Inv(11)(p15q22)/NUP98-DDX10 fusion and isoforms in a new case of de novo acute myeloid leukemia

We set up a diagnostic double-color double-fusion fluorescence in situ hybridization (DCDF-FISH) assay to investigate a case of a de novo acute myeloid leukemia (AML)-M4 bearing an inv(11)(p15q22). DCDF-FISH detected the NUP98-DDX10 rearrangement as two fusion signals, at the short and the long arms of the inv(11). Reverse transcription-polymerase chain reaction (RT-PCR) and cloning experiments confirmed the NUP98-DDX10 fusion and identified two splicing fusion isoforms: the known "type II fusion," originating from the fusion of NUP98 exon 14 to DDX10 exon 7 and a new in-frame fusion transcript between NUP98 exon 15 and DDX10 exon 7, which we termed "type III fusion."

Rare t(1;11)(q23;p15) in therapy-related myelodysplastic syndrome evolving into acute myelomonocytic leukemia: a case report and review of the literature

Balanced chromosome rearrangements are the hallmark of therapy-related leukemia that develops in patients treated with topoisomerase II inhibitors. Many of these rearrangements involve recurrent chromosomal sites and associated genes (11q23/MLL, 21q22.3/AML1, and 11p15/NUP98), which can interact with a variety of partner genes. One such rearrangement is the rare t(1;11)(q23;p15), which involves juxtaposition of the homeobox gene PMX1 (PRRX1) and NUP98. We report on an additional patient with t(1;11) who presented with myelodysplastic syndrome (MDS) subsequent to treatment for a pleomorphic liposarcoma. With time, the patient's disorder progressed to acute myelomonocytic leukemia with cytogenetic evidence of clonal evolution. To our knowledge, this is the first report of a patient presenting with a myelodysplastic syndrome with isolated t(1;11) (q23;p15), which evolved into therapy-related acute myeloid leukemia (t-AML). This patient is the third reported with this cytogenetic rearrangement and t-AML, and is compared with the other two reports of t(1;11)(q23;p15).

Topoisomerase II and the etiology of chromosomal translocations

Acute leukemias with balanced chromosomal translocations, protean morphologic and immunophenotypic presentations but generally shorter latency and absence of myelodysplasia are recognized as a complication of anti-cancer drugs that behave as topoisomerase II poisons. Translocations affecting the breakpoint cluster region of the MLL gene at chromosome band 11q23 are the most common molecular genetic aberrations in leukemias associated with the topoisomerase II poisons. These agents perturb the cleavage-religation equilibrium of topoisomerase II and increase cleavage complexes. One model suggests that this damages the DNA directly and leads to chromosomal breakage, which may result in untoward DNA recombination in the form of translocations. This review will summarize the evidence for topoisomerase II involvement in the genesis of translocations and extension of the model to acute leukemia in infants characterized by similar MLL translocations.

Rare recurring balanced chromosome abnormalities in therapy-related myelodysplastic syndromes and acute leukemia: report from an international workshop

Seventy-seven patients were identified with Rare recurring (excluding 11q23, 21q22, inv(16), and t(15;17)) chromosome abnormalities among 511 patients with treatment-related myelodysplastic syndromes and acute leukemia accepted from centers in the United States, Europe, and Japan. The abnormality subsets included 3q21q26 (17 patients), 11p15 (17 patients), t(9;22)(q34;q11) (10 patients), 12p13 (9 patients), t(8;16)(p11;p13) (9 patients), and an "other" subset, which included t(6;9)(p23;q34) (3 patients), t(10;11)(p13;q13 approximately q21) (3 patients), t(1;17)(p36;q21) (2 patients), t(8;14)(q24;q32) (2 patients), t(11;19)(q13;q13) (2 patients), t(1;3)(p36;q21) (2 patients), and t(3;5)(q21;q31) (1 patient). Increased karyotypic complexity with additional balanced and unbalanced rearrangements was observed in 70% of cases. Among 54 cases with secondary abnormalities, chromosome 5 and/or 7 abnormalities were observed in 59%. The most frequent primary diseases were breast cancer (24 cases), Hodgkin disease (14 cases), non-Hodgkin lymphoma (10 cases), and de novo ALL (5 cases). Thirty-seven patients received alkylating agents plus topoisomerase II inhibitors with or without radiation therapy. The presenting diagnosis was t-AML in 47 cases, t-MDS in 23 cases (10 progressed to t-AML), and t-ALL in seven cases, five of whom had a t(9;22). The median latency time from initiation of original therapy to therapy-related disease diagnosis was quite long (69 months), and the overall median survival from the date of therapy-related disease diagnosis was very short (7 months). The 1-year survival rate was 34 +/- 7%, with no significant differences among subsets. Comparison with previously reported cases showed increased karyotypic complexity and adult presentation of pediatric-associated chromosome abnormalities.

Involvement of the NUP98 gene in a chromosomal translocation t(11;20)(p15;q11.2) in a patient with acute monocytic leukemia (FAB-M5b)

We report here a case of acute monocytic leukemia (M5b subtype according to the French-American-British [FAB] classification) with chromosomal translocation t(11;20)(p15;q11.2). Fluorescence in situ hybridization analysis with a probe for the NUP98 gene, which is located at chromosome band 11p15, showed that the probe hybridized to both derivative chromosomes 11 and 20 as well as to the remaining normal chromosome 11, indicating that the NUP98 gene was split and involved in this translocation. This is the first report of t(11;20)(p15;q11.2) involving the NUP98 gene in overt leukemia.

Leukemias related to treatment with DNA topoisomerase II inhibitors

The epipodophyllotoxins etoposide and teniposide and other DNA topoisomerase II inhibitors including anthracyclines and dactinomycin are highly efficacious anticancer drugs. All are associated with a distinct form of leukemia characterized by chromosomal translocations as a treatment complication. Most of the translocations disrupt a breakpoint cluster region (bcr) of the MLL gene at chromosome band 11q23. Other characteristic translocations also may occur. The normal function of the nuclear enzyme DNA topoisomerase II is to catalyze changes in DNA topology between relaxed and supercoiled states by transiently cleaving and re-ligating both strands of the double helix. Anticancer drugs that are DNA topoisomerase II inhibitors are cytotoxic because they form complexes with DNA and DNA topoisomerase II. The complexes decrease the re-ligation rate, disrupt the cleavage-re-ligation equilibrium, and have a net effect of increasing cleavage. The increased cleavage damages the DNA and leads to chromosomal breakage. Cells with irreparable DNA damage die by apoptosis. The association of DNA topoisomerase II inhibitors with leukemia suggests that the drug-induced, DNA topoisomerase II-mediated chromosomal breakage may be relevant to translocations in addition to this anti-neoplastic, cytotoxic action. Epidemiological studies, genomic translocation breakpoint cloning and in vitro DNA topoisomerase II cleavage assays together lead to a model for treatment-related leukemia in which DNA topoisomerase II causes chromosomal breakage and translocations form when the breakage is repaired.

Role for CCG-trinucleotide repeats in the pathogenesis of chronic lymphocytic leukemia

Chromosome 11q deletions are frequently observed in chronic lymphocytic leukemia (CLL) in association with progressive disease and a poor prognosis. A minimal region of deletion has been assigned to 11q22-q23. Trinucleotide repeats have been associated with anticipation in disease, and evidence of anticipation has been observed in various malignancies including CLL. Loss of heterozygosity at 11q22-23 is common in a wide range of cancers, suggesting this is an unstable area prone to chromosome breakage. The location of 8 CCG-trinucleotide repeats on 11q was determined by Southern blot analysis of a 40-Mb YAC and PAC contig spanning 11q22-qter. Deletion breakpoints in CLL are found to co-localize at specific sites on 11q where CCG repeats are located. In addition, a CCG repeat has been identified within the minimal region of deletion. Specific alleles of this repeat are associated with worse prognosis. Folate-sensitive fragile sites are regions of late replication and are characterized by CCG repeats. The mechanism for chromosome deletion at 11q could be explained by a delay in replication. Described here is an association between CCG repeats and chromosome loss suggesting that in vivo "fragile sites" exist on 11q and that the instability of CCG repeats may play an important role in the pathogenesis of CLL.

Generation of the NUP98-HOXD13 fusion transcript by a rare translocation, t(2;11)(q31;p15), in a case of infant leukaemia

We report a case of de novo acute myelomonocytic leukaemia with the t(2;11)(q31;p15) translocation in a Japanese female infant. The NUP98-HOXD13 fusion transcript generated by the translocation was detected in the patient's bone marrow cells by reverse transcription-polymerase chain reaction (RT-PCR). Additionally, ectopic expression of the normal allele of the HOXD13 gene was observed in this patient, suggesting that it might be associated with leukaemogenic development. This case is the third report of t(2;11) leukaemia with NUP98-HOXD13 and the first report showing that NUP98 rearrangements are associated with infant leukaemia, as well as therapy-related acute myelogenous leukaemia or myelodysplastic syndrome.

The t(11;20)(p15;q11) Chromosomal Translocation Associated With Therapy-Related Myelodysplastic Syndrome Results in anNUP98-TOP1 Fusion

The NUP98 gene is involved in 3 distinct chromosomal rearrangements, t(7;11)(p15;p15), t(2;11)(q31;p15), and inv(11)(p15q22); all of these NUP98 rearrangements have been identified in the malignant cells of patients with therapy-related acute myelogenous leukemia or myelodysplastic syndrome (t-AML/MDS). Here we report the cloning and characterization of a t(11;20)(p15;q11) translocation from patients with t-MDS. The breakpoint on chromosome 11p15 targets the NUP98 gene and results in the separation of the N-terminal FXFG repeats from the RNA-binding domain located in the C-terminus. The breakpoint on chromosome 20q11 occurs within the gene encoding human DNA topoisomerase I (TOP1). As a result, a chimeric mRNA encoding the NUP98 FXFG repeats fused to the body of DNA topoisomerase I is produced. These results indicate that NUP98is a recurrent target in therapy-related malignancies, and thatTOP1 is a previously unrecognized target for chromosomal translocations.

The t(11;20)(p15;q11) Chromosomal Translocation Associated With Therapy-Related Myelodysplastic Syndrome Results in anNUP98-TOP1 Fusion

The NUP98 gene is involved in 3 distinct chromosomal rearrangements, t(7;11)(p15;p15), t(2;11)(q31;p15), and inv(11)(p15q22); all of these NUP98 rearrangements have been identified in the malignant cells of patients with therapy-related acute myelogenous leukemia or myelodysplastic syndrome (t-AML/MDS). Here we report the cloning and characterization of a t(11;20)(p15;q11) translocation from patients with t-MDS. The breakpoint on chromosome 11p15 targets the NUP98 gene and results in the separation of the N-terminal FXFG repeats from the RNA-binding domain located in the C-terminus. The breakpoint on chromosome 20q11 occurs within the gene encoding human DNA topoisomerase I (TOP1). As a result, a chimeric mRNA encoding the NUP98 FXFG repeats fused to the body of DNA topoisomerase I is produced. These results indicate that NUP98is a recurrent target in therapy-related malignancies, and thatTOP1 is a previously unrecognized target for chromosomal translocations.

Constitutional balanced pericentric inversions of chromosomes X, 2, and 5 in myeloid malignancies

We report four cases of unrelated adult males carrying constitutive balanced pericentric inversions of chromosome X (one case), chromosome 2 (one case), and chromosome 5 (two cases) and presenting with myeloid malignancies. We discuss the potential contribution of these abnormalities to a background of susceptibility to hematologic malignancies.