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PubMed1981

9;22;15 complex translocation in Ph1 chromosome positive CML revealed by Giemsa-11 procedure in apparent lymphoid cells of blastic crisis.

A Ph1 chromosome positive chronic myeloid leukemia patient whose chronic phase lasted 7.5 years experienced a blastic transformation originating in the spleen. The spleen was infiltrated with undifferentiated blast cells that on cytogenetic analysis had a hyperdiploid karyotype and were Ph1 chromosome positive. The blast cells were negative for PAS, peroxidase. Sudan black and esterase stains. They were non-T, non-B with TdT activity. Remission was achieved in response to prednisone, vincristine, and adriamycin. Ph1 positive cells were present with cells responding to PHA stimulation throughout the course of the disease. A Giemsa-11 staining procedure male possible the ascertainment of a No. 9 translocation chromosome in blastic crisis cells that had also been present in Ph1 chromosome positive cells early in the disease. The presence of this translocation initially in myeloid cells and subsequently in apparent lymphoid cell types suggests the origin of this patient's leukemia as a pluripotential stem cell.

Azure Stains↗

PubMed2006

Advances and potential treatment for Philadelphia chromosome-positive adult acute lymphoid leukaemia.

Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukaemia (ALL) is the most common subtype of ALL in adults. Conventional chemotherapy-based approaches that are effective in other precursor B cell ALL cases have a poor chances of cure in patients with a Ph+ diagnosis. Therefore, allogeneic stem cell transplantation performed during the first remission is the recommended therapy. Recently, the availability of imatinib mesylate and other tyrosine kinase inhibitors and small molecules that affect the BCR/ABL signalling pathways has introduced a new therapeutic opportunity, and could change the treatment paradigm and prognosis for these patients. In this article, the results from clinical trials using imatinib in relapsed/refractory patients and as front-line therapy are described. In addition, preliminary experiences with novel tyrosine kinase inhibitors in imatinib-resistant Ph+ ALL are discussed.

Adult↗

PubMed1990

New type of Bcr/Abl junction in Philadelphia chromosome-positive chronic myelogenous leukemia.

A new and rare type of Bcr/Abl junction between exon C3 of the 3' portion of the Bcr gene and Abl exon 2 has been identified in the leukemic cells of two Ph1-positive chronic myelogenous leukemia patients in chronic phase. This is the fourth type of Bcr/Abl junction so far identified in Ph1-positive hematologic malignancies and is a consequence of an unusual breakpoint position on chromosome 22 that falls approximately 20 kb downstream of the major breakpoint cluster region (bcr) of the Bcr gene. The new hybrid mRNA is 540 base pairs (bp) longer than that expressed by the K562 cell line and could codify for a Bcr/Abl protein carrying 180 additional aminoacids with respect to the larger P210 protein so far identified. The hematologic phenotype expressed by the two patients carrying this unusual type of Bcr/Abl rearrangement does not significantly differ from that commonly seen in chronic myelogenous leukemia.

Amino Acid Sequence↗

PubMed1991

[T lymphoid blast crisis of Philadelphia chromosome-positive chronic myeloid leukemia: analysis of 3 cases].

BACKGROUND: To investigate the frequency of the T lymphoid phenotype in the blast crisis of chronic myelocytic leukemia (CML) with positive Philadelphia chromosome (Ph) and to evaluate the major clinical and hematologic features of the patients with this phenotype. METHODS: The presence of the TdT enzyme was assessed and specific monoclonal antibodies to the different hemopoietic lines were used to evaluate blast cells in 38 patients with blast crisis during Ph-positive CML. RESULTS: T lymphoid phenotype was found in three of the 38 patients, corresponding in all cases to immature T cells. In one patient, the blast crisis was the presenting feature of CML and in two the localization of the blast crisis was lymphadenopathic. In the two patients who could be followed up a favorable response to chemotherapy regimens including vincristine and prednisone was observed. CONCLUSIONS: Although uncommon, T lymphoid blast crisis in CML should no longer be considered exceptional. This phenotypic finding suggests that, at least in some cases, CML originates in a pluripotential stem cell common to all hemopoietic cells, including T lymphocytes.

Adult↗

PubMed2003

[Successful treatment with imatinib mesylate for Philadelphia chromosome-positive refractory acute myeloid leukemia].

A 51-year-old man was diagnosed as having Philadelpha (Ph) chromosome-positive acute myeloid leukemia (AML) with major-BCR/ABL mRNA. He achieved complete remission after induction chemotherapy. Five months later, he was again positive for the Ph chromosome despite additional chemotherapy. He was therefore treated with imatinib mesylate, a specific inhibitor of BCR/ABL tyrosine kinase, at a dose of 600 mg/day. However, the treatment was interrupted because of thrombocytopenia, skin eruption and face edema. After the patient recovered from these side effects, imatinib was readministered at a dose of 400 mg/day and a complete cytogenetic response was achieved. Imatinib is expected to be an effective drug for Ph chromosome-positive AML.

Benzamides↗

PubMed1993

An actin-binding function contributes to transformation by the Bcr-Abl oncoprotein of Philadelphia chromosome-positive human leukemias.

In Philadelphia chromosome-positive human leukemias, which include chronic myelogenous leukemia and some acute lymphocytic leukemias, the c-abl proto-oncogene on chromosome 9 becomes fused to the bcr gene on chromosome 22, and Bcr-Abl fusion proteins are produced. The Bcr sequences activate the Abl tyrosine kinase which is required for the transforming function of Bcr-Abl. The Bcr sequences also enhance an F-actin-binding activity associated with c-Abl. Here, we show that binding of c-Abl and Bcr-Abl proteins to actin filaments in vivo and in vitro is mediated by an evolutionarily conserved domain at the C-terminal end of c-Abl. The c-Abl F-actin-binding domain contains a consensus motif found in several other actin-crosslinking proteins. Mutations in the consensus motif are shown to abolish binding to F-actin. Bcr-Abl proteins unable to associate with F-actin have a reduced ability to transform Rat-1 fibroblasts and to abrogate the requirement for interleukin-3 in the lymphoblastoid cell line Ba/F3. In transformed cells, Bcr-Abl induces a redistribution of F-actin into punctate, juxtanuclear aggregates. The binding to actin filaments has important implications for the pathogenic and physiological functions of the Bcr-Abl and c-Abl proteins.

Actin Cytoskeleton↗

PubMedDate not supplied

[Philadelphia chromosome-positive acute lymphoblastic leukemia in childhood: a special risk group?].

The Philadelphia chromosome is rarely observed in acute myelogenous and acute lymphoblastic leukemias. There are only a few case reports about pediatric patients, the prognosis of whom seems to be extremely poor. Reviewing the case of a girl aged 18 months with Philadelphia chromosome positive acute lymphoblastic leukemia, the differences between this entity and blast crisis of chronic myelogenous leukemia are described. This subgroup of Philadelphia chromosome positive acute lymphoblastic leukemia may represent a new risk group.

Chromosomes, Human, 21-22 and Y↗

PubMed1987

Multiple molecular abnormalities in Ph1 chromosome positive acute lymphoblastic leukaemia.

The Ph1 chromosome is present in 95% of patients with chronic myelogenous leukaemia (CML). The Ph1 chromosome also occurs in 5-25% of children and adults with acute lymphoblastic leukaemia (ALL). This observation raises questions as to whether these diseases are similar or identical. In patients with CML the c-abl and bcr genes are translocated and abnormally expressed. We studied molecular events related to bcr and c-abl in five patients with ALL to determine its relationship to CML. Four had the Ph1 chromosome; the fifth a probable Ph1 chromosome. c-abl and bcr abnormalities identical to CML were detected in four suggesting a common molecular basis. One patient with the Ph1 chromosome and c-abl translocation lacked these molecular changes but had abnormal c-abl gene transcription apparently unrelated to bcr. These data suggest that Ph1 chromosome positive ALL is heterogeneous; in some patients the molecular abnormality is identical to CML; in others c-abl is likewise involved but via a different mechanism.

Adolescent↗

PubMed1999

Combination of CD80 and granulocyte-macrophage colony-stimulating factor coexpression by a leukemia cell vaccine: preclinical studies in a murine model recapitulating Philadelphia chromosome-positive acute lymphoblastic leukemia.

Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) is a highly aggressive malignancy caused by the bcr-abl translocation oncogene. To explore alternative treatments for Ph+ ALL we tested gene-modified cell vaccines in the BALB/c-derived BM185 leukemia model. We compared the efficacy of BM185 cell vaccine expressing CD80 alone or in combination with IL-2 or GM-CSF. Mice injected with viable BM185 leukemia cells modified to express CD80 and GM-CSF (BM185/CD80+GM-CSF) showed the highest leukemia rejection rates. Cell vaccines consisting of irradiated BM185/CD80+GM-CSF cells administered subcutaneously stimulated a potent cytotoxic T lymphocyte (CTL) response against parental BM185. Histological examination of the vaccination site showed a large concentration of immune cells. Administration of the BM185/CD80+GM-CSF cell vaccine before intravenous challenge with parental cells caused strong inhibition of leukemia development. Vaccination after subcutaneous challenge with BM185 cells caused efficient elimination of leukemia promoting 40-60% long-term survival rates. The immunization efficacy of the BM185/CD80+ GM-CSF cell vaccine was directly correlated with the percentage of cells expressing the transgenes. In all, this preclinical study shows that leukemia cell vaccines coexpressing CD80 and GM-CSF can potentially be explored for immunotherapy in Ph+ ALL patients.

Animals↗

PubMed1992

Antibody recognition of the tumor-specific b3-a2 junction of bcr-abl chimeric proteins in Philadelphia-chromosome-positive leukemias.

The reciprocal translocation between chromosome 9 and chromosome 22, as observed in chronic myeloid leukemia (CML) as well as in acute lymphoblastic leukemia (ALL), results in a 22q- chromosome, the so-called Philadelphia chromosome. The translocation event creates on the Philadelphia chromosome a fusion between two genes: bcr and abl. Depending on the localization of the breakpoint in the bcr gene different chimeric bcr-abl genes are generated, each encoding their own tumor-specific protein: e1-a2P190bcr-abl, b2-a2p210bcr-abl, or b3-a2P210bcr-abl. Especially in ALL, the presence of such a tumor-specific protein is highly associated with a poor prognosis. Detection of these proteins therefore has a strong clinical significance. In this study a polyclonal antiserum, termed BP-2, was raised against a synthetic peptide, corresponding to the tumor-specific 'fusion-point' epitope of the b3-a2P210bcr-abl protein. The specificity of BP-2 for the bcr-abl joining region in b3-a2P210bcr-abl is demonstrated by means of peptide inhibition studies in combination with immunoprecipitation. In addition we show the reactivity of BP-2 with bcr-abl proteins in leukemic cells of a Philadelphia-chromosome-positive ALL patient.

Amino Acid Sequence↗

PubMed2000

alpha-thalassemia resulting from a negative chromosomal position effect.

To date, all of the chromosomal deletions that cause alpha-thalassemia remove the structural alpha genes and/or their regulatory element (HS -40). A unique deletion occurs in a single family that juxtaposes a region that normally lies approximately 18-kilobase downstream of the human alpha cluster, next to a structurally normal alpha-globin gene, and silences its expression. During development, the CpG island associated with the alpha-globin promoter in the rearranged chromosome becomes densely methylated and insensitive to endonucleases, demonstrating that the normal chromatin structure around the alpha-globin gene is perturbed by this mutation and that the gene is inactivated by a negative chromosomal position effect. These findings highlight the importance of the chromosomal environment in regulating globin gene expression.

Chromosome Mapping↗

PubMed1983

Glucocorticoids and chromosomal position modulate murine mammary tumor virus transcription by affecting efficiency of promoter utilization.

The rate of transcription of murine mammary tumor virus (MTV) sequences in MTV-infected rat hepatoma tissue culture cells is strongly affected by both glucocorticoid hormones and the chromosomal position of provirus integration. We have characterized MTV RNAs produced in J2.17 and M1.54, independent isolates containing, respectively, 1 and 10 proviruses integrated at distinct chromosomal loci. M1.54, but not J2.17, synthesized MTV RNA in the absence of glucocorticoids; the rate of hormone-stimulated viral gene transcription in M1.54 was 50- to 100-fold higher than in J2.17. In each case in which MTV genes were expressed (J2.17 induced, M1.54 basal and induced), the viral RNAs produced were indistinguishable. RNA blotting revealed accumulation of two transcripts, 7.8 and 3.8 kilobases; the latter was likely produced from the former by RNA splicing. Sites used for transcription initiation, polyadenylation, and splicing have been identified from the sizes of end-labeled hybridization probes protected from digestion with mung bean nuclease; the unique initiation and polyadenylation sites were both encoded within the MTV long-terminal-repeat sequence. The efficiencies of splicing and of utilization of the polyadenylation signal did not appear to vary as functions of chromosomal position or hormonal stimulation. Differences in rates of viral gene transcription were reflected in the differential accumulation of the 5'-terminal 136 nucleotides of MTV RNA. Thus, glucocorticoids and chromosomal position appeared to affect solely the efficiency of utilization of the MTV promoter, leaving unchanged the sites of initiation, splicing, and polyadenylation, as well as the efficiencies of the latter two processes.

Animals↗

PubMed1983

Long-term marrow culture reveals chromosomally normal hematopoietic progenitor cells in patients with Philadelphia chromosome-positive chronic myelogenous leukemia.

We found that when marrow cells from four patients with newly diagnosed Philadelphia chromosome-positive chronic myelogenous leukemia were maintained in culture for two to four weeks, a previously undetectable population of chromosomally normal hematopoietic cells (including erythroid, granulopoietic, and pluripotent progenitors) became readily demonstrable in three cases. Time-course studies showed that in such cultures the dominant Philadelphia chromosome-positive population rapidly disappeared, in contrast to coexisting chromosomally normal progenitors, which remained detectable for periods of two to three months. Long-term marrow cultures thus offer a new approach to the assessment of a suppressed but functionally intact population of chromosomally normal hematopoietic stem cells in patients with chronic myelogenous leukemia.

Adult↗

PubMed1999

Evolutionary rate of a gene affected by chromosomal position.

Genes evolve at different rates depending on the strength of selective pressure to maintain their function. Chromosomal position can also have an influence [1] [2]. The pseudoautosomal region (PAR) of mammalian sex chromosomes is a small region of sequence identity that is the site of an obligatory pairing and recombination event between the X and Y chromosomes during male meiosis [3] [4] [5] [6]. During female meiosis, X chromosomes can pair and recombine along their entire length. Recombination in the PAR is therefore approximately 10 times greater in male meiosis compared with female meiosis [4] [5] [6]. The gene Fxy (also known as MID1 [7]) spans the pseudoautosomal boundary (PAB) in the laboratory mouse (Mus musculus domesticus, C57BL/6) such that the 5' three exons of the gene are located on the X chromosome but the seven exons encoding the carboxy-terminal two-thirds of the protein are located within the PAR and are therefore present on both the X and Y chromosomes [8]. In humans [7] [9], the rat, and the wild mouse species Mus spretus, the gene is entirely X-unique. Here, we report that the rate of sequence divergence of the 3' end of the Fxy gene is much higher (estimated at 170-fold higher for synonymous sites) when pseudoautosomal (present on both the X and Y chromosomes) than when X-unique. Thus, chromosomal position can directly affect the rate of evolution of a gene. This finding also provides support for the suggestion that regions of the genome with a high recombination frequency, such as the PAR, may have an intrinsically elevated rate of sequence divergence.

Animals↗

PubMed2005

Philadelphia-chromosome positive thrombocythemia in a child.

Philadelphia-chromosome positive thrombocythemia without features of chronic myeloid leukemia in peripheral blood has been described in adults. It is rare in children. We present a case of Philadelphia positive thrombocythemia in a child who was managed with a combination of imatinib and hydroxyurea. Although a reduction in the BCR-ABL transcript was documented, the thrombocytosis was refractory to imatinib alone and required the addition of hydroxyurea.

Benzamides↗

PubMed1996

Prognostic significance of additional chromosome abnormalities in adult patients with Philadelphia chromosome positive acute lymphoblastic leukaemia.

The clinical and biological significance of additional chromosome aberrations was investigated in a large series of 66 adult patients with Philadelphia (Ph) chromosome positive acute lymphoblastic leukaemia (ALL). Additional chromosome changes were observed in 71% of the cases. 9p abnormalities were identified in 26%, and monosomy 7 as well as hyperdiploid karyotypes 50 were both found in 17% of cases. 9p anomalies were characterized by a low complete remission (CR) rate (58%) and an extremely short median remission duration (MRD: 100 d). In patients with monosomy 7, the poor treatment outcome was confirmed (CR rate 55%: MRD 113 d). In contrast, all patients with hyperdiploid karyotypes 50 achieved CR, and the overall survival was superior to all other Ph-positive ALL patients except those without additional chromosome aberrations. Exclusive rearrangement of the minor breakpoint cluster region of the BCR gene and lack of coexpression of myeloid-associated antigens in cases with 9p anomalies as well as a high frequency of rearrangements of the major breakpoint cluster region of the BCR gene in patients with monosomy 7 (89%) further substantiated that additional chromosome aberrations may characterize distinct subgroups of Ph-positive ALL. Moreover, the necessity of the complementing use of chromosome banding analyses, polymerase chain reaction (PCR) assays, and fluorescence in situ hybridizations in the accurate identification of Ph-positive patients has become evident due to variant Ph translocations in 3%, and negative PCR assays in 4% of the cases.

Adolescent↗

PubMed2002

Alpha-interferon in combination with cytarabine in children with Philadelphia chromosome-positive chronic myeloid leukemia.

BACKGROUND: Philadelphia chromosome-positive chronic myelogenous leukemia (CML) is a rare disease in children, and the optimal therapy is not clearly defined in these patients when a human leukocyte antigen-identical donor is not available. The present work focuses on the therapeutic efficacy and the toxicity of interferon (IFN) alpha 2b in combination with cytosine arabinosine (Ara-C) in patients younger than age 18 years enrolled in the randomized trial CML 91, which compared the efficacy of IFN and cytosine arabinoside (Ara-C) with IFN alone in 810 patients with CML in the chronic phase. PATIENTS AND METHODS: Twelve patients younger than age 18 years were enrolled in the randomized trial CML 91. Hydroxyurea and IFN (5 million units/m2, once a day) were given as initial treatment in all patients. After randomization, six patients received IFN (5 million units/m2, once per day) and Ara-C (20 mg/m2 for 10 days each month) (IFN plus Ara-C group), and six patients received IFN alone (5 million units/m2 once per day) (IFN group). RESULTS: Six months after the beginning of the treatment, a complete hematologic response was obtained in all the patients in the IFN plus Ara-C group and in four patients in the IFN group. A major cytogenetic response was observed in three patients in the IFN plus Ara-C group and in two patients in the IFN group. Five patients from the IFN group who crossed over to receive Ara-C did not experience additional hematologic toxicity. Three patients in the IFN plus Ara-C group and two from the IFN group are alive, in major cytogenetic response, with a follow-up of 18 to 48 months. CONCLUSION: The combination of IFN and Ara-C induces complete hematologic and major cytogenetic responses and is well tolerated in patients younger than age 18 years with CML. This combination may offer an alternative to bone marrow transplantation in children in the chronic phase of CML without a histocompatible donor.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1988

Molecular analysis of clonality and bcr rearrangements in Philadelphia chromosome-positive acute lymphoblastic leukemia.

Philadelphia chromosome (Ph1)-positive chronic myelogenous leukemia (CML) patients consistently show a rearrangement in a 5.8-kilobase length of chromosome 22, referred to as the breakpoint cluster region (bcr). In Ph1-positive acute lymphoblastic leukemia (ALL), the breakpoint in chromosome 22 is more heterogeneous and, in some instances, does not occur within this region. In such cases the cell of origin of the neoplastic clone and the relationship of the disease to CML has remained obscure. We have analyzed the bcr rearrangement in the malignant cells from three patients who presented with Ph1-positive ALL and who in cytogenetic studies had shown evidence of variable involvement of myeloid cells in the Ph1-positive clone. Rearrangements in bcr typical of most cases of CML were detected in purified granulocyte preparations from two of the ALL patients (nos. 1 and 2) and in the blasts from patient 3 at the time of her terminal relapse. In the same analysis the simultaneously obtained granulocytes from patient 3, however, did not show any evidence of bcr rearrangement. Patient 3 was also heterozygous for the BamHI polymorphism in the X-linked hypoxanthine phosphoribosyltransferase (HPRT) gene, thus permitting a different method of clonal analysis based on methylation differences in active and inactive alleles. When DNA from her granulocytes that had shown no bcr rearrangement was hybridized to an HPRT probe, a pattern typical of a polyclonal population was seen. A similar pattern was exhibited by her marrow fibroblasts. In marked contrast, her simultaneously isolated blasts showed an unambiguous monoclonal pattern. These findings demonstrate the origin of the disease in the first two patients in a cell with myelopoietic as well as lymphopoietic potential and confirm the restricted lymphoid cell origin of the neoplastic clone in the third Ph1-positive ALL patient. Furthermore, they indicate that different target cells for transformation within the hematopoietic system may be affected by very similar bcr rearrangements.

Blast Crisis↗