Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Leukemic cells from patients with Philadelphia chromosome (Ph1)-positive chronic myelogenous leukemia (CML) contain a 210 kDa protein (P210bcr-abl) with a protein tyrosine kinase activity that is a product of fused bcr and abl genes. We have prepared two monoclonal anti-peptide antibodies, one from each gene product, and have affinity purified each. Incubation of anti-abl (c-abl 51-64) immunoprecipitates of K562 cells with [gamma-32P]ATP in protein kinase assays resulted in the labeling of P210bcr-abl and a 53 kDa (ph-P53) protein. Increasing concentrations of antibody detected similar ratios of P210bcr-abl: ph-P53, suggesting the presence of a complex between the proteins. Several different anti-abl and anti-bcr antibodies detected the ph-P53/P210 complex. Sodium dodecyl sulfate (SDS) treatment without 2-mercaptoethanol eluted P210bcr-abl and ph-P53 from the monoclonal antibody in the form of complexes which migrated on 6% SDS-polyacrylamide gels and had apparent molecular weights of 275,000 and more than 500,000. Both complexes yielded ph-P53 and P210bcr-abl upon treatment with SDS-mercaptoethanol. Studies involving glycerol gradient centrifugation also detected complexes of P210bcr-abl and ph-P53. Our results indicate that ph-P53 is not a degraded product of P210bcr-abl, does not share antigenic determinants with P210bcr-abl since it is not recognized by anti-abl and bcr antibodies in immunoblots, is not the phosphorylated heavy chain of immunoglobulin G, and is different from p53 (the nonviral T protein) complexed to the large T antigen of simian virus 40. Previous studies (Maxwell et al., 1987) have shown that ph-P53 has a different peptide map than P210bcr-abl. Therefore, we conclude that ph-P53 is a distinct cellular protein complexed to P210bcr-abl in K562 cells.
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PMID:A novel 53 kDa protein complexed with P210bcr-abl in human chronic myelogenous leukemia cells. 313 27

The p53 is a nuclear protein that is associated with normal cellular proliferation and can cooperate with Ha-ras in causing cellular transformation in vitro. Lineage association is known to exist between p53 expression and normal lymphopoiesis, but not myelopoiesis. We studied the expression of p53 using chronic myelogenous leukemia (CML) cell lines, somatic hybrids of these cells, and leukemic cells from CML patients. Lymphoid CML lines expressed both p53 mRNA and protein. We also analyzed p53 synthesis by two B-lymphoid lines from the same CML patient; cells of one line were derived from the neoplastic clone, cells of the other were derived from the normal clone. Both synthesized equal amounts of a phosphorylated p53 protein. None of the myeloid CML lines expressed detectable p53 protein and two of four expressed negligible p53 mRNA. Two other myeloid CML lines and myeloid cells from three of four patients expressed p53 mRNA. These findings suggest that expression of the gene is not regulated normally in CML. Several approaches were pursued to explore the differential expression of p53. Southern blot analyses showed no gross alterations in the p53 gene from cells of either the expressing or the nonexpressing lines. No difference in the pattern of demethylated CpG sites was noted in the region of the p53 gene in cells from K562 (myeloid p53 nonexpressor) and in BV173 (lymphoid p53 expressor). The sites of demethylation clustered in and around the p53 promoter in both cell lines. Somatic hybrids formed between a p53 mRNA nonexpressor myeloid line (K562) and the parental p53 expressor lymphoid lines (Daudi, PUT) produced p53 mRNA and protein, suggesting that p53 is a dominantly expressed protein and that lack of expression in myeloid cells is not mediated by a trans-acting negative regulatory protein. DNA transfection experiments performed using the indicator gene chloramphenicol acetyltransferase attached to promoter sequences of p53 showed that these constructs were equally activated in BV173 (p53 expressor) and K562 (p53 mRNA nonexpressor). The mechanism of p53 regulation in CML remains unclear.
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PMID:p53 in chronic myelogenous leukemia. Study of mechanisms of differential expression. 328 Jul 26

This review attempts to provide current information on the role played by the p53 gene in normal and leukemic hematopoiesis with particular emphasis on chronic myeloid leukemia. On the basis of the currently available data we can argue that p53 acts as a negative regulator of proliferation of myeloid mature cells and CD34+ progenitors, and its action is mediated through changes in cell cycle kinetics, mainly before the S phase. The p53-dependent pathway is also regulated by several proteins, including p16, p21, p27 (cyclin-dependent kinase [CDK] inhibitors), and a few oncogenes (bcl-2, bax, MDM-2). Although there is some information about the changes in the p53 gene seen in various types of leukemia, the functions and biological importance of these changes in the pathogenesis of leukemia are still largely elusive. During the past several years, accumulated evidence suggests that changes in the p53 gene are commonly associated with blast crisis of chronic myeloid leukemia (CML) but rarely with chronic phase, and they are represented by rearrangements, deletions and point mutations. As for most of the tumors, the majority of point mutations occur between exons 4 and 8 (hot regions). In patients with CML in blastic crisis the most frequent mechanism of p53 inactivation is complete deletion of one allele in association with a point mutation in the remaining allele.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of p53 in leukemogenesis of chronic myeloid leukemia. 754 4

A critical determinant of the efficacy of antineoplastic therapy is the response of malignant cells to DNA damage induced by anticancer agents. The p53 tumor-suppressor gene is a critical component of two distinct cellular responses to DNA damage, the induction of a reversible arrest at the G1/S cell cycle checkpoint, and the activation of apoptosis, a genetic program of autonomous cell death. Expression of the BCR-ABL chimeric gene produced by a balanced translocation in chronic myeloid leukemia, confers resistance to multiple genotoxic anticancer agents. BCR-ABL expression inhibits the apoptotic response to DNA damage without altering either the p53-dependent WAF1/CIP1-mediated G1 arrest or DNA repair. BCR-ABL-mediated inhibition of DNA damage-induced apoptosis is associated with a prolongation of cell cycle arrest at the G2/M restriction point; the delay of G2/M transition may allow time to repair and complete DNA replication and chromosomal segregation, thereby preventing a mitotic catastrophe. The inherent resistance of human cancers to genotoxic agents may result not only by the loss or inactivation of the wild-type p53 gene, but also by genetic alterations such as BCR-ABL that can delay G2/M transition after DNA damage.
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PMID:BCR-ABL-mediated inhibition of apoptosis with delay of G2/M transition after DNA damage: a mechanism of resistance to multiple anticancer agents. 762 Jan 67

The frequent involvement of chromosome 17p abnormalities in the progression of chronic myeloid leukaemia (CML) led us to investigate the involvement of the p53 tumour suppressor gene located on chromosome 17p. We analysed 31 samples from four patients sequentially, and 16 patients in blast crisis only, using single stranded conformational polymorphism (SSCP) analysis of exons 5-8, followed by cloning and sequencing. The sequential samples ranged from diagnosis through to late disease. We found that 15% of our blast crisis samples had p53 abnormalities. In our sequential studies we found two of the four patients analysed in more detail had p53 mutations in the late chronic phase of disease (11 and 5 months prior to blast crisis becoming apparent). These chronic phase mutations differed from the p53 abnormalities found in the blast crisis samples from these patients. One patient also had the same chronic phase mutation at post bone marrow transplant relapse. Our results suggest that, in some cases, sequential investigations through CML disease progression of p53 mutations and other oncogenes/proto-oncogenes may provide early indications of the routes of disease progression to blast crisis.
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PMID:Changing p53 mutations with the evolution of chronic myeloid leukaemia from the chronic phase to blast crisis. 765 97

A patient with Philadelphia-positive chronic myelogenous leukemia (CML) evolved in extramedullary blast crisis, was studied for the presence of alterations of the P53 tumor suppressor gene in the different stages of disease progression. No P53 gene aberrations were detected during the chronic and accelerated phases. Two identical missense point mutations, involving codons 249 and 281 and leading to the amino acid substitutions Arg-Ser and Thy-Asp, were identified in cells of an extramedullary mass and then in peripheral blood blast crisis cells. The data indicate that the medullary and extramedullary blast cells belong to the same cellular clone. They also strongly suggest that in this case, the alteration of P53 gene is strictly related to the progression of the disease, although this mechanism is certainly neither the only nor the most frequent molecular event leading to the acute phase.
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PMID:Double P53 point mutation in extramedullary blast crisis of chronic myelogenous leukemia. 769 24

Loss of the p53 gene alleles was investigated in 26 patients with Ph+, BCR/ABL+ chronic myeloid leukemia (CML) by means of the polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis using the restriction enzyme AccII. In all cases, peripheral blood and/or bone marrow samples were obtained at different times during the chronic phase of the disease and at blast crisis, and in some of them also at the accelerated phase. Of the 12 cases considered informative, 11 evolved into myeloid type blast crisis and one into a lymphoid blast crisis, whereas only two showed an i(17q) chromosome at cytogenetic study. In four of the 12 informative cases, a loss of one p53 gene allele was observed, in all cases coincident with the development of the accelerated phase or blast crisis. One patient with a deleted p53 gene allele, in whom it was possible to analyze the gene structure in the three CML evolutive phases (chronic and accelerated phases and blast crisis), showed loss of the p53 gene allele in both the accelerated and the blastic phase, but not during the chronic phase. On the other hand, one of the two cases with an i(17q) chromosome exhibited one allelic deletion of the p53 gene. Thus, the relatively frequent monoallelic deletion of the p53 gene coincident with the appearance of the blast crisis registered in the present study would support a possible role of the p53 gene alterations in the evolution of CML to its final stages.
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PMID:P53 tumor suppressor gene in chronic myelogenous leukemia: a sequential study. 771 41

DNA from 36 patients with chronic myelogenous leukemia (CML) at various clinical stages and 6 cases of acute leukemia was investigated for alterations of the p53 gene by Southern blot analysis. Rearrangements of the p53 gene were seen in 3 of 12 (25.00%) cases of blast crisis and accelerated phase (AP) of CML and in only one of 18 chronic phrase (CP), just as has been reported previously. Meanwhile, by restriction fragment length polymorphism (RFLP) analysis the Bgl II site polymorphism in the p53 gene was also found. The frequency in Chinese people detected here was 0.392, which was strikingly higher than that in some other countries (P < 0.001). These results suggested that the alterations of the p53 gene, for example, p53 rearrangements, were probably responsible for the progression of BC in some CML patients, and that the frequency of Bgl II polymorphism in the p53 gene might be related to the population distribution.
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PMID:Preliminary research on the p53 gene rearrangements in the evolution of chronic myelogenous leukemia to blast crisis. 776 Apr 28

Mutations of the p53 tumour suppressor gene occur in 20% of chronic myeloid leukaemia (CML) patients in blastic crisis, but it is still uncertain whether this inactivation plays a role in the pathogenesis of blastic transformation or in maintaining the leukaemic proliferation in CML, as it does in several solid tumours. We have previously shown that more than 50% of both normal and CML CD34+ cells express the p53 protein. However, haemopoietic cells at different phases of the cell cycle express p53 with different conformations, suggesting that the function of p53 may be closely regulated during the cell cycle. In order to elucidate the mechanism by which p53 suppresses cell proliferation, we evaluated the effects of inhibiting p53 expression on cell cycle and cell kinetics of chronic phase CML (n = 12) and normal (n = 7) bone marrow light-density cells and purified CD34+ progenitors by using an 18-mer modified antisense oligonucleotide which targets the region covering the six base pairs immediately before the first codon and the first four coding codons of p53. We found that the number of cells positive for the cell cycle-specific nuclear antigen Ki67 and for the BrdU monoclonal antibody (McAb) was significantly increased after p53 antisense olignucleotide treatment. At the same time, p53 protein expression was completely abrogated in both light-density and CD34+ cells. In addition, DNA analysis by flow cytometry demonstrated that the number of cells in quiescent phases of the cell cycle (G0-G1) was significantly decreased after exposure of light-density cells to p53 antisense oligomers, whereas the number of cells in S or G2-M phases was increased. Furthermore, the longer the incubation time the higher the increase in cell proliferation. Treatment of CML, cells with p53 antisense oligomers also resulted in significantly increased numbers of CFU-GM colonies. Our data suggest that p53 is a negative regulator of cell proliferation and its action is mediated through changes in cell cycle kinetics, mainly before the S phase. We can further speculate that the loss of p53 function, at the time of blastic crisis of CML, may play a role, in combination with other genetic changes (p210 BCR/ABL, Rb gene abnormality, others to be defined), in inducing disturbances in cell proliferation, differentiation, and apoptosis.
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PMID:Modulation of cell kinetics and cell cycle status by treating CD34+ chronic myeloid leukaemia cells with p53 antisense phosphorothioate oligonucleotides. 778

A new Ph1-positive leukemic cell line (MC3) expressing the P210bcr/abl oncoprotein was established from a patient with CML in blast crisis. The MC3 cells showed the trilineage phenotype of myeloid, lymphoid (CD19) and megakaryocytoid lineages, and had a proliferative response to rhIL-1 and rhIL-3 in the serum-free culture. These results and the expression of CD34 indicated that the MC3 cells have characteristics of hematopoietic progenitor cells. Recently, it has been documented that alterations of the p53 gene in leukemic cells are frequently detected during the blast crisis of CML. The MC3 cells contained the altered p53 gene. In addition, the original leukemic cells showed the point-mutational activation of the N-ras gene and an additional chromosomal abnormality inv(3q), but the MC3 cells contained no such abnormalities, indicating that not all of the original leukemic cells had these abnormalities. Thus, the MC3 cell line may provide several insights into investigations of the blast crisis in CML as well as hematopoietic progenitor cells.
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PMID:Establishment and characterization of a new Ph1-positive chronic myeloid leukemia cell line MC3 with trilineage phenotype and an altered p53 gene. 778 56


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