Benzene metabolites antagonize etoposide-stabilized cleavable complexes of DNA topoisomerase IIα

Abstract Chronic exposure to benzene is associated with hematotoxicity and acute myelogenous leukemia. Inhibition of topoisomerase IIα (topo II) has been implicated in the development of benzene-induced cytogenetic aberrations. The purpose of this study was to determine the mechanism of topo II inhibition by benzene metabolites. In a DNA cleavage/relaxation assay, topo II was inhibited byp-benzoquinone and hydroquinone at 10 μM and 10 mM, respectively. On peroxidase activation, inhibition was seen with 4,4′-biphenol, hydroquinone, and catechol at 10 μM, 10 μM, and 30 μM, respectively. But, in no case was cleavable complex stabilization observed and the metabolites appeared to act at an earlier step of the enzyme cycle. In support of this conclusion, several metabolites antagonized etoposide-stabilized cleavable complex formation and inhibited topo II–DNA binding. It is therefore unlikely that benzene-induced acute myelogenous leukemia stems from events invoked for leukemogenic topo II cleavable complex-stabilizing antitumor agents.

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Topoisomerase II levels and drug sensitivity in adult acute myelogenous leukemia

Blood ◽

10.1182/blood.v83.2.517.517 ◽

1994 ◽

Vol 83 (2) ◽

pp. 517-530 ◽

Cited By ~ 71

Author(s):

SH Kaufmann ◽

JE Karp ◽

RJ Jones ◽

CB Miller ◽

E Schneider ◽

...

Keyword(s):

Acute Myelogenous Leukemia ◽

Topoisomerase Ii ◽

Drug Sensitivity ◽

Myelogenous Leukemia ◽

Clinical Samples ◽

Immunoperoxidase Staining ◽

Acute Myelogenous ◽

Topo Ii

Abstract The topoisomerase (topo) II-directed agents etoposide, daunorubicin (DNR), and amsacrine (m-AMSA) are widely used in the treatment of acute myelogenous leukemia (AML). In the present study, multiple aspects of topo II-mediated drug action were examined in marrows from adult AML patients. Colony-forming assays revealed that the dose of etoposide, DNR, or m-AMSA required to diminish leukemic colony formation by 90% (LD90) varied over a greater than 20-fold range between different pretreatment marrows. Measurement of nuclear DNR accumulation in the absence and presence of quinidine revealed evidence of P-glycoprotein (Pgp) function in 8 of 82 samples at diagnosis and 5 of 36 samples at first relapse, but the largest quinidine-induced increment in DNR accumulation (< 2-fold) was too small to explain the variations in drug sensitivity. Restriction enzyme-based assays and sequencing of partial topo II alpha and topo II beta cDNAs from the most highly resistant specimens failed to demonstrate topo II gene mutations that could account for resistance. Western blotting of marrow samples containing greater than 80% blasts revealed that the content of the two topo II isoenzymes varied over a greater than 20-fold range, but did not correlate with drug sensitivity in vitro or in vivo. In addition, levels of topo II alpha and topo II beta in 46 of 47 clinical samples were lower than in human AML cell lines. Immunoperoxidase staining showed that these low topo II levels were accompanied by marked cell-to- cell heterogeneity, with topo II alpha being abundant in some blasts and diminished or absent from others. There was a trend toward increasing percentages of topo II alpha-positive cells in pretreatment marrows that contained more S-phase cells. Consistent with this observation, treatment of patients with granulocyte-macrophage colony- stimulating factor for 3 days before chemotherapy resulted in increases in topo II alpha-positive cells concomitant with increases in the number of cells traversing the cell cycle. These observations have implications for the regulation of topo II in AML, for the use of topo II-directed chemotherapy, and for future attempts to relate drug sensitivity to topo II levels in clinical material.

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Treatment-Related Myelodysplastic Syndrome and Acute Myelogenous Leukemia in Patients Treated With Ibritumomab Tiuxetan Radioimmunotherapy

Journal of Clinical Oncology ◽

10.1200/jco.2006.09.2882 ◽

2007 ◽

Vol 25 (27) ◽

pp. 4285-4292 ◽

Cited By ~ 98

Author(s):

Myron S. Czuczman ◽

Christos Emmanouilides ◽

Mohamed Darif ◽

Thomas E. Witzig ◽

Leo I. Gordon ◽

...

Keyword(s):

Myelodysplastic Syndrome ◽

Acute Myelogenous Leukemia ◽

Chromosomal Abnormalities ◽

Alkylating Agents ◽

Nucleoside Analogs ◽

Myelogenous Leukemia ◽

Compassionate Use ◽

Ibritumomab Tiuxetan ◽

Cytogenetic Aberrations ◽

Acute Myelogenous

PurposeTo investigate the incidence of treatment-related myelodysplastic syndrome (t-MDS) and treatment-related acute myelogenous leukemia (t-AML) after treatment with ibritumomab tiuxetan radioimmunotherapy.Patients and MethodsAnalysis of the incidence of t-MDS and t-AML in 746 patients with non-Hodgkin's lymphoma (NHL) treated with the ibritumomab tiuxetan regimen in registration and compassionate-use trials between 1996 and 2002.ResultsNineteen patients (2.5%) developed t-MDS or t-AML at a median follow-up of 4.4 years (range, 0 to 9.3). These malignancies were diagnosed at a median of 5.6 years (range, 1.4 to 13.9) after the diagnosis of NHL and 1.9 years (range, 0.4 to 6.3) after radioimmunotherapy. The annualized rates were 0.3% per year after the diagnosis of NHL and 0.7% per year after treatment. Most patients with t-MDS or t-AML had multiple cytogenetic aberrations, commonly on chromosomes 5 and 7, suggesting an association with previous exposure to chemotherapy.ConclusionAnalysis of data from patients in registration and compassionate-use trials suggests that the annualized incidences of t-MDS and t-AML are consistent with that expected in patients with NHL who have had extensive previous chemotherapy treatment and do not appear to be increased after treatment with the ibritumomab tiuxetan regimen. Cytogenetic testing before treatment with radioimmunotherapy may identify existing chromosomal abnormalities in previously treated patients, particularly those who have been treated with alkylating agents and purine nucleoside analogs and would be at higher risk for t-MDS or t-AML.

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Topoisomerase II levels and drug sensitivity in adult acute myelogenous leukemia

Blood ◽

10.1182/blood.v83.2.517.bloodjournal832517 ◽

1994 ◽

Vol 83 (2) ◽

pp. 517-530 ◽

Cited By ~ 2

Author(s):

SH Kaufmann ◽

JE Karp ◽

RJ Jones ◽

CB Miller ◽

E Schneider ◽

...

Keyword(s):

Acute Myelogenous Leukemia ◽

Topoisomerase Ii ◽

Drug Sensitivity ◽

Myelogenous Leukemia ◽

Clinical Samples ◽

Immunoperoxidase Staining ◽

Acute Myelogenous ◽

Topo Ii

The topoisomerase (topo) II-directed agents etoposide, daunorubicin (DNR), and amsacrine (m-AMSA) are widely used in the treatment of acute myelogenous leukemia (AML). In the present study, multiple aspects of topo II-mediated drug action were examined in marrows from adult AML patients. Colony-forming assays revealed that the dose of etoposide, DNR, or m-AMSA required to diminish leukemic colony formation by 90% (LD90) varied over a greater than 20-fold range between different pretreatment marrows. Measurement of nuclear DNR accumulation in the absence and presence of quinidine revealed evidence of P-glycoprotein (Pgp) function in 8 of 82 samples at diagnosis and 5 of 36 samples at first relapse, but the largest quinidine-induced increment in DNR accumulation (< 2-fold) was too small to explain the variations in drug sensitivity. Restriction enzyme-based assays and sequencing of partial topo II alpha and topo II beta cDNAs from the most highly resistant specimens failed to demonstrate topo II gene mutations that could account for resistance. Western blotting of marrow samples containing greater than 80% blasts revealed that the content of the two topo II isoenzymes varied over a greater than 20-fold range, but did not correlate with drug sensitivity in vitro or in vivo. In addition, levels of topo II alpha and topo II beta in 46 of 47 clinical samples were lower than in human AML cell lines. Immunoperoxidase staining showed that these low topo II levels were accompanied by marked cell-to- cell heterogeneity, with topo II alpha being abundant in some blasts and diminished or absent from others. There was a trend toward increasing percentages of topo II alpha-positive cells in pretreatment marrows that contained more S-phase cells. Consistent with this observation, treatment of patients with granulocyte-macrophage colony- stimulating factor for 3 days before chemotherapy resulted in increases in topo II alpha-positive cells concomitant with increases in the number of cells traversing the cell cycle. These observations have implications for the regulation of topo II in AML, for the use of topo II-directed chemotherapy, and for future attempts to relate drug sensitivity to topo II levels in clinical material.

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Acute Myelogenous Leukemia After Treatment for Malignant Germ Cell Tumors in Children

Journal of Clinical Oncology ◽

10.1200/jco.1999.17.10.3226 ◽

1999 ◽

Vol 17 (10) ◽

pp. 3226-3233 ◽

Cited By ~ 42

Author(s):

Dominik T. Schneider ◽

Elisabeth Hilgenfeld ◽

Dirk Schwabe ◽

Wolfgang Behnisch ◽

Andreas Zoubek ◽

...

Keyword(s):

Germ Cell ◽

Acute Myelogenous Leukemia ◽

Topoisomerase Ii ◽

Germ Cell Tumors ◽

Myelogenous Leukemia ◽

Cytogenetic Aberrations ◽

Kaplan Meier ◽

Increased Risk ◽

Acute Myelogenous ◽

Malignant Germ Cell Tumors

PURPOSE: To identify the long-term sequelae of therapy for malignant germ cell tumors (GCTs). PATIENTS AND METHODS: Between 1980 and 1998, 1,132 patients were prospectively enrolled onto the German nontesticular GCT studies. A total of 442 patients received chemotherapy using combinations of the drugs cisplatin, ifosfamide, etoposide, vinblastine, and bleomycin, and 174 patients were treated with a combination of chemotherapy and radiotherapy. Median follow-up duration was 38 months (range, 6 to 199 months). RESULTS: Six patients developed therapy-related acute myelogenous leukemia (t-AML). There was no t-AML among patients treated with surgery (n = 392) or radiotherapy only (n = 124). The Kaplan-Meier estimates of the cumulative incidence (at 10 years) of t-AML were 1.0% for patients treated with chemotherapy (three of 442) and 4.2% for patients treated with combined chemotherapy and radiotherapy (three of 174). Notably, four of these six patients had been treated according to a standard protocol with modest cumulative chemotherapy doses. Five patients had received less than 2 g/m2 epipodophyllotoxins, and four patients had received less than 20 g/m2 ifosfamide. Four patients presented with AML, two with myelodysplasia in transformation to AML. In five patients, cytogenetic aberrations were found, four of which were considered characteristic for t-AML. Four patients died despite antileukemic therapy. One patient is alive but suffered a relapse of his GCT, and one patient is alive and well. No secondary solid neoplasm was observed. CONCLUSION: In patients with AML after treatment for GCT, several pathogenetic mechanisms must be considered. AML might evolve from a malignant transformation of GCT components without any influence of the chemotherapy. On the other hand, the use of alkylators and topoisomerase II inhibitors is associated with an increased risk of t-AML. Future studies will show if the reduction of treatment intensity in the current protocol reduces the risk of secondary leukemia in these patients.

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