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Partial inhibition of the P-glycoprotein-mediated transport of anthracyclines in viable resistant K562 cells after irradiation in the presence of a verapamil analogue.

Abstract：

:P-glycoprotein (P-gp) is a membranous ATPase responsible for the multidrug resistance phenotype. The effect on P-gp-mediated transport of anthracyclines of cell irradiation in the presence of 2,2-diphenyl-5-[N-1-(o-azidophenyl)ethylamino]valeronitrile (VP*), a photoactivable analogue of verapamil was studied in viable K562/ADR cells. The derivatives were daunorubicin (DNR), idarubicin (IDA), 8-(S)-fluoro-idarubicin (F-IDA), 2'-bromo-4'-epidaunorubicin (Br-DNR) and pirarubicin (PIRA). It was observed that the irradiation in the presence of the verapamil analogue was unable to completely inhibit the P-gp-mediated efflux of anthracyclines and we estimated that P-gp retained 10-20% of its ability to pump these toxins. The ability of verapamil, DNR, IDA, F-IDA, Br-DNR and PIRA to inhibit the effect of VP* was studied. For this purpose, cells were irradiated in the presence of VP* and various concentrations of either verapamil or of one of the anthracyclines and then the P-gp functionality was checked by its ability to pump pirarubicin. It was observed that (i) the effect observed, when cells were irradiated in the presence of VP*, was completely blocked by the presence of verapamil; (ii) that anthracyclines are able to partially inhibit the VP* effect. This inhibition occurs at low concentration of anthracycline and depends on the nature of the derivative used. With those used in that study, after the photoirradiation of K562 ADR cells in the presence of VP* and anthracycline, P-gp has retained 50 +/- 5% of its functionality. The anthracycline concentration required for this inhibition is rather low, the total drug concentration yielding 50% of the effect ranged from 0.5 (Br-DNR) to 4 microM (F-IDA). The corresponding cytosolic concentrations are highly correlated with the values of Km determined previously.

journal_name

Chem Biol Interact

journal_title

Chemico-biological interactions

authors

Mankhetkorn S,Teodori E,Garnier-Suillerot A

doi

10.1016/s0009-2797(99)00095-2

subject

Has Abstract

pub_date

1999-07-01 00:00:00

pages

125-40

issue

eissn

0009-2797

issn

1872-7786

pii

S0009-2797(99)00095-2

journal_volume

121

pub_type

杂志文章

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Partial inhibition of the P-glycoprotein-mediated transport of anthracyclines in viable resistant K562 cells after irradiation in the presence of a verapamil analogue.