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Acta Medica Okayama Jun 2002When the development of chemotherapeutic agents reaches the clinical trial stage, it is necessary to perform drug sensitivity tests quickly in order to select the most... (Comparative Study)
Comparative Study
When the development of chemotherapeutic agents reaches the clinical trial stage, it is necessary to perform drug sensitivity tests quickly in order to select the most promising agents for the treatment of cancer. In order to assess the possibility of using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay as a substitute for the human tumor clonogenic assay (HTCA), we evaluated the correlation between the results obtained by these 2 assays in 5 human lung cancer cell lines. The correlation coefficient between the results of the HTCA and the MTT assay was 0.673, indicating a relatively good correlation. The correlation was most prominent in platinum analogues (r = 0.939) and good in anthracyclines/anthracenedione (r = 0.611). However, no significant correlation was observed in vinca alkaloids, etoposide, irinotecan, SN-38 (an active metabolite of irinotecan), and rhizoxin. The results of the MTT assay showed a high degree of correlation with those of the HTCA in predicting the sensitivity of cancer cell lines to platinum analogues, and anthracyclines/anthracenedione. These results suggest that the MTT assay may be more convenient and quickly performed than the HTCA and can replace HTCA in evaluating the effects of anticancer agents, especially the platinum analogues and anthracyclines/anthracenedione.
Topics: Antineoplastic Agents; Coloring Agents; Drug Screening Assays, Antitumor; Humans; Inhibitory Concentration 50; Lung Neoplasms; Tetrazolium Salts; Thiazoles; Tumor Cells, Cultured; Tumor Stem Cell Assay
PubMed: 12108583
DOI: 10.18926/AMO/31714 -
The Journal of Eukaryotic Microbiology 2001The genome of Trypanosoma brucei contains about 120 chromosomes, which do not visibly condense during mitosis. We have analyzed the organization and segregation of these...
The genome of Trypanosoma brucei contains about 120 chromosomes, which do not visibly condense during mitosis. We have analyzed the organization and segregation of these chromosomes by in situ hybridization using fluorescent telomere probes. At the onset of mitosis, telomeres migrate from their nuclear peripheral location and congregate into a central zone. This dense group of telomeres then splits into two entities that migrate to opposite nuclear poles. Segregation continues until the double-sized nucleus divides and, before cytokinesis occurs, the telomeres reorganize into the discrete foci observed at interphase. During migration, the telomeres are located at the free end of the mitotic spindle. Treatment with the microtubule polymerization inhibitor rhizoxin prevents telomere clustering and chromosomal segregation. In the insect-specific procyclic form as well as in the non-dividing bloodstream stumpy form, telomeres tend to cluster close to the nuclear periphery at interphase. In contrast, in the proliferative bloodstream slender form the telomeres preferentially locate in the central zone of the nucleus. Thus, telomeres are closer to the nuclear periphery during those life cycle stages where the telomeric expression sites for the variant surface glycoprotein are all inactive, suggesting that transcriptional inactivation of these sites is related to their subnuclear localization.
Topics: Animals; Cell Cycle; Cell Division; Cell Nucleus; Chromosome Segregation; Interphase; Lactones; Life Cycle Stages; Macrolides; Microtubules; Mitosis; Spindle Apparatus; Telomere; Transcription, Genetic; Trypanosoma brucei brucei
PubMed: 12095111
DOI: 10.1111/j.1550-7408.2001.tb00306.x -
The Journal of Organic Chemistry Oct 1998A triply convergent synthetic approach which culminates in the enantioselective syntheses of the C(1)-C(9) and C(12)-C(26) subunits of the macrolide antitumor agent...
A triply convergent synthetic approach which culminates in the enantioselective syntheses of the C(1)-C(9) and C(12)-C(26) subunits of the macrolide antitumor agent rhizoxin is described. The central C(12)-C(20) subunit 4 has been prepared efficiently via diastereoselective enzymatic acetate hydrolysis of 15 with porcine pancreatic lipase, a chelation-controlled Ireland-Claisen rearrangement (10 --> 12) combined with kinetic bromolactonization (12 --> 14), and Mitsunobu inversion (23 --> 26) to introduce the three contiguous C(15)-C(17) stereocenters. Formation of the C(18)-C(19) trisubstituted (E)-olefin was achieved by a stereoselective Horner-Wadsworth-Emmons reaction. The central segment 4 and the oxazole chromophore side chain 3 were coupled using another highly stereoselective Horner-Wadsworth-Emmons reaction. Two different lactone subunits [C(1)-C(9) segment 5 and C(3)-C(10) segment 47] were also prepared, employing a thermodynamically controlled diastereotopic group differentiation tactic for establishing the C(5) stereochemistry.
PubMed: 11672317
DOI: 10.1021/jo980754k -
Angewandte Chemie (International Ed. in... Jan 2001
PubMed: 11169722
DOI: No ID Found -
Angewandte Chemie (International Ed. in... Jan 2001
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Cancer Research Sep 2000We describe a cell-based assay for antimitotic compounds that is suitable for drug discovery and for quantitative determination of antimitotic activity. In the assay,...
We describe a cell-based assay for antimitotic compounds that is suitable for drug discovery and for quantitative determination of antimitotic activity. In the assay, cells arrested in mitosis as a result of exposure to antimitotic agents in pure form or in crude natural extracts are detected by ELISA using the monoclonal antibody TG-3. The assay was used to screen >24,000 extracts of marine microorganisms and invertebrates and terrestrial plants and to guide the purification of active compounds from 5 of 119 positive extracts. A new rhizoxin analogue was found in a Pseudomonas species, six new eleutherobin analogues were identified from the octocoral Erythropodium caribaeorum, and two paclitaxel analogues were found in the stem bark of the tree Ilex macrophylla. The assay was also used for quantitative comparison of the antimitotic activity of different analogues. It revealed the importance of the C-11 to C-13 segment of the diterpene core of eleutherobin for its antimitotic activity. The identification of antimitotic compounds in very low abundance and their high (0.5%) occurrence in natural extracts indicates that drug discovery efforts using this cell-based assay may lead to the identification of structurally novel antimitotic agents.
Topics: Alkaloids; Animals; Antibiotics, Antineoplastic; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Breast Neoplasms; Diterpenes; Drug Screening Assays, Antitumor; Enzyme-Linked Immunosorbent Assay; Humans; Invertebrates; Lactones; Macrolides; Marine Biology; Paclitaxel; Plant Extracts; Plants, Medicinal; Pseudomonas; Structure-Activity Relationship; Tissue Extracts; Tumor Cells, Cultured
PubMed: 11016628
DOI: No ID Found -
Cancer Chemotherapy and Pharmacology 2000In previous phase I reports of short bolus infusion of rhizoxin, problems in assay sensitivity prevented the description of pharmacokinetic-pharmacodynamic... (Clinical Trial)
Clinical Trial
In previous phase I reports of short bolus infusion of rhizoxin, problems in assay sensitivity prevented the description of pharmacokinetic-pharmacodynamic relationships, and a pharmacologically guided approach to dose escalation was deemed not feasible. In this report, we describe a mathematical model, which explains the schedule-dependent interpatient pharmacodynamic variability of rhizoxin administered on a continuous infusion schedule. Using patient demographic and toxicity data from 45 patients treated in a phase I dose and duration escalation study of rhizoxin, we sought to model the nadir neutrophil count. We hypothesized that a surrogate derived variable based on dose and duration would reflect a pharmacokinetic parameter that would be a significant covariate. Multiple linear regression analysis was carried out to determine the other significant covariates. Dose/m2 x Log(DUR/ALB) was significantly correlated with the LogANCnadir (Log10 neutrophil nadir; r = 0.56, P < 0.001). Other significant covariates included baseline performance status (PS), baseline serum bilirubin (BIL), and Log10 baseline neutrophil count (LogANCbaseline). Model bias and precision were assessed using the mean prediction error (MPE) and the root mean square error (RMSE) of the ANCnadir, respectively. We constructed 1-4 covariate models. The variability of ANCnadir was modeled with good precision and accuracy with a 4-covariate model (MPE and RMSE 0.113 +/- 0.182 x 10(3) cells/microl and 1.22 x 10(3) cells/microl, respectively). This model should be validated and improved on with further clinical data. We believe that such pharmacodynamic modeling should be explored further to determine its performance and clinical relevance compared with modeling using pharmacokinetic parameters.
Topics: Adult; Aged; Aged, 80 and over; Antibiotics, Antineoplastic; Drug Administration Schedule; Female; Humans; Lactones; Macrolides; Male; Middle Aged; Models, Biological
PubMed: 10854137
DOI: 10.1007/s002800051024 -
Annals of Oncology : Official Journal... Mar 2000Rhizoxin (NSC 332598) is a novel macrolide antitumor antibiotic that inhibits microtubule assembly and also depolymerizes preformed microtubules. In preclinical... (Clinical Trial)
Clinical Trial
BACKGROUND
Rhizoxin (NSC 332598) is a novel macrolide antitumor antibiotic that inhibits microtubule assembly and also depolymerizes preformed microtubules. In preclinical evaluations, rhizoxin demonstrated broad antitumor activity in vitro and in vivo including both vincristine- and vindesine-resistant human lung cancers. Prolonged exposure schedules in xenograft models demonstrated optimal efficacy indicating schedule-dependent antitumor activity. The early phase I and II evaluations a five-minute bolus infusion schedule was studied, however, only modest anti-tumor activity was noted, possibly due to rapid systemic clearance. To overcome these limitations and to exploit the potential for schedule-dependent behavior of rhizoxin, the feasibility of administering rhizoxin as a 72-hour continuous intravenous (i.v.) infusion was evaluated.
PATIENTS AND METHODS
Patients with advanced solid malignancies were entered into this phase I study, in which both the infusion duration and dose of rhizoxin were increased. The starting dose was 0.2 mg/m2 over 12 hours administered every 3 weeks. In each successive dose level, the dose and infusion duration were incrementally increased in a stepwise fashion. Once a 72-hour i.v. infusion duration was reached, rhizoxin dose-escalations alone continued until a maximum tolerated dose (MTD) was determined.
RESULTS
Nineteen patients were entered into the study. Rhizoxin was administered at doses ranging from 0.2 mg/m2 i.v. over 12 hours to 2.4 mg/m2 i.v. over 72 hours every 3 weeks. The principal dose-limiting toxicities (DLT) were severe neutropenia and mucositis, and the incidence of DLT was unacceptably high at rhizoxin doses above 1.2 mg/m2, which was determined to be the MTD and dose recommended for phase II studies. At these dose levels, rhizoxin could not be detected in the plasma by a previously validated and sensitive high-performance liquid chromatography assay with a lower limit of detection of 1 ng/ml. No antitumor responses were observed.
CONCLUSIONS
Rhizoxin can be safely administered using a 72-hour i.v. infusion schedule. The toxicity profile is similar to that observed previously using brief infusion schedules. Using this protracted i.v. infusion schedule the maximum tolerated dose is 1.2 mg/m2/72 hours.
Topics: Adult; Aged; Antibiotics, Antineoplastic; Humans; In Vitro Techniques; Lactones; Macrolides; Middle Aged; Neoplasms; Neutropenia
PubMed: 10811501
DOI: 10.1023/a:1008398725442 -
Anticancer Research 1999The improvement of treatment outcome of small-cell lung cancer (SCLC), and search for new effective drugs and to overcome drug-resistance are essential.
BACKGROUND
The improvement of treatment outcome of small-cell lung cancer (SCLC), and search for new effective drugs and to overcome drug-resistance are essential.
MATERIALS AND METHODS
We evaluated the cytotoxicity of antimicrotubule agents to seven human SCLC cell lines consisting of one cell line (SBC-3) established from a previously untreated patient as a representative of drug-sensitive cell line, three cell lines (SBC-2, SBC-4, and -7) derived from treated patients as representatives of intrinsic drug-resistance cell lines, and three drug-resistant sublines (SBC-3/ADM, SBC-3/ETP, and SBC-3/CDDP) selected by continuous exposure of the SBC-3 cell line to increasing concentrations of doxorubicin, etoposide, or cisplatin as representatives of acquired drug-resistant cell lines.
RESULTS
IC50 values for SBC-2, -3, -4, and -7 cells of antimicrotubule agents were markedly lower than those of doxorubicin, etoposide, and cisplatin. Both SBC-3/ADM and SBC-3/ETP subline were highly resistant to paclitaxel, docetaxel, vinorelbine, vincristine, vindesine, and vinblastine. However, an SBC-3/ADM subline was not fully cross-resistant to rhizoxin, and an SBC-3/ETP subline was as sensitive to rhizoxin as an SBC-3 cell line. A cisplatin-resistant subline, SBC-3/CDDP, showed no cross-resistance to the antimicrotubule agents.
CONCLUSION
These results suggest that antimicrotubule agents are useful for SCLC, and rhizoxin may be particularly effective in the salvage treatment of refractory or relapsed patients.
Topics: Antibiotics, Antineoplastic; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Carcinoma, Small Cell; Cisplatin; Docetaxel; Doxorubicin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Etoposide; Humans; Inhibitory Concentration 50; Lactones; Lung Neoplasms; Macrolides; Microtubules; Paclitaxel; Taxoids; Tumor Cells, Cultured
PubMed: 10628341
DOI: No ID Found -
Journal of Cell Science Dec 1999Trypanosoma brucei has a single nucleus and a single kinetoplast (the mitochondrial genome). Each of these organelles has a distinct S phase, which is followed by a...
Trypanosoma brucei has a single nucleus and a single kinetoplast (the mitochondrial genome). Each of these organelles has a distinct S phase, which is followed by a segregation period, prior to cell division. The segregation of the two genomes takes place in a specific temporal order by interaction with microtubule-based structures, the spindle for nuclear DNA and the flagellum basal bodies for the kinetoplast DNA. We used rhizoxin, the anti-microtubule agent and polymerisation inhibitor, or the nuclear DNA synthesis inhibitor aphidicolin, to interfere with cell cycle events in order to study how such events are co-ordinated. We show that T. brucei cytokinesis is not dependent upon either mitosis or nuclear DNA synthesis, suggesting that there are novel cell cycle checkpoints in this organism. Moreover, use of monoclonal antibodies to reveal cytoplasmic events such as basal body duplication shows that some aphidicolin treated cells appear to be in G(1) phase (1K1N) but have activated some cytoplasmic events characteristic of G(2) phase (basal body segregation). We discuss a possible dominant role in trypanosomes for kinetoplast/basal body segregation in control of later cell cycle events such as cytokinesis
Topics: Animals; Aphidicolin; Cell Cycle; Cell Nucleus; DNA, Kinetoplast; Lactones; Macrolides; Mitochondria; Mitosis; Trypanosoma brucei brucei
PubMed: 10574712
DOI: 10.1242/jcs.112.24.4641