1
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The Interplay of ABC Transporters in Aβ Translocation and Cholesterol Metabolism: Implicating Their Roles in Alzheimer's Disease. Mol Neurobiol 2020; 58:1564-1582. [PMID: 33215389 DOI: 10.1007/s12035-020-02211-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 11/13/2020] [Indexed: 02/06/2023]
Abstract
The occurrence of Alzheimer's disease (AD) worldwide has been progressively accelerating at an alarming rate, without any successful therapeutic strategy for the disease mitigation. The complexity of AD pathogenesis needs to be targeted with an alternative approach, as provided by the superfamily of ATP-binding cassette (ABC) transporters, which constitutes an extensive range of proteins, capable of transporting molecular entities across biological membranes. These protein moieties have been implicated in AD, based upon their potential in lipid transportation, resulting in maintenance of cholesterol homeostasis. These transporters have been reported to target the primary hallmark of AD pathogenesis, namely, beta-amyloid hypothesis, which is associated with accumulation of beta-amyloid (Aβ) plaques in AD patients. The ABC transporters have been observed to be localized to the capillary endothelial cells of the blood-brain barrier and neural parenchymal cells, where they exhibit different roles, consequently influencing the neuronal expression of Aβ peptides. The review highlights different families of ABC transporters, ABCB1 (P-glycoprotein), ABCA (ABCA1, ABCA2, and ABCA7), ABCG2 (BCRP; breast cancer resistance protein), ABCG1 and ABCG4, as well as ABCC1 (MRP; multidrug resistance protein) in the CNS, and their interplay in regulating cholesterol metabolism and Aβ peptide load in the brain, simultaneously exerting protective effects against neurotoxic substrates and xenobiotics. The authors aim to establish the significance of this alternative approach as a novel therapeutic target in AD, to provide the researchers an opportunity to evaluate the potential aspects of ABC transporters in AD treatment.
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2
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You D, Richardson JR, Aleksunes LM. Epigenetic Regulation of Multidrug Resistance Protein 1 and Breast Cancer Resistance Protein Transporters by Histone Deacetylase Inhibition. Drug Metab Dispos 2020; 48:459-480. [PMID: 32193359 PMCID: PMC7250367 DOI: 10.1124/dmd.119.089953] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 02/13/2020] [Indexed: 02/06/2023] Open
Abstract
Multidrug resistance protein 1 (MDR1, ABCB1, P-glycoprotein) and breast cancer resistance protein (BCRP, ABCG2) are key efflux transporters that mediate the extrusion of drugs and toxicants in cancer cells and healthy tissues, including the liver, kidneys, and the brain. Altering the expression and activity of MDR1 and BCRP influences the disposition, pharmacodynamics, and toxicity of chemicals, including a number of commonly prescribed medications. Histone acetylation is an epigenetic modification that can regulate gene expression by changing the accessibility of the genome to transcriptional regulators and transcriptional machinery. Recently, studies have suggested that pharmacological inhibition of histone deacetylases (HDACs) modulates the expression and function of MDR1 and BCRP transporters as a result of enhanced histone acetylation. This review addresses the ability of HDAC inhibitors to modulate the expression and the function of MDR1 and BCRP transporters and explores the molecular mechanisms by which HDAC inhibition regulates these transporters. While the majority of studies have focused on histone regulation of MDR1 and BCRP in drug-resistant and drug-sensitive cancer cells, emerging data point to similar responses in nonmalignant cells and tissues. Elucidating epigenetic mechanisms regulating MDR1 and BCRP is important to expand our understanding of the basic biology of these two key transporters and subsequent consequences on chemoresistance as well as tissue exposure and responses to drugs and toxicants. SIGNIFICANCE STATEMENT: Histone deacetylase inhibitors alter the expression of key efflux transporters multidrug resistance protein 1 and breast cancer resistance protein in healthy and malignant cells.
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Affiliation(s)
- Dahea You
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, New Jersey (D.Y.); Department of Environmental Health Sciences, Robert Stempel School of Public Health and Social Work, Florida International University, Miami, Florida (J.R.R.); Environmental and Occupational Health Sciences Institute, Piscataway, New Jersey (J.R.R., L.M.A.); and Department of Pharmacology and Toxicology, Rutgers, The State University of New Jersey, Ernest Mario School of Pharmacy, Piscataway, New Jersey (L.M.A.)
| | - Jason R Richardson
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, New Jersey (D.Y.); Department of Environmental Health Sciences, Robert Stempel School of Public Health and Social Work, Florida International University, Miami, Florida (J.R.R.); Environmental and Occupational Health Sciences Institute, Piscataway, New Jersey (J.R.R., L.M.A.); and Department of Pharmacology and Toxicology, Rutgers, The State University of New Jersey, Ernest Mario School of Pharmacy, Piscataway, New Jersey (L.M.A.)
| | - Lauren M Aleksunes
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, New Jersey (D.Y.); Department of Environmental Health Sciences, Robert Stempel School of Public Health and Social Work, Florida International University, Miami, Florida (J.R.R.); Environmental and Occupational Health Sciences Institute, Piscataway, New Jersey (J.R.R., L.M.A.); and Department of Pharmacology and Toxicology, Rutgers, The State University of New Jersey, Ernest Mario School of Pharmacy, Piscataway, New Jersey (L.M.A.)
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3
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Thorne JL, Battaglia S, Baxter DE, Hayes JL, Hutchinson SA, Jana S, Millican-Slater RA, Smith L, Teske MC, Wastall LM, Hughes TA. MiR-19b non-canonical binding is directed by HuR and confers chemosensitivity through regulation of P-glycoprotein in breast cancer. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1861:996-1006. [DOI: 10.1016/j.bbagrm.2018.08.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 07/09/2018] [Accepted: 08/23/2018] [Indexed: 12/25/2022]
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4
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Zhao P, Wang S, Jiang J, Liu H, Zhu X, Zhao N, Li J, Yin Y, Pan X, Yang X, Guo J, Xu W. TIPE2 sensitizes osteosarcoma cells to cis-platin by down-regulating MDR1 via the TAK1- NF-κB and - AP-1 pathways. Mol Immunol 2018; 101:471-478. [PMID: 30114619 DOI: 10.1016/j.molimm.2018.08.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 07/06/2018] [Accepted: 08/08/2018] [Indexed: 12/16/2022]
Abstract
TIPE2 participates in multiple types of cancer development. However, its mechanism underlying chemoresistance in osteosarcoma has not been elucidated. Herein, we observed the expression of TIPE2 and MDR1 in cis-platin-resistant osteosarcoma tissues and cell lines. Compared to their matched sensitive cell lines and tissues, TIPE2 was downregulated while MDR1 expression was increased. Further investigation showed that overexpression of TIPE2 effectively inhibited MDR1 expression and greatly sensitized osteosarcoma cells to cis-platin, both in vivo and in vitro. Mechanistically, TIPE2 inhibited the transcription of the MDR1 promoter by interfering with the TAK1-NF-κB and -AP-1 pathways. Overall, our results elucidated for the first time that TIPE2 sensitizes osteosarcoma cells to cis-platin through downregulation of MDR1 and may be a novel target in osteosarcoma therapy.
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Affiliation(s)
- Peiqing Zhao
- Department of Gynecologic Oncology, the Fourth Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu, China; Center of Translational Medicine, Zibo Central Hospital, Zibo, China.
| | - Sujie Wang
- Department of Oncology, Zibo Central Hospital, Zibo, China
| | - Jie Jiang
- Department of Clinical Laboratory, Yantai Affiliated Hospital of Binzhou Medical University, China
| | - Hong Liu
- Center of Translational Medicine, Zibo Central Hospital, Zibo, China
| | - Xiaolan Zhu
- Department of Gynecologic Oncology, the Fourth Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu, China
| | - Ning Zhao
- Center of Translational Medicine, Zibo Central Hospital, Zibo, China
| | - Jigang Li
- Center of Translational Medicine, Zibo Central Hospital, Zibo, China
| | - Yingchun Yin
- Center of Translational Medicine, Zibo Central Hospital, Zibo, China
| | - Xiaoyan Pan
- Center of Translational Medicine, Zibo Central Hospital, Zibo, China
| | - Xiuzhen Yang
- Center of Translational Medicine, Zibo Central Hospital, Zibo, China
| | - Jianping Guo
- Center of Translational Medicine, Zibo Central Hospital, Zibo, China
| | - Wenlin Xu
- Department of Gynecologic Oncology, the Fourth Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu, China.
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5
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Schulze S, Reinhardt S, Freese C, Schmitt U, Endres K. Identification of trichlormethiazide as a Mdr1a/b gene expression enhancer via a dual secretion-based promoter assay. Pharmacol Res Perspect 2015; 3:e00109. [PMID: 25692026 PMCID: PMC4317239 DOI: 10.1002/prp2.109] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 10/07/2014] [Indexed: 11/29/2022] Open
Abstract
Transporters of the ATP-binding cassette (ABC) family such as MDR1 play a pivotal role in persistence of brain homeostasis by contributing to the strict permeability properties of the blood–brain barrier. This barrier on one hand compromises treatment of central nervous system diseases by restricting access of drugs; on the other hand, an impaired or altered function of barrier building cells has been described in neurological disorders. The latter might contribute to increased vulnerability of the brain under pathological conditions or even enforce pathogenesis. Here, we present a novel approach for a systematic examination of drug impact on Mdr1 gene expression by establishing a dual reporter gene assay for the murine upstream core promoters of Mdr1a and b. We validated the time-resolved assay in comparison with single reporter gene constructs and applied it to analyze effects of a Food and Drug Administration (FDA)-approved drug library consisting of 627 substances. The chemo-preventive synthetic dithiolethione oltipraz was reidentified with our assay as an already known inducer of Mdr1 gene expression. Together with two newly characterized modifiers – gemcitabine and trichlormethiazide – we prove our findings in a blood–brain barrier culture model as well as in wild-type and Mdr1 knockout mice. In sum, we could demonstrate that our dual reporter gene assay delivers results, which also persist in the living animal and consequently is applicable for further analysis and prediction of Mdr1 regulation in vivo.
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Affiliation(s)
- Sarina Schulze
- Clinic of Psychiatry and Psychotherapy, University Medical Center Johannes Gutenberg University Mainz, Germany
| | - Sven Reinhardt
- Clinic of Psychiatry and Psychotherapy, University Medical Center Johannes Gutenberg University Mainz, Germany
| | - Christian Freese
- REPAIR-lab, Institute of Pathology, University Medical Center of the Johannes Gutenberg University Mainz and European Institute of Excellence on Tissue Engineering and Regenerative Medicine Mainz, Germany
| | - Ulrich Schmitt
- Clinic of Psychiatry and Psychotherapy, University Medical Center Johannes Gutenberg University Mainz, Germany
| | - Kristina Endres
- Clinic of Psychiatry and Psychotherapy, University Medical Center Johannes Gutenberg University Mainz, Germany
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6
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Sike Á, Nagy E, Vedelek B, Pusztai D, Szerémy P, Venetianer A, Boros IM. mRNA levels of related Abcb genes change opposite to each other upon histone deacetylase inhibition in drug-resistant rat hepatoma cells. PLoS One 2014; 9:e84915. [PMID: 24409311 PMCID: PMC3883685 DOI: 10.1371/journal.pone.0084915] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 11/27/2013] [Indexed: 11/18/2022] Open
Abstract
The multidrug-resistant phenotype of tumor cells is acquired via an increased capability of drug efflux by ABC transporters and causes serious problems in cancer treatment. With the aim to uncover whether changes induced by epigenetic mechanisms in the expression level of drug transporter genes correlates with changes in the drug resistance phenotypes of resistant cells, we studied the expression of drug transporters in rat hepatoma cell lines. We found that of the three major rat ABC transporter genes Abcb1a, Abcb1b and Abcc1 the activity of only Abcb1b increased significantly in colchicine-selected, drug-resistant cells. Increased transporter expression in drug-resistant cells results primarily from transcriptional activation. A change in histone modification at the regulatory regions of the chromosomally adjacent Abcb1a and Abcb1b genes differentially affects the levels of corresponding mRNAs. Transcriptional up- and down-regulation accompany an increase in acetylation levels of histone H3 lysine 9 at the promoter regions of Abcb1b and Abcb1a, respectively. Drug efflux activity, however, does not follow tightly the transcriptional activity of drug transporter genes in hepatoma cells. Our results point out the need for careful analysis of cause-and-effect relationships between changes in histone modification, drug transporter expression and drug resistance phenotypes.
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Affiliation(s)
- Ádám Sike
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary
| | - Enikő Nagy
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary
| | - Balázs Vedelek
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary
| | - Dávid Pusztai
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary
| | | | - Anikó Venetianer
- Institute of Genetics, Biological Research Center, Szeged, Hungary
| | - Imre M. Boros
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary
- Institute of Biochemistry, Biological Research Center, Szeged, Hungary
- * E-mail:
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7
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Gu L, Chen J, Synold TW, Forman BM, Kane SE. Bioimaging real-time PXR-dependent mdr1a gene regulation in mdr1a.fLUC reporter mice. J Pharmacol Exp Ther 2013; 345:438-45. [PMID: 23532932 PMCID: PMC3657110 DOI: 10.1124/jpet.113.203562] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 03/25/2013] [Indexed: 11/22/2022] Open
Abstract
The MDR1 gene encodes P-glycoprotein, a transmembrane drug efflux transporter that confers multidrug resistance in cancer cells and affects drug pharmacokinetics by virtue of its expression in the liver, kidney, and colon. Nuclear receptors human steroid and xenobiotic receptor (SXR) and constitutive androstane receptor (CAR) are possible master regulators of xenobiotic-inducible MDR1 expression in drug processing organs, but the mechanism of MDR1 regulation has yet to be directly demonstrated in vivo. Moreover, it has previously been impossible to determine the sustained or cumulative effect of repeated doses of xenobiotics on in vivo MDR1 expression. We previously reported a mouse model containing firefly luciferase (fLUC) knocked into the mdr1a genomic locus, allowing noninvasive bioimaging of intestinal mdr1a gene expression in live animals. In the current study, we crossed mdr1a.fLUC mice into the pxr knockout (pxr(-/-)) genetic background and injected mice with pregnenolone-16α-carbonitrile (PCN), a strong mouse pregnane X receptor (PXR) ligand, and two therapeutically relevant taxanes, paclitaxel and docetaxel. All three agents induced mdr1a.fLUC expression (bioluminescence), but only PCN and docetaxel appeared to act primarily via PXR. Luminescence returned to baseline by 24-48 hours after drug injection and was reinducible over two additional rounds of drug dosing in pxr(+/+) mice. TCPOBOP, a CAR ligand, modestly induced mdr1a.fLUC in pxr(+/+) and pxr(-/-) strains, consistent with CAR's minor role in mdr1a regulation. Collectively, these results demonstrate that the mdr1a.fLUC bioimaging model can capture changes in mdr1 gene expression under conditions of repeated xenobiotic treatment in vivo and that it can be used to probe the mechanism of gene regulation in response to different xenobiotic agents.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B/drug effects
- ATP Binding Cassette Transporter, Subfamily B/genetics
- Animals
- Antineoplastic Agents, Phytogenic/pharmacology
- Constitutive Androstane Receptor
- Docetaxel
- Fatty Acids, Monounsaturated/pharmacology
- Gene Expression/drug effects
- Genes, Reporter/drug effects
- Genes, Reporter/genetics
- Humans
- Image Processing, Computer-Assisted
- Intestinal Mucosa/metabolism
- Ligands
- Luciferases/genetics
- Luminescent Proteins/biosynthesis
- Mice
- Mice, Knockout
- Paclitaxel/pharmacology
- Pregnane X Receptor
- Pyridines/pharmacology
- Quaternary Ammonium Compounds/pharmacology
- Receptors, Cytoplasmic and Nuclear/metabolism
- Receptors, Steroid/drug effects
- Receptors, Steroid/genetics
- Taxoids/pharmacology
- Xenobiotics/pharmacology
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Affiliation(s)
- Long Gu
- Department of Cancer Biology, Beckman Research Institute at City of Hope, Duarte, California, USA
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Manoharlal R, Gorantala J, Sharma M, Sanglard D, Prasad R. PAP1 [poly(A) polymerase 1] homozygosity and hyperadenylation are major determinants of increased mRNA stability of CDR1 in azole-resistant clinical isolates of Candida albicans. MICROBIOLOGY-SGM 2009; 156:313-326. [PMID: 19910410 DOI: 10.1099/mic.0.035154-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Using genetically matched azole-susceptible (AS) and azole-resistant (AR) clinical isolates of Candida albicans, we recently demonstrated that CDR1 overexpression in AR isolates is due to its enhanced transcriptional activation and mRNA stability. This study examines the molecular mechanisms underlying enhanced CDR1 mRNA stability in AR isolates. Mapping of the 3' untranslated region (3' UTR) of CDR1 revealed that it was rich in adenylate/uridylate (AU) elements, possessed heterogeneous polyadenylation sites, and had putative consensus sequences for RNA-binding proteins. Swapping of heterologous and chimeric lacZ-CDR1 3' UTR transcriptional reporter fusion constructs did not alter the reporter activity in AS and AR isolates, indicating that cis-acting sequences within the CDR1 3' UTR itself are not sufficient to confer the observed differential mRNA decay. Interestingly, the poly(A) tail of the CDR1 mRNA of AR isolates was approximately 35-50 % hyperadenylated as compared with AS isolates. C. albicans poly(A) polymerase (PAP1), responsible for mRNA adenylation, resides on chromosome 5 in close proximity to the mating type-like (MTL) locus. Two different PAP1 alleles, PAP1-a/PAP1-alpha, were recovered from AS (MTL-a/MTL-alpha), while a single type of PAP1 allele (PAP1-alpha) was recovered from AR isolates (MTL-alpha/MTL-alpha). Among the heterozygous deletions of PAP1-a (Deltapap1-a/PAP1-alpha) and PAP1-alpha (PAP1-a/Deltapap1-alpha), only the former led to relatively enhanced drug resistance, to polyadenylation and to transcript stability of CDR1 in the AS isolate. This suggests a dominant negative role of PAP1-a in CDR1 transcript polyadenylation and stability. Taken together, our study provides the first evidence, to our knowledge, that loss of heterozygosity at the PAP1 locus is linked to hyperadenylation and subsequent increased stability of CDR1 transcripts, thus contributing to enhanced drug resistance.
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Affiliation(s)
- Raman Manoharlal
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Jyotsna Gorantala
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Monika Sharma
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Dominique Sanglard
- Institute of Microbiology, University Hospital Lausanne, Lausanne CH-1011, Switzerland
| | - Rajendra Prasad
- Membrane Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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9
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Hesselson SE, Matsson P, Shima JE, Fukushima H, Yee SW, Kobayashi Y, Gow JM, Ha C, Ma B, Poon A, Johns SJ, Stryke D, Castro RA, Tahara H, Choi JH, Chen L, Picard N, Sjödin E, Roelofs MJE, Ferrin TE, Myers R, Kroetz DL, Kwok PY, Giacomini KM. Genetic variation in the proximal promoter of ABC and SLC superfamilies: liver and kidney specific expression and promoter activity predict variation. PLoS One 2009; 4:e6942. [PMID: 19742321 PMCID: PMC2735003 DOI: 10.1371/journal.pone.0006942] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Accepted: 08/05/2009] [Indexed: 12/11/2022] Open
Abstract
Membrane transporters play crucial roles in the cellular uptake and efflux of an array of small molecules including nutrients, environmental toxins, and many clinically used drugs. We hypothesized that common genetic variation in the proximal promoter regions of transporter genes contribute to observed variation in drug response. A total of 579 polymorphisms were identified in the proximal promoters (−250 to +50 bp) and flanking 5′ sequence of 107 transporters in the ATP Binding Cassette (ABC) and Solute Carrier (SLC) superfamilies in 272 DNA samples from ethnically diverse populations. Many transporter promoters contained multiple common polymorphisms. Using a sliding window analysis, we observed that, on average, nucleotide diversity (π) was lowest at approximately 300 bp upstream of the transcription start site, suggesting that this region may harbor important functional elements. The proximal promoters of transporters that were highly expressed in the liver had greater nucleotide diversity than those that were highly expressed in the kidney consistent with greater negative selective pressure on the promoters of kidney transporters. Twenty-one promoters were evaluated for activity using reporter assays. Greater nucleotide diversity was observed in promoters with strong activity compared to promoters with weak activity, suggesting that weak promoters are under more negative selective pressure than promoters with high activity. Collectively, these results suggest that the proximal promoter region of membrane transporters is rich in variation and that variants in these regions may play a role in interindividual variation in drug disposition and response.
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Affiliation(s)
- Stephanie E. Hesselson
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Pär Matsson
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - James E. Shima
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Hisayo Fukushima
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Sook Wah Yee
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Yuya Kobayashi
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Jason M. Gow
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Connie Ha
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Benjamin Ma
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Annie Poon
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Susan J. Johns
- Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Doug Stryke
- Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Richard A. Castro
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Harunobu Tahara
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Ji Ha Choi
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Ligong Chen
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Nicolas Picard
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Elin Sjödin
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Maarke J. E. Roelofs
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Thomas E. Ferrin
- Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
| | - Richard Myers
- Department of Genetics, Stanford University School of Medicine, Stanford, California, United States of America
| | - Deanna L. Kroetz
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
| | - Pui-Yan Kwok
- Cardiovascular Research Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Kathleen M. Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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10
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Pajic M, Iyer JK, Kersbergen A, van der Burg E, Nygren AOH, Jonkers J, Borst P, Rottenberg S. Moderate increase in Mdr1a/1b expression causes in vivo resistance to doxorubicin in a mouse model for hereditary breast cancer. Cancer Res 2009; 69:6396-404. [PMID: 19654309 DOI: 10.1158/0008-5472.can-09-0041] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have found previously that acquired doxorubicin resistance in a genetically engineered mouse model for BRCA1-related breast cancer was associated with increased expression of the mouse multidrug resistance (Mdr1) genes, which encode the drug efflux transporter ATP-binding cassette B1/P-glycoprotein (P-gp). Here, we show that even moderate increases of Mdr1 expression (as low as 5-fold) are sufficient to cause doxorubicin resistance. These moderately elevated tumor P-gp levels are below those found in some normal tissues, such as the gut. The resistant phenotype could be completely reversed by the third-generation P-gp inhibitor tariquidar, which provides a useful strategy to circumvent this type of acquired doxorubicin resistance. The presence of MDR1A in drug-resistant tumors with a moderate increase in Mdr1a transcripts could be shown with a newly generated chicken antibody against a mouse P-gp peptide. Our data show the usefulness of realistic preclinical models to characterize levels of Mdr1 gene expression that are sufficient to cause resistance.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B/antagonists & inhibitors
- ATP Binding Cassette Transporter, Subfamily B/genetics
- ATP Binding Cassette Transporter, Subfamily B/metabolism
- Animals
- Antibiotics, Antineoplastic/pharmacology
- Antibiotics, Antineoplastic/therapeutic use
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Disease Models, Animal
- Doxorubicin/pharmacology
- Doxorubicin/therapeutic use
- Drug Resistance, Neoplasm/genetics
- Female
- Gene Expression Regulation, Neoplastic/physiology
- Genes, BRCA1
- Genes, p53
- Humans
- Mice
- Mice, Knockout
- Quinolines/pharmacology
- Tumor Burden
- Up-Regulation/physiology
- ATP-Binding Cassette Sub-Family B Member 4
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Affiliation(s)
- Marina Pajic
- Division of Molecular Biology and Centre for Biomedical Genetics, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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11
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Summerfield SG, Jeffrey P. In vitro prediction of brain penetration – a case for free thinking? Expert Opin Drug Discov 2006; 1:595-607. [DOI: 10.1517/17460441.1.6.595] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Scott G Summerfield
- Drug Metabolism and Pharmacokinetics, Neurology and Gastrointestinal Centre of Excellence for Drug discovery, New Frontiers Science Park, Third Avenue, Harlow, Essex, CM19 5AW, United Kingdom
| | - Phil Jeffrey
- Drug Metabolism and Pharmacokinetics, Neurology and Gastrointestinal Centre of Excellence for Drug discovery, New Frontiers Science Park, Third Avenue, Harlow, Essex, CM19 5AW, United Kingdom
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12
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Booth-Genthe CL, Louie SW, Carlini EJ, Li B, Leake BF, Eisenhandler R, Hochman JH, Mei Q, Kim RB, Rushmore TH, Yamazaki M. Development and characterization of LLC-PK1 cells containing Sprague–Dawley rat Abcb1a (Mdr1a): Comparison of rat P-glycoprotein transport to human and mouse. J Pharmacol Toxicol Methods 2006; 54:78-89. [PMID: 16545584 DOI: 10.1016/j.vascn.2005.12.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2005] [Accepted: 12/21/2005] [Indexed: 10/24/2022]
Abstract
INTRODUCTION P-glycoprotein is localized in numerous tissues throughout the body and plays an important role in the disposition of many xenobiotics. The contribution of P-glycoprotein-mediated drug transport is being evaluated in early drug discovery stages, particularly for compounds targeted to the central nervous system, using in vitro tools including cell lines expressing P-glycoprotein. Previous work in our laboratory suggests there are species differences in P-glycoprotein transport activity between humans and animals. The rat Abcb1a form of P-glycoprotein (formerly known as Mdr1a), the predominate isoform in the brain, has not been described in a functional cell system. Here, we describe the development and characterization of LLC-PK1 cells expressing rat Abcb1. METHODS We cloned rat Abcb1a and generated a stable LLC-PK1 cell line. Expression and function of the cells were evaluated by immunoblot analysis, cytotoxicity analysis, cellular accumulation assays, and transcellular transport of probe substrates. The transport ratios of structurally diverse compounds obtained from parental cells or cells stably transfected with human ABCB1, mouse Abcb1a or rat Abcb1a were compared. RESULTS Two forms of rat Abcb1a were cloned from Sprague-Dawley cDNA that differ by six amino acids and a base pair deletion. The intact form was stably transfected in LLC-PK1 cells. Immunoblot analysis demonstrated expression of the protein. The cells demonstrated P-glycoprotein-mediated function by directional transport of dexamethasone, ritonavir, and vinblastine in a transwell assay that was inhibited in the presence of cyclosporin A, verapamil, or quinidine. Likewise, the cells showed reduced cellular accumulation of Rh123 by FACS analysis that was reversed in the presence of cyclosporin A. These cells showed >or=350-fold resistance to colchicine, doxorubicin, vinblastine, and taxol and were sensitized in the presence of verapamil or cyclosporin A. Of 179 chemically diverse compounds evaluated, approximately 20% of the compounds evaluated were predicted to be substrates in one species but not in other species. DISCUSSION Taken together, these data suggest these cells will be useful for evaluation of rat Abcb1a-mediated transport and for evaluation of species-specific P-glycoprotein-mediated transport.
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Bauer B, Hartz AMS, Fricker G, Miller DS. Modulation of p-glycoprotein transport function at the blood-brain barrier. Exp Biol Med (Maywood) 2005; 230:118-27. [PMID: 15673560 DOI: 10.1177/153537020523000206] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The central nervous system (CNS) effects of many therapeutic drugs are blunted because of restricted entry into the brain. The basis for this poor permeability is the brain capillary endothelium, which comprises the blood-brain barrier. This tissue exhibits very low paracellular (tight-junctional) permeability and expresses potent, multispecific, drug export pumps. Together, these combine to limit use of pharmacotherapy to treat CNS disorders such as brain cancer and bacterial or viral infections. Of all the xenobiotic efflux pumps highly expressed in brain capillary endothelial cells, p-glycoprotein handles the largest fraction of commonly prescribed drugs and thus is an obvious target for manipulation. Here we review recent studies focused on understanding the mechanisms by which p-glycoprotein activity in the blood-brain barrier can be modulated. These include (i) direct inhibition by specific competitors, (ii) functional modulation, and (iii) transcriptional modulation. Each has the potential to specifically reduce p-glycoprotein function and thus selectively increase brain permeability of p-glycoprotein substrates.
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Affiliation(s)
- Björn Bauer
- Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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14
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Muredda M, Nunoya KI, Burtch-Wright RA, Kurz EU, Cole SPC, Deeley RG. Cloning and Characterization of the Murine and Rat mrp1 Promoter Regions. Mol Pharmacol 2003; 64:1259-69. [PMID: 14573776 DOI: 10.1124/mol.64.5.1259] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ATP-binding cassette transporter multidrug resistance protein 1 (MRP1) confers resistance to a number of clinically important chemotherapeutic agents. The proximal promoter region of MRP1 is GC-rich and contains binding sites for members of the Sp1 family of trans-acting factors that seem to be important for basal expression. As an approach to searching for other elements that may contribute to expression, we have sequenced and functionally compared the promoters of the murine and rat mrp1 genes with that of the human gene. All three promoters are GC-rich, TATA-less, and CAAT-less. Conservation of sequence between rodent and human promoters is limited to a proximal region of 100 nucleotides containing binding sites for members of the Sp1 family and a putative activator protein-1 element. The 5'-untranslated region (UTR) of human MRP1 contains an insertion of approximately 160 nucleotides comprising a GCC-triplet repeat and a GC-rich tandem repeat that is absent from the rodent sequences. Transient transfection analyses demonstrated that the conserved GC-boxes of all three genes are the major determinants of basal activity. Based on electrophoretic mobility shift assays, each GC-box can be bound by Sp1 or Sp3. Unlike the rodent genes, the human MRP1 5'UTR also binds Sp1 but not Sp3, and the human promoter retains substantial activity even in the absence of the conserved GC-boxes. Finally, we show that the tumor suppressor protein p53 can repress the human and rodent promoters by a mechanism that is independent of the Sp1 elements.
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Affiliation(s)
- Mario Muredda
- Queen's University Cancer Research Institute, Botterell Hall Room A315C, Queen's University, Kingston, Ontario, Canada K7L 3N6
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15
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López-Camarillo C, Luna-Arias JP, Marchat LA, Orozco E. EhPgp5 mRNA stability is a regulatory event in the Entamoeba histolytica multidrug resistance phenotype. J Biol Chem 2003; 278:11273-11280. [PMID: 12556531 DOI: 10.1074/jbc.m211757200] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The multidrug resistance (MDR) phenotype in Entamoeba histolytica is characterized by the overexpression of the EhPgp5 gene in trophozoites grown in high drug concentrations. Here we evaluated the role of EhPgp5 mRNA stability on MDR using actinomycin D. EhPgp5 mRNA from trophozoites growing without emetine had a half-life of 2.1 h, which augmented to 3.1 h in cells cultured with 90 microM and to 7.8 h with 225 microM emetine. Polyadenylation sites were detected at 118-, 156-, and 189-nucleotide (nt) positions of the EhPgp5 mRNA 3'-untranslated region. Interestingly, trophozoites grown with 225 microM emetine exhibited an extra polyadenylation site at 19 nt. The 3'-untranslated region sequence is AU-rich and has putative consensus sequences for RNA-binding proteins. We detected a RNA-protein complex in a region that contains a polypyrimidine tract (142-159 nt) and a cytoplasmic polyadenylation element (146-154 nt). A longer poly(A) tail in the EhPgp5 mRNA was seen in trophozoites grown with 225 microM emetine. Emetine stress may affect factors involved in mRNA turnover, including polyadenylation/deadenylation proteins, which could induce changes in the EhPgp5 mRNA half-life and poly(A) tail length. Novel evidence on mechanisms participating in E. histolytica MDR phenotype is provided.
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Affiliation(s)
- César López-Camarillo
- Programa de Biomedicina Molecular, Escuela Nacional de Medicina y Homeopatia del Instituto Politécnico Nacional, CP 07300, México, Distrito Federal
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16
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Begley DJ, Brightman MW. Structural and functional aspects of the blood-brain barrier. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2003; 61:39-78. [PMID: 14674608 DOI: 10.1007/978-3-0348-8049-7_2] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- David J Begley
- Centre for Neuroscience Research, Kings College London, Hodgkin Building, Guy's Campus, London SE1 1UL, UK.
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17
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Salerno M, Przewloka T, Fokt I, Priebe W, Garnier-Suillerot A. Preferential efflux by P-glycoprotein, but not MRP1, of compounds containing a free electron donor amine. Biochem Pharmacol 2002; 63:1471-9. [PMID: 11996888 DOI: 10.1016/s0006-2952(02)00895-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Multidrug resistance (MDR) in model systems is known to be conferred by two different integral proteins, the 170-kDa P-glycoprotein (P-gp) and the 190-kDa multidrug resistance-associated protein (MRP1), both of which pump drugs out of MDR cells. The presence of a nitrogen atom, charged at physiological pH, has frequently been considered to be a hallmark of P-gp substrates and inhibitors. The present study was aimed at investigating the role of nitrogen in the ability of the pump to recognise substrate. We measured the kinetics of active efflux of seven new anthracycline derivatives in P-gp-expressing K562/ADR cells and in MRP1-expressing GLC4/ADR cells. Six of these compounds represent analogues of daunorubicin in which the amino sugar nitrogen is bound to an amino- or a nitro-substituted benzyl moiety, the seventh is a doxorubicin derivative in which benzyl group is bound with 4'-oxygen. We found that the compounds with a nitro group on the benzyl ring were poor substrates for P-gp despite the presence of a secondary amine that can be protonated. In contrast, compounds that have a free amino group were very good substrates even though this amine is not protonated in the pH range studied (pK approximately 3). These results show that the nitrogen atom does not interact with P-gp in a charged form but rather as an electron donating group.
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Affiliation(s)
- Milena Salerno
- Laboratoire de Physicochimie Biomoléculaire et Cellulaire, UMR 7033, Université Paris Nord, 74 Rue Marcel Cachin, 93017 Bobigny, France
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18
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Gigliozzi A, Fraioli F, Sundaram P, Lee J, Mennone A, Alvaro D, Boyer JL. Molecular identification and functional characterization of Mdr1a in rat cholangiocytes. Gastroenterology 2000; 119:1113-22. [PMID: 11040198 DOI: 10.1053/gast.2000.18156] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
BACKGROUND & AIMS The multidrug resistance P-glycoprotein 170 gene products (mdr1a and 1b) are glycosylated plasma membrane proteins that function as adenosine triphosphate-dependent transmembrane export pumps for lipophilic xenobiotics of widely different structure. We assessed whether these P-glycoproteins are functionally expressed in cholangiocytes. METHODS A reverse-transcription polymerase chain reaction was performed on RNA from a normal rat cholangiocyte cell line using mdr1-specific primers. Northern and Western blot analyses were performed on cholangiocytes immunoisolated from 2-week bile duct-ligated rats and cholangiocytes and isolated cholangiocyte membrane subfractions, respectively. Functional assays were performed in isolated bile duct units from bile duct-ligated rats and incubated with rhodamine 123, a P-glycoprotein substrate, with or without the P-glycoprotein inhibitors verapamil or GF120918. RESULTS A 400-base pair fragment with 99% homology to the cytosolic domain of rat intestinal mdr1a (5' 1953-2350 3') was identified that hybridized to a 5.2-kilobase RNA transcript in a normal rat cholangiocyte cell line, isolated rat cholangiocytes, and ileum. Western analysis localized mdr1 to the apical membrane of cholangiocytes. Confocal microscopy showed active secretion of rhodamine 123 into the lumen of isolated bile duct units that was abolished by vanadate and P-glycoprotein competitive antagonists, verapamil and GF120918, in a dose-dependent manner. CONCLUSIONS These findings provide the first molecular and functional evidence for the expression of mdr1a on the luminal membrane of cholangiocytes, where it may have a protective role.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B/analysis
- ATP Binding Cassette Transporter, Subfamily B/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism
- ATP-Binding Cassette Transporters/analysis
- ATP-Binding Cassette Transporters/genetics
- Acridines/pharmacology
- Animals
- Bile Ducts/cytology
- Bile Ducts/drug effects
- Bile Ducts/physiology
- Cell Division
- Cell Membrane/drug effects
- Cell Membrane/physiology
- Cytosol/physiology
- Drug Resistance, Multiple
- In Vitro Techniques
- Isoquinolines/pharmacology
- Kinetics
- Male
- Microscopy, Confocal
- RNA, Messenger/analysis
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
- Rhodamine 123
- Tetrahydroisoquinolines
- Transcription, Genetic/drug effects
- Vanadates/pharmacology
- Verapamil/pharmacology
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Affiliation(s)
- A Gigliozzi
- Department of Internal Medicine and Liver Center, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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19
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Okai Y, Nakamura N, Matsushiro H, Kato H, Setoguchi A, Yazawa M, Okuda M, Watari T, Hasegawa A, Tsujimoto H. Molecular analysis of multidrug resistance in feline lymphoma cells. Am J Vet Res 2000; 61:1122-7. [PMID: 10976746 DOI: 10.2460/ajvr.2000.61.1122] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate the mechanism of multidrug resistance in feline lymphoma cell lines. SAMPLE POPULATION A feline lymphoma cell line (FT-1) and its adriamycin (ADM)-resistant subline (FT-1/ADM). PROCEDURES The FT-1 cell line was cultivated in the presence of a gradually increasing concentration of ADM to generate its ADM-resistant subline (FT-1/ADM). Susceptibility of cells from the parental FT-1 cell line and the FT-1/ADM subline to antineoplastic drugs was determined. From the complementary DNA (cDNA) template of FT-1/ADM cells, feline MDR1 cDNA was amplified by use of polymerase chain reaction (PCR) and sequenced. Reverse transcription (RT)-PCR and Western blot analyses were performed to assess expression of the MDR1 gene and P-glycoprotein (P-gp) in FT-1/ADM cells, compared with that in FT-1 cells. RESULTS A drug sensitivity assay revealed that FT-1/ADM cells were much more resistant to ADM and vincristine than the parental FT-1 cells. The feline MDR7 cDNA amplified by use of PCR was 3,489 base pairs long, corresponding to approximately 90% of the whole open reading frame of human MDR1 cDNA; its amino acid sequence was 91.5, 87.0, and 79.4% identical to that of human MDR1, mouse mdr1a, and mdr1b cDNA, respectively. By RT-PCR analysis, expression of MDR1 messenger RNA was clearly detected in FT-1/ADM cells but not in the parental FT-1 cells. Western blot analysis also revealed the expression of P-gp encoded by the MDR1 gene in FT-1/ADM cells but not in FT-1 cells. CONCLUSIONS The basic structure of the feline MDR1 gene was essentially the same as that of multidrug-resistance genes of other species. Expression of P-gp appeared to be one of the mechanisms responsible for the development of multidrug resistance in feline lymphoma cell lines in vitro.
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Affiliation(s)
- Y Okai
- Department of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, University of Tokyo, Japan
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20
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Meijer DK, Smit JW, Hooiveld GJ, van Montfoort JE, Jansen PL, Müller M. The molecular basis for hepatobiliary transport of organic cations and organic anions. PHARMACEUTICAL BIOTECHNOLOGY 2000; 12:89-157. [PMID: 10742973 DOI: 10.1007/0-306-46812-3_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- D K Meijer
- Department of Pharmacokinetics and Drug Delivery, Groningen University Institute for Drug Exploration (GUIDE), The Netherlands
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21
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H-Ferritin Subunit Overexpression in Erythroid Cells Reduces the Oxidative Stress Response and Induces Multidrug Resistance Properties. Blood 1999. [DOI: 10.1182/blood.v94.10.3593.422k26_3593_3603] [Citation(s) in RCA: 149] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The labile iron pool (LIP) of animal cells has been implicated in cell iron regulation and as a key component of the oxidative-stress response. A major mechanism commonly implied in the downregulation of LIP has been the induced expression of ferritin (FT), particularly the heavy subunits (H-FT) that display ferroxidase activity. The effects of H-FT on LIP and other physiological parameters were studied in murine erythroleukemia (MEL) cells stably transfected with H-FT subunits. Clones expressing different levels of H-FT displayed similar concentrations of total cell iron (0.3 ± 0.1 mmol/L) and of reduced/total glutathione. However, with increasing H-FT levels the cells expressed lower levels of LIP and reactive oxygen species (ROS) and ensuing cell death after iron loads and oxidative challenges. These results provide direct experimental support for the alleged roles of H-FT as a regulator of labile cell iron and as a possible attenuator of the oxidative cell response. H-FT overexpression was of no apparent consequence to the cellular proliferative capacity. However, concomitant with the acquisition of iron and redox regulatory capacities, the H-FT–transfectant cells commensurately acquired multidrug resistance (MDR) properties. These properties were identified as increased expression of MDR1 mRNA (by reverse transcription polymerase chain reaction [RT-PCR]), P-glycoprotein (Western immunoblotting), drug transport activity (verapamil-sensitive drug efflux), and drug cytotoxicity associated with increased MDR1 or PgP. Although enhanced MDR expression per se evoked no significant changes in either LIP levels or ROS production, it might be essential for the survival of H-FT transfectants, possibly by expediting the export of cell-generated metabolites.
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22
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Parissenti AM, Gannon BR, Villeneuve DJ, Kirwan-rhude AF, Chadderton A, Glück S. Lack of modulation of MDR1 gene expression by dominant inhibition of cAMP-dependent protein kinase in doxorubicin-resistant MCF-7 breast cancer cells. Int J Cancer 1999; 82:893-900. [PMID: 10446459 DOI: 10.1002/(sici)1097-0215(19990909)82:6<893::aid-ijc20>3.0.co;2-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The drug transporter P-glycoprotein (P-gp) appears to play an important role in the ability of tumor cells to evade killing by chemotherapeutic agents. Using pharmacological inhibitors of cAMP-dependent protein kinase (PKA), it has been suggested that, similar to rodent model systems, the human P-gp gene (MDR1) is also under PKA-dependent control and that PKA inhibition may prove useful in reducing drug resistance in human cancer cells. To test this hypothesis, we stably transformed doxorubicin (Adriamycin)-resistant human MCF-7 breast cancer cells (MCF-7(ADR)) with a vector that inhibits PKA activity by inducing over-expression of mutant type Ialpha PKA regulatory (RIalpha) subunits. Two transformants (MCF-7(ADR-A) and MCF-7(ADR-B)) were found to express mutant RIalpha subunits and to possess markedly reduced PKA activity; another transformant (MCF-7(ADR-9)) lacked mutant RIalpha subunit expression and exhibited no inhibition of PKA activity. In contrast with findings in Chinese hamster ovary and Y1 adrenal cells, P-gp levels and cellular sensitivity to drugs which are P-gp substrates were unchanged in the PKA-inhibited transformants, suggesting that P-gp expression and function are not under PKA-dependent control in MCF-7(ADR) cells. Growth and saturation densities of the cell lines were highly correlated with level of PKA catalytic activity, suggesting that PKA inhibition may prove useful in inhibiting growth of breast tumor cells, even upon establishment of resistance to doxorubicin. However, our results challenge current proposals that drug sensitivity in P-gp-expressing human tumor cells may be restored by blocking MDR1 gene expression through inhibition of PKA activity.
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Affiliation(s)
- A M Parissenti
- Department of Research, Northeastern Ontario Regional Cancer Centre, Sudbury, Ontario, Canada.
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23
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Li M, Hurren R, Zastawny RL, Ling V, Buick RN. Regulation and expression of multidrug resistance (MDR) transcripts in the intestinal epithelium. Br J Cancer 1999; 80:1123-31. [PMID: 10376961 PMCID: PMC2362371 DOI: 10.1038/sj.bjc.6690475] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A paucity of information exists on the regulation of gene expression in the undifferentiated intestine. The intestinal epithelium is one of the few normal tissues expressing the multidrug resistance (MDR) genes that confer the multidrug resistant phenotype to a variety of tumours. Expression of mdr1a has been observed in the primitive rat intestinal epithelial cell line, IEC-18. It is hypothesized that characterization of MDR gene expression in IEC-18 cells will provide insight into gene regulation in undifferentiated intestinal cells. A series of hamster mdr1a promoter deletion constructs was studied in IEC-18 and a region with 12-13-fold enhancer activity was identified. This region was shown to function in an orientation- and promoter context-independent manner, specifically in IEC-18 cells. Unexpectedly, Northern probing revealed a greater expression of mdr1b than mdr1a in IEC-18 cells. A quantitative reverse transcription polymerase chain reaction assay was used to compare the relative expression of MDR genes in IEC cells, fetal intestine, and in the undifferentiated and differentiated components of adult intestinal epithelium. MDR transcript levels in IEC cells were found to resemble those of fetal intestine and small intestinal crypts, where a conversion from mixed mdr1a/mdr1b to predominantly mdr1a expression occurs as cells mature. This work describes two contributions to the field of gene regulation in the undifferentiated intestine--first, the initial characterization of a putative mdr1a enhancer region with specificity for primitive intestinal cells and secondly, the first report of mdr1b detection in the intestine and its expression in primitive cell types.
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Affiliation(s)
- M Li
- Ontario Cancer Institute/Princess Margaret Hospital and Department of Medical Biophysics, University of Toronto, Canada
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24
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Affiliation(s)
- S Volkman
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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25
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Pérez DG, Gómez C, López-Bayghen E, Tannich E, Orozco E. Transcriptional analysis of the EhPgp5 promoter of Entamoeba histolytica multidrug-resistant mutant. J Biol Chem 1998; 273:7285-92. [PMID: 9516422 DOI: 10.1074/jbc.273.13.7285] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We report here the cloning and transcriptional characterization of the EhPgp5 multidrug resistance gene promoter isolated from the drug-resistant clone C2 of Entamoeba histolytica. The EhPgp5 promoter has the TATA-like motif at -31 base pairs; transcription initiates three nucleotides upstream from the ATG in trophozoites grown in 225 microM emetine (clone C2(225)), whereas in those grown without the drug (clone C2) a product with no open reading frame was detected. The promoter was active in transfected clone C2 trophozoites, its activity increased when trophozoites were cultured in 40 microM emetine, while it was turned off in the drug-sensitive clone A. The first -235 base pair kept full promoter activity, suggesting that it has important drug responsive elements. Gel shift assays detected the complex Ib in clone C2, which was augmented in clone C2(225). Competition experiments suggested that complex Ib may be constituted by HOX and AP-1 like factors in clone C2, whereas in clone C2(225), complex Ib was only competed by the HOX sequence. Complexes Ie, detected in clones A and C2 but not in C2(225), and Ia, present in all clones, were competed by the TATA box oligonucleotide. Our results suggest that proteins forming complexes Ib and Ie may be participating in the regulation of the EhPgp5 gene expression.
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Affiliation(s)
- D G Pérez
- Department of Patología Experimental, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV Instituto Politecnico Nacional AP 14-740, México 07300, D.F. México
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Gómez C, Pérez DG, López-Bayghen E, Orozco E. Transcriptional analysis of the EhPgp1 promoter of Entamoeba histolytica multidrug-resistant mutant. J Biol Chem 1998; 273:7277-84. [PMID: 9516421 DOI: 10.1074/jbc.273.13.7277] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We present here the cloning and characterization of the EhPgp1 multidrug resistance gene promoter isolated from the Entamoeba histolytica drug-resistant mutant clone C2. The EhPgp1 promoter lacks the typical TATA box and the transcriptional initiation sequences described for other E. histolytica promoters. The major transcription initiation site of the EhPgp1 gene was located at the ATG start codon. The EhPgp1 core promoter located within the first 244 base pairs showed a higher chloramphenicol acetyltransferase expression in the transfected trophozoites of clone C2 than in those of the sensitive clone A. Gel shift assays revealed three specific DNA-protein complexes (Ia, IIa, and IIIc) using nuclear extracts from clone C2, whereas three main complexes (If, IIf, and IIg) were limited to clone A. Competition assays suggested the presence of C/EBP-like and OCT-like proteins in complexes Ia and IIa, respectively, probably involved in the expression of the EhPgp1 gene, whereas complex IIIc was competed by GATA-1, C/EBP, OCT, and HOX oligonucleotides. Thus, differential DNA-protein complexes may be formed by transcriptional factors involved in the regulation of the EhPgp1 gene expression.
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Affiliation(s)
- C Gómez
- Department of Patología Experimental, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV Instituto Politecnico Nacional, AP 14-740, Mexico 07300, Mexico
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Xu M, Molento M, Blackhall W, Ribeiro P, Beech R, Prichard R. Ivermectin resistance in nematodes may be caused by alteration of P-glycoprotein homolog. Mol Biochem Parasitol 1998; 91:327-35. [PMID: 9566525 DOI: 10.1016/s0166-6851(97)00215-6] [Citation(s) in RCA: 224] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Resistance to ivermectin and related drugs is an increasing problem for parasite control. The mechanism of ivermectin resistance in nematode parasites is currently unknown. Some P-glycoproteins and multidrug resistance proteins have been found to act as membrane transporters which pump drugs from the cell. A disruption of the mdrla gene, which encodes a P-glycoprotein in mice, results in hypersensitivity to ivermectin. Genes encoding members of the P-glycoprotein family are known to exist in nematodes but the involvement of P-glycoprotein in nematode ivermectin-resistance has not been described. Our data suggest that a P-glycoprotein may play a role in ivermectin resistance in the sheep nematode parasite Haemonchus contortus. A full length P-glycoprotein cDNA from H. contortus has been cloned and sequenced. Analysis of the sequence showed 61-65% homology to other P-glycoprotein/multidrug resistant protein sequences, such as mice, human and Caenorhabditis elegans. Expression of P-glycoprotein mRNA was higher in ivermectin-selected than unselected strains of H. contortus. An alteration in the restriction pattern was also found for the genomic locus of P-glycoprotein derived from ivermectin-selected strains of H. contortus compared with unselected strains. P-glycoprotein gene structure and/or its transcription are altered in ivermectin-selected H. contortus. The multidrug resistance reversing agent, verapamil, increased the efficacy of ivermectin and moxidectin against a moxidectin-selected strain of this nematode in jirds (Meriones unguiculatus). These data indicate that a P-glycoprotein may be involved in resistance to ivermectin and other macrocyclic lactones in H. contortus.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/chemistry
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/physiology
- Amino Acid Sequence
- Animals
- Anti-Bacterial Agents/pharmacology
- Antinematodal Agents/pharmacology
- Blotting, Northern
- Blotting, Southern
- Cloning, Molecular
- DNA, Complementary
- Drug Resistance, Multiple/genetics
- Female
- Genes, Helminth
- Gerbillinae
- Haemonchiasis/drug therapy
- Haemonchus/drug effects
- Haemonchus/genetics
- Haemonchus/growth & development
- Humans
- Ivermectin/pharmacology
- Macrolides
- Molecular Sequence Data
- Sequence Alignment
- Verapamil/pharmacology
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Affiliation(s)
- M Xu
- Institute of Parasitology, Macdonald Campus of McGill University, Ste-Anne-de-Bellevue, Quebec, Canada
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28
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Umbenhauer DR, Lankas GR, Pippert TR, Wise LD, Cartwright ME, Hall SJ, Beare CM. Identification of a P-glycoprotein-deficient subpopulation in the CF-1 mouse strain using a restriction fragment length polymorphism. Toxicol Appl Pharmacol 1997; 146:88-94. [PMID: 9299600 DOI: 10.1006/taap.1997.8225] [Citation(s) in RCA: 77] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
There is a subpopulation of the CF-1 mouse strain that is very sensitive to the neurotoxicity induced by the avermectins, a class of natural products widely used in veterinary and human medicine as anti-parasitic agents. This sensitivity results from a lack of P-glycoprotein in the intestine and brain of sensitive animals, allowing increased penetration of these compounds in the blood and brain, respectively. We describe a restriction fragment length polymorphism that is able to predict which animals will be deficient in this protein, confirming at the genetic level a heterogeneous population of this mouse strain. Breeding studies demonstrated that the inheritance of the markers follows a normal Mendelian autosomal pattern. Sensitive "-/-" animals are deficient in P-glycoprotein in those tissues known to express primarily mdr1a, but have normal P-glycoprotein levels in tissues known to express primarily mdr1b or mdr2, suggesting that the defect in the sensitive animals is limited to the mdr1a gene. The P-glycoprotein expression in the brain is dependent on the genotype, which also determines the susceptibility to the avermectin-induced neurotoxicity, with the "-/-" animals being most sensitive, and the "+/-" animals having less P-glycoprotein and therefore increased CNS sensitivity compared to the "+/+" animals. The ability to segregate this strain into -/- and +/+ animals may prove useful for examining the physiological role of P-glycoprotein in drug absorption and distribution and related toxicity. These data also provide a warning that experiments carried out with P-glycoprotein substrates in the heterogeneous population of the CF-1 mouse must be interpreted with caution.
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Affiliation(s)
- D R Umbenhauer
- Department of Safety Assessment, Merck Research Laboratories, West Point, Pennsylvania 19486, USA
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29
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Kim SH, Hur WY, Kang CD, Lim YS, Kim DW, Chung BS. Involvement of heat shock factor in regulating transcriptional activation of MDR1 gene in multidrug-resistant cells. Cancer Lett 1997; 115:9-14. [PMID: 9097973 DOI: 10.1016/s0304-3835(97)04725-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The present study provides evidence that heat shock factor (HSF) may be involved in a transacting factor modulating multidrug resistance 1 (MDR1) gene. In conjunction with the presence of several heat shock elements (HSEs) in the 5' region of the MDR1 gene, we compared the level of HSF which binds to HSEs in multidrug-resistant P388/M and FM3A/M cells with that in their parental counterparts. Under unstressed condition, these multidrug-resistant cells showed constitutive HSF DNA-binding activity in the nucleus of the cells, whereas their parental counterparts did not show detectable HSF DNA-binding activity. We found that H-87, protein kinase A inhibitor, inhibited HSF DNA-binding activity in heat-shocked P388/M cells and also suppressed the levels of hsp90 and hsp70. These results demonstrated that HSF might be an important transcriptional regulator for inducing MDR1 gene, and modulation of HSF activity might be a useful potential target for reversing MDR.
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Affiliation(s)
- S H Kim
- Department of Biochemistry, College of Medicine, Pusan National University, South Korea
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30
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Ernest S, Bello-Reuss E. Xenobiotic transport differences in mouse mesangial cell clones expressing mdr1 and mdr3. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 270:C910-9. [PMID: 8638674 DOI: 10.1152/ajpcell.1996.270.3.c910] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
P-glycoprotein (PGP), which confers multidrug resistance to cancer cells, is expressed in mouse kidney proximal tubule and mesangium. We report on the expression of PGP and its xenobiotic transport function in mesangial cells. Studies were performed in a mouse mesangial cell line (TKGM) and two cell clones. Ribonuclease protection assay and Western blot analysis demonstrated that TKGM cells expressed mdr1 and mdr3, the isoforms responsible for multidrug resistance. TKGM-F12 cells coexpressed mdr1 and mdr3 whereas TKGM-G2 cells expressed only mdr1. The drug transport function, measured by rhodamine 123 (R-123) efflux, was smaller in TKGM-F12 than in TKGM-G2 cells. The PGP substrates adriamycin, cyclosporin A, vinblastine, and verapamil inhibited R-123 transport in TKGM and TKGM-G2 cells. In the cells studied, PGP conferred some resistance to adriamycin; concomitant exposure to adriamycin with another PGP substrate impaired cell growth. The differential expression of mdr1 and mdr3 in mouse mesangial cell clones, the ability of mdr1 PGP to transport R-123, and the impairment of PGP-mediated transport in TKGM-F12 cells, coexpressing mdr1 and mdr3 products, are demonstrated. PGP may play a physiological role in mesangial cells.
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Affiliation(s)
- S Ernest
- Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555, USA
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31
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Borgnia MJ, Eytan GD, Assaraf YG. Competition of hydrophobic peptides, cytotoxic drugs, and chemosensitizers on a common P-glycoprotein pharmacophore as revealed by its ATPase activity. J Biol Chem 1996; 271:3163-71. [PMID: 8621716 DOI: 10.1074/jbc.271.6.3163] [Citation(s) in RCA: 135] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The aim of the present study was to demonstrate that the modulation of P-glycoprotein (Pgp) ATPase activity by peptides, drugs, and chemosensitizers takes place on a common drug pharmacophore. To this end, a highly emetine-resistant Chinese hamster ovary cell line was established, in which Pgp constituted 18% of plasma membrane protein. Reconstituted proteoliposomes, the Pgp content of which was up to 40%, displayed a basal activity of 2.6 +/- 0.45 micromol of Pi/min/mg of protein, suggesting the presence of an endogenous Pgp substrate. This basal ATPase activity was stimulated (up to 5.2 micromol of Pi/min/mg of protein) by valinomycin and various Pgp substrates, whereas, to our surprise, gramicidin D, an established Pgp substrate, was inhibitory. Taking advantage of this novel inhibition of Pgp ATPase activity by gramicidin D, a drug competition assay was devised in which gramicidin D-inhibited Pgp ATPase was coincubated with increasing concentrations of various substrates that stimulate its ATPase activity. Gramicidin D inhibition of Pgp ATPase was reversed by Pgp substrates, including various cytotoxic agents and chemosensitizers. The inhibition of the basal ATPase activity and the reversal of gramicidin D inhibition of Pgp ATPase by its various substrates conformed to classical Michaelis-Menten competition. This competition involved an endogenous substrate, the inhibitory drug gramicidin D, and a stimulatory substrate. We conclude that the various MDR type substrates and chemosensitizers compete on a common drug binding site present in Pgp.
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Affiliation(s)
- M J Borgnia
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
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32
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Affiliation(s)
- S P Cole
- Ontario Cancer Foundation, Kingston, Canada
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33
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Kane SE. Multidrug resistance of cancer cells. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0065-2490(96)80005-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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34
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Chapter 7 The P-glycoprotein family and multidrug resistance: An overview. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1383-8121(96)80048-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
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35
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Sonneveld P. Modulation of multidrug resistance in multiple myeloma. BAILLIERE'S CLINICAL HAEMATOLOGY 1995; 8:831-44. [PMID: 8845575 DOI: 10.1016/s0950-3536(05)80262-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Primary or acquired drug resistance is the major cause of failure of chemotherapy in MM. MDR is associated with expression of a membrane P-gp, which acts as an efflux pump for natural product drugs, such as doxorubicin and vincristine. P-gp expression is observed in extensively treated patients and is a cause of refractoriness to VAD chemotherapy. Among several other non-cytotoxic drugs, cyclosporins modulate the function of P-gp in refractory myeloma cells. Early clinical trials with verapamil and cyclosporin have shown that these can be combined with VAD. In patients treated with drug-resistance modifiers, there is, besides an effect on the tumour cell, also an increased plasma exposure to several cytostatic drugs, which is mediated through inhibition of biliary efflux. Thus, the clinical effect of drug modulation may result from inhibition of tumour P-gp and from altered drug pharmacokinetics. Several trials are now in progress in order to evaluate the clinical benefit of resistance modulators in myeloma.
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Affiliation(s)
- P Sonneveld
- Department of Haematology, University Hospital Rotterdam Dykzig, Netherlands
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36
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Ruetz S, Gros P. Enhancement of Mdr2-mediated phosphatidylcholine translocation by the bile salt taurocholate. Implications for hepatic bile formation. J Biol Chem 1995; 270:25388-95. [PMID: 7592705 DOI: 10.1074/jbc.270.43.25388] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Expression of the Mdr2-protein in secretory vesicules (SVs) from the yeast mutant sec6-4 causes a time- and temperature-dependent enhancement of phosphatidylcholine (PC) translocation from the outer to the inner leaflet of the SV lipid bilayer. We show that this activity is independent of changes either in the membrane potential or the pH gradient (inside positive) generated in these SVs by the yeast proton-translocating PMA1 ATPase. However, loading of the SVs with the primary bile salt taurocholate results in an apparent enhancement of Mdr2-mediated PC translocation activity. Reducing the intravesicular taurocholate (TC) concentration by dissipating the electrochemical potential across the SV membranes eliminates the enhancing effect of TC. Three lines of evidence suggest that the enhanced Mdr2-mediated PC translocation activity is not caused by a regulatory effect of TC on Mdr2 but rather reflected the formation of TC/PC aggregates or micelles in the lumen of SVs. First, significantly higher detergent concentrations are required to reveal the fluorescence of (7-nitro-2-1,3-benzoxadiazol-4-yl)amino-PC molecules translocated in Mdr2-SV under conditions of TC stimulation than under control conditions; second, the nonmicelle-forming bile salt taurodehydrocholate does not cause enhancement of PC translocation in Mdr2-SVs; third, enzyme marker studies indicate that TC behaves as a potent lipid solubilizer directly extracting PC molecules out of the bilayer without causing leakage. This results in the formation of intravesicular aggregates or mixed micelles, and provokes the apparent stimulation of Mdr2 activity. These data demonstrate a unique relationship between Mdr2, PC, and TC in the process of bile formation and secretion.
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Affiliation(s)
- S Ruetz
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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37
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Castillo G, Shen HJ, Horwitz SB. A homologue of the mammalian multidrug resistance gene (mdr) is functionally expressed in the intestine of Xenopus laevis. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1262:113-23. [PMID: 7599185 DOI: 10.1016/0167-4781(95)00056-m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
P-glycoprotein is an integral membrane protein that functions in multidrug resistance (MDR) cells as a drug efflux pump to maintain intracellular concentrations of antitumor drugs below cytotoxic levels. A homologue of the mammalian mdr gene has been isolated and characterized from Xenopus laevis (Xe-mdr). The cDNA was isolated from a tadpole cDNA library using the full length mouse mdrlb cDNA as a probe. The Xe-mdr encodes a protein that is 66% identical to the mouse mdrlb and 68% identical to the human mdrl. The predicted structure of the Xe-mdr gene product identifies twelve membrane spanning domains and two ATP binding sites both of which are the hallmark of the ABC (ATP binding cassette) transporters. Xe-mdr mRNA is expressed as a single message of 4.5 kb and is found predominantly in the intestine. Xe-mdr message is increased 3- to 4-fold in the ileum compared to the rest of the small intestine. In situ hybridization of sequential sections from the small intestine localized the expression of the Xe-mdr to the cells lining the lumenal epithelium. Brush border membrane vesicles prepared from the small intestine of Xenopus laevis effluxed vinblastine in an ATP-dependent manner. Efflux was decreased by verapamil, a known inhibitor of P-glycoprotein function. These studies indicate that the structure of Xe-mdr has been conserved and suggest that the protein has a role in maintaining the function of the normal intestine in Xenopus.
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Affiliation(s)
- G Castillo
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
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38
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Silverman JA, Hill BA. Characterization of the basal and carcinogen regulatory elements of the rat mdr1b promoter. Mol Carcinog 1995; 13:50-9. [PMID: 7766310 DOI: 10.1002/mc.2940130109] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In this report we characterized the transcriptional regulation of the rat mdr1b gene by xenobiotics. The expression of this gene was increased in primary rat hepatocytes and in the H4-II-E hepatoma cell line by exposure to carcinogens such as aflatoxin B1, N-acetoxy-2-acetylaminofluorene, and methyl methanesulfonate. Nuclear run-on experiments indicated that the higher steady-state levels of mdr1b mRNA were due to an increase in transcription. The 5'-flanking region of the mdr1b gene was isolated, sequenced, and functionally characterized in transient and stable transfection assays. A single transcription start site was identified for this gene; no alternate start sites were used after induction with aflatoxin B1. Deletion analysis of this promoter demonstrated that the sequence between nt -214 and -178 was critical for basal promoter activity. This region did not contain any consensus-binding sites for previously identified transcription factors. A negative regulatory region was also identified between nt -940 and -250. No specific carcinogen-responsive element was identified; the xenobiotic response required a large part of the promoter. These data suggest that the carcinogen induction of mdr1b expression is mediated through sequences that overlap or that are identical to the basal promoter element.
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Affiliation(s)
- J A Silverman
- Laboratory of Experimental Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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39
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Ince TA, Scotto KW. Differential utilization of multiple transcription start points accompanies the overexpression of the P-glycoprotein-encoding gene in Chinese hamster lung cells. Gene X 1995; 156:287-90. [PMID: 7758970 DOI: 10.1016/0378-1119(94)00907-a] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The overproduction of P-glycoprotein (Pgp) has been associated with the development and maintenance of the multidrug resistant (MDR) phenotype, although the regulatory events responsible have not yet been elucidated. We have analyzed the overexpression of the TATA-less hamster class-I Pgp-encoding gene (Pgp1) in several MDR Chinese hamster cell lines. The MDR lung cell line DC-3F/VCRd5L, as well as the MDR ovary cell line CHRC5, express a level of Pgp1 RNA commensurate with the increase in Pgp1 dosage; in contrast, the actinomycin D (ActD)-selected sublines of DC-3F overexpress Pgp1 mRNA without a concomitant increase in Pgp1 gene-copy number. Analysis of Pgp1 transcription start point (tsp) utilization revealed that drug-sensitive DC-3F cells, as well as DC-3F/VCRd5L and CHRC5 cells, utilize one major tsp; in contrast, the ActD-resistant sublines 'switch' to a more complex pattern, using four additional Pgp1 tsp 32, 42, 52, and 67 bp downstream from the major parental tsp (+1). This observation of a difference in the regulation of transcription of Pgp in MDR vs. drug-sensitive cells suggests that the 'switch' in tsp selection may be involved in the increased expression of Pgp1 mRNA. Interestingly, despite the existence of several hundred MDR cell lines, very few have been analyzed with respect to tsp selection; it is therefore possible that alternate tsp selection is a relatively common yet heretofore unobserved component of the MDR phenotype. Moreover, these cells provide an excellent system in which to evaluate the sequence elements and protein factors that govern the selection of tsp in TATA-less promoters.
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Affiliation(s)
- T A Ince
- Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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40
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Shustik C, Dalton W, Gros P. P-glycoprotein-mediated multidrug resistance in tumor cells: biochemistry, clinical relevance and modulation. Mol Aspects Med 1995; 16:1-78. [PMID: 7783568 DOI: 10.1016/0098-2997(94)00040-a] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- C Shustik
- Department of Medicine, McGill Cancer Center, Royal Victoria Hospital, Montreal, Quebec, Canada
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41
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Kirschner LS. Amplification of the murine mdr2 gene and a reconsideration of the structure of the murine mdr gene locus. DNA Cell Biol 1995; 14:47-59. [PMID: 7832992 DOI: 10.1089/dna.1995.14.47] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
A common feature of cells selected in vitro for the multidrug resistance (MDR) phenotype is the amplification and concomitant overexpression of the mdr genes. In murine macrophage-like J774.2-derived MDR cell lines, there is a good correlation between levels of amplification and expression for the mdr1b gene, but not for the other two gene family members, mdr1a and mdr2. To understand this phenomenon better, a study of the amplification and expression of the mdr2 gene was undertaken. Southern blotting of genomic DNAs from a series of six MDR cell lines revealed that five of these lines had 5'-end amplification of mdr2, whereas only three contained 3'-end amplification. The analysis also suggested the involvement of a recombination hot-spot in this phenomenon. Despite the observation that the ratio between the number of copies of the 5' and 3' ends of the gene differs among cell lines, the ratio of 5' to 3' end transcription of mdr2 was approximately 1 in all cell lines. An analysis of promoter methylation in MDR cell lines demonstrated that this mechanism may play a role in regulating the transcription of mdr2, but not of mdr1b. Long-range mapping of the mdr locus in parental and amplified cell lines suggested that the three mdr genes are oriented in the same direction, and also revealed the presence of a number of rearrangement events. Models for the murine mdr gene locus in wild-type cells and in a cell line containing a rearrangement are presented.
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Affiliation(s)
- L S Kirschner
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461
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42
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Baba M, Nakanishi O, Sato W, Saito A, Miyama Y, Yano O, Shimada S, Fukazawa N, Naito M, Tsuruo T. Relationship between multidrug resistant gene expression and multidrug resistant-reversing effect of MS-209 in various tumor cells. Cancer Chemother Pharmacol 1995; 36:361-7. [PMID: 7634376 DOI: 10.1007/bf00686183] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
MS-209 is a novel quinoline compound which can overcome multidrug resistance (MDR) both in vitro and in vivo, while having a low level of side effects, and is now being evaluated in a clinical phase II study. Reverse transcription-polymerase chain reaction (RT-PCR) was used to quantitate the expression levels of MDR genes in various mouse and human tumor cell lines. The MDR gene and the beta actin gene, as the internal reference standard, were coamplified separately, and the relative expression of the MDR gene was represented by the MDR/beta actin ratio. The in vitro MDR-reversing effect of MS-209 was then compared with the MDR gene expression (MDR/beta actin ratio). We found a significant correlation between these two parameters. Moreover, a significant correlation was also observed between the level of expression of the MDR1 gene and that of P-glycoprotein in human cell lines. Therefore, the efficacy of MS-209 seems to specifically depend on the level of MDR gene expression (P-glycoprotein). From these observations, it is suggested that RT-PCR assays of MDR1 gene in tumor biopsy specimens might be an effective means to predict the response of tumor cells to combination therapy with MS-209.
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Affiliation(s)
- M Baba
- Institute of Biological Science, Mitsui Pharmaceuticals, Inc., Chiba, Japan
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43
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Schlemmer SR, Sirotnak FM. Functional studies of P-glycoprotein in inside-out plasma membrane vesicles derived from murine erythroleukemia cells overexpressing MDR 3. Properties and kinetics of the interaction of vinblastine with P-glycoprotein and evidence for its active mediated transport. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)47390-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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44
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Balzi E, Goffeau A. Genetics and biochemistry of yeast multidrug resistance. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1187:152-62. [PMID: 8075109 DOI: 10.1016/0005-2728(94)90102-3] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- E Balzi
- Unité de Biochimie Physiologique, Université Catholique de Louvain, Belgium
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45
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Gekeler V, Beck J, Noller A, Wilisch A, Frese G, Neumann M, Handgretinger R, Ehninger G, Probst H, Niethammer D. Drug-induced changes in the expression of MDR-associated genes: investigations on cultured cell lines and chemotherapeutically treated leukemias. Ann Hematol 1994; 69 Suppl 1:S19-24. [PMID: 7914748 DOI: 10.1007/bf01757350] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The induced expression of multiple drug resistance (MDR)-associated genes as a direct response of tumor cells to antineoplastic drugs could be an important factor influencing the success of cancer chemotherapy. We investigated the effects of such compounds on mdr1/P-glycoprotein (P-gp) gene expression and drug sensitivities in the T-lymphoblastoid human cell line CCRF-CEM and MDR sublines. Thereby, we observed that actinomycin D or adriamycin administered at sublethal concentrations induced increases of mdr1 mRNA levels and resistance within 72 h. Furthermore, on leukemia cell samples collected before and after chemotherapy we checked by a complementary DNA polymerase chain reaction (cDNA-PCR) approach for similar alterations in the relative expression levels of the MDR-associated genes (a) mdr1/P-gp (b) mrp (MDR related protein), and (c) the topoisomerase II isoforms alpha and beta. We found a concomitant increase in mdr1 and mrp gene expression combined with a decreased expression of topoisomerase II alpha in the course of the second relapse of an acute lymphoblastic leukemia (ALL). This points to the emergence of at least three different MDR mechanisms in this type of leukemia unresponsive to chemotherapy. A chronic myeloid leukemia (CML) in blast crisis, however, showed combined increases in mdr1 (about 20-fold) and mrp (about four fold) gene expression after intense but unsuccessful chemotherapy over a 6-month period. Our results indicate the occurrence of induced resistance in vitro and in vivo and suggest a contribution of the newly identified ATP-binding cassette (ABC) transporter MRP in MDR.
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Affiliation(s)
- V Gekeler
- Abteilung FP3, Byk Gulden GmbH, Konstanz, Germany
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46
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Cohen D, Yu L, Rzepka R, Horwitz SB. Identification of two nuclear protein binding sites and their role in the regulation of the murine multidrug resistance mdr1a promoter. DNA Cell Biol 1994; 13:641-9. [PMID: 7912938 DOI: 10.1089/dna.1994.13.641] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Multidrug resistance genes (mdr) that encode P-glycoproteins (P-gp) are transcriptionally regulated in normal tissues and in some multidrug-resistant (MDR) cells. Several lines of evidence suggest that regulation of P-gp overexpression at the transcriptional level is also important in human tumors. In murine MDR cells, mdr1a and/or mdr1b genes are overexpressed and P-gp isoforms are overproduced. To identify the mdr1a promoter regions that are required for transcription, the promoter has been linked to the chloramphenicol acetyltransferase (CAT) gene in transient expression vectors. 5'-Deletions of the promoter sequences have demonstrated that the region between -155 to +89 bp is crucial for basal activity of the mdr1a gene. DNase I footprinting, methylation interference, and gel retardation assays identified two nuclear protein binding sites within these sequences. One of the nuclear protein binding sites contains an 11-bp DNA sequence that interacts with nuclear protein(s) and is conserved in the promoters of the murine mdr1a and mdr1b, hamster pgp1, and human MDR1 genes. The conserved SP1 site (5'-GGGCGGG-3') that is present further downstream was shown to interact with its nuclear factor. These observations suggest that at least part of mdr gene transcriptional regulation is mediated by conserved mdr cis-regulatory elements and common nuclear factors.
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Affiliation(s)
- D Cohen
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY 10461
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Kajiji S, Dreslin JA, Grizzuti K, Gros P. Structurally distinct MDR modulators show specific patterns of reversal against P-glycoproteins bearing unique mutations at serine939/941. Biochemistry 1994; 33:5041-8. [PMID: 8172879 DOI: 10.1021/bi00183a006] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The mechanism by which P-glycoprotein (P-gp) interacts with a number of structurally unrelated substrates or inhibitors remains unknown. We have recently shown that a serine residue within the predicted transmembrane (TM) domain 11 of P-gps encoded by mouse mdr1 (Ser941) and mdr3 (Ser939) plays an important role in the substrate specificity of P-gp. We wished to determine if Ser939/941 is also important for efficient interaction of P-gp with structurally different modulating agents, a cyclic peptide (cyclosporin A, CsA), a diaminoquinazoline (CP100356), and a chiral, tricyclic structure (CP117227). For this, the capacity of these compounds to modulate the vinblastine (VBL) resistance phenotype of transfected cells expressing similar levels of P-gps bearing either the wild-type Ser or a mutant Phe at position 941 (mdr1) or 939 (mdr3) was initially tested. The Ser-->Phe substitution indeed affected the potency and P-gp isoform specificity of some of the modulators, in particular that of CP117227 (racemic mixture and enantiomers), which were active against wild-type but not mutant mdr3. The modulatory effect of the mutation on CP117227-mediated reversal of VBL resistance was parallelled by a comparable modulation of the steady-state levels of VBL accumulation in Ser939- and Phe939-expressing cells, but was not linked to differential cellular accumulation of the modulator, which was identical in both cell types. To further assess the role of this amino acid residue in P-gp interactions with modulators, the effect of additional mutations (Ala, Cys, Thr, Asp, Tyr, Trp) at that site on potencies of CsA, CP117227 enantiomers, and CP100356 was evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Kajiji
- Department of Cancer, Pfizer Central Research, Groton, Connecticut 06340
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Loo T, Clarke D. Functional consequences of glycine mutations in the predicted cytoplasmic loops of P-glycoprotein. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37274-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Savaraj N, Lampidis TJ, Zhao JY, Wu CJ, Teeter LD, Kuo MT. Two multidrug-resistant Friend leukemic cell lines selected with different drugs exhibit overproduction of different P-glycoproteins. Cancer Invest 1994; 12:138-44. [PMID: 7907527 DOI: 10.3109/07357909409024869] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Two Friend leukemic multidrug-resistance (MDR) cell lines were established by exposure to stepwise increased concentrations of rhodamine-123 (RHO) (cell line RR-30) or Adriamycin (ADR) (cell line ARN-15). RR-30 displays preferential resistance to RHO, whereas ARN-15 is more resistant to ADR. The levels of resistance to other MDR drugs and reversibility by verapamil between these two MDR cell lines were somewhat different. Southern blot, RNase protection, and Western blot analysis using gene-specific probes demonstrated that RR-30 and ARN-15 cells preferentially amplified the mdr1 and mdr3 genes, respectively, leading to overexpression of the corresponding P-glycoproteins (p-gp). Our results suggest that members of the mdr gene family can be amplified independently by using different selecting agents, which could be responsible for the differences in the sensitivities to these selecting agents as well as to these MDR drugs.
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Affiliation(s)
- N Savaraj
- Department of Oncology, University of Miami, Florida 33101
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Affiliation(s)
- E Buschman
- Department of Biochemistry, McGill University, Montreal, Quebec, Canada
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