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Structural studies of of "active complex" of bleomycin: assignment of ligands to the ferrous ion in a ferrous-bleomycin-carbon monoxide complex.

Proton NMR studies at 360 MHz establish the binary Fe(II)-bleomycin complex to be paramagnetic with a spectrum covering 70 ppm. Addition of carbon monoxide generates a stable, diamagnetic Fe(II)-bleomycin-CO complex that is a putative structural analog of the "active" Fe(II)-bleomycin-O2 complex. The following six groups have been determined to be coordinated to the Fe(II) ion from analysis of the highly resolved 1H NMR spectra of this complex: CO, the primary and secondary amine nitrogens of the beta-aminoalanine moiety, the carbamoyl moiety on the 3-position of mannose, the pyrimidine N-1, and the imidazole N-1. The Fe(II)-bleomycin-CO complex binds to DNA, as shown by fluorescence quenching experiments, but Fe(II)-bleomycin-CO does not mediate thymine release. These results necessitate a major revision in the current model for metal coordination to bleomycin.

Bleomycin↗

A randomized trial of cisplatin, etoposide and bleomycin (PEB) versus carboplatin, etoposide and bleomycin (CEB) for patients with 'good-risk' metastatic non-seminomatous germ cell tumors.

BACKGROUND: Cisplatin-based combination chemotherapy will cure 70% to 80% of patients with metastatic non-seminomatous germ cell tumors but is associated with the possibility of severe neuro-, oto- and nephro-toxicities. Carboplatin, a cisplatin analogue, is an active drug in testicular cancer with a more favourable spectrum of side effects. In a randomized trial, the German Testicular Cancer Study Group compared a combination regimen of carboplatin, etoposide and bleomycin (CEB) to standard cisplatin, etoposide and bleomycin (PEB) chemotherapy for patients with 'minimal-' and moderate-disease' non-seminomatous germ cell tumors, according to the Indiana University classification. PATIENTS AND METHODS: PEB was given for three cycles at standard doses (given days 1-5), and the CEB regimen consisted of carboplatin (target AUC of 5 mg/ml x min) on day 1, etoposide 120 mg/m2 on days 1 to 3 and bleomycin 30 mg on days 1, 8 and 15. Four cycles of CEB were given, with the omission of bleomycin in the fourth cycle. Thus, the cumulative doses of etoposide and bleomycin applied in the two treatment arms were comparable. Fifty-four patients were entered on the trial, 29 were treated with PEB and 25 with CEB chemotherapy. Patients were stratified according to disease extent (minimal versus moderate) and the degree of tumor marker elevation. Thirty-two patients (59%) belonged to the group with minimal disease and low markers. RESULTS: No significant difference in response to chemotherapy was seen between the two arms, with CR rates of 81% for the PEB arm and 76% for CEB treatment. However, more patients treated with CEB (32% versus 13%) have relapsed after therapy, and 4 patients (16%) have died of disease progression after CEP in contrast to 1 (3%) after PEB therapy. The first interim analysis of negative events (relapse, vital tumor at secondary resection, death from disease and therapy-associated death) showed a significantly higher rate after CEB than after PEB therapy, and the trial was terminated early. After a median follow-up of 33 months for all patients, the calculation of negative events is still significantly in favour of PEB-treated patient, particularly since three late relapses > 2 years have been observed in the CEB arm (P = 0.03). CONCLUSION: This randomized trial demonstrates that even with the use of adequate doses of etoposide and full-dose bleomycin, carboplatin cannot altogether replace cisplatin in patients with testicular cancer. Treatment with the PEB regimen remains the standard approach in patients with 'good-risk' non-seminomatous germ cell tumors.

Adolescent↗

Work in progress: the effect of heat on bleomycin cytotoxicity in vitro and on the accumulation of 57Co-bleomycin in heat-treated rat tumors.

The cytotoxic effects of the sequence and timing in combined hyperthermia and bleomycin treatment were tested in vitro using V79 Chinese hamster cells. The order of treatment was important; heat treatment followed by the administration of bleomycin yielded greater cytotoxicity than when the opposite order was used. To determine whether heat-treated tumors have an altered uptake of bleomycin, rat rhabdomyosarcoma (BA 1112) tumors were heated locally with RF current (43 degrees C, 90 min.), injected with 57Co-bleomycin, and imaged on a radioisotope camera. Results of tumor-to-background (T/B) ratio analysis indicate that (a) local hyperthermia (43 degrees C) does not appear to alter tumor uptake patterns of 57Co-bleomycin; and (b) intravenous and intraperitoneal injections produce similar T/B uptake ratios, typically between 2 and 3 at 120 minutes postinjection. In the BA 1112/WAG/Rij tumor system, local hyperthermia treatment does not seem to interfere with the subsequent accumulation of bleomycin in the tumor.

Animals↗

Effect of bleomycin, neocarzinostatin, and hydroxyurea on the preformed carrageenin granuloma in rats: mechanism of hyaluronic acid accumulation by bleomycin.

In order to elucidate whether the effects of bleomycin on the production or accumulation of intercellular substances by rat carrageenin granuloma are specific to bleomycin or a general response of the granulomatous tissue to the substances interfering with DNA synthesis, we examined the wet (or dry) weight and various components (DNA and glycosaminoglycans) in the granulomatous tissue of rats treated with bleomycin, neocarzinostatin, or hydroxyurea. The changes in various parameters of the granuloma after withdrawal of the inhibitors of DNA synthesis were different with different inhibitors tested. The highest recovery rate of DNA contents in the granulomatous tissue observed after withdrawal of bleomycin. It was also found that bleomycin caused much higher accumulation of hyaluronic acid in rat carrageenin granuloma than neocarzinostatin or hydroxyurea. This accumulation mechanism was indicated to be the results of the inhibition of mucopolysaccharidase activities via cells rather than those of the stimulation of glycosaminoglycan synthesis. These findings obtained in our experimental granuloma-system are of particular importance in considering the mechanism of the side effects of bleomycin.

Animals↗

Synthetic analogues and biosynthetic intermediates of bleomycin. Metal-binding, dioxygen interaction, and implication for the role of functional groups in bleomycin action mechanism.

In order to clarify the role of bleomycin functional groups in action mechanism, the metal-binding, dioxygen activation, and DNA cleavage of several synthetic analogues and biosynthetic intermediates of bleomycin have been investigated. The present results support that 1) the beta-aminoalaninepyrimidine-beta-hydroxyhistidine portion of the bleomycin molecule substantially participates in the Fe(II) and dioxygen interactions, 2) the transposition of the pyrimidine (or pyridine) and imidazole groups in the Fe(II)-coordination is essential for the effective binding and activation of molecular oxygen by the bleomycin ligands, and 3) the gulose-mannose moiety plays an important role as an environmental factor for the efficient dioxygen reduction and DNA cleavage, although the sugar portion does not contribute significantly to the nucleotide specificity in the DNA strand scission. Certain oligopeptides are able to mimic the metal-binding and dioxygen activation by bleomycin, but not induce the effective DNA cleavage. Probably, the bithiazole DNA interaction site of bleomycin delivers the iron/dioxygen chemistry to particularly the DNA (formula, see text) nucleotide sequences.

Base Sequence↗

Oxygenated iron bleomycin. A short-lived intermediate in the reaction of ferrous bleomycin with O2.

The reaction of Fe(II) . bleomycin with O2 to yield Fe(III) . bleomycin has been resolved into two kinetic events by stopped-flow spectrophotometry. The first event is first order with respect to both bleomycin and O2 and may be regarded as a second order reaction (k = 6.1 x 10(3) M-1s-1 at 2 degrees C). The first product has no EPR spectrum. The optical spectrum resembles those of Fe(II) . bleomycin complexes with CO, NO, and ethyl isocyanide. We propose that the first product is an Fe(II) . bleomycin . O2 complex. The second kinetic event is first order with respect to the first accumulated product (k = 0.11 s-1 at 2 degrees C) and independent of oxygen concentration. The product of this reaction is indistinguishable from Fe(III) . bleomycin by optical and EPR spectroscopy.

Bleomycin↗

Metal coordination environment and dynamics in 113cadmium bleomycin: relationship to zinc bleomycin.

The 13C chemical shifts of Cd- and ZnBlm A2 are almost identical throughout the entire molecule, suggesting that these structures adopt similar conformations. Nuclear magnetic resonance experiments with 113Cd-bleomycin have defined part of the metal-ligand environment of the molecule. Nitrogen atoms from the primary amine, pyrimidine, and imidazole are bound to 113Cd according to 13C spectra showing 113Cd-13C spin-spin couplings. Bound and free forms of the secondary amine nitrogen may be in equilibrium, as suggested by temperature-dependent 13C studies with Cd-bleomycin. In addition, a number of other carbon resonances are in chemical exchange over the temperature range 5-54 degrees C. The temperature dependence of the line widths of carbon atoms of Zn-bleomycin strongly resembles that of Cd-bleomycin. Examination of the 113Cd resonance as a function of temperature also supports the presence of at least two differently coordinated forms of cadmium in the molecule. According to the position of the 113Cd chemical shift, at most four nitrogen atoms are bound to Cd at low temperature. Titrations of 113Cd-bleomycin with chloride or acetate demonstrate that these anions can bind to major and minor forms of the structure and that a minor species exists which does not associate with chloride.

Antibiotics, Antineoplastic↗

Mechanism of reduction of bleomycin-Cu(II) by CO2- and oxidation of bleomycin-Cu(I) by H2O2 in the absence and presence of DNA.

The reduction reaction of bleomycin-Cu(II) by CO2- has been studied by gamma and pulse radiolysis at pH7. The CO2- radical reduces bleomycin-Cu(II) at a rate of (6.7 +/- 0.7) X 10(8) dm3 mol-1 s-1. In the presence of calf thymus DNA the rate of the reduction decreased as the concentration of DNA increased, indicating that the reduction reaction proceeds through free bleomycin-Cu(II). The stoichiometry and the kinetics of the oxidation of bleomycin-Cu(I) by H2O2 in the presence and absence of DNA have been studied. Our observations suggest that the OH. radical is not produced during this reaction and the degradation of the drug occurs in the absence and presence of DNA. We assume that bleomycin-Cu(II) in the presence of a reducing agent and molecular oxygen or H2O2 does not cleave DNA since the oxidizing species, which are formed during the oxidation reaction by H2O2, attack the drug even in the presence of DNA.

Bleomycin↗

Advanced epidemic Kaposi's sarcoma: treatment with bleomycin or combination of doxorubicin, bleomycin, and vincristine.

BACKGROUND: Systemic chemotherapy is a treatment modality in the management of epidemic Kaposi's sarcoma (EKS). We conducted a prospective trial to compare bleomycin as a single agent with a regimen of low-dose doxorubicin, bleomycin, and vincristine (ABV) in patients with advanced EKS. METHODS: Twenty-four homosexual or bisexual patients, between 21 and 40 years old, with positive enzyme-linked immunosorbent assay (ELISA) test for HIV and extensive EKS were included in the study. Half of the patients received bleomycin alone and the other half ABV. RESULTS: A total of seven patients achieved stable disease (SD) and five progressed during bleomycin treatment. A total of four patients achieved partial remission and eight SD during ABV treatment. There was no survival benefit between either arm of treatment. CONCLUSIONS: Bleomycin alone is not a good starting agent for EKS, whereas ABV seems to be a good choice, because it can produce an acceptable palliation of advanced EKS without major toxicity.

Adult↗

Therapy of advanced esophageal cancer with bleomycin, irradiation and combination of bleomycin with irradiation.

Results from treating 51 patients with advanced esophageal cancer are presented. Fifteen patients were treated with Bleomycin, 12 with radiotherapy, and 24 with a combination of bleomycin and radiotherapy. The best results were achieved in the group of patients treated with combined therapy showing 62% objective remissions (15/24) which was statistically significant (P less than 0.001) in comparison to the other groups. In the Bleomycin therapy group, there were 26% objective remissions (4/15), and in the group treated only with radiotherapy 33% (4/12)- The median duration of remission was 9 months in the combined therapy group, 6.3 months in the group treated with radiotherapy, and 2.6 months in the Bleomycin treated group. The authors concluded that the combination of Bleomycin and radiotherapy seems to be a further step in palliative treatment of advanced esophageal cancer.

Adult↗

Covalent binding of bleomycin to concanavalin A and immunoglobulin G enhances the ability of the bleomycin-Fe(II) complex to destroy the erythrocyte membrane.

The antibiotic bleomycin was examined as a possible component of hybrid molecules composed of an address fragment and a generator of reactive oxygen species. The bleomycin-Fe(II) complex was found to destroy the erythrocyte membrane by generating reactive oxygen. The ability of antioxidants to slow down haemolysis points to a free-radical mechanism for this process. The protective effects of catalase and superoxide dismutase indicate that hydrogen peroxide and the superoxide radical formed on autoxidation of the complex are essential for membrane damage. Haemolytic activity is also exhibited by bleomycin-Fe(III) reduced in the NADPH-cytochrome P450 reductase reaction. The covalent binding of bleomycin to such address molecules as concanavalin A and antierythrocyte immunoglobulin G enhances the ability of the bleomycin-Fe(II) complex to destroy the plasma membrane of erythrocytes.

Animals↗

Dibromodulcitol plus bleomycin compared with bleomycin alone in head and neck cancer.

Advanced recurrent squamous cell head and neck cancer patients were prospectively randomized to receive or not receive dibromodulcitol 10 mg/kg PO weekly for 8 consecutive weeks in addition to bleomycin chemotherapy. Patients initially entered in the study received bleomycin 15 mu/m2 three times weekly for 8 weeks. This was later changed to 15 mu/m2 twice weekly for 8 weeks because of unacceptable stomatitis. Most patients had relapsed following surgery and/or radiotherapy, but none had received prior chemotherapy. A2 : 1 randomization in favor of the dibromodulcitol-containing therapy was used. There were 12 partial responses in the 44 evaluable patients receiving the combination (27%), and 4 partial responses in the 18 patients receiving single-agent bleomycin chemotherapy (22%). This difference was not statistically significant. Response durations were also relatively short for both therapies. Within the limitations of this study, we were unable to demonstrate that patient benefit resulted from the addition of dibromodulcitol to bleomycin chemotherapy for this patient population.

Adult↗

Nucleotide sequence cleavages of manganese-bleomycin induced by reductant, hydrogen peroxide and ultraviolet light. Comparison with iron- and cobalt-bleomycins.

The prominent DNA breakages of bleomycin-Mn complex system were induced by reductant, hydrogen peroxide and ultraviolet light, and these three induction systems gave remarkably similar nucleotide sequence cleavage modes. The preferred DNA cleavage sites at guanine-cytosine(5'----3') and guanine-thymine(5'----3') sequences were appreciably comparable to those of the corresponding bleomycin-Fe complex systems, but not identical. In contrast, the bleomycin-Co complex system significantly degraded isolated DNA only by irradiation of ultraviolet light. The present results provide valuable information on the role of transition metals on DNA cleavage reaction of bleomycin.

Base Sequence↗

Design, synthesis, and sequence selective DNA cleavage of functional models of bleomycin. 1. Hybrids incorporating a simple offal-complexing moiety of bleomycin and lexitropsin carriers.

The syntheses of functional models for bleomycin, which are composed of a simple analog of the metal-complexing moiety of bleomycin and oligo-N-methylpyrrole peptide DNA-binding moieties, are described. The extent and the relative rate of their cleavage of DNA in the presence of reductants were determined independently by an ethidium binding assay and by agarose gel electrophoresis experiments. The rate of DNA cleavage increases with the number of N-methylpyrrole units in the carrier moiety. The sequence selectivity of DNA cleavage was demonstrated by polyacrylamide sequencing gel electrophoresis of cleavage reactions on two 5'-32P labeled restriction fragments: a 158 bp GC-rich fragment from pBR322 and a 241 bp AT-rich fragment fragment from SV40. Comparison of the sequence selectivity with that of bleomycin A2 indicates that the poly-N-methylpyrrole moiety directs the hybrid compounds to AT-rich sequences of DNA. High-resolution denaturing gel electrophoresis of DNA cleaved by the model compounds reveals that 3' phosphate is produced exclusively, indicating that the chemistry of DNA cleavage differs from that of bleomycin.

Base Sequence↗

Decrease in pulmonary function during bleomycin-containing combination chemotherapy for testicular cancer: not only a bleomycin effect.

This study was performed to determine the changes in pulmonary function in patients randomised to receive treatment with four cycles of bleomycin, etoposide and cisplatin (BEP) (27 patients) or with four cycles of etoposide and cisplatin (EP) (27 patients) for disseminated non-seminomatous testicular cancer. This enabled us to establish whether effects other than those due to bleomycin determined the detrimental effects of BEP on lung function assessments. Slow inspiratory vital capacity (VC), the transfer factor of the lungs for carbon monoxide (TLCO), the diffusing capacity of the alveolo-capillary membrane (Dm), the pulmonary capillary blood volume (Vc) and the transfer factor of the lungs for carbon monoxide per unit alveolar volume (KCO) were determined before and at 3 week intervals during chemotherapy. Both groups, similar in terms of factors that may influence pulmonary function, showed during therapy a significant decrease in TLCO compared with the pretreatment value. Only at the end of the therapy was a significant difference in TLCO between both groups observed. Dm diminished also significantly in both groups during treatment, but differences between both groups were not seen. VC and Vc decreased in patients receiving BEP but remained constant during treatment with EP. It can be concluded that the Dm, KCO, and the widely used TLCO are not suitable parameters to monitor specifically pulmonary toxicity induced by bleomycin as part of a multidrug regimen. However, VC and Vc appear to be proper lung function assessments which reflect specifically alterations induced by bleomycin.

Adolescent↗

The nucleic acid binding activity of bleomycin hydrolase is involved in bleomycin detoxification.

Yeast bleomycin hydrolase, Gal6p, is a cysteine peptidase that detoxifies the anticancer drug bleomycin. Gal6p is a dual-function protein capable of both nucleic acid binding and peptide cleavage. We now demonstrate that Gal6p exhibits sequence-independent, high-affinity binding to single-stranded DNA, nicked double-stranded DNA, and RNA. A region of the protein that is involved in binding both RNA and DNA substrates is delineated. Immunolocalization reveals that the Gal6 protein is chiefly cytoplasmic and thus may be involved in binding cellular RNAs. Variant Gal6 proteins that fail to bind nucleic acid also exhibit reduced ability to protect cells from bleomycin toxicity, suggesting that the nucleic acid binding activity of Gal6p is important in bleomycin detoxification and may be involved in its normal biological functions.

Antibiotics, Antineoplastic↗

Randomized trial of bleomycin, etoposide, and cisplatin compared with bleomycin, etoposide, and carboplatin in good-prognosis metastatic nonseminomatous germ cell cancer: a Multiinstitutional Medical Research Council/European Organization for Research and Treatment of Cancer Trial.

PURPOSE: This prospective randomized multicenter trial was designed to evaluate the efficacy of carboplatin plus etoposide and bleomycin (CEB) versus cisplatin plus etoposide and bleomycin (BEP) in first-line chemotherapy of patients with good-risk nonseminomatous germ cell tumors. PATIENTS AND METHODS: Between September 1989 and May 1993, a total of 598 patients with good-risk nonseminomatous germ cell tumors were randomized to receive four cycles of either BEP or CEB. In each cycle, the etoposide dose was 120 mg/m2 on days 1, 2, and 3, and the bleomycin dose was 30 U on day 2. BEP patients received cisplatin at 20 mg/m2/d on days 1 to 5 or 50 mg/m2 on days 1 and 2. For CEB patients, the carboplatin dose was calculated from the glomerular filtration rate to achieve a serum concentration x time of 5 mg/mL x minutes. Chemotherapy was recycled at 21-day intervals to a total of four cycles. RESULTS: Of patients assessable for response, 253 of 268 (94.4%) of those allocated to receive BEP achieved a complete response, compared with 227 of 260 (87.3%) allocated to receive CEB (P = .009). There were 30 treatment failures in the 300 patients allocated to BEP and 79 in the 298 allocated to CEB (log-rank chi 2 = 26.9; P < .001), which led to failure-free rates at 1 year of 91% (95% confidence interval [CI], 88% to 94%) and 77% (95% CI, 72% to 82%), respectively. There were 10 deaths in patients allocated to BEP and 27 in patients allocated to CEB (log-rank chi 2 = 8.77; P = .003), which led to 3-year survival rates of 97% (95% CI, 95% to 99%) and 90% (95% CI, 86% to 94%), respectively. CONCLUSION: With these drug doses and schedules, combination chemotherapy based on carboplatin was inferior to that based on cisplatin. This BEP regimen that contains moderate doses of etoposide and bleomycin is effective in the treatment of patients with good-prognosis metastatic nonseminoma.

Adult↗

[Effect of continuous bleomycin treatment and of oil-suspended bleomycin on experimental tumor growth (author's transl)].

Effects of continuous administration of bleomycin solution and of intralesional injection of sesame oil-suspended bleomycin on tumor growth were studied. Experimental animal tumors were 3 rd generation isotransplants of a spontaneous C3H mouse mammary carcinoma. Bleomycin treatments were started when transplanted tumors reached 8 mm in diameter and the measurement of tumor volume was followed. Dose administered was fixed as 100 mg/kg in all the groups. Bleomycin solution was given intralesionally in a single or 4 daily doses, or intraperitoneally by continuous infusion. The latter method inhibited tumor growth most effectively, while the single injection was the last effective. Intralesional injection of oil-suspended exhibited similar effectiveness as the continuous infusion, and it was independent of the number of fractions. These results were interpreted by the several features in the response of mammalian cells to the antibiotic.

Animals↗