Multidrug Resistance-associated Protein 2 (MRP2) mediated transport of Oxaliplatin-derived platinum in membrane vesicles

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aut.relation.issue7en_NZ
aut.relation.startpagee0130727
aut.relation.volume10en_NZ
aut.researcherLi, Yan
dc.contributor.authorMyint, Ken_NZ
dc.contributor.authorLi, Yen_NZ
dc.contributor.authorPaxton, Jen_NZ
dc.contributor.authorMcKeage, Men_NZ
dc.date.accessioned2015-08-26T04:27:48Z
dc.date.available2015-08-26T04:27:48Z
dc.date.copyright2015-07-08en_NZ
dc.date.issued2015-07-08en_NZ
dc.description.abstractThe platinum-based anticancer drug oxaliplatin is important clinically in cancer treatment. However, the role of multidrug resistance-associated protein 2 (MRP2) in controlling oxaliplatin membrane transport, in vivo handling, toxicity and therapeutic responses is unclear. In the current study, preparations of MRP2-expressing and control membrane vesicles, containing inside-out orientated vesicles, were used to directly characterise the membrane transport of oxaliplatin-derived platinum measured by inductively coupled plasma mass spectrometry. Oxaliplatin inhibited the ATP-dependent accumulation of the model MRP2 fluorescent probe, 5(6)-carboxy-2,'7'-dichlorofluorescein, in MRP2-expressing membrane vesicles. MRP2-expressing membrane vesicles accumulated up to 19-fold more platinum during their incubation with oxaliplatin and ATP as compared to control membrane vesicles and in the absence of ATP. The rate of ATP-dependent MRP2-mediated active transport of oxaliplatin-derived platinum increased non-linearly with increasing oxaliplatin exposure concentration, approaching a plateau value (Vmax) of 2680 pmol Pt/mg protein/10 minutes (95%CI, 2010 to 3360 pmol Pt/mg protein/10 minutes), with the half-maximal platinum accumulation rate (Km) at an oxaliplatin exposure concentration of 301 μM (95% CI, 163 to 438 μM), in accordance with Michaelis-Menten kinetics (r2 = 0.954). MRP2 inhibitors (myricetin and MK571) reduced the ATP-dependent accumulation of oxaliplatin-derived platinum in MRP2-expressing membrane vesicles in a concentration-dependent manner. To identify whether oxaliplatin, or perhaps a degradation product, was the likely substrate for this active transport, HPLC studies were undertaken showing that oxaliplatin degraded slowly in membrane vesicle incubation buffer containing chloride ions and glutathione, with approximately 95% remaining intact after a 10 minute incubation time and a degradation half-life of 2.24 hours (95%CI, 2.08 to 2.43 hours). In conclusion, MRP2 mediates the ATP-dependent active membrane transport of oxaliplatin-derived platinum. Intact oxaliplatin and its anionic monochloro oxalate ring-opened intermediate appear likely candidates as substrates for MRP2-mediated transport.en_NZ
dc.identifier.citationPLoS ONE 10(7): e0130727. doi:10.1371/journal.pone.0130727en_NZ
dc.identifier.doi10.1371/journal.pone.0130727en_NZ
dc.identifier.issn1932-6203en_NZ
dc.identifier.urihttps://hdl.handle.net/10292/9025
dc.languageENGen_NZ
dc.publisherPLOS One
dc.relation.urihttp://dx.doi.org/10.1371/journal.pone.0130727
dc.rights© 2015 Myint et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
dc.rights.accessrightsOpenAccessen_NZ
dc.titleMultidrug Resistance-associated Protein 2 (MRP2) mediated transport of Oxaliplatin-derived platinum in membrane vesiclesen_NZ
dc.typeJournal Article
pubs.elements-id185884
pubs.organisational-data/AUT
pubs.organisational-data/AUT/Health & Environmental Science
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