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Methods in Enzymology 1999
Topics: Antineoplastic Agents; Aziridines; Benzoquinones; Hydroxyl Radical; Models, Chemical; Molecular Probes; Nitrogen Oxides; Oxidation-Reduction; Reproducibility of Results; Spectrometry, Fluorescence; Superoxides
PubMed: 9919523
DOI: 10.1016/s0076-6879(99)00127-5 -
Biochemistry Oct 1998Described herein are detailed hydrolytic studies of a series of aziridinyl quinones, which trap nucleophiles when protonated. This study provided a compilation of the...
Described herein are detailed hydrolytic studies of a series of aziridinyl quinones, which trap nucleophiles when protonated. This study provided a compilation of the rate constants for nucleophile trapping and of the pKa values for the protonated aziridinyl quinones. A linear free energy relationship, including the antitumor agent DZQ, as well as other synthetic quinone derivatives, was obtained as a result of this study. Protonated DZQ has the relatively high pKa value of 3.8, which explains the enhanced cross-linking of DNA by DZQ and other related aziridinyl quinones at pH 4. The literature often shows aziridinyl quinone protonation occurring at the aziridinyl nitrogen, but the dependence of pKa values on quinone substituents indicates the presence of delocalization, which must arise from O-protonation. Also investigated were the DNA alkylation reactions of protonated aziridinyl quinones. At the outset of this study, we postulated that these "hard" electrophiles would alkylate the phosphate backbone of DNA. Bulk DNA is up to 35% alkylated by protonated aziridinyl quinones as judged by the incorporation of the quinone chromophore into the DNA. The presence of phosphate alkylation was verified by a 1H-31P NMR correlation experiment with DZQ-alkylated hexamer. Our modeling studies present a new picture of DZQ alkylation of DNA, where there is competition between N(7) and phosphate alkylation. The conclusions of this part of our study are that the phosphate backbone should be considered as a possible target of any DNA-alkylating agent and that an assessment of phosphate alkylation is best made with a 1H-31P NMR correlation experiment. Finally, the benzimidazole-based aziridinyl quinone 2 was observed to undergo aziridine ring opening followed by hydrolytic removal of the aminoethyl group from the quinone ring. This reaction was used to tag the phosphate backbone of DNA with aminoethyl groups. Such tags render anionic phosphates cationic and could also be employed as points of attachment for chromophores, spin labels, or other moieties to DNA.
Topics: Alkylating Agents; Alkylation; Aziridines; Benzoquinones; DNA; Esterification; Hydrolysis; Poly dA-dT; Polydeoxyribonucleotides; Sugar Phosphates
PubMed: 9790684
DOI: 10.1021/bi981204j -
Journal of Neuro-oncology 1998
Review
Topics: Antineoplastic Agents; Aziridines; Benzoquinones; Brain Neoplasms; Cyclophosphamide; Cytotoxins; Humans; Injections, Spinal; Meningeal Neoplasms; Topotecan
PubMed: 9696375
DOI: 10.1023/a:1005944622003 -
Chemical Research in Toxicology Apr 1998The biologic functions attributed to the nucleophosphoprotein p53 have been increasing in recent years. Some studies suggested that wild type p53 is responsible for cell... (Comparative Study)
Comparative Study
The biologic functions attributed to the nucleophosphoprotein p53 have been increasing in recent years. Some studies suggested that wild type p53 is responsible for cell cycle arrest brought about as a response to exposure of mammalian cells to DNA-damaging agents. This cell cycle arrest occurs in order for cells to repair the damaged macromolecules. Extensively damaged cells are also thought to undergo apoptosis via the p53-dependent or -independent signal transduction pathways. In this study, we investigated the ability of diaziridinylbenzoquinones to increase p53 levels in the human breast cancer cell line MCF-7. Diaziquone (AZQ), an anticancer agent, and its derivatives, diaziridinequinone (DZQ) and methyldiaziridinequinone (MeDZQ), induced p53 in a dose- and time-dependent manner as measured by the electrophoretic mobility shift assay. Wild type p53 induction by AZQ was suppressed when DT-diaphorase activity was inhibited by pretreating the cells with dicumarol. Aside from their potent alkylating activity, these agents also undergo redox cycling as evidenced by oxygen consumption and the production of reactive oxygen species (ROS). Inhibition of ROS production by the antioxidant enzyme catalase reduced AZQ- and DZQ-mediated p53 induction by about 45%. Thiotepa, a non-quinone aziridine-containing agent, and 1,4-benzoquinone (p-BQ), a redox cycling quinone, increased p53 levels. The nonalkylator oxygen-radical-generating agent menadione (MD) caused p53 induction only when MCF-7 cells were allowed to recover in drug-free media. On the basis of these data, we propose that the bioreductive activation of AZQ is a prerequisite for p53 induction. Moreover, the induction of p53 by AZQ requires both the quinone and the aziridine moieties of the AZQ molecule. Although AZQ and its analogues increased p53 levels in MCF-7 cells, p53 induction in these cells may not be responsible for the apoptosis seen upon treatment of MCF-7 cells with these agents. The uncoupling of p53 induction and apoptosis is evidenced by the generation of nucleosomal DNA laddering in aziridinequinone-treated T47D cells, a breast cancer cell line bearing a p53 mutation.
Topics: Adenocarcinoma; Antineoplastic Agents; Aziridines; Benzoquinones; Breast Neoplasms; Humans; Tumor Cells, Cultured; Tumor Suppressor Protein p53
PubMed: 9548807
DOI: 10.1021/tx9701945 -
Leukemia Feb 1998A phase II trial was conducted to determine which of the three possible two-drug combinations of diaziquone, etoposide and mitoxantrone was associated with the highest... (Clinical Trial)
Clinical Trial Comparative Study Randomized Controlled Trial
An evaluation of combinations of diaziquone, etoposide and mitoxantrone in the treatment of adults with relapsed or refractory acute myeloid leukemia: results of 8722, a randomized phase II study conducted by Cancer and Leukemia Group B.
A phase II trial was conducted to determine which of the three possible two-drug combinations of diaziquone, etoposide and mitoxantrone was associated with the highest response rate in patients with relapsed or refractory acute myeloid leukemia (AML). Of the 167 patients (median age 55) with AML who entered the trial, 123 were in first relapse, 22 were in second relapse and 22 had failed to achieve complete remission (CR). CR rates were 30% for diaziquone and mitoxantrone, and 23% for the other two combinations (mitoxantrone/etoposide and diaziquone/etoposide), NS. Patients in first relapse had higher CR rates (40%) than other patients. Of the 166 patients who actually received treatment, 43 died before having either a CR or persistent leukemia. Non-hematologic toxicity was primarily mucosal with 24% of patients experiencing grade 3 or greater stomatitis on the two diaziquone arms, and 43% on the mitoxantrone/etoposide arm. The combination of diaziquone and mitoxantrone was selected for further testing in patients with AML.
Topics: Acute Disease; Adult; Aged; Antineoplastic Combined Chemotherapy Protocols; Aziridines; Benzoquinones; Etoposide; Female; Humans; Leukemia, Myeloid; Male; Middle Aged; Mitoxantrone
PubMed: 9519774
DOI: 10.1038/sj.leu.2400905 -
Analytical Chemistry Nov 1997A simple and highly sensitive method to quantify the rates of production of OH in biological systems is described. This method employs the reaction between OH and...
A simple and highly sensitive method to quantify the rates of production of OH in biological systems is described. This method employs the reaction between OH and dimethyl sulfoxide to generate quantitatively a methyl radical, which then reacts with a fluorescamine-derivatized nitroxide to produce the stable O-methylhydroxylamine. This O-methylhydroxylamine is separated by reversed-phase high-performance liquid chromatography and quantified fluorometrically. The estimated detection limit of the O-methylhydroxylamine is 3.5 nM for a 50 microL injection at a signal to noise ratio of 2. The method is applied to the determination of the rates of OH production in a biologically relevant model system and in a mouse epidermal cell line treated with a quinone anticancer compound.
Topics: Animals; Antineoplastic Agents; Aziridines; Benzoquinones; Cell Line; Hydroxyl Radical; Mice; Molecular Structure
PubMed: 9360488
DOI: 10.1021/ac970622b -
Biochemical Pharmacology Apr 1997Two versions of the comet assay have been used to identify the difference in the modes of action of AZQ (2,5-diaziridinyl-3,6-bis(carboethoxyamino)-1,4-benzoquinone) and...
Two versions of the comet assay have been used to identify the difference in the modes of action of AZQ (2,5-diaziridinyl-3,6-bis(carboethoxyamino)-1,4-benzoquinone) and BZQ (2,5-diaziridinyl-3,6-bis(ethanolamino)-1,4-benzoquinone) in human leukaemia K562 cells and a K562-derived resistant cell line, BZQR. Using the standard alkaline assay, AZQ produced dose-dependent changes in the mean comet moments from K562 cells, consistent with the formation of strand breaks. This damage was repaired over a period of 6 hr after removal of the drug. The resistant cell line, BZQR, showed much smaller changes in comet moment under identical conditions. In contrast to AZQ, BZQ did not produce any measurable strand breaks in the K562 or BZQR cells. However, the comet radiation/crosslinking assay and a fluorescence-based assay revealed that BZQ extensively cross-links DNA in K562 cells. The extent of cross-linking is greatly reduced in the resistant cell line.
Topics: Antineoplastic Agents; Aziridines; Benzoquinones; Cross-Linking Reagents; DNA Damage; DNA Repair; Drug Resistance; Electrophoresis, Agar Gel; Humans; Tumor Cells, Cultured
PubMed: 9175716
DOI: 10.1016/s0006-2952(96)00818-0 -
Blood Feb 1997This study evaluated the effect of filgrastim (granulocyte colony-stimulating factor [G-CSF]) on the duration of granulocytopenia and thrombocytopenia after intensive... (Clinical Trial)
Clinical Trial
Granulocyte-colony stimulating factor (filgrastim) accelerates granulocyte recovery after intensive postremission chemotherapy for acute myeloid leukemia with aziridinyl benzoquinone and mitoxantrone: Cancer and Leukemia Group B study 9022.
This study evaluated the effect of filgrastim (granulocyte colony-stimulating factor [G-CSF]) on the duration of granulocytopenia and thrombocytopenia after intensive consolidation therapy with diaziquone (AZO) and mitroxantrone for patients less than 60 years of age with acute myeloid leukemia (AML) in complete remission. Patients less than 60 years of age with AML who achieved complete remission (CR) with daunorubicin and cytarabine induction therapy, were scheduled to receive three sequential courses of high-dose cytarabine, cyclophosphamide/etoposide, AZQ, and mitroxantrone in a pilot study to determine their tolerance of these three sequential consolidation regimens. The initial patients treated with AZQ and mitroxantrone experienced prolonged bone marrow suppression and, therefore, subsequent cohorts were treated with G-CSF, 5 micrograms/kg, beginning the day after completion of the third cycle of chemotherapy. There was a marked decrease in the duration of granulocytopenia less than 500/microL in two groups of patients receiving two different dose levels of AZQ and the same dose of mitoxantrone compared with patients not receiving the G-CSF. There was also a decrease in the need for hospitalization, as well as the duration of hospitalization. There was a trend towards shortening of the duration of thromobocytopenia, as well. The duration of complete remission and overall survival was similar in patients who received or did not receive G-CSF. G-CSF markedly shortened the duration of granulocytopenia in patients with AML receiving intensive postremission consolidation with AZQ and mitoxantrone. There was no adverse effect on CR duration or survival.
Topics: Acute Disease; Adolescent; Adult; Antineoplastic Combined Chemotherapy Protocols; Aziridines; Benzoquinones; Bone Marrow; Female; Filgrastim; Granulocyte Colony-Stimulating Factor; Granulocytes; Humans; Leukemia, Myeloid; Leukocyte Count; Male; Middle Aged; Mitoxantrone; Pilot Projects; Platelet Count; Recombinant Proteins; Remission Induction
PubMed: 9028308
DOI: No ID Found -
Seminars in Oncology Aug 1996Controlled clinical trials indicate that amifostine (WR-2721, Ethyol) confers protection from the cumulative hematologic toxicities associated with alkylating agents and...
Controlled clinical trials indicate that amifostine (WR-2721, Ethyol) confers protection from the cumulative hematologic toxicities associated with alkylating agents and organoplatinums. To determine whether amifostine protects primitive hematopoietic progenitors from the cytotoxicity of functionally diverse antineoplastics, formation of the multipotent hematopoietic progenitors colony-forming units-granulocyte-erythroid, macrophage, megakaryocyte (CFU-GEMM) and erythroid burst-forming units (BFU-E) was evaluated using a clonogenic progenitor inhibition assay. Bone marrow mononuclear cells from normal donors were subjected to a 15-minute exposure of medium, amifostine (500 micromol/L), or WR-1065 (100 micromol/L at concentrations approximating peak plasma levels, washed twice, then treated with the antineoplastic for 1 to 6 hours. Colony growth was scored after 14 days of incubation. Amifostine conferred protection against a broader range of antineoplastics than did WR-1065. Amifostine protected CFU-GEMM against cytotoxicity from daunorubicin, mitoxantrone, and paclitaxel (range, 1.29- to 9.57-fold) (P < .05) but did not afford protection against cisplatin, diaziquone, or thiotepa. Similarly, amifostine protected BFU-E against toxicity from doxorubicin, mitoxantrone, paclitaxel, cisplatin, and diaziquone, yielding 3.4- to 65-fold greater colony recovery compared with controls. The high degree of cytoprotection afforded by amifostine derived largely from stimulation of progenitor growth at sublethal chemotherapy concentrations. In the absence of antineoplastic exposure, preincubation with amifostine or WR-1065 enhanced the colony-forming capacity of bone marrow progenitors from six normal donors, increasing recovery of CFU-GEMM and BFU-E up to sevenfold. We conclude that amifostine protects primitive hematopoietic progenitors from a wide range of antineoplastics. This broad hemoprotective effect derives in part from inherent trophic effects on progenitor growth and survival.
Topics: Amifostine; Antineoplastic Agents; Bone Marrow Cells; Cells, Cultured; Hematopoietic Stem Cells; Humans; Mercaptoethylamines
PubMed: 8783669
DOI: No ID Found -
The British Journal of Cancer.... Jul 1996The group I aziridinylquinone anti-cancer agents mitomycin C, diaziquone or trenimon were much more cytotoxic to DT-diaphorase-enriched L5178Y/HBM10 lymphoblasts than...
The group I aziridinylquinone anti-cancer agents mitomycin C, diaziquone or trenimon were much more cytotoxic to DT-diaphorase-enriched L5178Y/HBM10 lymphoblasts than parental L5178Y cells and caused little oxygen activation. Furthermore, inactivation of cellular DT-diaphorase prevented cytotoxicity whereas catalase did not affect cytotoxicity. This suggests that DT-diaphorase activated these agents and the hydroquinone formed mediated DNA alkylation, crosslinking and cytotoxicity. The group II quinone agents phenanthrenequinone, 2-amino-1, 4-naphthoquinoneimine or naphthazarin were also more cytotoxic to L5178Y/HBM10 cells than parental cells and caused considerable oxygen activation. Inactivation of DT-diaphorase, however, prevented both oxygen activation and cytotoxicity. Furthermore added catalase decreased cytotoxicity, whereas catalase inactivation enhanced cytotoxicity. This suggests that DT-diaphorase activated these agents and the hydroquinone formed caused extensive oxygen activation sufficient to cause DNA oxidative damage and cytotoxicity. The group III quinone agents menadione, 2,3-dimethoxy-1,4-naphthoquinone and 2,6-dimethoxy-benzoquinone, on the other hand, were more cytotoxic to the parental cells than L5178Y/HBM10 cells and caused less oxygen activation than group II agents. Furthermore, inactivation of DT-diaphorase enhanced cytotoxicity and prevented oxygen activation than group II agents. Oxygen activation was therefore also attributed to hydroquinone autoxidation. However catalase did not affect cytotoxicity towards parental cells. This suggests that DT-diaphorase detoxified group III quinones and that cytotoxicity may involve DNA oxidative damage by the semiquinone radicals.
Topics: Animals; Antineoplastic Agents; Catalase; DNA Damage; Dicumarol; Drug Resistance; Mice; Mitomycin; NAD(P)H Dehydrogenase (Quinone); Oxidation-Reduction; Oxygen Consumption; Quinones; Tumor Cells, Cultured
PubMed: 8763840
DOI: No ID Found