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Biomedical subjects

T Tsuruo

Publications and source records attributed to T Tsuruo.

At least 343 records · Page 19Linked to original sources
PubMed1991

Circumvention of multidrug resistance by a newly synthesized quinoline derivative, MS-073.

Newly synthesized quinoline derivatives were investigated for their efficacy to reverse multidrug resistance (MDR). In this study, one of the most effective quinoline derivatives, MS-073, was compared with verapamil with regard to its ability to overcome MDR in vitro and in vivo. MS-073 at 0.1 microM almost completely reversed in vitro resistance to vincristine (VCR) in VCR-resistant P388 cells. The compound also reversed in vitro VCR, adriamycin (ADM), etoposide, and actinomycin D resistance in ADM-resistant human myelogenous leukemia K562 (K562/ADM) cells, ADM-resistant human ovarian carcinoma A2780 cells, and colchicine-resistant human KB cells. MS-073 administered i.p. daily for 5 days with VCR enhanced the chemotherapeutic effect of VCR in VCR-resistant P388-bearing mice. Increases in life span of 19-50% were obtained by the combination of 100 micrograms/kg of VCR with 3-100 mg/kg of MS-073, as compared to the control. The ability of MS-073 to reverse MDR was remarkably higher, especially at low MS-073 doses, than that of verapamil, both in vitro and in vivo. MS-073 enhanced accumulation of [3H]VCR in K562/ADM cells. Photolabeling of P-glycoprotein with 200 nM [3H]azidopine in K562/ADM plasma membranes was completely inhibited by 10 microM MS-073, indicating that MS-073 reverses MDR by competitively inhibiting drug binding to P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Magnetic-affinity cell sorting of human multidrug-resistant cells.

We have developed a method for isolating multidrug-resistant cells from a heterogeneous cell population using the magnetic-affinity cell-sorting system. Human KB carcinoma cell lines expressing different amounts of P-glycoprotein have been selected by use of the monoclonal antibody MRK-16 coupled to magnetic particles. This specific, rapid, and sensitive method allows the selection of viable and clonable drug-resistant cells from various drug-resistant human and murine cell populations. This method may prove useful in isolating drug-resistant cells from tumors with heterogeneous P-glycoprotein expression for further analysis.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Suppression of experimental lung colonization of a metastatic variant of murine colon adenocarcinoma 26 by a monoclonal antibody 8F11 inhibiting tumor cell-induced platelet aggregation.

We have previously established and characterized two monoclonal antibodies, 8F11 and 20A11, that recognize an Mr 44,000 membrane glycoprotein of metastatic murine colon 26 cells. Both monoclonal antibodies inhibit platelet aggregation induced by the tumor cells in vitro. In this report, the inhibitory effect of 8F11 on lung colonization of i.v.-inoculated tumor cells was examined. The i.v. administration of 8F11 suppressed lung colonization of NL-17, a highly metastatic variant of colon 26. Inhibition of NL-17 lung colonization by 8F11 was dose dependent with a maximum of 80% inhibition at a dose of 800 micrograms 8F11/mouse. 8F11 did not inhibit metastases at doses lower than 100 micrograms/mouse. Inhibition of pulmonary metastases by 8F11 was greatest when the antibody was administered 2 h before tumor inoculation. The effect was diminished when the antibody was given 2 h after tumor inoculation. The pulmonary retention of i.v.-inoculated radiolabeled NL-17 cells was decreased by 8F11. F(ab')2 fragments of 8F11 also effectively inhibited lung colonization by NL-17 cells, suggesting that mechanisms unrelated to immune-mediated destruction are involved. These results indicate that the monoclonal antibody 8F11 suppresses the lung colonization of NL-17 cells by interfering with the initial arrest of tumor cells in the lung vasculature through the inhibition of tumor cell-platelet interaction.

Adenocarcinoma↗
PubMed1991

Cellular pharmacology of MX2, a new morpholino anthracycline, in human pleiotropic drug-resistant cells.

We previously reported that MX2, a new morpholino anthracycline, showed marked effects on pleiotropic drug-resistant sublines of murine P388 leukemia in vivo as well as in vitro. In this study we examine the in vitro cytotoxicity against pleiotropic drug-resistant sublines of human tumor cell lines. MX2 was effective against multidrug-resistant sublines of four human tumor cell lines; these cells, having a 4.8- to 200-fold cross-resistance to Adriamycin (ADM) showed only a 0.7- to 2.3-fold resistance to MX2 compared with the sensitive cells. To elucidate the mechanism by which MX2 overcomes multidrug resistance, the intracellular pharmacology of MX2 in human myelogenous leukemia K562 and its ADM-resistant subline (K562/ADM) was examined. Both K562 and K562/ADM cells accumulated MX2 more easily than ADM, and the intracellular accumulation of MX2 attained a steady state in both cell lines within 30 min of incubation at 37 degrees C. The amount of MX2 that accumulated in K562/ADM at a steady state was only 1.3 times lower than that in K562. However, ADM was accumulated slowly in both cell lines compared with MX2, and the intercellular concentration reached a steady state in K562/ADM after 90 min of incubation and in K562 after more than 120 min. K562/ADM cells accumulated a 3.3-fold lower concentration of ADM than K562 after 120 min of exposure. The steady-state concentration of ADM in K562/ADM was 8.3 times lower than that of MX2. In addition, greater than 70% of MX2 was retained in both cell lines after 150 min of incubation in the absence of this drug. Verapamil, a calcium antagonist, hardly augmented the cytotoxicity of MX2 against K562/ADM, and no distinct effect of this drug on both the time course and the maximal level of accumulation of MX2 was observed. Interestingly, MX2 effectively inhibited ATP/Mg2(+)-dependent [3H]vincristine binding to K562/ADM membrane preparations, indicating that MX2 could be transported outside the cell by an active efflux pump. The high intracellular accumulation and retention of MX2 in K562/ADM through the rapid influx of the drug into the cells may be one of the reasons why MX2 circumvents pleiotropic drug resistance.

Antibiotics, Antineoplastic↗
PubMed1991

Detection of multidrug-resistant protein, P-glycoprotein in childhood leukaemia and lymphoma.

Flow cytometric detection of surface P-glycoprotein, a multidrug-resistant gene product, with a monoclonal antibody, MRK 16, was performed on cells obtained from 18 children with leukaemia and lymphoma. Of 18 patients examined, 1 with malignant lymphoma at relapse showed a significant increase in P-glycoprotein-positive cells and a strong resistance to chemotherapy. Overexpression of P-glycoprotein in a case with B-cell type malignant lymphoma was confirmed by immuno-precipitation and Northern hybridization analysis. The present study suggests that an increased expression of surface P-glycoprotein might be involved in multidrug resistance at least in a certain case of childhood leukaemia and lymphoma.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Human ovarian cancer cell lines resistant to cisplatin, doxorubicin, and L-phenylalanine mustard are sensitive to delta 7-prostaglandin A1 and delta 12-prostaglandin J2.

The antitumor activity of delta 7-prostaglandin A1 (delta 7-PGA1) or delta 12-prostaglandin J2 (delta 12-PGJ2) on human ovarian cancer cell lines resistant to cisplatin (CDDP), doxorubicin (ADR), and L-phenylalanine mustard (l-PAM) was studied in vitro. A2780AD, A2780 (parent cells of A2780AD), 2008DDP, and 2008 cells (parent cells of 2008DDP) were used. The antitumor activities of the drugs were defined with 50% inhibitory concentration (IC50) estimated from growth inhibition curves, which were obtained by an indirect colorimetric method. Drug-resistance ratios obtained from IC50 values, by comparing A2780AD and A2780 cells, were 62.5 for ADR, 4.6 for CDDP, 4.9 for l-PAM, 1.5 for delta 7-PGA1, and 1.8 for delta 12-PGJ2. Those obtained by comparing 2008DDP and 2008 cells were 1.1 for ADR, 16.0 for CDDP, 2.9 for l-PAM, 2.3 for delta 7-PGA1, and 3.2 for delta 12-PGJ2. Thus some human ovarian cancer cells resistant to ADR, CDDP, and l-PAM remain sensitive to antitumor PGs.

Antineoplastic Agents↗
PubMed1991

Absolute structure-cytotoxic activity relationships of steganacin congeners and analogues.

The cytotoxic activities of optically pure and racemic steganacin congeners and analogues against KB cells in culture and the inhibitor activity of cilia regeneration in Tetrahymena were studied with regard to absolute and relative configurations. The stereochemical requirements of dibenzocyclooctadiene lignan lactones for activity were clarified.

4-Butyrolactone↗
PubMed1991

Identification and characterization of three DNA-binding proteins on the promoter of the human MDR1 gene in drug-sensitive and -resistant cells.

In multidrug-resistant cell lines (K562/ADM), MDR1 was amplified and transcriptionally activated. But the mechanism of MDR1 expression is unknown in K562/ADM cells. A 131 bp DNA fragment upstream from the major cap site of MDR1 contained CAAT-like and GC-box-like motifs and showed promoter activity in a CAT expression assay, resulting in a 3.5-fold enhancement of MDR1 promoter activity in K562/ADM as compared with that in K562 cells. In the CAT assay using deletion mutants we found that sequences containing the CAAT-like motif and the GC-box-like motif were required for MDR1 proximal promoter activity. To understand the details of MDR1 transcription in K562/ADM cells we analyzed the interaction between the proximal promoter and DNA-binding protein(s). We have identified three DNA-binding proteins on the MDR1 promoter from K562/ADM and parental K562 cells. The first binding protein to the MDR1 promoter was NF-R1, which recognized the sequences containing the CAAT-like motif and the GC-box-like motif as revealed by using a gel mobility shift assay. The second protein was NF-R2, which bound to the sequence containing the CAAT-like motif. The third protein, which bound to the sequence containing the GC-box-like motif was designated NF-R3. NF-R2 and NF-R3 in the resistant cells formed different bands in the gel mobility shift assays as compared with those in the sensitive cells, respectively. The observed difference might be related to the transcriptional activation of MDR1 in K562/ADM cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Characterization of an etoposide-resistant human K562 cell line, K/eto.

An etoposide-resistant K562 cell line (K/eto) was obtained by stepwise exposure, in culture, to increasing concentrations of etoposide, without the use of mutagens. This cell line was resistant to etoposide, and slightly resistant to adriamycin, but sensitive to anti-cancer drugs such as camptothecin, vincristine, actinomycin D and so on. P-Glycoprotein, the mdr1 gene product, was not detected in this cell line, as assessed by immunocytochemistry, immunoprecipitation and flow cytometry. Overexpression of mdr1 mRNA was also not found. Interestingly, expression of 85 kD protein recognized by MRK 20 monoclonal antibody was noted. The level of DNA topoisomerase II protein, detected by antibody staining, decreased concomitantly with a general decrease in DNA topoisomerase II unknotting activity, while DNA topoisomerase I activity was not affected. Cellular accumulation of [3H]etoposide was reduced by 75% in the resistant line compared with parental K562. Karyotype analysis showed that the number of chromosomes in K/eto was 55 and neither a homogeneous staining region nor double-minute chromosomes were detected. These results indicate that this resistance is not due to an altered interaction between the drug and cellular transport machinery, i.e. MDR1, associated with the "classic" multiple drug resistance phenotype, but rather is due to the existence of other mechanism(s) of resistance, decreased transport of the drug and decreased target enzyme, DNA topoisomerase II.

Antibodies, Monoclonal↗
PubMed1991

Immunohistochemical detection of the multidrug transport protein P170 in human normal tissues and malignant lymphomas.

Two monoclonal antibodies, MRK16 and C219, both directed at the 170 kDa P-glycoprotein multidrug resistance agent, were applied to frozen sections or cytospin preparations from normal human tissues and 60 non-Hodgkin's malignant lymphomas. Adrenal gland, kidney, liver and pancreas were always stained by the reagents, albeit with slightly different patterns. Brain capillaries as well as macrophages and some elements of the bone marrow, peripheral blood, ovarian stroma and colonic, gastric and jejunal mucosa were positive in all examined preparations. There were differences in the staining patterns with the two antibodies. Among the 60 non-Hodgkin's lymphomas, 25 contained a number of positive cells, which ranged from 2% to 100%. No correlation was seen between the expression of P170 and histological type, stage, clinical symptoms or growth fraction. A close relationship was shown between the presence of P170 positive elements and the clinical course of the disease (P less than 0.001).

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Detection of P-glycoprotein in human urogenital carcinomas and its relationship to epidermal growth factor receptor expression.

P-glycoprotein and epidermal growth factor (EGF) receptor expression were surveyed immunohistochemically in the tissue of urogenital carcinomas including 12 renal cell carcinomas, 9 bladder transitional cell carcinomas, 2 prostate adenocarcinomas and 1 penile squamous cell carcinoma. Three bladder carcinomas and the penile carcinoma were following initial chemotherapy at the time of relapse. P-glycoprotein expression was detected in 3 of 12 renal cell carcinomas and in all recurrent carcinomas. EGF receptor was not detected in any of the specimens.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Elevated expression of P-glycoprotein in kidney and urinary bladder cancers.

A monoclonal antibody, MRK16, recognizing specifically an epitope of P-glycoprotein (P-GP), a highly active efflux transporter of chemotherapeutic agents, was used to determine the degree of expression of P-GP in the normal human kidney and urinary bladder, and in kidney and urinary bladder cancers. P-glycoprotein was localized in the microvilli of the epithelial cells of the proximal renal tubules by immunoelectron microscopy, and detected immunohistochemically in 6 of 20 untreated kidney cancers and 11 of 31 untreated urinary bladder cancers. Some of the cancerous tissues were further examined with regard to P-GP expression by immunoprecipitation. In urinary bladder cancers, the degree of P-GP expression seemed to be somewhat correlated with tumor grading. These results indicate that our method to detect the degree of expression of P-GP by MRK16 may be applicable for the diagnosis of clinical multidrug resistant urinary cancers.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Transfection with protein kinase C alpha confers increased multidrug resistance to MCF-7 cells expressing P-glycoprotein.

Cross-resistance to anticancer drugs, termed multidrug resistance (mdr), has been functionally associated with the expression of a plasma membrane energy-dependent efflux pump, termed P-glycoprotein, the product of the mdr1 gene. When MCF-7 breast carcinoma cells were transfected with the human mdr1 gene (BC-19 cells), they expressed levels of P-glycoprotein equivalent to those of cells selected for resistance to doxorubicin (MCF-7/ADR) but exhibited 10- to 50-fold less resistance to doxorubicin and vinblastine. We have now demonstrated that when BC-19 cells were stably transfected with protein kinase C alpha (PKC alpha), resistance to doxorubicin and vinblastine was increased; wild-type MCF-7 cells transfected with PKC alpha did not exhibit any change in drug resistance. Increased resistance in PKC alpha-transfected BC-19 cells was associated with enhanced PKC activity and phosphorylation of P-glycoprotein and decreased drug accumulation. The PKC activator, phorbol dibutyrate, further increased resistance to doxorubicin and stimulated P-glycoprotein phosphorylation. These results demonstrate that transfection of P-glycoprotein-expressing cells with PKC resulted in increased mdr and that PKC may have served as an important modulator of this process.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

P-glycoprotein expression and in vitro reversion of doxorubicin resistance by verapamil in clinical specimens from acute leukaemia and myeloma.

The expression of the P-glycoprotein which is associated with the development of multidrug resistance in various cell lines was investigated in 87 fresh acute leukaemia and multiple myeloma samples using the specific mouse monoclonal antibody MRK16 in an indirect immunofluorescence assay. Considering a 10% positive cell cut-off value, a heterogeneous expression of P-glycoprotein was observed in 5/22 (22.7%) de novo acute leukaemias, 7/22 (31.8%) relapse or secondary acute leukaemias, 14/27 (51.8%) acute transformation of myeloproliferative or myelodysplastic syndromes and 5/16 (31.2%) multiple myelomas. This expression was not associated with specific cytogenetic abnormalities, especially alterations of chromosome 7q. Verapamil, a calcium channel blocker, has been demonstrated to circumvent the multidrug resistance in cell lines, possibly by interfering with P-glycoprotein function. Using the microculture tetrazolium assay, verapamil was demonstrated to increase the sensitivity of fresh leukaemic or myeloma cells to doxorubicin in 19/43 (43.1%) samples. The doxorubicin IC50 level and the capacity of verapamil to increase the sensitivity of blast cells to doxorubicin in vitro did not correlate with the expression of P-glycoprotein. We conclude that high non-cytotoxic concentrations of verapamil were able to increase the in vitro doxorubicin sensitivity of fresh acute leukaemia and myeloma cells without detectable expression of the P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Increased drug accumulation ex vivo with cyclosporin in chronic lymphatic leukemia and its relationship to epitope masking of P-glycoprotein.

The ability of cyclosporin to modify drug accumulation in vitro, measured by the cellular accumulation of daunorubicin, was examined. In 42 patients with chronic lymphatic leukaemia this correlates well with the levels of P-glycoprotein (Pgp) measured by immunofluorescent labelling of Pgp after treatment of the cells with neuraminidase to unmask the epitope recognized by the monoclonal antibody MRK 16. It is shown that flow cytometric analysis using MRK 16 to detect Pgp expression levels together with drug accumulation studies can rapidly assess the multidrug-resistant phenotype of patients' cells, and enable selection of those suitable for therapy with agents known to circumvent mdr-1 mediated drug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1990

Staurosporine, a potent inhibitor of C-kinase, enhances drug accumulation in multidrug-resistant cells.

Staurosporine, a potent inhibitor of C-kinase, enhances accumulation of vincristine (VCR) in multidrug-resistant cells. We investigated this enhancement by two methods: (I) ATP-dependent VCR binding system; (II) azidopine photolabeling system. The ATP-dependent VCR binding to the resistant cell membrane was inhibited more efficiently by staurosporine than by verapamil. Staurosporine also inhibited the azidopine photolabeling of P-glycoprotein. These results indicate that staurosporine, an inhibitor of C-kinase, might directly bind to P-glycoprotein as well as antitumor agents and Ca2+ channel blockers. These findings also indicate that C-kinase might be involved in the function of P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗