Print Email Facebook Twitter Interactions of prostaglandin A2 with the glutathione-mediated biotransformation system Title Interactions of prostaglandin A2 with the glutathione-mediated biotransformation system Author van Iersel, M.L.P.S. Cnubben, N.H.P. Smink, N. Koeman, J.H. van Bladeren, P.J. Centraal Instituut voor Voedingsonderzoek TNO Publication year 1999 Abstract The cyclopentenone prostaglandin A2 (PGA2) is known to inhibit cell proliferation, and metabolism of this compound thus might be important in controlling its ultimate function. The glutathione-related metabolism of PGA2 was therefore investigated both with purified glutathione S-transferase P1-1 (GSTP1-1) and with IGR-39 human melanoma cells. Firstly, the irreversible inhibition of human GSTP1-1 and its mutants C47S, C101S, and C47S/C101S was studied. PGA2 appeared to inhibit GSTP1-1 mainly by binding to the cysteine 47 moiety of the enzyme. This binding was reversed by a molar excess of GSH, indicating that retro-Michael cleavage occurs. Secondly, after exposing IGR-39 human melanoma cells to PGA2, both diastereoisomers of the PGA2-glutathione conjugate are excreted into the medium, although with a clear excess of the S-form, due to its preferential formation by the GSTP1-1 present in the cells. Thirdly, the effect of PGA2 on intracellular GST activity was determined by quantification of the excreted glutathione conjugate S-(2,4-dinitrophenyl)glutathione (DNPSG) after exposure to 1-chloro-2,4-dinitrobenzene. DNPSG excretion was inhibited after incubation with 10 or 20 μM PGA2 for 1 or 4 hr, as a result of glutathione depletion, reversible GST inhibition, and covalent modification of intracellular GST. Furthermore, PGA2 also inhibited transport of DNPSG by the multidrug resistance-associated protein, an effect that was reversible and competitive. In conclusion, PGA2 modulates all three aspects of the glutathione-mediated biotransformation system, i.e. GSH levels, GSTP1-1 activity, and transport of GSH conjugates. A role for GSTP1-1 as a specific transport protein inside the cell is indicated. Copyright (C) 1999 Elsevier Science Inc. Subject NutritionCellsGlutathione S-transferasesInhibitionMetabolismProstaglandin A21 chloro 2,4 dinitrobenzeneGlutathioneGlutathione transferaseProstaglandin a2Glutathione transferase P1GSTP1 protein, humanIsoenzymeProstaglandin AProstaglandin A2BiotransformationCell functionCell metabolismCell proliferationControlled studyCytotoxicityEnzyme activityEnzyme modificationHumanHuman cellMelanoma cellPriority journalCell cultureDrug antagonismMelanomaMetabolismBiotransformationGlutathioneGlutathione S-Transferase piGlutathione TransferaseHumansIsoenzymesMelanomaProstaglandins ATumor Cells, Cultured To reference this document use: http://resolver.tudelft.nl/uuid:847cb2ef-301d-4155-9fcc-4be7e8788850 DOI https://doi.org/10.1016/s0006-2952(99)00048-9 TNO identifier 235060 ISSN 0006-2952 Source Biochemical Pharmacology, 57 (12), 1383-1390 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.