Effect of fludarabine and arabinosylcytosine on multidrug resistant cells (original) (raw)
Related papers
Blood, 1999
The expression of P-glycoprotein (Pgp) is often increased in acute myeloid leukemia (AML). However, little is known of the regulation of Pgp expression by cytotoxics in AML. We examined whether Pgp expression and function in leukemic blasts was altered after a short exposure to cytotoxics. Blasts were isolated from 19 patients with AML (15 patients) or chronic myeloid leukemia in blastic transformation (BT-CML, 4 patients). Pgp expression and function were analyzed by flow cytometric analysis of MRK 16 binding and Rhodamine 123 retention, respectively. At equitoxic concentrations, ex vivo exposure for 16 hours to the anthracyclines epirubicin (EPI), daunomycin (DAU), idarubicin (IDA), or MX2 or the nucleoside analogue cytosine arabinoside (AraC) differentially upregulated MDR1/Pgp expression in Pgp-negative and Pgp-positive blast cells. In Pgp-negative blasts, all four anthracyclines and AraC significantly increased Pgp expression (P =.01) and Pgp function (P =.03). In contrast, MX2...
Isolation and characterization of an anthracycline-resistant human leukemic cell line
Cancer research, 1985
An anthracycline-resistant subline of HL-60 promyelocytic leukemia cells (HL-60/AR) has been isolated in vitro by subculturing in progressively higher concentrations of Adriamycin. The resistant cells are capable of sustaining continuous growth in 10(-6) M Adriamycin which is more than 50 times the 50% inhibitory dose for the parent line. HL-60/AR expressed variable degrees of cross-resistance to daunorubicin, dihydroxyanthracenedione, vincristine, vinblastine, and actinomycin D, but it remained sensitive to methotrexate and 1-beta-D-arabinofuranosylcytosine. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of glycoproteins of HL-60/AR revealed two prominent glycoproteins with molecular weights of 160,000 +/- 10,000 and 110,000 +/- 10,000 which were not detected in the sensitive cells. Cellular uptake and retention of daunorubicin was studied in the resistant and sensitive cells utilizing digitized video fluorescence microscopy. The sensitive cells accumulated more drug and...
Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1999
Multidrug resistance (MDR) in model systems is known to be conferred by two different integral proteins, the 170-kDa Pglycoprotein (Pgp) and the 190-kDa multidrug resistance-associated protein (MRP 1 ). One possible pharmacological approach to overcome drug resistance is the use of specific inhibitors, which enhance the cytotoxicity of known antineoplastic agents. However, while many compounds have been proven to be very efficient in inhibiting Pgp activity only some of them are able to inhibit MRP 1 . The other likely approach is based on the design and synthesis of new non-crossresistant drugs with physicochemical properties favoring the uptake of the drug by the resistant cells. The intracellular drug retention influences its cytotoxic effect. The level of the intracellular drug content is a function of the amount of drug transported inside the cell (influx) and the amount of drug expelled from the cell (efflux). In this work, the kinetics of drug uptake and the kinetics of active efflux of several anthracycline derivatives in both Pgp expressing K562/Adr cells and MRP 1 expressing GLC4/Adr cells was determined. Our data have shown that in both cell lines there is no correlation between the resistance factor and the kinetics of drug efflux by these pumping systems. However, a very good correlation between the resistance factor and the kinetics of drug uptake has been established in both cell lines: the resistance factor decreases when the kinetics of drug uptake increases. This work has clearly shown that when the rate of transmembrane transport of anthracycline is high enough, the efflux mediated by the protein transporter is not able to pace with it. The protein transporter essentially operates in a futile cycle and the resistance factor is tending to one. It does not mean, however, that when the resistance factor is close to one the anthracycline is not transported by the pump. ß 1999 Elsevier Science B.V. All rights reserved. 0167-4889 / 99 / $^see front matter ß 1999 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 -4 8 8 9 ( 9 9 ) 0 0 0 6 0 -9 * Corresponding
British journal of cancer, 1999
The effects of 4-demethoxydaunorubicin (idarubicin, IDA) and MX2, a new morpholino-anthracycline, on up-regulation of the MDR1 gene in the low-level multidrug resistant (MDR) cell line CEM/A7R were compared at similar concentrations (IC10, IC50 and IC90) over a short time exposure (4 and 24 h). The chemosensitivity of each drug was determined by a 3-day cell growth inhibition assay. Compared with epirubicin (EPI), IDA and MX2 were 17- and eightfold more effective in the CEM/A7R line respectively. No cross-resistance to 5-FU was seen in the CEM/A7R line. Verapamil (5 microM) and PSC 833 (1 microM), which dramatically reversed resistance to EPI in the CEM/A7R line, had no sensitizing effect on the resistance of this line to MX2, but slightly decreased resistance to IDA. The sensitivity to 5-FU was unchanged by these modulators. The induction of MDR1 mRNA expression by IDA, MX2 and 5-FU was analysed by Northern blotting and semiquantitatively assessed by scanning Northern blots on a ph...
Anthracycline Resistance in P388 Murine Leukemia and Its Circumvention by Calcium Antagonists1
2000
Daunorubicin transport was compared in P388 murine leuke mia and in P388/Adramycin (ADR), an anthracycline-resistant subline. We can demonstrate an energy-dependent outward transport system in P388/ADR which limits drug accumulation. Although no calcium requirement for the outward transport proc ess could be shown, several calcium antagonists inhibited out ward transport of daunorubicin in P388/ADR and modified the drug resistance pattern.
Analysis of Drug Transport Kinetics in Multidrug-resistant Cells: Implications for Drug Action
Current Medicinal Chemistry, 2001
Multidrug resistance (MDR) in model systems is known to be conferred by two different integral proteins--the 170-kDa P-glycoprotein (P-gp) and the 190-kDa multidrug resistance-associated protein (MRP1)--that pump drugs out of MDR cells. The intracellular level of a drug, which influences the drug's cytotoxic effect, is a function of the amount of drug transported inside the cell (influx) and the amount of drug expelled from the cell (efflux). One possible pharmacological approach to overcoming drug resistance is the use of specific inhibitors that enhance the cytotoxicity of known antineoplastic agents. Many compounds have been proven to be very efficient in inhibiting P-gp activity, but only some of them can inhibit MRP1. However, the clinical results obtained so far by this approach have been rather disappointing. The other likely approach is based on the design and synthesis of new non-cross-resistant drugs whose physicochemical properties favor the uptake of such drug by resistant cells. Our recent studies have shown that whereas the P-gp-and MRP1mediated efflux of different anthracycline-based drugs may not differ considerably, their kinetics of uptake do. Thus, the high uptake of drug by cells may lead to concentrations at the cellular target site high enough to achieve the needed cytotoxicity against MDR cells. Therefore, increased drug lipophilicity might be one factor in improving drug cytotoxicity in MDR cells. In vitro studies have shown that idarubicin, an analogue of daunorub cin, is more effective than daunorubicin and doxorubicin against MDR tumor cell lines and that this increased effectiveness is related in part to the increased lipophilicity of idarubicin. Other studies have also confirmed the strong impact of lipophilicity on the uptake and retention of anthracyclines in MDR cells.
In vitro analysis of drug resistance in tumor cells from patients with acute myelocytic leukemia
Medical oncology and tumor pharmacotherapy, 1992
A 72 hours fluorometric microculture cytotoxicity assay (FMCA) was used for the study of chemotherapeutic drug resistance in tumor cell suspensions from patients with acute myelocytic leukemia (AML). A marked heterogeneity with respect to sensitivity was observed for a panel of cytotoxic drugs tested in 76 samples from 60 patients with treated or untreated AML. Primary resistance to vincristine (Vcr) and prednisolone in untreated AML was observed as well as 'acquired' resistance to several other antileukemic drugs. Cross resistance patterns for AML active drugs revealed significant positive relationships between anthracyclines, VP16 and amsacrine (Amsa), whereas mitoxantrone (Mitox) was more weakly correlated. Sensitivity to cytosine arabinoside was unrelated to the anthracyclines, VP16, Amsa and Mitox but showed a significant relationship to 6-thioguanine. Several resistance modifying agents, including the novel non-immunosuppressive cyclosporin A analogue PSC 833, were abl...
Cellular resistance to anthracyclines
General Pharmacology: The Vascular System, 1996
The antracyclines induce muhiple intraceUular effects; however, inhibition of the nuclear enzyme topoisomerase II (TOPO II) is the main mechanism of action. Resistance to anthracyclines in tumor ceils is muhifactorial. The main mechanisms are: (1) the classic muhidrug resistance (MDR) phenotype, which is due to the presence of P-glycoprotein (PGP) in plasma membrane, that is, a Upump" that can extrude a wide range of anticancer drugs. Membrane-active drugs (e.g., verapamil) have been found in vitro to reverse this phenotype. Most clinical studies including chemosensitizers have, however, been disappointing. (2) Non.PGP-mediated MDR: this phenotype is characterized by expression of other proteins in the plasma membrane which are also able to extrude anticancer drugs. (3) Changes in the intracellular distribution of drug: this mechanism has been demonstrated in several cell lines, most often in combination with PGP or non-PGP-mediated resistance. (4) Glutathione transferases (GST) and detoxification mechanisms: these represent a muhigene family of enzymes that conjugate glutathione to chemically reactive groups. Direct evidence for a causative role of GST in anthracycline resistance is missing. (5) Alterations in TOPO II (at-MDR): DNA topoisomerases are involved in several aspects of DNA metabolism, in particular genetic recombination, DNA transcription, and chromosome segregation. Low levels of expression or alterations in TOPO II are associated in vitro with resistance. (6) Increased DNA repair: in several cell lines, an increase in the efficacy of DNA repair has been associated with resistance to doxorubicin (DOX). So far, only classic MDR has been shown to contribute to resistance in clinical conditions, whereas evidence for the other mechanisms of resistance is still missing. GEN PrtARMAC 27;2:251-255, 1996.