Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Idarubicin (IDA) is an anthracycline used during treatment of acute myelogenous leukaemia (AML) and is clinically important because of its potency and lipophilicity (compared to the related compounds daunorubicin and doxorubicin). These drugs target DNA topoisomerase II (topo II), a nuclear enzyme that regulates DNA topology. Topo II poisoning leads to the trapping of an intermediate in the enzyme's cycle termed the "cleavable complex." This study aims to increase understanding of drug interactions by use of the "TARDIS" (trapped in agarose DNA immunostaining) assay to measure drug-induced topo II cleavable complexes in individual cells treated with anthracyclines. Mammalian cells contain two isoforms of topo II (alpha and beta) and the TARDIS assay enables visualisation of isoform-specific complexes. Drug-treated cells were embedded in agarose, lysed and incubated with anti-topo II antibodies to microscopically detect topo IIalpha or beta complexes. Results for K562 cells (at clinically relevant concentrations) showed that IDA and idarubicinol, its metabolite, formed mainly topo IIalpha cleavable complexes, the level of which decreases at doses > 1 microM for IDA. Our data suggest that this decrease is due to catalytic inhibition by IDA at these doses. Doxorubicin formed low levels of topo IIalpha complexes and negligible topo IIbeta complexes. In cytotoxicity studies, IDA and idarubicinol were equipotent, but both were more potent than daunorubicin and doxorubicin. We showed for the first time that there was a persistent increase in levels of topo IIalpha cleavable complexes after removal of IDA, suggesting that its greater effectiveness may be associated with both the longevity and high levels of these complexes.
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PMID:Formation and longevity of idarubicin-induced DNA topoisomerase II cleavable complexes in K562 human leukaemia cells. 1203 65

DNA topoisomerase II has been shown to be an important therapeutic target in cancer chemotherapy. Here, we describe studies on the antitumor activity of a novel topoisomerase II inhibitor, ER-37328 [12,13-dihydro-5-[2-(dimethylamino)ethyl]-4H-benzo[c]pyrimido[5,6,1- jk]carbazole-4,6,10(5H,11H)-trione hydrochloride]. ER-37328 inhibited topoisomerase II activity at 10 times lower concentration than etoposide in relaxation assay and induced double-strand DNA cleavage within 1 h in murine leukemia P388 cells, in a bell-shaped manner with respect to drug concentration. The maximum amount of DNA cleavage was obtained at 2 microM. Like etoposide, ER-37328 (2 microM) induced topoisomerase II-DNA cross-linking in P388 cells. A spectroscopic study of ER-37328 mixed with DNA demonstrated that ER-37328 has apparent binding activity to DNA. ER-37328 showed potent growth-inhibitory activity against a panel of 21 human cancer cell lines [mean (50% growth-inhibitory concentration) GI50 = 59 nM]. COMPARE analysis according to the National Cancer Institute screening protocol showed that the pattern of the growth-inhibitory effect of ER-37328 was similar to that of etoposide, but different from that of doxorubicin. Studies on etoposide-, amsacrine [4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA)]-, and camptothecin-resistant P388 cell lines showed that: (a) etoposide- and m-AMSA-resistant P388 cell lines were partially resistant to ER-37328 compared with the parental cell line; and (b) a camptothecin-resistant cell line showed no cross-resistance to ER-37328. In addition, ER-37328 overcame P-glycoprotein-mediated resistance. In vivo, ER-37328 produced potent tumor regression of Colon 38 carcinoma inoculated s.c., and its activity was superior to that of etoposide or doxorubicin. These results indicate that ER-37328 inhibits topoisomerase II activity through the formation of topoisomerase II-DNA cleavable complex and has potent antitumor activity both in vitro and in vivo.
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PMID:Antitumor activity of ER-37328, a novel carbazole topoisomerase II inhibitor. 1246 11

The MLL gene is involved in many chromosomal translocations leading to both acute myeloid and lymphoid leukemia. Some patients treated for primary malignancies with chemotherapeutic agents that inhibit DNA topoisomerase II (topo II) develop treatment-related leukemia (t-AML) caused by MLL gene rearrangement. Whether these patients are unusually susceptible to anti-topo II drugs, or whether this is a random adverse event is unknown. To discover genetic polymorphisms that may predispose patients to t-AML development, we sequenced the 8.3-kb MLL breakpoint cluster region (BCR) from 22 patients who had been treated with topo II inhibitors and who developed t-AML and from 37 patients who did not, and from eight infants and 20 normal individuals. Four polymorphic sites within Alu repetitive elements were identified; three affected the length of poly-A tracts and one altered the size of a trinucleotide repeat. The three poly-A tract polymorphisms occurred with equal frequency in leukemic patients and controls and hence are not predictors of risk. The trinucleotide GAA repeat has three alleles: (GAA)4, (GAA)5, and (GAA)6. The (GAA)6 allele is very rare. The adult t-AML patients are almost exclusively (GAA)4/5 heterozygotes (83%), whereas the normal population is only 55% (GAA)4/5 heterozygotic and is represented equally by (GAA)4 and (GAA)5 homozygotes (20% each). Only certain trends could be established because of the small sample size of these leukemic groups. Whereas adult t-AML patients are more likely to be (GAA)4/5 heterozygotes, this is not statistically significant, and this polymorphism within the MLL BCR has only a suggestive association with t-AML development.
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PMID:Polymorphisms in the MLL breakpoint cluster region (BCR). 1266 71

A high-throughput screen (HTS) was developed and used to identify inhibitors of bacterial DNA gyrase. Among the validated hits were 53 compounds that also inhibited mammalian topoisomerase II with IC(50) values of <12.5 micro g/mL for 51 of them. Using computational methods, these compounds were subjected to cluster analysis to categorize them according to their chemical and structural properties. Nine compounds from different clusters were tested for their whole-cell inhibitory activity against 3 cancer cell lines-NCI-H460 (lung), MCF7 (breast), and SF-268 (CNS)-at a concentration of 100 micro M. Five compounds inhibited cell growth by >50% for all 3 cell lines tested. These compounds were tested further against a panel of 53 to 57 cell lines representing leukemia, melanoma, colon, CNS, ovarian, renal, prostate, breast, and non-small cell lung cancers. In this assay, PGE-7143417 was found to be the most potent compound, which inhibited the growth of all the cell lines by 50% at a concentration range of 0.31 to 2.58 micro M, with an average of 1.21 micro M. An additional 17 compounds were also tested separately against a panel of 10 cell lines representing melanoma, colon, lung, mammary, ovarian, prostate, and renal cancers. In this assay, 4 compounds-PGE-3782569, PGE-7411516, PGE-2908955, and PGE-3521917-were found to have activity with concentrations for 50% cell growth inhibition in the 0.59 to 3.33, 22.5 to 59.1, 7.1 to >100, and 24.7 to >100 micro M range.
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PMID:Development and use of a high-throughput bacterial DNA gyrase assay to identify mammalian topoisomerase II inhibitors with whole-cell anticancer activity. 1284 36

Testicular cancer is the most common solid tumour among young males aged 15-35 years. Cisplatin-based combination chemotherapy has changed the outlook of this disease. Disseminated testicular cancer, once uniformly fatal, now has a cure rate of more than 80% with combination chemotherapy. Systematic randomised trials have shown that cisplatin, etoposide and bleomycin (PEB) combination chemotherapy remains the mainstay of treatment. While there is a high cure rate with chemotherapy in patients with this disease, some long-term complications from chemotherapy have now been recognised, including secondary leukaemia, therapy-related solid tumours, nephrotoxicity, neurotoxicity, pulmonary toxicity, vascular toxicity and infertility. Etoposide, a DNA topoisomerase II inhibitor, is a significant risk factor for developing leukaemia; the risk appears to be correlated with the total dose given. Patients receiving cisplatin-based combination chemotherapy for testicular cancer also appear to have a higher relative risk for developing second non-germ cell malignancies; the greatest risks for therapy-related solid tumours were seen with a combination of radiation therapy plus chemotherapy. Long-term vascular toxicities associated with chemotherapy include Raynaud's phenomenon, acute myocardial infarction and cerebrovascular events. Bleomycin is thought to be the most important drug in the pathogenesis of Raynaud's phenomenon, while cisplatin is the most likely agent involved in myocardial infarction. Peripheral neuropathy is the most common form of neurotoxicity observed with cisplatin-based chemotherapy. Risk factors for the development of neural damage include a high cumulative dose of cisplatin, the use of vinblastine and the concomitant development of Raynaud's phenomenon. Cisplatin is also well known to cause significant nephrotoxicity. Approximately 25% of patients present with azoospermia after undergoing combination chemotherapy with a follow up of 2-5 years. Physician awareness of complications associated with chemotherapy is vital to maximise efficacy, minimise toxicity, and preserve quality of life after treatment. Sperm cryopreservation should be considered for patients who desire children. Close monitoring during therapy allows for the early diagnosis of complications, and close follow up of patients after the completion of therapy is necessary to monitor for relapse and development of long-term complications such as myelodysplastic syndrome and leukaemia. Despite these complications, given the potential for cure rates in this young group of patients, the benefits far outweigh the risks.
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PMID:Long-term complications of chemotherapy for germ cell tumours. 1288 63

A series of novel 4beta-substituted sulfonamide derivatives of 4'-O-demethyl-4-desoxypodophyllotoxin has been synthesized. Their effects on human DNA topoisomerase II and, in some cases, on tubulin polymerization were evaluated. Compounds 8a, 8c, 8f, 8g, 8n, 8q, 8r, and 8s and the synthetic precursor 4 are potent topoisomerase II poisons that induce double-stranded breaks in DNA, with either improved or similar activity compared to etoposide. Only the amino precursor, compound 5, was slightly active in tubulin polymerization inhibition assays. We observed that the derivatives bearing an aromatic ring on the 4beta-sulfonamide substituent were either less cytotoxic or equivalent to the parent drug, while the sulfonamides containing an aliphatic side chain and the amino-sulfonamide derivatives, except 8d and 8g, exhibited increased cytoxicity compared to etoposide. In vivo, against the P388 leukemia and the A-549 orthotopic model of lung carcinoma, the most promising compounds were the morpholino- and the piperazino-containing sulfonamides derivatives 8r and 8s.
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PMID:Synthesis and biological activity of sulfonamide derivatives of epipodophyllotoxin. 1508 35

Childhood cancer is rare comprising less than 1% of all malignancies diagnosed each year in developed countries. Leukaemia is the commonest form of cancer in children accounting for around a third of all childhood cancer, with acute lymphoblastic leukaemia (ALL) being the most prevalent. Biologically specific subtypes of ALL and acute myeloblastic leukaemia (AML), the other major morphological type of childhood leukaemia, are characterised by chromosomal changes. Whilst over 200 genes have been associated with chromosomal translocations, to date, only MLL, TEL, and AML1 have been linked with childhood leukaemia. Interestingly, there is increasing evidence to support the theory that gene rearrangements such as these may originate in utero. As with many other human diseases, both genetic and environmental factors have been implicated in the aetiology of the disease. Although much has been documented with regard to diet, smoking, alcohol consumption and recreational and prescription drug use during pregnancy, there is no consistent evidence to support a link with any of these factors and childhood leukaemia. However, findings from studies investigating prenatal and early life exposures are often based on small numbers of cases as both the type of cancer and exposure are rare. Furthermore, accurate information relating to past exposures can be difficult to obtain and is often reliant on self-reporting. To further our understanding of the aetiology of childhood leukaemia and lymphoma, there are areas which clearly warrant investigation. These include collection of parental dietary folate data combined with genetic analysis of the folate related genes, in utero exposure to DNA topoisomerase II inhibitors, and the possible effects of assisted reproduction technology on disease susceptibility.
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PMID:Causes of childhood leukaemia and lymphoma. 1531 83

Etoposide is a DNA topoisomerase II inhibitor widely used in the treatment of a variety of malignancies that is also associated with therapy-related leukemia. The cytochrome P450 (P450)-derived catechol and quinone metabolites of etoposide may be important in the damage to the MLL (mixed lineage leukemia) gene and other genes resulting in leukemia-associated chromosomal translocations. Kinetic analysis of catechol formation by recombinant P450s was determined using liquid chromatography/selected reaction monitoring/mass spectrometry. CYP3A4 was found to play a major role in etoposide metabolism (K(m) = 77.7 +/- 27.8 microM; V(max) = 314 +/- 84 pmol of catechol/min/nmol of P450). However, CYP3A5 (K(m) = 13. 9 +/- 3.1 microM; V(max) = 19.4 +/- 0.4 pmol of catechol/min/nmol of P450) may be involved in etoposide metabolism at therapeutic concentrations of free drug. Other P450s do not appear to be involved in etoposide catechol formation. Real-time polymerase chain reaction and Western blot analysis revealed significantly increased CYP3A4 mRNA and protein levels in hepatocytes treated with 10 microM rifampicin compared with untreated cells, but only modest effects of rifampicin on CYP3A5 induction. Etoposide (40, 5, 1, and 0.25 microM) caused a slight increase in CYP3A4 mRNA in three of five batches of hepatocytes but did not result in proportionately increased CYP3A4 protein levels. At high concentrations, etoposide induced only a modest increase in CYP3A5 mRNA and protein levels in four of five batches of hepatocytes. Alternatively, coadministration of other drugs with etoposide may account for the increase in etoposide catechol formation during therapy with etoposide.
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PMID:Kinetics and regulation of cytochrome P450-mediated etoposide metabolism. 1531 41

Rearrangements involving the MLL gene on chromosome band 11q23 are a hallmark of therapy-related acute myeloid leukemias following treatment with topoisomerase II poisons including etoposide. Therapy-related and de novo genomic translocation breakpoints cluster within a well-characterized 8.3-kb fragment of MLL. Repair of etoposide-stabilized DNA topoisomerase II covalent complexes may initiate MLL rearrangements observed in patients. We used a culture system of primary human hematopoietic CD34+ cells and inverse polymerase chain reaction to characterize the spectrum of stable genomic rearrangements promoted by etoposide exposure originating within an MLL translocation hotspot in therapy-related leukemia. Alterations to the region were observed at a readily detectable frequency in etoposide-treated cells. Illegitimate repair events after minimal repair included MLL tandem duplications and translocations, with minor populations of deletions or insertions. In stably repaired cells that proliferated for 10 to 14 days, the significant majority of illegitimate events were MLL tandem duplications, and several deletions, inversions, insertions, and translocations. Thus, etoposide promotes specific rearrangements of MLL consistent with the full spectrum of oncogenic events identified in leukemic samples. Although etoposide-initiated rearrangements are frequent, only a small subset of translocations occurs in cells that proliferate significantly.
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PMID:Therapy-related acute myeloid leukemia-like MLL rearrangements are induced by etoposide in primary human CD34+ cells and remain stable after clonal expansion. 1574

Etoposide (VP-16) is a potent human DNA topoisomerase II poison, derived from 4'-demethylepipodophyllotoxin, widely used in cancer chemotherapy. Continuous efforts have driven to synthesize new related compounds, presenting decreased toxic side effects, metabolic inactivation, drug resistance, and increased water solubility. Identified structure-activity relationships have pointed out the importance of the 4beta-substitution and of the configuration of the D ring. Here we report the synthesis of two novel series of derivatives of 4'-demethylepipodophyllotoxin. The first bears a carbamate chain in the 4 position (13a-f), whereas, in the second series, in addition to this chain, the lactone ring has been modified by shifting the carbonyl from position 13 to position 11 (27a-f). Moreover, an analogue of TOP-53 having this lactone modification has also been prepared (32). From this study, structure-activity relationships were established. Compounds 13a and 27a displayed potent cytotoxic activity against the L1210 cell line (10 to 20-fold higher than VP-16) and proved to be strong topoisomerase II poisons more potent than VP-16. From preliminary in vivo investigation of both compounds against P388 leukemia and orthotopically grafted human A549 lung carcinoma, it appeared that 13a and 27a constitute promising leads for a new class of antitumor agents.
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PMID:Synthesis and biological study of a new series of 4'-demethylepipodophyllotoxin derivatives. 1565 72


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