Significance Analysis of Microarrays (SAM) Offers Clues to Differences between the Genomes of Adult Philadelphia Positive ALL and the Lymphoid Blast Transformation of CML

Philadelphia positive malignant disorders are a clinically divergent group of leukemias. These include chronic myeloid leukemia (CML) and de novo acute Philadelphia positive (Ph(+)) leukemia of both myeloid, and lymphoid origin. Recent whole genome screening of Ph(+)ALL in both children and adults identified an almost obligatory cryptic loss of Ikaros, required for the normal B cell maturation. Although similar losses were found in lymphoid blast crisis the genetic background of the transformation in CML is still poorly defined. We used Significance Analysis of Microarrays (SAM) to analyze comparative genomic hybridization (aCGH) data from 30 CML (10 each of chronic phase, myeloid and lymphoid blast stage), 10 Ph(+)ALL adult patients and 10 disease free controls and were able to: (a) discriminate between the genomes of lymphoid and myeloid blast cells and (b) identify differences in the genome profile of de novo Ph(+)ALL and lymphoid blast transformation of CML (BC/L). Furthermore we were able to distinguish a sub group of Ph(+) ALL characterized by gains in chromosome 9 and recurrent losses at several other genome sites offering genetic evidence for the clinical heterogeneity. The significance of these results is that they not only offer clues regarding the pathogenesis of Ph(+) disorders and highlight the potential clinical implications of a set of probes but also demonstrates what SAM can offer for the analysis of genome data.

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Are CML Lymphoid Blast Crisis and Ph Positive ALL Genomically Indistinguishable?

Blood ◽

10.1182/blood.v116.21.4464.4464 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4464-4464

Author(s):

Colin Grace ◽

Elisabeth P Nacheva

Keyword(s):

Tyrosine Kinase ◽

Dna Sequences ◽

Acute Leukaemia ◽

De Novo ◽

Conflicts Of Interest ◽

Hot Spot ◽

Blast Crisis ◽

Disease Stage ◽

Blast Transformation ◽

Significance Analysis

Abstract Abstract 4464 Philadelphia positive malignant disorders are a clinically divergent group of hemoblastoses with a unique identifying feature, the BCR/ABL1 fusion gene, usually resulting from the chromosome rearrangement t(9;22)(q34;q11) or its variants, that leads to constitutive expression of an aberrant tyrosine kinase. These include chronic myeloid leukaemia (CML) and de novo acute leukaemia of both myeloid Ph(+)AML and lymphoid origin Ph(+)ALL. The latter two disorders are clinically aggressive and therapy challenging even in the era of the powerful tyrosine kinase inhibitors. CML is a multistage progressive disease, which if untreated, inevitably ends as fatal acute leukaemia, either myeloid or lymphoid. The latter is often thought to be indistinguishable from Ph(+)ALL, the most common type of ALL in adults. We have identified DNA sequences the imbalances of which appear to be significantly associated with the disease stage and lineage origin in CML and Ph(+)ALL samples. We used array CGH at a resolution of ~2kb to explore hot spot regions obtained from 102 patient samples comprising 92 CML and controls together with 10 Ph(+)ALL and show how Significance Analysis of Microarrays (1) can be used to identify differences in the genome profile of de novo Ph(+)ALL and lymphoid blast transformation of CML. We show that lymphoid blast crisis CML differs significantly from Ph(+)ALL not only due to the presence of 9p deletions but also due to genomic gains in other chromosomes. Furthermore we identify a sub group of Ph(+)ALL with a distinctive genomic profile. Having identified genome regions of potential interest, ranked in order of significance, out of the 100's of thousands of array results, it is then a challenge to design further experiments to evaluate their contribution to the biology of the BCR/ABL positive disease. 1 Tusher V, Tibshirani R, Chu G: Significance analysis of microarrays applied to the ionizing radiation response. Proc Natl Acad Sci U S A 98:5116-5121 (2001). Disclosures: No relevant conflicts of interest to declare.

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RUNX1 DNA-binding mutations and RUNX1-PRDM16 cryptic fusions in BCR-ABL+ leukemias are frequently associated with secondary trisomy 21 and may contribute to clonal evolution and imatinib resistance

Blood ◽

10.1182/blood-2007-07-102533 ◽

2008 ◽

Vol 111 (7) ◽

pp. 3735-3741 ◽

Cited By ~ 44

Author(s):

Catherine Roche-Lestienne ◽

Lauréline Deluche ◽

Sélim Corm ◽

Isabelle Tigaud ◽

Sami Joha ◽

...

Keyword(s):

Dna Binding ◽

High Frequency ◽

Trisomy 21 ◽

De Novo ◽

Blast Crisis ◽

Clonal Evolution ◽

Chronic Phase ◽

Chromosome 21 ◽

Imatinib Resistance ◽

Molecular Abnormalities

Abstract Acquired molecular abnormalities (mutations or chromosomal translocations) of the RUNX1 transcription factor gene are frequent in acute myeloblastic leukemias (AMLs) and in therapy-related myelodysplastic syndromes, but rarely in acute lymphoblastic leukemias (ALLs) and chronic myelogenous leukemias (CMLs). Among 18 BCR-ABL+ leukemias presenting acquired trisomy of chromosome 21, we report a high frequency (33%) of recurrent point mutations (4 in myeloid blast crisis [BC] CML and one in chronic phase CML) within the DNA-binding region of RUNX1. We did not found any mutation in de novo BCR-ABL+ ALLs or lymphoid BC CML. Emergence of the RUNX1 mutations was detected at diagnosis or before the acquisition of trisomy 21 during disease progression. In addition, we also report a high frequency of cryptic chromosomal RUNX1 translocation to a novel recently described gene partner, PRDM16 on chromosome 1p36, for 3 (21.4%) of 14 investigated patients: 2 myeloid BC CMLs and, for the first time, 1 therapy-related BCR-ABL+ ALL. Two patients presented both RUNX1 mutations and RUNX1-PRDM16 fusion. These events are associated with a short survival and support the concept of a cooperative effect of BCR-ABL with molecular RUNX1 abnormalities on the differentiation arrest phenotype observed during progression of CML and in BCR-ABL+ ALL.

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Basophils (Bsp-1+) derive from the leukemic clone in human myeloid leukemias involving the chromosome breakpoint 9q34

Blood ◽

10.1182/blood.v73.3.777.777 ◽

1989 ◽

Vol 73 (3) ◽

pp. 777-781 ◽

Cited By ~ 12

Author(s):

MP Bodger ◽

CM Morris ◽

MA Kennedy ◽

JA Bowen ◽

JM Hilton ◽

...

Keyword(s):

Toluidine Blue ◽

Myeloid Leukemia ◽

Blast Crisis ◽

Interleukin 2 ◽

Philadelphia Chromosome ◽

Chronic Phase ◽

Normal Karyotype ◽

Buffy Coat ◽

Chromosome 9 ◽

Leukemic Clone

Abstract The monoclonal antibody (MoAb) Bsp-1 was used to purify basophilic cells from leukemic blood of five patients with Philadelphia chromosome (Ph′) positive chronic myeloid leukemia (CML) and two patients with acute myeloid leukemia (AML) characterized by the chromosomal translocation t(6;9)(p23;q34). When cultured, Bsp-1 positive cells from all CML and AML patients showed the same clonal karyotype changes observed in diagnostic buffy coat preparations, indicating that the basophilic cells were of leukemic origin. In contrast, T lymphocytes from four of five CML patients cultured in the presence of interleukin- 2 (IL-2) showed a normal karyotype and were therefore not derived from the leukemic clone. Bsp-1 staining correlated with toluidine blue- positive basophils in chronic phase CML and with toluidine blue- negative blast cells expressing an immature myeloid phenotype in blast crisis CML and AML. Chromosome in situ hybridization showed that the ABL oncogene was translocated from chromosome 9 to chromosome 22 in the CML patients but remained on chromosome 9 in the AML patients. These results indicate that the breakpoint at 9q34 in CML is 5′ of ABL, whereas the breakpoint at 9q34 in AML is 3′ of ABL. Field inversion gel electrophoresis showed that the 9q34 breakpoint was not within 200 kb 3′ of ABL in one of the AML patients, nor was there any rearrangement of the PIM oncogene locus at 6p21.

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Detection of derivative 9 deletion by BCR-ABL fluorescence in-situ hybridization signal pattern to evaluate treatment response in CML patients

Archive of oncology ◽

10.2298/aoo0902013p ◽

2009 ◽

Vol 17 (1-2) ◽

pp. 13-18

Author(s):

Beena Patel ◽

Pina Trivedi ◽

Manisha Brahmbhatt ◽

Sarju Gajjar ◽

Ramesh Iyer ◽

...

Keyword(s):

Fusion Gene ◽

Blast Crisis ◽

Chronic Phase ◽

Response To Therapy ◽

Chromosome 9 ◽

Derivative Chromosome ◽

Partial Responder ◽

Signal Pattern ◽

Fish Signal

Background: To evaluate prognostic effect of submicroscopic deletions involving breakage and fusion points of the derivative chromosome 9 and 22 in chronic myeloid leukemia in untreated patients and their follow up samples to correlate with disease outcome. Methods: The study included 78 pretreatment (PT) samples from CML patients and 90 follow-up samples, classified as complete responders (CR, n=33), nonresponders (NR, n =54), and partial responder (PR, n=3) depending on the treatment status of the follow-up samples. Karyotype analysis was performed on metaphases obtained through short term cultures of bone marrow and blood. Detection of BCR-ABL fusion gene was performed using dual color dual fusion (D-FISH) translocation probes. Results: BCR-ABL fusion gene detection by D-FISH showed ABL-BCR deletion on derivative 9 in 47.8% of nonresponders which was higher as compared to pretreatment (11%). Mix D-FISH signal pattern was found in around 20% of pretreatment and non-responder samples. Average interval from chronic phase to blast crisis and accelerated phase was respectively 3.5 and 18 months and accelerated to blast crisis was 16.5 months from the time of diagnosis. The follow-up duration of 31 patients responded to therapy was significantly higher (p=0.0001) as compared to 45 patients who did not respond to therapy. Variant D-FISH signal pattern was seen at the time of diagnosis in patient who responded to therapy as well as those patients who did not respond to therapy. Conclusion: This is the first study from India reporting deletion in ABL, BCR, or ABL-BCR on derivative 9 did not correlate with response to therapy.

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Different Isoforms of the B-Cell Mutator Activation-Induced Cytidine Deaminase (AID) Are Aberrantly Over-Expressed in BCR-ABL1-Positive Acute Lymphoblastic Leukemia (ALL) Patients and Promote Genetic Instability.

Blood ◽

10.1182/blood.v112.11.1497.1497 ◽

2008 ◽

Vol 112 (11) ◽

pp. 1497-1497

Author(s):

Ilaria Iacobucci ◽

Annalisa Lonetti ◽

Anna Ferrari ◽

Simona Soverini ◽

Emanuela Ottaviani ◽

...

Keyword(s):

Genetic Instability ◽

De Novo ◽

Splice Variants ◽

Cytidine Deaminase ◽

Blast Crisis ◽

Chronic Phase ◽

Wild Type ◽

Genome Wide ◽

A Genome ◽

Activation Induced Cytidine Deaminase

Abstract Background: BCR-ABL1-positive ALL is the most frequent and prognostically most unfavorable subtype of adult ALL. The main reason for the poor clinical outcome of BCR-ABL1-positive ALL is genetic instability. However, how normal B-cell precursor cells acquire the genetic changes that lead to transformation and progression has not been completely defined. Activation-induced cytidine deaminase (AID) produces immunediversity by inducing somatic hypermutations and class-switch recombinations in human immunoglobulin genes (Ig). Aim: Since at much lower frequency AID can also target non-Ig genes and may even act as a genome-wide mutator, we investigated whether AID was expressed in BCR-ABL1-positive ALL and in chronic myeloid leukemia (CML) at the time of progression to blast crisis. Patients and methods: We analyzed 61 adult de novo Ph+ ALL patients (pts) and 60 CML pts (chronic phase and myeloid/lymphoid blast crisis). AID cDNA, obtained from bone marrow or peripheral blood, was amplified with two pairs of oligonucleotides, the forward primer of each couple conjugated with a fluorescent dye (fluorescein) at its 5′ end. PCR products were then loaded on the ABI Prism 3730 DNA Analyzer for automated capillary gel electrophoresis and the results were plotted with the AbiPrism GeneMapper v3.5 software (Applied Biosystems). Results: On the 61 de novo adult BCR-ABL1-positive ALL pts, AID mRNA and protein were detected in 41 (67%). AID expression correlated with the BCR-ABL1 transcript levels and disappeared after treatment with tyrosine kinase inhibitors at the time of remission. Moreover, AID expression was also found in lymphoid blast crisis CML (60%), but not in myeloid lineage or in chronic phase CML. Different isoforms of AID were expressed. In 10/61 (16%) BCR-ABL1-positive ALL pts the full-length isoform (GeneBank accession number NM_020661) was identified, in 16/61 (26%) the co-expression of the wild-type isoform and of different AID splice variants was found and in 15/61 (25%) only the expression of splice variants was found. These can result from retention of intron 4 (Variant A), omission of exon 4 (Variant B) and 3 (Variant C), and from a deletion of 30 bp in the initial portion of exon 4 (Variant D). In the wild-type mRNA, codon 148 spans exons 3 and 4. In both variants A and B, mRNA splicing disrupts this codon and causes a frameshift, which results in a premature stop codon. If translated, the splice variants produce truncated proteins of 187 and 145 amino acids, respectively. However, the putative deaminase active site, encoded by exon 3, is preserved in both splice variants, but is lacking in the variant C. Since enforced expression of Pax5 induces endogenous AID gene expression, we analyzed the expression levels of Pax5 in all pts (ΔΔCt method, GAPDH as control gene). As expected, we found a very strong difference (p<0.0001) between chronic phase CML and BCR-ABL1-positive ALL, but total Pax5-transcripts did not differ significantly when BCR-ABL1-positive ALL/AID+ and BCR-ABL1-positive ALL/AID− were compared. To investigate whether AID introduces DNA-single strand breaks in BCR-ABL1-positive ALL, we performed a genome wide analysis by 250K NspI single nucleotide polymorphism (SNP) array (Affymetrix Inc., USA). We identified a region of high level amplification and homozygous deletion in all patients. Patients who expressed wild-type AID had a higher number of alterations compared to AID-negative patients (median copy number alteration of 14, range 5–27, versus 4, range 1–6, respectively, p<0.03). Recurring copy number abnormalities were identified in genes with an established role in leukemogenesis, such as IKZF1, CDKN2A, CDKN2B, PAX5, MELK, BTG1 and MDS1. AID consensus motifs (DGYW/WRCH) were mapped very close to the breakpoint cluster regions. Conclusions: Our findings show that BCR-ABL1-positive ALL cells aberrantly express different isoforms of AID that can act as a mutator outside the Ig gene loci in promoting genetic instability in leukemia cells.

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Central nervous system (CNS) leukemia after imatinib mesylate therapy for chronic myelogenous leukemia (CML)

Journal of Clinical Oncology ◽

10.1200/jco.2007.25.18_suppl.7042 ◽

2007 ◽

Vol 25 (18_suppl) ◽

pp. 7042-7042

Author(s):

M. M. Solh ◽

H. Kantarjian ◽

S. O'Brien ◽

F. Giles ◽

S. Faderl ◽

...

Keyword(s):

Overall Survival ◽

Kinase Inhibitors ◽

Blast Crisis ◽

Chronic Phase ◽

Cytogenetic Response ◽

Myelogenous Leukemia ◽

Leukemic Cells ◽

Blast Transformation ◽

Blast Phase ◽

Cns Disease

7042 Background: Imatinib is the standard first line treatment for CML. Imatinib penetrates the CSF poorly. We examined the incidence and outcome of CNS disease in pts with CML treated with imatinib at our institution. Methods: The clinical data for pts with early or late chronic phase and accelerated phase CML treated with imatinib between 1999 and 2006 were reviewed. Pts who were started on imatinib elsewhere and progressed to blast phase were also included. CNS disease was defined as a pathologically proven enhancing lesion (leptomeningeal or parenchymal) or presence of CSF leukemic cells. Results: Nine hundred and ten pts with chronic or accelerated phase CML were treated with imatinib. Fifty five developed blast crisis while on imatinib; another 28 pts had blast transformation while receiving imatinib elsewhere, making up a total of 83 pts. At diagnosis, their median age was 51 yrs, median Hgb, WBC and PLT counts were 10.6 g/dl, 59.7×109/L and 307×109/L, respectively. Median time from diagnosis to starting imatinib was 45.4 mts and the median duration of imatinib therapy was 17.9 mts. Fifteen pts had achieved a complete cytogenetic response and 47 had a complete hematologic response before progressing to blast phase. Their median overall survival from diagnosis was 73.2 mts. Thirty pts developed extramedullary disease; they had similar baseline characteristics as the rest with a median survival of 68.3 mts. Fifteen pts developed CNS disease (5 leptomenigeal, 5 CSF, 3 parenchymal, and 2 spinal cord); 14 had concomitant medullary blast crisis. They had a statistically significant younger age at diagnosis (41.9 vs 52.4 yrs), lower platelet counts (186 vs 334×109/L), and shorter overall survival (66.7 vs 73.2 mts) compared to the other pts with blast phase. Conclusions: CNS disease occurs infrequently in pts receiving imatinib for CML but should be suspected in pts with relevant symptoms. Pts developing CNS leukemia had a worse prognosis; this may be secondary to an inherently worse disease, poor CSF penetration of imatinib, and subsequent difficulty in eradicating CNS disease using available therapies. More potent tyrosine kinase inhibitors, such as nilotinib and dasatinib, and new agents with the ability to cross the blood-brain barrier should be evaluated in this setting. No significant financial relationships to disclose.

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Abnormal methylation of the calcitonin gene marks progression of chronic myelogenous leukemia

Blood ◽

10.1182/blood.v77.11.2431.2431 ◽

1991 ◽

Vol 77 (11) ◽

pp. 2431-2434 ◽

Cited By ~ 50

Author(s):

BD Nelkin ◽

D Przepiorka ◽

PJ Burke ◽

ED Thomas ◽

SB Baylin

Keyword(s):

Disease Progression ◽

Chronic Myelogenous Leukemia ◽

Blast Crisis ◽

Chronic Phase ◽

Methylation Pattern ◽

Myelogenous Leukemia ◽

Clinical Aspects ◽

Gene Methylation ◽

Peripheral Cell ◽

Blast Cells

Abstract The clinical aspects of disease progression in chronic myelogenous leukemia (CML) are well established, but the nature of the molecular events responsible is not known. We have previously reported a consistent pattern of novel sites of methylation in the 5′ region of the calcitonin (CT) gene and other chromosome 11p loci in acute myelogenous and and lymphoid leukemias. In the present study, CT gene methylation patterns were investigated in peripheral blood from 51 patients with CML. Abnormal patterns were found in only 2 of 31 patients in chronic phase, but in 5 of 8 patients in accelerated phase, and in 11 of 12 patients in blast crisis (P less than .005). For one patient studied in blast crisis, abnormal CT gene methylation was found in the peripheral blast cells but not in the granulocytes. In two of three patients studied with CML and having normal peripheral cell patterns, abnormal patterns were found in marrow blast cells. In one patient, only partial normalization of the CT gene methylation pattern was seen after chemotherapy induction of a second chronic phase and the patient relapsed 5 months later. Our findings indicate that abnormal methylation of the 5′ region of the CT gene is regularly a marker of disease progression in CML which may prove clinically useful. This abnormal methylation site is part of an imbalance in DNA methylation that may play a role in the progressive genetic instability which characterizes the advancing stages of CML.

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Loss of myeloid differentiation antigens precedes blastic transformation in chronic myelogenous leukemia

Blood ◽

10.1182/blood.v70.1.122.122 ◽

1987 ◽

Vol 70 (1) ◽

pp. 122-131 ◽

Cited By ~ 8

Author(s):

MB Todd ◽

JA Waldron ◽

TA Jennings ◽

LS Rome ◽

SD Markowitz ◽

...

Keyword(s):

Bone Marrow ◽

Bone Marrow Biopsy ◽

Bone Marrow Cells ◽

Blast Crisis ◽

Chronic Phase ◽

Myelogenous Leukemia ◽

Blast Transformation ◽

Myeloid Antigens ◽

Biopsy Specimens ◽

The Mean

Abstract In order to determine whether antigenic patterns alter with disease progression and are thereby suggestive of impending blast crisis in chronic myelogenous leukemia, 50 bone marrow biopsy specimens from 32 patients were examined retrospectively using indirect immunoperoxidase labeling with three monoclonal antibodies that detect myeloid antigens. Monoclonal antibodies PMN13F6, PMN7C3, and PMN8C7 detect human neutrophil antigens that first appear at the myeloblast, promyelocyte, and metamyelocyte stages of differentiation, respectively, and persist throughout later differentiation. Percentages of antigen-positive bone marrow cells during the chronic phase were compared with percentages of antigen-positive cells at blast transformation, and time from bone marrow biopsy until blast crisis was correlated with the percentage of bone marrow cells expressing these antigens. Bone marrow biopsy samples from patients in the chronic phase who continue to remain clinically stable 4 to 106 months after biopsy expressed PMN13F6 antigen on 82% +/- 9% (mean +/- SD) of cells, PMN7C3 antigen on 62% +/- 14% of cells, and PMN8C7 on 68% +/- 14% of cells. Bone marrow biopsy specimens obtained from patients 1 or more years prior to blast transformation expressed PMN13F6 antigen on 81% +/- 12%, PMN7C3 antigen on 71% +/- 16%, and PMN8C7 on 64% +/- 16% of cells. Bone marrow biopsy samples obtained between 2 months and 1 year prior to blast crisis expressed PMN13F6 antigen on 68% +/- 15%, PMN7C3 on 51% +/- 17%, and PMN8C7 antigen on 46% +/- 18% of cells. Bone marrow biopsy specimens taken at the time of blast transformation expressed PMN13F6 antigen on 20% +/- 25%, PMN7C3 antigen on 19% +/- 25%, and PMN8C7 antigen on 13% +/- 25% of cells. The difference between the mean of antigen-positive cells from bone marrow biopsy samples obtained at the time of blast crisis was significant compared with the mean of positive cells from biopsy specimens obtained at all other phases of the disease (P less than .001 for all three antibodies). There was a positive correlation between loss of myeloid antigens and disease progression as determined by simple regression of log time and correlation analysis (PMN13F6, r = .6533, P less than .005; PMN7C8, r = .6304, P less than .005; PMN8C7, r = .5215, P less than .05). There was a negative correlation between percentage of immature cells and time to blastic crisis (r = -.6206, P less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)

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Relationship of bcr breakpoint to chronic phase duration, survival, and blast crisis lineage in chronic myelogenous leukemia patients presenting in early chronic phase [see comments]

Blood ◽

10.1182/blood.v75.10.2035.bloodjournal75102035 ◽

1990 ◽

Vol 75 (10) ◽

pp. 2035-2041

Author(s):

SW Morris ◽

L Daniel ◽

CM Ahmed ◽

A Elias ◽

P Lebowitz

Keyword(s):

Chronic Myelogenous Leukemia ◽

Fusion Gene ◽

Blast Crisis ◽

Cell Lineage ◽

Chimeric Protein ◽

Chronic Phase ◽

Chromosome 9 ◽

Myelogenous Leukemia ◽

Phase Duration ◽

Total Survival

Strong evidence implicates fusion of control elements and 5′ sequences of the bcr gene of chromosome 22 with 3′ sequences of the c-abl gene of chromosome 9 in the pathogenesis of Ph-positive and certain cases of Ph- negative chronic myelogenous leukemia (CML). Since this fusion gene gives rise to a chimeric tyrosine protein kinase with transforming potential, and since the bcr exon contribution to this chimeric protein is variable, the question has arisen as to whether bcr breakpoint location and bcr exon contribution could influence the clinical course of CML. Prior studies have yielded conflicting results on this point. Here we have looked, in a manner approximating a prospective analysis, at the relation of bcr breakpoint localization to the duration of chronic phase, total survival, and blast crisis phenotype in 81 patients presenting in the chronic phase of CML. We have found no significant differences in chronic phase duration or total survival among patients with breakpoints in the three major subregions of a breakpoint cluster region within the bcr gene. These findings indicate that chronic phase duration and total survival cannot be predicted from bcr breakpoint for CML patients presenting in chronic phase and suggest that unknown oncogenic events determining the onset of blast crisis are the prime determinants of prognosis. Combined analysis of blast crisis cell lineage in our patients and patients presented in a previous study has revealed an overall ratio of myeloid:lymphoid (M:L) crisis of 3.4:1, but a striking predominance of myeloid crisis in patients with breakpoints in subregion 2 (M:L of 9:1), and a lower than expected M:L ratio (1.6:1) among patients with breakpoints in subregion 3 (P for subregion 2 versus 3 = .012; subregions 0,1,2 versus 3 = .012; subregions 0,1,3 versus 2 = .032). The molecular basis for this divergence from the anticipated M:L ratio in patients with breakpoints in bcr subregions 2 and 3 is unknown.

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Basophils (Bsp-1+) derive from the leukemic clone in human myeloid leukemias involving the chromosome breakpoint 9q34

Blood ◽

10.1182/blood.v73.3.777.bloodjournal733777 ◽

1989 ◽

Vol 73 (3) ◽

pp. 777-781

Author(s):

MP Bodger ◽

CM Morris ◽

MA Kennedy ◽

JA Bowen ◽

JM Hilton ◽

...

Keyword(s):

Toluidine Blue ◽

Myeloid Leukemia ◽

Blast Crisis ◽

Interleukin 2 ◽

Philadelphia Chromosome ◽

Chronic Phase ◽

Normal Karyotype ◽

Buffy Coat ◽

Chromosome 9 ◽

Leukemic Clone

The monoclonal antibody (MoAb) Bsp-1 was used to purify basophilic cells from leukemic blood of five patients with Philadelphia chromosome (Ph′) positive chronic myeloid leukemia (CML) and two patients with acute myeloid leukemia (AML) characterized by the chromosomal translocation t(6;9)(p23;q34). When cultured, Bsp-1 positive cells from all CML and AML patients showed the same clonal karyotype changes observed in diagnostic buffy coat preparations, indicating that the basophilic cells were of leukemic origin. In contrast, T lymphocytes from four of five CML patients cultured in the presence of interleukin- 2 (IL-2) showed a normal karyotype and were therefore not derived from the leukemic clone. Bsp-1 staining correlated with toluidine blue- positive basophils in chronic phase CML and with toluidine blue- negative blast cells expressing an immature myeloid phenotype in blast crisis CML and AML. Chromosome in situ hybridization showed that the ABL oncogene was translocated from chromosome 9 to chromosome 22 in the CML patients but remained on chromosome 9 in the AML patients. These results indicate that the breakpoint at 9q34 in CML is 5′ of ABL, whereas the breakpoint at 9q34 in AML is 3′ of ABL. Field inversion gel electrophoresis showed that the 9q34 breakpoint was not within 200 kb 3′ of ABL in one of the AML patients, nor was there any rearrangement of the PIM oncogene locus at 6p21.

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