Efficiency of P‐glycoprotein–Mediated Exclusion of Rhodamine Dyes from Multidrug‐Resistant Cells is Determined by their Passive Transmembrane Movement Rate

Eytan, Gera D.; Regev, Ronit; Oren, Galit; Hurwitz, Charles; Assaraf, Yehuda G.

doi:10.1111/j.1432-1033.1997.00104.x

Cited by 105 publications

(106 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To our knowledge, only Eytan et al [7] have examined several rhodamine dyes for their P-gp-mediated exclusion from MDR cells. In an effort to define the dye characteristics that allow P-gp to efficiently extrude rhodamine dyes and MDR-type drugs from MDR cells, these authors have compared the levels of dye accumulation in MDR cells using the following parameters: the affinity toward P-gp evident as the apparent K m of ATPase-activity modulation of reconstituted P-gp; the level of maximal stimulation of P-gp ATPase activity; the level of dye binding to artificial membrane; the transmembrane movement rate; and the hydrophobicity.…”

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

“…Although it is well known that rhodamines are P-gp substrates [7,14], quantitative data are lacking. In the present study, we have used a continuous fluorescence assay with different rhodamine analogues to quantify their transport by P-gp in intact cells.…”

mentioning

confidence: 99%

“…P-gp can transport neutral and positively charged molecules but not negatively charged ones. Despite the advances of recent years, we still have an unclear view of the molecular mechanism by which P-gp transports such a wide diversity of compounds across the membrane [5][6][7][8][9].Recently, we have performed several studies using K562 intact cells to describe the kinetics of anthracycline transport in MDR cells in order to predict how modifications in the anthracycline molecule affect its transport characteristics [10][11][12][13]. In the present paper we have used the same cell line to characterize the transport of several rhodamines.…”

mentioning

confidence: 99%

“…Eytan et al [7] have examined seven rhodamine dyes for their P-gp-mediated exclusion from MDR cells, their localization in wild-type drug-sensitive cells, their capacity to stimulate the ATPase activity of P-gp reconstituted in proteoliposomes, and their transmembrane movement rate in artificial liposomes. All these rhodamine dyes were accumulated in wild-type drug-sensitive cells and were localized mainly in the mitochondria.…”

mentioning

confidence: 99%

See 4 more Smart Citations

New insights into the P‐glycoprotein‐mediated effluxes of rhodamines

Loetchutinat

Saengkhae

Marbeuf-Gueye

et al. 2003

European Journal of Biochemistry

View full text Add to dashboard Cite

Multidrug resistance (MDR) in tumour cells is often caused by the overexpression of the plasma drug transporter P-glycoprotein (P-gp). This protein is an active efflux pump for chemotherapeutic drugs, natural products and hydrophobic peptides. Despite the advances of recent years, we still have an unclear view of the molecular mechanism by which P-gp transports such a wide diversity of compounds across the membrane. Measurement of the kinetic characteristics of substrate transport is a powerful approach to enhancing our understanding of their function and mechanism. The aim of the present study was to further characterize the transport of several rhodamine analogues, either positively charged or zwitterionic. We took advantage of the intrinsic fluorescence of rhodamines and performed a flow-cytometric analysis of dye accumulation in the wild-type drug sensitive K562 that do not express P-gp and its MDR subline that display high levels of MDR. The measurements were made in real time using intact cells. The kinetic parameter, k a ¼ V M /k m , which is a measure of the efficiency of the P-gp-mediated efflux of a substrate was similar for almost all the rhodamine analogues tested. In addition these values were compared with those determined previously for the P-gp-mediated efflux of anthracycline. Our conclusion is that the compounds of these two classes of molecules, anthracyclines and rhodamines, are substrates of P-gp and that their pumping rates at limiting low substrate concentration are similar. The findings presented here are the first to show quantitative information about the kinetic parameters for P-gp-mediated efflux of rhodamine analogues in intact cells.Keywords: P-glycoprotein; multidrug resistance; membrane transport; rhodamine; efflux. Since 1940, a broad variety of antibiotics active against many infectious organisms were discovered or developed. The widespread, and sometimes uncontrolled, use of these drugs has led to the emergence of defence mechanisms that, at present, are the major drawback of the drug-based treatment of infectious diseases and cancers. Such resistance is not restricted to the drugs (or analogues) used in the treatment but also involves several structurally and functionally unrelated compounds. This phenomenon, which has been termed multidrug resistance (MDR), can be caused by various mechanisms. However, over expression of the P-glycoprotein multidrug transporter (P-gp) in the plasma membrane is believed to be a major cause of resistance to multiple chemotherapeutic drugs [1][2][3][4]. P-gp is an unusual ABC protein in that it appears to be highly promiscuous: hundreds of compounds have been identified as substrates. The spectrum of MDR compounds includes a large number of anticancer drugs (e.g. anthracyclines, vinca alkaloids, taxanes) as well as steroids, fluorescent dyes, rhodamines, and the c-emitting radio pharmaceutical 99m Tc-MIBI. P-gp can transport neutral and positively charged molecules but not negatively charged ones. Despite the advances of recent years, we still h...

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

New insights into the P‐glycoprotein‐mediated effluxes of rhodamines

Loetchutinat

Saengkhae

Marbeuf-Gueye

et al. 2003

European Journal of Biochemistry

View full text Add to dashboard Cite

show abstract

Polyoxovanadates as new P‐glycoprotein inhibitors: insights into the mechanism of inhibition

et al. 2021

View full text Add to dashboard Cite

A promising strategy to overcome multidrug resistance is the use of inhibitors of ABC drug transporters. For this reason, we evaluated the polyoxovanadates (POVs) [V 10 O 28 ] 6-(V 10 ), [H 6 V 14 O 38 (PO 4 )] 5− (V 14 ), [V 15 O 36 Cl] 6− (V 15 ) and [V 18 O 42 I] 7− (V 18 ) as inhibitors of three major multidrug resistance-linked ABC transporters: P-glycoprotein (P-gp), ABCG2 and MRP1. All of the POVs selectively inhibited P-gp. V 10 and V 18 were the two most promising compounds, with IC 50 values of transport inhibition of 25.4 and 22.7 µM, respectively. Both compounds inhibited P-gp ATPase activity, with the same IC 50 value of 1.26 µM. V 10 and V 18 triggered different conformational changes in the P-gp protein with time-dependent inhibition, which was confirmed using the synthesized salt of V 10 with rhodamine B, RhoB-V 10 . The hydrophilic nature of POVs supports the hypothesis that these compounds target an unusual ligand-binding site, opening new possibilities in the development of potent modulators of ABC transporters.

show abstract