Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0023473 (chronic myeloid leukemia)
 18,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Resistance to multiple chemotherapeutic agents has been related to the production of P-glycoprotein, a trans-membrane drug efflux pump that is encoded by the multidrug resistance (MDR) gene mdr1. To investigate whether mdr1 could be involved in clinical resistance to chemotherapy in acute leukemias, we have analyzed retrospectively the RNA from adult acute leukemia cells by slot-blot hybridization with a human mdr1 probe. Units of mdr1 expression were defined by reference to drug-sensitive human sarcoma and K562 leukemia cell lines (1 U) and the highly resistant doxorubicin selected leukemia cells K562/R7 (50 U). We studied 41 adult patients with acute leukemias: 5 acute lymphoblastic leukemias, 23 acute myeloid leukemias, and 13 secondary leukemias or blast crisis of chronic myelogenous leukemia. Expression of 10 U or more of mdr1 was found in 6 of 31 (19%) leukemias at diagnosis, versus 5 of 10 (50%) after relapse from therapy, P = .06. The complete remission rate and in vitro sensitivity to daunorubicin were both correlated with low expression (1 U, v 2 U or more) of mdr1. Among 36 evaluable attempts to induce remission, the complete remission rate was 67% (8 of 12) for patients with undetectable or minimal mdr1 expression (1 U), versus 29% (7 of 24) in patients with 2 U or more of expression, P = .03. In vitro resistance to daunorubicin or other MDR-related drugs was associated with expression of 2 U or more of mdr1 in 11 of 11 cases, while specimens that were sensitive to these agents were negative for mdr1 expression in 5 of 11 cases, P = .03. These data suggest that mdr1 expression contributes to chemoresistance in acute leukemia. Determination of mdr1 gene expression may be useful in designing therapy for patients with leukemia.
 ...
PMID:Multidrug resistance (mdr1) gene expression in adult acute leukemias: correlations with treatment outcome and in vitro drug sensitivity. 185 77

We determined the expression levels of the mdr1 and mdr3 multidrug-resistance genes (also known as PGY1 and PGY3, respectively) in peripheral blood cells from 69 adult patients with acute and chronic leukemias, using an RNase protection assay. Expression of mdr1 was found in samples from patients with acute nonlymphocytic leukemia (13 of 17), chronic myelocytic leukemia (CML, chronic phase, 10 of 10; blast crisis, three of four), acute lymphocytic leukemia (ALL, eight of 11), B-cell chronic lymphocytic leukemia (B-CLL, 17 of 17), hairy cell leukemia (HCL, one of two), and T-cell prolymphocytic leukemia (one of one), but not in B-cell prolymphocytic leukemia (B-PLL, 0 of seven). Expression of mdr3 was only detected in samples from B-cell lymphocytic leukemias: CML, lymphoid blast crisis (one of one), B-cell ALL (two of two), B-CLL (17 of 17), B-PLL (seven of seven), and HCL (two of two). In vitro drug uptake studies by on-line flow cytometry showed that in leukemia cells expressing either mdr1 or mdr3, the steady-state accumulation of daunorubicin could be significantly increased by addition of cyclosporine and, to a lesser extent, by verapamil. Because cyclosporine and verapamil are known as inhibitors of the mdr1-encoded P-glycoprotein drug-efflux pump, and because the mdr1 and mdr3 genes are highly homologous, our data suggest that the mdr3 gene encodes a functional drug pump in B-cell lymphocytic leukemias. The results of this study may have implications for clinical therapy for acute or chronic leukemias expressing the mdr1 or mdr3 gene, in particular, treatment with combinations of cytotoxic drugs plus agents that reverse multidrug resistance. Since mdr1 and mdr3 are frequently expressed in untreated as well as treated leukemia, such combination therapy should be considered for untreated patients as well as treated patients.
 ...
PMID:Expression of mdr1 and mdr3 multidrug-resistance genes in human acute and chronic leukemias and association with stimulation of drug accumulation by cyclosporine. 197 61

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.
 ...
PMID:Detection of multidrug resistance markers, P-glycoprotein and mdr1 mRNA, in human leukemia cells. 289 23

The induced expression of multiple drug resistance (MDR)-associated genes as a direct response of tumor cells to antineoplastic drugs could be an important factor influencing the success of cancer chemotherapy. We investigated the effects of such compounds on mdr1/P-glycoprotein (P-gp) gene expression and drug sensitivities in the T-lymphoblastoid human cell line CCRF-CEM and MDR sublines. Thereby, we observed that actinomycin D or adriamycin administered at sublethal concentrations induced increases of mdr1 mRNA levels and resistance within 72 h. Furthermore, on leukemia cell samples collected before and after chemotherapy we checked by a complementary DNA polymerase chain reaction (cDNA-PCR) approach for similar alterations in the relative expression levels of the MDR-associated genes (a) mdr1/P-gp (b) mrp (MDR related protein), and (c) the topoisomerase II isoforms alpha and beta. We found a concomitant increase in mdr1 and mrp gene expression combined with a decreased expression of topoisomerase II alpha in the course of the second relapse of an acute lymphoblastic leukemia (ALL). This points to the emergence of at least three different MDR mechanisms in this type of leukemia unresponsive to chemotherapy. A chronic myeloid leukemia (CML) in blast crisis, however, showed combined increases in mdr1 (about 20-fold) and mrp (about four fold) gene expression after intense but unsuccessful chemotherapy over a 6-month period. Our results indicate the occurrence of induced resistance in vitro and in vivo and suggest a contribution of the newly identified ATP-binding cassette (ABC) transporter MRP in MDR.
 ...
PMID:Drug-induced changes in the expression of MDR-associated genes: investigations on cultured cell lines and chemotherapeutically treated leukemias. 791 48

The non-ionic detergent Tween 80, which is used as a solvent for lipophilic drugs such as VP-16 and Taxotere, was found to reverse VP-16 resistance of the P-glycoprotein-associated multidrug resistance phenotype via increasing VP-16 influx. In adriamycin-resistant human chronic myelogenous leukemia K562 cells (K562/ADM), which overexpress mdr1 mRNA, the accumulation of VP-16 was only about 10% that in wild-type K562 cells. Tween 80 enhanced VP-16 accumulation in K562/ADM cells but did not influence VP-16 accumulation in parental K562 cells. VP-16 efflux was rapid and similar in both sensitive and resistant cell lines and was not blocked by Tween 80 or verapamil. Under glucose-free conditions, VP-16 accumulation in K562/ADM cells was only half of that in K562 cells. Tween 80 increased VP-16 accumulation in K562/ADM cells in glucose-free medium. In growth inhibition assay, Tween 80 reversed K562/ADM sensitivity to VP-16 without cell damage. Taken together, Tween 80 reverses VP-16 sensitivity in multidrug-resistant K562 cells by increasing influx, which is considered to be the primary mechanism of VP-16 resistance in K562/ADM cells.
 ...
PMID:Non-ionic detergent Tween 80 modulates VP-16 resistance in classical multidrug resistant K562 cells via enhancement of VP-16 influx. 1073 19

The present study aims to investigate the role of P glycoprotein and multidrug resistance-associated protein (Mrp2) in the transport of telithromycin, a newly developed ketolide antibiotic, in vitro and in vivo. The in vitro experiments revealed that the intracellular accumulation of telithromycin in adriamycin-resistant human chronic myelogenous leukemia cells (K562/ADR) overexpressing P glycoprotein was significantly lower than that in human chronic myelogenous leukemia cells (K562/S) not expressing P glycoprotein. Cyclosporine significantly increased the intracellular accumulation of telithromycin in K562/ADR cells. When telithromycin was coadministered intravenously with cyclosporine in Sprague-Dawley (SD) rats, cyclosporine significantly delayed the disappearance of telithromycin from plasma and decreased its systemic clearance to 60% of the corresponding control values. Hepatobiliary excretion experiments revealed that cyclosporine almost completely inhibited the biliary clearance of telithromycin, suggesting that telithromycin is a substrate of P glycoprotein and a potential substrate of Mrp2. Moreover, the biliary clearance of telithromycin was significantly decreased by 80% in Eisai hyperbilirubinemic mutant rats with a hereditary deficiency in Mrp2, indicating that Mrp2, as well as P glycoprotein, plays an important role in the biliary excretion of telithromycin. When the effect of telithromycin on the biliary excretion of doxorubicin, a substrate of P glycoprotein and Mrp2, was examined in SD rats, telithromycin significantly decreased the biliary clearance of doxorubicin by 80%. Results obtained from this study indicate that telithromycin is a substrate of both P glycoprotein and Mrp2, and these transporters are involved in the hepatobiliary transport of telithromycin.
 ...
PMID:Involvement of the drug transporters p glycoprotein and multidrug resistance-associated protein Mrp2 in telithromycin transport. 1637 71