Interleukin 4 induces apoptosis of acute myeloid leukemia cells in a Stat6-dependent manner

Cytokines provide signals that regulate immature normal and acute myeloid leukemia (AML) cells in the bone marrow microenvironment. We here identify interleukin 4 (IL4) as a selective inhibitor of AML cell growth and survival in a cytokine screen using fluorescently labeled AML cells. RNA-sequencing of the AML cells revealed an IL4-induced upregulation of Stat6 target genes and enrichment of apoptosis-related gene expression signatures. Consistent with these findings, we found that IL4 stimulation of AML cells induced Stat6 phosphorylation and that disruption of Stat6 using CRISPR/Cas9-genetic engineering rendered cells partially resistant to IL4-induced apoptosis. To evaluate whether IL4 inhibits AML cells in vivo, we expressed IL4 ectopically in AML cells transplanted into mice and also injected IL4 into leukemic mice; both strategies resulted in the suppression of the leukemia cell burden and increased survival. Notably, IL4 exposure caused reduced growth and survival of primary AML CD34⁺CD38^- patient cells from several genetic subtypes of AML, whereas normal stem and progenitor cells were less affected. The IL4-induced apoptosis of AML cells was linked to Caspase-3 activation. Our results demonstrate that IL4 selectively induces apoptosis of AML cells in a Stat6-dependent manner-findings that may translate into new therapeutic opportunities in AML.

SOCS2 is dispensable for BCR/ABL1-induced chronic myeloid leukemia-like disease and for normal hematopoietic stem cell function

Suppressor of cytokine signaling 2 (SOCS2) is known as a feedback inhibitor of cytokine signaling and is highly expressed in primary bone marrow (BM) cells from patients with chronic myeloid leukemia (CML). However, it has not been established whether SOCS2 is involved in CML, caused by the BCR/ABL1 fusion gene, or important for normal hematopoietic stem cell (HSC) function. In this study, we demonstrate that although Socs2 was found to be preferentially expressed in long-term HSCs, Socs2-deficient HSCs were indistinguishable from wild-type HSCs when challenged in competitive BM transplantation experiments. Furthermore, by using a retroviral BCR/ABL1-induced mouse model of CML, we demonstrate that SOCS2 is dispensable for the induction and propagation of the disease, suggesting that the SOCS2-mediated feedback regulation of the JAK/STAT pathway is deficient in BCR/ABL1-induced CML.

Whole-exome sequencing of pediatric acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL), the most common malignant disorder in childhood, is typically associated with numerical chromosomal aberrations, fusion genes or small focal deletions, thought to represent important pathogenetic events in the development of the leukemia. Mutations, such as single nucleotide changes, have also been reported in childhood ALL, but these have only been studied by sequencing a small number of candidate genes. Herein, we report the first unbiased sequencing of the whole exome of two cases of pediatric ALL carrying the ETV6/RUNX1 (TEL/AML1) fusion gene (the most common genetic subtype) and corresponding normal samples. A total of 14 somatic mutations were identified, including four and seven protein-altering nucleotide substitutions in each ALL. Twelve mutations (86%) occurred in genes previously described to be mutated in other types of cancer, but none was found to be recurrent in an extended series of 29 ETV6/RUNX1-positive ALLs. The number of single nucleotide mutations was similar to the number of copy number alterations as detected by single nucleotide polymorphism arrays. Although the true pathogenetic significance of the mutations must await future functional evaluations, this study provides a first estimate of the mutational burden at the genetic level of t(12;21)-positive childhood ALL.

Combined high-resolution array-based comparative genomic hybridization and expression profiling of ETV6/RUNX1-positive acute lymphoblastic leukemias reveal a high incidence of cryptic Xq duplications and identify several putative target genes within the commonly gained region

Seventeen ETV6/RUNX1-positive pediatric acute lymphoblastic leukemias were investigated by high-resolution array-based comparative genomic hybridization (array CGH), gene expression profiling and fluorescence in situ hybridization. Comparing the array CGH and gene expression patterns revealed that genomic imbalances conferred a great impact on the expression of genes in the affected regions. The array CGH analyses identified a high frequency of cytogenetically cryptic genetic changes, for example, del(9p) and del(12p). Interestingly, a duplication of Xq material, varying between 30 and 60 Mb in size, was found in 6 of 11 males (55%), but not in females. Genes on Xq were found to have a high expression level in cases with dup(Xq); a similar overexpression was confirmed in t(12;21)-positive cases in an external gene expression data set. By studying the expression profile and the proposed function of genes in the minimally gained region, several candidate target genes (SPANXB, HMGB3, FAM50A, HTATSF1 and RAP2C) were identified. Among them, the testis-specific SPANXB gene was the only one showing a high and uniform overexpression, irrespective of gender and presence of Xq duplication, suggesting that this gene plays an important pathogenetic role in t(12;21)-positive leukemia.

Deregulation of the Wilms' tumour gene 1 protein (WT1) by BCR/ABL1 mediates resistance to imatinib in human leukaemia cells

The Wilms' tumour gene 1 (WT1) protein is highly expressed in most leukaemias. Co-expression of WT1 and the fusion protein AML1-ETO in mice rapidly induces acute myeloid leukaemia (AML). Mechanisms behind expression of WT1, as well as consequences thereof, are still unclear. Here, we report that the fusion protein BCR/ABL1 increases expression of WT1 mRNA and protein via the phosphatidylinositol-3 kinase (PI3K)-Akt pathway. Inhibition of BCR/ABL1 or PI3K activity strongly suppressed transcription from WT1 promoter/enhancer reporters. Forced expression of BCR/ABL1 in normal human progenitor CD34+ cells increased WT1 mRNA and protein, further supporting the notion of BCR/ABL1-driven expression of WT1 in human haematopoietic cells. Forced expression of WT1 in K562 cells provided protection against cytotoxic effects of the ABL1 tyrosine kinase inhibitor imatinib, as judged by effects on viability measured by trypan blue exclusion, metabolic activity, annexin V and DAPI (4', 6-diamidino-2-phenylindole) staining. None of the isoforms provided any detectable protection against apoptosis induced by arsenic trioxide and only very weak protection against etoposide, indicating that WT1 interferes with specific apoptotic signalling pathways. Our data demonstrate that WT1 expression is induced by oncogenic signalling from BCR/ABL1 and that WT1 contributes to resistance against apoptosis induced by imatinib.

Microarray-based classification of a consecutive series of 121 childhood acute leukemias: prediction of leukemic and genetic subtype as well as of minimal residual disease status

Gene expression analyses were performed on 121 consecutive childhood leukemias (87 B-lineage acute lymphoblastic leukemias (ALLs), 11 T-cell ALLs and 23 acute myeloid leukemias (AMLs)), investigated during an 8-year period at a single center. The supervised learning algorithm k-nearest neighbor was utilized to build gene expression predictors that could classify the ALLs/AMLs according to clinically important subtypes with high accuracy. Validation experiments in an independent data set verified the high prediction accuracies of our classifiers. B-lineage ALLs with uncharacteristic cytogenetic aberrations or with a normal karyotype displayed heterogeneous gene expression profiles, resulting in low prediction accuracies. Minimal residual disease status (MRD) in T-cell ALLs with a high (>0.1%) MRD at day 29 could be classified with 100% accuracy already at the time of diagnosis. In pediatric leukemias with uncharacteristic cytogenetic aberrations or with a normal karyotype, unsupervised analysis identified two novel subgroups: one consisting mainly of cases remaining in complete remission (CR) and one containing a few patients in CR and all but one of the patients who relapsed. This study of a consecutive series of childhood leukemias confirms and extends further previous reports demonstrating that global gene expression profiling provides a valuable tool for genetic and clinical classification of childhood leukemias.

Cytogenetic evolution patterns in CML post-SCT

The cytogenetic evolution patterns in chronic myeloid leukemia (CML) after allogeneic (allo) stem cell transplantation (SCT) are different from the ones observed in non-transplanted patients, a phenomenon suggested to be caused by the conditioning regime. We reviewed 131 CMLs displaying karyotypic evolution after SCT (122 allo, nine autologous (auto)), treated at Lund University Hospital or reported in the literature. Major route abnormalities (i.e., +8, +Ph, i(17q), +19, +21, +17 and -7) were seen in 14%, balanced aberrations in 61%, hyperdiploidy in 19%, pseudodiploidy in 79%, divergent clones in 14%, and Ph-negative clones in 21%. The breakpoints involved in secondary structural rearrangements clustered at 1q21, 1q32, 7q22, 9q34, 11q13, 11q23, 12q24, 13q14, 17q10 and 22q11. Cytogenetic abnormalities common in AML after genotoxic exposure, that is, der(1;7)(q10;p10), del(3p), -5, del(5q), -7, -17, der(17p), -18, and -21, were only rarely seen post-SCT. Comparing the cytogenetic features in relation to type of SCT revealed that balanced aberrations were significantly more common after allo than after auto SCT (64 and 22%, respectively, P=0.03). In addition, there was a trend as regards hyperdiploidy being more common after auto (P=0.07) and pseudodiploidy being more frequent after allo SCT (P=0.09). Possible reasons for these differences are discussed.

Identification of cryptic aberrations and characterization of translocation breakpoints using array CGH in high hyperdiploid childhood acute lymphoblastic leukemia

High hyperdiploidy, characterized by non-random trisomies, is the largest cytogenetic subgroup in childhood acute lymphoblastic leukemia (ALL). It is not known whether the gained chromosomes are sufficient for leukemogenesis or if additional genetic aberrations are necessary. However, the suboptimal chromosome morphology of hyperdiploid ALLs makes detection of structural abnormalities difficult if using cytogenetic techniques; alternative methods are, therefore, needed. We performed array comparative genome hybridization (CGH) analyses, with a resolution of 100 kb, of eight cases of high hyperdiploid childhood ALL to characterize structural abnormalities found with G-banding/multicolor fluorescence in situ hybridization (FISH) and to detect novel changes. The non-centromeric breakpoints of four rearrangements, including three translocations and one 1q duplication, were narrowed down to <0.2 Mb. Furthermore, four submicroscopic imbalances involving 0.6-2.7 Mb were detected, comprising two segmental duplications involving 1q22 and 12q24.31 in one case and two hemizygous deletions in 12p13.2-31 - including ETV6 - and in 13q32.3-33.1 in another case. Notably, FISH analysis of the latter revealed an associated reciprocal t(3;13)(q?;32.2-33.1). In conclusion, the array CGH analyses revealed putative leukemia-associated submicroscopic imbalances and rearrangements in 2/8 (25%) hyperdiploid ALLs. The detection and characterization of these additional genetic aberrations will most likely increase our understanding of the pathogenesis of high hyperdiploid childhood ALL.

Molecular characterization of early-stage bladder carcinomas by expression profiles, FGFR3 mutation status, and loss of 9q

We used gene expression profiling, mutation analyses of FGFR3 and TP53, and LOH analyses of chromosome 9 and the TP53 region on chromosome arm 17p, to molecularly characterize 75 Ta and T1 bladder carcinomas. We identified four major cellular processes related to cell cycle, protein synthesis, immune response, and extra cellular components that contribute to the expressional heterogeneity of early-stage urothelial cell carcinoma (UCC). Activating FGFR3 mutations were found at the highest frequency in G1 tumors (80%), and showed a strong correlation with FGFR3 expression. In contrast, G3 tumors displayed mutations in less than 10% of the cases and a low level of FGFR3 expression. Even though LOH on chromosome 9 was not associated with any specific expression pattern, our data indicate that loss of chromosome 9 is associated with tumor development rather than initiation. The combined analyses suggest the existence of two types of UCC tumors, one which is characterized by FGFR3 mutation or expression, high expression of protein synthesis genes, and low expression of cell cycle genes. Furthermore, the presented data underscore FGFR3 receptor involvement in urothelial cell transformation as the presence of FGFR3 mutations has a major impact on the global gene expression profile of bladder carcinomas.

High-resolution genome-wide array-based comparative genome hybridization reveals cryptic chromosome changes in AML and MDS cases with trisomy 8 as the sole cytogenetic aberration

Although trisomy 8 as the sole chromosome aberration is the most common numerical abnormality in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS), little is known about its pathogenetic effects. Considering that +8 is a frequent secondary change in AML/MDS, cryptic--possibly primary--genetic aberrations may occur in cases with trisomy 8 as the apparently single anomaly. However, no such hidden anomalies have been reported. We performed a high-resolution genome-wide array-based comparative genome hybridization (array CGH) analysis of 10 AML/MDS cases with isolated +8, utilizing a 32K bacterial artificial chromosome array set, providing >98% coverage of the genome with a resolution of 100 kb. Array CGH revealed intrachromosomal imbalances, not corresponding to known genomic copy number polymorphisms, in 4/10 cases, comprising nine duplications and hemizygous deletions ranging in size from 0.5 to 2.2 Mb. A 1.8 Mb deletion at 7p14.1, which had occurred prior to the +8, was identified in MDS transforming to AML. Furthermore, a deletion including ETV6 was present in one case. The remaining seven imbalances involved more than 40 genes. The present results show that cryptic genetic abnormalities are frequent in trisomy 8-positive AML/MDS cases and that +8 as the sole cytogenetic aberration is not always the primary genetic event.

Gene expression profiling of leukemic cell lines reveals conserved molecular signatures among subtypes with specific genetic aberrations

Hematologic malignancies are characterized by fusion genes of biological/clinical importance. Immortalized cell lines with such aberrations are today widely used to model different aspects of leukemogenesis. Using cDNA microarrays, we determined the gene expression profiles of 40 cell lines as well as of primary leukemias harboring 11q23/MLL rearrangements, t(1;19)[TCF3/PBX1], t(12;21)[ETV6/RUNX1], t(8;21)[RUNX1/CBFA2T1], t(8;14)[IGH@/MYC], t(8;14)[TRA@/MYC], t(9;22)[BCR/ABL1], t(10;11)[PICALM/MLLT10], t(15;17)[PML/RARA], or inv(16)[CBFB/MYH11]. Unsupervised classification revealed that hematopoietic cell lines of diverse origin, but with the same primary genetic changes, segregated together, suggesting that pathogenetically important regulatory networks remain conserved despite numerous passages. Moreover, primary leukemias cosegregated with cell lines carrying identical genetic rearrangements, further supporting that critical regulatory pathways remain intact in hematopoietic cell lines. Transcriptional signatures correlating with clinical subtypes/primary genetic changes were identified and annotated based on their biological/molecular properties and chromosomal localization. Furthermore, the expression profile of tyrosine kinase-encoding genes was investigated, identifying several differentially expressed members, segregating with primary genetic changes, which may be targeted with tyrosine kinase inhibitors. The identified conserved signatures are likely to reflect regulatory networks of importance for the transforming abilities of the primary genetic changes and offer important pathogenetic insights as well as a number of targets for future rational drug design.

Establishment and phenotypic characterization of human U937 cells with inducible P210 BCR/ABL expression reveals upregulation of CEACAM1 (CD66a)

Chronic myeloid leukemia (CML) is characterized by the expression of the P210 BCR/ABL fusion protein. The molecular mechanisms behind this oncogene-mediated hematological disease are, however, not fully understood. Here, we describe the establishment and phenotypic characterization of U937 cells in which P210 BCR/ABL can be conditionally expressed using tetracycline. The induction of BCR/ABL in the obtained clones resulted in a rapid phosphorylation of the STAT1, STAT3 and STAT5 molecules, consistent with the findings in other model systems. Phenotypic characterization of the clones revealed that BCR/ABL induces a slight decrease in the proliferation and viability, without a marked effect on cell cycle distribution, the rate of apoptosis or on cellular differentiation, as judged by several cell surface markers and capacity to reduce nitro blue tetrazolium. Interestingly, BCR/ABL was found to upregulate the expression of carcinoembryonic-related antigen (CEA)CAM1 (CD66a), which is a plasma membrane-linked glycoprotein belonging to the CEAs and involved in signal transduction and cellular adhesion. The expression of CEACAM1 was reversible upon imatinib treatment in BCR/ABL-expressing U937 cells as well as in BCR/ABL-positive K562 cells. The established cell lines may prove useful in further modeling and dissection of BCR/ABL-induced leukemogenesis.

Prognostic implications of BCL6 rearrangement in uniformly treated patients with diffuse large B-cell lymphoma--a Nordic Lymphoma Group study

The purpose of this study was to investigate the prognostic implications of BCL6 rearrangement in a uniformly treated population of patients with diffuse large B-cell lymphoma (DLBCL) and to characterise the relationship between BCL6 rearrangement and prognostic factors. A total of 269 patients with DLBCL entered a randomised trial comparing the chemotherapy regimen CHOP (cyclophosphamide, doxorubicin, vincristine, prednisone) to the MACOP-B (methotrexate, doxorubicin, cyclophosphamide, vincristine, prednisone, bleomycin) regimen. In 44 cases, frozen tissue was available for assessment of BCL6 status by Southern blot analysis. BCL6 was rearranged in six of 43 evaluable cases (14%), and was associated with elevated lactate dehydrogenase (LDH), and a higher patient age. No association between BCL6 status and expression of BCL2, Ki-67 or TP53 was found. Patients presenting with BCL6 rearrangement displayed a weak trend towards better overall and failure-free survival (67 and 67% at 5 years), compared to patients with germline BCL6 (63 and 52%), but the difference was not statistically significant. In accordance with previously published series, the presence of BCL6 rearrangement does not define a prognostically distinct subgroup of DLBCL. Assessment of BCL6 status may, however, be of clinical interest when related to other prognostic variables.

Fusion of the BCR and the fibroblast growth factor receptor-1 (FGFR1) genes as a result of t(8;22)(p11;q11) in a myeloproliferative disorder: the first fusion gene involving BCR but not ABL

Constitutive activation of tyrosine kinases as a consequence of chromosomal translocations, forming fusion genes, plays an important role in the development of hematologic malignancies, in particular, myeloproliferative syndromes (MPSs). In this respect, the t(9;22)(q34;q11) that results in the BCR/ABL fusion gene in chronic myeloid leukemia is one of the best-studied examples. The fibroblast growth factor receptor 1 (FGFR1) gene at 8p11 encodes a transmembrane receptor tyrosine kinase and is similarly activated by chromosomal translocations, in which three alternative genes-ZNF198 at 13q12, CEP110 at 9q34, and FOP at 6q27-become fused to the tyrosine kinase domain of FGFR1. These 8p11-translocations are associated with characteristic morphologic and clinical features, referred to as "8p11 MPS." In this study, we report the isolation and characterization of a novel fusion gene in a hematologic malignancy with a t(8;22)(p11;q11) and features suggestive of 8p11 MPS. We show that the breakpoints in the t(8;22) occur within introns 4 and 8 of the BCR and FGFR1 genes, respectively. On the mRNA level, the t(8;22) results in the fusion of BCR exons 1-4 in-frame with the tyrosine kinase domain of FGFR1 as well as in the expression of a reciprocal FGFR1/BCR chimeric transcript. By analogy with data obtained from previously characterized fusion genes involving FGFR1 and BCR/ABL, it is likely that the oligomerization domain contributed by BCR is critical and that its dimerizing properties lead to aberrant FGFR1 signaling and neoplastic transformation.

The incidence of trisomy 8 as a sole chromosomal aberration in myeloid malignancies varies in relation to gender, age, prior iatrogenic genotoxic exposure, and morphology

Although trisomy 8 as a sole change is one of the most common chromosomal abnormalities in myeloid malignancies, it is largely unknown if the incidence of this aberration is influenced by other factors of clinical importance. In the present study, the frequencies of isolated +8 in relation to gender, age, previous treatment with chemo- or radiotherapy, and morphologic subtype were ascertained in published, as well as in our own unpublished, cases of acute myeloid leukemia (AML; n=4,246), myelodysplastic syndromes (MDS; n=1,817), and chronic myeloproliferative disorders (MPD; n=530). The frequencies of +8 were higher in MDS and MPD than in AML (7.5% vs. 5.6%; P<0.01) and varied among the morphologic subtypes of AML and MDS (P<0.001 and P<0.05, respectively). Trisomy 8 was more common in women than in men with MPD (11% vs. 5.1%; P<0.05). Furthermore, the frequencies of +8 were higher in de novo AML and MDS than in treatment-related cases (6.0% vs. 2.8%; P<0.01 and 8.6% vs. 1.5%; P<0.001, respectively). The incidence also varied significantly with age in AML (P<0.001), being more common in elderly patients. Although the causes for this frequency heterogeneity remain to be elucidated, possible explanations may include different environmental exposures affecting the origin of +8 in AML, MDS, and MPD and the presence of different underlying cryptic primary aberrations.

Paired multiplex reverse-transcriptase polymerase chain reaction (PMRT-PCR) analysis as a rapid and accurate diagnostic tool for the detection of MLL fusion genes in hematologic malignancies

The MLL gene in chromosome band 11q23 is frequently rearranged in acute lymphoblastic and acute myeloid leukemias. To date, more than 50 different chromosomal regions are known to participate in translocations involving 11q23, many of which affect MLL. The pathogenetically important outcome of these rearrangements is most likely the creation of a fusion gene consisting of the 5' part of the MLL gene and the 3' end of the partner gene. Although abnormalities of the MLL gene as such are generally associated with poor survival, recent data suggest that the prognostic impact varies among the different fusion genes generated. Hence, detection of the specific chimeric gene produced is important for proper prognostication and clinical decision making. We have developed a paired multiplex reverse-transcriptase polymerase chain reaction analysis to facilitate a rapid and accurate detection of the most frequent MLL fusion genes in adult and childhood acute leukemias. To increase the specificity, two sets of primers were designed for each fusion gene, and these paired primer sets were run in parallel in two separate multiplex one-step PCR reactions. Using the described protocol, we were able to amplify successfully, in one single assay, the six clinically relevant fusion genes generated by the t(4;11)(q21;q23) [MLL/AF4], t(6;11)(q27;q23) [MLL/AF6], t(9;11)(p21-22;q23) [MLL/AF9], t(10;11)(p11-13;q23) [MLL/AF10], t(11;19)(q23;p13.1) [MLL/ELL], and t(11;19)(q23; p13.3) [MLL/ENL] in cell lines, as well as in patient material.

Isodicentric 7p, idic(7)(q11.2), in acute myeloid leukemia associated with older age and favorable response to induction chemotherapy: a new clinical entity?

Three adult de novo acute myeloid leukemias (AML M1, M2, and M4) with an isochromosome 7p are presented. No additional abnormalities were detected by G-band and multicolor, using combined binary ratio labeling, fluorescence in situ hybridization (FISH) analyses, indicating that the i(7p) was the sole, i.e., the primary, chromosomal aberration. Although the patients were elderly--68, 72, and 78 years old--they all responded very well to chemotherapy, achieving complete remission lasting more than a year. Further FISH analyses, using painting, centromeric, as well as 7q11.2-specific YAC probes, revealed that the i(7p) contained two centromeres and that the breakpoints were located in 7q11.2. Thus, the abnormality should formally be designated idic(7)(q11.2). The detailed mapping disclosed a breakpoint heterogeneity, with the breaks in 7q11.2 varying among the cases, being at least 1,310 kb apart. Furthermore, the breakpoints also differed within one of the cases, being located on both the proximal and the distal side of the most centromeric probe used. Based on our three patients, as well as on a previously reported 82-year-old patient with AML M2 and idic(7)(q11) as the only chromosomal change, we suggest that this abnormality, as the sole anomaly, is associated with AML in elderly patients who display a good response to induction chemotherapy and, hence, have a favorable prognosis. Furthermore, the heterogeneous breakpoints in 7q11.2 suggest that the important functional outcome of the idic(7)(q11.2) is the genomic imbalance incurred, i.e., gain of 7p and loss of 7q material, rather than a rearrangement of a specific gene.

Fusion of the MORF and CBP genes in acute myeloid leukemia with the t(10;16)(q22;p13)

The CBP gene at 16p13 fuses to MOZ and MLL as a result of the t(8;16)(p11;p13) in acute (myelo)monocytic leukemias (AML M4/M5) and the t(11;16)(q23;p13) in treatment-related AML, respectively. We show here that a novel t(10;16)(q22;p13) in a childhood AML M5a leads to a MORF-CBP chimera. RT-PCR using MORF forward and CBP reverse primers amplified a MORF-CBP fusion in which nucleotide 3103 of MORF was fused in-frame with nucleotide 284 of CBP. Nested RT-PCR with CBP forward and MORF reverse primers generated a CBP-MORF transcript in which nucleotide 283 of CBP was fused in-frame with nucleotide 3104 of MORF. Genomic analyses revealed that the breaks were close to Alu elements in intron 16 of MORF and intron 2 of CBP and that duplications had occurred near the breakpoints. A database search using MORF cDNA enabled us to construct an exon-intron map of the MORF gene. The MORF-CBP protein retains the zinc fingers, two nuclear localization signals, the histone acetyltransferase (HAT) domain, a portion of the acidic domain of MORF and the CBP protein downstream of codon 29. Thus, the part of CBP encoding the RARA-binding domain, the CREB-binding domain, the three Cys/His-rich regions, the bromodomain, the HAT domain and the Glu-rich domains is present. In the reciprocal CBP-MORF, part of the acidic domain and the C-terminal Ser- and Met-rich regions of MORF are likely to be driven by the CBP promoter. Since both fusion transcripts were present, their exact role in the leukemogenic process remains to be elucidated.

RT-PCR analysis of the MOZ-CBP and CBP-MOZ chimeric transcripts in acute myeloid leukemias with t(8;16)(p11;p13)

The translocation t(8;16)(p11;p13) is associated with a subtype of acute monocytic leukemia (AML M5) characterized morphologically by erythrophagocytosis and clinically by a poor prognosis. The t(8;16) fuses the MOZ gene from 8p11 with the CBP (also named CREBBP) gene from 16p13. Previously published studies of MOZ and CBP rearrangements in t(8;16)-positive AML have used fluorescence in situ hybridization and Southern blot methodologies, whereas attempts to amplify and to analyze further the chimeric MOZ-CBP and CBP-MOZ transcripts by means of reverse transcriptase-polymerase chain reaction (RT-PCR) have largely been unsuccessful. In the only t(8;16) that has been described at the sequence level using RT-PCR, the CBP-MOZ fusion was found to be out-of-frame, suggesting that the reciprocal MOZ-CBP transcript is the essential one for leukemogenesis. We have developed an RT-PCR strategy that enables us to detect the MOZ-CBP as well as the CBP-MOZ fusions in the two AML M5 with t(8;16)(p11;p13) analyzed. In both leukemias, the combination of a MOZ forward and a CBP reverse primer amplified a strongly expressed 1,128 bp fragment (type I transcript) and a weakly expressed 415 bp fragment (type II transcript). In the type I transcript, nucleotide (nt) 3,745 of MOZ was fused in-frame with nt 284 of CBP, whereas in the type II transcript, nt 3,745 of MOZ was fused out-of-frame with nt 997 of CBP. Nested PCR with a combination of two forward CBP and two reverse MOZ primers amplified CBP-MOZ chimeric transcripts in both cases. Direct sequence analysis showed that nt 283 of CBP was fused in-frame with nt 3,746 of MOZ, that the initiation ATG codon of the CBP gene remained intact, and that there was no mutation or deletion in the part of the CBP gene included in the CBP-MOZ transcript. Thus, the data we present are not informative with regard to the question whether it is the MOZ-CBP or the CBP-MOZ transcript that is leukemogenic. The present RT-PCR method may be of value for rapid identification of the t(8;16) and also for further molecular genetic studies of the two fusion transcripts and their roles in leukemogenesis.

Granulocytic sarcomas in body cavities in childhood acute myeloid leukemias with 11q23/MLL rearrangements

Three childhood acute monoblastic leukemias (AML M5) with granulocytic sarcomas (GSs) are described. All displayed 11q23/MLL abnormalities, t(9;11)(p22;q23) in two cases and t(11;17)(q23;q21) in one case, constituting around 20% of all 11q23-positive AML cytogenetically investigated in our department. Two of the patients had GS in multiple locations, and all three had abdominal GS. In two of them, t(9;11)-positive GS was diagnosed prior to the diagnosis of AML. Fourteen (1.9%) of 752 published AML cases with 11q23 aberrations have had GS, either as a presenting feature or during disease progression. The incidence of GS has varied significantly (P < 0.05) between children (3.8%) and adults (0.8%). The most common AML subtype has been AML M5 ( approximately 75%) and the most frequent GS sites have been the skin, abdomen, orbit, and thorax. Considering the possibility of underreporting of GS in published cases and the relatively high frequency in our own series, we believe that 11q23/MLL rearrangements may predispose to GS development. Although extramedullary infiltrates in the skin are known to be frequent in cases of AML M5, which is often associated with 11q23 aberrations, the present findings indicate that GS in the abdomen, orbit, and thorax may also be common, especially in pediatric AML. Thus, the possibility of 11q23/MLL-positive GS should be suspected when tumors of uncertain derivation occur in these sites. Finally, the identification of 11q23/MLL abnormalities in GSs in two patients without overt AML underscores the importance of using cytogenetic and molecular genetic investigations as a diagnostic approach in the evaluation of tumorous lesions of unknown origin. Genes Chromosomes Cancer 27:136-142, 2000.

Isochromosome 17q in blast crisis of chronic myeloid leukemia and in other hematologic malignancies is the result of clustered breakpoints in 17p11 and is not associated with coding TP53 mutations

An isochromosome of the long arm of chromosome 17, i(17q), is the most frequent genetic abnormality observed during the disease progression of Philadelphia chromosome-positive chronic myeloid leukemia (CML), and has been described as the sole anomaly in various other hematologic malignancies. The i(17q) hence plays a presumably important pathogenetic role both in leukemia development and progression. This notwithstanding, the molecular consequences of this abnormality have not been investigated in detail. We have analyzed 21 hematologic malignancies (8 CML in blast crisis, 8 myelodysplastic syndromes [MDS], 2 acute myeloid leukemias, 2 chronic lymphocytic leukemias, and 1 acute lymphoblastic leukemia) with i(17q) by fluorescence in situ hybridization (FISH). Using a yeast artificial chromosome (YAC) contig, derived from the short arm of chromosome 17, all cases were shown to have a breakpoint in 17p. In 12 cases, the breaks occurred within the Smith-Magenis Syndrome (SMS) common deletion region in 17p11, a gene-rich region which is genetically unstable. In 10 of these 12 cases, we were able to further map the breakpoints to specific markers localized within a single YAC clone. Six other cases showed breakpoints located proximally to the SMS common deletion region, but still within 17p11, and yet another case had a breakpoint distal to this region. Furthermore, using chromosome 17 centromere-specific probes, it could be shown that the majority of the i(17q) chromosomes (11 of 15 investigated cases) were dicentric, ie, they contained two centromeres, strongly suggesting that i(17q) is formed through an intrachromosomal recombination event, and also implicating that the i(17q), in a formal sense, should be designated idic(17)(p11). Because i(17q) formation results in loss of 17p material, potentially uncovering the effect of a tumor suppressor on the remaining 17p, the occurrence of TP53 mutations was studied in 17 cases by sequencing the entire coding region. In 16 cases, no TP53 mutations were found, whereas one MDS displayed a homozygous deletion of TP53. Thus, our data suggest that there is no association between i(17q) and coding TP53 mutations, and that another tumor suppressor gene(s), located in proximity of the SMS common deletion region, or in a more distal location, is of pathogenetic importance in i(17q)-associated leukemia.

Cytogenetic polyclonality in hematologic malignancies

The present study was undertaken to ascertain the frequency of cytogenetic polyclonality in various hematologic malignancies and to investigate whether morphologic subgroup, age, gender, or previous genotoxic exposure influences the incidence. Among 2,243 cytogenetically investigated hematologic malignancies, 10 acute myeloid leukemias (AML), 5 myelodysplastic syndromes (MDS), 2 acute lymphoblastic leukemias (ALL), 1 acute undifferentiated leukemia (AUL), 1 atypical Philadelphia chromosome-negative (Ph-) chronic myeloid leukemia (CML), 1 chronic myeloproliferative disorder (CMD), and 1 chronic lymphoproliferative disorder (CLD) with karyotypically unrelated clones were identified, constituting 2.6% of AML, 1.6% of MDS, 0.8% of ALL, 13% of AUL, 9.1% of Ph- CML, 1.5% of CMD, and 2.8% of CLD with chromosomal abnormalities. In contrast to the cytogenetic features, the X-inactivation pattern was monoclonal in the two informative female patients that could be investigated. Among 17,733 karyotypically aberrant published cases surveyed, significant frequency differences (P < 0.001) were discerned: 1.7% of 6,526 AML, 3.4% of 2,391 MDS, 0.4% of 1,920 Ph+ CML, 2.9% of 856 CMD, 0.9% of 4,226 ALL, and 5.8% of 1,814 CLD displayed unrelated clones. The incidence of cytogenetic polyclonality did not differ significantly among the MDS, CMD, or ALL subgroups, between males and females, between children (< 16 years) and adults, or between B- and T-cell ALL, whereas the frequencies varied among the AML FAB types (P < 0.05), among the different CLD entities (P < 0.001), and between B- and T-cell CLD (P < 0.001). Furthermore, the incidence was higher in therapy-related AML and MDS than in de novo AML and MDS (P < 0.001 and P < 0.01, respectively).

BCR/ABL-negative chronic myeloid leukemia with ETV6/ABL fusion

A BCR/ABL-negative chronic myeloid leukemia (CML) with t(12;14) (p12;q11-13) as the sole chromosomal abnormality was investigated by fluorescence in situ hybridization (FISH), which disclosed a cryptic insertion of ETV6 (previously called TEL), located at 12p12, into ABL at chromosome band 9q34. ETV6/ABL fusion was confirmed by RT-PCR, revealing that the first five exons of ETV6 were fused in frame with ABL at exon 2. Wild-type ETV6 was expressed, in accordance with the FISH results showing no deletion of the second ETV6 allele. ETV6/ABL chimeric transcripts have previously been reported in acute leukemias, but never before in CML. The present case suggests that ETV6/ABL positivity may constitute a new genetic subgroup of BCR-negative CML.

Poor survival in t(8;21) (q22;q22)-associated acute myeloid leukaemia with leukocytosis

Twenty-nine consecutive cases with a t(8;21)(q22;q22) in the bone marrow (BM) karyotype were retrospectively studied concerning clinical, morphological and cytogenetic data. All had been diagnosed as acute myeloid leukaemia (AML), 27 FAB subtype M2 and two M1, comprising 5% of all cytogenetically analysed AML during 18 yr. Auer rods were the most consistent t(8;21)-associated morphological finding and were demonstrated in 92% of the reviewed BM specimens, whereas BM eosinophilia was seen in only 24%. The median age was 53 yr, and 30% of the patients were > 60 yr old. Twenty-four patients had received induction chemotherapy; 22 of these (91%) entered a complete remission (CR). The median survival time in treated patients was 18 months. Leukocytosis at diagnosis (> or = 20 x 10(9)/1) was significantly (p = 0.01) associated with shorter survival time. All four children are still in first CR after 9-80 months. Seven cases (25%) developed granulocytic sarcomas, discovered either at diagnosis (n = 4) or at first relapse (n = 3). Secondary chromosome abnormalities were found in 62% of the cases, most often loss of a sex chromosome. The presence of such secondary aberrations did not correlate with any morphological or clinical characteristics, including survival. This first Scandinavian study of AML with t(8;21) corroborates the previous findings that these AMLs are characterized by distinct morphological features, a high frequency of CR and a striking tendency to develop extramedullary leukaemic manifestations. Leukocytosis at diagnosis indicates a less favourable prognosis.

Expression patterns of the human sarcoma-associated genes FUS and EWS and the genomic structure of FUS

FUS (TLS) was first identified as the 5'-part of a fusion gene with CHOP (GADD153, DDIT3) in myxoid liposarcomas with t(12; 16)(q13; p11). Homologies were found with the EWS oncogene, which is rearranged in Ewing sarcomas and other neoplasias. The genomic structure of FUS shows extensive similarities with that of EWS, but the exon/intron structures differ in the 5' parts, and overall FUS is smaller than EWS. Exon 3 of FUS corresponds to exons 3 and 4 in EWS. FUS exons 4-6 correspond to EWS exons 5-8. Exons 7 to 15 of FUS are very similar to those in EWS, although the EWS exons are larger than the corresponding FUS exons. FUS and EWS were expressed in all tissues investigated. The transcripts were stable within the 160-min half-life experiments. No or little variation in FUS or EWS expression was seen when resting lymphocytes were activated. These observations indicate that FUS and EWS belong to the housekeeping type of genes. This view is supported by the presence of the housekeeping gene type of promoter region in both genes.

Abberant cytogenetic evolution pattern of Philadelphia-positive chronic myeloid leukemia treated with interferon-alpha

The cytogenetic evolution of 32 Philadelphia (Ph)-positive chronic myeloid leukemias (CML) receiving interferon-alpha (IFN-alpha) therapy was compared to the patterns in untreated CML and cases treated with busulfan (Bu), hydroxyurea (Hy), and allogeneic bone marrow transplantation (BMT). Half of the CML receiving IFN-alpha had at least one of the well-known major or minor route aberrations whereas 16 cases displayed unusual secondary abnormalities, of which only del(7p) and del(13q) were recurrent; a frequency significantly higher than in CML without therapy or after Bu and Hy treatment (P < 0.001) but similar to the one found post-BMT. The incidence of cases with cytogenetically divergent subclones, ie cell populations with unrelated aberrations in addition to the t(9;22), was also higher in the IFN-alpha group compared to the untreated, Bu and Hy groups (P < 0.01) but similar to the post-BMT group. Finally, 14 of the 32 IFN-alpha-treated CML displayed cytogenetic evolution already during the chronic phase; again a higher incidence than in the untreated, Bu and Hy groups (P < 0.001) but not different from the post-BMT group. These findings strongly indicate that IFN-alpha, directly or indirectly, can induce clones with aberrant chromosomal evolution patterns to evolve and proliferate, but the mechanisms underlying these cytogenetic peculiarities remain to be elucidated.

t(3;21)(q26;q22) with AML1 rearrangement in a de novo childhood acute monoblastic leukaemia

t(3;21)(q26;q22) is a recurrent chromosomal abnormality in Philadelphia-positive chronic myeloid leukaemia in blast crisis and in treatment-related myelodysplastic syndrome and acute myeloid leukaemia. The molecular consequences of the t(3;21) are presently being unravelled; various transcripts between the AML1 gene in 21q22 and several unrelated genes, i.e. EAP, EVI1 and MDS1, in 3q26 are generated, resulting in the formation of a chimaeric transcription factor. The t(3;21) has only rarely been described in de novo leukaemias and never before in an acute leukaemia in a child. We here present the clinical, cytogenetic and molecular genetic findings in a boy with a de novo acute monoblastic leukaemia with t(3;21)(q26;q22) and AML1 rearrangement.

Standpoint on imprinting of BCR and ABL

Cytogenetic studies of Ph-positive leukemic patients and their parents have indicated that chromosome 22 involved in the formation of the t(9;22) is of maternal origin, whereas chromosome 9 is preferentially of paternal origin. These data have suggested that the two genes BCR and ABL, which become fused through the translocation, might be imprinted, ie expressed in a parental-specific manner. Recent molecular genetic studies however, have shown that BCR and ABL are expressed on both alleles and that the maternal and paternal ABL genes contribute equally often to the BCR-ABL fusion messenger. The findings make imprinting of these genes unlikely as an explanatory model and necessitate a combined cytogenetic and molecular genetic study.

Regional localization and developmental expression of the BCR gene in rodent brain

The BCR gene is implicated in the development of Ph-positive leukemia through its fusion with the nonreceptor tyrosine kinase gene ABL. The normal 160 kDa Bcr protein has several functional domains, and recently one specific role for Bcr was established in the regulation of respiratory burst activity in white blood cells. Bcr expression levels are relatively constant throughout mouse development until adulthood in brain and in hematopoietic tissues, a pattern that is distinctly different from that of the functionally related n-chimerin gene. In the present study, RNA in situ hybridization was used to explore the normal cellular function of Bcr in rodent brain and hematopoietic organs. The data pinpoint the high bcr expression in the brain to the hippocampal pyramidal cell layer and the dentate gyrus, and to the piriform cortex and the olfactory nuclei, reflecting a potentially interesting function for Bcr in these highly specialized brain regions.

Fusion of the FUS gene with ERG in acute myeloid leukemia with t(16;21)(p11;q22)

It has been shown that the gene ERG in 21q22 is rearranged in the t(16;21)(p11;q22) associated with acute myeloid leukemia (AML). ERG is a member of the ETS gene family and is fused with EWS in a subset of Ewing's sarcomas. EWS in 22q12 has a very high homology with FUS (also called TLS) in 16p11; the latter gene is rearranged in the t(12;16)(q13;p11) that characterizes myxoid liposarcoma. To investigate whether FUS is involved in the t(16;21) of AML, we used the Southern blot technique and polymerase chain reaction (PCR) to examine the bone marrow of a 3-year-old boy with a t(16;21)(p11;q22)-positive AML. Hybridization of Southern blot filters containing digested DNA with probes for FUS and ERG showed both germline and aberrant fragments. Using specific primers for the 5' part of FUS and the 3' part of ERG, we amplified a 4.4 kb genomic FUS/ERG DNA fragment from the leukemic sample. In a second PCR experiment, in which we used primers upstream of the 5' part of ERG and downstream of the 3' part of FUS, a 5.6 kb fragment was amplified. Blotting and hybridization with specific probes for FUS and ERG revealed that the amplified fragments consisted of FUS/ERG and ERG/FUS hybrid DNA. Both PCR fragments, when used as probes, detected germline ERG and FUS as well as aberrant fragments on Southern blot filters. The results suggest that the t(16;21) in AML leads to rearrangement and fusion of the FUS and ERG genes.(ABSTRACT TRUNCATED AT 250 WORDS)

IFN-alpha treatment of p190 bcr abl transgenic mice

Interferon-alfa (IFN-alpha) is one of the most effective drugs in the treatment of chronic myeloid leukemia (CML). Recently, IFN-alpha has also been tried in the treatment of Ph-positive acute lymphoid leukemia (ALL), a disease in part sharing the same molecular genetic lesion as CML, namely a BCR/ABL fusion gene. In the present study we analyzed the effect of IFN-alpha (rHuIFN-alphaA/D) on a mouse model for Ph-positive ALL - mice transgenic for the P190 BCR/ABL fusion gene. IFN-alpha treatment was started in the early leukemic phase and continued throughout the course of the disease in eight transgenic animals. No prolonged survival or altered disease pattern with regard to the development of leukemia and/or lymphoma was observed. We conclude that IFN-alpha, at least in a transgenic setting, does not interfere with the leukemogenic process induced by the P190 BCR/ABL fusion gene.

No evidence for genomic imprinting of the human BCR gene

Chronic myeloid leukemias and 5% to 20% of acute lymphoid leukemias are characterized by the Philadelphia chromosome, a reciprocal chromosomal translocation, t(9;22)(q34;q11), generating BCR-ABL and ABL-BCR fusion genes. Cytogenetic studies have recently shown a preferential involvement of the paternally derived chromosome 9 and the maternally derived chromosome 22 in this translocation, indicating that imprinting might be involved in the formation or selection of the translocation. In this study, we have identified a BamHI polymorphism in the coding region of BCR exon 1, allowing us to investigate whether both BCR alleles are transcribed. By using a reverse transcriptase-polymerase chain reaction assay, we show that both BCR alleles are expressed in the peripheral blood cells of normal individuals.

Cellular interactions of CRKL, and SH2-SH3 adaptor protein

Chronic myelogenous leukemia is characterized by a specific chromosomal translocation, t(9;22), in which the ABL protooncogene and the BCR gene become juxtaposed. The chimeric BCR/ABL gene produces a P210 fusion protein with deregulated tyrosine kinase activity. We have recently isolated a complementary DNA, CRKL, which could code for an adaptor protein consisting of one SH2 and two SH3 domains and lacking any catalytic domain. In the current study, we show that CRKL is highly phosphorylated in the chronic myelogenous leukemia cell line K562 and that it is a substrate for the p210 BCR/ABL and p145 ABL kinases. BCR/ABL and ABL are coimmunoprecipitated with CRKL in vivo, demonstrating that relatively stable complexes are formed. In addition, the nucleotide exchange factor mSOS1 was found to be coimmunoprecipitated with CRKL. These findings establish a putative signal transduction pathway way through which BCR/ABL mediates its oncogenic activity.

Molecular analysis of simple variant translocations in acute promyelocytic leukemia

The primary cytogenetic abnormality in acute promyelocytic leukemia (APL; FAB M3) is a reciprocal translocation, t(15;17)(q22;q12), which serves to fuse the PML gene on chromosome 15 to the retinoic acid receptor alpha (RARA) gene on chromosome 17. A PML-RARA fusion message transcribed from the der(15) is thought to mediate leukemogenesis. Two APL patients with simple variants of this translocation, t(3;15)(q21;q22) and t(X;15)(p11;q22), have previously been reported who lack cytogenetic involvement of chromosome 17, although their breakpoint positions on chromosome 15 still suggest the involvement of the PML gene. Here we report on a combined analysis by molecular genetics and in situ hybridization of these two patients, in which we wanted to determine whether the PML gene has alternative fusion partners or whether cryptic rearrangement of the RARA locus has occurred instead. A cryptic involvement of RARA was demonstrated in both patients by a combination of Southern analysis, reverse transcription coupled to PCR (RT-PCR), and fluorescence in situ hybridization. The results indicate an absolute requirement for the rearrangement of the RARA gene in the pathogenesis of APL and underline the importance of RARA during normal myeloid differentiation.

CRK proto-oncogene maps to human chromosome band 17p13

A genomic DNA fragment, isolated from a human phage library using a chicken crk cDNA probe, was shown to derive from the human CRK locus. We have used fluorescent in situ hybridization (FISH) to map CRK distal in chromosome band 17p13, a region which demonstrates frequent deletion or loss of heterozygosity in a wide range of human cancers.

Clinical impact of breakpoint position within M-bcr in chronic myeloid leukemia

We have analyzed the M-bcr breakpoint position in 133 Philadelphia-positive chronic myeloid leukemia patients and correlated the findings with clinical, hematologic, and cytogenetic data. We also investigated the splicing pattern of the BCR-ABL mRNA in 30 patients, using reverse transcriptase PCR. No statistically significant differences were found between breakpoint position within M-bcr and clinical parameters at diagnosis, the karyotypic evolution pattern, or the leukemic phenotype during blast crisis. Furthermore, the breakpoint position within M-bcr did not correlate with the duration of chronic phase or survival time. When the splicing pattern of the BCR-ABL mRNA was compared with the results of the genomic breakpoint mapping, it was found that approximately 60% (8/14) of the patients with a 5' break expressed b2a2 fusion mRNA, whereas all patients (10/10) with a 3' break expressed b3a2 BCR-ABL mRNA.

Diagnosis of acute promyelocytic leukaemia by RT-PCR: detection of PML-RARA and RARA-PML fusion transcripts

Acute promyelocytic leukaemia (APL; AML M3) is identified by a unique t(15;17) translocation which fuses the PML gene to the retinoic acid receptor alpha gene (RARA). Reverse transcription coupled with the polymerase chain reaction (RT-PCR) has been used to develop a diagnostic test for APL based on the PML-RARA fusion message. Separate PCR assays were designed to amplify either PML-RARA (15q+ derived) or RARA-PML (17q- derived) chimaeric transcripts. PML-RARA transcripts were detected in every case from a series of 18 APL patients with cytogenetically confirmed t(15;17) translocations, whereas RARA-PML messages were detected in only 67% (12/18) of these patients. This suggests that it is the 15q+ derivative which mediates leukaemogenesis. Furthermore the PCR approach (or Southern analysis) may be used to identify in which of the alternative PML introns the breakpoint occurs; 52% of cases (15/29 patients) utilize a 5' PML intron and 48% the 3' intron (14/29 cases). Neither the choice of PML intron nor the expression of the 17q- derivative could be correlated with the microgranular variant of APL (M3V), overall survival rate, age, sex or presence of coagulopathy. Finally, the fusion message is undetectable in five remission samples. This indicates a possible use for RT-PCR in monitoring remission patients for evidence of relapse.

Rearrangement of the transcription factor gene CHOP in myxoid liposarcomas with t(12;16)(q13;p11)

Most myxoid liposarcomas (MLS) are characterized cytogenetically by a t(12;16)(q13;p11). It is reasonable to assume that this translocation corresponds to the consistent rearrangement of one or two genes in 12q13 and/or 16p11, and that the loci thus affected are important in the normal control of fat cell differentiation and proliferation. We have used Southern blot technique to test whether a gene of the CCAAT/enhancer binding protein (C/EBP) family, CHOP, which maps to 12q13 and is assumed to be involved in adipocyte differentiation, could be the 12q gene in question. Using a cDNA probe that spans the CHOP coding region, we detected one rearranged and one wild type allele in nine of nine MLS with t(12;16). Using PCR generated, site-specific probes corresponding to the non-coding exons 1 and 2 and intron 2 of CHOP, rearrangements in five of seven tumors mapped to the 2.4 and 1.6 kbp PstI fragments that contain the first two exons and introns of the gene and the upstream promoter region. In contrast to the findings in MLS, no tumor without a t(12;16) exhibited aberrant CHOP restriction digest patterns. These tumors included one highly differentiated liposarcoma with abnormal karyotype but no involvement of 12q13, seven lipomas with various cytogenetic aberrations of 12q13-15, two uterine leiomyomas with t(12;14) (q14-15;q23-24), and one hemangiopericytoma and one chondroma, both of which also had 12q13 changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular analysis of Philadelphia-positive childhood chronic myeloid leukemia

The breakpoints in chromosome 22 were determined in five children with Philadelphia-positive chronic myeloid leukemia. All had rearrangements within the major breakpoint cluster region (M-bcr). Four patients had breakpoints in the 5' region of M-bcr (zones 1-3), whereas one had a rearrangement in the 3' region (zone 4). The patient with the 3' rearrangement was the only one to develop a lymphoid blast crisis; he also had a substantially longer survival (102 months) than the others (11-54 months).

Acute myelomonocytic leukemia with inv(16)(p13q22) complicating Philadelphia chromosome positive chronic myeloid leukemia

The reciprocal translocation (9;22)(q34;q11) is highly characteristic of chronic myeloid leukemia (CML) and the pericentric inversion inv(16)(p13q22) is almost only found in acute nonlymphocytic leukemia of the myelomonocytic subtype (ANLL M4). Only twice before have an inv(16) and a t(9;22) been found in the same cells, and both times the patients seemed to have de novo ANLL M4. We describe the case of a 21-year-old man who in July 1986 presented with a clinically and hematologically classic chronic phase CML. Treatment with busulfan led to no improvement; instead in September 1986 he developed blast crisis with ANLL M4Eo morphology. He was now cytogenetically examined and the karyotype 45,X,-Y,t(9;22)(q34;q11),inv(16)(p13q22) was found. Southern blot analysis of the bone marrow DNA sampled at this time revealed a standard rearrangement in the 3' end of the M-bcr. Intensive cytostatic treatment caused cytopenia followed by complete hematologic, clinical, and cytogenetic reversal to chronic phase CML, so that in January 1987 the bone marrow karyotype was 46,XY,t(9;22)(q34;q11). Persistent splenomegaly was treated with splenectomy, and a chloroma of the skin was removed by irradiation. In March 1987 he received an allogeneic bone marrow transplant. Since then his only medical problem has been mild graft-versus-host disease; he is well and is working full time as a blacksmith.

An EcoRI polymorphism at the insulin receptor locus on a fragment comprising exons 4 to 8

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[Molecular genetics methods discovering the mechanisms of neoplasm etiology]

The rapid advance in our understanding of cancer biology during the past decade, as exemplified by the discovery of oncogenes and tumour suppressor genes and their interactions in tumourigenesis, has revolutionized cancer research. This rapid progress has largely been due to the use of molecular genetics techniques. However, despite the wealth of available information as to the genetic basis of carcinogenesis, its clinical applicability remains limited. The review is a summary of the general principles and methods currently used to detect genetic alterations in neoplastic cells, with special emphasis on clinical applications.

Remarkably long survival of a patient with Ph1-positive chronic myeloid leukemia and 5' bcr rearrangement

Chronic myeloid leukemia (CML) was diagnosed in a 19-year-old man in 1961, and the disease remained in chronic phase, with occasional exacerbations, for 27 years. In 1976, when the first cytogenetic analysis was performed, t(9;22)(q34;q11) was found as the sole abnormality in all mitoses. During accelerated phase in 1988, a second cytogenetic investigation showed the karyotype 45,XY,t(9;22)(q34;q11),-15,-17,+der(15) t(15;17)(p13;q11). Molecular analysis revealed a rearrangement in the 5' end of the major breakpoint cluster region (M-bcr). With the case presented here, sublocalization of the bcr breakpoint has now been undertaken in altogether five CML patients with extremely long survival. It is noteworthy that in all these cases the chromosome 22 breakpoint was located in the 5' region of the M-bcr.