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T Tsuruo

Publications and source records attributed to T Tsuruo.

At least 451 records · Page 25Linked to original sources
PubMed1987

Immunocytochemical localization of P170 at the plasma membrane of multidrug-resistant human cells.

P170 (P-glycoprotein) is a membrane protein found in high levels in multidrug-resistant cultured cell lines. We have localized this protein using monoclonal antibody MRK16 by immunofluorescence and electron microscopy in the multidrug-resistant human carcinoma cell line KB-C4. The P170 determinant recognized by antibody MRK16 was found on drug-resistant KB-C4 cells, but not on parental drug-sensitive KB-3-1 cells. The determinant was present on the external surface of the plasma membrane and on the luminal side of Golgi stack membranes. P170 was excluded from coated pits at the plasma membrane and absent from endocytic vesicles and lysosomes. This determinant was detected only in small amounts in the endoplasmic reticulum. The high protein concentration of P170 in the plasma membrane is consistent with a role of this protein as a drug efflux pump at the cell surface.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1987

A novel antitumor cyclic hexapeptide (RA-700) obtained from Rubiae radix.

The antitumor activity of a newly obtained cyclic hexapeptide, RA-700, from Rubiae Radix was studied using several murine experimental tumor systems. In P388 leukemia (inoculated intraperitoneally (i.p.), administered i.p.: i.p.-i.p.) the maximal increase in life span (ILSmax) resulting from an administration of RA-700 (4 mg/kg/d for 9 d) was 134% and the therapeutic ratio was 400. These values indicate that RA-700 has higher anti-tumor activity and broader active dose range than that of mitomycin C (MMC, 1 mg/kg/d for 9 d) which was used as a positive control. In the study of the treatment schedules on P388, RA-700 had the highest activity by consecutive injections. In MOPC-104E mouse plasmacytoma system (i.p.-i.p.), ILSmax of RA-700 (2.5 mg/kg/d for 9 d) was 84%. In a solid tumor, colon adenocarcinoma 38 (subcutaneously (s.c.)-intravenously (i.v.], RA-700 (4 mg/kg/d for 11 d) showed complete cures (8/8) compared to MMC (0.5 mg/kg/d for 11 d) which showed one cure out of 8 animals. In the study of a model of the inhibition of lymph node metastasis using P388 leukemia, the administration of RA-700 at more than 2.5 mg/kg/d i.v. for 7 d resulted in the survival of all animals (5/5) for over 60 d. In the amputation system of the same metastasis model at a dose of 4 mg/kg/d i.v. for 7 d, 3 animals out of 5 survived over 60 d.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Detection of multidrug resistance markers, P-glycoprotein and mdr1 mRNA, in human leukemia cells.

We have examined the expression of P-glycoprotein in clinical leukemic cell samples by using a monoclonal antibody (MRK16) against P-glycoprotein. We found that leukemia cells isolated from 3 out of 6 patients with blast crisis of chronic myelogenous leukemia were reactive to MRK16. These 3 cell lines expressed high levels of mdr1 mRNA, which codes for P-glycoprotein. The present result indicates that the clinically refractory state of the tumor may be predicted in part by determining P-glycoprotein expression using the monoclonal antibody against P-glycoprotein, and the mdr1 probe.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1987

[Antitumor drug screening at the National Cancer Institute, U.S.A].

The development of suitable screening systems is one of the most important determinants for the successful discovery of new anti-tumor drugs. The National Cancer Institute, U.S.A. has been playing a major role in the discovery and development of new agents by using various animal tumor models since 1955. In this article, the historical overview of this effort, and the difficulties and problems of this approach was reviewed. Also the new "Disease-Oriented Screening System", which is now under development as a new screening system at the National Cancer Institute was also described.

Animals↗
PubMed1987

[Therapeutic approach against drug-resistant tumors and their biochemical nature].

One of the major causes of failure of cancer chemotherapy is the proliferation of specific drug-resistant tumor cells during treatment. Drug-resistant tumor cells, however, usually bear biochemical changes which are related to the resistance mechanisms. New modalities against resistant cells could be possible if we were able to characterize these biochemical changes. Vincristine (VCR)- and adriamycin (ADM)-resistant tumor sublines show cross-resistance (pleiotropic drug resistance) to other unrelated drugs. VCR- and ADM-resistant sublines possess an enhanced outward transport of antitumor agents, which results in a low accumulation of antitumor agents in the cells. The cells express unique glycoproteins in the plasma membrane, and possess a higher calcium content in the cells. They also have double-minute chromosomes and homogeneously staining regions in chromosomes. By targeting for these biochemical changes, we have established new modalities against drug-resistant tumor cells. Calcium channel blockers inhibited the enhanced outward transport of VCR and ADM from resistant tumor cells, and thus overcame resistance to these agents. This approach showed potential usefulness in clinical trials. Another possible approach against drug-resistant tumor cells could be the utilization of monoclonal antibodies against unique glycoproteins in the plasma membrane of resistant tumor cells. We have developed monoclonal antibodies against adriamycin-resistant human myelogenous leukemia K562. Our recent progress with work on calcium channel blockers and monoclonal antibodies are discussed in this paper.

Antibodies, Monoclonal↗
PubMed1987

[Tumor-induced platelet aggregation and growth-promoting factors as determinants of probable tumor metastasis].

Clones isolated from a metastatic variant of mouse colon adenocarcinoma 26; the high metastatic NL-17 and the low metastatic NL-44, induced similar degrees of platelet aggregation in vitro. Heterotypic aggregates of tumor cells and platelets were injected i.v. into mice. The lung colonization potential of NL-17 was dependent upon the extent of tumor cell platelet aggregation. This clearly indicates that the interaction of tumor cells with platelets can lead to enhanced tumor metastasis possibly through more efficient intravascular arrest of the heterotypic aggregates. The interaction of tumor cells with platelets could thus be an important determinant of probable metastasis. NL-44, however, did not form pulmonary metastasis even after the tumor cells had formed heterotypic aggregates with platelets, suggesting that tumor metastasis is dependent on the intrinsic nature of tumor cells. Lung extract enhanced the growth of NL-17 more effectively than that of NL-44. These results suggest that, in addition to the interaction of metastatic cells and platelets, host factors including growth-promoting factors might also have an important role in tumor metastasis.

Adenocarcinoma↗
PubMed1986

Role of heparin in tumor cell-induced platelet aggregation.

B16 mouse melanoma cell lines (B16F1, B16F10 and B16BL6) were able to induce platelet aggregation, and concomitant release of ATP in heparinized platelet-rich plasma (PRP). In citrated PRP, these tumor cells did not induce platelet aggregation. Addition of heparin to citrated PRP enabled these tumor cells to induce aggregation. In heparinized PRP, platelet aggregates induced by B16F10 cells were dissociated by the addition of either 4 mM EDTA, 10 mM CaCl2 or 0.1 micrograms/ml protamine sulfate. B16F10-induced aggregation in heparinized PRP was inhibited by preincubation with anti-fibronectin antibody, but not with antifibrinogen or anti-von Willebrand factor antibodies. B16F10 cells induced aggregation in washed platelet suspension with the addition of heparinized platelet-poor plasma (PPP). Cryoprecipitate from human plasma showed the same effect in the presence of heparin if substituted for PPP. The mixture of purified fibronectin, von Willebrand factor, fibrinogen and heparin were less effective than cryoprecipitate on B16F10-induced aggregation of washed platelets. The results suggest that an interaction between fibronectin and heparin may be important in tumor cell-induced aggregation.

Animals↗
PubMed1986

Effects of cytochalasins and colchicine on the accumulation and retention of daunomycin and vincristine in drug resistant tumor cells.

Cytochalasin B and D enhanced vincristine (VCR) and daunomycin (DAU) accumulation in tumor cells, especially in VCR- and DAU-resistant cell lines. The effect of cytochalasin B, and to a lesser extent cytochalasin D, was almost equivalent to that observed for verapamil, a calcium channel blocker which has been reported to enhance drug accumulation in tumor cells. Cytochalasin B was most effective in VCR- and DAU-sensitive cells; however, the effect in resistant cells was less than that observed for verapamil, suggesting a different mode of action between these drugs in sensitive and resistant cells. Enhanced accumulation of VCR and DAU by cytochalasins was mediated by the inhibition of outward transport of VCR and DAU from tumor cells. Colchicine had no effect on VCR and DAU accumulation. Cytochalasins, especially cytochalasin D is a specific inhibitor of microfilament assembly in cells. These results indicate that the cellular microfilament system plays a prominent role in drug transport of tumor cells, and that an intact microtubular system is less involved.

Animals↗
PubMed1986

Adriamycin accumulation and metabolism in adriamycin-sensitive and -resistant human ovarian cancer cell lines.

Adriamycin accumulation and metabolism were studied in three distinct groups of human ovarian cancer cell lines: those derived from previously untreated patients, those from clinically refractory (relapsed) patients, and those with induced resistance to adriamycin in vitro. The 2-hr [14C] adriamycin accumulation in cell lines from previously untreated patients (A2780 and A1847 [Eva et al., Nature, Lond. 295, 116 (1982)] and OVCAR-5 [National Institutes of Health human OVarian CAR-cinoma cell line no. 5]) was 11-14 ng/10(6) cells. 2780AD and 1847AD (variants with in vitro induced resistance to adriamycin) accumulated one-third as much adriamycin after 2 hr (4 ng/10(6) cells). However, three cell lines derived from clinically refractory patients accumulated the same amount of adriamycin as cell lines from untreated patients (8-13 ng/10(6) cells). A high-performance liquid chromatography (HPLC) assay for adriamycin and its analogs confirmed these results and demonstrated only parent drug (no metabolites) in any of the cell lines tested. These results demonstrate that the primary mechanism of adriamycin resistance in some ovarian cancer cells from clinically refractory patients is not enhanced metabolism of drug or a transport defect leading to a decreased net accumulation such as has been described for cells with in vitro induced resistance to adriamycin.

Cell Line↗
PubMed1986

Activity of tricyclic nucleoside 5'-phosphate in model systems of human ovarian cancer.

Tricyclic nucleoside 5'-phosphate (TCN-P) was evaluated in two models of human ovarian cancer. TCN-P reduced both colony number and volume in clonogenic assays employing human ovarian cancer cell lines. TCN-P cytotoxicity depended on the concentration, exposure duration and cell line studied, but not on cell line plating efficiency or growth rate in soft agarose. Comparison of experimental IC50 concentrations for 1 hour or continuous TCN-P exposure with reported clinically relevant concentrations suggests that therapeutic TCN-P levels are more likely to be achieved by continuous infusions. Cell lines and sublines with resistance to several standard chemotherapeutic agents acquired both in vivo and in vitro were at most 2.6-fold cross-resistant to TCN-P with 1 hour drug exposure. Cross-resistance was not evident with continuous TCN-P exposure. Intermittent bolus TCN-P (100 mg/kg/d X 5) was ineffective in an in vivo xenograft model of human ovarian cancer. These data suggest that TCN-P is most likely to be clinically effective against ovarian cancer, and may be non-cross-resistant with several standard agents, if administered by continuous infusion. Preclinical evaluation of new agents, such as TCN-P, in these experimental models may provide information useful in subsequent clinical trials.

Acenaphthenes↗
PubMed1986

Synthesis and antitumor activity of tropolone derivatives. 3.

As part of a study on the antitumor activities of tropolone derivatives prepared from hinokitiol, which naturally occurs in the plants of Chamaecyparis species, effects of aromatic substituents of alpha,alpha-bis(7-hydroxy-5-isopropyltropon-2-yl)toluenes on the activity were examined. Several of the compounds showed high potency in the P388 leukemia assay. 4-Hydroxy analogue 4d showed the most potent activity (T/C = 195%) at a 5 mg/kg dose. The introduction of large-size substituents, of which the steric influence prevents coplanarity of the substituted aromatic function, resulted in a remarkable decrease in the potency. X-ray structural analysis of highly potent 4-methoxy analogue 4b was undertaken.

Animals↗
PubMed1986

Functional role for the 170- to 180-kDa glycoprotein specific to drug-resistant tumor cells as revealed by monoclonal antibodies.

An overexpression of the plasma membrane glycoprotein of relative molecular size 170-180 kDa is consistently found in different multidrug-resistant human and animal cell lines, although the functional role of the protein in multidrug resistance is not known. Two monoclonal antibodies that interfere with biochemical functions were generated against the human myelogenous leukemia K-562 cells resistant to adriamycin (K-562/ADM). These antibodies, designated MRK16 and MRK17, are specifically reactive to K-562/ADM and a human ovarian cancer cell line resistant to adriamycin (2780AD). MRK16 modulated vincristine and actinomycin D transport in the resistant cells, while MRK17 specifically inhibited the growth of the resistant cells. Both antibodies recognized the 170- to 180-kDa glycoprotein. These data indicate that the 170- to 180-kDa glycoprotein is involved, directly or indirectly, in the drug transport mechanisms and the proliferation of multidrug-resistant tumor cell lines.

Animals↗
PubMed1986

Collateral susceptibility of adriamycin-, melphalan- and cisplatin-resistant human ovarian tumor cells to bleomycin.

Three cell lines resistant to adriamycin, melphalan and cisplatin were established in vitro from human ovarian cancer cell line A2780. Each subline showed a resistance to its inducing drug of 75-fold in the case of adriamycin, 6-fold in the case of melphalan and 11-fold in the case of cisplatin. However, all of these sublines showed collateral sensitivity to bleomycin. Approximately a 2-fold higher susceptibility to bleomycin was observed generally. The biochemical mechanisms of this collateral sensitivity are not clear at present, but the higher concentration of glutathione in these resistant tumor cell lines might be related to the high susceptibility of these resistant cells to bleomycin.

Bleomycin↗
PubMed1986

Characteristics of resistance to adriamycin in human myelogenous leukemia K562 resistant to adriamycin and in isolated clones.

An adriamycin (ADM)-resistant variant (K562/ADM) of human myelogenous leukemia K562 was established. K562/ADM was stable for 2 months in medium without ADM, and was 130-fold more resistant to ADM as compared to the parent K562. Twenty clones were isolated from K562/ADM by the limiting dilution technique. Five clones with different ADM sensitivity were selected and characterized further. The extent of clonal resistance to ADM was parallel to the extent of resistance to vincristine (VCR), except for one clone, KA-15. The majority of clones, including K562/ADM, accumulated far smaller amounts of daunomycin (DAU) or VCR as compared to the parent K562. However, a highly resistant clone did not necessarily accumulate less DAU in the cells, indicating that the mechanism of ADM resistance cannot be explained solely by a defect of ADM accumulation. All clones rapidly transported DAU and VCR from the cells. K562/ADM expressed on the cell surface three distinct glycoproteins with molecular weights of 180,000, 83,000 and 65,000 daltons. No change was detected in the actin and tubulin contents of K562 and clones. K562/ADM and its clones expressed double minute chromosomes and contained homogeneously staining regions in the chromosomes.

Actins↗
PubMed1986

Acquired vs innate multidrug resistance and the effect of calcium channel blockers.

Innate drug resistance as well as acquired multidrug resistance are directly related to ineffectiveness and failure of the cancer chemotherapy. The mechanisms of such resistance, especially those of innate resistance, have not been fully elucidated. We have established vincristine (VCR)- and Adriamycin (ADM)-resistant sublines of human myelogenous leukemia K562 by continuous drug exposure. These resistant sublines contained double minute chromosomes and express a glycoprotein with a 180,000 dalton M.W. Analysis of VCR and ADM sensitivities of several isolated clones from these resistant sublines revealed a tight relationship between these two resistant mechanisms. However, ADM resistant sublines are always highly resistant to VCR, but VCR resistant sublines are not necessarily highly resistant to ADM, suggesting the presence different mechanisms of ADM and VCR resistance. Calcium channel blockers inhibit the drug efflux in these resistant tumor cells, thereby overcoming of drug resistance. Greater potentition was observed with antitumor agents to which VCR- and ADM-resistant cells were highly cross-resistant. Calcium channel blockers always show higher potentiation with VCR than ADM, and the clones with greater resistance to VCR generally accumulated less VCR and generally possessed a higher rate of VCR efflux. These results might indicate that a major mechanism of VCR resistance could be a defficiency in drug transport and this mechanism can be reversed by calcium channel blockers, while the ADM resistance mechanisms are partly related to drug efflux and only this mechanism of the ADM resistance can be modulated by calcium channel blockers. Calcium channel blockers also potentiate the drug effects, especially that of vinca alkaloids, in innately resistant tumors cells, indicating that such innate resistant cells also share a similar resistance mechanism to that observed in acquired drug resistance. From these results, the mechanisms of acquired and innate drug resistance are discussed.

Animals↗
PubMed1986

Augmentation of 1-beta-D-arabinofuranosylcytosine resistance in human KB epidermoid carcinoma cells upon induction of a second resistance to vincristine.

Human KB epidermoid carcinoma cells (KB/p) and their variant cells (KB/ara-C) resistant to 1-beta-D-arabinofuranosylcytosine (ara-C) that were not cross-resistant to vincristine (VCR) were exposed to increasing concentrations of VCR to establish VCR resistant cells (KB/VCR) and doubly resistant variant cells (KB/ara-C/VCR). KB/VCR and KB/ara-C/VCR cells showed a similar increase in resistance to VCR (about 337- to 460-fold) over that of the parent KB/p cells. KB/ara-C showed a 911-fold increase in resistance to ara-C, while KB/ara-C/VCR showed a 60,837-fold increase in resistance to ara-C compared with the parent cells. The concentration of ara-C required for 50% inhibition of KB/ara-C/VCR cells was much higher (67-fold) than that for KB/ara-C cells, although the concentration of ara-C required for 50% inhibition of KB/VCR cells was 12-fold that for KB/p cells. Thus the acquisition of resistance to a second drug by these human KB cells augmented their resistance to the first drug. Induction of resistance to ara-C or VCR resulted in marked decrease in cellular uptake of the respective drugs, but there was no difference in cellular uptakes of ara-C by KB/ara-C and KB/ara-C/VCR or of VCR by KB/VCR and KB/ara-C/VCR. KB/VCR and KB/ara-C/VCR cells were cross-resistant to vinblastine, colchicine, vindesine, etoposide, mitomycin C, and Adriamycin. Cells of the two groups (KB/p and KB/ara-C; KB/VCR and KB/ara-C/VCR) differed in sizes and doubling times. In the absence of ara-C, the resistance of KB/ara-C cells to ara-C was stable for at least 1 year, whereas in the absence of VCR resistance to VCR was almost completely lost within 1 month.

Antineoplastic Agents↗