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Biomedical subjects

K Yusa

Publications and source records attributed to K Yusa.

28 records · Page 2Linked to original sources
PubMed1990

Protozoan myoglobin from Paramecium caudatum. Its autoxidation reaction and hemichrome formation.

Native oxymyoglobin (MbO2) was isolated directly from the cells of Paramecium caudatum with complete separation from metmyoglobin (metMb) on a DEAE-cellulose column. It was examined for its spectral and stability properties. When compared with sperm whale MbO2 used as a reference, Paramecium MbO2 was found to be much more susceptible to autoxidation over a wide range of pH (4-11) in 0.1 M buffer at 25 degrees C. Kinetic analysis has revealed that a proton-catalyzed displacement of O2- from MbO2 by an entering water molecule can play a dominant role in the autoxidation reaction of Paramecium MbO2 to metMb, as in the case of sperm whale MbO2 involving the distal histidine as its catalytic residue. At pH values higher than 9.5, however, Paramecium MbO2 was found to be oxidized to yield a hemichrome. The spontaneous formation of hemichromes is at variance with the other known myoglobins and is therefore discussed in relation to the unusual amino acid sequence of Paramecium myoglobin having a large number of deletion.

Animals↗
PubMed1990

Cross-resistance to anti-HIV nucleoside analogs in multidrug-resistant human cells.

Human multidrug-resistant K562/ADM cells showed 12-fold and 31-fold resistance to AZT (3'-azido-2', 3'dideoxythymidine) and DDC (2', 3'-dideoxycytidine), respectively. Other multidrug-resistant human cells CEM/VLB100 and AdrRMCF-7 also showed resistance to these nucleoside analogs. However, verapamil (10 microM) failed to reverse the resistance to the nucleoside analogs. Accumulation of [3H]AZT in human multidrug-resistant K562/ADM, CEM/VLB100 and AdrRMCF-7 cells decreased by 23, 35, and 42% respectively, as compared to their parental cells. These results suggest that anti-HIV nucleoside analogs including AZT, DDC could be transported by outward drug-transport system in the multidrug-resistant cells.

Biological Transport↗
PubMed1989

A fluorine-containing anthracycline (ME2303) as a new antitumor agent against murine and human tumors and their multidrug-resistant sublines.

A new fluorine-containing anthracycline derivative, ME2303, showed excellent antitumor activity against various experimental tumor models. The i.p. or i.v. administrations of ME2303 on Day 1 or on Days 1, 5, and 9 against i.p.-implanted L1210 leukemia cells rendered more than 50% of mice tumor free at wide ranges of nontoxic doses, whereas the incidence of cure obtained with Adriamycin (ADM) was less than that obtained with ME2303. ME2303 given i.p. or i.v. on Day 1 or Days 1, 5, and 9 was also effective against i.p.-implanted P388 leukemia cells, and higher incidences of cure were obtained than with ADM. ME2303 administered i.v. on Days 1, 8, 15, and 22 showed prominent antitumor activity against s.c.-implanted colon adenocarcinomas 26 and 38, Lewis lung carcinoma, B16 melanoma, and M5076 sarcoma. Against colon adenocarcinoma 26, ME2303 induced cure in 16 of 20 mice at doses of 35 to 71 mumol/kg, whereas no cure was observed with ADM. Significant growth inhibition of colon adenocarcinoma 38, Lewis lung carcinoma, B16 melanoma, and M5076 sarcoma cell lines was also observed at a dose of 18 to 106 mumol/kg. ME2303 was effective against human and murine multidrug-resistant cells in vitro. For example, human myelogenous leukemia K562 resistant to ADM (K562/ADM) was only 2.8-fold more resistant to ME2303, while the cells were 200-fold more resistant to ADM when the values for the concentration of drug required for 50% inhibition of cell growth were compared. ME2303 was also more effective than ADM against human leukemia CCRF-CEM resistant to vinblastine, human ovarian carcinoma A2780 resistant to ADM, human epidermoid carcinoma KB cells resistant to colchicine, and mouse leukemia P388 resistant to ADM and vincristine. Therapeutic effects were obtained in vivo against ADM- and, especially, vincristine-resistant P388 leukemia. ME2303 is one of the most interesting potential antitumor agents to be studied further.

Animals↗
PubMed1989

Reversal mechanism of multidrug resistance by verapamil: direct binding of verapamil to P-glycoprotein on specific sites and transport of verapamil outward across the plasma membrane of K562/ADM cells.

The calcium channel blocker verapamil has been shown to reverse multidrug resistance (T. Tsuruo et al., Cancer Res. 41: 1967-1972, 1981), but the mechanism of action of this agent has not been fully elucidated. A radioactive photoactive analogue of verapamil, N-[benzoyl-3,5-3H-(+/-)-5-[(3,4-dimethoxyphenetyl)methylamino]-2- (3,4-dimethoxyphenyl)-2-isopropyl-N-p-azidobenzoylpentylamine, was used to label the plasma membranes of a human myelogenous leukemia cell line (K562), a multidrug-resistant subline selected for resistance to Adriamycin (K562/ADM) and its revertant cell (R1-3). Sodium dodecyl sulfate-polyacrylamide gel electrophoretic fluorograms revealed the presence of an intensely radiolabeled Mr 170,000-180,000 protein in the membranes from K562/ADM but not from the drug-sensitive parental K562 and revertant R1-3 cells. The Mr 170,000-180,000 verapamil acceptor was immunoprecipitated by monoclonal antibody MRK16 specific for P-glycoprotein associated with multidrug resistance, indicating that P-glycoprotein in the plasma membrane is a major target of verapamil in K562/ADM cells. The photolabeling of P-glycoprotein with N-[benzoyl-3,5-3H]-(+/-)-5-[(3,4-dimethoxyphenetyl)methylamino]-2- (3,4-dimethoxyphenyl)-2-isopropyl-N-p-azidobenzoylphentylamine was significantly blocked by other calcium channel blockers, nicardipine and diltiazem, that have been shown to overcome multidrug resistance. In addition, the photolabeling was partially blocked by Adriamycin, vincristine, and colchicine, suggesting that the specific binding sites for verapamil on P-glycoprotein are closely related to the binding sites for these calcium channel blockers and antitumor agents. To determine whether verapamil could be a substrate for P-glycoprotein, the cellular accumulation of [3H]verapamil into K562 and K562/ADM was evaluated. The accumulation of [3H]verapamil in the multidrug-resistant cells was 30% of K562 cells and increased when K562/ADM cells were treated with vincristine and nicardipine at 5 microM, indicating that the P-glycoprotein transports verapamil as well as other antitumor agents in the multidrug-resistant cells. These results suggest that verapamil enhances antitumor agent retention through competition for closely related binding sites on P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

Steroid hormones inhibit binding of Vinca alkaloid to multidrug resistance related P-glycoprotein.

Multidrug-resistant cells are characterized by the presence of P-glycoprotein on the plasma membrane, which binds and probably transports antitumor agents outside the cells. P-glycoprotein is also present in various normal tissues such as the adrenal gland. To investigate the physiological function of P-glycoprotein, we examined possible endogenous materials which inhibit the binding of vincristine to the resistant cell membrane. The binding was inhibited by steroid hormones, most efficiently by progesterone. Progesterone also reduced the photoaffinity labeling of P-glycoprotein by a photoactive analogue of vindesine. These results suggest that P-glycoprotein in the adrenal gland could have a role in the secretion of steroid hormones.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1989

Antitumor activity of ME2303, a fluorine-containing anthracycline, against human tumors implanted in nude mice.

A fluorine-containing anthracycline, ME2303, given intravenously once a week for 4 weeks at the maximum tolerated doses showed better therapeutic effects against 2 gastric, 3 lung and 2 human breast tumor xenografts than did adriamycin (ADM) at the maximum tolerated dose. Among the tumors, ME2303 showed a better effect against St-40, a well-differentiated human gastric adenocarcinoma, against which ADM showed only a marginal effect. Likewise, ME2303 was more effective against Lu-24 human small cell carcinoma and MX-1 human medullary tubular adenocarcinoma than ADM. Notably, the Lu-24 tumor, developed in nude mice, disappeared after the treatment in 3 out of 6 mice. ME2303 would be an interesting compound for phase I and II clinical studies in the future.

Animals↗
PubMed1988

Comparison of glutathione S-transferase activity between drug-resistant and -sensitive human tumor cells: is glutathione S-transferase associated with multidrug resistance?

We have studied the levels of glutathione S-transferase in drug-resistant and -sensitive human tumor cell lines to examine a possible involvement of glutathione S-transferase (GST) in multidrug resistance mechanisms. No increase in the activity of glutathione S-transferase was detected in myelogenous leukemia K562 resistant to adriamycin (K562/ADM), ovarian carcinoma cell line A2780 resistant to adriamycin (2780AD), or acute lymphoblastic leukemia cell line CCRF-CEM resistant to vinblastine (CEM-VLB100), compared with the drug-sensitive parent tumor cells. The human breast cancer cell lines Hattori and MCF-7 had a 12- to 63-fold lower level of glutathione S-transferase activity than K562, A2780, CCRF-CEM, and their drug-resistant sublines. Induction of ADM resistance in Hattori did not increase the activity of glutathione S-transferase. However, induction of colchicine resistance in MCF-7 resulted in a 70-fold increase in the activity of glutathione S-transferase. A revertant of the colchicine-resistant MCF-7 contained a level of glutathione S-transferase activity similar to that of the resistant subline. The increase of glutathione S-transferase activity did not alter the sensitivity of the cell to cytotoxic drugs. The increased activity was due to the appearance of glutathione S-transferase pi, as shown by enzyme inhibition using anti-glutathione S-transferase pi antibody. Our findings indicate that increased cellular glutathione S-transferase activity is not associated with the development of multidrug resistance.

Antineoplastic Agents↗
PubMed1987

Oxidation of oxymyoglobin to metmyoglobin with hydrogen peroxide: involvement of ferryl intermediate.

Hydrogen peroxide, one of the potent oxidants in muscle tissues, can induce very rapid oxidation of oxymyoglobin (MbO2) to metmyoglobin (metMb) with an apparent rate constant of 7.5 X 10(4) h-1 M-1 (i.e., 20.8 s-1 M-1) over the wide pH range of 5.5-10.2 in 0.1 M buffer at 25 degrees C. Its molecular mechanism, however, is quite different from that of the autoxidation of MbO2 to metMb. Kinetic analysis has revealed that the hydrogen peroxide oxidation proceeds through the formation of ferryl-Mb(IV) from deoxy-Mb(II), which is in equilibrium with MbO2, by a two-equivalent oxidation with H2O2. Once the ferryl species is formed, it reacts rapidly with another deoxy-Mb(II) in a bimolecular fashion so as to yield 2 mol of metMb(III). Under physiological conditions, the rate-determining step was the oxidation of the deoxy species by H2O2, its rate constant being estimated to be on the order of 3.6 X 10(3) s-1 M-1 at 25 degrees C. These findings leads us to the view that a good supply of dioxygen provides rather an important defense against the oxidation of myoglobin with hydrogen peroxide in cardiac and skeletal muscle tissues.

Animals↗
PubMedDate not supplied

Cross-resistance of human multidrug-resistant cells to mitomycin C.

Human multidrug-resistant cells, K562/ADM, KB-C-4, AdrRMCF-7 and CEM/VLB100 showed 21-, 7.5-, 105- and 3.4-fold cross-resistance to mitomycin C (MMC). The resistance to MMC in K562/ADM, KB-C-4, AdrRMCF-7, CEM/VLB100 cells was reversed by 6.6 microM verapamil. Accumulation of [3H]MMC in K562/ADM, AdrRMCF-7 and CEM/VLB100 cells also decreased by 37, 26 and 33%, as compared with their drug-sensitive counterparts. In KB-C-4 cells, accumulation of [3H]MMC decreased by 60%, and efflux rate of [3H]MMC was slightly increased as compared to their parental KB-3-1 cells. Verapamil at 6.6 microM increased accumulation of [3H]MMC in these multidrug-resistant sublines. K562/ADM10, K562/ADM50, K562/ADM100 and K562/ADM250 cells, which showed 17- to 230-fold resistance to Adriamycin, also showed 0.8- to 7.3-fold cross-resistance to MMC. In these cell lines, the extent of resistance to Adriamycin (ADM) that was consistent with expression levels of P-glycoprotein shown by immunoblotting was directly proportional to the extent of their resistance to MMC. Regression analysis indicated that relative resistance to Adriamycin was correlated with relative resistance to MMC (r = 0.98). These results indicate that MMC can be transported by P-glycoprotein overexpressed in multidrug-resistant cells.

Doxorubicin↗