scholarly journals Providing a molecular mechanism for P-glycoprotein; why would I bother?

2015 ◽  
Vol 43 (5) ◽  
pp. 995-1002 ◽  
Author(s):  
Richard Callaghan
Keyword(s):  
Cancer Cells ◽  
Molecular Mechanism ◽  
Conformational Changes ◽  
Efflux Pump ◽  
Structural Data ◽  
Multi Drug Resistance ◽  
P Glycoprotein ◽  
Complex Protein ◽  
Cytosolic Domains ◽  
Drug Efflux Pump

It is almost 40 years since the drug efflux pump P-glycoprotein (permeability glycoprotein or P-gp) was shown to confer multi-drug resistance in cancer cells. This protein has been one of the most extensively investigated transport proteins due to its intriguing mechanism and its affect in oncology. P-gp is known to interact with over 300 compounds and the ability to achieve this has not yet been revealed. Following the binding of substrate and nucleotide, a complex series of conformational changes in the membrane and cytosolic domains translocates substrate across the membrane. Despite over 30 years of biochemical investigation, the availability of structural data and a plethora of chemical tools to modulate its function, the molecular mechanism remains a mystery. In addition, overcoming its activity in resistant cancer cells has not been achieved in the clinic, thereby garnering some degree of pessimism in the field. This review highlights the progress that has been achieved in understanding this complex protein and the value of undertaking molecular studies.

Human hepatocellular carcinoma cell lines exhibit multidrug resistance unrelated to MRD1 gene expression

1991 ◽  
Vol 98 (3) ◽  
pp. 317-322
Author(s):  
D.W. Shen ◽  
Y.G. Lu ◽  
K.V. Chin ◽  
I. Pastan ◽  
M.M. Gottesman
Keyword(s):  
Hepatocellular Carcinoma ◽  
Multidrug Resistance ◽  
Cancer Cells ◽  
Cell Lines ◽  
Actinomycin D ◽  
Efflux Pump ◽  
Mdr1 Gene ◽  
Drug Efflux ◽  
P Glycoprotein ◽  
Drug Efflux Pump

Multidrug resistance of human cancer cells may result from expression of P-glycoprotein, the product of the MRD1 gene, acting as an energy-dependent drug efflux pump. However, direct evidence that expression of the MDR1 gene contributes to the multidrug resistance of human liver carcinomas has not been established. In this study, we tested five cell lines derived from human hepatocellular carcinomas for sensitivity to a variety of drugs used widely as anticancer agents; these included vinblastine, doxorubicin, actinomycin D, mitomycin C, 5-fluorouracil, 6-mercaptopurine, melphalan, methotrexate, cis-platinum and etoposide (VP-16). All five hepatoma cell lines were resistant at different levels to these chemicals compared to human KB cells. Although it has been demonstrated that resistance to vinblastine, colchicine, doxorubicin and actinomycin D in human multidrug-resistant cells is associated with overexpression of P-glycoprotein, very little expression of P-glycoprotein was found in these human hepatoma cells. Neither verapamil nor quinidine, inhibitors of the drug efflux pump, were able to overcome multidrug resistance in hepatoma cells. These results indicate that the multidrug resistance phenotype in human hepatocellular carcinoma cells cannot be attributed to expression of the MDR1 gene, but that novel mechanisms may account for the resistance of these cancer cells.

scholarly journals Caffeic Acid Attenuates Multi-Drug Resistance in Cancer Cells by Inhibiting Efflux Function of Human P-Glycoprotein

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 247
Author(s):  
Yu-Ning Teng ◽  
Charles C.N. Wang ◽  
Wei-Chieh Liao ◽  
Yu-Hsuan Lan ◽  
Chin-Chuan Hung
Keyword(s):  
Atpase Activity ◽  
Caffeic Acid ◽  
Efflux Pump ◽  
Multi Drug Resistance ◽  
Drug Efflux ◽  
Promising Candidate ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Calcein Am ◽  
Drug Efflux Pump

Multidrug resistance (MDR) is a complicated ever-changing problem in cancer treatment, and P-glycoprotein (P-gp), a drug efflux pump, is regarded as the major cause. In the way of developing P-gp inhibitors, natural products such as phenolic acids have gotten a lot of attention recently. The aim of the present study was to investigate the modulating effects and mechanisms of caffeic acid on human P-gp, as well as the attenuating ability on cancer MDR. Calcein-AM, rhodamine123, and doxorubicin were used to analyze the interaction between caffeic acid and P-gp, and the ATPase activity of P-gp was evaluated as well. Resistance reversing effects were revealed by SRB and cell cycle assay. The results indicated that caffeic acid uncompetitively inhibited rhodamine123 efflux and competitively inhibited doxorubicin efflux. In terms of P-gp ATPase activity, caffeic acid exhibited stimulation in both basal and verapamil-stimulated activity. The combination of chemo drugs and caffeic acid resulted in decreased IC50 in ABCB1/Flp-InTM-293 and KB/VIN, indicating that the resistance was reversed. Results of molecular docking suggested that caffeic acid bound to P-gp through GLU74 and TRY117 residues. The present study demonstrated that caffeic acid is a promising candidate for P-gp inhibition and cancer MDR attenuation.

P-glycoprotein as the drug efflux pump in primary cultured bovine brain capillary endothelial cells

Life Sciences ◽  
1992 ◽  
Vol 51 (18) ◽  
pp. 1427-1437 ◽  
Author(s):  
Akira Tsuji ◽  
Tetsuya Terasaki ◽  
Yasushi Takabatake ◽  
Yoshiyuki Tenda ◽  
Ikumi Tamai ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Efflux Pump ◽  
Bovine Brain ◽  
Drug Efflux ◽  
Brain Capillary ◽  
Brain Capillary Endothelial Cells ◽  
P Glycoprotein ◽  
Capillary Endothelial Cells ◽  
Drug Efflux Pump

Modeling of P-glycoprotein-involved epithelial drug transport in MDCK cells

1999 ◽  
Vol 277 (1) ◽  
pp. F84-F96 ◽  
Author(s):  
Shinya Ito ◽  
Cindy Woodland ◽  
Balázs Sarkadi ◽  
Guido Hockmann ◽  
Scott E. Walker ◽  
...  
Keyword(s):  
Drug Transport ◽  
Diffusion Processes ◽  
Efflux Pump ◽  
Mdck Cells ◽  
Basolateral Membrane ◽  
Drug Efflux ◽  
Drug Transfer ◽  
P Glycoprotein ◽  
Drug Efflux Pump ◽  
Apical Membranes

P-glycoprotein (P-gp) on the apical membranes of epithelial cells is known as a drug efflux pump. However, unclear is its integral quantitative role in the overall epithelial drug transfer, which also involves distinct diffusion processes in parallel and sequence. We used a simple three-compartment model to obtain kinetic parameters of each drug transfer mechanism, which can quantitatively describe the transport time courses of P-gp substrates, digoxin and vinblastine, across P-gp-expressing MDCK cell monolayers grown on permeable filters. Our results show that the model, which assumes a functionally single drug efflux pump in the apical membrane with diffusion across two membranes and intercellular junctions, is the least complex model with which to quantitatively reproduce the characteristics of the data. Interestingly, the model predicts that the MDCK apical membranes are less diffusion permeable than the basolateral membrane for both drugs and that the distribution volume of vinblastine is 10-fold higher than that of digoxin. Additional experiments verified these model predictions. The modeling approach is feasible to quantitatively describe overall kinetic picture of epithelial drug transport. Further model refinement is necessary to incorporate other modes of drug transport such as transcytosis. Also, whether P-gp solely accounts for the pump function in this model awaits more studies.

scholarly journals Thyroid Hormone and P-Glycoprotein in Tumor Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Paul J. Davis ◽  
Sandra Incerpi ◽  
Hung-Yun Lin ◽  
Heng-Yuan Tang ◽  
Thangirala Sudha ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Cancer Cells ◽  
Cancer Cell ◽  
Molecular Mechanisms ◽  
Efflux Pump ◽  
Inhibitory Effect ◽  
Chemotherapeutic Agents ◽  
Cell Surface Receptor ◽  
P Glycoprotein ◽  
Surface Receptor

P-glycoprotein (P-gp; multidrug resistance pump 1, MDR1; ABCB1) is a plasma membrane efflux pump that when activated in cancer cells exports chemotherapeutic agents. Transcription of the P-gp gene (MDR1) and activity of the P-gp protein are known to be affected by thyroid hormone. A cell surface receptor for thyroid hormone on integrinαvβ3 also binds tetraiodothyroacetic acid (tetrac), a derivative of L-thyroxine (T4) that blocks nongenomic actions of T4and of 3,5,3′-triiodo-L-thyronine (T3) atαvβ3. Covalently bound to a nanoparticle, tetrac as nanotetrac acts at the integrin to increase intracellular residence time of chemotherapeutic agents such as doxorubicin and etoposide that are substrates of P-gp. This action chemosensitizes cancer cells. In this review, we examine possible molecular mechanisms for the inhibitory effect of nanotetrac on P-gp activity. Mechanisms for consideration include cancer cell acidification via action of tetrac/nanotetrac on the Na+/H+exchanger (NHE1) and hormone analogue effects on calmodulin-dependent processes and on interactions of P-gp with epidermal growth factor (EGF) and osteopontin (OPN), apparently viaαvβ3. Intracellular acidification and decreased H+efflux induced by tetrac/nanotetrac via NHE1 is the most attractive explanation for the actions on P-gp and consequent increase in cancer cell retention of chemotherapeutic agent-ligands of MDR1 protein.

scholarly journals Overcoming P-Glycoprotein-Mediated Doxorubicin Resistance

2021 ◽  
Author(s):  
Suree Jianmongkol
Keyword(s):  
Cancer Cells ◽  
Multi Drug Resistance ◽  
Therapeutic Success ◽  
Glycoprotein P ◽  
Target Delivery ◽  
Doxorubicin Treatment ◽  
Doxorubicin Resistance ◽  
P Glycoprotein ◽  
Strategic Approach ◽  
Effective Level

Intracellular concentration of doxorubicin in target cancer cells is a major determinant of therapeutic success of doxorubicin-based regimens. As known, doxorubicin is a substrate of P-glycoprotein (P-gp), the drug efflux transporter in the ABC superfamily. High expression level of P-gp in cancer cells can prevent intracellular accumulation of doxorubicin up to its effective level, leading to doxorubicin resistance and treatment failure. Moreover, these P-gp-overexpressed cells display multi-drug resistance (MDR) phenotype. Regarding this, application of P-gp modulators (suppressor of P-gp activity and expression) is likely to reverse MDR and restore cell sensitivity to doxorubicin treatment. In searching for potential chemo-sensitizer against resistant cancer, a number of phytochemicals or dietary compounds have been studied extensively for their P-gp modulating effects. Furthermore, combination between doxorubicin and P-gp modulators (e.g., plant-derived compounds, siRNA) given through specific target delivery platforms have been an effective strategic approach for MDR reversal and restore doxorubicin effectiveness for cancer treatment.

scholarly journals The Effects of TiO2 Nanoparticles on Cisplatin Cytotoxicity in Cancer Cell Lines

2020 ◽  
Vol 21 (2) ◽  
pp. 605 ◽  
Author(s):  
Basma Salama ◽  
El-Said El-Sherbini ◽  
Gehad El-Sayed ◽  
Mohamed El-Adl ◽  
Koki Kanehira ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Cancer Cells ◽  
Hepg2 Cells ◽  
Titanium Dioxide Nanoparticles ◽  
Membrane Receptors ◽  
Multi Drug Resistance ◽  
A431 Cells ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Low Expression

There have been many studies on improving the efficacy of cisplatin and on identifying safe compounds that can overcome multi-drug resistance (MDR) acquired by cancer cells. Our previous research showed that polyethylene glycol-modified titanium dioxide nanoparticles (TiO2 PEG NPs) affect cell membrane receptors, resulting in their aggregation, altered localization and downregulation. TiO2 PEG NPs may affect P-glycoprotein (P-gp), a membrane efflux channel involved in MDR. In this study, we investigated the effect of TiO2 PEG NPs on cisplatin cytotoxicity. We used HepG2 cells, which highly express P-gp and A431 cells, which show low expression of P-gp. The results showed that 10 µg/mL 100 nm TiO2 PEG NPs increased intracellular cisplatin levels and cytotoxicity in HepG2 cells but not in A431 cells. TiO2 PEG NPs treatment decreased the expression level of P-gp in HepG2 cells. Our findings indicate that TiO2 PEG NPs enhance cisplatin cytotoxicity by down regulating P-gp and that TiO2 PEG NPs are promising candidates for inhibiting P-gp and reversing drug resistance acquired by cancer cells.

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