Characterization of the Transport of Nucleoside Analog Drugs by the Human Multidrug Resistance Proteins MRP4 and MRP5

Abstract

The human multidrug resistance proteins MRP4 and MRP5 are organic anion transporters that have the unusual ability to transport cyclic nucleotides and some nucleoside monophosphate analogs. Base and nucleoside analogs used in the chemotherapy of cancer and viral infections are potential substrates. To assess the possible contribution of MRP4 and MRP5 to resistance against these drugs, we have investigated the transport mediated by MRP4 and MRP5. In cytotoxicity assays, MRP4 conferred resistance to the antiviral agent 9-(2-phosphonomethoxyethyl)adenine (PMEA) and high-performance liquid chromatography analysis showed that, like MRP5, MRP4 transported PMEA in an unmodified form. MRP4 also mediated substantial resistance against other acyclic nucleoside phosphonates, whereas MRP5 did not. Apart from lowlevel MRP4-mediated cladribine resistance, the cytotoxicity of clinically used anticancer nucleosides was not influenced by overexpression of MRP4 or MRP5. In contrast, MRP5 mediated efflux of the pyrimidine-based antiviral 2Ј,3Ј-dideoxynucleoside 2Ј,3Ј-didehydro-2Ј,3Ј-dideoxythymidine 5Ј-monophosphate (d4TMP) and its phosphoramidate derivative alaninyl-d4TMP from cells loaded with the 2Ј,3Ј-didehydro-2Ј,3Ј-dideoxythymidine prodrugs cyclosaligenyl-d4TMP and aryloxyphosphoramidate d4TMP (So324), respectively. Moreover, only inside-out membrane vesicles derived from MRP5-overexpressing cells accumulated alaninyl-d4TMP. Cellular efflux and vesicular uptake studies were carried out to further compare transport mediated by MRP4 and MRP5 and showed that dipyridamole, dilazep, nitrobenzyl mercaptopurine riboside, sildenafil, trequinsin and MK571 inhibited MRP4 more than MRP5, whereas cyclic nucleotides and monophosphorylated nucleoside analogs were equally poor inhibitors of both pumps. These results strongly suggest that the affinity of MRP4 and MRP5 for nucleotide-based substrates is low.

Increased levels and defective glycosylation of MRPs in ovarian carcinoma cells resistant to oxaliplatin

“…The electrophoretic mobility of vitro for drug resistance [32], but no evidence of resistance to Pt drugs in cells overexpressing exogenous MRP1 has been provided [33]. In the present study, the employed gain of function approach suggests that, at least in ovarian carcinoma models, oxaliplatin and cisplatin are substrates for MRP1 and MRP4, which appear to transport also topotecan, a known MRP4 substrate, and 6-mercaptopurine, one of the most important substrates of MRP4 [34][35][36].…”

MRP8/ABCC11 directly confers resistance to 5-fluorouracil

“…MRP/ABCC family members can be subdivided into two groups: (a) ABCC1-3, ABCC6, and ABCC10, which contain 17 transmembrane segments; and (b) ABCC4, ABCC5, ABCC11, and ABCC12, which lack one of the transmembrane regions and have only 12 transmembrane segments (5). Some studies have shown that later group members (although ABCC12 is still under investigation) are transporters of cyclic nucleosides and nucleoside analogues due to the active efflux of the monophosphorylated metabolites of these drugs (6,7,10). Furthermore, recent transfection studies have showed that ABCC5 and ABCC11 are able to efflux FdUMP, which is the monophosphorylated and active metabolite of 5-FU (10,12).…”

Single-step doxorubicin-selected cancer cells overexpress the ABCG2 drug transporter through epigenetic changes

“…Parental HEK293 cells (293 human embryonic kidney cells) and the MRP4-overexpressing HEK293/ 4.63 cells were gifts of P Borst (The Netherlands Cancer Institute, Amsterdam, The Netherlands) (Wielinga et al, 2002). HEK293/4.63 cells were reported to express significantly more MRP4 (Reid et al, 2003) without overexpression of other ABC drug transporters and were cultured as previously described (Wu et al, 2005). The ovarian IGROV-1 cells were obtained from the Developmental Therapeutics Program, NCI.…”