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Ultrasound in Medicine & Biology 1996We investigated in vitro enhancement of cytotoxicity of chemotherapeutic agents by tone-burst ultrasound. Survival of CHO cell exposed to chemotherapeutic agents in...
We investigated in vitro enhancement of cytotoxicity of chemotherapeutic agents by tone-burst ultrasound. Survival of CHO cell exposed to chemotherapeutic agents in culture medium was determined with and without insonation (1.62 and 0.29 MHz, 10% duty cycle). Insonations up to 0.4 MPa peak pressure (5 kW/m2 spatial and temporal average) occurred in the middle of 1 h drug exposures. Cytotoxicity in ultrasound control groups was never observed. Ultrasound increased the clonogenic cytotoxicity of adriamycin (p = 0.00027 by paired t test) and diaziquone but not of cisplatin or mitomycin C. Potentiation of adriamycin depended on exposure time and tone-burst frequency. .OH production in water occurred at intensities as low as 0.4 kW/m2, but did not increase with added adriamycin. Ultrasound did not affect membrane fluidity, but moderately increased cellular adriamycin accumulation, possibly explaining the observed drug potentiation.
Topics: Animals; Antibiotics, Antineoplastic; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Aziridines; Benzoquinones; CHO Cells; Cell Culture Techniques; Cell Survival; Cisplatin; Cricetinae; Doxorubicin; Drug Synergism; Flow Cytometry; Hydroxyl Radical; Membrane Fluidity; Mitomycin; Ultrasonography
PubMed: 8783468
DOI: 10.1016/0301-5629(95)02053-5 -
Biochemical Pharmacology Aug 1995Two resistant K562 sublines have been developed by treatment with AZQ (2,5-bis(carboethoxyamino)-3,6-diaziridinyl-1,4-benzoquinone) and BZQ... (Comparative Study)
Comparative Study
Two resistant K562 sublines have been developed by treatment with AZQ (2,5-bis(carboethoxyamino)-3,6-diaziridinyl-1,4-benzoquinone) and BZQ (2,5-bis(2-hydroxyethylamino)-3,6-diaziridinyl-1,4-benzoquinone). The ID50 values of for AZQ on K562, the AZQ-resistant sublines (AZQR) and the BZQ-resistant sublines (BZQR) were 0.063, 1.47 and 0.244 microM, respectively. The relative ID50 values for BZQ on the same cell lines were 0.2, 0.67 and 0.83 microM, respectively. Although it is generally believed that these two quinones function by different mechanisms, the two sublines have similar decreased levels of cytochrome P-450 reductase and DT-diaphorase and increased levels of glutathione and superoxide dismutase, compared to the parent cell line. The sublines are also cross-resistant to adriamycin, mitozolamide, N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and mitomycin C. This work indicates the potential multifactorial mechanisms by which drug resistance can be induced in cell lines in the absence of conventional 'P'-glycoprotein multidrug resistance.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Aziridines; Benzoquinones; Cell Division; Cell Line; Dose-Response Relationship, Drug; Drug Resistance; Glutathione; Humans; NAD(P)H Dehydrogenase (Quinone); NADPH-Ferrihemoprotein Reductase; Oxidoreductases; Superoxide Dismutase
PubMed: 7646550
DOI: 10.1016/0006-2952(95)00155-s -
Anticancer Research 1995Murine NIH 3T3 cells were stably transfected with human NQO1 (DT-diaphorase) cDNA and clonal cell lines with up to 15-fold elevated DT-diaphorase activity were obtained....
Over-expression of DT-diaphorase in transfected NIH 3T3 cells does not lead to increased anticancer quinone drug sensitivity: a questionable role for the enzyme as a target for bioreductively activated anticancer drugs.
Murine NIH 3T3 cells were stably transfected with human NQO1 (DT-diaphorase) cDNA and clonal cell lines with up to 15-fold elevated DT-diaphorase activity were obtained. These cell lines showed no significant increase in cell growth inhibition by the quinone anticancer drugs mitomycin C, diaziquone and menadione, when compared to vector alone transfected control cells. There was a small increase in sensitivity to doxorubicin. The relative increase in DT-diaphorase activity in the transfected cells compared to the control cell lines is similar to the increase of DT-diaphorase activity found in some human tumors compared to their paired normal tissue. The results of this study, and other evidence, suggests that DT-diaphorase may not, as suggested by others, be a clinically useful target for the bioreductive activation of anticancer drugs.
Topics: 3T3 Cells; Animals; Antineoplastic Agents; Aziridines; Benzoquinones; Doxorubicin; Humans; Mice; Mitomycin; NAD(P)H Dehydrogenase (Quinone); Transfection; Vitamin K
PubMed: 7653992
DOI: No ID Found -
Chemical Research in Toxicology 1995The antitumor agent diaziquone (AZQ) reacts with reduced glutathione (GSH) in aqueous solutions and under aerobic conditions to give rise to the glutathionyl and...
The antitumor agent diaziquone (AZQ) reacts with reduced glutathione (GSH) in aqueous solutions and under aerobic conditions to give rise to the glutathionyl and hydroxyl free radicals, as well as the AZQ semiquinone. Under anaerobic conditions, the only radical observed was the glutathionyl radical. These radicals are quickly abrogated when superoxide dismutase and catalase are coincubated. Separately, superoxide dismutase favors the formation of thiyl radicals while catalase favors the formation of hydroxyl radicals and AZQ semiquinone. The metal chelator diethylenetriaminepentaacetic acid favors the production of hydroxyl radicals and AZQ semiquinone. The reaction of AZQ with GSH at pH 7.2 and 5.5 results in a variety of conjugates. These conjugates include addition of glutathione to both aziridines, displacement of the aziridines by GSH, and a combination of both. The majority of the conjugates are formed by nucleophilic attack of GSH to the AZQ aziridines or by 1,4-Michael addition to the AZQ quinone or a combination of both. There may be a small free radical component in conjugate formation, but the majority of the free radicals observed are from redox reactions that involve the oxidation of glutathione and the reduction and autoxidation of AZQ to produce oxygen radicals and hydrogen peroxide, a process that is enhanced by trace metal ions.
Topics: Antineoplastic Agents; Antioxidants; Aziridines; Benzoquinones; Catalase; Drug Interactions; Electron Spin Resonance Spectroscopy; Free Radicals; Glutathione; Oxygen Consumption; Superoxide Dismutase
PubMed: 7578933
DOI: 10.1021/tx00045a018 -
Investigational New Drugs 1995Diaziquone (AZQ) is a lipid soluble alkylating agent which was designed for increased CNS penetration. Its principle toxicity is myelosuppression. We conducted a phase I... (Clinical Trial)
Clinical Trial
Diaziquone (AZQ) is a lipid soluble alkylating agent which was designed for increased CNS penetration. Its principle toxicity is myelosuppression. We conducted a phase I trial using AZQ in combination with GM-CSF to determine if the maximal tolerate dose (MTD) of AZQ could be escalated. Using GM-CSF on a standard schedule, we were unable to escalate the previously determined MTD of diaziquone with the use of this colony stimulating factor.
Topics: Antineoplastic Agents; Aziridines; Benzoquinones; Blood Platelets; Bone Marrow; Colorectal Neoplasms; Dose-Response Relationship, Drug; Drug Therapy, Combination; Drugs, Investigational; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Infusions, Intravenous; Injections, Subcutaneous; Melanoma; Neutrophils
PubMed: 8617583
DOI: 10.1007/BF00872869 -
Journal of Neuro-oncology 1995Chemotherapy for brain tumors remains unsatisfactory. Despite increasing participation in clinical trials, there is a clear need for pre-clinical models....
Chemotherapy for brain tumors remains unsatisfactory. Despite increasing participation in clinical trials, there is a clear need for pre-clinical models. Heterotransplantation of surgical specimens directly into the anterior chamber of the nude mouse eye has been demonstrated to produce evaluable xenografts. Drug access in this model is considered to mimic the blood-brain barrier. Five clinical specimens in 3 children with primitive neuroectodermal tumor/medulloblastoma were the sources of 293 intraocular xenografts (5 cohorts by source). Each tumor-bearing mouse received 1 of 5 drugs or normal saline, by intraperitoneal injection, weekly for 5 weeks. Response was monitored for up to 22 weeks, using a staging system which estimates the proportion of the anterior chamber filled by tumor. Results were analysed both as response rates (shrinkage in excess of 50%) at the conclusion of the treatment course and as time to tumor progression by the life table method. Comparison of response rates within cohorts by source of xenografts (exact chi-square test for overall and 2-sided Fisher's exact test for paired comparisons) indicated cyclophosphamide to be the most effective single agent. In logrank analyses cyclophosphamide achieved significantly longer delays to progression than all other drugs in one cohort and longer delays than all but diaziquone in 2 other cohorts. The intraocular xenograft model is a clinically relevant system for the study of therapeutic agents in brain tumors. The effectiveness of intensive dosage cyclophosphamide in a model dependent on access across the blood-aqueous barrier is important and consistent with recent clinical data.
Topics: Animals; Antineoplastic Agents; Brain Neoplasms; Cerebellar Neoplasms; Child, Preschool; Eye; Humans; Male; Medulloblastoma; Mice; Mice, Nude; Neuroectodermal Tumors, Primitive, Peripheral; Transplantation, Heterologous; Transplantation, Heterotopic
PubMed: 8523088
DOI: 10.1007/BF01054721 -
Chemical Research in Toxicology 1994The products of the alkylation reaction of reduced 2,5-bis(1-aziridinyl)-3,6-bis(carbethoxyamino)-1,4-benzoquinone (AZQ, 1a) with duplex DNA were studied using calf...
DNA-DNA interstrand cross-linking by 2,5-bis(1-aziridinyl)-3,6-bis(carbethoxyamino)-1,4-benzoquinone: covalent structure of the dG-to-dG cross-links in calf thymus DNA and a synthetic DNA duplex.
The products of the alkylation reaction of reduced 2,5-bis(1-aziridinyl)-3,6-bis(carbethoxyamino)-1,4-benzoquinone (AZQ, 1a) with duplex DNA were studied using calf thymus DNA and a synthetic oligodeoxynucleotide. Reaction of calf thymus DNA with a mixture of AZQ and ascorbic acid followed by enzymatic digestion of the sugar phosphate backbone afforded numerous AZQ-derived products including substances identified as monoadducts of AZQ with both dG and dA (with the former in greater abundance) and two diadducts, as would be expected for intrastrand or interstrand cross-links, with one containing two dG residues per AZQ and the other one each of dG and dA (with the former adduct in greater abundance). The nucleotide connectivity and covalent structure of the dG-to-dG interstrand cross-links were studied in greater detail using a synthetic DNA duplex containing the nucleotide sequence 5'-d(GGGCCC), where it appeared that the predominant interstrand cross-links bridged dG residues on opposite strands and were separated by two intervening base pairs [5'-d(GNNC)]. The covalent structure of this lesion was tentatively identified as 2b, in which the N7 atoms of two dG residues have been alkylated by the aziridine functions of AZQ, based upon the results of piperidine fragmentation and characterization of the enzymatic and acidic hydrolysates of the cross-linked DNA.
Topics: Alkylation; Animals; Aziridines; Base Sequence; Benzoquinones; Cattle; Cross-Linking Reagents; DNA; Deoxyguanosine; Formamides; Models, Molecular; Molecular Sequence Data; Piperidines; Spectrophotometry, Ultraviolet; Thymus Gland
PubMed: 7841346
DOI: 10.1021/tx00041a012 -
Cancer Research Jun 1994The metabolisms of two standard electron acceptors and a series of bioreductive antitumor compounds by purified rat and human DT-diaphorases (DTD) were compared. DTD was... (Comparative Study)
Comparative Study
The metabolisms of two standard electron acceptors and a series of bioreductive antitumor compounds by purified rat and human DT-diaphorases (DTD) were compared. DTD was purified from rat liver cytosol and from Escherichia coli in which rat liver or human lung tumor DTD complementary DNA was expressed. Km and kcat values for menadione and 2,6-dichlorophenolindophenol reduction were similar for the three enzyme preparations except that rat E. coli DTD had 2-3-fold higher kcat values for both menadione and 2,6-dichlorophenolindophenol and a 2-3-fold higher Km for menadione than either rat liver or human E. coli DTD. Reduction of the antitumor compounds was 1.9-4.9 times faster with rat E. coli DTD than with human E. coli DTD. The antitumor compounds were reduced in the following order by rat E. coli DTD: 2,5-dimethyl-3,6-diaziridinyl-1,4-benzoquinone > streptonigrin > mitomycin A > diaziquone > mitomycin C (MC) > 5-(aziridin-1-yl)-2,4-dinitrobenzamide. The order was the same for human E. coli DTD with one exception; diaziquone was reduced slightly faster than mitomycin A. Metabolism of doxorubicin could not be detected using rat or human E. coli DTD. MC-induced DNA cross-linking was also more efficient using rat E. coli DTD relative to human E. coli DTD. Metabolism of MC by rat and human E. coli DTD was also compared under aerobic and hypoxic conditions. Rates of reduction of MC and metabolite formation were similar under aerobic and hypoxic conditions, and the toxicity of MC to DTD-rich HT-29 cells was also similar in aerobic and hypoxic conditions. In contrast, the toxicity of MC to DTD-deficient BE cells was potentiated markedly under hypoxia. These data show that although small catalytic differences between rat and human E. coli DTD can be observed, compounds such as 2,5-dimethyl-3,6-diaziridinyl-1,4-benzoquinone and streptonigrin are still excellent substrates for the human enzyme and may be useful in the therapy of tumors high in DTD activity. In addition, metabolism of MC by rat and human E. coli DTD was similar in aerobic and hypoxic conditions; in agreement with these data, cytotoxicity of MC to a DTD-rich cell line was oxygen independent. Increased MC cytotoxicity under hypoxia appears to be mediated by enzymes other than DTD.
Topics: Aerobiosis; Animals; Antineoplastic Agents; Biotransformation; Carcinoma, Non-Small-Cell Lung; Cell Hypoxia; Chromatography, High Pressure Liquid; DNA Damage; DNA, Neoplasm; Escherichia coli; Humans; Kinetics; Lung Neoplasms; Mitomycin; NAD; NAD(P)H Dehydrogenase (Quinone); Oxidation-Reduction; Rats; Rats, Sprague-Dawley; Transfection; Tumor Cells, Cultured
PubMed: 8205540
DOI: No ID Found -
Annals of Oncology : Official Journal... May 1994The EORTC New Drug Development Office has initiated a multicenter collaborative program to evaluate the use of human tumor xenografts to predict phase II clinical...
BACKGROUND
The EORTC New Drug Development Office has initiated a multicenter collaborative program to evaluate the use of human tumor xenografts to predict phase II clinical activity. A first study confirmed the efficacy of doxorubicin and inactivity of amsacrine against human tumor xenografts (Boven et al., Cancer Res: 52, 5940, 1992). In the follow-up study reported here, the activities of cisplatin, AZQ (diaziquone), pazelliptine and retelliptine have been evaluated against a panel of 40 established tumor lines grown subcutaneously in nude mice.
DESIGN
The xenografts used represent carcinomas of the breast, colon, head+neck, ovary, small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC) and melanoma. Drugs were administered intravenously on days 0 and 7. Doses were for cisplatin 5 mg/kg, AZQ 3-7 mg/kg, pazelliptine 20-80 mg/kg and retelliptine 6-12.5 mg/kg and were selected to give a median loss of about 10%-15% body weight.
RESULTS
When activity was defined as a specific growth delay > 1 and a tumor growth inhibition > 50%, then cisplatin demonstrated activity in 15 of 40 xenografts tested (3 of 5 breast, 1 of 6 colon, 0 of 5 head+neck, 2 of 6 NSCLC, 4 of 7 SCLC, 1 of 5 melanoma and 4 of 6 ovarian cancers); AZQ was active in 23 of 38 xenografts (2 of 3 breast, 2 of 7 colon, 4 of 5 head+neck, 3 of 6 NSCLC, 6 of 6 SCLC, 2 of 5 melanoma, 4 of 6 ovarian cancers); pazelliptine was active in 2 of 38 xenografts (1 of 5 breast cancers, 1 of 5 melanoma) while retelliptine was active in 1 of 39 xenografts (a breast cancer xenograft) tested.
CONCLUSIONS
These results are reasonably consistent with the clinical activity of cisplatin, but overpredict the clinical efficacy of AZQ. Since pazelliptine and retelliptine are investigational compounds, the clinical phase II studies will provide a prospective test for this model. The results of the present study and the previous one indicate that the human tumor xenograft model could be suitable for predicting the activity of novel compounds to be developed for treatment of cancer patients.
Topics: Animals; Antineoplastic Agents; Aziridines; Benzoquinones; Cisplatin; Drug Screening Assays, Antitumor; Ellipticines; Europe; Female; Follow-Up Studies; Humans; Indoles; Isoquinolines; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Transplantation
PubMed: 8075048
DOI: 10.1093/oxfordjournals.annonc.a058872 -
Journal of Microencapsulation 1994We studied the liposome formulation characteristics of eight new lipophilic antitumour agents that have demonstrated a broad spectrum of antitumour activity in...
We studied the liposome formulation characteristics of eight new lipophilic antitumour agents that have demonstrated a broad spectrum of antitumour activity in preclinical in vitro and in vivo screening models. Multilamellar vesicles were prepared by using standard evaporation/hydration methods. The drug to lipid weight ratio was 1:15 in all cases. Different combinations of DMPC, DMPG and cholesterol were used. The quality of the liposomal formulations was evaluated by calculating the percentage drug bound to the liposome phase and assessing the morphology of the liposome phase by optic microscopy, to rule out the presence of drug crystals or drug/lipid microaggregates. Good liposomal preparations were obtained with hexamethylmelamine, penclomedine, mitindomide, and fazarabine. However, with taxol, batracylin, trimelamol, and diaziquone, the presence of crystals of free drug or microaggregates of lipid/drug complex was observed in all preparations, independently of lipid composition. In general, mixtures of DMPC:DMPG at a molar ratio between 7:3 and 9:1, and the addition of 5 per cent cholesterol (w/w) gave the optimal results. In vitro cytotoxicity studies of free and liposomal drugs against L1210 cells showed changes in both directions after liposome entrapment, thus suggesting that liposome entrapment may alter drug cellular uptake or may result in chemical modifications of the entrapped drug. Because of the limited number of compounds studied we were unable to identify general chemical characteristics required for an enhanced liposome formation and drug entrapment.
Topics: Animals; Antineoplastic Agents; Chemistry, Pharmaceutical; Cholesterol; Dimyristoylphosphatidylcholine; Drug Carriers; Drug Screening Assays, Antitumor; Leukemia L1210; Liposomes; Phosphatidylglycerols
PubMed: 8064554
DOI: 10.3109/02652049409040460