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The interactions of three heavy metal-containing compounds, cisplatin (CDDP), arsenic trioxide (As2O3), and mercury dichloride (HgCl2), with the multidrug resistance transporters MRP1 and MRP2 and the involvement of glutathione (GSH)-related processes herein were investigated. In Madin-Darby canine kidney cells stably expressing MRP1 or MRP2, viability, GSH content, calcein efflux and polarized GSH efflux were measured as a function of exposure to CDDP, As2O3 and HgCl2. In isolated Sf9-MRP1 and Sf9-MRP2 membrane vesicles, the interaction with MRP-associated ATPase activity was measured. In the latter model system adduct formation with GSH is not an issue. The data show that (1) CDDP interacts with both MRP1 and MRP2, and GSH appears to play no major role in this process, (2) As2O3 interacts with MRP1 and MRP2 in which process GSH seems to be essential, and (3) HgCl2 interacts with MRP1 and MRP2, either alone and/or as a metal-GSH complex. © 2008 Elsevier B.V. All rights reserved.

In tissue culture, protection against X irradiation by a number of cysteamine derivatives was studied and the results were compared with data obtained in mice. Compounds with a covered SH group, like WR 638, cysteamine phosphate, WR 2721 and AE AE 48527, showed practically no protection when dissolved in tissue culture medium, but developed a protective activity wehn dissolved in rat blood. Thiol measurements demonstrated that in rat blood the compounds were partly hydrolysed to thiols. C511 was also hydrolysed in culture medium and was slightly less effective than cysteamine in culture medium. Cysteamine phosphate was hydrolysed more easily than cysteamine sulphate and the protective activity in rat blood was better. WR 2721 was also partly hydrolysed in rat blood. The in vitro protection of this compound was disappointing when compared with results in vivo. Its SH form (WR 1065) also showed less protection than expected from in vivo experiments. Thus, the little protection by WR 2721 in vitro in rat blood is not only due to its incomplete conversion into its thiol. Longer incubation times and the use of rat blood as a solvent brought the protective activity of WR 1065 almost up to the level of cysteamine. This may indicate that WR 1065 penetrates the cells poorly. WR 1065 was the only compound we studied whose protective activity in vitro was improved appreciably by dissolving it in rat plasma. Chemicals/CAS: 2 (3 aminopropylamino)ethanethiol, 14653-77-1, 31098-42-7; amifostine, 20537-88-6; cystafos, 3724-89-8; cystamine, 51-85-4, 56-17-7; mercaptamine, 156-57-0, 60-23-1; thiol derivative, 13940-21-1; Amifostine, 20537-88-6; Culture Media; Cystamine, 51-85-4; Cysteamine, 60-23-1; Mercaptoethylamines; Organothiophosphorus Compounds; Radiation-Protective Agents

To study the possible interplay between glutathione metabolism of and MRP inhibition by thiol reactive compounds, the interactions of a series of α,β-unsaturated carbonyl compounds with multidrug resistance proteins 1 and 2 (MRP1/ABCC1 and MRP2/ABCC2) were studied. α,β-Unsaturated carbonyl compounds react with glutathione, and therefore either their parent compound or their intracellularly formed glutathione metabolite(s) can modulate MRP-activity. Inhibition was studied in Madin-Darby canine kidney cells stably expressing MRP1 or MRP2, and isolated Sf9-MRP1 or Sf9-MRP2 membrane vesicles. In the latter model system metabolism is not an issue. Of the series tested, three distinct groups could be discriminated based on differences in interplay of glutathione metabolism with MRP1 inhibition. Curcumin inhibited MRP1 transport only in the vesicle model pointing at inhibition by the parent compound. The glutathione conjugates of curcumin also inhibit MRP1 mediated transport, but to a much lesser extent than the parent compound curcumin. In the cellular model system, it was demonstrated that glutathione conjugation of curcumin leads to inactivation of its inhibitory potential. Demethoxycurcumin and bisdemethoxycurcumin inhibited MRP1 in both the vesicle and cellular model pointing at inhibitory potency of at least the parent compound and possibly their metabolites. A second group, including caffeic acid phenethyl ester inhibited MRP1-mediated calcein transport only in the MDCKII-MRP1 cells, and not in the vesicle model indicating that metabolism appeared a prerequisite to generate the active inhibitor. Finally cinnamaldehyde, crotonaldehyde, trans-2-hexanal, citral, and acrolein did not inhibit MRP1. For MRP2, inhibition was much less in both model systems, with the three curcuminoids being the most effective. The results of this study show the importance to study the complex interplay between MRP-inhibitors and their cellular metabolism, the latter affecting the ultimate potential of a compound for cellular MRP-inhibition. © 2005 Elsevier Inc. All rights reserved.

Wild-type strains of mice do not express CD46, a high-affinity receptor for human group B adenoviruses including type 35. Therefore, studies performed to date in mice using replication-incompetent Ad35 (rAd35) vaccine carriers may underestimate potency or result in altered vector distribution. Here, it is reported that CD46 transgenic mice (MYII-strain) express CD46 in all major organs and that it functions as a receptor for rAd35 vectors. Similar to monkeys and humans, MYII mice highly express CD46 in their lungs and kidneys and demonstrate low expression in muscle. Upon intravenous administration, rAd35 vector genomes as well as expression are detected in lungs of MYII mice, in contrast to wild-type littermates. Expression was predominantly detected in lung epithelial cells. Upon intramuscular administration, the initial level of luciferase expression is higher in MYII mice as compared with wild-type littermates, in spite of the fact that CD46 expression is low in muscle of MYII mice. The higher level of expression in muscle of MYII mice results in prolonged gene expression as assessed by CCD camera imaging for luciferase activity. Finally, a significant dose-sparing effect in MYII mice as compared with wild-type littermates on anti-SIVgag CD8+ T-cell induction following intramuscular vaccination with an rA35.SIVgag vaccine was observed. This dose-sparing effect was also observed when reinfusing dendritic cells derived from MYII mice after exposure to rAd35.SIVgag vaccine as compared with rAd35.SIVgag exposed dendritic cells from wild-type littermates. It was concluded that MYII mice represent an interesting preclinical model to evaluate potency and safety of rAd35 vectors. © 2006 SGM. Chemicals / CAS: Antigens, CD46

Digitalis-like compounds (DLCs) such as digoxin, digitoxin, and ouabain, also known as cardiac glycosides, are among the oldest pharmacological treatments for heart failure. The compounds have a narrow therapeutic window, while at the same time, DLC pharmacokinetics is prone to drug-drug interactions at the transport level. Hepatic transporters organic anion transporting polypeptide (OATP) 1B1, OATP1B3, and Na+-dependent taurocholate co-transporting polypeptide (NTCP) influence the disposition of a variety of drugs by mediating their uptake from blood into hepatocytes. The interaction of digoxin, digitoxin, and ouabain with hepatic uptake transporters has been studied before. However, here, we systematically investigated a much wider range of structurally related DLCs for their capability to inhibit or to be transported by these transporters in order to better understand the relation between the activity and chemical structure of this compound type. We studied the uptake and inhibitory potency of a series of 14 structurally related DLCs in Chinese hamster ovary cells expressing NTCP (CHO-NTCP) and human embryonic kidney cells expressing OATP1B1 and OATP1B3 (HEK-OATP1B1 and HEK-OATP1B3). The inhibitory effect of the DLCs was measured against taurocholic acid (TCA) uptake in CHO-NTCP cells and against uptake of β-estradiol 17-β-d- glucuronide (E217βG) in HEK-OATP1B1 and HEK-OATP1B3 cells. Proscillaridin A was the most effective inhibitor of NTCP-mediated TCA transport (IC50 = 22 μM), whereas digitoxin and digitoxigenin were the most potent inhibitors of OATP1B1 and OAPTP1B3, with IC50 values of 14.2 and 36 μM, respectively. Additionally, we found that the sugar moiety and hydroxyl groups of the DLCs play different roles in their interaction with NTCP, OATP1B1, and OATP1B3. The sugar moiety decreases the inhibition of NTCP and OATP1B3 transport activity, whereas it enhances the inhibitory potency against OATP1B1. Moreover, the hydroxyl group at position 12 reinforces the inhibition of NTCP but decreases the inhibition of OATP1B1 and OATP1B3. To investigate whether DLCs can be translocated, we quantified their uptake in transporter-expressing cells by LC-MS. We demonstrated that convallatoxin, ouabain, dihydroouabain, and ouabagenin are substrates of OATP1B3. No transport was observed for the other compounds in any of the studied transporters. In summary, this work provides a step toward an improved understanding of the interaction of DLCs with three major hepatic uptake transporters. Ultimately, this can be of use in the development of DLCs that are less prone to transporter-mediated drug-drug interactions. © 2014 American Chemical Society. Chemicals/CAS: convallatoxin, 508-75-8; cymarin, 508-77-0; digitoxigenin, 143-62-4, 25495-72-1; digitoxin, 71-63-6; digoxigenin, 1672-46-4; digoxin, 20830-75-5, 57285-89-9; dihydroouabain, 1183-35-3; estradiol 17 glucuronide, 1806-98-0; ouabagenin, 508-52-1; ouabain, 11018-89-6, 630-60-4; peruvoside, 1182-87-2; proscillaridin, 466-06-8; strophanthidin, 66-28-4; taurocholic acid, 145-42-6, 59005-70-8, 81-24-3 Manufacturers: Sigma, Netherlands