• MeSH
• biologický transport MeSH
• buněčná membrána MeSH
• mnohočetná léková rezistence MeSH
• P-glykoprotein farmakologie   genetika   chemie   MeSH
• polymorfismus genetický MeSH

• MeSH
• adenosintrifosfatasy MeSH
• membránové glykoproteiny MeSH
• mnohočetná léková rezistence MeSH
• P-glykoproteiny fyziologie   genetika   chemie   MeSH

Recently, it has been suggested that imatinib (IM) and nilotinib (NIL) could be studied beyond their original application, as inhibitors of the drug efflux pump ABCB1 (P-glycoprotein, MDR1). Since the reversal of ABCB1-mediated resistance has never been successfully demonstrated in the clinic, we addressed the question of whether IM and NIL may actually serve as efficient inhibitors of ABCB1. Here we define an efficient inhibitor as a compound that achieves full (90-100%) reversal of drug efflux at a concentration that does not exhibit significant off-target toxicity in vitro. In this study, human leukemia K562 cells expressing various levels of ABCB1 were used. We observed that cells expressing higher ABCB1 levels required higher concentrations of IM and NIL to achieve full reversal of drug efflux. Among the well-known ABCB1 inhibitors, a similar effect was found for cyclosporin A (CsA) but not for zosuquidar. IM was efficient only in cells with the low and moderate ABCB1 expression at high concentrations that were cytotoxic in the absence of Bcr-Abl. In contrast, NIL was as efficient an inhibitor of ABCB1 as CsA. Low and moderate expression levels of ABCB1 could be efficiently inhibited by NIL concentrations without cytotoxic effects in the absence of Bcr-Abl. However, high expression levels of ABCB1 required higher NIL concentrations with off-target cytotoxic effects. In conclusion, application of NIL, but not of IM, in clinics is promising, however, only in cells with low ABCB1 expression levels. We hypothesize that some patients may benefit from an inhibitor exhibiting an ABCB1 expression-dependent effect.

• MeSH
• imatinib mesylát farmakologie   MeSH
• lidé MeSH
• nádorové buňky kultivované MeSH
• P-glykoproteiny antagonisté a inhibitory   metabolismus   MeSH
• proliferace buněk účinky léků   MeSH
• pyrimidiny farmakologie   MeSH
• viabilita buněk účinky léků   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

Arabidopsis ATP-binding cassette B4 (ABCB4) is a root-localised auxin efflux transporter with reported auxin uptake activity in low auxin concentrations. Results reported here demonstrate that ABCB4 is a substrate-activated regulator of cellular auxin levels. The contribution of ABCB4 to shootward auxin movement at the root apex increases with auxin concentration, but in root hair elongation assays ABCB4-mediated uptake is evident at low concentrations as well. Uptake kinetics of ABCB4 heterologously expressed in Schizosaccharomyces pombe differed from the saturation kinetics of AUX1 as uptake converted to efflux at threshold indole-3-acetic acid (IAA) concentrations. The concentration dependence of ABCB4 appears to be a direct effect on transporter activity, as ABCB4 expression and ABCB4 plasma membrane (PM) localisation at the root apex are relatively insensitive to changes in auxin concentration. However, PM localization of ABCB4 decreases with 1-naphthylphthalamic acid (NPA) treatment. Unlike other plant ABCBs studied to date, and consistent with decreased detergent solubility, ABCB4(pro) :ABCB4-GFP is partially internalised in all cell types by 0.05% DMSO, but not 0.1% ethanol. In trichoblasts, ABCB4(pro) :ABCB4-GFP PM signals are reduced by >200 nm IAA and 2,4-dichlorophenoxyacetic acid (2,4-D). In heterologous systems and in planta, ABCB4 transports benzoic acid with weak affinity, but not the oxidative catabolism products 2-oxindole-3-acetic-acid and 2-oxindole-3-acetyl-β-D-glucose. ABCB4 mediates uptake, but not efflux, of the synthetic auxin 2,4-D in cells lacking AUX1 activity. Results presented here suggest that 2,4-D is a non-competitive inhibitor of IAA transport by ABCB4 and indicate that ABCB4 is a target of 2,4-D herbicidal activity.

• MeSH
• ABC transportéry genetika   metabolismus   MeSH
• Arabidopsis cytologie   účinky léků   genetika   fyziologie   MeSH
• biologický transport MeSH
• buněčná membrána metabolismus   MeSH
• epidermis rostlin cytologie   metabolismus   MeSH
• indoly metabolismus   MeSH
• kořeny rostlin cytologie   metabolismus   MeSH
• kyselina 2,4-dichlorfenoxyoctová metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• mutace MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• Schizosaccharomyces genetika   metabolismus   MeSH
• signální transdukce fyziologie   MeSH
• tabák genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Brivanib, a promising tyrosine kinase inhibitor, is currently undergoing advanced stages of clinical evaluation for solid tumor therapy. In this work, we investigated possible interactions of this novel drug candidate with ABC drug efflux transporters and cytochrome P450 (CYP450) drug-metabolizing enzymes that participate in cancer multidrug resistance (MDR) and pharmacokinetic drug-drug interactions (DDIs). First, in accumulation experiments with various model substrates, we identified brivanib as an inhibitor of the ABCB1, ABCG2, and ABCC1 transporters. However, in subsequent combination studies employing 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide proliferation assays in both Madin-Darby canine kidney II (MDCKII) and A431 cellular models, only ABCG2 inhibition was revealed to be able to synergistically potentiate mitoxantrone effects. Advantageous to its possible use as MDR antagonist, brivanib's chemosensitizing properties were not impaired by activity of any of the MDR-associated ABC transporters, as observed in comparative viability assay in the MDCKII cell sublines. In incubation experiments with eight recombinant CYP450s, we found that brivanib potently inhibited CYP2C subfamily members and the CYP2B6 isoform. Finally, in induction studies, we demonstrated that brivanib upregulated ABCB1 and CYP1A2 messenger RNA levels in systemic cell models, although this interaction was not significantly manifested at a functional level. In conclusion, brivanib exhibits potential to cause clinically relevant pharmacokinetic DDIs and act as a modulator of ABCG2-mediated MDR. Our findings might be used as an important background for subsequent in vivo investigations and pave the way for the safe and effective use of brivanib in oncological patients.

• MeSH
• ABC transportér z rodiny G, člen 2 antagonisté a inhibitory   MeSH
• alanin analogy a deriváty   farmakologie   MeSH
• biotransformace účinky léků   MeSH
• buněčné linie MeSH
• buňky MDCK MeSH
• chemorezistence účinky léků   MeSH
• inhibitory cytochromu P450 farmakologie   MeSH
• lékové interakce fyziologie   MeSH
• lidé MeSH
• mnohočetná léková rezistence účinky léků   MeSH
• nádorové proteiny antagonisté a inhibitory   MeSH
• P-glykoproteiny metabolismus   MeSH
• psi MeSH
• systém (enzymů) cytochromů P-450 metabolismus   MeSH
• triaziny farmakologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• psi MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

• MeSH
• antitumorózní látky MeSH
• biologický transport MeSH
• buněčné linie MeSH
• finanční podpora výzkumu jako téma MeSH
• fluorescenční barviva MeSH
• lidé MeSH
• mnohočetná léková rezistence MeSH
• P-glykoprotein antagonisté a inhibitory   MeSH
• průtoková cytometrie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• přehledy MeSH
• srovnávací studie MeSH

Entrectinib is a new tyrosine kinase inhibitor that was recently approved for the treatment of ROS1-positive metastatic non-small cell lung cancer (NSCLC). In this study, we aimed to characterize its potential to act as a modulator of pharmacokinetic cytostatic resistance and perpetrator of drug interactions. In accumulation studies, entrectinib exhibited potent inhibition of ABCB1, while only moderate interaction was recorded for ABCG2 and ABCC1 efflux transporters. Furthermore, incubation assays revealed the potential of this drug to inhibit various recombinant cytochrome P450 enzymes, which can be ranked according to inhibitory affinities as follows: CYP2C8 ≈ CYP3A4 > CYP2C9 > CYP2C19 ≈ CYP3A5 > CYP2D6 > CYP2B6 > CYP1A2. Additionally, in silico docking analysis confirmed entrectinib's interactions with ABCB1 and CYP3A4 and resolved their possible molecular background. In subsequent drug combination experiments, we demonstrated the ability of entrectinib to synergize with daunorubicin in various ABCB1-expressing cellular models. Moreover, the comparative proliferation study results suggested that the anticancer efficacy of entrectinib is not affected by the functional presence of tested ABC transporters. In contrast to ABCB1-related data, no resistance reversal effect was recorded for the combination with docetaxel in HepG2-CYP3A4 cells. In the final experimental set, we observed no significant changes in ABCB1, ABCG2, ABCC1 or CYP3A4 gene expression in NSCLC cells exposed to entrectinib. In summary, our work indicates that entrectinib may be a perpetrator of clinically relevant pharmacokinetic drug interactions and modulator of ABCB1-mediated resistance. Our in vitro results might provide a valuable foundation for future clinical investigations.

• MeSH
• benzamidy farmakologie   MeSH
• buňky A549 MeSH
• buňky Hep G2 MeSH
• buňky MDCK MeSH
• chemorezistence účinky léků   fyziologie   MeSH
• cytochrom P-450 CYP3A * chemie   metabolismus   MeSH
• cytostatické látky farmakologie   MeSH
• indazoly farmakologie   MeSH
• inhibitory proteinkinas farmakologie   MeSH
• lidé MeSH
• mnohočetná léková rezistence účinky léků   fyziologie   MeSH
• nádorové buněčné linie MeSH
• P-glykoproteiny antagonisté a inhibitory   chemie   metabolismus   MeSH
• psi MeSH
• sekundární struktura proteinů MeSH
• simulace molekulového dockingu metody   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• psi MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Efluxní pumpy, které jsou schopny odčerpávat z bakteriální buňky aktivně antibiotika, můžeme jmenovat jako jeden z možných mechanizmů vzniku antimikrobiální rezistence. Mezi nejvýznamnější skupinu efluxních pump, schopných vyplavovat i více typů antibiotik, řadíme RND (resistance - nodulation - division) pumpy. Jedná se o tři na sebe navazující proteiny, procházející napříč buněčnou stěnou bakterie, umožňující vypuzení látky přímo ven z bakteriální buňky. Nejvíce prostudovanými jsou efluxní pumpy AcrAB-TolC u Escherichia coli a MexAB-OprM u Pseudomonas aeruginosa. Efluxní pumpy jsou schopny odčerpávat i jiné než antibakteriální látky, např. dezinfekční prostředky, čímž snižují jejich účinek. Jednou z možností, jak efluxní pumpy inaktivovat, je použiti tzv. inhibitorů efluxních pump (efflux pump inhibitor = EPI). Mezi potenciální inhibitory testované in vitro můžeme řadit např. phenylalanyl arginyl β-naphtylamide (PAβN), carbonyl cyanide m-chlorophenylhydrazone (CCCP) nebo látky z řad fenothiazinů.

Efflux pumps capable of actively draining antibiotic agents from bacterial cells may be considered one of potential mechanisms of the development of antimicrobial resistance. The most important group of efflux pumps capable of removing several types of antibiotics include RND (resistance - nodulation - division) pumps. These are three proteins that cross the bacterial cell wall, allowing direct expulsion of the agent out from the bacterial cell. The most investigated efflux pumps are the AcrAB-TolC system in Escherichia coli and the MexAB-OprM system in Pseudomonas aeruginosa. Moreover, efflux pumps are able to export other than antibacterial agents such as disinfectants, thus decreasing their effectiveness. One potential approach to inactivation of an efflux pump is to use the so-called efflux pump inhibitors (EPIs). Potential inhibitors tested in vitro involve, for example, phenylalanyl-arginyl-β-naphthylamide (PAβN), carbonyl cyanide m-chlorophenylhydrazone (CCCP) or agents of the phenothiazine class.

• Klíčová slova
• inhibitory efluxních pump,
• MeSH
• aktivní transport fyziologie   účinky léků   MeSH
• antibakteriální látky * farmakologie   MeSH
• Bacteria účinky léků   MeSH
• bakteriální léková rezistence * fyziologie   MeSH
• bakteriální proteiny * antagonisté a inhibitory   fyziologie   metabolismus   MeSH
• beta-laktamasy farmakologie   MeSH
• buněčná membrána metabolismus   MeSH
• dezinficiencia farmakologie   MeSH
• fluorochinolony farmakologie   MeSH
• lidé MeSH
• membránové proteiny * fyziologie   metabolismus   MeSH
• membránové transportní proteiny fyziologie   MeSH
• proteiny vnější bakteriální membrány fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• práce podpořená grantem MeSH
• přehledy MeSH

Alzheimer's disease (AD) is a devastating neurological disorder characterized by the pathological accumulation of macromolecular Aβ and tau leading to neuronal death. Drugs approved to treat AD may ameliorate disease symptoms, however, no curative treatment exists. Aβ peptides were discovered to be substrates of adenosine triphosphate-(ATP)-binding cassette (ABC) transporters. Activators of these membrane-bound efflux proteins that promote binding and/or translocation of Aβ could revolutionize AD medicine. The knowledge about ABC transporter activators is very scarce, however, the few molecules that were reported contain substructural features of multitarget (pan-)ABC transporter inhibitors. A cutting-edge strategy to obtain new drug candidates is to explore and potentially exploit the recently proposed multitarget binding site of pan-ABC transporter inhibitors as anchor point for the development of innovative activators to promote Aβ clearance from the brain. Molecular associations between functional bioactivities and physicochemical properties of small-molecules are key to understand these processes. This study provides an analysis of a recently reported unique multitarget dataset for the correlation between multitarget bioactivity and physicochemistry. Six novel pan-ABC transporter inhibitors were validated containing substructural features of ABC transporter activators, which underpins the relevance of the multitarget binding site for the targeted development of novel AD diagnostics and therapeutics.

• MeSH
• ABC transportér z rodiny G, člen 2 metabolismus   MeSH
• ABC transportéry metabolismus   MeSH
• Alzheimerova nemoc * farmakoterapie   metabolismus   MeSH
• biologický transport MeSH
• chemické jevy MeSH
• lidé MeSH
• mozek metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

PURPOSE: S-(4-Nitrobenzyl)-6-thioinosine (NBMPR) is routinely used at concentrations of 0.10 μM and 0.10 mM to specifically inhibit transport of nucleosides mediated by equilibrative nucleoside transporters 1 (ENT1) and 2 (ENT2), respectively. We recently showed that NBMPR (0.10 mM) might also inhibit placental active efflux of [3H]zidovudine and [3H]tenofovir disoproxil fumarate. Here we test the hypothesis that NBMPR abolishes the activity of P-glycoprotein (ABCB1) and/or breast cancer resistance protein (ABCG2). METHODS: We performed accumulation assays with Hoechst 33342 (a model dual substrate of ABCB1 and ABCG2) and bi-directional transport studies with the ABCG2 substrate [3H]glyburide in transduced MDCKII cells, accumulation studies in choriocarcinoma-derived BeWo cells, and in situ dual perfusions of rat term placenta with glyburide. RESULTS: NBMPR inhibited Hoechst 33342 accumulation in MDCKII-ABCG2 cells (IC50 = 53 μM) but not in MDCKII-ABCB1 and MDCKII-parental cells. NBMPR (0.10 mM) also inhibited bi-directional [3H]glyburide transport across monolayers of MDCKII-ABCG2 cells and blocked ABCG2-mediated [3H]glyburide efflux by rat term placenta in situ. CONCLUSION: NBMPR at a concentration of 0.10 mM abolishes ABCG2 activity. Researchers using NBMPR to evaluate the effect of ENTs on pharmacokinetics must therefore interpret their results carefully if studying compounds that are substrates of both ENTs and ABCG2.

• MeSH
• ABC transportér z rodiny G, člen 2 antagonisté a inhibitory   metabolismus   MeSH
• antivirové látky metabolismus   farmakokinetika   MeSH
• biologický transport účinky léků   MeSH
• buněčné linie MeSH
• buňky MDCK MeSH
• krysa rodu rattus MeSH
• lidé MeSH
• nádorové proteiny antagonisté a inhibitory   metabolismus   MeSH
• P-glykoproteiny antagonisté a inhibitory   metabolismus   MeSH
• placenta účinky léků   metabolismus   MeSH
• potkani Wistar MeSH
• psi MeSH
• těhotenství MeSH
• thioinosin analogy a deriváty   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• lidé MeSH
• psi MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH