Identification of a YAC spanning the translocation breakpoint t(8;22) associated with acute monocytic leukemia

Sea-Blue Histiocytosis of Bone Marrow in a Patient with t(8;22) Acute Myeloid Leukemia

An 80-year-old Japanese male was treated with chemotherapy consisting of cyclophosphamide, doxorubicin, vincristine, and prednisolone, for non-Hodgkin lymphoma. Nine months after the chemotherapy, he was diagnosed with acute myeloid leukemia (AML) (M4) with translocation 8p11 and 22q13. The patient bone marrow indicated a remarkable degree of sea-blue histiocytosis. His disease was aggressive, and he died of the disease. Sea-blue histiocytes are macrophages harboring blue vacuoles and granular deposition, which results from the phagocytosis of dead cells and the subsequent deposition of phospholipids. AML with the t(8; 22) (p11; q13) translocation is a rare subtype of AML, which is a rare translocation with a prevalence of less than 1.0% among all AML cases. The oncogenesis of t(8; 22) (p11; q13) is caused by the fusion protein monocytic leukemia zinc finger protein (MOZ) and transcription factor p300. MOZ can be fused to various translocation targets including CBT, TIF2, and p300, corresponding to t(8; 16), inv(8), and t(8; 22), respectively. This subgroup of AML reveals the hallmarks of the disease, including monocytic arrest and erythro/hemophagocytosis by blasts. A substantial proportion of the AML M4/M5 subtype harboring MOZ as an aberrant fusion gene represents erythrophagocytosis. Although rare, t(8; 22) is very specific to the AML M4/M5 subtype and seems to represent sea-blue histiocytosis as one of the characteristic features of monocytic AML with macrophage activation. Thus, sea-blue histiocytes are considered to be one of hallmarks in monocytic AML with MOZ translocation.

Acute myeloid leukaemia with 8p11 (MYST3) rearrangement: an integrated cytologic, cytogenetic and molecular study by the groupe francophone de cytogénétique hématologique

Thirty cases of acute myeloid leukaemia (AML) with MYST histone acetyltransferase 3 (MYST3) rearrangement were collected in a retrospective study from 14 centres in France and Belgium. The mean age at diagnosis was 59.4 years and 67% of the patients were females. Most cases (77%) were secondary to solid cancer (57%), haematological malignancy (35%) or both (8%), and appeared 25 months after the primary disease. Clinically, cutaneous localization and disseminated intravascular coagulation were present in 30 and 40% of the cases, respectively. AMLs were myelomonocytic (7%) or monocytic (93%), with erythrophagocytosis (75%) and cytoplasmic vacuoles (75%). Immunophenotype showed no particularity compared with monocytic leukaemia without MYST3 abnormality. Twenty-eight cases carried t(8;16)(p11;p13) with MYST3-CREBBP fusion, one case carried a variant t(8;22)(p11;q13) and one case carried a t(8;19)(p11;q13). Type I (MYST3 exon 16-CREBBP exon 3) was the most frequent MYST3-CREBBP fusion transcript (65%). MYST3 rearrangement was associated with a poor prognosis, as 50% of patients deceased during the first 10 months. All those particular clinical, cytologic, cytogenetic, molecular and prognostic characteristics of AML with MYST3 rearrangement may have allowed an individualization into the World Health Organization classification.

Absence of p300 gene promoter methylation in acute leukemia

p300 is a widely expressed transcriptional coactivator, and is involved in DNA repair, cell growth, differentiation, and apoptosis. Recent data suggest that it may function as a tumor suppressor. We investigated the frequency of aberrant methylation of p300 promoter in seven leukemic cell lines, as well as in the diagnostic samples of 46 patients with acute myelocytic leukemia (11 with M1, 22 with M2, 3 with M4, and 1 with M5), 24 patients with acute promyelocytic leukemia, and 22 patients with acute lymphoblastic leukemia (3 with T-cell, 1 with pre-B, 2 with Burkitt, 2 with early B-precursors, and 14 with common). None of the cell lines and patient samples showed p300 gene methylation. Therefore, hypermethylation of p300 is not an important mechanism in leukemogenesis.

Fusion of MOZ and p300 histone acetyltransferases in acute monocytic leukemia with a t(8;22)(p11;q13) chromosome translocation

Histone acetyltransferase p300 functions as a transcriptional co-activator which interacts with a number of transcription factors. Monocytic leukemia zinc finger protein (MOZ) has histone acetyltransferase activity. We report the fusion of the MOZ gene to the p300 gene in acute myeloid leukemia with translocation t(8;22)(p11;q13). FISH and Southern blot analyses showed the rearrangement of the MOZ and p300 genes. We determined the genomic structure of the p300 and the MOZ genes and the breakpoints of the translocation. Analysis of fusion transcripts indicated that the zinc finger and acetyltransferase domains of MOZ are fused to a largely intact p300. These results suggest that MOZ-p300, which has two acetyltransferase domains, could be involved in leukemogenesis through aberrant regulation of histone acetylation.

MOZ is fused to p300 in an acute monocytic leukemia with t(8;22)

We report on the fusion of the monocytic leukemia zinc finger protein (MOZ) gene to the adenoviral E1A-associated protein p300 (p300) gene in acute monocytic leukemia M5 associated with a t(8;22)(p11;q13) translocation. We studied two patients with double-color fluorescence in situ hybridization (FISH) using the yeast artificial chromosome 176C9 and the bacterial artificial chromosome clone H59D10 specific to the MOZ and p300 genes, respectively. Both probes were split in the patients' chromosome metaphase cells, and the two derivative chromosomes were each labeled with both probes. We showed by Southern blot the rearrangement of the MOZ gene, and cloned the fusion transcripts in one patient carrying the t(8;22) by reverse transcription-polymerase chain reaction using MOZ- and p300-specific primers. Both fusion transcripts were expressed. This result defines a novel reciprocal translocation involving two acetyltransferases, MOZ and p300, resulting in an abnormal transcriptional co-activator that could play a critical role in leukemogenesis.

The cloning, mapping and expression of a novel gene, BRL, related to the AF10 leukaemia gene

The MLL gene is reciprocally translocated with one of a number of different partner genes in a proportion of human acute leukaemias. The precise mechanism of oncogenic transformation is unclear since most of the partner genes encode unrelated proteins. However, two partner genes, AF10 and AF17 are related through the presence of a cysteine rich region and a leucine zipper. The identification of other proteins with these structures will aid our understanding of their role in normal and leukaemic cells. We report the cloning of a novel human gene (BRL) which encodes a protein containing a cysteine rich region related to that of AF10 and AF17 and is overall most closely related to the previously known protein BR140. BRL maps to chromosome 22q13 and shows high levels of expression in testis and several cell lines. The deduced protein sequence also contains a bromodomain, four potential LXXLL motifs and four predicted nuclear localization signals. A monoclonal antibody raised to a BRL peptide sequence confirmed its widespread expression as a 120 Kd protein and demonstrated localization to the nucleus within spermatocytes.

The t(6;8)(q27;p11) Translocation in a Stem Cell Myeloproliferative Disorder Fuses a Novel Gene, FOP, to Fibroblast Growth Factor Receptor 1

In patients with an atypical stem-cell myeloproliferative disorder with lymphoma (B or T cell), myeloid hyperplasia, and eosinophilia, the chromosome 8p11-12 region is the site of a recurrent breakpoint that can be associated with three different partners, 6q27, 9q32-34, and 13q12. Rearrangements are supposed to affect a pluripotent stem cell capable of myeloid and lymphoid differentiation and to involve the same 8p11-12 gene. The t(8;13) translocation has recently been shown to result in a fusion between the FGFR1 gene that encodes a tyrosine kinase receptor for fibroblast growth factors and a novel gene, FIM (also called RAMP or ZNF198), belonging to a novel family of zinc finger genes. In the present study, we have cloned the t(6;8)(q27;p11) translocation in two patients and found a fusion between FGFR1 and a novel gene, FOP(FGFR1Oncogene Partner), located on chromosome band 6q27. This gene is alternatively spliced and ubiquitously expressed. It encodes a protein containing two regions of putative leucine-rich repeats putatively folding in -helices and separated by a hydrophobic spacer. The two reciprocal fusion transcripts were evidenced by reverse transcription-polymerase chain reaction in the tumoral cells of the patients. The predicted chimeric FOP-FGFR1 protein contains the FOP N-terminus leucine-rich region fused to the catalytic domain of FGFR1. It may promote hematopoietic stem cell proliferation and leukemogenesis through a constitutive phosphorylation and activation of the downstream pathway of FGFR1.

The t(6;8)(q27;p11) Translocation in a Stem Cell Myeloproliferative Disorder Fuses a Novel Gene, FOP, to Fibroblast Growth Factor Receptor 1

In patients with an atypical stem-cell myeloproliferative disorder with lymphoma (B or T cell), myeloid hyperplasia, and eosinophilia, the chromosome 8p11-12 region is the site of a recurrent breakpoint that can be associated with three different partners, 6q27, 9q32-34, and 13q12. Rearrangements are supposed to affect a pluripotent stem cell capable of myeloid and lymphoid differentiation and to involve the same 8p11-12 gene. The t(8;13) translocation has recently been shown to result in a fusion between the FGFR1 gene that encodes a tyrosine kinase receptor for fibroblast growth factors and a novel gene, FIM (also called RAMP or ZNF198), belonging to a novel family of zinc finger genes. In the present study, we have cloned the t(6;8)(q27;p11) translocation in two patients and found a fusion between FGFR1 and a novel gene, FOP(FGFR1Oncogene Partner), located on chromosome band 6q27. This gene is alternatively spliced and ubiquitously expressed. It encodes a protein containing two regions of putative leucine-rich repeats putatively folding in -helices and separated by a hydrophobic spacer. The two reciprocal fusion transcripts were evidenced by reverse transcription-polymerase chain reaction in the tumoral cells of the patients. The predicted chimeric FOP-FGFR1 protein contains the FOP N-terminus leucine-rich region fused to the catalytic domain of FGFR1. It may promote hematopoietic stem cell proliferation and leukemogenesis through a constitutive phosphorylation and activation of the downstream pathway of FGFR1.

Histogenetic relations between giant cell fibroblastoma and dermatofibrosarcoma protuberans. CD34 staining showing the spectrum and a simulator

The authors describe three lesions that provide further evidence for a close, possibly histogenetic relation between giant cell fibroblastoma and dermatofibrosarcoma protuberans. The first case involves a dermatofibrosarcoma protuberans that contained a single giant cell fibroblastoma-like focus of multi-nucleate giant cells. A second tumor, a giant cell fibroblastoma, recurred 6 years later as a dermatofibrosarcoma protuberans. In the third lesion, there was a juxtaposition and co-mingling of dermatofibrosarcoma protuberans and giant cell fibroblastoma within the same primary lesion. In all cases, both the giant cell fibroblastoma areas and dermatofibrosarcoma protuberans areas stained positively with CD34. A fourth case, a dermatofibrosarcoma protuberans infiltrated skeletal muscle, creating giant cell fibroblastoma-like giant cell mimics--a result of skeletal muscle degeneration or atrophy with nuclear conglomeration. The latter giant cells failed to express CD34 but did show immunoreactivity with desmin. These findings support the concept that giant cell fibroblastoma and dermatofibrosarcoma protuberans probably represent a histologic spectrum of a single CD34 positive (perhaps, dermal dendrocytic) neoplasm, a conclusion supported by a recently cloned t(7;22) breakpoint demonstrated in both neoplasms.

Chromosome region 8p11-p21: refined mapping and molecular alterations in breast cancer

Several genes, most of them unknown, of the short arm of chromosome 8 are involved in malignant diseases. Numerous studies have implicated a portion of the 8p11-p21 region as the location of one or more tumor suppressor genes involved in a variety of human cancers, including breast cancer. We and others have reported linkage analyses suggesting the presence of a putative breast cancer susceptibility gene. Furthermore, several oncogenes of the 8p11-p12 region are involved in reciprocal translocations in myeloproliferative and myelodysplastic disorders and in amplification in breast cancer. To facilitate the analysis of the 8p11-p21 region and the cloning of candidate oncogenes and tumor suppressor genes, a high-resolution physical and transcriptional map was established with 39 yeast artificial chromosomes and 94 markers, including so-called sequence-tagged sites and expressed sequence-tagged sites derived from either known genes or expressed sequence tags corresponding to unidentified transcripts. In addition, four novel transcripts were identified and localized precisely within the map. This transcription map provides a detailed description of gene order for the 8p11-p21 region and will be helpful in the identification of candidate genes for diseases. From this basis, we refined the mapping of two types of molecular alterations that occur at 8p11-p21 in sporadic breast cancers, i.e., amplification and deletion.

Fibroblast growth factor receptor 1 is fused to FIM in stem-cell myeloproliferative disorder with t(8;13)

Chromosome 8p11-12 is the site of a recurrent breakpoint in a myeloproliferative disorder that involves lymphoid (T- or B-cell), myeloid hyperplasia and eosinophilia, and evolves toward acute leukemia. This multilineage involvement suggests the malignant transformation of a primitive hematopoietic stem cell. In this disorder, the 8p11-12 region is associated with three different partners 6q27, 9q33, and 13q12. We describe here the molecular characterization of the t(8;13) translocation that involves the FGFR1 gene from 8p12, encoding a tyrosine kinase receptor for members of the fibroblast growth factor family, and a gene from 13q12, tentatively named FIM (Fused In Myeloproliferative disorders). FIM is related to DXS6673E, a candidate gene for X-linked mental retardation in Xq13.1; this defines a gene family involved in different human pathologies. The two reciprocal fusion transcripts, FIM/FGFR1 and FGFR1/FIM are expressed in the malignant cells. The FIM/FGFR1 fusion protein contains the FIM putative zinc finger motifs and the catalytic domain of FGFR1. We show that it has a constitutive tyrosine kinase activity.

Characterization of the breakpoints in a t(8;13)(p11;q12) translocation from a patient with myeloproliferative disease using fluorescence in situ hybridization

We used fluorescence in situ hybridization to characterize the molecular position of the breakpoints in a t(8;13)(p11;q12) reciprocal translocation from a patient with an atypical myeloproliferative disorder. This structural chromosome abnormality is characteristic of this specific disease and occurs often as the only chromosome abnormality in the malignant cells. Yeast artificial chromosome (YAC) analysis has demonstrated that the 8p11 breakpoint lies within a region defined by YAC 959A4 and that the 13q12 breakpoint is spanned by YAC 769F9. Identifying the position of the breakpoints in this rearrangement provides the means to search for candidate genes rearranged by this highly specific structural chromosome abnormality.

Abnormalities of Chromosome Band 8p11 in Leukemia: Two Clinical Syndromes Can Be Distinguished on the Basis of MOZ Involvement

Two distinct leukemia syndromes are associated with abnormalities of chromosome band 8p11. First, a myeloproliferative disorder with features characteristic of both chronic myeloid leukemia and non-Hodgkin's lymphoma and second, an acute myeloid leukemia (AML) with French-American-British (FAB) M4/5 morphology and prominent erythrophagocytosis. The two syndromes are exemplified by a t(8; 13)(p11; q12) and a t(8; 16)(p11; p13), respectively, but cytogenetic variants of both have been described. Recently, the t(8; 16) has been cloned and shown to fuse the MOZ gene at 8p11 to the CBP gene at 16p13. We have used fluorescence in situ hybridization (FISH), Southern blotting, and reverse transcriptase-polymerase chain reaction (RT-PCR) to refine the 8p11 breakpoint in three cases with t(8; 13)(p11; q12) and in a single case of AML-M5 with a clinical picture apparently identical to that found in patients with a t(8; 16), but characterized by an inv(8)(p11q13). FISH analysis was performed with several 8p11 CEPH yeast artificial chromosome (YAC) clones. YAC 782H11 was centromeric to the one case with t(8; 13) tested, but was telomeric to the inv(8). YAC 847B12 was telomeric to both the t(8; 13) and the inv(8), whereas YAC 829D12 was centromeric to the t(8; 13), but split by the inv(8). Southern blotting and PCR of YAC 829D12 showed that it contained the MOZ gene. A 900-bp MOZ fragment encompassing the published t(8; 16) breakpoint was amplified by PCR from normal peripheral blood leukocyte cDNA and used to probe Southern blots of patient DNA. A rearrangement was detected in the case with inv(8), but not in any of the three cases with t(8; 13). Southern blotting with a CBP probe and RT-PCR with MOZ and CBP primers suggested that the inv(8) does not result in a cryptic MOZ-CBP fusion. It is likely, therefore, that MOZ is fused to a novel gene at 8q13 in this case. We conclude that the t(8; 13) breakpoint is flanked by YACs 782H11 and 847B12 and is at least 1 Mb telomeric to MOZ. MOZ is involved, however, in a new variant of the t(8; 16).

Molecular Characterization of the t(8; 13)(p11;q12) Translocation Associated With an Atypical Myeloproliferative Disorder: Evidence for Three Discrete Loci Involved in Myeloid Leukemias on 8p11

A reciprocal chromosome translocation between 13q12 and 8p11 is the consistent cytogenetic abnormality seen in a nonspecific myeloproliferative disorder that is associated with T-cell leukemia/lymphoma and peripheral blood eosinophilia. Detailed molecular analyses of the translocation breakpoints associated with this rearrangement have not been reported to date. We have now generated somatic cell hybrids from a newly described patient with this specific structural rearrangement and analyzed the breakpoints on the derivative chromosomes. We have shown that the breakpoint on chromosome 13 lies within a 300- to 500-kb region defined by the KIAA177 gene and D13S1123 marker. In addition, we have identified a 1.2-Mb YAC, 959A4, that crosses the translocation breakpoint on the short arm of chromosome 8 in this patient. The location of this breakpoint in 8p11 is distinct from the t(8; 16) and t(8; 22) translocations associated with M4/M5 myeloid leukemias, and suggests that three distinct loci located within 8p11 are involved in the pathogenesis of myeloid neoplasias.

Construction of a 1.2-Mb contig surrounding, and molecular analysis of, the human CREB-binding protein (CBP/CREBBP) gene on chromosome 16p13.3

In the interest of cloning and analyzing the genes responsible for two very different diseases, the Rubinstein-Taybi syndrome (RTS) and acute myeloid leukemia (AML) associated with the somatic translocation t(8;16)(p11;p13.3), we constructed a high-resolution restriction map of contiguous cosmids (contig) covering 1.2 Mb of chromosome 16p13.3. By fluorescence in situ hybridization and Southern blot analysis, we assigned all tested RTS and t(8;16) translocation breakpoints to a 100-kb region. We have previously reported exact physical locations of these 16p breakpoints, which all disrupt one gene we mapped to this interval: the CREB-binding protein (CBP or CREBBP) gene. Intriguingly, mutations in the CBP gene are responsible for RTS as well as the t(8;16)-associated AML. CBP functions as an integrator in the assembly of various multiprotein regulatory complexes and is thus necessary for transcription in a broad range of transduction pathways. We report here the cloning, physical mapping, characterization, and full cDNA nucleotide sequence of the human CBP gene.

Deregulation of the platelet-derived growth factor B-chain gene via fusion with collagen gene COL1A1 in dermatofibrosarcoma protuberans and giant-cell fibroblastoma

Dermatofibrosarcoma protuberans (DP), an infiltrative skin tumour of intermediate malignancy, presents specific features such as reciprocal translocations t(17;22)(q22;q13) and supernumerary ring chromosomes derived from the t(17;22). In this report, the breakpoints from translocations and rings in DP and its juvenile form, giant cell fibroblastoma (GCF), were characterised on the genomic and RNA level. These rearrangements fuse the platelet-derived growth factor B-chain (PDGFB, c-sis proto-oncogene) and the collagen type I alpha 1 (COL1A1) genes. PDGFB has transforming activity and is a potent mitogen for a number of cell types, but its role in oncogenic processes is not fully understood. COL1A1 is a major constituent of the connective tissue matrix. Neither PDGFB nor COL1A1 have so far been implicated in any tumour translocations. These gene fusions delete exon 1 of PDGFB, and release this growth factor from its normal regulation.