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)

Several new cytostatic drugs have entered clinical phase I-II studies for the treatment of leukemia: the most promising are pyrimidine analogs such as 5-aza-cytidine, 5-aza-2'-deoxycytidine, 5-aza-cytosine arabinoside, and 2',2'-difluorodeoxycytidine. Fludarabine, a fluorinated purine analog, appears to be active in CLL and multiple myeloma. Deoxycoformycin, an adenosine analog, showed good activity in the treatment of hairy cell leukemia and T-cell neoplasias. 2-chloro-deoxyadenosine has recently been introduced into the treatment of CLL and hairy-cell leukemia refractory to deoxycoformicin. Tiazofurin, an antimetabolite which interferes with nicotine-adenine-dinucleotide (NAD) metabolism, has been applied in CML blast crisis. Other agents include 13-cis retinoic acid and 1, 25-dihydroxy vitamin D3 as differentiation inducers, and homoharringtonine, an alkylating agent which is widely used for ANLL treatment in China. Among new anthracyclines, aclarubicin, idarubicin, THP-adriamycin and fluoro-adriamycin should be mentioned. Mitoxantrone, a substituted anthraquinone, has successfully been applied in the treatment of relapsed and refractory ANLL. Amsacrine (m-AMSA), finally, is a synthetic aminoacridine which intercalates into DNA and inhibits DNA topoisomerase II. m-AMSA is not cross-resistant to anthracyclines and has been particularly active in ANLL treatment. Studies using m-AMSA alone or in combination revealed comparable results to anthracycline--containing regimens. Cardiotoxicity of the anthracycline congestive type has not been observed with m-AMSA. The EORTC Leukemia Cooperative Group has successfully used m-AMSA in several trials prepositioning this drug stepwise: from relapsed and refractory ANLL, into intensive maintenance treatment during first remission in ANLL, and, still on-going, into intensive consolidation.
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PMID:New drugs in the treatment of acute and chronic leukemia with some emphasis on m-AMSA. 206 23

The induced expression of multiple drug resistance (MDR)-associated genes as a direct response of tumor cells to antineoplastic drugs could be an important factor influencing the success of cancer chemotherapy. We investigated the effects of such compounds on mdr1/P-glycoprotein (P-gp) gene expression and drug sensitivities in the T-lymphoblastoid human cell line CCRF-CEM and MDR sublines. Thereby, we observed that actinomycin D or adriamycin administered at sublethal concentrations induced increases of mdr1 mRNA levels and resistance within 72 h. Furthermore, on leukemia cell samples collected before and after chemotherapy we checked by a complementary DNA polymerase chain reaction (cDNA-PCR) approach for similar alterations in the relative expression levels of the MDR-associated genes (a) mdr1/P-gp (b) mrp (MDR related protein), and (c) the topoisomerase II isoforms alpha and beta. We found a concomitant increase in mdr1 and mrp gene expression combined with a decreased expression of topoisomerase II alpha in the course of the second relapse of an acute lymphoblastic leukemia (ALL). This points to the emergence of at least three different MDR mechanisms in this type of leukemia unresponsive to chemotherapy. A chronic myeloid leukemia (CML) in blast crisis, however, showed combined increases in mdr1 (about 20-fold) and mrp (about four fold) gene expression after intense but unsuccessful chemotherapy over a 6-month period. Our results indicate the occurrence of induced resistance in vitro and in vivo and suggest a contribution of the newly identified ATP-binding cassette (ABC) transporter MRP in MDR.
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PMID:Drug-induced changes in the expression of MDR-associated genes: investigations on cultured cell lines and chemotherapeutically treated leukemias. 791 48

The apoptosis-associated DNA strand breaks were detected in situ, in individual leukemic cells in peripheral blood and bone marrow of over 110 patients with different types of leukemia (ALL, AML, CML in blastic crisis, APL), prior to and during routine chemotherapy. The DNA strand breaks were labeled with digoxigenin- or biotin-conjugated dUTP in the reaction catalyzed by exogenous terminal deoxynucleotidyl transferase, and the cells, counterstained for DNA, were analyzed by bivariate flow cytometry. The proportion of cells with DNA strand breaks prior to therapy, most likely reflecting spontaneous apoptosis, varied from 0.1 to 16%, but in the large majority of cases was below 3%. Administration of drugs of different classes, which included DNA topoisomerase I (Topotecan) and II (mitoxantrone, VP-16) inhibitors, antimetabolite (ara-C) or microtubule poison (Taxol), all triggered the appearance of cells with extensive DNA breakage, typical of apoptosis, to up to 80%. The peak of the response, measured as maximal percent of cells with DNA strand breaks, which varied between individual patients by as much as factor 10, was generally seen between 8 to 24 h after the initial administration of DNA topoisomerase inhibitors, and somewhat later (48-72 h) during the response to Taxol or ara-C. Thus, the data show that the response to treatment with a variety of drugs, in terms of induction of apoptosis, can be conveniently measured by the present method. The prognostic value of the apoptotic index, before, as well as during treatment, is being estimated for each type of leukemia, in the ongoing prospective studies.
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PMID:Apoptotic cell death during treatment of leukemias. 807 83

Chromosome band 11q23 is a site of recurrent translocations and interstitial deletions in human leukemias. Recent studies have shown that the 11q23 gene HRX is fused to heterologous genes from chromosomes 4 or 19 after t(4;11)(q21;q23) and t(11;19)(q23;p13) translocations to create fusion genes encoding proteins with structural features of chimeric transcription factors. In this report, we show structural alterations of HRX by conventional Southern blot analyses in 26 of 27 de novo leukemias with cytogenetically diverse 11q23 abnormalities. The sole case that lacked HRX rearrangements was a t(11;17)-acute myeloid leukemia with French-American-British M3-like morphology. We also analyzed 10 secondary leukemias that arose after therapy with topoisomerase II inhibitors and found HRX rearrangements in 7 of 7 with 11q23 translocations, and in 2 of 2 with unsuccessful karyotypes. In total, we observed HRX rearrangements in 35 leukemias involving at least nine distinct donor loci (1q32, 4q21, 6q27, 7p15, 9p21-24, 15q15, 16p13, and two 19p13 sites). All breakpoints localized to an 8-kb region that encompassed exons 5-11 of HRX, suggesting that fusion proteins containing similar portions of HRX may be consistently created in leukemias with 11q23 abnormalities. We conclude that alteration of HRX is a recurrent pathogenetic event in leukemias with 11q23 aberrations involving many potential partners in a variety of settings including acute myeloid leukemia, acute lymphoblastic leukemia, chronic myelogenous leukemia in blast crisis, and topoisomerase II inhibitor-induced secondary leukemias of both the myeloid and lymphoid lineages.
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PMID:HRX involvement in de novo and secondary leukemias with diverse chromosome 11q23 abnormalities. 821 10

A new flow cytometric method is described to detect DNA strand breaks associated with apoptosis, by labeling the 3'-OH termini in the breaks with biotinylated dUTP in a reaction employing exogenous terminal deoxynucleotidyl transferase. The method has been applied in studies on leukemic HL-60 and MOLT-4 cell lines to reveal whether it is specific to apoptotic cells, and whether it can be used in the clinic to detect DNA breakage in leukemic cells during chemotherapy. There was labeling of mononuclear cells in peripheral blood of all 11 patients studied during chemotherapy for acute lymphoblastic, acute myelogenous, or chronic myelogenous leukemia (ALL, AML, or CML) in blastic crisis, indicating induced DNA damage; the number of labeled cells increased from 1-8% before treatment up to 80% during the course of treatment. The DNA topoisomerase inhibitors mitoxantrone, VP-16 (etoposide), and m-AMSA (amsacrine) were more effective in inducing DNA breaks than was hydroxyurea or cytosine arabinoside (AraC). Cells with DNA breaks were identified in peripheral blood for up to 5 days following administration of Mitoxantrone and VP-16. In the case of DNA aneuploid leukemias, the DNA breaks were predominant in the aneuploid cell subpopulations, whereas presumably non-neoplastic diploid cells were unlabeled. In one case of ALL there were two distinct subpopulations of aneuploid cells: one responded to the treatment (by DNA breakage) and the other was non-responding. Thus, cells undergoing apoptosis can be detected by this method of labeling DNA strand breaks and the technique is applicable for analysis of response of leukemic cells to chemotherapy. With this method it may be possible to identify tumor cell sensitivity or resistance to particular drugs early in the course of treatment.
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PMID:Induction of DNA strand breaks associated with apoptosis during treatment of leukemias. 848 18

Gene expression was analyzed by cDNA-PCR at the mRNA level in bone marrow samples (>80% blasts) from ALL (28 primary, 22 first relapses, 10 recurrent relapses), from AML (14 primary, 23 relapses), In peripheral blood lymphocytes from CLL (five untreated, 10 treated), in one CML in blast crisis in the course of the disease (four samples), and in bone marrow samples from healthy donors (12 specimens). We found low mean MDR1 expression in primary ALL, first relapses of ALL, and primary AML. Significantly higher mean relative MDR1 expression levels were seen in recurrent relapses of ALL, and in the group of relapsed state AML. MDR1 expression measured intermediate in bone marrow samples from healthy donors. The CLL lymphocytes showed generally relatively high MDR1 expression levels. MRP gene expression measured very similar in primary ALL, first relapses of ALL, primary AML, and normal bone marrow. Significantly increased MRP mRNA levels were observed in the groups of recurrent ALL and relapsed state AML. CLL lymphocytes also showed high MRP expression levels. A combined increase of MDRI (about 20-fold) and MRP (about four-fold) was monitored in samples obtained from the CML in blast crisis after chemotherapy. While no significant differences of the mean topoisomerase IIbeta mRNA levels were found throughout, a significantly decreased topoisomerase IIalpha gene expression was measured in first and recurrent relapses of ALL. In CLL lymphocytes either the expression of the topoisomerase IIalpha gene was not detectable by cDNA-PCR, or it measured very low. Topoisomerase IIalpha gene expression was correlated to cyclin A gene expression in the samples of acute leukemias, Indicating the link of topoisomerase IIalpha expression to the proliferative activity of these leukemic blast cells. Our results point to a potentially multifactorial emergence of multidrug resistance in particular states and types of leukemias.
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PMID:MDR1, MRP, topoisomerase IIalpha/beta, and cyclin A gene expression in acute and chronic leukemias. 865 99

Drug resistance often results in failure of anticancer chemotherapy in leukemias. Several mechanisms of drug resistance are known with multidrug resistance (MDR) being the best characterized one. MDR can be due to enhanced expression of certain genes (MDR1, MRP or LRP), alterations in glutathione-S-transferase activity or GSH levels and to reduction of the amount or the activity of topoisomerase II. Here we review the current status of the clinical significance of the various mechanisms of MDR in leukemias and also discuss possibilities for the reversal of MDR. MDR1 gene expression has been seen in many leukemias, notably in acute myeloid leukemia (AML) and blast crisis of chronic myeloid leukemia. Both MDR1 RNA and P-glycoprotein expression of the leukemic cells have been shown to correlate with poor clinical outcome in AML. However, preliminary results indicate that the MRP gene as well as the LRP gene can be expressed in AML. Thus, drug resistance in leukemias appears to be multifactorial. P-glycoprotein-mediated MDR can be reversed by several drugs. These resistance modifiers are currently evaluated with regard to their clinical efficacy. Despite some encouraging results, reversal of drug resistance and subsequent improvement in clinical outcome remains to be shown.
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PMID:Multidrug resistance in leukemias and its reversal. 903 Oct 75

Therapy with DNA topoisomerase II inhibitors has been shown to result in an increased risk of acute myeloid leukemia (AML), often presenting balanced translocations to chromosome bands 11q23 and 21q22. Also other balanced aberrations, more rarely observed in therapy-related AML (t-AML), such as t(15;17) and inv(16) have been associated with these drugs. Recently we observed a case of chronic myeloid leukemia (CML) with t(9;22) after therapy of a germ cell tumor with etoposide, cisplatin and bleomycin. Based on this case and a review of chemotherapy-related leukemias with t(9;22) from the literature, we suggest a causal relationship between therapy with DNA topoisomerase II inhibitors and development of various types of leukemia carrying the Philadelphia chromosome.
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PMID:Chemotherapy-related - late occurring - Philadelphia chromosome in AML, ALL and CML. Similar events related to treatment with DNA topoisomerase II inhibitors? 930 14

Previous studies have shown that K562 chronic myelogenous leukemia cells are resistant to induction of apoptosis by a variety of agents, including the topoisomerase II (topo II) poison etoposide, when examined 4 to 24 hours after treatment with an initiating stimulus. In the present study, the responses of K562 cells and apoptosis-proficient HL-60 acute myelomonocytic leukemia cells to etoposide were compared, with particular emphasis on determining the long-term fate of the cells. When cells were treated with varying concentrations of etoposide for 1 hour and subsequently plated in soft agar, the two cell lines displayed similar sensitivities, with a 90% reduction in colony formation at 5 to 10 mu mol/L etoposide. After treatment with 17 mu mol/L etoposide for 1 hour, cleavage of the caspase substrate poly(ADP-ribose) polymerase (PARP), DNA fragmentation, and apoptotic morphological changes were evident in HL-60 cells in less than 6 hours. After the same treatment, K562 cells arrested in G2 phase of the cell cycle but otherwise appeared normal for 3 to 4 days before developing similar apoptotic changes. When the etoposide dose was increased to 68 mu mol/L, apoptotic changes were evident in HL-60 cells after 2 to 3 hours, whereas the same changes were observed in K562 cells after 24 to 48 hours. This delay in the development of apoptotic changes in K562 cells was accompanied by delayed release of cytochrome c to the cytosol and delayed appearance of peptidase activity that cleaved the fluorogenic substrates Asp-Glu-Val-Asp-aminotrifluoromethylcoumarin (DEVD-AFC) and Val-Glu-Ile-Asp-aminomethylcoumarin (VEID-AMC) as well as an altered spectrum of active caspases that were affinity labeled with N-(Nalpha-benzyloxycarbonylglutamyl-Nepsilon-biotin yllysyl) aspartic acid [(2,6-dimethylbenzoyl)oxy]methyl ketone [z-EK(bio)D-aomk]. On the other hand, the activation of caspase-3 under cell-free conditions occurred with indistinguishable kinetics in cytosol prepared from the two cell lines. Collectively, these results suggest that a delay in the signaling cascade upstream of cytochrome c release and caspase activation leads to a long latent period before the active phase of apoptosis is initiated in etoposide-treated K562 cells. Once the active phase of apoptosis is initiated, the spectrum and subcellular distribution of active caspase species differ between HL-60 and K562 cells, but a similar proportion of cells are ultimately killed in both cell lines.
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PMID:Comparison of caspase activation and subcellular localization in HL-60 and K562 cells undergoing etoposide-induced apoptosis. 937 39

The major established cause of acute myeloid leukemia (AML) in the young is cancer chemotherapy. There are two forms of treatment-related AML (t-AML). Each form has a de novo counterpart. Alkylating agents cause t-AML characterized by antecedent myelodysplasia, a mean latency period of 5-7 years and complete or partial deletion of chromosome 5 or 7. The risk is related to cumulative alkylating agent dose. Germline NF-1 and p53 gene mutations and the GSTT1 null genotype may increase the risk. Epipodophyllotoxins and other DNA topoisomerase II inhibitors cause leukemias with translocations of the MLL gene at chromosome band 11q23 or, less often, t(8;21), t(3;21), inv(16), t(8;16), t(15;17) or t(9;22). The mean latency period is about 2 years. While most cases are of French-American-British (FAB) M4 or FAB M5 morphology, other FAB AML subtypes, myelodysplastic syndrome (MDS), acute lymphoblastic leukemia (ALL) and chronic myelogenous leukemia (CML) occur. Between 2 and 12% of patients who receive epipodophyllotoxin have developed t-AML. There is no relationship with higher cumulative epipodophyllotoxin dose and genetic predisposition has not been identified, but weekly or twice-weekly schedules and preceding l-asparaginase administration may potentiate the risk. The translocation breakpoints in MLL are heterogeneously distributed within a breakpoint cluster region (bcr) and the MLL gene translocations involve one of many partner genes. DNA topoisomerase II cleavage assays demonstrate a correspondence between DNA topoisomerase II cleavage sites and the translocation breakpoints. DNA topoisomerase II catalyzes transient double-stranded DNA cleavage and rejoining. Epipodophyllotoxins form a complex with the DNA and DNA topoisomerase II, decrease DNA rejoining and cause chromosomal breakage. Furthermore, epipodophyllotoxin metabolism generates reactive oxygen species and hydroxyl radicals that could create abasic sites, potent position-specific enhancers of DNA topoisomerase II cleavage. One proposed mechanism for the translocations entails chromosomal breakage by DNA topoisomerase II and recombination of DNA free ends from different chromosomes through DNA repair. With few exceptions, treatment-related leukemias respond less well to either chemotherapy or bone marrow transplantation than their de novo counterparts, necessitating more innovative treatments, a better mechanistic understanding of the pathogenesis, and strategies for prevention.
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PMID:Secondary leukemias induced by topoisomerase-targeted drugs. 974 98


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