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Journal of Pharmacological Sciences 2010This study was conducted to determine the rate of P-glycoprotein (P-gp)-mediated efflux of digoxin analogues and metabolites and to assess the effects of macrolide...
This study was conducted to determine the rate of P-glycoprotein (P-gp)-mediated efflux of digoxin analogues and metabolites and to assess the effects of macrolide antibiotics on this efflux. Bidirectional transport studies were conducted using our Caco-2 sub clone with high P-gp expression (CLEFF9). HPLC methods were employed to measure drug transport. All digoxin metabolites were P-gp substrates, although digoxin had the greatest efflux ratio. Erythromycin had no effect on the transport of digoxin, maintaining a basolateral to apical efflux ratio of 14.8, although it did reduce the efflux ratio of dihydrodigoxin and digoxigenin by 34% and 43%, respectively. Azithromycin also had little effect on the transport of digoxin or any of its metabolites. In contrast, clarithromycin and roxithromycin almost eliminated basolateral targeted efflux. Using paclitaxel as a known P-gp substrate, erythromycin demonstrated only partial P-gp inhibitory capacity, maintaining an efflux ratio over 100. In contrast, clarithromycin and roxithromycin were 10-fold greater P-gp inhibitors. Clarithromycin and roxithromycin are likely to exhibit drug interactions with digoxin via inhibition of efflux mechanisms. Azithromycin appears to have little influence on P-gp-mediated digoxin absorption or excretion and would be the safest macrolide to use concurrently with oral digoxin.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Anti-Bacterial Agents; Caco-2 Cells; Chromatography, High Pressure Liquid; Digoxin; Humans; Limit of Detection; Macrolides
PubMed: 20724802
DOI: 10.1254/jphs.10109fp -
Cells Oct 2019P-glycoprotein (P-gp) is an important determinant of multidrug resistance (MDR) because its overexpression is associated with increased efflux of various established...
P-glycoprotein (P-gp) is an important determinant of multidrug resistance (MDR) because its overexpression is associated with increased efflux of various established chemotherapy drugs in many clinically resistant and refractory tumors. This leads to insufficient therapeutic targeting of tumor populations, representing a major drawback of cancer chemotherapy. Therefore, P-gp is a target for pharmacological inhibitors to overcome MDR. In the present study, we utilized machine learning strategies to establish a model for P-gp modulators to predict whether a given compound would behave as substrate or inhibitor of P-gp. Random forest feature selection algorithm-based leave-one-out random sampling was used. Testing the model with an external validation set revealed high performance scores. A P-gp modulator list of compounds from the ChEMBL database was used to test the performance, and predictions from both substrate and inhibitor classes were selected for the last step of validation with molecular docking. Predicted substrates revealed similar docking poses than that of doxorubicin, and predicted inhibitors revealed similar docking poses than that of the known P-gp inhibitor elacridar, implying the validity of the predictions. We conclude that the machine-learning approach introduced in this investigation may serve as a tool for the rapid detection of P-gp substrates and inhibitors in large chemical libraries.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Artificial Intelligence; Drug Discovery; Humans; Machine Learning; Molecular Docking Simulation; Software
PubMed: 31640190
DOI: 10.3390/cells8101286 -
Drug Metabolism and Disposition: the... Apr 2014P-glycoprotein (P-gp) is a key player in the multidrug-resistant phenotype in cancer. The protein confers resistance by mediating the ATP-dependent efflux of an... (Review)
Review
P-glycoprotein (P-gp) is a key player in the multidrug-resistant phenotype in cancer. The protein confers resistance by mediating the ATP-dependent efflux of an astonishing array of anticancer drugs. Its broad specificity has been the subject of numerous attempts to inhibit the protein and restore the efficacy of anticancer drugs. The general strategy has been to develop compounds that either compete with anticancer drugs for transport or act as direct inhibitors of P-gp. Despite considerable in vitro success, there are no compounds currently available to "block" P-gp-mediated resistance in the clinic. The failure may be attributed to toxicity, adverse drug interaction, and numerous pharmacokinetic issues. This review provides a description of several alternative approaches to overcome the activity of P-gp in drug-resistant cells. These include 1) drugs that specifically target resistant cells, 2) novel nanotechnologies to provide high-dose, targeted delivery of anticancer drugs, 3) compounds that interfere with nongenomic transfer of resistance, and 4) approaches to reduce the expression of P-gp within tumors. Such approaches have been developed through the pursuit of greater understanding of resistance mediators such as P-gp, and they show considerable potential for further application.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Antineoplastic Agents; Biological Transport; Drug Delivery Systems; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Neoplasms; Substrate Specificity
PubMed: 24492893
DOI: 10.1124/dmd.113.056176 -
The Journal of Biological Chemistry Nov 1996Plasma membrane P-glycoprotein is known as an ATP-dependent drug efflux pump that confers multidrug resistance to tumor cells. None of the reported purification...
Plasma membrane P-glycoprotein is known as an ATP-dependent drug efflux pump that confers multidrug resistance to tumor cells. None of the reported purification procedures worked properly for our P-glycoprotein-overproducing cell lines, i.e. murine lymphoid leukemia P388/ADR25, rat hepatoma AS30-D/COL10, and human lymphoblastic leukemia CEM/VLB5 cells. We have thus developed a general procedure for efficient purification of P-glycoprotein by combining solubilization with sodium dodecyl sulfate and chromatography on ceramic hydroxyapatite. This procedure was successful for the three cell lines and yielded 70% of the P-glycoprotein present in the starting plasma membranes with more than 99% purity. After exchanging sodium dodecyl sulfate into dodecyl maltoside and reconstitution into liposomes, purified P-glycoprotein exhibited a specific ATPase activity of about 200 nmol/min/mg, which was very similar to that obtained for P-glycoprotein solubilized and purified with 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid. This ATPase activity was sensitive to orthovanadate inhibition and stimulated by verapamil and other drugs. More importantly, drug transport properties of the reconstituted P-glycoprotein were comparable with those of P-glycoprotein embedded in plasma membranes. Since it is virtually devoid of lipids, this preparation is suitable for both functional and structural investigations.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Adenosine Triphosphatases; Adenosine Triphosphate; Animals; Biological Transport; Cell Membrane; Chromatography, High Pressure Liquid; Electrophoresis, Polyacrylamide Gel; Humans; Mice; Protein Conformation; Rats; Structure-Activity Relationship; Tritium; Tumor Cells, Cultured; Vinblastine
PubMed: 8910534
DOI: 10.1074/jbc.271.46.28875 -
Journal of Cellular and Molecular... Apr 2018LysoTracker and MitoTracker Red are fluorescent probes widely used for viable cell staining of lysosomes and mitochondria, respectively. They are utilized to study...
LysoTracker and MitoTracker Red are fluorescent probes widely used for viable cell staining of lysosomes and mitochondria, respectively. They are utilized to study organelle localization and their resident proteins, assess organelle functionality and quantification of organelle numbers. The ATP-driven efflux transporter P-glycoprotein (P-gp) is expressed in normal and malignant tissues and extrudes structurally distinct endogenous and exogenous cytotoxic compounds. Thus, once aromatic hydrophobic compounds such as the above-mentioned fluorescent probes are recognized as transport substrates, efflux pumps including P-gp may abolish their ability to reach their cellular target organelles. Herein, we show that LysoTracker and MitoTracker Red are expelled from P-gp-overexpressing cancer cells, thus hindering their ability to fluorescently mark target organelles. We further demonstrate that tariquidar, a potent P-gp transport inhibitor, restores LysoTracker and MitoTracker Red cell entry. We conclude that LysoTracker and MitoTracker Red are P-gp transport substrates, and therefore, P-gp expression must be taken into consideration prior to cellular applications using these probes. Importantly, as MitoTracker was a superior P-gp substrate than LysoTracker Red, we discuss the implications for the future design of chemotherapeutics evading cancer multidrug resistance. Furthermore, restoration of MitoTracker Red fluorescence in P-gp-overexpressing cells may facilitate the identification of potent P-gp transport inhibitors (i.e. chemosensitizers).
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Amines; Antineoplastic Agents; Cell Line, Tumor; Cell Membrane; Drug Design; Drug Resistance, Neoplasm; Humans; Models, Biological; Organic Chemicals; Protein Transport
PubMed: 29377455
DOI: 10.1111/jcmm.13485 -
The AAPS Journal Mar 2017P-glycoprotein (Pgp) is an ATP-binding cassette (ABC) transporter that plays a major role in cardiovascular drug disposition by effluxing a chemically and structurally... (Review)
Review
P-glycoprotein (Pgp) is an ATP-binding cassette (ABC) transporter that plays a major role in cardiovascular drug disposition by effluxing a chemically and structurally diverse range of cardiovascular therapeutics. Unfortunately, drug-drug interactions (DDIs) with the transporter have become a major roadblock to effective cardiovascular drug administration because they can cause adverse drug reactions (ADRs) or reduce the efficacy of drugs. Cardiovascular ion channel inhibitors are particularly susceptible to DDIs and ADRs with Pgp because they often have low therapeutic indexes and are commonly coadministered with other drugs that are also Pgp substrates. DDIs from cardiovascular ion channel inhibitors with the transporter occur because of inhibition or induction of the transporter and the transporter's tissue and cellular localization. Inhibiting Pgp can increase absorption and reduce excretion of drugs, leading to elevated drug plasma concentrations and drug toxicity. In contrast, inducing Pgp can have the opposite effect by reducing the drug plasma concentration and its efficacy. A number of in vitro and in vivo studies have already demonstrated DDIs from several cardiovascular ion channel inhibitors with human Pgp and its animal analogs, including verapamil, digoxin, and amiodarone. In this review, Pgp-mediated DDIs and their effects on pharmacokinetics for different categories of cardiovascular ion channel inhibitors are discussed. This information is essential for improving pharmacokinetic predictions of cardiovascular therapeutics, for safer cardiovascular drug administration and for mitigating ADRs emanating from Pgp.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Biological Transport; Cardiovascular Agents; Drug Interactions; Humans; Ion Channels
PubMed: 28028729
DOI: 10.1208/s12248-016-0023-y -
International Journal of Molecular... Apr 2019Overcoming P-glycoprotein (P-gp) efflux is a strategy to improve the absorption and pharmacokinetics of its substrate drugs. Berberine inhibits P-gp and thereby...
Overcoming P-glycoprotein (P-gp) efflux is a strategy to improve the absorption and pharmacokinetics of its substrate drugs. Berberine inhibits P-gp and thereby increases the bioavailability of the P-gp substrate digoxin in rodents. However, the effects of berberine on P-gp in chickens are still unclear. Here, we studied the role of berberine in modulating broilers P-gp expression and function through both in situ and in vitro models. In addition, molecular docking was applied to analyze the interactions of berberine with P-gp as well as with chicken xenobiotic receptor (CXR). The results showed that the mRNA expression levels of chicken P-gp and CXR decreased in the ileum following exposure to berberine. The absorption rate constant of rhodamine 123 increased after berberine treatment, as detected using an in situ single-pass intestinal perfusion model. Efflux ratios of P-gp substrates (tilmicosin, ciprofloxacin, clindamycin, ampicillin, and enrofloxacin) decreased and the apparent permeability coefficients increased after co-incubation with berberine in MDCK-chAbcb1 cell models. Bidirectional assay results showed that berberine could be transported by chicken P-gp with a transport ratio of 4.20, and this was attenuated by verapamil (an inhibitor of P-gp), which resulted in a ratio of 1.13. Molecular docking revealed that berberine could form favorable interactions with the binding pockets of both CXR and P-gp, with docking scores of -7.8 and -9.5 kcal/mol, respectively. These results indicate that berberine is a substrate of chicken P-gp and down-regulates P-gp expression in chicken tissues, thereby increasing the absorption of P-gp substrates. Our findings suggest that berberine increases the bioavailability of other drugs and that drug-drug interactions should be considered when it is co-administered with other P-gp substrates with narrow therapeutic windows.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Avian Proteins; Berberine; Chickens; Dogs; Gene Expression Regulation; Madin Darby Canine Kidney Cells; Models, Molecular; Protein Conformation; RNA, Messenger; Receptors, Cytoplasmic and Nuclear; Structure-Activity Relationship
PubMed: 31013627
DOI: 10.3390/ijms20081966 -
Biochemical Pharmacology Jan 2012Ivermectin is widely used in human and veterinary medicine for the control of helminth infections. Ivermectin is known to interact with P-glycoprotein (P-gp/MDR1), being... (Comparative Study)
Comparative Study
Ivermectin is widely used in human and veterinary medicine for the control of helminth infections. Ivermectin is known to interact with P-glycoprotein (P-gp/MDR1), being a good substrate and a potent inhibitor, however, the influence of ivermectin on the expression of the transporter has not been investigated. Expression of P-glycoprotein was investigated in cultured mouse hepatocytes acutely exposed to ivermectin. The two P-glycoprotein murine isoforms, Mdr1a and Mdr1b, mRNA levels were assessed by real-time RT-PCR. Ivermectin induced a clear time- and concentration-dependent up-regulation of Mdr1a and Mdr1b mRNA levels (as early as a 12-h exposure and up to 2.5-fold at 10μM). Moreover, ivermectin-treated cells displayed enhanced cellular efflux of the P-glycoprotein substrate calcein that was inhibited by the P-glycoprotein blocker valspodar, providing evidence that the ivermectin-induced P-glycoprotein was functional. The mechanisms underlying these effects were investigated. Ivermectin-mediated Mdr1 mRNA induction was independent of the two nuclear receptors CAR and PXR, which are known to be involved in drug transporters regulation. Moreover, by using reporter cell lines that detects specific ligand-activated transcription factors, we showed that ivermectin did not displayed CAR, PXR or AhR ligand activities. However, studies with actinomycin D revealed that the half-life of Mdr1a and Mdr1b mRNA were significantly prolonged by two-fold in ivermectin-treated cells suggesting a post-transcriptional mode of ivermectin regulation. This study demonstrates for the first time that ivermectin induces P-glycoprotein overexpression through post-transcriptional mRNA stabilization, thus offering insight into the mechanism of reduced therapeutic efficacy and development of ivermectin-resistant parasites.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Cell Line; Cell Line, Transformed; Dose-Response Relationship, Drug; Gene Expression Regulation; Hepatocytes; Ivermectin; Mice; RNA Stability; RNA, Messenger; Substrate Specificity
PubMed: 22024132
DOI: 10.1016/j.bcp.2011.10.010 -
Current Medicinal Chemistry 2019Dual-targeting in cancer treatment by a single drug is an unconventional approach in relation to drug combinations. The rationale for the development of dualtargeting... (Review)
Review
BACKGROUND
Dual-targeting in cancer treatment by a single drug is an unconventional approach in relation to drug combinations. The rationale for the development of dualtargeting agents is to overcome incomplete efficacy and drug resistance frequently present when applying individual targeting agents. Consequently, -a more favorable outcome of cancer treatment is expected with dual-targeting strategies.
METHODS
We reviewed the literature, concentrating on the association between clinically relevant and/or novel dual inhibitors with the potential to modulate multidrug resistant phenotype of cancer cells, particularly the activity of P-glycoprotein. A balanced analysis of content was performed to emphasize the most important findings and optimize the structure of this review.
RESULTS
Two-hundred and forty-five papers were included in the review. The introductory part was interpreted by 9 papers. Tyrosine kinase inhibitors' role in the inhibition of Pglycoprotein and chemosensitization was illustrated by 87 papers. The contribution of naturalbased compounds in overcoming multidrug resistance was reviewed using 92 papers, while specific dual inhibitors acting against microtubule assembling and/or topoisomerases were described with 55 papers. Eleven papers gave an insight into a novel and less explored approach with hybrid drugs. Their influence on P-glycoprotein and multidrug resistance was also evaluated.
CONCLUSION
These findings bring into focus rational anticancer strategies with dual-targeting agents. Most evaluated synthetic and natural drugs showed a great potential in chemosensitization. Further steps in this direction are needed for the optimization of anticancer treatment.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Antineoplastic Agents; Drug Resistance, Neoplasm; Humans; Neoplasms; Polyphenols; Protein Kinase Inhibitors; Topoisomerase Inhibitors; Tubulin Modulators
PubMed: 29874992
DOI: 10.2174/0929867325666180607094856 -
Methods and Findings in Experimental... Oct 2002Active efflux of many therapeutics and other xenobiotics from cells and tissues by P-glycoprotein (P-gp) can cause dramatic effects on bioavailability. This expulsion of... (Review)
Review
Active efflux of many therapeutics and other xenobiotics from cells and tissues by P-glycoprotein (P-gp) can cause dramatic effects on bioavailability. This expulsion of compounds from cells is known as a major form of multiple drug resistance (MDR). Often a significant barrier to oral absorption at the intestine, P-gp also protects the liver, brain, placenta, testes, adrenal gland and other tissues from cytotoxic insult. Due to the wide tolerance of substrate recognition, P-gp can often be the mechanism for significant pharmacokinetic drug interactions when two or more drugs are competing for the P-gp transport site. P-gp levels are also inducible and can be even further elavated in cancer cells, thus contributing to the confounding pleiotropic resistance to chemotherapy and poor treatment prognosis. Consequently, a broad scope of research over 20 years has led to the evaluation of co-therapies intended to augment chemotherapy by inhibiting P-gp. This review includes a list of the currently known P-gp inhibiting adjuvant candidates described in the literature, with associated references and summary data. The summary catalogue of P-gp modulators illustrates the ardent pursuit to overcome this form of therapy resistance and gives examples of clinical success and failure.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Absorption; Adjuvants, Pharmaceutic; Animals; Antineoplastic Agents; Chemotherapy, Adjuvant; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Humans; Tissue Distribution
PubMed: 12500430
DOI: 10.1358/mf.2002.24.8.705071