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Sharom FJ. Complex Interplay between the P-Glycoprotein Multidrug Efflux Pump and the Membrane: Its Role in Modulating Protein Function. Front Oncol 2014; 4:41. [PMID: 24624364 PMCID: PMC3939933 DOI: 10.3389/fonc.2014.00041] [Citation(s) in RCA: 184] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 02/17/2014] [Indexed: 11/16/2022] Open
Abstract
Multidrug resistance in cancer is linked to expression of the P-glycoprotein multidrug transporter (Pgp, ABCB1), which exports many structurally diverse compounds from cells. Substrates first partition into the bilayer and then interact with a large flexible binding pocket within the transporter's transmembrane regions. Pgp has been described as a hydrophobic vacuum cleaner or an outwardly directed drug/lipid flippase. Recent X-ray crystal structures have shed some light on the nature of the drug-binding pocket and suggested routes by which substrates can enter it from the membrane. Detergents have profound effects on Pgp function, and several appear to be substrates. Biochemical and biophysical studies in vitro, some using purified reconstituted protein, have explored the effects of the membrane environment. They have demonstrated that Pgp is involved in a complex relationship with its lipid environment, which modulates the behavior of its substrates, as well as various functions of the protein, including ATP hydrolysis, drug binding, and drug transport. Membrane lipid composition and fluidity, phospholipid headgroup and acyl chain length all influence Pgp function. Recent studies focusing on thermodynamics and kinetics have revealed some important principles governing Pgp-lipid and substrate-lipid interactions, and how these affect drug-binding and transport. In some cells, Pgp is associated with cholesterol-rich microdomains, which may modulate its functions. The relationship between Pgp and cholesterol remains an open question; however, it clearly affects several aspects of its function in addition to substrate-membrane partitioning. The action of Pgp modulators appears to depend on their membrane permeability, and membrane fluidizers and surfactants reverse drug resistance, likely via an indirect mechanism. A detailed understanding of how the membrane affects Pgp substrates and Pgp's catalytic cycle may lead to new strategies to combat clinical drug resistance.
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Affiliation(s)
- Frances Jane Sharom
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
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Kim C, Cadet P. Environmental toxin 4-nonylphenol and autoimmune diseases: using DNA microarray to examine genetic markers of cytokine expression. Arch Med Sci 2010; 6:321-7. [PMID: 22371766 PMCID: PMC3282507 DOI: 10.5114/aoms.2010.14250] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 05/30/2010] [Accepted: 06/03/2010] [Indexed: 11/17/2022] Open
Abstract
INTRODUCTION Adverse progression of autoimmune diseases is linked to the dysregulation of cytokines. In this regard we investigated the role of 4-nonylphenol (4-NP), as a potential contributing factor in the development of immune diseases and compared it to estrogens actions since 4-NP may work via estrogen processes. MATERIAL AND METHODS The study made cytokine level expression changes in U937 cells by microarray technology coupled to RT PCR as a validating technique. RESULTS It was determined that 4-NP significantly up-regulated proinflammatory cytokine expression (toll-like-receptor [TLR]-6, TLR-10, interleukin [IL]-1, IL-5, IL-6, IL-17C, IL-23A, IL-8RB, IL-receptor-associated-kinase [IRAK-2], tumor-necrosis-factor-receptor [TNFR]-5, and TNFR-10). Estrogen caused insignificant increases but the changes parralelled that of 4-NP. Simultaneously, 4-NP down-regulated the expression of anti-inflammatory cytokines (IL-4 and IL-10), while estrogen up-regulated them. CONCLUSIONS 4-Nonylphenol may initiate its toxic effects and pose a risk to autoimmunity-prone individuals by eliciting effects up to 4 times more potent than estrogen. Overall, exposure to 4-NP may contribute to autoimmune susceptibility and/or exacerbate existing autoimmune conditions by dys-regulating normal expression of cytokines.
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Affiliation(s)
- Celline Kim
- Neuroscience Research Institute, State University of New York, College at Old Westbury, Old Westbury, USA
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de la Fuente L, Acosta T, Babay P, Curutchet G, Candal R, Litter MI. Degradation of Nonylphenol Ethoxylate-9 (NPE-9) by Photochemical Advanced Oxidation Technologies. Ind Eng Chem Res 2010. [DOI: 10.1021/ie901785j] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Luciana de la Fuente
- Gerencia Química, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires, Argentina, Escuela de Ciencia y Tecnología, Universidad de General San Martín, 25 de Mayo y Martín de Irigoyen, 1650 San Martín, Provincia de Buenos Aires, Argentina, Instituto de Investigación e Ingeniería Ambiental, Universidad de General San Martín, Peatonal Belgrano 3563, 1650 San Martín, Provincia de Buenos Aires, Argentina, and Consejo Nacional de Investigaciones Científicas
| | - Tatiana Acosta
- Gerencia Química, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires, Argentina, Escuela de Ciencia y Tecnología, Universidad de General San Martín, 25 de Mayo y Martín de Irigoyen, 1650 San Martín, Provincia de Buenos Aires, Argentina, Instituto de Investigación e Ingeniería Ambiental, Universidad de General San Martín, Peatonal Belgrano 3563, 1650 San Martín, Provincia de Buenos Aires, Argentina, and Consejo Nacional de Investigaciones Científicas
| | - Paola Babay
- Gerencia Química, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires, Argentina, Escuela de Ciencia y Tecnología, Universidad de General San Martín, 25 de Mayo y Martín de Irigoyen, 1650 San Martín, Provincia de Buenos Aires, Argentina, Instituto de Investigación e Ingeniería Ambiental, Universidad de General San Martín, Peatonal Belgrano 3563, 1650 San Martín, Provincia de Buenos Aires, Argentina, and Consejo Nacional de Investigaciones Científicas
| | - Gustavo Curutchet
- Gerencia Química, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires, Argentina, Escuela de Ciencia y Tecnología, Universidad de General San Martín, 25 de Mayo y Martín de Irigoyen, 1650 San Martín, Provincia de Buenos Aires, Argentina, Instituto de Investigación e Ingeniería Ambiental, Universidad de General San Martín, Peatonal Belgrano 3563, 1650 San Martín, Provincia de Buenos Aires, Argentina, and Consejo Nacional de Investigaciones Científicas
| | - Roberto Candal
- Gerencia Química, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires, Argentina, Escuela de Ciencia y Tecnología, Universidad de General San Martín, 25 de Mayo y Martín de Irigoyen, 1650 San Martín, Provincia de Buenos Aires, Argentina, Instituto de Investigación e Ingeniería Ambiental, Universidad de General San Martín, Peatonal Belgrano 3563, 1650 San Martín, Provincia de Buenos Aires, Argentina, and Consejo Nacional de Investigaciones Científicas
| | - Marta I. Litter
- Gerencia Química, Comisión Nacional de Energía Atómica, Avenida General Paz 1499, 1650 San Martín, Provincia de Buenos Aires, Argentina, Escuela de Ciencia y Tecnología, Universidad de General San Martín, 25 de Mayo y Martín de Irigoyen, 1650 San Martín, Provincia de Buenos Aires, Argentina, Instituto de Investigación e Ingeniería Ambiental, Universidad de General San Martín, Peatonal Belgrano 3563, 1650 San Martín, Provincia de Buenos Aires, Argentina, and Consejo Nacional de Investigaciones Científicas
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Crandall I, Charuk J, Kain KC. Nonylphenolethoxylates as malarial chloroquine resistance reversal agents. Antimicrob Agents Chemother 2000; 44:2431-4. [PMID: 10952591 PMCID: PMC90081 DOI: 10.1128/aac.44.9.2431-2434.2000] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Malaria-associated morbidity and mortality are increasing because of widespread resistance to one of the safest and least expensive antimalarials, chloroquine. The availability of an inexpensive agent that is capable of reversing chloroquine resistance would have a major impact on malaria treatment worldwide. The interaction of nonylphenolethoxylates (NPEs, commercially available synthetic surfactants) with drug-resistant Plasmodium falciparum was examined to determine if NPEs inhibited the growth of the parasites and if NPEs could sensitize resistant parasites to chloroquine. NPEs inhibited the development of the parasite when present in the low- to mid-micromolar range (5 to 90 microM), indicating that they possess antimalarial activity. Further, the presence of <10 microM concentrations of NPEs caused the 50% inhibitory concentrations for chloroquine-resistant lines to drop to levels (< or =12 nM) observed for sensitive lines and generally considered to be achievable with treatment courses of chloroquine. Long-chain (>30 ethoxylate units) NPEs were found to be most active in P. falciparum, which contrasts with previously observed maximal activity of short-chain ( approximately 9 ethoxylate units) NPEs in multidrug-resistant mammalian cell lines. NPEs may be attractive chloroquine resistance reversal agents since they are inexpensive and may be selectively directed against P. falciparum without inhibiting mammalian tissue P glycoproteins. Antimalarial preparations that include these agents may prolong the effective life span of chloroquine and other antimalarials.
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Affiliation(s)
- I Crandall
- Tropical Disease Unit, The Toronto Hospital, University of Toronto, Ontario, Canada.
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Loo TW, Clarke DM. The human multidrug resistance P-glycoprotein is inactive when its maturation is inhibited: potential for a role in cancer chemotherapy. FASEB J 1999; 13:1724-32. [PMID: 10506575 DOI: 10.1096/fasebj.13.13.1724] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The human multidrug resistance P-glycoprotein (P-gp) contributes to the phenomenon of multidrug resistance during cancer and AIDS chemotherapy. A potential novel strategy to circumvent the effects of P-gp during chemotherapy is to prevent maturation of P-gp during biosynthesis so that the transporter does not reach the cell surface. Here we report that immature, core-glycosylated P-gp that is prevented from reaching the cell surface by processing mutations or by proteasome inhibitors such as lactacystin or MG-132 exhibited no detectable drug-stimulated ATPase activity. Disulfide cross-linking analysis also showed that the immature P-gp did not exhibit ATP-induced conformational changes as found in the mature enzyme. In addition, the immature P-gp was more sensitive to trypsin than the mature enzyme. These results suggest that P-gp is unlikely to be functional immediately after synthesis. These differences in the structural and enzymatic properties of the mature and core-glycosylated, immature P-gp could potentially be used during chemotherapy, and should result in the search for compounds that can specifically inhibit the maturation of P-gp.
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Affiliation(s)
- T W Loo
- MRC Group in Membrane Biology, Department of Medicine and Department of Biochemistry, University of Toronto, Ontario M5S 1A8, Canada
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