Jumping translocation in acute monocytic leukemia (M5b) with alternative breakpoint sites in the long arm of donor chromosome 3

Jumping translocations: Short telomeres or pathogenic TP53 variants as underlying mechanism in acute myeloid leukemia and myelodysplastic syndrome?

Chromosomal rearrangements involving one donor chromosome and two or more recipient chromosomes are called jumping translocations. To date only few cases of acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) with jumping translocations have been described and the underlying mechanisms remain unclear. Here, we analyzed 11 AML and 5 MDS cases with jumping translocations. The cases were analyzed by karyotyping, FISH, telomere length measurement, and next-generation sequencing with an AML/MDS gene panel. Cases with jumping translocations showed significantly (P < .01) shorter telomeres in comparison to healthy age-matched controls. Additional neo-telomeres were found in two cases. In total, eight cases showed recipient chromosomes with a breakpoint in the centromeric region all of them harboring a pathogenic variant in the TP53 gene (n = 6) and/or a loss of TP53 (n = 5). By contrast, no pathogenic variant or loss of TP53 was identified in the six cases showing recipient chromosomes with a breakpoint in the telomeric region. In conclusion, our results divide the cohort of AML and MDS cases with jumping translocations into two groups: the first group with a telomeric breakpoint of the recipient chromosome is characterized by short telomeres and a possibly telomere-based mechanism of chromosomal instability formation. The second group with a centromeric breakpoint of the recipient chromosome is defined by mutation and/or loss of TP53. We, therefore, assume that both critically short telomeres as well as pathogenic variants of TP53 influence jumping translocation formation.

Characterization of an acquired jumping translocation involving 3q13.31-qter in a patient with de novo acute monocytic leukemia

We studied an adult with de novo acute monocytic leukemia and a dismal outcome where her leukemic cells harbored an acquired rare jumping translocation (JT). We used oligo-based array CGH (oaCGH) analysis, fluorescence in situ hybridization (FISH), and 24-color karyotyping to enhance the characterization of the JT. G-banding detected a JT involving the 3q13.3-qter chromosomal segment and the recipient chromosomal regions 17p, 8q, and 15q. Each clone with JT was associated with trisomy 8. oaCGH analysis revealed an additional submicroscopic deletion in 3q13.31 as well as small subtelomeric duplications on several chromosomes. Locus-specific FISH with BAC-based probes from the 3q13.31-q13.32 region showed great heterogeneity. Telomere FISH revealed significantly reduced telomeric content in the aberrant cells with JT compared with cytogenetically normal cells at diagnosis and in normal cells at complete remission. A literature search revealed two previous de novo AML-M5 cases of JT involving the 3q13.3-qter chromosomal segment and concomitant trisomy 8. In addition, a case with an unbalanced der(Y)t(Y;3)(q12;q13.31) and additional trisomy 8 was previously reported in a patient with de novo AML-M5. All of these cases had a dismal outcome. In the present case, and in the der(Y)t(Y;3) case, a concurrent submicroscopic deletion at 3q13.31 was observed affecting the TUSC7 gene. Duplication of 3q13.31-qter might be a non-random chromosomal abnormality with concomitant submicroscopic deletion at 3q13.31 occurring in rare cases of acute monocytic leukemia, being associated with adverse prognosis. The impact of shortened telomeres in forming the JT is reviewed.

Jumping translocations in myelodysplastic syndromes

Jumping translocations (JT) have been identified in numerous malignancies, including leukemia, but infrequently in patients with myelodysplastic syndromes (MDS). The responsible genetic region has been mapped to the JTB gene at 1q21, but breakpoints involving other chromosomal loci, such as 3q and 11q, have been described as well. We have characterized the pathological and mutational landscape, and the clinical course of 6 new MDS patients with jumping mutations using chromosome genomic array testing (CGAT) and target gene panel next generation sequencing. In addition, we have performed a literature review for other MDS cases with JTs as defined by ISCN 2013. Results support the concept that MDS in patients with jumping translocations has a poor prognosis with a high risk of progression to leukemia, and suggest that these patients warrant aggressive therapy, including HCT, early in the disease course.

Jumping translocation in a case of de novo infant acute myeloid leukemia

An infant presented with fever and purulent discharge from the left ear, proptosis of the right eye, and hepatosplenomegaly. She was diagnosed with acute monoblastic leukemia on morphological and flowcytometric analysis of the bone marrow. Karyotyping showed a jumping translocation (JT) involving the long arm of chromosome 1 as the sole cytogenetic abnormality in 29 metaphases. The patient died within 2 months of diagnosis. The presence of JT in a de novo infant AML as a sole cytogenetic abnormality indicates its possible role in leukemogenesis unlike previous reports that have implicated its role in tumor progression only.

Delta-lactoferrin, an intracellular lactoferrin isoform that acts as a transcription factor1This article is part of a Special Issue entitled Lactoferrin and has undergone the Journal's usual peer review process

Delta-lactoferrin (ΔLf) is a transcription factor of which the expression is downregulated in cancer. It is a healthy tissue marker and a high expression level of its transcripts was correlated with a good prognosis in breast cancer. ΔLf results from alternative promoter usage of the hLf gene leading to the production of 2 isoforms with alternative N-termini: lactoferrin, which is secreted, and ΔLf, its nucleocytoplasmic counterpart. ΔLf possesses antiproliferative properties and induces cell cycle arrest. It is an efficient transcription factor interacting in vivo via a ΔLf response element found in the Skp1, Bax, DcpS, and SelH promoters. Since ΔLf possesses different target genes, modifications in its activity or concentration may have crucial effects on cell homeostasis. Posttranslational modifications modulate ΔLf transcription factor activity. Our earlier investigations showed that O-GlcNAcylation negatively regulates ΔLf transcriptional activity, whilst inhibiting its ubiquitination and increasing its half-life. On the other hand, phosphorylation potentiates ΔLf transcriptional activity. Recently, we showed that ΔLf is also modified by SUMOylation. Therefore, cooperation and (or) competition among SUMOylation, ubiquitination, phosphorylation, and O-GlcNAcylation may contribute to the establishment of a fine regulation of ΔLf transcriptional activity depending on the type of target gene and cellular homeostasis.