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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The in vitro cytotoxic properties of acetaldoifosphamide, a new chemically stable bis-acetate analogue of aldoifosphamide that requires enzymatic activation by cellular carboxylate esterases, has been compared with that of 4-hydroperoxycyclophosphamide (4-HC). On a molar basis, acetaldoifosphamide was 8-10 times more potent than 4-HC against two different human leukemic myeloid cell lines, but only twice as potent as 4-HC against normal bone marrow granulocyte-macrophage colony-forming cells (GM-CFC). Acetaldoifosphamide retained its activity against leukemic cell lines that were highly resistant to the antileukemic drugs doxorubicin and m-AMSA. GM-CFC doubling times after exposure of bone marrow to high concentrations of acetaldoifosphamide in suspension cultures were 6-12 hours. Similar doubling times were obtained after incubation of marrow with 4-HC. Acetaldoifosphamide has a sparing effect on hematopoietic stem cells that is similar to that found for 4-HC; however, it is considerably more potent than 4-HC. Acetaldoifosphamide is different from 4-HC in its chemical stability and its unique requirement for carboxylate esterase activation. We conclude that acetaldoifosphamide may have advantages over 4-HC for in vitro purging of leukemic cells from human bone marrow.
Leukemia 1990 Jun
PMID:Suitability of a new stable acetal analogue of aldoifosphamide for purging leukemic cells from human bone marrow. 235 43

CI-937 and CI-942 belong to a new class of DNA complexers, the anthra[1,9-cd]pyrazol-6(2H)-ones (anthrapyrazoles), and are being further developed as antitumor drugs based on their curative properties against murine solid tumour models. The biochemical effects of these agents were studied in L1210 leukemia in relation to other clinically used intercalators. After a 1-hr exposure, CI-937 and CI-942 reduced the cloning efficiency of L1210 cells by 50% at 3.0 X 10(-8) and 1.5 X 10(-7) M respectively. Based on an ethidium displacement assay, these drugs bound strongly to DNA, reducing the fluorescence of an ethidium-DNA complex by 50% at concentrations of 23 and 33 nM for CI-937 and CI-942 respectively. This was comparable to mitoxantrone at 15 nM, but much more potent than Amsacrine which required over 1.3 microM. A distinct property of the anthrapyrazoles was a much more potent inhibitory effect on whole cell DNA synthesis than on RNA synthesis. After L1210 cells were exposed to drug for 2 hr the concentration needed to inhibit DNA synthesis by 50% was 0.33 and 0.57 microM for CI-937 and CI-942, respectively, whereas 2.0 and 11.3 microM were required to inhibit RNA synthesis by the same extent. This was in contrast to Adriamycin and mitoxantrone which inhibited both activities equally at similar concentrations. It was apparent that the inhibition of these processes was not due to substrate depletion since intracellular ribonucleoside and deoxyribonucleoside triphosphates either remained constant or were elevated after a 2-hr exposure to 1 or 10 microM drug. A similar discriminatory effect was observed on DNA and RNA polymerase in permeabilized cells, and the inhibition of nucleic acid synthesis in this system could be reversed by exogenously added DNA. Since the high incidence of cardiotoxicity associated with the administration of anthracyclines has been related to the formation of reactive oxygen species, the ability of the anthrapyrazoles to augment superoxide dismutase sensitive oxygen consumption was observed in a rat liver microsomal system. CI-937 and CI-942 induced 5- and 10-fold less oxygen consumption than Adriamycin, producing rates of 12.4, 24.2 and 138.9 nmoles/min/mg microsomal protein, respectively, at a drug concentration of 0.5 mM.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:In vitro DNA strand scission and inhibition of nucleic acid synthesis in L1210 leukemia cells by a new class of DNA complexers, the anthra[1,9-cd]pyrazol-6(2H)-ones (anthrapyrazoles). 241 61

Defining specific biochemical targets of active antineoplastic agents could aid in discovering better anticancer therapy and more thoroughly understanding the biochemical basis of malignancy. Through a series of cellular and biochemical studies, we and others have identified the nuclear enzyme topoisomerase II as the target of several active agents, including 4'-(9-acridinylamino) methanesulfon-m-anisidide (m-AMSA). The interference with topoisomerase II produced by m-AMSA can be quantified in whole cells exposed to m-AMSA by using the alkaline elution technique to measure DNA cleavage. Antimetabolites such as ara-C, hydroxyurea, and 5-azacytidine can augment m-AMSA-induced, topoisomerase II-mediated DNA cleavage and, concurrently, m-AMSA-induced cell killing. Studies in proliferating and quiescent human cells and an m-AMSA-sensitive/resistant human leukemia cell pair further support the hypothesis that a connection exists between topoisomerase II-mediated DNA cleavage and the mechanism by which m-AMSA kills cells. Pharmacologic or hormonal modification of specific biochemical processes critical to drug-induced cytotoxicity may enhance the therapeutic index of clinically useful agents.
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PMID:Intercalator-induced, topoisomerase II-mediated DNA cleavage and its modification by antineoplastic antimetabolites. 242 89

Amsacrine with high-dose cytarabine is effective therapy for Philadelphia chromosome (Ph1)-negative acute lymphoblastic leukemia (ALL). We examined the effectiveness of this regimen in 19 patients with Ph1-positive lymphoblastic leukemia. Four had an antecedent chronic phase of chronic myelogenous leukemia and 15 presented with ALL. There were no complete responders in either group. All 14 patients whose bone marrow could be assessed after completion of therapy showed persistent leukemia. We conclude that patients with Ph1-positive lymphoblastic leukemia have a disease that is resistant to treatment that is highly effective in patients with Ph1-negative ALL.
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PMID:Philadelphia chromosome (Ph1)-positive acute lymphoblastic leukemia (ALL) is resistant to effective therapy for Ph1-negative ALL. 250 96

Several fused tri- and tetracyclic quinolines (I and II) with [2-methoxy-4-[(methylsulfonyl)amino]phenyl]amino or [3-(N,N-dimethylamino)propyl]amino side chains were prepared, and their DNA intercalative properties, KB cytotoxicity, antitumor activity (P388 leukemia), and ability to induce topoisomerase II dependent DNA cleavage were investigated. Some compounds having both intercalative ability and KB cytotoxicity were found to be inactive in vivo. However, a positive correlation was seen between the ability to induce topoisomerase II dependent DNA cleavage and antitumor activity in vivo. The indeno- (13a), benzofuro- (21a), and benzothieno- (22a) quinoline derivatives exhibited potent antitumor activities in vitro and in vivo, comparable to those of m-AMSA. They also intercalate DNA and induce topoisomerase II dependent DNA cleavage. Extended screening of 13a showed it to be active against solid tumors such as M5076 sarcoma, B16 melanoma, and colon 38 carcinoma.
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PMID:Synthesis and antitumor activity of fused tetracyclic quinoline derivatives. 1. 254 58

HL-60/AMSA is a human leukemia cell line that is 100 times more resistant to the cytotoxic actions of the antineoplastic, topoisomerase II-reactive DNA intercalating acridine derivative amsacrine (m-AMSA) than is its parent HL-60 line. HL-60/AMSA cells are minimally resistant to etoposide, a topoisomerase II-reactive drug that does not intercalate. Previously we showed that HL-60 topoisomerase II activity in cells, nuclei, or nuclear extracts was sensitive to m-AMSA and etoposide, while HL-60/AMSA topoisomerase II was resistant to m-AMSA but sensitive to etoposide. Now we show that purified topoisomerase II from the two cell lines exhibits the same drug sensitivity or resistance as that in the nuclear extracts although the magnitude of the m-AMSA resistance of HL-60/AMSA topoisomerase II in vitro is not as great as the resistance of the intact HL-60/AMSA cells. In addition HL-60/AMSA cells are cross-resistant to topoisomerase II-reactive intercalators from the anthracycline and ellipticine families and the pattern of sensitivity or resistance to the cytotoxic actions of the various topoisomerase II-reactive drugs is paralleled by topoisomerase II-reactive drug-induced DNA cleavage and protein cross-link production in cells and the production of drug-induced, topoisomerase II-mediated DNA cleavage and protein cross-linking in isolated biochemical systems. In addition to its lowered sensitivity to intercalators, HL-60/AMSA differed from HL-60 in 1) the susceptibility of its topoisomerase II to stimulation of DNA topoisomerase II complex formation by ATP, 2) the catalytic activity of its topoisomerase II in an ionic environment chosen to reproduce the environment found within the living cell, and 3) the observed restriction enzyme pattern on a Southern blot probed with a cDNA for human topoisomerase II. These data indicate that an m-AMSA-resistant form of topoisomerase II contributes to the resistance of HL-60/AMSA to m-AMSA and to other topoisomerase II-reactive DNA intercalating agents. The drug resistance is associated with additional biochemical and molecular alterations that may be important determinants of cellular sensitivity or resistance to topoisomerase II-reactive drugs.
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PMID:Characterization of an amsacrine-resistant line of human leukemia cells. Evidence for a drug-resistant form of topoisomerase II. 255 Apr 42

Ledakrin [1-nitro-9-(3'-dimethylamino-N-propylamino)acridine], an antitumor drug of the 1-nitro-9-aminoacridine family, was able to induce DNA-protein crosslinks in intact L1210 leukemia cells, as demonstrated by the potassium-dodecyl sulfate precipitation technique. Ledakrin-induced DNA-protein crosslinks were not readily reversible nor were they accompanied by DNA double-strand breaks. Also, ledakrin produced virtually no crosslinks in isolated nuclei. Ledakrin-induced DNA-protein crosslinks seemed not to be mediated by topoisomerase II, unlike well-established effects of a chemically related antitumor drug, 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA). Four ledakrin analogs of divergent cytotoxic potencies also induced DNA-protein crosslinks but not DNA double-strand breaks in intact L1210 cells. A significant positive correlation existed between the ability of ledakrin and its 1-nitro analogs to induced DNA-protein crosslinks and the antiproliferative effects of these drugs. The results are consistent with the previously shown ability of 1-nitro-9-aminoacridines to covalently bind to macromolecules after metabolic activation in the cell. In addition to previously demonstrated DNA interstrand crosslinks and monofunctional adducts, DNA-protein crosslinks constitute another type of DNA lesion induced by 1-nitro-9-aminoacridines.
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PMID:Induction of DNA-protein crosslinks by antitumor 1-nitro-9-aminoacridines in L1210 leukemia cells. 255 39

Amsacrine, an acridine derivative used clinically in the treatment of acute leukaemia, has formed the basis for the development of further compounds with high activity against experimental solid tumours, one of which is currently in clinical trial. We have compared the ability of these drugs to cause point mutations in bacteria, 'petite' mutations in yeast and mutations in mammalian cells. Several of the compounds are frameshift mutagens in Salmonella typhimurium TA1537 while some cause 'petite' mutagenesis in Saccharomyces cerevisiae. All are highly clastogenic and have significant mutagenic activity at the 6-thioguanine locus in cultured V79 Chinese hamster fibroblasts following 1 h drug exposures. None are mutagenic at the ouabain locus of these cells. The relationship between different indicators of mutagenicity has been studied using an additional set of amsacrine analogues, some of which are mutagenic in S. typhimurium TA98. There is a highly significant relationship between mutation frequency (measured as resistance to 6-thioguanine) and either cytotoxicity (D37 values in a clonogenic assay) or clastogenicity (ability to induce micronuclei). However, there is no correlation with mutagenicity in microbial systems. The results suggest that the cytotoxicity, clastogenicity and mutagenic activity of the amsacrine analogues is mediated by similar mechanisms, probably involving the enzyme DNA topoisomerase II.
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PMID:Mutagenicity profiles of newer amsacrine analogues with activity against solid tumours: comparison of microbial and mammalian systems. 264 76

Several new cytostatic drugs have entered clinical Phase I-II studies for treatment of leukemia: most promising are pyrimidine analogues such as 5-Azacytosine arabinoside, 5-Aza-2-deoxycytidine, 5-Azacytidine, cyclocytidine, and 2'-2'-difluorodeoxycytidine. They act on different biochemical levels towards DNA-synthesis. Fludarabine is a purin analogue and seems very active in treating CLL. Tiazofurin is an antimetabolite counter-acting nicotinic acid with most promising activity in CML blast crisis. Other substances include deoxycoformycin, an adenosine analogue for treatment of T-cell neoplasias, 1, 25-dihydroxy vitamin D 3 as differentiation inducer, and homoharringtonine, an alkylating agent widely used for treating de novo AML in China. New anthracyclines are THP-adriamycin, fluoroadriamycin, and 4-demethoxydaunorubicin. Amsacrine (mAMSA) finally, is a synthetic aminoacridine with DNA-intercalating properties. The intact acridine ring appears essential for antitumor activity. The plasma clearance of both total amsacrine and unchanged parent species is biphasic. There is a considerable influence of hepatic and renal impairment on plasma clearance. Clinical toxicities include marked myelosuppression, gastrointestinal symptomes, phlebitis, mucocutaneous lesions, occasionally alopecia and neurotoxities. It is a very active drug, particularly in treating AML. Studies using mAMSA alone or in combination revealed comparable results to the anthracyclines. The E.O.R.T.C. Leukemia Cooperative Group has used successfully mAMSA in several trials: relapsed and refractory AML, intensive maintenance treatment during first remission in AML, and, still on-going, during intensive consolidation randomized against BMT in AML-patients under the age of 45 years, and randomized against standard consolidation between the age of 45 and 60 years.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:New drugs in the treatment of acute and chronic leukaemia: current role of mAMSA. 269 2

The identification of topoisomerase II as a target of antineoplastic drug therapy is traced from the original observations by Ross et al. (1,2) in murine leukemia cells through studies with m-AMSA-resistant human leukemia cells. Recently developed quantitative biochemical assays of topoisomerase II activity and the susceptibility of topoisomerase II to the effects of m-AMSA have allowed the principles identified in murine and human leukemia cell culture systems to be applied to clinical material; a prospective trial is testing the utility of such assays for individualizing antineoplastic drug therapy.
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PMID:Topoisomerase II as a target of antileukemic drugs. 281 36


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