome to produce a novel chimeric gene and message. Selected genomic DNA probes from chromosome 21 and from chromosome 8 near the breakpoint junction detect rearrangements in the DNA of about 80% of the patients with the rearrangement at diagnosis and in relapse. We analyzed the DNA of 20 patients with t(8;21) AML by standard Southern blot with probes originating from chromosomes 21 and 8 near the breakpoint junction, and we identified rearranged bands in 17 of the 20 patients at diagnosis and in relapse. We also used the polymerase chain reaction (PCR) with appropriate primers from the AML1 and ETO genes to amplify the cDNAs from a cell line with the t(8;21) and from seven AML patients with the t(8;21). We detected a fused transcript in the cell line and in all of the patients analyzed, including three patients who did not show any rearrangement by Southern blot analysis and one patient in hematologic remission, who later relapsed. Combining the results from Southern blot and PCR analysis, we could detect the t(8;21) in all of the patients tested. These results indicate that, whereas several DNA probes used as genetic markers do detect the t(8;21) in most, but not all Southern blots of patients with AML, PCR amplification with primers from AML1 and ETO can be used as a more sensitive and accurate means for detecting this chromosomal abnormality, and for observing the patients' response to therapy.

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A leukemia fusion protein attenuates the spindle checkpoint and promotes aneuploidy

Blood ◽

10.1182/blood-2006-09-045583 ◽

2006 ◽

Vol 109 (9) ◽

pp. 3963-3971 ◽

Cited By ~ 21

Author(s):

Anita Boyapati ◽

Ming Yan ◽

Luke F. Peterson ◽

Joseph R. Biggs ◽

Michelle M. Le Beau ◽

...

Keyword(s):

Acute Myeloid Leukemia ◽

Myeloid Leukemia ◽

Spindle Checkpoint ◽

Chromosomal Translocation ◽

Leukemia Cells ◽

Mouse Leukemia ◽

Checkpoint Proteins ◽

Runx1 Gene ◽

Primary Leukemia ◽

Acute Myeloid

Abstract The 8;21 chromosomal translocation occurs in 15% to 40% of patients with the FAB M2 subtype of acute myeloid leukemia (AML). This chromosomal abnormality fuses part of the AML1/RUNX1 gene to the ETO/MTG8 gene and generates the AML1-ETO protein. We previously identified a C-terminal truncated AML1-ETO protein (AEtr) in a mouse leukemia model. AEtr is almost identical to the AML1-ETO exon 9a isoform expressed in leukemia patients. Here, we describe a novel function of AEtr in the development of aneuploidy through spindle checkpoint attenuation. AEtr cells had a reduced mitotic index following nocodazole treatment, suggesting a failure in a subset of cells to arrest in mitosis with a functional spindle checkpoint. Additionally, primary leukemia cells and cell lines expressing AEtr were aneuploid. Moreover, AEtr cells had reduced levels of several spindle checkpoint proteins including BubR1 and securin following treatment with the spindle poison nocodazole. These results suggest that inactivation of the spindle checkpoint may contribute to the development of aneuploidy described in t(8;21) leukemia patients.

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