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Food and Chemical Toxicology : An... Dec 2020The drug transporter P-glycoprotein (P-gp) is often investigated in drug-interaction studies because the activity is modulated by a wide variety of xenobiotics including...
The drug transporter P-glycoprotein (P-gp) is often investigated in drug-interaction studies because the activity is modulated by a wide variety of xenobiotics including drugs, herbal products, and food components. In this study, we tested six common arylsulfonate food dyes-allura red, carmoisine, ponceau 4R, quinolone yellow, sunset yellow, and tartrazine-as activators and inhibitors of P-gp activity in vitro. The dyes were studied as P-gp activators by measuring ATPase activity in P-gp-expressing membranes. Compared to verapamil, a known activator of P-gp, the six food dyes showed no stimulatory activity. The potential for these six food dyes to act as P-gp inhibitors was tested in an intracellular efflux assay with P-gp-expressing cells. Compared to GF120918, a known P-gp inhibitor, there was no inhibitory activity for these six food dyes. The six food dyes tested do not interact with P-gp in vitro and, therefore, are unlikely cause clinical drug-food dye interactions. Further investigation is necessary to determine whether these food dyes could interact with other drug transporters.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Adenosine Triphosphatases; Biological Transport; Drug Interactions; Food Coloring Agents; Food-Drug Interactions; Humans; Verapamil
PubMed: 33011351
DOI: 10.1016/j.fct.2020.111785 -
Frontiers in Oncology 2020P-glycoprotein or multidrug resistance protein (MDR1) is an adenosine triphosphate (ATP) binding cassette transporter (ABCB1) intensely investigated because it is an... (Review)
Review
P-glycoprotein or multidrug resistance protein (MDR1) is an adenosine triphosphate (ATP) binding cassette transporter (ABCB1) intensely investigated because it is an obstacle to successful pharmacotherapy of cancers. P-glycoprotein prevents cellular uptake of a large number of structurally and functionally diverse compounds, including most cancer therapeutics and in this way causes multidrug resistance (MDR). To overcome MDR, and thus improve cancer treatment, an understanding of P-glycoprotein inhibition at the molecular level is required. With this goal in mind, we propose rules that predict whether a compound is a modulator, substrate, inhibitor, or inducer of P-glycoprotein. This new set of rules is derived from a quantitative analysis of the drug binding and transport properties of P-glycoprotein. We further discuss the role of P-glycoprotein in immune surveillance and cell metabolism. Finally, the predictive power of the proposed rules is demonstrated with a set of FDA approved drugs which have been repurposed for cancer therapy.
PubMed: 33194688
DOI: 10.3389/fonc.2020.576559 -
Heliyon Jun 2022The multidrug resistance phenomenon presents a major threat to the pharmaceutical industry. This resistance is a common occurrence in several diseases and is mediated by... (Review)
Review
The multidrug resistance phenomenon presents a major threat to the pharmaceutical industry. This resistance is a common occurrence in several diseases and is mediated by multidrug transporters that actively pump substances out of the cell and away from their target regions. The most well-known multidrug transporter is the P-glycoprotein transporter. The binding sites within P-glycoprotein can accommodate a variety of compounds with diverse structures. Hence, numerous drugs are P-glycoprotein substrates, with new ones being identified every day. For many years, the mechanisms of action of P-glycoprotein have been shrouded in mystery, and scientists have only recently been able to elucidate certain structural and functional aspects of this protein. Although P-glycoprotein is highly implicated in multidrug resistant diseases, this transporter also performs various physiological roles in the human body and is expressed in several tissues, including the brain, kidneys, liver, gastrointestinal tract, testis, and placenta. The expression levels of P-glycoprotein are regulated by different enzymes, inflammatory mediators and transcription factors; alterations in which can result in the generation of a disease phenotype. This review details the discovery, the recently proposed structure and the regulatory functions of P-glycoprotein, as well as the crucial role it plays in health and disease.
PubMed: 35789865
DOI: 10.1016/j.heliyon.2022.e09777 -
Investigational New Drugs Feb 2021Ibrutinib is a first-in-class Bruton's kinase inhibitor used in the treatment of multiple lymphomas. In addition to CYP3A4-mediated metabolism, glutathione conjugation...
Ibrutinib is a first-in-class Bruton's kinase inhibitor used in the treatment of multiple lymphomas. In addition to CYP3A4-mediated metabolism, glutathione conjugation can be observed. Subsequently, metabolism of the conjugates and finally their excretion in feces and urine occurs. These metabolites, however, can reach substantial concentrations in human subjects, especially when CYP3A4 is inhibited. Ibrutinib has unexplained nephrotoxicity and high metabolite concentrations are also found in kidneys of Cyp3a knockout mice. Here, a mechanism is proposed where the intermediate cysteine metabolite is bioactivated. The metabolism of ibrutinib through this glutathione cycle was confirmed in cultured human renal proximal tubule cells. Ibrutinib-mediated toxicity was enhanced in-vitro by inhibitors of breast cancer resistance protein (BCRP), P-glycoprotein (P-gp) and multidrug resistance protein (MRP). This was a result of accumulating cysteine metabolite levels due to efflux inhibition. Finally, through inhibition of downstream metabolism, it was shown now that direct conjugation was responsible for cysteine metabolite toxicity.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP Binding Cassette Transporter, Subfamily G, Member 2; Acute Kidney Injury; Adenine; Aged; Animals; Antineoplastic Agents; Cell Survival; Cells, Cultured; Cytochrome P-450 CYP3A; Glutathione; Humans; Kidney Tubules, Proximal; Male; Mice; Mice, Knockout; Multidrug Resistance-Associated Proteins; Neoplasm Proteins; Piperidines
PubMed: 32623551
DOI: 10.1007/s10637-020-00970-x -
International Journal of Molecular... Jun 2023The ABC transporter P-glycoprotein (Pgp) has been found to be involved in multidrug resistance in tumor cells. Lipids and cholesterol have a pivotal role in Pgp's...
The ABC transporter P-glycoprotein (Pgp) has been found to be involved in multidrug resistance in tumor cells. Lipids and cholesterol have a pivotal role in Pgp's conformations; however, it is often difficult to investigate it with conventional structural biology techniques. Here, we applied robust approaches coupled with cross-linking mass spectrometry (XL-MS), where the natural lipid environment remains quasi-intact. Two experimental approaches were carried out using different cross-linkers (i) on living cells, followed by membrane preparation and immunoprecipitation enrichment of Pgp, and (ii) on-bead, subsequent to membrane preparation and immunoprecipitation. Pgp-containing complexes were enriched employing extracellular monoclonal anti-Pgp antibodies on magnetic beads, followed by on-bead enzymatic digestion. The LC-MS/MS results revealed mono-links on Pgp's solvent-accessible residues, while intraprotein cross-links confirmed a complex interplay between extracellular, transmembrane, and intracellular segments of the protein, of which several have been reported to be connected to cholesterol. Harnessing the MS results and those of molecular docking, we suggest an epitope for the 15D3 cholesterol-dependent mouse monoclonal antibody. Additionally, enriched neighbors of Pgp prove the strong connection of Pgp to the cytoskeleton and other cholesterol-regulated proteins. These findings suggest that XL-MS may be utilized for protein structure and network analyses in such convoluted systems as membrane proteins.
Topics: Animals; Mice; ATP Binding Cassette Transporter, Subfamily B, Member 1; Molecular Docking Simulation; Chromatography, Liquid; Tandem Mass Spectrometry; ATP Binding Cassette Transporter, Subfamily B; Cholesterol
PubMed: 37445813
DOI: 10.3390/ijms241310627 -
Clinical Pharmacology and Therapeutics Sep 2022The role of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) in drug-drug interactions (DDIs) and limiting drug absorption as well as restricting the... (Review)
Review
The role of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) in drug-drug interactions (DDIs) and limiting drug absorption as well as restricting the brain penetration of drugs with certain physicochemical properties is well known. P-gp/BCRP inhibition by drugs in the gut has been reported to increase the systemic exposure to substrate drugs. A previous International Transporter Consortium (ITC) perspective discussed the feasibility of P-gp/BCRP inhibition at the blood-brain barrier and its implications. This ITC perspective elaborates and discusses specifically the hepatic and renal P-gp/BCRP (referred as systemic) inhibition of drugs and whether there is any consequence for substrate drug disposition. This perspective summarizes the clinical evidence-based recommendations regarding systemic P-gp and BCRP inhibition of drugs with a focus on biliary and active renal excretion pathways. Approaches to assess the clinical relevance of systemic P-gp and BCRP inhibition in the liver and kidneys included (i) curation of DDIs involving intravenously administered substrates or inhibitors; (ii) in vitro-to-in vivo extrapolation of P-gp-mediated DDIs at the systemic level; and (iii) curation of drugs with information available about the contribution of biliary excretion and related DDIs. Based on the totality of evidence reported to date, this perspective supports limited clinical DDI risk upon P-gp or BCRP inhibition in the liver or kidneys.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; ATP Binding Cassette Transporter, Subfamily G, Member 2; Humans; Liver; Membrane Transport Proteins; Neoplasm Proteins
PubMed: 35612761
DOI: 10.1002/cpt.2670 -
Biochimica Et Biophysica Acta.... Jan 2020P-glycoprotein (Pgp) is a biomedically important member of the ABC transporter superfamily that mediates multidrug resistance in various cancer types. Substrate binding...
P-glycoprotein (Pgp) is a biomedically important member of the ABC transporter superfamily that mediates multidrug resistance in various cancer types. Substrate binding and transport in Pgp are modulated by the presence of cholesterol in the membrane. Structural information on cholesterol binding sites and mechanistic details of its redistribution are, however, largely unknown. In this study, a set of 40 independent molecular dynamics (MD) simulations of Pgp embedded in cholesterol-rich lipid bilayers are reported, totaling 8 μs, enabling extensive sampling of cholesterol-protein interactions in Pgp. Clustering analyses of the ensemble of cholesterol molecules (∼5740) sampled around Pgp in these simulations reveal specific and asymmetric cholesterol-binding regions formed by the transmembrane (TM) helices TM1-6 and TM8. Notably, not all the putative cholesterol binding sites identified by MD can be predicted by the primary sequence based cholesterol-recognition amino acid consensus (CRAC) or inverted CRAC (CARC) motifs, an observation that we attribute to inadequacy of these motifs to account for binding sites formed by remote amino acids in the sequence that can still be spatially adjacent to each other. Binding of cholesterol to Pgp occurs more frequently through its rough β-face formed by the two protruding methyl groups, whereas the opposite smooth α-face prefers packing alongside the membrane lipids. One full and two partial cholesterol flipping events between the two leaflets of the bilayer mediated by the surface of Pgp are also captured in these simulations. All flipping events are observed in a region formed by helices TM1, TM2, and TM11, featuring two full and two partial CRAC/CARC motifs, with Tyr49 and Tyr126 identified as key residues interacting with cholesterol during this event. Our study is the first to report direct observation of unconventional cholesterol translocation on the surface of Pgp, providing a secondary transport model for the known flippase activity of ABC exporters of cholesterol. This article is part of a Special Issue entitled: Molecular biophysics of membranes and membrane proteins.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Amino Acid Sequence; Binding Sites; Biological Transport; Cholesterol; Lipid Bilayers; Molecular Dynamics Simulation; Tyrosine
PubMed: 31676371
DOI: 10.1016/j.bbamem.2019.183090 -
European Journal of Nuclear Medicine... Nov 2023P-glycoprotein (P-gp) is one of the most studied efflux transporters at the blood-brain barrier. It plays an important role in brain homeostasis by protecting the brain...
INTRODUCTION
P-glycoprotein (P-gp) is one of the most studied efflux transporters at the blood-brain barrier. It plays an important role in brain homeostasis by protecting the brain from a variety of endogenous and exogeneous substances. Changes in P-gp function are associated both with the onset of neuropsychiatric diseases, including Alzheimer's disease and Parkinson's disease, and with drug-resistance, for example in treatment-resistant depression. The most widely used approach to measure P-gp function in vivo is (R)-[C]verapamil PET. (R)-[C]verapamil is, however, an avid P-gp substrate, which complicates the use of this tracer to measure an increase in P-gp function as its baseline uptake is already very low. [F]MC225 was developed to measure both increases and decreases in P-gp function.
AIM
The aim of this study was (1) to identify the pharmacokinetic model that best describes [F]MC225 kinetics in the human brain and (2) to determine test-retest variability.
METHODS
Five (2 male, 3 female) of fourteen healthy subjects (8 male, 6 female, age 67 ± 5 years) were scanned twice (injected dose 201 ± 47 MBq) with a minimum interval of 2 weeks between scans. Each scanning session consisted of a 60-min dynamic [F]MC225 scan with continuous arterial sampling. Whole brain grey matter data were fitted to a single tissue compartment model, and to reversible and irreversible two tissue-compartment models to obtain various outcome parameters (in particular the volume of distribution (V), K, and the rate constants K and k). In addition, a reversible two-tissue compartment model with fixed k/k was included. The preferred model was selected based on the weighted Akaike Information Criterion (AIC) score. Test-retest variability (TRTV) was determined to assess reproducibility.
RESULTS
Sixty minutes post-injection, the parent fraction was 63.8 ± 4.0%. The reversible two tissue compartment model corrected for plasma metabolites with an estimated blood volume (V) showed the highest AIC weight score of 34.3 ± 17.6%. The TRVT of the V for [F]MC225 PET scans was 28.3 ± 20.4% for the whole brain grey matter region using this preferred model.
CONCLUSION
[F]MC225 V, derived using a reversible two-tissue compartment model, is the preferred parameter to describe P-gp function in the human BBB. This outcome parameter has an average test-retest variability of 28%.
TRIAL REGISTRATION
EudraCT 2020-001564-28 . Registered 25 May 2020.
Topics: Humans; Male; Female; Middle Aged; Aged; Blood-Brain Barrier; ATP Binding Cassette Transporter, Subfamily B, Member 1; Reproducibility of Results; Brain; ATP Binding Cassette Transporter, Subfamily B; Positron-Emission Tomography; Verapamil; Radiopharmaceuticals
PubMed: 37552369
DOI: 10.1007/s00259-023-06363-5 -
Journal of Veterinary Science Sep 2021Hepatocellular carcinoma is the most common primary hepatic malignancy in humans and dogs. Several differentially expressed molecules have been studied and reported in...
BACKGROUND
Hepatocellular carcinoma is the most common primary hepatic malignancy in humans and dogs. Several differentially expressed molecules have been studied and reported in human hepatocellular carcinoma and non-neoplastic liver lesions. However, studies on the features of canine hepatocellular carcinoma are limited, especially related to the differential characteristics of neoplastic and non-neoplastic lesions.
OBJECTIVES
The study's objective was 1) to examine and evaluate the expression of arginase-1, P-glycoprotein, and cytokeratin 19 in canine liver tissues and 2) to investigate the differential features of hepatocellular carcinomas, liver tissue with non-neoplastic lesions, and paracancerous liver tissues in dogs.
METHODS
The expression levels of three markers underwent immunohistochemical analysis in 40 non-neoplastic liver tissues, 32 hepatocellular carcinoma tissues, and 11 paracancerous liver tissues. Scoring of each marker was performed semi-quantitatively.
RESULTS
Arginase-1 and P-glycoprotein were significantly downregulated in hepatocellular carcinoma, compared with hepatic tissues with non-neoplastic diseases ( < 0.001). Expression levels of arginase-1 and P-glycoprotein were also significantly lower in hepatocellular carcinoma than in paracancerous liver tissues (arginase-1, 0.0195; P-glycoprotein, 0.047). Few cytokeratin 19-positive hepatocytes were detected and only in one hepatocellular carcinoma and one cirrhotic liver sample.
CONCLUSIONS
The results of this study suggest that downregulation of arginase-1 and P-glycoprotein is a feature of canine hepatocellular carcinoma; thus, those markers are potential candidates for use in differentiating hepatocellular carcinomas from non-neoplastic liver lesions in dogs.
Topics: ATP Binding Cassette Transporter, Subfamily B, Member 1; Animals; Arginase; Carcinoma, Hepatocellular; Dog Diseases; Dogs; Down-Regulation
PubMed: 34423599
DOI: 10.4142/jvs.2021.22.e61 -
International Journal of Molecular... Feb 2023Acute myeloid leukemia (AML) remains an insidious neoplasm due to the percentage of patients who develop resistance to both classic chemotherapy and emerging drugs.... (Review)
Review
Acute myeloid leukemia (AML) remains an insidious neoplasm due to the percentage of patients who develop resistance to both classic chemotherapy and emerging drugs. Multidrug resistance (MDR) is a complex process determined by multiple mechanisms, and it is often caused by the overexpression of efflux pumps, the most important of which is P-glycoprotein (P-gp). This mini-review aims to examine the advantages of using natural substances as P-gp inhibitors, focusing on four molecules: phytol, curcumin, lupeol, and heptacosane, and their mechanism of action in AML.
Topics: Humans; ATP Binding Cassette Transporter, Subfamily B, Member 1; Curcumin; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Leukemia, Myeloid, Acute
PubMed: 36835550
DOI: 10.3390/ijms24044140