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Sample records for multirresistencia drogas mdr1

  1. In Vivo Imaging of Human MDR1 Transcription in the Brain and Spine of MDR1-Luciferase Reporter Mice

    PubMed Central

    Yasuda, Kazuto; Cline, Cynthia; Lin, Yvonne S.; Scheib, Rachel; Ganguly, Samit; Thirumaran, Ranjit K.; Chaudhry, Amarjit; Kim, Richard B.

    2015-01-01

    P-glycoprotein (Pgp) [the product of the MDR1 (ABCB1) gene] at the blood-brain barrier (BBB) limits central nervous system (CNS) entry of many prescribed drugs, contributing to the poor success rate of CNS drug candidates. Modulating Pgp expression could improve drug delivery into the brain; however, assays to predict regulation of human BBB Pgp are lacking. We developed a transgenic mouse model to monitor human MDR1 transcription in the brain and spinal cord in vivo. A reporter construct consisting of ∼10 kb of the human MDR1 promoter controlling the firefly luciferase gene was used to generate a transgenic mouse line (MDR1-luc). Fluorescence in situ hybridization localized the MDR1-luciferase transgene on chromosome 3. Reporter gene expression was monitored with an in vivo imaging system following D-luciferin injection. Basal expression was detectable in the brain, and treatment with activators of the constitutive androstane, pregnane X, and glucocorticoid receptors induced brain and spinal MDR1-luc transcription. Since D-luciferin is a substrate of ABCG2, the feasibility of improving D-luciferin brain accumulation (and luciferase signal) was tested by coadministering the dual ABCB1/ABCG2 inhibitor elacridar. The brain and spine MDR1-luc signal intensity was increased by elacridar treatment, suggesting enhanced D-luciferin brain bioavailability. There was regional heterogeneity in MDR1 transcription (cortex > cerebellum) that coincided with higher mouse Pgp protein expression. We confirmed luciferase expression in brain vessel endothelial cells by ex vivo analysis of tissue luciferase protein expression. We conclude that the MDR1-luc mouse provides a unique in vivo system to visualize MDR1 CNS expression and regulation. PMID:26281846

  2. In Vivo Imaging of Human MDR1 Transcription in the Brain and Spine of MDR1-Luciferase Reporter Mice.

    PubMed

    Yasuda, Kazuto; Cline, Cynthia; Lin, Yvonne S; Scheib, Rachel; Ganguly, Samit; Thirumaran, Ranjit K; Chaudhry, Amarjit; Kim, Richard B; Schuetz, Erin G

    2015-11-01

    P-glycoprotein (Pgp) [the product of the MDR1 (ABCB1) gene] at the blood-brain barrier (BBB) limits central nervous system (CNS) entry of many prescribed drugs, contributing to the poor success rate of CNS drug candidates. Modulating Pgp expression could improve drug delivery into the brain; however, assays to predict regulation of human BBB Pgp are lacking. We developed a transgenic mouse model to monitor human MDR1 transcription in the brain and spinal cord in vivo. A reporter construct consisting of ∼10 kb of the human MDR1 promoter controlling the firefly luciferase gene was used to generate a transgenic mouse line (MDR1-luc). Fluorescence in situ hybridization localized the MDR1-luciferase transgene on chromosome 3. Reporter gene expression was monitored with an in vivo imaging system following D-luciferin injection. Basal expression was detectable in the brain, and treatment with activators of the constitutive androstane, pregnane X, and glucocorticoid receptors induced brain and spinal MDR1-luc transcription. Since D-luciferin is a substrate of ABCG2, the feasibility of improving D-luciferin brain accumulation (and luciferase signal) was tested by coadministering the dual ABCB1/ABCG2 inhibitor elacridar. The brain and spine MDR1-luc signal intensity was increased by elacridar treatment, suggesting enhanced D-luciferin brain bioavailability. There was regional heterogeneity in MDR1 transcription (cortex > cerebellum) that coincided with higher mouse Pgp protein expression. We confirmed luciferase expression in brain vessel endothelial cells by ex vivo analysis of tissue luciferase protein expression. We conclude that the MDR1-luc mouse provides a unique in vivo system to visualize MDR1 CNS expression and regulation.

  3. Caveolin-1 expression in ovarian carcinoma is MDR1 independent.

    PubMed

    Davidson, Ben; Goldberg, Iris; Givant-Horwitz, Vered; Nesland, Jahn M; Berner, Aasmund; Bryne, Magne; Risberg, Bjørn; Kopolovic, Juri; Kristensen, Gunnar B; Tropé, Claes G; van de Putte, Gregg; Reich, Reuven

    2002-02-01

    We studied the role of caveolin-1 in tumor progression and prognosis in serous ovarian carcinoma and the association between caveolin-1 and MDR1 expression. The study involved immunohistochemical analysis for caveolin-1 and P-glycoprotein (P-gp) expression in 75 effusions and 90 solid lesions from ovarian and primary peritoneal carcinoma; in situ hybridization for MDR1 messenger RNA (mRNA) expression in 62 effusions and all 90 tumors; and reverse transcription-polymerase chain reaction (RT-PCR) for caveolin-1 mRNA expression in 23 effusions. Immunohistochemical analysis localized caveolin-1 to the cell membrane in 43 effusions and 24 tumors. P-gp membrane expression was detected in 14 effusions and 11 tumors; MDR1 mRNA, in 20 effusions and 30 tumors. Caveolin-1 mRNA was expressed in 19 effusions. Caveolin-1 protein expression showed no association with that of P-gp protein or MDR1 mRNA. The expression of all markers was similar in carcinoma cells in pleural and peritoneal effusions. Caveolin-1 is a novel diagnostic marker for effusions; expression is moderately elevated in tumor cells in effusions, possibly owing to altered signal transduction and metabolism in cancer cells at this site. Expression seems MDR1 independent. PMID:11863219

  4. Treatment of MDR1 Mutant Dogs with Macrocyclic Lactones

    PubMed Central

    Geyer, Joachim; Janko, Christina

    2012-01-01

    P-glycoprotein, encoded by the multidrug resistance gene MDR1, is an ATP-driven drug efflux pump which is highly expressed at the blood-brain barrier of vertebrates. Drug efflux of macrocyclic lactones by P-glycoprotein is highly relevant for the therapeutic safety of macrocyclic lactones, as thereby GABA-gated chloride channels, which are confined to the central nervous system in vertebrates, are protected from high drug concentrations that otherwise would induce neurological toxicity. A 4-bp deletion mutation exists in the MDR1 gene of many dog breeds such as the Collie and the Australian Shepherd, which results in the expression of a non-functional P-glycoprotein and is associated with multiple drug sensitivity. Accordingly, dogs with homozygous MDR1 mutation are in general prone to neurotoxicity by macrocyclic lactones due to their increased brain penetration. Nevertheless, treatment of these dogs with macrocyclic lactones does not inevitably result in neurological symptoms, since, the safety of treatment highly depends on the treatment indication, dosage, route of application, and the individual compound used as outlined in this review. Whereas all available macrocyclic lactones can safely be administered to MDR1 mutant dogs at doses usually used for heartworm prevention, these dogs will experience neurological toxicity following a high dose regimen which is common for mange treatment in dogs. Here, we review and discuss the neurotoxicological potential of different macrocyclic lactones as well as their treatment options in MDR1 mutant dogs. PMID:22039792

  5. Etoposide enhances antitumor efficacy of MDR1-driven oncolytic adenovirus through autoupregulation of the MDR1 promoter activity

    PubMed Central

    Tseng, Yau-Lin; Shiau, Ai-Li; Wu, Chao-Liang

    2015-01-01

    Conditionally replicating adenoviruses (CRAds), or oncolytic adenoviruses, such as E1B55K-deleted adenovirus, are attractive anticancer agents. However, the therapeutic efficacy of E1B55K-deleted adenovirus for refractory solid tumors has been limited. Environmental stress conditions may induce nuclear accumulation of YB-1, which occurs in multidrug-resistant and adenovirus-infected cancer cells. Overexpression and nuclear localization of YB-1 are associated with poor prognosis and tumor recurrence in various cancers. Nuclear YB-1 transactivates the multidrug resistance 1 (MDR1) genes through the Y-box. Here, we developed a novel E1B55K-deleted adenovirus driven by the MDR1 promoter, designed Ad5GS3. We tested the feasibility of using YB-1 to transcriptionally regulate Ad5GS3 replication in cancer cells and thereby to enhance antitumor efficacy. We evaluated synergistic antitumor effects of oncolytic virotherapy in combination with chemotherapy. Our results show that adenovirus E1A induced E2F-1 activity to augment YB-1 expression, which shut down host protein synthesis in cancer cells during adenovirus replication. In cancer cells infected with Ad5WS1, an E1B55K-deleted adenovirus driven by the E1 promoter, E1A enhanced YB-1 expression, and then further phosphorylated Akt, which, in turn, triggered nuclear translocation of YB-1. Ad5GS3 in combination with chemotherapeutic agents facilitated nuclear localization of YB-1 and, in turn, upregulated the MDR1 promoter activity and enhanced Ad5GS3 replication in cancer cells. Thus, E1A, YB-1, and the MDR1 promoter form a positive feedback loop to promote Ad5GS3 replication in cancer cells, and this regulation can be further augmented when chemotherapeutic agents are added. In the in vivo study, Ad5GS3 in combination with etoposide synergistically suppressed tumor growth and prolonged survival in NOD/SCID mice bearing human lung tumor xenografts. More importantly, Ad5GS3 exerted potent oncolytic activity against clinical

  6. Trps1 is associated with the multidrug resistance of osteosarcoma by regulating MDR1 gene expression.

    PubMed

    Jia, Ming; Hu, Jing; Li, Weiwei; Su, Peng; Zhang, Hui; Zhang, Xiaofang; Zhou, Gengyin

    2014-03-01

    Multidrug resistance (MDR) is a significant clinical problem in the chemotherapy of osteosarcoma and has been linked to the cellular expression of several multidrug-efflux transporters such as MDR1/P-gp. Our inhibition of the transcription factor Trps1 led to repression of MDR1/P-gp while its overexpression resulted in upregulation of MDR1/P-gp. Flow cytometric analysis suggested Trps1 increased the release of several anti-cancer drugs, thus decreasing their accumulation. Immunohistochemical analysis of clinical samples indicated that the expression of Trps1 directly correlated with MDR1/P-gp. Trps1 inhibited TGFbeta-1 and directly bound to the MDR1 promoter. Our data demonstrate a role for Trps1 in the regulation of MDR1 expression in osteosarcoma. PMID:24491996

  7. MDR1 Transporter Protects Against Paraquat-Induced Toxicity in Human and Mouse Proximal Tubule Cells

    PubMed Central

    Wen, Xia; Gibson, Christopher J.; Yang, Ill; Buckley, Brian; Goedken, Michael J.; Richardson, Jason R.; Aleksunes, Lauren M.

    2014-01-01

    Paraquat is a herbicide that is highly toxic to the lungs and kidneys following acute exposures. Prior studies have demonstrated that the organic cation transporter 2 and multidrug and toxin extrusion protein 1 contribute to the urinary secretion of paraquat in the kidneys. The purpose of this study was to determine whether the multidrug resistance protein 1 (MDR1/Mdr1, ABCB1, or P-glycoprotein) also participates in the removal of paraquat from the kidneys and protects against renal injury. Paraquat transport and toxicity were quantified in human renal proximal tubule epithelial cells (RPTEC) that endogenously express MDR1, HEK293 cells overexpressing MDR1, and Mdr1a/1b knockout mice. In RPTEC cells, reduction of MDR1 activity using the antagonist PSC833 or siRNA transfection increased the cellular accumulation of paraquat by 50%. Reduced efflux of paraquat corresponded with enhanced cytotoxicity in PSC833-treated cells. Likewise, stable overexpression of the human MDR1 gene in HEK293 cells reduced intracellular levels of paraquat by 50%. In vivo studies assessed the renal accumulation and subsequent nephrotoxicity of paraquat (10 or 30 mg/kg ip) in wild-type and Mdr1a/1b knockout mice. At 4 h after paraquat treatment, renal concentrations of paraquat in the kidneys of Mdr1a/1b knockout mice were 750% higher than wild-type mice. By 72 h, paraquat-treated Mdr1a/1b knockout mice had more extensive tubular degeneration and significantly greater mRNA expression of kidney injury-responsive genes, including kidney injury molecule-1, lipocalin-2, and NAD(P)H quinone oxidoreductase 1, compared with wild-type mice. In conclusion, MDR1/Mdr1 participates in the elimination of paraquat from the kidneys and protects against subsequent toxicity. PMID:25015657

  8. Detection of MDR1 mRNA expression with optimized gold nanoparticle beacon

    NASA Astrophysics Data System (ADS)

    Zhou, Qiumei; Qian, Zhiyu; Gu, Yueqing

    2016-03-01

    MDR1 (multidrug resistance gene) mRNA expression is a promising biomarker for the prediction of doxorubicin resistance in clinic. However, the traditional technical process in clinic is complicated and cannot perform the real-time detection mRNA in living single cells. In this study, the expression of MDR1 mRNA was analyzed based on optimized gold nanoparticle beacon in tumor cells. Firstly, gold nanoparticle (AuNP) was modified by thiol-PEG, and the MDR1 beacon sequence was screened and optimized using a BLAST bioinformatics strategy. Then, optimized MDR1 molecular beacons were characterized by transmission electron microscope, UV-vis and fluorescence spectroscopies. The cytotoxicity of MDR1 molecular beacon on L-02, K562 and K562/Adr cells were investigated by MTT assay, suggesting that MDR1 molecular beacon was low inherent cytotoxicity. Dark field microscope was used to investigate the cellular uptake of hDAuNP beacon assisted with ultrasound. Finally, laser scanning confocal microscope images showed that there was a significant difference in MDR1 mRNA expression in K562 and K562/Adr cells, which was consistent with the results of q-PCR measurement. In summary, optimized MDR1 molecular beacon designed in this study is a reliable strategy for detection MDR1 mRNA expression in living tumor cells, and will be a promising strategy for in guiding patient treatment and management in individualized medication.

  9. Effect of MDR1 gene polymorphisms on mortality in paraquat intoxicated patients.

    PubMed

    Kim, Hak Jae; Kim, Hyung-Ki; Kwon, Jun-Tack; Lee, Sun-Hyo; El Park, Sam; Gil, Hyo-Wook; Song, Ho-Yeon; Hong, Sae-Yong

    2016-01-01

    Paraquat is a fatal herbicide following acute exposure. Previous studies have suggested that multidrug resistance protein 1 (MDR1) might help remove paraquat from the lungs and the kidney. MDR1 single-nucleotide polymorphisms (SNPs) are involved in the pharmacokinetics of many drugs. The purpose of this study was to determine whether MDR1 SNPs were associated with the mortality in paraquat intoxicated patients. We recruited 109 patients admitted with acute paraquat poisoning. They were genotyped for C1236T, G2677T/A, and C3435T single-nucleotide polymorphisms (SNPs) of MDR1 gene. Their effects on mortality of paraquat intoxicated patients were evaluated. Overall mortality rate was 66.1%. Regarding the C1236T of the MDR1 gene polymorphism, 21 (19.3%) had the wild type MDR1 while 88 (80.7%) had homozygous mutation. Regarding the C3435T MDR1 gene polymorphism, 37(33.9%) patients had the wild type, 23 (21.1%) had heterozygous mutation, and 49 (45.0%) had homozygous mutation. Regarding the G2677T/A MDR1 gene polymorphism, 38 (34.9%) patients had the wild type, 57 (52.3%) had heterozygous mutation, and 14 (12.8%) had homozygous mutation. None of the individual mutations or combination of mutations (two or three) of MDR1 SNP genotypes altered the morality rate. The mortality rate was not significantly different among SNP groups of patients with <4.0 μg/mL paraquat. In conclusion, MDR1 SNPs have no effect on the mortality rate of paraquat intoxicated patients. PMID:27545861

  10. Effect of MDR1 gene polymorphisms on mortality in paraquat intoxicated patients

    PubMed Central

    Kim, Hak Jae; Kim, Hyung-Ki; Kwon, Jun-Tack; Lee, Sun-hyo; el Park, Sam; Gil, Hyo-Wook; Song, Ho-yeon; Hong, Sae-yong

    2016-01-01

    Paraquat is a fatal herbicide following acute exposure. Previous studies have suggested that multidrug resistance protein 1 (MDR1) might help remove paraquat from the lungs and the kidney. MDR1 single-nucleotide polymorphisms (SNPs) are involved in the pharmacokinetics of many drugs. The purpose of this study was to determine whether MDR1 SNPs were associated with the mortality in paraquat intoxicated patients. We recruited 109 patients admitted with acute paraquat poisoning. They were genotyped for C1236T, G2677T/A, and C3435T single-nucleotide polymorphisms (SNPs) of MDR1 gene. Their effects on mortality of paraquat intoxicated patients were evaluated. Overall mortality rate was 66.1%. Regarding the C1236T of the MDR1 gene polymorphism, 21 (19.3%) had the wild type MDR1 while 88 (80.7%) had homozygous mutation. Regarding the C3435T MDR1 gene polymorphism, 37(33.9%) patients had the wild type, 23 (21.1%) had heterozygous mutation, and 49 (45.0%) had homozygous mutation. Regarding the G2677T/A MDR1 gene polymorphism, 38 (34.9%) patients had the wild type, 57 (52.3%) had heterozygous mutation, and 14 (12.8%) had homozygous mutation. None of the individual mutations or combination of mutations (two or three) of MDR1 SNP genotypes altered the morality rate. The mortality rate was not significantly different among SNP groups of patients with <4.0 μg/mL paraquat. In conclusion, MDR1 SNPs have no effect on the mortality rate of paraquat intoxicated patients. PMID:27545861

  11. Tryptanthrin inhibits MDR1 and reverses doxorubicin resistance in breast cancer cells

    SciTech Connect

    Yu, S.-T.; Chen, T.-M.; Tseng, S.-Y.; Chen, Y.-H. . E-mail: tcyhchen@ntu.edu.tw

    2007-06-22

    Development of agents to overcome multidrug resistance (MDR) is important in cancer chemotherapy. Up to date, few chemicals have been reported to down-regulate MDR1 gene expression. We evaluated the effect of tryptanthrin on P-glycoprotein (P-gp)-mediated MDR in a breast cancer cell line MCF-7. Tryptanthrin could depress overexpression of MDR1 gene. We observed reduction of P-gp protein in parallel with decreases in mRNA in MCF-7/adr cells treated with tryptanthrin. Tryptanthrin suppressed the activity of MDR1 gene promoter. Tryptanthrin also enhanced interaction of the nuclear proteins with the negatively regulatory CAAT region of MDR1 gene promoter in MCF-7/adr. It might result in suppression of MDR1 gene. In addition, tryptanthrin decreased the amount of mutant p53 protein with decreasing mutant p53 protein stability. It might contribute to negative regulation of MDR1 gene. In conclusion, tryptanthrin exhibited MDR reversing effect by down-regulation of MDR1 gene and might be a new adjuvant agent for chemotherapy.

  12. Dioscin enhances methotrexate absorption by down-regulating MDR1 in vitro and in vivo

    SciTech Connect

    Wang, Lijuan; Wang, Changyuan; Peng, Jinyong; Liu, Qi; Meng, Qiang; Sun, Huijun; Huo, Xiaokui; and others

    2014-06-01

    The purpose of this study was to investigate the enhancing effect of dioscin on the absorption of methotrexate (MTX) and clarify the molecular mechanism involved in vivo and in vitro. Dioscin increased MTX chemosensitivity and transepithelial flux in the absorptive direction, significantly inhibiting multidrug resistance 1 (MDR1) mRNA and protein expression and MDR1 promoter and nuclear factor κ-B (NF-κB) activities in Caco-2 cells. Moreover, inhibitor κB-α (IκB-α) degradation was inhibited by dioscin. Dioscin enhanced the intracellular concentration of MTX by down-regulating MDR1 expression through a mechanism that involves NF-κB signaling pathway inhibition in Caco-2 cells. Dioscin strengthened MTX absorption by inhibiting MDR1 expression in rat intestine. In addition, even though MTX is absorbed into the enterocytes, there was no increase in toxicity observed, and that, in fact, decreased toxicity was seen. - Highlights: • Dioscin raised MTX concentration by inhibiting MDR1 in Caco-2 cells. • Dioscin suppresses MDR1 by inhibiting NF-κB signaling pathway in Caco-2 cells. • Dioscin can enhance MTX absorption via inhibiting MDR1 in vivo and in vitro. • Dioscin did not increase MTX-induced gastrointestinal mucosal toxicity.

  13. Orally administered extract from Prunella vulgaris attenuates spontaneous colitis in mdr1a-/- mice

    PubMed Central

    Haarberg, Kelley MK; Wymore Brand, Meghan J; Overstreet, Anne-Marie C; Hauck, Catherine C; Murphy, Patricia A; Hostetter, Jesse M; Ramer-Tait, Amanda E; Wannemuehler, Michael J

    2015-01-01

    AIM: To investigate the ability of a Prunella vulgaris (P. vulgaris) ethanolic extract to attenuate spontaneous typhlocolitis in mdr1a-/- mice. METHODS: Vehicle (5% ethanol) or P. vulgaris ethanolic extract (2.4 mg/d) were administered daily by oral gavage to mdr1a-/- or wild type FVBWT mice from 6 wk of age up to 20 wk of age. Clinical signs of disease were noted by monitoring weight loss. Mice experiencing weight loss in excess of 15% were removed from the study. At the time mice were removed from the study, blood and colon tissue were collected for analyses that included histological evaluation of lesions, inflammatory cytokine levels, and myeloperoxidase activity. RESULTS: Administration of P. vulgaris extracts to mdr1a-/- mice delayed onset of colitis and reduced severity of mucosal inflammation when compared to vehicle-treated mdr1a-/- mice. Oral administration of the P. vulgaris extract resulted in reduced (P < 0.05) serum levels of IL-10 (4.6 ± 2 vs 19.4 ± 4), CXCL9 (1319.0 ± 277 vs 3901.0 ± 858), and TNFα (9.9 ± 3 vs 14.8 ± 1) as well as reduced gene expression by more than two-fold for Ccl2, Ccl20, Cxcl1, Cxcl9, IL-1α, Mmp10, VCAM-1, ICAM, IL-2, and TNFα in the colonic mucosa of mdr1a-/- mice compared to vehicle-treated mdr1a-/- mice. Histologically, several microscopic parameters were reduced (P < 0.05) in P. vulgaris-treated mdr1a-/- mice, as was myeloperoxidase activity in the colon (2.49 ± 0.16 vs 3.36 ± 0.06, P < 0.05). The numbers of CD4+ T cells (2031.9 ± 412.1 vs 5054.5 ± 809.5) and germinal center B cells (2749.6 ± 473.7 vs 4934.0 ± 645.9) observed in the cecal tonsils of P. vulgaris-treated mdr1a-/- were significantly reduced (P < 0.05) from vehicle-treated mdr1a-/- mice. Vehicle-treated mdr1a-/- mice were found to produce serum antibodies to antigens derived from members of the intestinal microbiota, indicative of severe colitis and a loss of adaptive tolerance to the members of the microbiota. These serum antibodies were greatly

  14. Safety of fluralaner, a novel systemic antiparasitic drug, in MDR1(-/-) Collies after oral administration

    PubMed Central

    2014-01-01

    Background Fluralaner is a novel systemic ectoparasiticide for dogs providing long-acting flea- and tick-control after a single oral dose. This study investigated the safety of oral administration of fluralaner at 3 times the highest expected clinical dose to Multi Drug Resistance Protein 1 (MDR1(-/-)) gene defect Collies. Methods Sixteen Collies homozygous for the MDR1 deletion mutation were included in the study. Eight Collies received fluralaner chewable tablets once at a dose of 168 mg/kg; eight sham dosed Collies served as controls. All Collies were clinically observed until 28 days following treatment. Results No adverse events were observed subsequent to fluralaner treatment of MDR1(-/-) Collies at three times the highest expected clinical dose. Conclusions Fluralaner chewable tablets are well tolerated in MDR1(-/-) Collies following oral administration. PMID:24602342

  15. Fluorescent probes of the isoxazole-dihydropyridine scaffold: MDR-1 binding and homology model.

    PubMed

    Szabon-Watola, Monika I; Ulatowski, Sarah V; George, Kathleen M; Hayes, Christina D; Steiger, Scott A; Natale, Nicholas R

    2014-01-01

    Isoxazole-1,4-dihydropyridines (IDHPs) were tethered to fluorescent moieties using double activation via a lanthanide assisted Weinreb amidation. IDHP-fluorophore conjugate 3c exhibits the highest binding to date for IDHPs at the multidrug-resistance transporter (MDR-1), and IDHP-fluorophore conjugates 3c and 7 distribute selectively in SH-SY5Y cells. A homology model for IDHP binding at MDR-1 is presented which represents our current working hypothesis.

  16. MDR1 Synonymous Polymorphisms Alter Transporter Specificity and Protein Stability in a Stable Epithelial Monolayer

    PubMed Central

    Fung, King Leung; Pan, James; Ohnuma, Shinobu; Lund, Paul E.; Pixley, Jessica N.; Kimchi-Sarfaty, Chava; Ambudkar, Suresh V.; Gottesman, Michael M.

    2016-01-01

    The drug efflux function of P-glycoprotein (P-gp) encoded by MDR1 can be influenced by genetic polymorphisms, including two synonymous changes in the coding region of MDR1. Here we report that the conformation of P-gp and its drug efflux activity can be altered by synonymous polymorphisms in stable epithelial monolayers expressing P-gp. Several cell lines with similar MDR1 DNA copy number were developed and termed LLC-MDR1-WT (expresses wild-type P-gp), LLC-MDR1-3H (expresses common haplotype P-gp), and LLC-MDR1-3HA (a mutant that carries a different valine codon in position 3435). These cell lines express similar levels of recombinant mRNA and protein. P-gp in each case is localized on the apical surface of polarized cells. However, the haplotype and its mutant P-gps fold differently from the wild-type, as determined by UIC2 antibody shift assays and limited proteolysis assays. Surface biotinylation experiments suggest that the non-wild-type P-gps have longer recycling times. Drug transport assays show that wild-type and haplotype P-gp respond differently to P-gp inhibitors that block efflux of rhodamine-123 or mitoxantrone. In addition, cytotoxicity assays show that the LLC-MDR1-3H cells are more resistant to mitoxantrone than the LLC-MDR1-WT cells after being treated with a P-gp inhibitor. Expression of polymorphic P-gp, however, does not affect the host cell’s morphology, growth rate, or monolayer formation. Also, ATPase activity assays indicate that neither basal nor drug-stimulated ATPase activities are affected in the variant P-gps. Taken together, our findings indicate that “silent” polymorphisms significantly change P-gp function, which would be expected to affect interindividual drug disposition and response. PMID:24305879

  17. Relationship between the expression of MDR1 in hepatocellular cancer and its biological behaviors

    PubMed Central

    Gao, Bo; Yang, Feng-Mei; Yu, Zong-Tao; Li, Rui; Xie, Fei; Chen, Jie; Luo, Hai-Jun; Zhang, Ji-Cai

    2015-01-01

    Objective: By the detection of HBV infection, AFP and AST, the targets of biological behavior and the gene expression of multi-drug resistance gene 1 (MDR1) in hepatocellular carcinoma (HCC), we investigate characteristics of the expression of MDR1 in HCC and its relationship with HCC biological behavior. Methods: Using real-time fluorescence quantitative PCR (FQ-PCR) to detect the expressions of MDR1 in 102 samples of HCC tissue and 20 samples of non-cancerous tissue, we analyze the relationship between expressions of MDR1 and biological characteristics of HCC. Results: The expression of MDR1 in HCC is 0.55±0.27, and in normal liver tissues is 0.23±0.10, respectively. The expression in HCC is higher than it in normal liver tissue, the difference is statistically significant (P<0.05) and the difference between the expression and the HCC envelopes is statistically significant, and the expression increases along with the increase of Edmondson classification (P<0.05). HBV infection, AFP positive, the rise of AST, all these factors have positive correlations with the expression (r=0.463, 0.473, 0.299). In MDR1 expressions of HCC patients, the survival curve of the negative is higher than that of the positive, but the difference is not statistically significant. Conclusion: There are drug resistance phenomena in HCC, MDR1 expression may play an important role in primary HCC drug resistance. HBV infection can be detected as a reference indicator of HCC chemotherapy resistance, plasma levels of AFP, AST can be used as a reference index change dynamic monitoring of MDR1 expression. PMID:26261589

  18. Complete Knockout of Endogenous Mdr1 (Abcb1) in MDCK Cells by CRISPR-Cas9.

    PubMed

    Simoff, Ivailo; Karlgren, Maria; Backlund, Maria; Lindström, Anne-Christine; Gaugaz, Fabienne Z; Matsson, Pär; Artursson, Per

    2016-02-01

    Madin-Darby canine kidney II cells transfected with one or several transport proteins are commonly used models to study drug transport. In these cells, however, endogenous transporters such as canine Mdr1/P-glycoprotein (Abcb1) complicate the interpretation of transport studies. The aim of this investigation was to establish a Madin-Darby canine kidney II cell line using CRISPR-Cas9 gene-editing technology to knock out endogenous canine Mdr1 (cMdr1) expression. CRISPR-Cas9-mediated Abcb1 homozygous disruption occurred at frequencies of around 20% and resulted in several genotypes. We selected 1 clonal cell line, cMdr1 KO Cl2, for further examination. Consistent with an on-target effect of CRISPR-Cas9 in specific regions of the endogenous canine Abcb1 gene, we obtained a cell clone with Abcb1 gene alterations and without any cMdr1 expression, as confirmed by genome sequencing and quantitative protein analysis. Functional studies of these cells, using digoxin and other prototypic MDR1 substrates, showed close to identical transport in the apical-to-basolateral and basolateral-to-apical directions, resulting in efflux ratios indistinguishable from unity.

  19. Validation of a P-Glycoprotein (P-gp) Humanized Mouse Model by Integrating Selective Absolute Quantification of Human MDR1, Mouse Mdr1a and Mdr1b Protein Expressions with In Vivo Functional Analysis for Blood-Brain Barrier Transport

    PubMed Central

    Sadiq, Muhammad Waqas; Uchida, Yasuo; Hoshi, Yutaro; Tachikawa, Masanori; Terasaki, Tetsuya; Hammarlund-Udenaes, Margareta

    2015-01-01

    It is essential to establish a useful validation method for newly generated humanized mouse models. The novel approach of combining our established species-specific protein quantification method combined with in vivo functional studies is evaluated to validate a humanized mouse model of P-gp/MDR1 efflux transporter. The P-gp substrates digoxin, verapamil and docetaxel were administered to male FVB Mdr1a/1b(+/+) (FVB WT), FVB Mdr1a/1b(-/-) (Mdr1a/1b(-/-)), C57BL/6 Mdr1a/1b(+/+) (C57BL/6 WT) and humanized C57BL (hMDR1) mice. Brain-to-plasma total concentration ratios (Kp) were measured. Quantitative targeted absolute proteomic (QTAP) analysis was used to selectively quantify the protein expression levels of hMDR1, Mdr1a and Mdr1b in the isolated brain capillaries. The protein expressions of other transporters, receptors and claudin-5 were also quantified. The Kp for digoxin, verapamil, and docetaxel were 20, 30 and 4 times higher in the Mdr1a/1b(-/-) mice than in the FVB WT controls, as expected. The Kp for digoxin, verapamil and docetaxel were 2, 16 and 2-times higher in the hMDR1 compared to the C57BL/6 WT mice. The hMDR1 mice had 63- and 9.1-fold lower expressions of the hMDR1 and Mdr1a proteins than the corresponding expression of Mdr1a in C57BL/6 WT mice, respectively. The protein expression levels of other molecules were almost consistent between C57BL/6 WT and hMDR1 mice. The P-gp function at the BBB in the hMDR1 mice was smaller than that in WT mice due to lower protein expression levels of hMDR1 and Mdr1a. The combination of QTAP and in vivo functional analyses was successfully applied to validate the humanized animal model and evaluates its suitability for further studies. PMID:25932627

  20. MDR1 overexpression inhibits chemotherapy-induced toxicity of granulosa cells

    PubMed Central

    Salih, Sana M

    2011-01-01

    OBJECTIVE To protect granulosa cells from chemotherapy-induced toxicity by retrovirus-mediated multidrug resistance gene (MDR1) transfection. DESIGN Laboratory study. SETTING Academic research laboratory in a university hospital. INTERVENTION(S) KK15 immortalized murine granulosa cell line was transiently transduced with sf91m3 retrovirus vector carrying MDR1 cDNA that encodes P-glycoprtoein (P-gp). Transduced cells were selected with colchicine and treated with doxorubicin or paclitaxel for 24–72 hours. The expression and function of MDR1 and the mRNA expression of selected steroidogenesis enzymes were evaluated by flow cytometry, cell viability assays, Western blot, and RT-PCR. MAIN OUTCOME MEASURE(S) Viability of sf91m3-transduced KK15 cells after treatment with doxorubicin and paclitaxel. RESULT(S) sf91m3-transduced KK15 demonstrated high expression of biologically active MDR1 as shown by flow cytometry analysis and immunoblotting using P-gp monoclonal antibody and Rhodamine 123 efflux assays. sf91m3-transduced KK15 exhibited significant resistance to toxicity of 10uM paclitaxel(p≤0.001). MDR1-transduced KK15 cells were also protected from doxorubicin toxicity (10nM to 2.5uM) as shown by cell viability assay (p≤0.02). Both flow cytometry and cell viability assay showed that the protection of KK15 from doxorubicin toxicity was lost at 5 uM of doxorubicin; equivalent to 500 times LD50 (p≥0.05). sf91m3-transduced KK15 showed normal mRNA expression of a panel of selected steroidogenesis enzymes. CONCLUSION(S) Retroviral gene delivery of human MDR1 inhibited chemotherapy- induced granulosa cell toxicity and offered chemoprotection in an in vitro model. PMID:21316663

  1. Effects of alpha-adrenoceptor antagonist doxazosin on MDR1-mediated multidrug resistance and transcellular transport.

    PubMed

    Takara, Kohji; Sakaeda, Toshiyuki; Kakumoto, Mikio; Tanigawara, Yusuke; Kobayashi, Hironao; Okumura, Katsuhiko; Ohnishi, Noriaki; Yokoyama, Teruyoshi

    2009-01-01

    The purpose of this study is to examine the effects of doxazosin, an alpha-adrenoceptor antagonist, on P-glycoprotein/MDR1-mediated multidrug resistance (MDR) and the transport of anticancer drugs. The effects of doxazosin, prazosin, and terazosin on MDR1-mediated MDR were assessed in human cervical carcinoma HeLa cells and the MDR1-overexpressing derivative Hvrl00-6, established by stepwise increases of the vinblastine concentration in the culture medium. The effects of doxazosin on the transcellular transport and intracellular accumulation of [3H]vinblastine, [3H]daunorubicin, and [3H]digoxin, all MDR1 substrates, were evaluated using LLC-GA5-COL150 cell monolayers, established by transfection of human MDR1 cDNA into porcine kidney epithelial LLC-PK1 cells. The sensitivity to vinblastine and paclitaxel of Hvrl00-6 cells was increased at 3.4- and 17.5-fold, respectively, by the addition of 1 microM doxazosin, whereas prazosin and terazosin had weaker or no such effects. Prazosin at 1 microM had a reversal effect on the sensitivity to vinblastine, whereas terazosin had no effect. In transport experiments, doxazosin concentration dependently increased the apical-to-basal transport of radiolabeled drugs in LLC-GA5-COL150 cells, but did not show remarkable effects on the basal-to-apical transport. In addition, doxazosin restored the intracellular accumulation in a concentration-dependent manner in LLC-GA5-COL150 cells. Doxazosin may partly reverse MDR by inhibiting MDR1-mediated transport, making it a candidate lead compound in the development of a reversing agent for MDR.

  2. Identification of a Cryptic Bacterial Promoter in Mouse (mdr1a) P-Glycoprotein cDNA.

    PubMed

    Pluchino, Kristen M; Esposito, Dominic; Moen, Janna K; Hall, Matthew D; Madigan, James P; Shukla, Suneet; Procter, Lauren V; Wall, Vanessa E; Schneider, Thomas D; Pringle, Ian; Ambudkar, Suresh V; Gill, Deborah R; Hyde, Steven C; Gottesman, Michael M

    2015-01-01

    The efflux transporter P-glycoprotein (P-gp) is an important mediator of various pharmacokinetic parameters, being expressed at numerous physiological barriers and also in multidrug-resistant cancer cells. Molecular cloning of homologous cDNAs is an important tool for the characterization of functional differences in P-gp between species. However, plasmids containing mouse mdr1a cDNA display significant genetic instability during cloning in bacteria, indicating that mdr1a cDNA may be somehow toxic to bacteria, allowing only clones containing mutations that abrogate this toxicity to survive transformation. We demonstrate here the presence of a cryptic promoter in mouse mdr1a cDNA that causes mouse P-gp expression in bacteria. This expression may account for the observed toxicity of mdr1a DNA to bacteria. Sigma 70 binding site analysis and GFP reporter plasmids were used to identify sequences in the first 321 bps of mdr1a cDNA capable of initiating bacterial protein expression. An mdr1a M107L cDNA containing a single residue mutation at the proposed translational start site was shown to allow sub-cloning of mdr1a in E. coli while retaining transport properties similar to wild-type P-gp. This mutant mdr1a cDNA may prove useful for efficient cloning of mdr1a in E. coli.

  3. MDR1 Polymorphisms and Idiopathic Nephrotic Syndrome in Slovak Children: Preliminary Results

    PubMed Central

    Cizmarikova, Martina; Podracka, Ludmila; Klimcakova, Lucia; Habalova, Viera; Boor, Andrej; Mojzis, Jan; Mirossay, Ladislav

    2015-01-01

    Background The role of the multidrug resistance-1 (MDR1 or ABCB1) gene polymorphisms 1236T>C, 2677T>G, and 3435T>C was studied in relation to susceptibility, demographics, and pathological characteristics, as well as their role in the therapeutic response (TR) to prednisone treatment in children with idiopathic nephrotic syndrome (INS). Material/Methods The polymorphisms were analyzed using the polymerase chain reaction-restriction fragment length polymorphism method in 46 children with INS and in 100 healthy controls. Different genetic models (codominant, dominant, recessive, and overdominant) were used for testing of associations between polymorphisms and phenotypes. Results Statistical analysis showed a significantly increased chance of TR in children carrying 3435TC genotype (OR=5.13, 95% CI=1.18–22.25; overdominant model). Moreover, INS patients under 6 years of age had significantly decreased frequencies of MDR1 1236CC (7.7% vs. 35%, p=0.029) or 2677GG (3.8% vs. 30.0%, p=0.033) genotypes. We also observed that patients with minimal change in disease and patients under 6 years of age at the onset of INS were initial responders more frequently when compared with children with focal segmental glomerulosclerosis and patients ≥6 years old at the onset (p=0.0001, p=0.027, respectively). Conclusions These data suggest that prednisone TR may be influenced by histology, age at the onset of INS, and MDR1 3435T>C polymorphism. The MDR1 1236T>C and 2677T>G polymorphisms were significantly associated with age at onset. Larger multicenter studies and studies across other ethnic groups are needed to elucidate the contradictory implications of MDR1 polymorphisms with INS in children. PMID:25559283

  4. Cross-talk between signalling pathways and the multidrug resistant protein MDR-1

    PubMed Central

    Ding, S; Chamberlain, M; McLaren, A; Goh, L-b; Duncan, I; Wolf, C R

    2001-01-01

    The multidrug resistant protein MDR-1 has been associated with the resistance to a wide range of anti-cancer drugs. Taxol is a substrate for this transporter system and is used in the treatment of a wide range of human malignancies including lung, breast and ovarian cancer. We have generated a series of ovarian cell lines resistant to this compound, all of which overexpress MDR-1 through gene amplification. We present novel evidence that a constitutive activation of the ERK1/2 MAP kinase pathway was also observed although the level of active JNK and p38 remained unchanged. Inhibition of the ERK1/2 MAP kinase pathway using UO126 or PD098059 re-sensitised the Taxol resistant cells at least 20-fold. Importantly, when Mdr-1 cDNA was stably expressed in the wild-type cell line to generate a highly Taxol-resistant sub-line, 1847/MDR5, ERK1/2 MAP kinases again became activated. This result demonstrated that the increased activity of the signalling pathway in the Taxol-resistant lines was directly attributable to MDR-1 overexpression and was not due to the effects of Taxol itself. Additionally, we demonstrated that inhibition of the P13K pathway with LY294002 sensitised the MDR-1-expressing 1847/TX0.5 cells and 1847/MDR5 cells at least 10-fold but had no effect in the wild-type cells. This finding suggests a possible role for this pathway, also, in the generation of resistance to Taxol. © 2001 Cancer Research Campaign  http://www.bjcancer.com PMID:11710832

  5. Diindolylmethane, a naturally occurring compound, induces CYP3A4 and MDR1 gene expression by activating human PXR

    PubMed Central

    Pondugula, Satyanarayana R.; Flannery, Patrick C.; Abbott, Kodye L.; Coleman, Elaine S.; Mani, Sridhar; Samuel, Temesgen; Xie, Wen

    2015-01-01

    Activation of human pregnane X receptor (hPXR)-regulated expression of cytochrome P450 3A4 (CYP3A4) and multidrug resistance protein 1 (MDR1) plays an important role in mediating adverse drug interactions. Given the common use of natural products as part of adjunct human health behavior, there is a growing concern about natural products for their potential to induce undesired drug interactions through the activation of hPXR-regulated CYP3A4 and MDR1. Here, we studied whether 3,3′-diindolylmethane (DIM), a natural health supplement, could induce hPXR-mediated regulation of CYP3A4 and MDR1 in human hepatocytes and intestinal cells. DIM, at its physiologically relevant concentrations, not only induced hPXR transactivation of CYP3A4 promoter activity but also induced gene expression of CYP3A4 and MDR1. DIM decreased intracellular accumulation of MDR1 substrate rhodamine 123, suggesting that DIM induces the functional expression of MDR1. Pharmacologic inhibition or genetic knockdown of hPXR resulted in attenuation of DIM induced CYP3A4 and MDR1 gene expression, suggesting that DIM induces CYP3A4 and MDR1 in an hPXR-dependent manner. Together, these results support our conclusion that DIM induces hPXR-regulated CYP3A4 and MDR1 gene expression. The inductive effects of DIM on CYP3A4 and MDR1 expression caution the use of DIM in conjunction with other medications metabolized and transported via CYP3A4 and MDR1, respectively. PMID:25542144

  6. Nanolipoparticles-mediated MDR1 siRNA delivery reduces doxorubicin resistance in breast cancer cells and silences MDR1 expression in xenograft model of human breast cancer

    PubMed Central

    Nourbakhsh, Mahnaz; Jaafari, Mahmoud Reza; Lage, Hermann; Abnous, Khalil; mosaffa, Fatemeh; Badiee, Ali; Behravan, Javad

    2015-01-01

    Objective(s): P-glycoprotein (P-gp) is an efflux protein, the overexpression of which has been associated with multidrug resistance in various cancers. Although siRNA delivery to reverse P-gp expression may be promising for sensitizing of tumor cells to cytotoxic drugs, the therapeutic use of siRNA requires effective carriers that can deliver siRNA intracellularly with minimal toxicity on target cells. We investigated a special class of PEGylated lipid-based nanoparticles (NP), named nanolipoparticles (NLPs), for siRNA-mediated P-gp downregulation. Materials and Methods: NLPs were prepared based on low detergent dialysis method. After characterization, we evaluated the effect of NLPs on siRNA delivery, and P-gp downregulation compared to oligofectamine™ (OFA) in vitro and in vivo. Results: Our results showed a significant decrease in P-gp expression and subsequent enhancement of chemosensitivity to doxorubicin in vitro. Although the effectiveness of NLPs for in vitro siRNA delivery compared to OFA was limited, the results of in vivo studies showed noticeable effectiveness of NLPs for systemic siRNA delivery. siRNA delivery using NLPs could downregulate MDR1 in tumor cells more than 80%, while OFA had a reverse effect on MDR1 expression in vivo. Conclusion: The results indicated that the prepared NLPs could be suitable siRNA delivery systems for tumor therapy. PMID:26019802

  7. Use of polymerase chain reaction in the quantitation of mdr-1 gene expression

    SciTech Connect

    Murphy, L.D.; Herzog, C.E.; Rudick, J.B.; Fojo, A.T.; Bates, S.E. )

    1990-11-01

    The ability of the polymerase chain reaction (PCR) to quantitate expression of mRNA was examined in the present study. The model chosen was expression of the multidrug resistance gene mdr-1/Pgp in two colon carcinoma cell lines which express mdr-1/Pgp at levels comparable to those found in many clinical samples. PCR was utilized to evaluate differences in mdr-1/Pgp expression in the two cell lines after modulation by sodium butyrate. Thus, comparisons were made across a range of mdr-1/Pgp expression as well as comparisons of small differences. The PCR was found to be both sensitive and quantitative. Accurate quantitation requires demonstration of an exponential range which varies among samples. The exponential range can be determined by carrying out the PCR for a fixed number of cycles on serial dilutions of the RNA reverse transcription product, or by performing the reaction with a varying number of cycles on a fixed quantity of cDNA. By quantitation of the difference in PCR product derived from a given amount of RNA from the sodium butyrate treated and untreated cells, the difference in mRNA expression between samples can be determined. Normalization of the results can be achieved by independent amplification of a control gene, such as {beta}{sub 2}-microglobulin, when the latter is also evaluated in the exponential range. Simultaneous amplification of the control and target genes results in lower levels of PCR products due to competition, which varies from sample to sample. The PCR is thus a labor-intensive but sensitive method of quantitating gene expression in small samples of RNA.

  8. MDR1 gene expression enhances long-term engraftibility of cultured bone marrow cells

    SciTech Connect

    Rentala, Satyanarayana; Sagar Balla, Murali Mohan; Khurana, Satish; Mukhopadhyay, Asok . E-mail: asok@nii.res.in

    2005-09-30

    Primitive hematopoietic stem cells are responsible for long-term engraftment in irradiated host. Here, we report that multi-drug resistance 1 (mdr1) gene expressing primitive hematopoietic cells were multiplied in ex vivo culture, with the support of extracellular matrix components and cytokines. About 20-fold expansion of total nucleated cells was achieved in a 10-day culture. Lin{sup -}Sca-1{sup +} and long-term culture-initiating cells were increased by 54- and 26-fold, respectively. Expanded cells were long-term multi-lineage engraftible in sub-lethally irradiated mice. Donor-derived peripheral blood chimerism was significantly higher (73.2 {+-} 9.1%, p < 0.01) in expanded cells than in normal and 5-flurouracil-treated bone marrow cells. Most interestingly, the expression of mdr1 gene was significantly enhanced in cultured cells than in other two sources of donor cells. The mdr1 gene was functional since expanded cells effluxed Hoechst 33342 and Rh123 dyes. These results suggest that primitive engraftible stem cells can be expanded in the presence of suitable microenvironments.

  9. Autonomously replicating episomes contain mdr1 genes in a multidrugresistant human cell line

    SciTech Connect

    Ruiz, J.C.; Wahl, G.M.; Choi, K.; Roninson, I.B.; VonHoff, D.D.

    1989-01-01

    Gene amplification in human tumor cells is frequently mediated by extrachromosomal elements (e.g., double minute chromosomes (DMs)). Recent experiments have shown that DMs can be formed from smaller, submicroscopic circular precursors referred to as episomes. To investigate whether episomes are generally involved as intermediates in gene amplification, the authors determined whether they mediate the amplification of the mdr1 gene, which when overexpressed engenders cross resistance to multiple lipophilic drugs. A variety of methods including electrophoresis of undigested DNAs in high-voltage gradients, NotI digestion, and production of double-strand breaks by gamma radiation were used to distinguish between mdr1 sequences amplified on submicroscopic circular molecules and those amplified within DMs or chromosomal DNA. The gamma-irradiation procedure provides a new method for detecting and determining the size of circular molecules from 50 kilobases (kb) to greater than 1,000 kb. These methods revealed that some of the amplified mdr1 genes in vinblastine-resistant KB-V1 cells are contained in supercoiled circular molecules of --600 and --750 kb. Analysis of the replication of these molecules by a Meselson-Stahl density shift experiment demonstrated that they replicate approximately once in a cell cycle. The data lend further support to a model for gene amplification in which DMs are generally formed from smaller, autonomously replicating precursors.

  10. ΔNp73α regulates MDR1 expression by inhibiting p53 function

    PubMed Central

    Vilgelm, A; Wei, JX; Piazuelo, MB; Washington, MK; Prassolov, V; El-Rifai, W; Zaika, A

    2014-01-01

    The p73 protein is a transcription factor and member of the p53 protein family that expresses as a complex variety of isoforms. ΔNp73α is an N-terminally truncated isoform of p73. We found that ΔNp73 protein is upregulated in human gastric carcinoma suggesting that ΔNp73 may play an oncogenic role in these tumors. Although it has been shown that ΔNp73α inhibits apoptosis and counteracts the effect of chemotherapeutic drugs, the underlying mechanism by which this p73 isoform contributes to chemotherapeutic drug response remains to be explored. We found that ΔNp73α upregulates MDR1 mRNA and p-glycoprotein (p-gp), which is involved in chemotherapeutic drug transport. This p-gp upregulation was accompanied by increased p-gp functional activity in gastric cancer cells. Our data suggest that upregulation of MDR1 by ΔNp73α is mediated by interaction with p53 at the MDR1 promoter. PMID:17952118

  11. DeltaNp73alpha regulates MDR1 expression by inhibiting p53 function.

    PubMed

    Vilgelm, A; Wei, J X; Piazuelo, M B; Washington, M K; Prassolov, V; El-Rifai, W; Zaika, A

    2008-04-01

    The p73 protein is a transcription factor and member of the p53 protein family that expresses as a complex variety of isoforms. DeltaNp73alpha is an N-terminally truncated isoform of p73. We found that DeltaNp73 protein is upregulated in human gastric carcinoma suggesting that DeltaNp73 may play an oncogenic role in these tumors. Although it has been shown that DeltaNp73alpha inhibits apoptosis and counteracts the effect of chemotherapeutic drugs, the underlying mechanism by which this p73 isoform contributes to chemotherapeutic drug response remains to be explored. We found that DeltaNp73alpha upregulates MDR1 mRNA and p-glycoprotein (p-gp), which is involved in chemotherapeutic drug transport. This p-gp upregulation was accompanied by increased p-gp functional activity in gastric cancer cells. Our data suggest that upregulation of MDR1 by DeltaNp73alpha is mediated by interaction with p53 at the MDR1 promoter.

  12. Polymorphisms in DNA Repair Genes and MDR1 and the Risk for Non-Hodgkin Lymphoma

    PubMed Central

    Kim, Hee Nam; Kim, Nan Young; Yu, Li; Kim, Yeo-Kyeoung; Lee, Il-Kwon; Yang, Deok-Hwan; Lee, Je-Jung; Shin, Min-Ho; Park, Kyeong-Soo; Choi, Jin-Su; Kim, Hyeoung-Joon

    2014-01-01

    The damage caused by oxidative stress and exposure to cigarette smoke and alcohol necessitate DNA damage repair and transport by multidrug resistance-1 (MDR1). To explore the association between polymorphisms in these genes and non-Hodgkin lymphoma risk, we analyzed 15 polymorphisms of 12 genes in a population-based study in Korea (694 cases and 1700 controls). Four genotypes of DNA repair pathway genes (XRCC1 399 GA, OGG1 326 GG, BRCA1 871 TT, and WRN 787 TT) were associated with a decreased risk for NHL [odds ratio (OR)XRCC1 GA = 0.80, p = 0.02; OROGG1 GG = 0.70, p = 0.008; ORBRCA1 TT = 0.71, p = 0.048; ORWRN TT = 0.68, p = 0.01]. Conversely, the MGMT 115 CT genotype was associated with an increased risk for NHL (OR = 1.25, p = 0.04). In the MDR1 gene, the 1236 CC genotype was associated with a decreased risk for NHL (OR = 0.74, p = 0.04), and the 3435 CT and TT genotypes were associated with an increased risk (OR3435CT = 1.50, p < 0.0001; OR3435TT = 1.43, p = 0.02). These results suggest that polymorphisms in the DNA repair genes XRCC1, OGG1, BRCA1, WRN1, and MGMT and in the MDR1 gene may affect the risk for NHL in Korean patients. PMID:24756092

  13. Polymorphisms in DNA repair genes and MDR1 and the risk for non-Hodgkin lymphoma.

    PubMed

    Kim, Hee Nam; Kim, Nan Young; Yu, Li; Kim, Yeo-Kyeoung; Lee, Il-Kwon; Yang, Deok-Hwan; Lee, Je-Jung; Shin, Min-Ho; Park, Kyeong-Soo; Choi, Jin-Su; Kim, Hyeoung-Joon

    2014-04-21

    The damage caused by oxidative stress and exposure to cigarette smoke and alcohol necessitate DNA damage repair and transport by multidrug resistance-1 (MDR1). To explore the association between polymorphisms in these genes and non-Hodgkin lymphoma risk, we analyzed 15 polymorphisms of 12 genes in a population-based study in Korea (694 cases and 1700 controls). Four genotypes of DNA repair pathway genes (XRCC1 399 GA, OGG1 326 GG, BRCA1 871 TT, and WRN 787 TT) were associated with a decreased risk for NHL [odds ratio (OR)XRCC1 GA=0.80, p=0.02; OROGG1 GG=0.70, p=0.008; ORBRCA1 TT=0.71, p=0.048; ORWRN TT=0.68, p=0.01]. Conversely, the MGMT 115 CT genotype was associated with an increased risk for NHL (OR=1.25, p=0.04). In the MDR1 gene, the 1236 CC genotype was associated with a decreased risk for NHL (OR=0.74, p=0.04), and the 3435 CT and TT genotypes were associated with an increased risk (OR3435CT=1.50, p<0.0001; OR3435TT=1.43, p=0.02). These results suggest that polymorphisms in the DNA repair genes XRCC1, OGG1, BRCA1, WRN1, and MGMT and in the MDR1 gene may affect the risk for NHL in Korean patients.

  14. MDR1/ABCB1 gene polymorphisms in patients with chronic myeloid leukemia

    PubMed Central

    Lardo, Mabel; Castro, Marcelo; Moiraghi, Beatriz; Rojas, Francisca; Borda, Natalia; Rey, Jorge A

    2015-01-01

    Background Tyrosine kinase inhibitors (TKIs) are the recommended treatment for patients with chronic myeloid leukemia (CML). The MDR1/ABCB1 gene plays a role in resistance to a wide spectrum of drugs, including TKIs. However, the association of MDR1/ABCB1 gene polymorphisms (SNPs) such as C1236T, G2677T/A, and C3435T with the clinical therapeutic evolution of CML has been poorly studied. We investigated these gene polymorphisms in CML-patients treated with imatinib, nilotinib and/or dasatinib. Methods ABCB1-SNPs were studied in 22 CML-patients in the chronic phase (CP) and 2 CML-patients in blast crisis (BC), all of whom were treated with TKIs, and compared with 25 healthy controls using nested-PCR and sequencing techniques. Results Seventeen different haplotypes were identified: 7 only in controls, 6 only in CML-patients, and the remaining 4 in both groups. The distribution ratios of homozygous TT-variants present on each exon between controls and CML-patients were 2.9 for exon 12, and 0.32 for the other 2 exons. Heterozygous T-variants were observed in all controls (100%) and 75% of CML-patients. Wt-haplotype (CC-GG-CC) was observed in 6 CML-patients (25%). In this wt-group, two were treated with nilotinib and reached a major molecular response. The remaining 4 cases had either a minimal or null molecular response, or developed bone marrow aplasia. Conclusion Our results suggest that SNPs of the MDR1/ABCB1 gene could help to characterize the prognosis and the clinical-therapeutic evolution of CML-patients treated with TKIs. Wt-haplotype could be associated with a higher risk of developing CML, and a worse clinical-therapeutic evolution. PMID:26457282

  15. Autonomously replicating episomes contain mdr1 genes in a multidrug-resistant human cell line.

    PubMed

    Ruiz, J C; Choi, K H; von Hoff, D D; Roninson, I B; Wahl, G M

    1989-01-01

    Gene amplification in human tumor cells is frequently mediated by extrachromosomal elements (e.g., double minute chromosomes [DMs]). Recent experiments have shown that DMs can be formed from smaller, submicroscopic circular precursors referred to as episomes (S. M. Carroll, M. L. DeRose, P. Gaudray, C. M. Moore, D. R. Needham-Vandevanter, D. D. Von Hoff and G. M. Wahl, Mol. Biol. 8:1525-1533, 1988). To investigate whether episomes are generally involved as intermediates in gene amplification, we determined whether they mediate the amplification of the mdr1 gene, which when overexpressed engenders cross resistance to multiple lipophilic drugs. A variety of methods including electrophoresis of undigested DNAs in high-voltage gradients, NotI digestion, and production of double-strand breaks by gamma irradiation were used to distinguish between mdr1 sequences amplified on submicroscopic circular molecules and those amplified within DMs or chromosomal DNA. The gamma-irradiation procedure provides a new method for detecting and determining the size of circular molecules from 50 kilobases (kb) to greater than 1,000 kb. These methods revealed that some of the amplified mdr1 genes in vinblastine-resistant KB-V1 cells are contained in supercoiled circular molecules of approximately 600 and approximately 750 kb. Analysis of the replication of these molecules by a Meselson-Stahl density shift experiment demonstrated that they replicate approximately once in a cell cycle. The data lend further support to a model for gene amplification in which DMs are generally formed from smaller, autonomously replicating precursors.

  16. MDR1 polymorphisms are associated with inflammatory bowel disease in a cohort of Croatian IBD patients

    PubMed Central

    2013-01-01

    Background Inflammatory bowel diseases (IBD) are chronic diseases of unknown etiology and pathogenesis in which genetic factors contribute to development of disease. MDR1/ABCB1 is an interesting candidate gene for IBD. The role of two single nucleotide polymorphisms, C3435T and G2677T remains unclear due to contradictory results of current studies. Thus, the aims of this research were to investigate the association of MDR1 polymorphisms, C3435T and G2677T, and IBD. Methods A total of 310 IBD patients, 199 Crohn's disease (CD) patients and 109 ulcerative colitis (UC) patients, and 120 healthy controls were included in the study. All subjects were genotyped for G2677T/A and C3435T polymorphism using RT-PCR. In IBD patients, review of medical records was performed and patients were phenotyped according to the Montreal classification. Results Significantly higher frequency of 2677T allele (p = 0.05; OR 1.46, 95% CI (1.0-2.14)) and of the 3435TT genotype was observed among UC patients compared to controls (p = 0.02; OR 2.12; 95% CI (1.11-4.03). Heterozygous carriers for C3435T were significantly less likely to have CD (p = 0.02; OR 0.58, 95% CI (0.36-0.91)). Haplotype analysis revealed that carriers of 3435T/2677T haplotype had a significantly higher risk of having UC (p = 0.02; OR 1.55; 95% CI (1.06-2.28)). Conclusion MDR1 polymorphisms are associated with both CD and UC with a stronger association with UC. PMID:23537364

  17. The multidrug resistance (mdr1) gene product functions as an ATP channel.

    PubMed Central

    Abraham, E H; Prat, A G; Gerweck, L; Seneveratne, T; Arceci, R J; Kramer, R; Guidotti, G; Cantiello, H F

    1993-01-01

    The multidrug resistance (mdr1) gene product, P-glycoprotein, is responsible for the ATP-dependent extrusion of a variety of compounds, including chemotherapeutic drugs, from cells. The data presented here show that cells with increased levels of the P-glycoprotein release ATP to the medium in proportion to the concentration of the protein in their plasma membrane. Furthermore, measurements of whole-cell and single-channel currents with patch-clamp electrodes indicate that the P-glycoprotein serves as an ATP-conducting channel in the plasma membrane. These findings suggest an unusual role for the P-glycoprotein. PMID:7678345

  18. Influence of MDR1 methylation on the curative effect of interventional embolism chemotherapy for cervical cancer

    PubMed Central

    Huang, Zhi; Zhang, Shuai; Shen, Yaping; Liu, Weixin; Long, Jipu; Zhou, Shi

    2016-01-01

    Background Multi-drug resistance (MDR) is the main cause of tumor failure to chemotherapy. This study aims to explore the influence of MDR1 methylation on curative effect of interventional embolism chemotherapy for cervical cancer. Methods Sixty-seven patients with cervical cancer receiving embolism chemotherapy were selected, and 45 normal cervical tissues were included as a control. Immunohistochemistry was used to detect the level of P-glycoprotein (P-gp) in cervical cancer, and to make an analysis compared with normal tissues. The methylation status of the MDR1 gene promoter region 16 CpG units was analyzed by using kilobase-specific cracking and matrix-assisted laser desorption ionization time of flight mass spectrometry. Results The results indicated that the positive expression rates of P-gp were 0% (0/45) in normal cervical tissue, and 61.19% (41/67) and 77.61% (52/67) before and after interventional embolism chemotherapy in cervical cancer tissues, respectively. There were significant differences compared with normal cervical tissues (χ2=4.2523, 0.0392). The positive expression rate of P-gp before chemotherapy was negatively correlated with efficacy of chemotherapy (r=−0.340, P=0.005). Methylation rate of 13 CpG units in normal tissues was significantly greater than cervical tissues (P<0.05). In cervical cancer tissue, methylation rate of six CpG units before interventional embolism chemotherapy was higher than after chemotherapy, but that of one CpG unit was lower than after chemotherapy (P<0.05). The methylation rate of one CpG unit with effective chemotherapy before chemotherapy was significantly higher than ineffective chemotherapy (P<0.05), and the other CpG units were similar (P>0.05). Conclusion P-gp expression level coded by MDR1, methylation status of partial MDR1 gene promoter regions CpG island, is closely related to the efficacy of interventional embolism chemotherapy for cervical cancer before the operation. PMID:26929635

  19. Physiological oxygen tensions modulate expression of the mdr1b multidrug-resistance gene in primary rat hepatocyte cultures.

    PubMed Central

    Hirsch-Ernst, K I; Kietzmann, T; Ziemann, C; Jungermann, K; Kahl, G F

    2000-01-01

    P-Glycoprotein transporters encoded by mdr1 (multidrug resistance) genes mediate extrusion of an array of lipophilic xenobiotics from the cell. In rat liver, mdr transcripts have been shown to be expressed mainly in hepatocytes of the periportal region. Since gradients in oxygen tension (pO(2)) may contribute towards zonated gene expression, the influence of arterial and venous pO(2) on mRNA expression of the mdr1b isoform was examined in primary rat hepatocytes cultured for up to 3 days. Maximal mdr1b mRNA levels (100%) were observed under arterial pO(2) after 72 h, whereas less than half-maximal mRNA levels (40%) were attained under venous pO(2). Accordingly, expression of mdr protein and extrusion of the mdr1 substrate rhodamine 123 were maximal under arterial pO(2) and reduced under venous pO(2). Oxygen-dependent modulation of mdr1b mRNA expression was prevented by actinomycin D, indicating transcriptional regulation. Inhibition of haem synthesis by 25 microM CoCl(2) blocked mdr1b mRNA expression under both oxygen tensions, whereas 80 microM desferrioxamine abolished modulation by O(2). Haem (10 microM) increased mdr1b mRNA levels under arterial and venous pO(2). In hepatocytes treated with 50 microM H(2)O(2), mdr1b mRNA expression was elevated by about 1.6-fold at venous pO(2) and 1.5-fold at arterial pO(2). These results support the conclusion that haem proteins are crucial for modulation of mdr1b mRNA expression by O(2) in hepatocyte cultures and that reactive oxygen species may participate in O(2)-dependent signal transduction. Furthermore, the present study suggests that oxygen might be a critical modulator for zonated secretion of mdr1 substrates into the bile. PMID:10947958

  20. Does maternal MDR1 C1236T polymorphism have an effect on placental arsenic levels?

    PubMed

    Kaya-Akyüzlü, Dilek; Kayaaltı, Zeliha; Doğan, Derya; Söylemezoğlu, Tülin

    2016-01-01

    To detect whether maternal MDR1 C1236T polymorphism has an effect on placental arsenic levels, 112 mother-placenta pairs were examined. Venous blood samples from mothers were collected to investigate the C1236T polymorphism which was detected by standard PCR-RFLP technique. Placentas were collected to measure arsenic levels by GF-AAS. The MDR1 C1236T genotype frequencies of mothers were found as 30.3% homozygote typical (CC), 51.8% heterozygote (CT) and 17.9% homozygote atypical (TT). The mean placental arsenic level was 62.36±30.43 μg/kg. It was observed that the placental arsenic concentrations were higher in mothers with TT genotype than those with CC and CT genotypes, but this was not statistically significant (p=0.702). This finding was indicated that fetuses of mothers with TT genotype may be more susceptible to arsenic toxicity as compared to those of with CC and CT genotypes. We believe that this difference warrant further studies with larger study subjects.

  1. Modulation of MDR1 and MRP3 Gene Expression in Lung Cancer Cells after Paclitaxel and Carboplatin Exposure

    PubMed Central

    Melguizo, Consolación; Prados, Jose; Luque, Raquel; Ortiz, Raúl; Caba, Octavio; Álvarez, Pablo J.; Gonzalez, Beatriz; Aranega, Antonia

    2012-01-01

    Carboplatin-paclitaxel is a reference regimen in the treatment of locally advanced or disseminated non-small cell lung cancer (NSCLC). This paper discusses the multidrug resistance developed with this drug combination, which is one of the major obstacles to successful treatment. In order to understand and overcome the drug resistance pattern of NSCLC after carboplatin plus paclitaxel exposure, levels of mRNA expression of multidrug resistance 1 (MDR1) and multidrug resistance-associated protein 3 (MRP3) were investigated in primary NSCLC cell lines (A-549 and A-427) and a metastasis-derived NSCLC cell line (NODO). Our results showed that exposure of the three NSCLC lines to plasma concentrations of paclitaxel (5 μM) produced an increase in MDR1 expression, while MRP3 showed no alteration in expression. By contrast, the same cells exposed to carboplatin plasma concentrations (30 μM) showed overexpression of MRP3. In these cells, MDR1 showed no expression changes. Interestingly, the combination of both paclitaxel and carboplatin caused increased expression of the MDR1 drug resistance gene rather than the individual treatments. These results suggest that carboplatin and paclitaxel may induce drug resistance mediated by MDR1 and MRP3, which may be enhanced by the simultaneous use of both drugs. PMID:23443122

  2. Characterization of intestinal inflammation and identification of related gene expression changes in mdr1a−/− mice

    PubMed Central

    Dommels, Y. E.M.; Zhu, S.; Davy, M.; Martell, S.; Hedderley, D.; Barnett, M. P.G.; McNabb, W. C.; Roy, N. C.

    2007-01-01

    Multidrug resistance targeted mutation (mdr1a−/−) mice spontaneously develop intestinal inflammation. The aim of this study was to further characterize the intestinal inflammation in mdr1a−/− mice. Intestinal samples were collected to measure inflammation and gene expression changes over time. The first signs of inflammation occurred around 16 weeks of age and most mdr1a−/− mice developed inflammation between 16 and 27 weeks of age. The total histological injury score was the highest in the colon. The inflammatory lesions were transmural and discontinuous, revealing similarities to human inflammatory bowel diseases (IBD). Genes involved in inflammatory response pathways were up-regulated whereas genes involved in biotransformation and transport were down-regulated in colonic epithelial cell scrapings of inflamed mdra1−/− mice at 25 weeks of age compared to non-inflamed FVB mice. These results show overlap to human IBD and strengthen the use of this in vivo model to study human IBD. The anti-inflammatory regenerating islet-derived genes were expressed at a lower level during inflammation initiation in non-inflamed colonic epithelial cell scrapings of mdr1a−/− mice at 12 weeks of age. This result suggests that an insufficiently suppressed immune response could be crucial to the initiation and development of intestinal inflammation in mdr1a−/− mice. PMID:18850176

  3. Role of hypoxia-inducible factor-{alpha} in hepatitis-B-virus X protein-mediated MDR1 activation

    SciTech Connect

    Han, Hyo-Kyung; Han, Chang Yeob; Cheon, Eun-Pa; Lee, Jaewon; Kang, Keon Wook . E-mail: kwkang@chosun.ac.kr

    2007-06-01

    The transition from chemotherapy-responsive cancer cells to chemotherapy-resistant cancer cells is mainly accompanied by the increased expression of multi-drug resistance 1 (MDR1). We found that hepatitis-B-virus X protein (HBx) increases the transcriptional activity and protein level of MDR1 in a hepatoma cell line, H4IIE. In addition, HBx overexpression made H4IIE cells more resistant to verapamil-uptake. HBx stabilized hypoxia-inducible factor-1{alpha} (HIF-1{alpha}) and induced the nuclear translocation of C/EBP{beta}. Reporter gene analyses showed that HBx increased the reporter activity in the cells transfected with the reporter containing MDR1 gene promoter. Moreover, the luciferase reporter gene activity was significantly inhibited by HIF-1{alpha} siRNA but not by overexpression of C/EBP dominant negative mutant. These results imply that HBx increases the MDR1 transporter activity through the transcriptional activation of the MDR1 gene with HIF-1{alpha} activation, and suggest HIF-1{alpha} for the therapeutic target of HBV-mediated chemoresistance.

  4. NOX1 mediates chemoresistance via HIF1α/MDR1 pathway in gallbladder cancer.

    PubMed

    Zhan, Ming; Wang, Hui; Chen, Tao; Chen, Wei; Yang, Linhua; He, Min; Xu, Sunwang; Wang, Jian

    NADPH oxidase 1 (NOX1) plays a key role in tumorigenesis and metastasis through generating reactive oxygen species (ROS), an important intracellular signaling molecule. However, how it is expressed in gallbladder cancer (GBC) tissue sample and whether it associates with GBC chemoresistance have never been investigated. Our study analyzed the relationship between NOX1 expression and cisplatin-sensitivity both in vivo and in vitro. We found that reduced NOX1 expression promoted cisplatin efficiency in GBC-SD cells, whereas overexpression of which potentially inhibited the sensitivity of cisplatin in SGC-996 cells. Further study into the mechanism we found that increased NOX1 expression elevated intracellular ROS levels, which then activated HIF-1α/MDR1 pathway. These findings established NOX1 a novel accelerant of chemoresistance in GBC, and NOX1-targeted therapeutics might be exploited as a strategy for increasing the efficacy of cisplatin treatment.

  5. NOX1 mediates chemoresistance via HIF1α/MDR1 pathway in gallbladder cancer.

    PubMed

    Zhan, Ming; Wang, Hui; Chen, Tao; Chen, Wei; Yang, Linhua; He, Min; Xu, Sunwang; Wang, Jian

    NADPH oxidase 1 (NOX1) plays a key role in tumorigenesis and metastasis through generating reactive oxygen species (ROS), an important intracellular signaling molecule. However, how it is expressed in gallbladder cancer (GBC) tissue sample and whether it associates with GBC chemoresistance have never been investigated. Our study analyzed the relationship between NOX1 expression and cisplatin-sensitivity both in vivo and in vitro. We found that reduced NOX1 expression promoted cisplatin efficiency in GBC-SD cells, whereas overexpression of which potentially inhibited the sensitivity of cisplatin in SGC-996 cells. Further study into the mechanism we found that increased NOX1 expression elevated intracellular ROS levels, which then activated HIF-1α/MDR1 pathway. These findings established NOX1 a novel accelerant of chemoresistance in GBC, and NOX1-targeted therapeutics might be exploited as a strategy for increasing the efficacy of cisplatin treatment. PMID:26545779

  6. Differential requirement of the transcription factor Mcm1 for activation of the Candida albicans multidrug efflux pump MDR1 by its regulators Mrr1 and Cap1.

    PubMed

    Mogavero, Selene; Tavanti, Arianna; Senesi, Sonia; Rogers, P David; Morschhäuser, Joachim

    2011-05-01

    Overexpression of the multidrug efflux pump Mdr1 causes increased fluconazole resistance in the pathogenic yeast Candida albicans. The transcription factors Mrr1 and Cap1 mediate MDR1 upregulation in response to inducing stimuli, and gain-of-function mutations in Mrr1 or Cap1, which render the transcription factors hyperactive, result in constitutive MDR1 overexpression. The essential MADS box transcription factor Mcm1 also binds to the MDR1 promoter, but its role in inducible or constitutive MDR1 upregulation is unknown. Using a conditional mutant in which Mcm1 can be depleted from the cells, we investigated the importance of Mcm1 for MDR1 expression. We found that Mcm1 was dispensable for MDR1 upregulation by H2O2 but was required for full MDR1 induction by benomyl. A C-terminally truncated, hyperactive Cap1 could upregulate MDR1 expression both in the presence and in the absence of Mcm1. In contrast, a hyperactive Mrr1 containing a gain-of-function mutation depended on Mcm1 to cause MDR1 overexpression. These results demonstrate a differential requirement for the coregulator Mcm1 for Cap1- and Mrr1-mediated MDR1 upregulation. When activated by oxidative stress or a gain-of-function mutation, Cap1 can induce MDR1 expression independently of Mcm1, whereas Mrr1 requires either Mcm1 or an active Cap1 to cause overexpression of the MDR1 efflux pump. Our findings provide more detailed insight into the molecular mechanisms of drug resistance in this important human fungal pathogen. PMID:21343453

  7. Intracellular targeted co-delivery of shMDR1 and gefitinib with chitosan nanoparticles for overcoming multidrug resistance

    PubMed Central

    Yu, Xiwei; Yang, Guang; Shi, Yijie; Su, Chang; Liu, Ming; Feng, Bo; Zhao, Liang

    2015-01-01

    Nowadays, multidrug resistance and side effects of drugs limit the effectiveness of chemotherapies in clinics. P-glycoprotein (P-gp) (MDR1), as a member of the ATP-binding cassette family, acts on transporting drugs into cell plasma across the membrane of cancer cells and leads to the occurrence of multidrug resistance, thus resulting in the failure of chemotherapy in cancer. The main aims of this research were to design a nanodelivery system for accomplishing the effective co-delivery of gene and antitumor drug and overcoming multidrug resistance effect. In this study, shMDR1 and gefitinib-encapsulating chitosan nanoparticles with sustained release, small particle size, and high encapsulation efficiency were prepared. The serum stability, protection from nuclease, and transfection efficiency of gene in vitro were investigated. The effects of co-delivery of shMDR1 and gefitinib in nanoparticles on reversing multidrug resistance were also evaluated by investigating the cytotoxicity, cellular uptake mechanism, and cell apoptosis on established gefitinib-resistant cells. The results demonstrated that chitosan nanoparticles entrapping gefitinib and shMDR1 had the potential to overcome the multidrug resistance and improve cancer treatment efficacy, especially toward resistant cells. PMID:26648717

  8. Intracellular targeted co-delivery of shMDR1 and gefitinib with chitosan nanoparticles for overcoming multidrug resistance.

    PubMed

    Yu, Xiwei; Yang, Guang; Shi, Yijie; Su, Chang; Liu, Ming; Feng, Bo; Zhao, Liang

    2015-01-01

    Nowadays, multidrug resistance and side effects of drugs limit the effectiveness of chemotherapies in clinics. P-glycoprotein (P-gp) (MDR1), as a member of the ATP-binding cassette family, acts on transporting drugs into cell plasma across the membrane of cancer cells and leads to the occurrence of multidrug resistance, thus resulting in the failure of chemotherapy in cancer. The main aims of this research were to design a nanodelivery system for accomplishing the effective co-delivery of gene and antitumor drug and overcoming multidrug resistance effect. In this study, shMDR1 and gefitinib-encapsulating chitosan nanoparticles with sustained release, small particle size, and high encapsulation efficiency were prepared. The serum stability, protection from nuclease, and transfection efficiency of gene in vitro were investigated. The effects of co-delivery of shMDR1 and gefitinib in nanoparticles on reversing multidrug resistance were also evaluated by investigating the cytotoxicity, cellular uptake mechanism, and cell apoptosis on established gefitinib-resistant cells. The results demonstrated that chitosan nanoparticles entrapping gefitinib and shMDR1 had the potential to overcome the multidrug resistance and improve cancer treatment efficacy, especially toward resistant cells. PMID:26648717

  9. Contribution of mdr1b-type P-glycoprotein to okadaic acid resistance in rat pituitary GH3 cells.

    PubMed

    Ritz, V; Marwitz, J; Sieder, S; Ziemann, C; Hirsch-Ernst, K I; Quentin, I; Steinfelder, H J

    1999-08-01

    Okadaic acid as well as other, structurally different, inhibitors of serine/threonine phosphatases 1 and 2A induce apoptosis in pituitary GH3 cells. Incubation with stepwise raised concentrations of okadaic acid resulted in the isolation of cells that were increasingly less sensitive to the cytotoxic effect of this agent. After about 18 months cells were selected that survived at 300 nM okadaic acid, which is about 30 times the initially lethal concentration. This study revealed that a major pharmacokinetic mechanism underlying cell survival was the development of a P-glycoprotein-mediated multidrug resistance (MDR) phenotype. The increase in mRNA levels of the mdr1b P-glycoprotein isoform correlated with the extent of drug resistance. Functional assays revealed that increasing drug resistance was paralleled by a decreased accumulation of rhodamine 123, a fluorescent dye which is a substrate of mdr1-mediated efflux activity. Resistance could be abolished by structurally different chemosensitizers of P-glycoprotein function like verapamil and reserpine but not by the leukotriene receptor antagonist MK571 which is a modulator of the multidrug resistance-associated protein (MRP). Okadaic acid resistance included cross-resistance to other cytotoxic agents that are substrates of mdr1-type P-glycoproteins, like doxorubicin and actinomycin D, but not to non-substrates of mdr1, e.g. cytosine arabinoside. Thus, functional as well as biochemical features support the conclusion that okadaic acid is a substrate of the mdr1-mediated efflux activity in rat pituitary GH3 cells. Maintenance of resistance after withdrawal of okadaic acid as well as metaphase spreads of 100 nM okadaic acid-resistant cells suggested a stable MDR genotype without indications for the occurrence of extrachromosomal amplifications, e.g. double minute chromosomes.

  10. Elevated expression of hepatic proliferative markers during early hepatocarcinogenesis in hepatitis-B virus transgenic mice lacking mdr1a-encoded P-glycoprotein.

    PubMed

    Bao, J J; Lee, B P; Stephens, L C; Sahin, A A; Van, N T; Johnston, D A; Ou, C N; Kuo, M T

    2000-10-01

    Recent studies have shown that expression levels of the multidrug resistance gene MDR1, which encodes the drug transporter P-glycoprotein, correlate with prognostic outcomes of certain tumor types. These findings suggest that expression of MDR1 may affect tumor behaviors. To address this issue further, we investigated the expression of mdr1a, a human MDR1 homolog, on the development of hepatocellular carcinoma in a transgenic mouse model carrying the liver-targeted expression of human hepatitis-B virus (HBV) surface antigen. The pathogenetic program was compared in HBV mice carrying either mdr1a(+/+) or mdr1a(-/-). We found that the expressions of proliferative activity markers, Ki67 nuclear antigen, and proliferating cell nuclear antigen were elevated in mdr1a(-/-) mice younger than 10 wk in comparison with those in the same age group of wild-type animals. Replication in the hepatic population as determined by bromodeoxyuridine incorporation tended to support observation that mdr1a(-/-) mice exhibited elevated labeling indices in this age group. Moreover, histologic staining and flow-cytometric analysis showed that the mdr1a(-/-) animals exhibited a higher cell population with polyploidy than did the mdr1a(+/+) counterparts of the same age. However, no significant differences in the expression of the liver-injury markers serum alanine transaminase and aspartate transaminase were observed. Although our results showed that absence of mdr1a expression is correlated with modest enhanced proliferative characteristics in the livers at stage before the development of hepatocellular carcinoma, the overall life spans between these two strains of mice were not significantly different. The implication of these findings to the role of P-glycoprotein in tumor development and cancer chemotherapy is discussed.

  11. MDR1 siRNA loaded hyaluronic acid-based CD44 targeted nanoparticle systems circumvent paclitaxel resistance in ovarian cancer

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoqian; Lyer, Arun K.; Singh, Amit; Choy, Edwin; Hornicek, Francis J.; Amiji, Mansoor M.; Duan, Zhenfeng

    2015-02-01

    Development of multidrug resistance (MDR) is an almost universal phenomenon in patients with ovarian cancer, and this severely limits the ultimate success of chemotherapy in the clinic. Overexpression of the MDR1 gene and corresponding P-glycoprotein (Pgp) is one of the best known MDR mechanisms. MDR1 siRNA based strategies were proposed to circumvent MDR, however, systemic, safe, and effective targeted delivery is still a major challenge. Cluster of differentiation 44 (CD44) targeted hyaluronic acid (HA) based nanoparticle has been shown to successfully deliver chemotherapy agents or siRNAs into tumor cells. The goal of this study is to evaluate the ability of HA-PEI/HA-PEG to deliver MDR1 siRNA and the efficacy of the combination of HA-PEI/HA-PEG/MDR1 siRNA with paclitaxel to suppress growth of ovarian cancer. We observed that HA-PEI/HA-PEG nanoparticles can efficiently deliver MDR1 siRNA into MDR ovarian cancer cells, resulting in down-regulation of MDR1 and Pgp expression. Administration of HA-PEI/HA-PEG/MDR1 siRNA nanoparticles followed by paclitaxel treatment induced a significant inhibitory effect on the tumor growth, decreased Pgp expression and increased apoptosis in MDR ovarian cancer mice model. Our findings suggest that CD44 targeted HA-PEI/HA-PEG/MDR1 siRNA nanoparticles can serve as a therapeutic tool with great potentials to circumvent MDR in ovarian cancer.

  12. Relationship between the expression of cyclooxygenase 2 and MDR1/P-glycoprotein in invasive breast cancers and their prognostic significance

    PubMed Central

    Surowiak, Pawel; Materna, Verena; Matkowski, Rafal; Szczuraszek, Katarzyna; Kornafel, Jan; Wojnar, Andrzej; Pudelko, Marek; Dietel, Manfred; Denkert, Carsten; Zabel, Maciej; Lage, Hermann

    2005-01-01

    Introduction Recent reports suggest that expression of the cyclooxygenase 2 (COX-2) enzyme may up-regulate expression of MDR1/P-glycoprotein (MDR1/P-gp), an exponent of resistance to cytostatic drugs. The present study aimed at examining the relationship between the expression of COX-2 and of MDR1/P-gp in a group of breast cancer cases. Methods Immunohistochemical reactions were performed using monoclonal antibodies against COX-2 and MDR1/P-gp on samples originating from 104 cases of primary invasive breast cancer. Results COX-2-positive cases were shown to demonstrate higher expression of MDR1/P-gp (P < 0.0001). The studies also demonstrate that COX-2 expression was typical for cases of a higher grade (P = 0.01), a shorter overall survival time (P < 0.0001) and a shorter progression-free time (P < 0.0001). In the case of MDR1/P-gp, its higher expression characterised cases of a higher grade (P < 0001), with lymph node involvement (P < 0001), and shorter overall survival (P < 0.0001) and progression-free time (P < 0.0001). Conclusion Our studies confirmed the unfavourable prognostic significance of COX-2 and MDR1/P-gp. We also document a relationship between COX-2 and MDR1/P-gp, which suggests that COX-2 inhibitors should be investigated in trials as a treatment supplementary to chemotherapy of breast cancers. PMID:16168133

  13. MDR-1 and MRP2 Gene Polymorphisms in Mexican Epileptic Pediatric Patients with Complex Partial Seizures

    PubMed Central

    Escalante-Santiago, David; Feria-Romero, Iris Angélica; Ribas-Aparicio, Rosa María; Rayo-Mares, Dario; Fagiolino, Pietro; Vázquez, Marta; Escamilla-Núñez, Consuelo; Grijalva-Otero, Israel; López-García, Miguel Angel; Orozco-Suárez, Sandra

    2014-01-01

    Although the Pgp efflux transport protein is overexpressed in resected tissue of patients with epilepsy, the presence of polymorphisms in MDR1/ABCB1 and MRP2/ABCC2 in patients with antiepileptic-drugs resistant epilepsy (ADR) is controversial. The aim of this study was to perform an exploratory study to identify nucleotide changes and search new and reported mutations in patients with ADR and patients with good response (CTR) to antiepileptic drugs (AEDs) in a rigorously selected population. We analyzed 22 samples In Material and Methods, from drug-resistant patients with epilepsy and 7 samples from patients with good response to AEDs. Genomic DNA was obtained from leukocytes. Eleven exons in both genes were genotyped. The concentration of drugs in saliva and plasma was determined. The concentration of valproic acid in saliva was lower in ADR than in CRT. In ABCB1, five reported SNPs and five unreported nucleotide changes were identified; rs2229109 (GA) and rs2032582 (AT and AG) were found only in the ADR. Of six SNPs associated with the ABCC2 that were found in the study population, rs3740066 (TT) and 66744T > A (TG) were found only in the ADR. The strongest risk factor in the ABCB1 gene was identified as the TA genotype of rs2032582, whereas for the ABCC2 gene the strongest risk factor was the T allele of rs3740066. The screening of SNPs in ACBC1 and ABCC2 indicates that the Mexican patients with epilepsy in this study display frequently reported ABCC1 polymorphisms; however, in the study subjects with a higher risk factor for drug resistance, new nucleotide changes were found in the ABCC2 gene. Thus, the population of Mexican patients with AED-resistant epilepsy (ADR) used in this study exhibits genetic variability with respect to those reported in other study populations; however, it is necessary to explore this polymorphism in a larger population of patients with ADR. PMID:25346718

  14. Association between the MDR1 gene variant C3435T and risk of leukaemia: a meta-analysis.

    PubMed

    Zhang, B-B; Xuan, C; Deng, K-F; Wu, N; Lun, L-M

    2013-09-01

    Although a number of genetic studies have attempted to link the multidrug resistance (MDR1) C3435T polymorphism to risk of leukaemia, the results were often inconsistent. The present study aimed at investigating the pooled association using a meta-analysis on the published studies. 1933 cases and 2215 controls of 11 published studies in English before June 2012 were involved in the updated meta-analysis. Furthermore, subgroup analysis was performed in different ethnic and leukaemia subtype groups. This meta-analysis suggests that the MDR1 C3435T polymorphism associate with risk of leukaemia. The effect of the variant on the expression levels and the possible functional role of the variant in leukaemia should be addressed in further studies.

  15. Quinone derivatives isolated from the endolichenic fungus Phialocephala fortinii are Mdr1 modulators that combat azole resistance in Candida albicans

    PubMed Central

    Xie, Fei; Chang, Wenqiang; Zhang, Ming; Li, Ying; Li, Wei; Shi, Hongzhuo; Zheng, Sha; Lou, Hongxiang

    2016-01-01

    One of the main azole-resistance mechanisms in Candida pathogens is the upregulation of drug efflux pumps, which compromises the efficacy of azoles and results in treatment failure. The combination of azole-antifungal agents with efflux pump inhibitors represents a promising strategy to combat fungal infection. High-throughput screening of 150 extracts obtained from endolichenic fungal cultures led to the discovery that the extract of Phialocephala fortinii exhibits potent activity for the reversal of azole resistance. From P. fortinii cultures, a total of 15 quinone derivatives, comprising 11 new derivatives and 4 known compounds, were obtained. Among these compounds, palmarumycin P3 (3) and phialocephalarin B (8) specifically modulate the expression of MDR1 to inhibit the activity of drug efflux pumps and therefore reverse azole resistance. The present study revealed Mdr1 targeting as an alternative mechanism for the discovery of new agents to fight antifungal drug resistance. PMID:27650180

  16. Quinone derivatives isolated from the endolichenic fungus Phialocephala fortinii are Mdr1 modulators that combat azole resistance in Candida albicans.

    PubMed

    Xie, Fei; Chang, Wenqiang; Zhang, Ming; Li, Ying; Li, Wei; Shi, Hongzhuo; Zheng, Sha; Lou, Hongxiang

    2016-01-01

    One of the main azole-resistance mechanisms in Candida pathogens is the upregulation of drug efflux pumps, which compromises the efficacy of azoles and results in treatment failure. The combination of azole-antifungal agents with efflux pump inhibitors represents a promising strategy to combat fungal infection. High-throughput screening of 150 extracts obtained from endolichenic fungal cultures led to the discovery that the extract of Phialocephala fortinii exhibits potent activity for the reversal of azole resistance. From P. fortinii cultures, a total of 15 quinone derivatives, comprising 11 new derivatives and 4 known compounds, were obtained. Among these compounds, palmarumycin P3 (3) and phialocephalarin B (8) specifically modulate the expression of MDR1 to inhibit the activity of drug efflux pumps and therefore reverse azole resistance. The present study revealed Mdr1 targeting as an alternative mechanism for the discovery of new agents to fight antifungal drug resistance. PMID:27650180

  17. Preferential cytotoxicity of bortezomib toward highly malignant human liposarcoma cells via suppression of MDR1 expression and function

    SciTech Connect

    Hu, Yamei; Wang, Lingxian; Wang, Lu; Wu, Xuefeng; Wu, Xudong; Gu, Yanhong; Shu, Yongqian; Sun, Yang; Shen, Yan; Xu, Qiang

    2015-02-15

    Liposarcoma is the most common soft tissue sarcoma with a high risk of relapse. Few therapeutic options are available for the aggressive local or metastatic disease. Here, we report that the clinically used proteasome inhibitor bortezomib exhibits significantly stronger cytotoxicity toward highly malignant human liposarcoma SW872-S cells compared with its parental SW872 cells, which is accompanied by enhanced activation of apoptotic signaling both in vitro and in vivo. Treatment of cells with Jun-N-terminal kinase (JNK) inhibitor SP60015 or the translation inhibitor cycloheximide ameliorated this enhanced apoptosis. Bortezomib inhibited MDR1 expression and function more effectively in SW872-S cells than in SW872 cells, indicating that the increased cytotoxicity relies on the degree of proteasome inhibition. Furthermore, the pharmacological or genetic inhibition of sarco/endoplasmic reticulum calcium-ATPase (SERCA) 2, which is highly expressed in SW872-S cells, resulted in partial reversal of cell growth inhibition and increase of MDR1 expression in bortezomib-treated SW872-S cells. These results show that bortezomib exhibits preferential cytotoxicity toward SW872-S cells possibly via highly expressed SERCA2-associated MDR1 suppression and suggest that bortezomib may serve as a potent agent for treating advanced liposarcoma. - Highlights: • We compare the cytotoxicity of different drugs between SW872-S and SW872 cells. • Highly malignant liposarcoma cells SW872-S show hypersensitivity to bortezomib. • Apoptotic signaling is robustly enhanced in bortezomib-treated SW872-S cells. • Bortezomib has strong suppression on MDR1 expression and function in SW872-S cells. • Inhibition of SERCA2 protects SW872-S cells from bortezomib.

  18. Downregulation of mdr1 and abcg2 genes is a mechanism of inhibition of efflux pumps mediated by polymeric amphiphiles.

    PubMed

    Cuestas, María L; Castillo, Amalia I; Sosnik, Alejandro; Mathet, Verónica L

    2012-11-01

    The ability of cells to acquire resistance to multiple pharmaceuticals, namely multidrug resistance (MDR), is often mediated by the over-expression of efflux transporters of the ATP-binding cassette (ABC) superfamily; for example P-glycoprotein (P-gp or MDR1), breast cancer resistance protein (BCRP or ABCG2), and multidrug resistance-associated protein MRP1. ABCs pump drug molecules out of cells against a concentration gradient, reducing their intracellular concentration. The ability of polymeric amphiphiles to inhibit ABCs as well as the cellular pathways involved in the inhibition has been extensively investigated. This work investigated for the first time the effect of branched poly(ethylene oxide)-poly(propylene oxide) block copolymers (poloxamines) on the levels of mRNA encoding for MDR1, BCRP and MRP1, in a human hepatoma cell line (Huh7). Copolymers with a broad range of molecular weights and hydrophilic-lipophilic balances were assayed. Results confirmed the down-regulation of mdr1 and abcg2 genes. Conversely, the mrp1 gene was not affected. These findings further support the versatility of these temperature- and pH-responsive copolymers to overcome drug resistance in cancer and infectious diseases.

  19. Pharmacokinetic simulations to explore dissolution criteria of BCS I and III biowaivers with and without MDR-1 efflux transporter.

    PubMed

    Kortejärvi, H; Malkki, J; Shawahna, R; Scherrmann, J-M; Urtti, A; Yliperttula, M

    2014-09-30

    In this study, a pharmacokinetic simulation model was used to explore the dissolution acceptance criteria for BCS I and III biowaivers and to examine the risk of MDR-1 efflux transporter on bioequivalence of substrates. The compartmental absorption and transit (CAT) model with one- or two systemic compartments was used. The parameter values used in the simulations were based on the pharmacokinetics of existing 70 BCS I and III drugs. Based on the simulations BCS I drug products with Tmax of >0.9 h, both dissolution criteria "very rapid" and "rapid and similar" were acceptable. For rapidly absorbed and distributed BCS I drug products with Tmax of 0.6-0.9 h, the dissolution criterion "very rapid" is preferred. If Tmax is less than 0.6 h there is a risk of bioinequivalence for the BCS I drug products regardless of the dissolution criteria. Based on the simulations, all BCS III drug products were good biowaiver candidates with both dissolution criteria. Almost all the BCS III drug products (>89%) and many BCS I products (9-57%) showed risks of bioinequivalence, if an excipient in either product inhibits MDR1-efflux transport of the drug. To eliminate these risks excipients with prior use in bioequivalent products should be used for MDR-1 efflux substrates.

  20. Downregulation of mdr1 and abcg2 genes is a mechanism of inhibition of efflux pumps mediated by polymeric amphiphiles.

    PubMed

    Cuestas, María L; Castillo, Amalia I; Sosnik, Alejandro; Mathet, Verónica L

    2012-11-01

    The ability of cells to acquire resistance to multiple pharmaceuticals, namely multidrug resistance (MDR), is often mediated by the over-expression of efflux transporters of the ATP-binding cassette (ABC) superfamily; for example P-glycoprotein (P-gp or MDR1), breast cancer resistance protein (BCRP or ABCG2), and multidrug resistance-associated protein MRP1. ABCs pump drug molecules out of cells against a concentration gradient, reducing their intracellular concentration. The ability of polymeric amphiphiles to inhibit ABCs as well as the cellular pathways involved in the inhibition has been extensively investigated. This work investigated for the first time the effect of branched poly(ethylene oxide)-poly(propylene oxide) block copolymers (poloxamines) on the levels of mRNA encoding for MDR1, BCRP and MRP1, in a human hepatoma cell line (Huh7). Copolymers with a broad range of molecular weights and hydrophilic-lipophilic balances were assayed. Results confirmed the down-regulation of mdr1 and abcg2 genes. Conversely, the mrp1 gene was not affected. These findings further support the versatility of these temperature- and pH-responsive copolymers to overcome drug resistance in cancer and infectious diseases. PMID:23031592

  1. Ursolic acid sensitized colon cancer cells to chemotherapy under hypoxia by inhibiting MDR1 through HIF-1α*

    PubMed Central

    Shan, Jian-zhen; Xuan, Yan-yan; Zhang, Qi; Huang, Jian-jin

    2016-01-01

    Objective: To explore the efficacy of ursolic acid in sensitizing colon cancer cells to chemotherapy under hypoxia and its underlying mechanisms. Methods: Three colon cancer cell lines (RKO, LoVo, and SW480) were used as in vitro models. 5-Fluorouracil (5-FU) and oxaliplatin were used as chemotherapeutic drugs. Cell viability and apoptosis were tested to evaluate the sensitivity of colon cancer cells to chemotherapy. The transcription and expression levels of hypoxia-inducible factor-1α (HIF-1α), multidrug resistance gene 1 (MDR1), and vascular endothelial growth factors (VEGF) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and immunoblotting. Cycloheximide and MG132 were used to inhibit protein synthesis and degradation, respectively. In vitro tube formation assay was used to evaluate angiogenesis. Results: We demonstrated the chemosensitizing effects of ursolic acid with 5-FU and oxaliplatin in three colon cancer cell lines under hypoxia. This effect was correlated to its inhibition of MDR1 through HIF-1α. Moreover, ursolic acid was capable of inhibiting HIF-1α accumulation with little effects on its constitutional expression in normoxia. In addition, ursolic acid also down-regulated VEGF and inhibited tumor angiogenesis. Conclusions: Ursolic acid exerted chemosensitizing effects in colon cancer cells under hypoxia by inhibiting HIF-1α accumulation and the subsequent expression of the MDR1 and VEGF. PMID:27604859

  2. Globally prevalent PfMDR1 mutations modulate Plasmodium falciparum susceptibility to artemisinin-based combination therapies.

    PubMed

    Veiga, M Isabel; Dhingra, Satish K; Henrich, Philipp P; Straimer, Judith; Gnädig, Nina; Uhlemann, Anne-Catrin; Martin, Rowena E; Lehane, Adele M; Fidock, David A

    2016-01-01

    Antimalarial chemotherapy, globally reliant on artemisinin-based combination therapies (ACTs), is threatened by the spread of drug resistance in Plasmodium falciparum parasites. Here we use zinc-finger nucleases to genetically modify the multidrug resistance-1 transporter PfMDR1 at amino acids 86 and 184, and demonstrate that the widely prevalent N86Y mutation augments resistance to the ACT partner drug amodiaquine and the former first-line agent chloroquine. In contrast, N86Y increases parasite susceptibility to the partner drugs lumefantrine and mefloquine, and the active artemisinin metabolite dihydroartemisinin. The PfMDR1 N86 plus Y184F isoform moderately reduces piperaquine potency in strains expressing an Asian/African variant of the chloroquine resistance transporter PfCRT. Mutations in both digestive vacuole-resident transporters are thought to differentially regulate ACT drug interactions with host haem, a product of parasite-mediated haemoglobin degradation. Global mapping of these mutations illustrates where the different ACTs could be selectively deployed to optimize treatment based on regional differences in PfMDR1 haplotypes. PMID:27189525

  3. Globally prevalent PfMDR1 mutations modulate Plasmodium falciparum susceptibility to artemisinin-based combination therapies

    PubMed Central

    Veiga, M. Isabel; Dhingra, Satish K.; Henrich, Philipp P.; Straimer, Judith; Gnädig, Nina; Uhlemann, Anne-Catrin; Martin, Rowena E.; Lehane, Adele M.; Fidock, David A.

    2016-01-01

    Antimalarial chemotherapy, globally reliant on artemisinin-based combination therapies (ACTs), is threatened by the spread of drug resistance in Plasmodium falciparum parasites. Here we use zinc-finger nucleases to genetically modify the multidrug resistance-1 transporter PfMDR1 at amino acids 86 and 184, and demonstrate that the widely prevalent N86Y mutation augments resistance to the ACT partner drug amodiaquine and the former first-line agent chloroquine. In contrast, N86Y increases parasite susceptibility to the partner drugs lumefantrine and mefloquine, and the active artemisinin metabolite dihydroartemisinin. The PfMDR1 N86 plus Y184F isoform moderately reduces piperaquine potency in strains expressing an Asian/African variant of the chloroquine resistance transporter PfCRT. Mutations in both digestive vacuole-resident transporters are thought to differentially regulate ACT drug interactions with host haem, a product of parasite-mediated haemoglobin degradation. Global mapping of these mutations illustrates where the different ACTs could be selectively deployed to optimize treatment based on regional differences in PfMDR1 haplotypes. PMID:27189525

  4. P-glycoprotein (MDR1/ABCB1) and breast cancer resistance protein (BCRP/ABCG2) restrict brain accumulation of the JAK1/2 inhibitor, CYT387.

    PubMed

    Durmus, S; Xu, N; Sparidans, R W; Wagenaar, E; Beijnen, J H; Schinkel, A H

    2013-10-01

    CYT387 is an orally bioavailable, small molecule inhibitor of Janus family of tyrosine kinases (JAK) 1 and 2. It is currently undergoing Phase I/II clinical trials for the treatment of myelofibrosis and myeloproliferative neoplasms. We aimed to establish whether the multidrug efflux transporters P-glycoprotein (P-gp; MDR1; ABCB1) and breast cancer resistance protein (BCRP;ABCG2) restrict oral availability and brain penetration of CYT387. In vitro, CYT387 was efficiently transported by both human MDR1 and BCRP, and very efficiently by mouse Bcrp1 and its transport could be inhibited by specific MDR1 inhibitor, zosuquidar and/or specific BCRP inhibitor, Ko143. CYT387 (10 mg/kg) was orally administered to wild-type (WT), Bcrp1(-/-), Mdr1a/1b(-/-) and Bcrp1;Mdr1a/1b(-/-) mice and plasma and brain concentrations were analyzed. Over 8h, systemic exposure of CYT387 was similar between all the strains, indicating that these transporters do not substantially limit oral availability of CYT387. Despite the similar systemic exposure, brain accumulation of CYT387 was increased 10.5- and 56-fold in the Bcrp1;Mdr1a/1b(-/-) mice compared to the WT strain at 2 and 8h after CYT387 administration, respectively. In single Bcrp1(-/-) mice, brain accumulation of CYT387 was more substantially increased than in Mdr1a/1b(-/-) mice, suggesting that CYT387 is a slightly better substrate of Bcrp1 than of Mdr1a at the blood-brain barrier. These results indicate a marked and additive role of Bcrp1 and Mdr1a/1b in restricting brain penetration of CYT387, potentially limiting efficacy of this compound against brain (micro) metastases positioned behind a functional blood-brain barrier.

  5. CD30 downregulation, MMAE resistance, and MDR1 upregulation are all associated with resistance to brentuximab vedotin

    PubMed Central

    Chen, Robert; Hou, Jessie; Newman, Edward; Kim, Young; Donohue, Cecile; Liu, Xueli; Thomas, Sandra H.; Forman, Stephen J.; Kane, Susan E.

    2015-01-01

    Brentuximab vedotin (BV) is an antibody-drug conjugate that specifically delivers the potent cytotoxic drug MMAE to CD30-positive cells. BV is FDA-approved for treatment of relapsed/refractory Hodgkin lymphoma (HL) and anaplastic large cell lymphoma (ALCL); however, many patients do not achieve complete remission and develop BV resistant disease. We selected for BV-resistant HL (L428) and ALCL (Karpas-299) cell lines using either constant (ALCL) or pulsatile (HL) exposure to BV. We confirmed drug resistance by MTS assay, and analyzed CD30 expression in resistant cells by flow cytometry, qRT-PCR, and Western blotting. We also measured drug exporter expression, MMAE resistance, and intracellular MMAE concentrations in BV-resistant cells. Additionally, tissue biopsy samples from 10 HL and 5 ALCL patients who had relapsed or progressed after BV treatment were analyzed by immunohistocytochemistry for CD30 expression. The resistant ALCL cell line, but not the HL cell line, demonstrated downregulated CD30 expression compared to the parental cell line. In contrast, the HL cell line, but not the ALCL cell line, exhibited MMAE resistance and increased expression of the MDR1 drug exporter compared to the parental line. For both HL and ALCL, samples from patients relapsed/resistant on BV persistently expressed CD30 by immunohistocytochemistry. One HL patient sample expressed MDR1 by immunohistocytochemistry. Although loss of CD30 expression is a possible mode of BV resistance in ALCL in vitro models, this has not been confirmed in patients. MMAE resistance and MDR1 expression are possible modes of BV resistance for HL both in vitro and in patients. PMID:25840583

  6. Genomic Profiling Reveals the Potential Role of TCL1A and MDR1 Deficiency in Chemotherapy-Induced Cardiotoxicity

    PubMed Central

    McCaffrey, Timothy A.; Tziros, Constantine; Lewis, Jannet; Katz, Richard; Siegel, Robert; Weglicki, William; Kramer, Jay; Mak, I. Tong; Toma, Ian; Chen, Liang; Benas, Elizabeth; Lowitt, Alexander; Rao, Shruti; Witkin, Linda; Lian, Yi; Lai, Yinglei; Yang, Zhaoqing; Fu, Sidney W.

    2013-01-01

    Background: Anthracyclines, such as doxorubicin (Adriamycin), are highly effective chemotherapeutic agents, but are well known to cause myocardial dysfunction and life-threatening congestive heart failure (CHF) in some patients. Methods: To generate new hypotheses about its etiology, genome-wide transcript analysis was performed on whole blood RNA from women that received doxorubicin-based chemotherapy and either did, or did not develop CHF, as defined by ejection fractions (EF)≤40%. Women with non-ischemic cardiomyopathy unrelated to chemotherapy were compared to breast cancer patients prior to chemo with normal EF to identify heart failure-related transcripts in women not receiving chemotherapy. Byproducts of oxidative stress in plasma were measured in a subset of patients. Results: The results indicate that patients treated with doxorubicin showed sustained elevations in oxidative byproducts in plasma. At the RNA level, women who exhibited low EFs after chemotherapy had 260 transcripts that differed >2-fold (p<0.05) compared to women who received chemo but maintained normal EFs. Most of these transcripts (201) were not altered in non-chemotherapy patients with low EFs. Pathway analysis of the differentially expressed genes indicated enrichment in apoptosis-related transcripts. Notably, women with chemo-induced low EFs had a 4.8-fold decrease in T-cell leukemia/lymphoma 1A (TCL1A) transcripts. TCL1A is expressed in both cardiac and skeletal muscle, and is a known co-activator for AKT, one of the major pro-survival factors for cardiomyocytes. Further, women who developed low EFs had a 2-fold lower level of ABCB1 transcript, encoding the multidrug resistance protein 1 (MDR1), which is an efflux pump for doxorubicin, potentially leading to higher cardiac levels of drug. In vitro studies confirmed that inhibition of MDR1 by verapamil in rat H9C2 cardiomyocytes increased their susceptibility to doxorubicin-induced toxicity. Conclusions: It is proposed that chemo

  7. Reversal of multidrug resistance in breast cancer MCF-7/ADR cells by h-R3-siMDR1-PAMAM complexes.

    PubMed

    Li, Jun; Liu, Jing; Guo, Nana; Zhang, Xiaoning

    2016-09-10

    Multidrug resistance (MDR) among breast cancer cells is the paramount obstacle for the successful chemotherapy. In this study, anti-EGFR antibody h-R3 was designed to self-assembled h-R3-siRNA-PAMAM-complexes (HSPCs) via electrostatic interactions for siRNA delivery. The physicochemical characterization, cell uptake, MDR1 silencing efficiency, cell migration, cell growth and cell apoptosis were investigated. The HSPCs presented lower cytotoxicity, higher cellular uptake and enhanced endosomal escape ability. Also, HSPCs encapsulating siMDR1 knockdowned 99.4% MDR1 gene with up to ∼6 times of enhancement compared to naked siMDR1, increased the doxorubicin accumulation, down-regulated P-glycoprotein (P-gp) expression and suppressed cellular migration in breast cancer MCF-7/ADR cells. Moreover, the combination of anticancer drug paclitaxel (PTX) and siMDR1 loaded HSPCs showed synergistic effect on overcoming MDR, which inhibited cell growth and induced cell apoptosis. This h-R3-mediated siMDR1 delivery system could be a promising vector for effective siRNA therapy of drug resistant breast cancer. PMID:27444552

  8. Identification of trichlormethiazide as a Mdr1a/b gene expression enhancer via a dual secretion-based promoter assay.

    PubMed

    Schulze, Sarina; Reinhardt, Sven; Freese, Christian; Schmitt, Ulrich; Endres, Kristina

    2015-02-01

    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.

  9. Genetic variation in MDR1, LPL and eNOS genes and the response to atorvastatin treatment in ischemic stroke.

    PubMed

    Munshi, Anjana

    2012-11-01

    Statins reduce the risk of cardiovascular events by lowering the blood cholesterol. Many genes involved in the pharmacodynamic pathway of statins have been part of pharmacogenetic research in patients with hypercholesterolemia, with an emphasis on genes involved in the cholesterol pathway. The present study was carried out with an aim to evaluate the association between the genetic variants of lipoprotein lipase gene [HindIII (+/+)/HindIII (-/-)], multiple drug resistance gene (C3435T) and endothelial nitric oxide synthase gene (4a/4b) with clinical outcome including an increased risk of recurrent stroke or death in ischemic stroke patients on atorvastatin therapy. 525 stroke patients and 500 healthy controls were involved in the study. Follow-up telephone interviews were conducted with patients post-event to determine stroke outcome. Blood samples were collected and genotypes determined by polymerase chain reaction-restriction digestion technique. A significant association of MDR1 and LPL gene variants with bad outcome in stroke patients on atorvastatin therapy was found. However, there was no significant association of 27 bp VNTR polymorphism of eNOS gene with outcome. MDR analysis was carried out to analyze gene-gene interaction involving these gene variants contributing to clinical outcome of patients on stratin therapy but no significant interaction between these variants was observed. In conclusion the individuals with HindIII (-/-) genotype of LPL and CC genotype of MDR1 gene would benefit more from atorvastatin therapy. PMID:22810051

  10. Homogeneously staining region in anthracycline-resistant HL-60/AR cells not associated with MDR1 amplification.

    PubMed

    Gervasoni, J E; Taub, R N; Yu, M T; Warburton, D; Sabbath, M; Gilleran, S; Coppock, D L; D'Alessandri, J; Krishna, S; Rosado, M

    1992-10-01

    Anthracycline-resistant HL-60/AR cells and their drug-sensitive HL-60/S counterparts were characterized by karyotypic analysis and examined for the overexpression of DNA and mRNA sequences coding for P-glycoprotein (Pgp). The HL-60/S cells were karyotypically stable over a 5-year period of study (1986-1991), except for an additional small Giemsa-positive band noted at 7q22 in cultures harvested in 1987, but not in 1986. This change did not affect drug sensitivity. The drug-resistant HL-60/AR cells examined in 1986, 1987, and 1991 demonstrated a very stable karyotype. The most striking feature was a large homogeneously staining region in the long arm of chromosome 7 (7q11.2), and translocation of the remainder of the long arm to another centromere. Other changes in the HL-60/AR cells included inversion in 9q, partial deletion of the short arm of chromosome 10p, addition of material to the p arm of der(16), loss of chromosome 22, and the appearance of a new marker chromosome. Both HL-60/S and the HL-60/AR cells were found not to amplify DNA or mRNA sequences coding for the Pgp. Thus, although the HL-60/AR cells possess the classical multidrug resistance phenotype and demonstrate a homogeneously staining region near the region of the MDR1 gene, their resistance is due to mechanisms other than those coded for by MDR1.

  11. PfCRT and PfMDR1 modulate interactions of artemisinin derivatives and ion channel blockers

    PubMed Central

    Eastman, Richard T.; Khine, Pwint; Huang, Ruili; Thomas, Craig J.; Su, Xin-zhuan

    2016-01-01

    Treatment of the symptomatic asexual stage of Plasmodium falciparum relies almost exclusively on artemisinin (ART) combination therapies (ACTs) in endemic regions. ACTs combine ART or its derivative with a long-acting partner drug to maximize efficacy during the typical three-day regimen. Both laboratory and clinical studies have previously demonstrated that the common drug resistance determinants P. falciparum chloroquine resistance transporter (PfCRT) and multidrug resistance transporter (PfMDR1) can modulate the susceptibility to many current antimalarial drugs and chemical compounds. Here we investigated the parasite responses to dihydroartemisinin (DHA) and various Ca2+ and Na+ channel blockers and showed positively correlated responses between DHA and several channel blockers, suggesting potential shared transport pathways or mode of action. Additionally, we demonstrated that PfCRT and PfMDR1 could also significantly modulate the pharmacodynamic interactions of the compounds and that the interactions were influenced by the parasite genetic backgrounds. These results provide important information for better understanding of drug resistance and for assessing the overall impact of drug resistance markers on parasite response to ACTs. PMID:27147113

  12. Inhibition of ABCB1 (MDR1) Expression by an siRNA Nanoparticulate Delivery System to Overcome Drug Resistance in Osteosarcoma

    PubMed Central

    Ryu, Keinosuke; Choy, Edwin; Hornicek, Francis J.; Mankin, Henry; Milane, Lara; Amiji, Mansoor M.; Duan, Zhenfeng

    2010-01-01

    Background The use of neo-adjuvant chemotherapy in treating osteosarcoma has improved patients' average 5 year survival rate from 20% to 70% in the past 30 years. However, for patients who progress after chemotherapy, its effectiveness diminishes due to the emergence of multi-drug resistance (MDR) after prolonged therapy. Methodology/Principal Findings In order to overcome both the dose-limiting side effects of conventional chemotherapeutic agents and the therapeutic failure resulting from MDR, we designed and evaluated a novel drug delivery system for MDR1 siRNA delivery. Novel biocompatible, lipid-modified dextran-based polymeric nanoparticles were used as the platform for MDR1 siRNA delivery; and the efficacy of combination therapy with this system was evaluated. In this study, multi-drug resistant osteosarcoma cell lines (KHOSR2 and U-2OSR2) were treated with the MDR1 siRNA nanocarriers and MDR1 protein (P-gp) expression, drug retention, and immunofluoresence were analyzed. Combination therapy of the MDR1 siRNA loaded nanocarriers with increasing concentrations of doxorubicin was also analyzed. We observed that MDR1 siRNA loaded dextran nanoparticles efficiently suppresses P-gp expression in the drug resistant osteosarcoma cell lines. The results also demonstrated that this approach may be capable of reversing drug resistance by increasing the amount of drug accumulation in MDR cell lines. Conclusions/Significance Lipid-modified dextran-based polymeric nanoparticles are a promising platform for siRNA delivery. Nanocarriers loaded with MDR1 siRNA are a potential treatment strategy for reversing MDR in osteosarcoma. PMID:20520719

  13. The cytotoxic effect of unconjugated bilirubin in human neuroblastoma SH-SY5Y cells is modulated by the expression level of MRP1 but not MDR1.

    PubMed

    Corich, Lucia; Aranda, Alejandro; Carrassa, Laura; Bellarosa, Cristina; Ostrow, J Donald; Tiribelli, Claudio

    2009-01-01

    In vitro and in vivo studies have demonstrated that UCB (unconjugated bilirubin) is neurotoxic. Although previous studies suggested that both MRP1 (multidrug resistance-associated protein 1) and MDR1 (multidrug resistance protein 1) may protect cells against accumulation of UCB, direct comparison of their role in UCB transport was never performed. To this end, we used an inducible siRNA (small interfering RNA) expression system to silence the expression of MRP1 and MDR1 in human neuroblastoma SH-SY5Y cells. The effects of in vitro exposure to clinically-relevant levels of unbound UCB were compared between unsilenced (control) cells and cells with similar reductions in the expression of MRP1 or MDR1, documented by RT-PCR (reverse transcription-PCR) (mRNA), immunoblotting (protein), and for MDR1, the enhanced net uptake of a specific fluorescent substrate. Cytotoxicity was assessed by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] test. MRP1-deficient cells accumulated significantly more UCB and suffered greater cytotoxicity than controls. By contrast, MDR1-deficient cells exhibited UCB uptake and cytotoxicity comparable with controls. At intermediate levels of silencing, the increased susceptibility to UCB toxicity closely correlated with the decrease in the expression of MRP1, but not of MDR1. These data support the concept that limitation of cellular UCB accumulation, due to UCB export mediated by MRP1, but not MDR1, plays an important role in preventing bilirubin encephalopathy in the newborn.

  14. Optimized Ultrasound Conditions for Enhanced Sensitivity of Molecular Beacons in the Detection of MDR1 mRNA in Living Cells.

    PubMed

    Zhou, Qiumei; Ma, Yi; Wang, Zhaohui; Wang, Ke; Liu, Ruonan; Han, Zhihao; Zhang, Min; Li, Siwen; Gu, Yueqing

    2016-03-01

    P-glycoprotein (P-gp), aprognostic indicator for chemotherapy failure, is encoded by multidrug resistance gene (MDR1). MDR1 mRNA expression could serve as a guidance for personalized medicine. However, the traditional PCR process for mRNA measurement is complicated and cannot realize the real-time detection of mRNA in living single cells. In this work, optimized gold nanoparticle-based molecular beacons were employed to determine MDR1 mRNA levels in living cancer cells. To improve detection sensitivity, ultrasound (US) irradiation was applied to facilitate and enhance cellular uptake of hairpin DNA-coated gold nanoparticle (hDAuNP). The US conditions including irradiation power, exposure time, duty cycle, and incubation time were optimized. The slight difference in MDR1 expression manipulated by siRNA silence could be recognized by US assisted hDAuNP beacons; a 10-fold increase of detection sensitivity was achieved compared with the nonultrasound assistance. Meanwhile, the detection cycle could be shortened from 12 to 2 h. Furthermore, this hDAuNP beacon can serve as an antisense agent to down-regulate P-gp expression and to reverse drug resistance of MCF-7/Adr cells to doxorubicin. Our results demonstrated that the MDR1 hDAuNP beacon assisted by US irradiation had great potential to predict chemotherapy sensitivity and to overcome multidrug resistance in cancer cells and was thus a promising tool for individualized medicine.

  15. Optimized Ultrasound Conditions for Enhanced Sensitivity of Molecular Beacons in the Detection of MDR1 mRNA in Living Cells.

    PubMed

    Zhou, Qiumei; Ma, Yi; Wang, Zhaohui; Wang, Ke; Liu, Ruonan; Han, Zhihao; Zhang, Min; Li, Siwen; Gu, Yueqing

    2016-03-01

    P-glycoprotein (P-gp), aprognostic indicator for chemotherapy failure, is encoded by multidrug resistance gene (MDR1). MDR1 mRNA expression could serve as a guidance for personalized medicine. However, the traditional PCR process for mRNA measurement is complicated and cannot realize the real-time detection of mRNA in living single cells. In this work, optimized gold nanoparticle-based molecular beacons were employed to determine MDR1 mRNA levels in living cancer cells. To improve detection sensitivity, ultrasound (US) irradiation was applied to facilitate and enhance cellular uptake of hairpin DNA-coated gold nanoparticle (hDAuNP). The US conditions including irradiation power, exposure time, duty cycle, and incubation time were optimized. The slight difference in MDR1 expression manipulated by siRNA silence could be recognized by US assisted hDAuNP beacons; a 10-fold increase of detection sensitivity was achieved compared with the nonultrasound assistance. Meanwhile, the detection cycle could be shortened from 12 to 2 h. Furthermore, this hDAuNP beacon can serve as an antisense agent to down-regulate P-gp expression and to reverse drug resistance of MCF-7/Adr cells to doxorubicin. Our results demonstrated that the MDR1 hDAuNP beacon assisted by US irradiation had great potential to predict chemotherapy sensitivity and to overcome multidrug resistance in cancer cells and was thus a promising tool for individualized medicine. PMID:26821347

  16. P-Glycoprotein/MDR1 regulates pokemon gene transcription through p53 expression in human breast cancer cells.

    PubMed

    He, Shengnan; Liu, Feng; Xie, Zhenhua; Zu, Xuyu; Xu, Wei; Jiang, Yuyang

    2010-01-01

    P-glycoprotein (Pgp), encoded by the multidrug resistance 1 (MDR1) gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of p53 as seen by use of p53 siRNA transfected MCF-7 cells or p53 mutated MDA-MB-231 cells. Moreover, p53 was detected to bind with Pgp in vivo using immunoprecipitation assay. Taken together, we conclude that Pgp can regulate the expression of pokemon through the presence of p53, suggesting that Pgp is a potent regulator and may offer an effective novel target for cancer therapy. PMID:20957096

  17. P-Glycoprotein/MDR1 regulates pokemon gene transcription through p53 expression in human breast cancer cells.

    PubMed

    He, Shengnan; Liu, Feng; Xie, Zhenhua; Zu, Xuyu; Xu, Wei; Jiang, Yuyang

    2010-01-01

    P-glycoprotein (Pgp), encoded by the multidrug resistance 1 (MDR1) gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of p53 as seen by use of p53 siRNA transfected MCF-7 cells or p53 mutated MDA-MB-231 cells. Moreover, p53 was detected to bind with Pgp in vivo using immunoprecipitation assay. Taken together, we conclude that Pgp can regulate the expression of pokemon through the presence of p53, suggesting that Pgp is a potent regulator and may offer an effective novel target for cancer therapy.

  18. Comparative evaluation by semiquantitative reverse transcriptase polymerase chain reaction of MDR1, MRP and GSTp gene expression in breast carcinomas.

    PubMed Central

    Lacave, R.; Coulet, F.; Ricci, S.; Touboul, E.; Flahault, A.; Rateau, J. G.; Cesari, D.; Lefranc, J. P.; Bernaudin, J. F.

    1998-01-01

    Identification and quantitative evaluation of drug resistance markers are essential to assess the impact of multidrug resistance (MDR) in clinical oncology. The MDR1 gene confers pleiotropic drug resistance in tumour cells, but other molecular mechanisms are also involved in drug resistance. In particular, the clinical pattern of expression of the other MDR-related genes is unclear and their interrelationships are still unknown. Here, we report standardization of the procedures used to determine a reliable method of semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) using a standard series of drug-sensitive and increasingly resistant cell lines to evaluate the expression of three MDR-related genes, i.e. MDR1 (multidrug resistance gene 1), MRP (multidrug resistance related protein) and GSTp (glutathione-S-transferase p), reported to be endogenous standard genes for normalization of mRNAs. A total of 74 breast cancer surgical biopsies, obtained before any treatment, were evaluated by this method. When compared with classical clinical and laboratory findings, GSTp mRNA level was higher in diploid tumours. However, the main finding of our study suggests a clear relationship between two of these MDR-related gene expressions, namely GSTp and MRP. This finding provides new insight into human breast tumours, which may possibly be linked to the glutathione conjugate carrier function of MRP. Well defined semiquantitative RT-PCR procedures can therefore constitute a powerful tool to investigate MDR phenotype at mRNA levels of different related genes in small and precious tumour biopsy specimens. Images Figure 1 PMID:9514046

  19. The role of mdr1a P-glycoprotein in the biliary and intestinal secretion of doxorubicin and vinblastine in mice.

    PubMed

    van Asperen, J; van Tellingen, O; Beijnen, J H

    2000-03-01

    Drug-transporting P-glycoproteins are abundantly present in the liver and the intestinal wall. We have now investigated their role in the biliary and intestinal secretion of the anticancer drugs doxorubicin (unlabeled: 5 mg/kg) and vinblastine ((3)H-labeled: 1 mg/kg) i.v. administered to wild-type and mdr1a P-glycoprotein knockout [mdr1a(-/-)] mice. At 90 min after drug administration, levels of unchanged drug and metabolites in plasma, intestinal contents, and bile were determined by high-performance liquid chromatography and radioactivity by liquid scintillation counting. The bile of both wild-type and mdr1a(-/-) mice contained only minor amounts of unchanged vinblastine, whereas the total biliary secretion of unknown (3)H-labeled breakdown products was about 25 to 30% of the dose. The direct secretion of unchanged vinblastine through the gut wall was 6.7 and 3.3% of the dose in wild-type and mdr1a(-/-) mice, respectively. The biliary secretion of unchanged doxorubicin decreased from 13.3% of the dose to only 2.4% in the absence of mdr1a P-glycoprotein. Approximately 10% of the dose was secreted as unchanged doxorubicin into the intestinal contents of both types of mice. Thus, the absence of mdr1a P-glycoprotein affects the fate of vinblastine chiefly by diminishing secretion into the lumen of the small intestine, whereas it affects the fate of doxorubicin chiefly by diminishing secretion of parent drug into bile.

  20. pHluorin enables insights into the transport mechanism of antiporter Mdr1: R215 is critical for drug/H+ antiport.

    PubMed

    Redhu, Archana Kumari; Khandelwal, Nitesh Kumar; Banerjee, Atanu; Moreno, Alexis; Falson, Pierre; Prasad, Rajendra

    2016-10-01

    Multidrug resistance 1 (MDR1) is a member of the major facilitator superfamily that contributes to MDR of Candida albicans This antiporter belongs to the drug/H(+) antiporter 1 family, pairing the downhill gradient of protons to drug extrusion. Hence, drug efflux from cytosol to extracellular space and the parallel import of H(+) towards cytosol are inextricably linked processes. For monitoring the drug/H(+) antiporter activity of Mdr1p, we developed a new system, exploiting a GFP variant pHluorin, which changes its fluorescence properties with pH. This enabled us to measure the cytosolic pH correlated to drug efflux. Since protonation of charged residues is a key step in proton movement, we explored the role of all charged residues of the 12 transmembrane segments (TMSs) of Mdr1p in drug/H(+) transport by mutational analysis. This revealed that the conserved residue R(215), positioned close to the C-terminal end of TMS-4, is critical for drug/H(+) antiport, allowing protonation over a range of pH, in contrast with its H(215) or K(215) variants that failed to transport drugs at basic pH. Mutation of other residues of TMS-4 highlights the role of this TMS in drug transport, as confirmed by in silico modelling of Mdr1p and docking of drugs. The model points to the importance of R(215) in proton transport, suggesting that it may adopt two main conformations, one oriented towards the extracellular face and the other towards the centre of Mdr1p. Together, our results not only establish a new system for monitoring drug/H(+) transport, but also unveil a positively charged residue critical to Mdr1p function.

  1. The single nucleotide polymorphism and haplotype analysis of MDR1 in Chinese diffuse large B cell lymphoma patients.

    PubMed

    Ni, Ying; Xiao, Zhengrui; Yin, Guangli; Fan, Lei; Wang, Li; Zhu, Huayuan; Wu, Hanxin; Qian, Sixuan; Xu, Wei; Li, Jianyong; Miao, Kourong

    2015-07-01

    We investigated whether the MDR1 (multidrug resistance 1) gene single nucleotide polymorphism (SNP) and haplotype variants were associated with the susceptibility to diffuse large B-cell lymphoma (DLBCL). A total of 129 DLBCL patients and 208 healthy controls from Jiangsu Han population were enrolled in this study. They were genotyped by polymerase chain reaction-allele specific primers (PCR-ASP) method or DNA direct sequencing at three common loci: C1236T, G2677T/A and C3435T. At locus G2677T/A, allele G and genotype GT were significantly more common in DLBCL (G: OR=1.48, 95% CI: 1.08-2.02, Pc=0.03; GT: OR=1.96, 95% CI: 1.25-3.07, Pc<0.01), while genotype AT in this locus seemed to be protective (OR=0.29, 95% CI: 0.02-0.72, Pc=0.03). TT genotype at locus C3435T showed a risk factor in DLBCL (OR=2.38, 95% CI: 1.52-3.74, Pc<0.01). The frequency of T-G-T haplotype was significantly increased in DLBCL group (OR=5.21, 95% CI: 2.58-10.54, Pc<0.01); haplotype of G-T in 2677-3435 and diplotype of 2677GT/3435TT were significantly more frequent in DLBCL group (G-T: OR=3.97, 95% CI: 2.31-6.85, Pc<0.01; 2677GT/3435TT: OR=4.55, 95% CI: 2.02-10.22, Pc<0.01). Our findings demonstrate that G, GT at locus G2677T/A, and TT at locus C3435T might contribute to the susceptibility to DLBCL, as well as haplotype of T-G-T, G-T in 2677-3435 and diplotype of 2677GT/3435TT, while AT at locus G2677T/A might be a protective genotype. These findings could provide evidence that the MDR1 SNPs may modify the susceptibility to DLBCL and shade new lights in disease association studies.

  2. MDR1-P-glycoprotein behaves as an oncofetal protein that promotes cell survival in gastric cancer cells.

    PubMed

    Rocco, Alba; Compare, Debora; Liguori, Eleonora; Cianflone, Alessandra; Pirozzi, Giuseppe; Tirino, Virginia; Bertoni, Alessandra; Santoriello, Margherita; Garbi, Corrado; D'Armiento, Maria; Staibano, Stefania; Nardone, Gerardo

    2012-10-01

    P-glycoprotein (P-gp), traditionally linked to cancer poor prognosis and multidrug resistance, is undetectable in normal gastric mucosa and overexpressed in gastric cancer (GC). We propose that P-gp may be involved in Helicobacter pylori (Hp)-related gastric carcinogenesis by inhibiting apoptosis. Aim of the study was to evaluate the expression of P-gp in fetal stomach and in Hp-related gastric carcinogenesis, the epigenetic control of the multi-drug resistance-1 (MDR1) gene, the localization and interaction between P-gp and Bcl-x(L) and the effect of the selective silencing of P-gp on cell survival. P-gp and Bcl-xl expression was evaluated by immunohistochemistry on 28 spontaneously abortive human fetuses, 66 Hp-negative subjects, 138 Hp-positive chronic gastritis (CG) of whom 28 with intestinal metaplasia (IM) and 45 intestinal type GCs. P-gp/Bcl-x(L) colocalization was investigated by confocal immunofluorescence microscopy and protein-protein interaction by co-immunoprecipitation, in basal conditions and after stress-induced apoptosis, in GC cell lines AGS and MKN-28 and hepatocellular carcinoma cell line Hep-G2. The role of P-gp in controlling apoptosis was evaluated by knocking down its expression with a specific small interfering RNAs in stressed AGS and MKN-28 cell lines. P-gp is expressed in the gastric mucosa of all human fetuses while, it is undetectable in adult normal mucosa and re-expressed in 30/110 Hp-positive non-IM-CG, 28/28 IM-CG and 40/45 GCs. P-gp expression directly correlates with that of Bcl-x(L) and with the promoter hypomethylation of the MDR1 gene. In GC cell lines, P-gp is localized on the plasma membrane and mitochondria where it colocalizes with Bcl-x(L). Co-immunoprecipitation confirms the physical interaction between P-gp and Bcl-x(L) in AGS, MKN-28 and Hep-G2, at both basal level and after stress-induced apoptosis. The selective silencing of P-gp sensitizes GC cells to stress-induced apoptosis. P-gp behaves as an oncofetal protein

  3. Enhancement effect of resveratrol on the intestinal absorption of bestatin by regulating PEPT1, MDR1 and MRP2 in vivo and in vitro.

    PubMed

    Jia, Yongming; Liu, Zhihao; Huo, Xiaokui; Wang, Changyuan; Meng, Qiang; Liu, Qi; Sun, Huijun; Sun, Pengyuan; Yang, Xiaobo; Shu, Xiaohong; Liu, Kexin

    2015-11-10

    The purpose of present study was to assess the enhancing effect of resveratrol (Res) on the absorption of bestatin and clarify the related molecular mechanism. Res facilitated bestatin absorption by down-regulating both protein and gene levels of multidrug resistance 1 (Mdr1) and Multidrug resistance-associated protein 2 (Mrp2), and up-regulating oligopeptide transporter 1 (Pept1) protein and mRNA expression in rat intestine. In the same manner, Res increased penetration of bestatin via significantly activating mRNA and protein expression of PEPT1 in Caco-2 cells. Conversely, mRNA and protein expression levels of MDR1, MRP2 and phosphorylation level of Insulin-like growth factor 1 receptor (IGF-1R) were inhibited by Res in Caco-2 cells. Moreover, Res also altered the phosphorylation of extracellular signal-regulated kinase (ERK) and protein kinase B (AKT). Res enhanced the intracellular concentration of bestatin by down-regulating MDR1 and MRP2 expression through a mechanism that involves IGF-1R/AKT/ERK signaling pathway inhibition in Caco-2 cells. In conclusion, Res enhances bestatin absorption by regulating PEPT1, MDR1 and MRP2 both in vivo and in vitro.

  4. Expression of a full-length cDNA for the human MDR1 gene confers resistance to colchicine, doxorubicin, and vinblastine

    SciTech Connect

    Ueda, K.; Cardarelli, C.; Gottesman, M.M.; Pastan, I.

    1987-05-01

    Intrinsic and acquired multidrug resistance (MDR) is an important problem in cancer therapy. MDR in human KB carcinoma cells selected for resistance to colchicine, vinblastine, or doxorubicin (former generic name adriamycin) is associated with overexpression of the MDR1 gene, which encodes P-glycoprotein. The authors previously have isolated an overlapping set of cDNA clones for the human MDR1 gene from multidrug-resistant KB cells. Here they report the construction of a full-length cDNA for the human MDR1 gene and show that this reconstructed cDNA, when inserted into a retroviral expression vector containing the long terminal repeats of Moloney leukemia virus or Harvey sarcoma virus, functions in mouse NIH 3T3 and human KB cells to confer the complete multidrug-resistance phenotype. These results suggest that the human MDR1 gene may be used as a positive selectable marker to introduce genes into human cells and to transform human cells to multidrug resistance without introducing nonhuman antigens.

  5. Fluconazole transport into Candida albicans secretory vesicles by the membrane proteins Cdr1p, Cdr2p, and Mdr1p.

    PubMed

    Basso, Luiz R; Gast, Charles E; Mao, Yuxin; Wong, Brian

    2010-06-01

    A major cause of azole resistance in Candida albicans is overexpression of CDR1, CDR2, and/or MDR1, which encode plasma membrane efflux pumps. To analyze the catalytic properties of these pumps, we used ACT1- and GAL1-regulated expression plasmids to overexpress CDR1, CDR2, or MDR1 in a C. albicans cdr1 cdr2 mdr1-null mutant. When the genes of interest were expressed, the resulting transformants were more resistant to multiple azole antifungals, and accumulated less [(3)H]fluconazole intracellularly, than empty-vector controls. Next, we used a GAL1-regulated dominant negative sec4 allele to cause cytoplasmic accumulation of post-Golgi secretory vesicles (PGVs), and we found that PGVs isolated from CDR1-, CDR2-, or MDR1-overexpressing cells accumulated much more [(3)H]fluconazole than did PGVs from empty-vector controls. The K(m)s (expressed in micromolar concentrations) and V(max)s (expressed in picomoles per milligram of protein per minute), respectively, for [(3)H]fluconazole transport were 0.8 and 0.91 for Cdr1p, 4.3 and 0.52 for Cdr2p, and 3.5 and 0.59 for Mdr1p. [(3)H]fluconazole transport by Cdr1p and Cdr2p required ATP and was unaffected by carbonyl cyanide 3-chlorophenylhydrazone (CCCP), whereas [(3)H]fluconazole transport by Mdr1p did not require ATP and was inhibited by CCCP. [(3)H]fluconazole uptake by all 3 pumps was inhibited by all other azoles tested, with 50% inhibitory concentrations (IC(50)s; expressed as proportions of the [(3)H]fluconazole concentration) of 0.2 to 5.6 for Cdr1p, 0.3 to 3.1 for Cdr2p, and 0.3 to 3.1 for Mdr1p. The methods used in this study may also be useful for studying other plasma membrane transporters in C. albicans and other medically important fungi.

  6. Genetic Polymorphisms of Multidrug Resistance Gene-1 (MDR1/ABCB1) and Glutathione S-Transferase Gene and the Risk of Inflammatory Bowel Disease among Moroccan Patients

    PubMed Central

    Senhaji, Nezha; Kassogue, Yaya; Fahimi, Mina; Serbati, Nadia; Badre, Wafaa; Nadifi, Sellama

    2015-01-01

    Inflammatory bowel diseases (IBD) are multifactorial disorders resulting from environmental and genetic factors. Polymorphisms in MDR1 and GSTs genes might explain individual differences in susceptibility to IBD. We carried out a case-control study to examine the association of MDR1 (C1236T and C3435T), GSTT1, and GSTM1 polymorphisms with the risk of IBD. Subjects were genotyped using PCR-RFLP for MDR1 gene and multiplex PCR for GSTT1 and GSTM1. Meta-analysis was performed to test the association of variant allele carriage with IBD risk. We report that GSTT1 null genotype is significantly associated with the risk of CD (OR: 2.5, CI: 1.2–5, P = 0.013) and UC (OR: 3.5, CI: 1.5–8.5, P = 0.004) and can influence Crohn's disease behavior. The interaction between GSTT1 and GSTM1 genes showed that the combined null genotypes were associated with the risk of UC (OR: 3.1, CI: 1.1–9, P = 0.049). Furthermore, when compared to combined 1236CC/CT genotypes, the 1236TT genotype of MDR1 gene was associated with the risk of UC (OR: 3.7, CI: 1.3–10.7, P = 0.03). Meta-analysis demonstrated significantly higher frequencies of 3435T carriage in IBD patients. Our results show that GSTT1 null and MDR1 polymorphisms could play a role in susceptibility to IBD. PMID:26604430

  7. Fumonisin toxicity in a transgenic mouse model lacking the mdr1a/1b P-glycoprotein genes.

    PubMed

    Sharma; Bhandari; Tsunoda; Riley; Voss; Meredith

    2000-03-01

    The toxicity of fumonisin B(1) (FB(1)) was investigated in male mdr1a/1b double knockout (MDRK) mice, lacking the drug-transporting P-glycoproteins. These transgenic animals are deficient in their blood:brain barrier and accumulate different drugs in brain and other tissues. The MDRK and their wild-type counterparts, FVB mice, were injected subcutaneously with 2.25 mg/kg per day of FB(1) for 5 days and sampled one day after the last treatment in a protocol that has resulted in marked hepatic and renal damage in other strains. FB(1) caused liver enlargement in both FVB and MDRK. Hematological parameters were not affected in either strain. Plasma levels of alanine aminotransferase and aspartate aminotransferase, measures of liver damage, were increased by FB(1) in both FVB and MDRK mice. Histopathological evaluation of liver corroborated this finding. Kidney lesions were induced by FB(1) in both types of mice. Concentrations of free sphingosine and sphinganine increased in liver and kidney of both strains after the FB(1) treatment, although the increase in liver sphingoid bases was half as much in MDRK as compared to FVB. The levels of sphinganine-containing complex sphingolipids were increased in kidney. The levels of sphingosine-containing complex sphingolipids in kidney were unaffected by FB(1) treatment but were significantly lower in control MDRK than in FVB mice. The levels of neurotransmitters and their metabolites were similarly affected in both strains by FB(1), suggesting no influence of disrupted blood:brain barrier on FB(1)-induced neurotoxicity. In both strains, the liver mRNA for tumor necrosis factor alpha was increased; however, the increase was statistically significant only in FVB. It was apparent that mice deficient in P-glycoprotein do not exhibit greater sensitivity to FB(1), the cellular or brain transport of FB(1) appears to be independent of this multidrug transporting system.

  8. Analysis of the mdr-1 gene in patients co-infected with Onchocerca volvulus and Loa loa who experienced a post-ivermectin serious adverse event.

    PubMed

    Bourguinat, Catherine; Kamgno, Joseph; Boussinesq, Michel; Mackenzie, Charles D; Prichard, Roger K; Geary, Timothy G

    2010-07-01

    Ivermectin (IVM) is exceptionally safe in humans, and is used for mass treatment of onchocerciasis and lymphatic filariasis. However, cases of encephalopathy, sometimes fatal, have been reported in a small number of individuals who harbored large numbers of Loa loa microfilariae (mf). A loss-of-function mutation in the mdr-1 gene in some dog breeds and in mice leads to accumulation of the drug in the brain, causing coma and death. This hypothesis was tested in four individuals from Cameroon who experienced a post-IVM serious adverse event (SAE) and in nine non-SAE matched controls. No loss-of-function mutation was detected in mdr-1 in any subject. However, haplotypes, associated with altered drug disposition, were present as homozygotes in two of the SAE patients (50%), but absent as homozygotes in the controls (0%). An association of high Loa mf load and a genetic predisposition to altered IVM distribution could be involved in IVM SAEs. PMID:20595473

  9. UV-triggered Affinity Capture Identifies Interactions between the Plasmodium falciparum Multidrug Resistance Protein 1 (PfMDR1) and Antimalarial Agents in Live Parasitized Cells*

    PubMed Central

    Brunner, Ralf; Ng, Caroline L.; Aissaoui, Hamed; Akabas, Myles H.; Boss, Christoph; Brun, Reto; Callaghan, Paul S.; Corminboeuf, Olivier; Fidock, David A.; Frame, Ithiel J.; Heidmann, Bibia; Le Bihan, Amélie; Jenö, Paul; Mattheis, Corinna; Moes, Suzette; Müller, Ingrid B.; Paguio, Michelle; Roepe, Paul D.; Siegrist, Romain; Voss, Till; Welford, Richard W. D.; Wittlin, Sergio; Binkert, Christoph

    2013-01-01

    A representative of a new class of potent antimalarials with an unknown mode of action was recently described. To identify the molecular target of this class of antimalarials, we employed a photo-reactive affinity capture method to find parasite proteins specifically interacting with the capture compound in living parasitized cells. The capture reagent retained the antimalarial properties of the parent molecule (ACT-213615) and accumulated within parasites. We identified several proteins interacting with the capture compound and established a functional interaction between ACT-213615 and PfMDR1. We surmise that PfMDR1 may play a role in the antimalarial activity of the piperazine-containing compound ACT-213615. PMID:23754276

  10. Inhibitory effects of neochamaejasmin B on P-glycoprotein in MDCK-hMDR1 cells and molecular docking of NCB binding in P-glycoprotein.

    PubMed

    Pan, Lanying; Hu, Haihong; Wang, Xiangjun; Yu, Lushan; Jiang, Huidi; Chen, Jianzhong; Lou, Yan; Zeng, Su

    2015-01-01

    Stellera chamaejasme L. (Thymelaeaceae) is widely distributed in Mongolia, Tibet and the northern parts of China. Its roots are commonly used as "Langdu", which is embodied in the Pharmacopoeia of the P.R. China (2010) as a toxic Traditional Chinese Medicine. It is claimed to have antivirus, antitumor and antibacterial properties in China and other Asian countries. Studies were carried out to characterize the inhibition of neochamaejasmin B (NCB) on P-glycoprotein (P-gp, ABCB1, MDR1). Rhodamine-123 (R-123) transport and accumulation studies were performed in MDCK-hMDR1 cells. ABCB1 (MDR1) mRNA gene expression and P-gp protein expression were analyzed. Binding selectivity studies based on molecular docking were explored. R-123 transport and accumulation studies in MDCK-hMDR1 cells indicated that NCB inhibited the P-gp-mediated efflux in a concentration-dependent manner. RT-PCR and Western blot demonstrated that the P-gp expression was suppressed by NCB. To investigate the inhibition type of NCB on P-gp, Ki and Ki' values were determined by double-reciprocal plots in R-123 accumulation studies. Since Ki was greater than Ki', the inhibition of NCB on P-gp was likely a mixed type of competitive and non-competitive inhibition. The results were confirmed by molecular docking in our current work. The docking data indicated that NCB had higher affinity to P-gp than to Lig1 ((S)-5,7-dihydroxy-2-(4-hydroxyphenyl)chroman-4-one).

  11. Dioscin strengthens the efficiency of adriamycin in MCF-7 and MCF-7/ADR cells through autophagy induction: More than just down-regulation of MDR1

    PubMed Central

    Wang, Changyuan; Huo, Xiaokui; Wang, Lijuan; Meng, Qiang; Liu, Zhihao; Liu, Qi; Sun, Huijun; Sun, Pengyuan; Peng, Jinyong; Liu, Kexin

    2016-01-01

    The purpose of present study was to investigate the effect of dioscin on activity of adriamycin (ADR) in ADR-sensitive (MCF-7) and ADR-resistant (MCF-7/ADR) human breast cancer cells and to clarify the molecular mechanisms involved. Antiproliferation effect of ADR was enhanced by dioscin in MCF-7 and MCF-7/ADR cells. Dioscin significantly inhibited MDR1 mRNA and protein expression and MDR1 promoter and nuclear factor κ-B (NF-κB) activity in MCF-7/ADR cells. Additionally, inhibitor κB-α (IκB-α) degradation was inhibited by dioscin. Moreover, dioscin induced the formation of vacuoles in the cytoplasm and protein level of LC3-II in MCF-7 and MCF-7/ADR cells. Autophagy inhibitor 3-MA abolished the effect of dioscin on ADR cytotoxicity. Dioscin inhibited phosphorylation of PI3K and Akt, resulting in upregulation of LC3-II expression. In conclusion, dioscin increased ADR chemosensitivity by down-regulating MDR1 expression through NF-κB signaling inhibition in MCF-7/ADR cells. Autophagy was induced by dioscin to ameliorate the cytotoxicity of ADR via inhibition of the PI3K/AKT pathways in MCF-7 and MCF-7/ADR cells. These findings provide evidence in support of further investigation into the clinical application of dioscin as a chemotherapy adjuvant. PMID:27329817

  12. Dissimilar expression of multidrug resistance mdr1 and bcrp by the replication of hepatitis C virus: role of the nonstructural 5A protein.

    PubMed

    W Rivero, C; Rosso, N; Gentile, E; Cuestas, M; Tiribelli, C; Oubiña, J R; Mathet, V L

    2013-04-01

    Multidrug resistance associated with the overexpression of ATP-dependent binding cassette (ABC) proteins is widely accepted as an important cause of treatment failure in patients with neoplastic or infectious diseases. Some of them play also a pivotal role in detoxification processes. Herein, we investigated the effect of hepatitis C virus (HCV) replication and nonstructural 5A (NS5A) protein on the expression and functional activity of two ABC transport proteins: MDR1 and BCRP. RT-quantitative real-time polymerase chain reaction (qPCR) was carried out for mdr1 and bcrp mRNAs in both Huh7 cells expressing NS5A and Huh7.5 cells containing either full-length- or subgenomic-HCV replicon systems. The functional activity of these pumps was studied by performing a dye efflux assay with DiOC2 and Rhodamine 123. A dose-dependent down-regulation of mdr1 expression was documented in Huh7 cells expressing the NS5A protein, as well as in both replicon systems. In contrast, a significant increase of bcrp expression in both systems was recorded, which were in full agreement with the dye efflux assay results. These results warrant further in vivo studies in HCV patients with cholestasis and/or patients that are refractive to the pharmacotherapy due to the activity of these pumps. PMID:23490381

  13. Evaluation of mRNA Expression Levels of cyp51A and mdr1, Candidate Genes for Voriconazole Resistance in Aspergillus flavus

    PubMed Central

    Fattahi, Azam; Zaini, Farideh; Kordbacheh, Parivash; Rezaie, Sasan; Safara, Mahin; Fateh, Roohollah; Farahyar, Shirin; Kanani, Ali; Heidari, Mansour

    2015-01-01

    Background: Voriconazole Resistance (VRC-R) in Aspergillus flavus isolates impacts the management of aspergillosis, since azoles are the first choice for prophylaxis and therapy. However, to the best of our knowledge, the mechanisms underlying voriconazole resistance are poorly understood. Objectives: The present study was designed to evaluate mRNA expression levels of cyp51A and mdr1 genes in voriconazole resistant A. flavus by a Real-Time Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) technique. Materials and Methods: Five A. flavus isolates with resistance to VRC were examined by a RT-PCR approach. Results: Four out of five isolates revealed cyp51A and mdr1 mRNA overexpression. Interestingly, the isolate, which was negative for cyp51A and mdr1 mRNA expression showed a high voriconazole Minimum Inhibitory Concentration (MIC). Furthermore, a computational-based analysis predicted that voriconazole resistance could be mediated through cooperation with a network protein interaction. Conclusions: Our experimental and in silico findings may provide new insight in the complex molecular pathways of drug resistance and also could assist design an efficient therapeutic strategy for aspergillosis treatment. PMID:26865941

  14. Design of a hairpin polyamide, ZT65B, for targeting the inverted CCAAT box (ICB) site in the multidrug resistant (MDR1) gene.

    PubMed

    Buchmueller, Karen L; Taherbhai, Zarmeen; Howard, Cameron M; Bailey, Suzanna L; Nguyen, Binh; O'Hare, Caroline; Hochhauser, Daniel; Hartley, John A; Wilson, W David; Lee, Moses

    2005-12-01

    A novel hairpin polyamide, ZT65B, containing a 3-methylpicolinate moiety was designed to target the inverted CCAAT box (ICB) of the human multidrug resistance 1 gene (MDR1) promoter. Binding of nuclear factor-Y (NF-Y) to the ICB site upregulates MDR1 gene expression and is, therefore, a good target for anticancer therapeutic agents. However, it is important to distinguish amongst different promoter ICB sites so that only specific genes will be affected. All ICB sites have the same sequence but they differ in the sequence of the flanking base pairs, which can be exploited in the design of sequence-specific polyamides. To test this hypothesis, ten ICB-containing DNA hairpins were designed with different flanking base pairs; the sequences ICBa and ICBb were similar to the 3'-ICB site of MDR1 (TGGCT). Thermal-denaturation studies showed that ZT65B effectively targeted ICBa and ICBb (DeltaTM=6.5 and 7.0 degrees C) in preference to the other DNA hairpins (<3.5 degrees C), with the exception of ICBc (5.0 degrees C). DNase I-footprinting assays were carried out with the topoisomerase IIalpha-promoter sequence, which contains five ICB sites; of these, ICB1 and ICB5 are similar to the ICB site of MDR1. ZT65B was found to selectively bind ICB1 and ICB5; footprints were not observed with ICB2, ICB3, or ICB4. A strong, positive induced ligand band at 325 nm in CD studies confirmed that ZT65B binds in the DNA minor groove. The selectivity of ZT65B binding to hairpins that contained the MDR1 ICB site compared to one that did not (ICBd) was confirmed by surface-plasmon studies, and equilibrium constants of 5x10(6)-1x10(7) and 4.6x10(5) M-1 were obtained with ICB1, ICB5,and ICB2 respectively. ZT65B and the previously published JH37 (J. A. Henry, et al. Biochemistry 2004, 43, 12 249-12 257) serve as prototypes for the design of novel polyamides. These can be used to specifically target the subset of ubiquitous gene elements known as ICBs, and thereby affect the expression of one or

  15. Inhibition of MDR1 gene expression and enhancing cellular uptake for effective colon cancer treatment using dual-surface–functionalized nanoparticles

    PubMed Central

    Xiao, Bo; Zhang, Mingzhen; Viennois, Emilie; Zhang, Yuchen; Wei, Na; Baker, Mark T.; Jung, Yunjin; Merlin, Didier

    2015-01-01

    Nanomedicine options for colon cancer therapy have been limited by the lack of suitable carriers capable of delivering sufficient drug into tumors to cause lethal toxicity. To circumvent this limitation, we fabricated a camptothecin (CPT)-loaded poly(lactic-co-glycolic acid) nanoparticle (NP) with dual-surface functionalization—Pluronic F127 and chitosan—for inhibiting multi-drug resistant gene 1 (MDR1) expression and enhancing tumor uptake. The resultant spherical NPs-P/C had a desirable particle size (~268 nm), slightly positive zeta-potential, and the ability to efficiently down-regulate the expression of MDR1. In vitro cytotoxicity tests revealed that the 24 and 48 h IC50 values of NPs-P/C1 were 2.03 and 0.67 µM, respectively, which were much lower than those for free CPT and other NPs. Interestingly, NPs-P/C1 showed the highest cellular uptake efficiency (approximately 85.5%) among the different drug formulations. Most importantly, treatment of colon tumor-bearing mice with various drug formulations confirmed that the introduction of Pluronic F127 and chitosan to the NP surface significantly enhanced the therapeutic efficacy of CPT, induced tumor cell apoptosis, and reduced systemic toxicity. Collectively, these findings suggest that our one-step–fabricated, dual-surface–functionalized NPs may hold promise as a readily scalable and effective drug carrier with clinical potential in colon cancer therapy. PMID:25701040

  16. C1236T polymorphism in MDR1 gene correlates with therapeutic response to imatinib mesylate in Indian patients with chronic myeloid leukaemia.

    PubMed

    Chhikara, Sunita; Sazawal, Sudha; Mishra, Pravas; Chaubey, Rekha; Mahapatra, Manoranjan; Saxena, Renu

    2015-01-01

    Patients with chronic myeloid leukaemia show an excellent response to treatment with imatinib. However, in some patients, the disease is resistant to imatinib. This resistance may be related to the presence of genetic variations on the drug's pharmacokinetics and metabolism. We therefore studied three polymorphisms (C1236T, G2677T and C3435T) in the human multidrug-resistance gene (MDR1) in 86 patients with chronic myeloid leukaemia treated with imatinib. Imatinib resistance was more frequent in patients with TT genotype at locus 1236 than in those with CT/CC genotypes (p=0.003). For the other two loci (G2677T and C3435T), resistance was seen to be higher for TT genotype when compared to GG/GT and CT/CC but it was not statistically significant (p=0.13 and p=0.099). In conclusion, determination of C1236T MDR1 genotype may help to predict response to imatinib therapy in patients with chronic myeloid leukaemia. PMID:27294449

  17. Echinacea purpurea up-regulates CYP1A2, CYP3A4 and MDR1 gene expression by activation of pregnane X receptor pathway

    PubMed Central

    Awortwe, Charles; Manda, Vamshi K.; Avonto, Cristina; Khan, Shabana I.; Khan, Ikhlas A.; Walker, Larry A.; Bouic, Patrick J.; Rosenkranz, Bernd

    2015-01-01

    This study investigated the mechanism underlying Echinacea-mediated induction of CYP1A2, CYP3A4 and MDR1 in terms of human pregnane X receptor (PXR) activation. Crude extracts and fractions of Echinacea purpurea were tested for PXR activation in HepG2 cells by a reporter gene assay. Quantitative real-time PCR was carried out to determine their effects on CYP1A2 and CYP3A4 mRNA expressions. Capsules and fractions were risk ranked as high, intermediate and remote risk of drug-metabolizing enzymes induction based on EC50 values determined for respective CYPs. Fractions F1, F2 and capsule (2660) strongly activated PXR with 5-, 4- and 3.5-fold increase in activity, respectively. Echinacea preparations potentiated up-regulation of CYP1A2, CYP3A4 and MDR1 via PXR activation. Thus E. purpurea preparations cause herb–drug interaction by up-regulating CYP1A2, CYP3A4 and P-gp via PXR activation. PMID:25377539

  18. Influence of borneol and muscone on geniposide transport through MDCK and MDCK-MDR1 cells as blood-brain barrier in vitro model.

    PubMed

    Chen, Zhen-Zhen; Lu, Yang; Du, Shou-Ying; Shang, Ke-Xin; Cai, Cheng-Bo

    2013-11-01

    The objective of this study was (1) to characterize geniposide transport through MDCK and MDCK-MDR1 cell lines to confirm its transport mechanism and (2) to evaluate the effect of borneol and muscone as enhancers of geniposide transport in the BBB models so as to explore the enhancement mechanism. Transport studies of geniposide were performed in both directions, from apical to basolateral and from basolateral to apical sides. Drug concentrations were analyzed by HPLC. Geniposide showed relatively poor absorption in MDCK and MDCK-MDR1 cells, apparent permeability coefficients ranging from 0.323×10(-6) to 0.422×10(-6) cm/s. The in vitro experiments showed that geniposide transport in both directions was not concentration dependent and saturable, indicating purely passive diffusion. The efflux ratio of geniposide was less than 2 in the two cell models, which suggested that geniposide was not P-gp substrates. Geniposide transport in both directions significantly increased when co-administrated with increasing concentrations of borneol and muscone. Actin staining results indicated that borneol and muscone increased geniposide transport in the BBB models may attribute to disassembly effect on tight junction integrity.

  19. Casein Kinase 2 (CK2)-mediated Phosphorylation of Hsp90β as a Novel Mechanism of Rifampin-induced MDR1 Expression.

    PubMed

    Kim, So Won; Hasanuzzaman, Md; Cho, Munju; Heo, Ye Rang; Ryu, Min-Jung; Ha, Na-Young; Park, Hyun June; Park, Hyung-Yeon; Shin, Jae-Gook

    2015-07-01

    The P-glycoprotein (P-gp) encoded by the MDR1 gene is a drug-exporting transporter located in the cellular membrane. P-gp induction is regarded as one of the main mechanisms underlying drug-induced resistance. Although there is great interest in the regulation of P-gp expression, little is known about its underlying regulatory mechanisms. In this study, we demonstrate that casein kinase 2 (CK2)-mediated phosphorylation of heat shock protein 90β (Hsp90β) and subsequent stabilization of PXR is a key mechanism in the regulation of MDR1 expression. Furthermore, we show that CK2 is directly activated by rifampin. Upon exposure to rifampin, CK2 catalyzes the phosphorylation of Hsp90β at the Ser-225/254 residues. Phosphorylated Hsp90β then interacts with PXR, causing a subsequent increase in its stability, leading to the induction of P-gp expression. In addition, inhibition of CK2 and Hsp90β enhances the down-regulation of PXR and P-gp expression. The results of this study may facilitate the development of new strategies to prevent multidrug resistance and provide a plausible mechanism for acquired drug resistance by CK2-mediated regulation of P-gp expression. PMID:25995454

  20. Resveratrol induces AMPK-dependent MDR1 inhibition in colorectal cancer HCT116/L-OHP cells by preventing activation of NF-κB signaling and suppressing cAMP-responsive element transcriptional activity.

    PubMed

    Wang, Ziyuan; Zhang, Long; Ni, Zhenhua; Sun, Jian; Gao, Hong; Cheng, Zhuoan; Xu, Jianhua; Yin, Peihao

    2015-12-01

    Resveratrol, a natural polyphenolic compound found in foods and beverages, has attracted increasing attention in recent years because of its potent chemopreventive and anti-tumor effects. In this study, the effects of resveratrol on the expression of P-glycoprotein/multi-drug resistance protein 1 (P-gp/MDR1), and the underlying molecular mechanisms, were investigated in oxaliplatin (L-OHP)-resistant colorectal cancer cells (HCT116/L-OHP). Resveratrol downregulated MDR1 protein and mRNA expression levels and reduced MDR1 promoter activity. It also enhanced the intracellular accumulation of rhodamine 123, suggesting that resveratrol can reverse multi-drug resistance by downregulating MDR1 expression and reducing drug efflux. Resveratrol treatment also reduced nuclear factor-κB (NF-κB) activity, reduced phosphorylation levels of IκBα, and reduced nuclear translocation of the NF-κB subunit p65. Moreover, downregulation of MDR1 expression and promoter activity was mediated by resveratrol-induced AMP-activated protein kinase (AMPK) phosphorylation. The inhibitory effects of resveratrol on MDR1 expression and cAMP-responsive element-binding protein (CREB) phosphorylation were reversed by AMPKα siRNA transfection. We found that the transcriptional activity of cAMP-responsive element (CRE) was inhibited by resveratrol. These results demonstrated that the inhibitory effects of resveratrol on MDR1 expression in HCT116/L-OHP cells were closely associated with the inhibition of NF-κB signaling and CREB activation in an AMPK-dependent manner.

  1. Expression of HIF-1α and MDR1/P-glycoprotein in refractory mesial temporal lobe epilepsy patients and pharmacoresistant temporal lobe epilepsy rat model kindled by coriaria lactone.

    PubMed

    Li, Yaohua; Chen, Jianbin; Zeng, Tianfang; Lei, Ding; Chen, Lei; Zhou, Dong

    2014-08-01

    Hypoxia-inducible factor-1α (HIF-1α) is thought to mediate pharmacoresistance in tumor by inducing Pgp overexpression. We aimed to investigate the expression of HIF-1α and MDR1/P-glycoprotein in refractory epilepsy, to explore the correlation of HIF-1α with epilepsy multidrug resistance. We collected hippocampus and mesial temporal lobe (MTL) cortex of refractory mesial temporal lobe epilepsy (mTLE) patients that underwent surgery, and established a pharmacoresistant TLE rat model kindled by coriaria lactone. We used real-time quantitative PCR (RQ-PCR) and western blot to investigate expression of HIF-1α and MDR1 in hippocampus and MTL/entorhinal cortex. We found that the expression of HIF-1α and MDR1, at both mRNA and protein levels, were up-regulated in hippocampus and MTL cortex of mTLE patients compared with the control cortex (all P < 0.05), and increased in hippocampus and entorhinal cortex of kindled rat model versus the control group (all P < 0.05). These results demonstrated the overexpression of HIF-1α and MDR1/Pgp in hippocampus and MTL/entorhinal cortex of mTLE patients and the pharmacoresistant TLE rat model. HIF-1α may have a regulatory effect on MDR1 expression in refractory epilepsy, which is probably consistent with MDR mechanism in tumor.

  2. SNP genetic polymorphisms of MDR-1, CYP1A2 and CYPB11 genes in four canine breeds upon toxicological evaluation

    PubMed Central

    Gagliardi, Rosa; Llambí, Silvia

    2015-01-01

    The fields of pharmacogenetics and pharmacogenomics have become increasingly promising regarding the clinical application of genetic data to aid in prevention of adverse reactions. Specific screening tests can predict which animals express modified proteins or genetic sequences responsible for adverse effects associated with a drug. Among the genetic variations that have been investigated in dogs, the multidrug resistance gene (MDR) is the best studied. However, other genes such as CYP1A2 and CYP2B11 control the protein syntheses involved in the metabolism of many drugs. In the present study, the MDR-1, CYP1A2 and CYP2B11 genes were examined to identify SNP polymorphisms associated with these genes in the following four canine breeds: Uruguayan Cimarron, Border Collie, Labrador Retriever and German Shepherd. The results revealed that several SNPs of the CYP1A2 and CYP2B11 genes are potential targets for drug sensitivity investigations. PMID:25797294

  3. Simultaneous Analysis of Multidrug Resistance 1(MDR1) C3435T, G2677T/A, and C1236T Genotypes in Hamadan City Population, West of Iran

    PubMed Central

    Saidijam, Massoud; Mahjub, Hossein; Shabab, Nooshin; Yadegarazari, Reza

    2015-01-01

    Background: One of the limitations in the treatment of common diseases such as cancer chemotherapy is development of multidrug resistance (MDR). Polymorphisms could alter the expression level of MDR1 gene, which plays an important role in MDR. In this research, the frequency of C3435T, C1236T, and G2677T/A polymorphisms of MDR1 gene was investigated in a large group of population from Hamadan city to provide a sample data resource. Methods: Peripheral blood (2 ml) was taken, and DNA extraction was carried out. Multiplexed mutagenically separated PCR, which was followed by polyacrylamide gel electrophoresis and silver staining, was applied to detect the mentioned polymorphisms in 935 individuals. Sequencing performed for confirmation of gel electrophoresis resulted in 10 random cases. In total, alleles and genotypes of 933 persons (776 women and 157 men) were determined. Results: The most frequent alleles of the polymorphisms were: 3435T, C1236, and G2677. The most frequent genotypes were: 3435C/T, 1236C/T, and 2677G/A, and their concurrent presence was also found as the most frequent simultaneous genotypes. There was not any meaningful difference among the prevalence of these genotypes in groups of men and women. Conclusion: Our results were close to those of other studies performed in Iran and compared to the other ethnic groups, which showed more similarity to Asian peoples than Europeans. As an aspect of personalized medicine, it could be used by chemotherapists to improve the routine methods of cancer treatment. PMID:25605491

  4. Inhibition of mTORC2 Induces Cell-Cycle Arrest and Enhances the Cytotoxicity of Doxorubicin by Suppressing MDR1 Expression in HCC Cells

    PubMed Central

    Chen, Bryan Wei; Chen, Wei; Liang, Hui; Liu, Hao; Liang, Chao; Zhi, Xiao; Hu, Li-qiang; Yu, Xia-Zhen; Wei, Tao; Ma, Tao; Xue, Fei; Zheng, Lei; Zhao, Bin; Feng, Xin-Hua; Bai, Xue-li; Liang, Ting-bo

    2016-01-01

    mTOR is aberrantly activated in hepatocellular carcinoma (HCC) and plays pivotal roles in tumorigenesis and chemoresistance. Rapamycin has been reported to exert antitumor activity in HCC and sensitizes HCC cells to cytotoxic agents. However, due to feedback activation of AKT after mTOR complex 1 (mTORC1) inhibition, simultaneous targeting of mTORC1/2 may be more effective. In this study, we examined the interaction between the dual mTORC1/2 inhibitor OSI-027 and doxorubicin in vitro and in vivo. OSI-027 was found to reduce phosphorylation of both mTORC1 and mTORC2 substrates, including 4E-BP1, p70S6K, and AKT (Ser473), and inhibit HCC cell proliferation. Similar to OSI-027 treatment, knockdown of mTORC2 induced G0–G1 phase cell-cycle arrest. In contrast, rapamycin or knockdown of mTORC1 increased phosphorylation of AKT (Ser473), yet had little antiproliferative effect. Notably, OSI-027 synergized with doxorubicin for the antiproliferative efficacy in a manner dependent of MDR1 expression in HCC cells. The synergistic antitumor effect of OSI-027 and doxorubicin was also observed in a HCC xenograft mouse model. Moreover, AKT was required for OSI-027–induced cell-cycle arrest and downregulation of MDR1. Our findings provide a rationale for dual mTORC1/mTORC2 inhibitors, such as OSI-027, as monotherapy or in combination with cytotoxic agents to treat HCC. PMID:26026051

  5. Inhibition of mTORC2 Induces Cell-Cycle Arrest and Enhances the Cytotoxicity of Doxorubicin by Suppressing MDR1 Expression in HCC Cells.

    PubMed

    Chen, Bryan Wei; Chen, Wei; Liang, Hui; Liu, Hao; Liang, Chao; Zhi, Xiao; Hu, Li-Qiang; Yu, Xia-Zhen; Wei, Tao; Ma, Tao; Xue, Fei; Zheng, Lei; Zhao, Bin; Feng, Xin-Hua; Bai, Xue-Li; Liang, Ting-Bo

    2015-08-01

    mTOR is aberrantly activated in hepatocellular carcinoma (HCC) and plays pivotal roles in tumorigenesis and chemoresistance. Rapamycin has been reported to exert antitumor activity in HCC and sensitizes HCC cells to cytotoxic agents. However, due to feedback activation of AKT after mTOR complex 1 (mTORC1) inhibition, simultaneous targeting of mTORC1/2 may be more effective. In this study, we examined the interaction between the dual mTORC1/2 inhibitor OSI-027 and doxorubicin in vitro and in vivo. OSI-027 was found to reduce phosphorylation of both mTORC1 and mTORC2 substrates, including 4E-BP1, p70S6K, and AKT (Ser473), and inhibit HCC cell proliferation. Similar to OSI-027 treatment, knockdown of mTORC2 induced G0-G1 phase cell-cycle arrest. In contrast, rapamycin or knockdown of mTORC1 increased phosphorylation of AKT (Ser473), yet had little antiproliferative effect. Notably, OSI-027 synergized with doxorubicin for the antiproliferative efficacy in a manner dependent of MDR1 expression in HCC cells. The synergistic antitumor effect of OSI-027 and doxorubicin was also observed in a HCC xenograft mouse model. Moreover, AKT was required for OSI-027-induced cell-cycle arrest and downregulation of MDR1. Our findings provide a rationale for dual mTORC1/mTORC2 inhibitors, such as OSI-027, as monotherapy or in combination with cytotoxic agents to treat HCC. Mol Cancer Ther; 14(8); 1805-15. ©2015 AACR. PMID:26026051

  6. In Vivo Quantification of 5-HT2A Brain Receptors in Mdr1a KO Rats with 123I-R91150 Single-Photon Emission Computed Tomography.

    PubMed

    Dumas, Noé; Moulin-Sallanon, Marcelle; Fender, Pascal; Tournier, Benjamin B; Ginovart, Nathalie; Charnay, Yves; Millet, Philippe

    2015-01-01

    Our goal was to identify suitable image quantification methods to image 5-hydroxytryptamine2A (5-HT2A) receptors in vivo in Mdr1a knockout (KO) rats (i.e., P-glycoprotein KO) using 123I-R91150 single-photon emission computed tomography (SPECT). The 123I-R91150 binding parameters estimated with different reference tissue models (simplified reference tissue model [SRTM], Logan reference tissue model, and tissue ratio [TR] method) were compared to the estimates obtained with a comprehensive three-tissue/seven-parameter (3T/7k)-based model. The SRTM and Logan reference tissue model estimates of 5-HT2A receptor (5-HT2AR) nondisplaceable binding potential (BPND) correlated well with the absolute receptor density measured with the 3T/7k gold standard (r > .89). Quantification of 5-HT2AR using the Logan reference tissue model required at least 90 minutes of scanning, whereas the SRTM required at least 110 minutes. The TR method estimates were also highly correlated to the 5-HT2AR density (r > .91) and only required a single 20-minute scan between 100 and 120 minutes postinjection. However, a systematic overestimation of the BPND values was observed. The Logan reference tissue method is more convenient than the SRTM for the quantification of 5-HT2AR in Mdr1a KO rats using 123I-R91150 SPECT. The TR method is an interesting and simple alternative, despite its bias, as it still provides a valid index of 5-HT2AR density. PMID:26105563

  7. Enhanced anti-tumor effects of combined MDR1 RNA interference and human sodium/iodide symporter (NIS) radioiodine gene therapy using an adenoviral system in a colon cancer model

    PubMed Central

    Ahn, S J; Jeon, Y H; Lee, Y J; Lee, Y L; Lee, S-W; Ahn, B-C; Ha, J-H; Lee, J

    2010-01-01

    Using an adenoviral system as a delivery mediator of therapeutic gene, we investigated the therapeutic effects of the use of combined MDR1 shRNA and human NIS (hNIS) radioiodine gene therapy in a mouse colon xenograft model. In vitro uptake of Tc-99m sestamibi was increased approximately two-fold in cells infected with an adenovirus vector that expressed MDR1 shRNA (Ad-shMDR1) and I-125 uptake was 25-fold higher in cells infected with an adenovirus vector that expressed human NIS (Ad-hNIS) as compared with control cells. As compared with doxorubicin or I-131 treatment alone, the combination of doxorubicin and I-131 resulted in enhanced cytotoxicity for both Ad-shMDR1- and Ad-hNIS-infected cells, but not for control cells. In vivo uptake of Tc-99m sestamibi and Tc-99m pertechnetate was twofold and 10-fold higher for Ad-shMDR1 and Ad-hNIS-infected tumors as compared with tumors infected with a control adenovirus construct that expressed β-galactrosidase (Ad-LacZ), respectively. In mice treated with either doxorubicin or I-131 alone, there was a slight delay in tumor growth as compared to mice treated with Ad-LacZ. However, combination therapy with doxorubicin and I-131 induced further significant inhibition of tumor growth as compared with mice treated with Ad-LacZ. We have shown successful therapeutic efficacy of combined MDR shRNA and hNIS radioiodine gene therapy using an adenoviral vector system in a mouse colon cancer model. Adenovirus-mediated cancer gene therapy using MDR1 shRNA and hNIS would be a useful tool for the treatment of cancer cells expressing multi-drug resistant genes. PMID:20186172

  8. Human AP-endonuclease (APE1/Ref-1) and its acetylation regulate YB-1/p300 recruitment and RNA polymerase II loading in the drug induced activation of multidrug resistance gene MDR1

    PubMed Central

    Sengupta, Shiladitya; Mantha, Anil K.; Mitra, Sankar; Bhakat, Kishor K.

    2010-01-01

    Overexpression of human AP-endonuclease (APE1/Ref-1), a key enzyme in the DNA base excision repair (BER) pathway, is often associated with tumor cell resistance to various anticancer drugs. In this study, we examined the molecular basis of transcriptional regulatory (non repair) function of APE1 in promoting resistance to certain types of drugs. We have recently shown that APE1 stably interacts with Y-box-binding protein 1 (YB-1), and acts as its coactivator for the expression of multidrug resistance gene MDR1, thereby causing drug-resistance. Here we show for the first time that APE1 is stably associated with the basic transcription factor RNA polymerase II (RNA pol II) and the coactivator p300 on the endogenous MDR1 promoter. APE1’s depletion significantly reduces YB-1/p300 recruitment to the promoter, resulting in reduced RNA pol II loading. Drug-induced APE1 acetylation which is mediated by p300 enhances formation of acetylated APE1 (AcAPE1)/YB-1/p300 complex on the MDR1 promoter. Enhanced recruitment of this complex increases MDR1 promoter dependent luciferase activity and its endogenous expression. Using APE1 downregulated cells and cells overexpressing wild type APE1 or its nonacetylable mutant we have demonstrated that the loss of APE1’s acetylation impaired MDR1 activation and sensitizes the cells to cisplatin or etoposide. We have thus established the basis for APE1’s acetylation-dependent regulatory function in inducing MDR1-mediated drug resistance. PMID:20856196

  9. CIAPIN1 confers multidrug resistance through up-regulation of MDR-1 and Bcl-L in LoVo/Adr cells and is independent of p53.

    PubMed

    Zhang, Ya-Fei; Li, Xiao-Hua; Shi, Yong-Quan; Wu, Yu-Yun; Li, Ning; He, Qiang; Ji, Qing; Wang, Rong-Quan; Yang, Shi-Ming; Fang, Dian-Chun

    2011-04-01

    Recent investigations discovered that CIAPIN1 might be another drug resistance-associated molecule in cancer cells. However, the underlying mechanisms of CIAPIN1-related multidrug resistance (MDR) remain elusive. In the present study, we investigated the role and possible mechanisms of CIAPIN1 in MDR of human colon carcinoma LoVo/Adr cells which express the wild-type p53 gene. By using small interference RNA and gene transfection techniques, we found that knockdown of CIAPIN1 expression re-sensitized LoVo/Adr cells to anti-cancer drugs and up-regulation of CIAPIN1 in sensitive LoVo cells resulted in a distinct MDR phenotype. We further revealed that CIAPIN1 conferred the MDR phenotype in LoVo/Adr cells through up-regulating expression of MDR-1 (P-gp) and Bcl-xL. Finally, by analyzing the effect of inactivation of wild-type p53 on CIAPIN1-induced up-regulation of P-gp and Bcl-xL, we determined that CIAPIN1 could exhibit its MDR-related function independently of the p53 signaling pathway. Overall, the results presented here further suggest that over-expression of CIAPIN1 is an important mechanism of drug resistance in human cancers, even if not the sole one.

  10. Solution structure of a purine rich hexaloop hairpin belonging to PGY/MDR1 mRNA and targeted by antisense oligonucleotides

    PubMed Central

    Joli, Flore; Bouchemal, Nadia; Laigle, Alain; Hartmann, Brigitte; Hantz, Edith

    2006-01-01

    A preferential target of antisense oligonucleotides directed against human PGY/MDR1 mRNA is a hairpin containing a stem with a G•U wobble pair, capped by the purine-rich 5′r(GGGAUG)3′ hexaloop. This hairpin is studied by multidimensional NMR and restrained molecular dynamics, with special emphasis on the conformation of south sugars and non-standard phosphate linkages evidenced in both the stem and the loop. The hairpin is found to be highly structured. The G•U wobble pair, a strong counterion binding site, displays structural particularities that are characteristic of this type of mismatch. The upper part of the stem undergoes distortions that optimize its interactions with the beginning of the loop. The loop adopts a new fold in which the single-stranded GGGA purine tract is structured in A-like conformation stacked in continuity of the stem and displays an extensive hydrogen bonding surface for recognition. The remarkable hairpin stability results from classical inter- and intra-strand interactions reinforced by numerous hydrogen bonds involving unusual backbone conformations and ribose 2′-hydroxyl groups. Overall, this work emphasizes numerous features that account for the well-ordered structure of the whole hairpin and highlights the loop properties that facilitate interaction with antisense oligonucleotides. PMID:17041234

  11. Cosilencing of PKM-2 and MDR-1 Sensitizes Multidrug-Resistant Ovarian Cancer Cells to Paclitaxel in a Murine Model of Ovarian Cancer.

    PubMed

    Talekar, Meghna; Ouyang, Qijun; Goldberg, Michael S; Amiji, Mansoor M

    2015-07-01

    Tumor multidrug resistance (MDR) is a serious clinical challenge that significantly limits the effectiveness of cytotoxic chemotherapy. As such, complementary therapeutic strategies are being explored to prevent relapse. The altered metabolic state of cancer cells, which perform aerobic glycolysis, represents an interesting target that can enable discrimination between healthy cells and cancer cells. We hypothesized that cosilencing of genes responsible for aerobic glycolysis and for MDR would have synergistic antitumor effect. In this study, siRNA duplexes against pyruvate kinase M2 and multidrug resistance gene-1 were encapsulated in hyaluronic acid-based self-assembling nanoparticles. The particles were characterized for morphology, size, charge, encapsulation efficiency, and transfection efficiency. In vivo studies included biodistribution assessment, gene knockdown confirmation, therapeutic efficacy, and safety analysis. The benefit of active targeting of cancer cells was confirmed by modifying the particles' surface with a peptide targeted to epidermal growth factor receptor, which is overexpressed on the membranes of the SKOV-3 cancer cells. To augment the studies involving transplantation of a paclitaxel-resistant cell line, an in vivo paclitaxel resistance model was developed by injecting repeated doses of paclitaxel following tumor inoculation. The nanoparticles accumulated significantly in the tumors, hindering tumor volume doubling time (P < 0.05) upon combination therapy in both the wild-type (2-fold) and resistant (8-fold) xenograft models. Although previous studies indicated that silencing of MDR-1 alone sensitized MDR ovarian cancer to paclitaxel only modestly, these data suggest that concurrent silencing of PKM-2 improves the efficacy of paclitaxel against MDR ovarian cancer. PMID:25964202

  12. Interrogation of multidrug resistance (MDR1) P-glycoprotein (ABCB1) expression in human pancreatic carcinoma cells: correlation of 99mTc-Sestamibi uptake with western blot analysis.

    PubMed

    Harpstrite, Scott E; Gu, Hannah; Natarajan, Radhika; Sharma, Vijay

    2014-10-01

    Histopathological studies indicate that ∼63% of pancreatic tumors express multidrug resistance (MDR1) P-glycoprotein (Pgp) and its polymorphic variants. However, Pgp expression detected at the mRNA or protein level does not always correlate with functional transport activity. Because Pgp transport activity is affected by specific mutations and the phosphorylation state of the protein, altered or less active forms of Pgp may also be detected by PCR or immunohistochemistry, which do not accurately reflect the status of tumor cell resistance. To interrogate the status of the functional expression of MDR1 Pgp in MiaPaCa-2 and PANC-1 cells, cellular transport studies using Tc-Sestamibi were performed and correlated with western blot analysis. Biochemical transport assays in human pancreatic carcinoma MiaPaCa-2 and PANC-1 cells, human epidermal carcinoma drug-sensitive KB-3-1 cells, and human breast carcinoma MCF-7 cells (negative controls), and human epidermal carcinoma drug-resistant KB-8-5 cells, human breast carcinoma stably transfected with Pgp MCF-7/MDR1Pgp cells, and liver carcinoma HepG2 cells (positive controls) were performed. Protein levels were determined using a monoclonal antibody C219. Tc-Sestamibi demonstrates accumulation in human pancreatic carcinoma MiaPaCa-2 and PANC-1 cells. Uptake profiles are not affected by treatment with LY335979, a Pgp inhibitor, and correlate with western blot analysis. These cellular transport studies indicate an absence of Pgp at a functional level in MiaPaCa-2 and PANC-1 cells. Because major pancreatic tumors originate from the pancreatic duct and Tc-Sestamibi undergoes a dominant hepatobiliary mode of excretion, it would not be a sensitive probe for imaging pancreatic adenocarcinomas. Following interrogation of the functional status of Pgp in other pancreatic carcinoma cells, chemotherapeutic drugs that are also MDR1 substrates could offer alternative therapeutics for treating pancreatic adenocarcinomas.

  13. Changes in the Expression of miR-381 and miR-495 Are Inversely Associated with the Expression of the MDR1 Gene and Development of Multi-Drug Resistance

    PubMed Central

    Xu, Yan; Ohms, Stephen J.; Li, Zhen; Wang, Qiao; Gong, Guangming; Hu, Yiqiao; Mao, Zhiyong; Shannon, M. Frances; Fan, Jun Y.

    2013-01-01

    Multidrug resistance (MDR) frequently develops in cancer patients exposed to chemotherapeutic agents and is usually brought about by over-expression of P-glycoprotein (P-gp) which acts as a drug efflux pump to reduce the intracellular concentration of the drug(s). Thus, inhibiting P-gp expression might assist in overcoming MDR in cancer chemotherapy. MiRNAome profiling using next-generation sequencing identified differentially expressed microRNAs (miRs) between parental K562 cells and MDR K562 cells (K562/ADM) induced by adriamycin treatment. Two miRs, miR-381 and miR-495, that were strongly down-regulated in K562/ADM cells, are validated to target the 3’-UTR of the MDR1 gene. These miRs are located within a miR cluster located at chromosome region 14q32.31, and all miRs in this cluster appear to be down-regulated in K562/ADM cells. Functional analysis indicated that restoring expression of miR-381 or miR-495 in K562/ADM cells was correlated with reduced expression of the MDR1 gene and its protein product, P-gp, and increased drug uptake by the cells. Thus, we have demonstrated that changing the levels of certain miR species modulates the MDR phenotype in leukemia cells, and propose further exploration of the use of miR-based therapies to overcome MDR. PMID:24303078

  14. High frequency of a single nucleotide substitution (c.-6-180T>G) of the canine MDR1/ABCB1 gene associated with phenobarbital-resistant idiopathic epilepsy in Border Collie dogs.

    PubMed

    Mizukami, Keijiro; Yabuki, Akira; Chang, Hye-Sook; Uddin, Mohammad Mejbah; Rahman, Mohammad Mahbubur; Kushida, Kazuya; Kohyama, Moeko; Yamato, Osamu

    2013-01-01

    A single nucleotide substitution (c.-6-180T>G) associated with resistance to phenobarbital therapy has been found in the canine MDR1/ABCB1 gene in Border Collies with idiopathic epilepsy. In the present study, a PCR-restriction fragment length polymorphism assay was developed for genotyping this mutation, and a genotyping survey was carried out in a population of 472 Border Collies in Japan to determine the current allele frequency. The survey demonstrated the frequencies of the T/T wild type, T/G heterozygote, and G/G mutant homozygote to be 60.0%, 30.3%, and 9.8%, respectively, indicating that the frequency of the mutant G allele is extremely high (24.9%) in Border Collies. The results suggest that this high mutation frequency of the mutation is likely to cause a high prevalence of phenobarbital-resistant epilepsy in Border Collies.

  15. Investigation of utility of cerebrospinal fluid drug concentration as a surrogate for interstitial fluid concentration using microdialysis coupled with cisternal cerebrospinal fluid sampling in wild-type and Mdr1a(-/-) rats.

    PubMed

    Nagaya, Yoko; Nozaki, Yoshitane; Takenaka, Osamu; Watari, Ryuji; Kusano, Kazutomi; Yoshimura, Tsutomu; Kusuhara, Hiroyuki

    2016-02-01

    In drug discovery, the cerebrospinal fluid (CSF) drug concentration (CCSF) has been used as a surrogate for the interstitial fluid (ISF) concentration (CISF). However, the CCSF-to-CISF gradient suggested for P-glycoprotein (P-gp) substrates in rodents causes uncertainty in CISF estimations and subsequent pharmacokinetic-pharmacodynamic analyses. To evaluate the utility of CCSF as a surrogate for CISF, this study directly compared the CCSF with the CISF of 12 compounds, including P-gp substrates, under steady-state conditions in wild-type and Mdr1a(-/-) rats using microdialysis coupled with cisternal CSF sampling. In wild-type rats, the ISF-to-unbound plasma (Kp,uu,ISF) and CSF-to-unbound plasma (Kp,uu,CSF) concentration ratios of the P-gp substrates, except for metoclopramide, were lower than those of the non-P-gp substrates, and the Kp,uu,CSF values were within or close to 3-fold of the Kp,uu,ISF values for all the compounds examined. The Kp,uu,CSF values of the selected P-gp substrates increased in Mdr1a(-/-) rats with a similar magnitude to the Kp,uu,ISF values, resulting in the Kp,uu,CSF-to-Kp,uu,ISF ratios being unchanged. These results suggested that P-gp-mediated active efflux at the blood-brain barrier is a major determinant not only for CISF, but also for CCSF, and that CCSF can be used as a surrogate for CISF even for P-gp substrates in rats.

  16. Fucoxanthin Attenuates Rifampin-Induced Cytochrome P450 3A4 (CYP3A4) and Multiple Drug Resistance 1 (MDR1) Gene Expression Through Pregnane X Receptor (PXR)-Mediated Pathways in Human Hepatoma HepG2 and Colon Adenocarcinoma LS174T Cells

    PubMed Central

    Liu, Cheng-Ling; Lim, Yun-Ping; Hu, Miao-Lin

    2012-01-01

    Pregnane X receptor (PXR) has been reported to regulate the expression of drug-metabolizing enzymes, such as the cytochrome P450 3A (CYP3A) family and transporters, such as multiple drug resistance 1 (MDR1). Fucoxanthin, the major carotenoid in brown sea algae, is a putative chemopreventive agent. In this study, we determined whether fucoxanthin could overcome drug resistance through attenuation of rifampin-induced CYP3A4 and MDR1 gene expression by PXR-mediated pathways in HepG2 hepatoma cells. We found that fucoxanthin (1–10 μM) significantly attenuated rifampin (20 μM)-induced CYP3A4, MDR1 mRNA and CYP3A4 protein expression at 24 h of incubation. Mechanistically, fucoxanthin strongly attenuated the PXR-mediated CYP3A4 promoter activity in HepG2 cells. In addition, fucoxanthin attenuated constitutive androstane receptor (CAR)- and rPXR-mediated CYP3A4 promoter activity in this cell line. Using the mammalian two-hybrid assay, we found that fucoxanthin significantly decreased the interaction between PXR and SRC-1, a PXR co-activator. Thus, fucoxanthin can decrease rifampin-induced CYP3A4 and MDR1 expression through attenuation of PXR-mediated CYP3A4 promoter activation and interaction between PXR and co-activator. These findings could lead to potentially important new therapeutic and dietary approaches to reduce the frequency of adverse drug reactions. PMID:22363234

  17. [The Arabic influence in the "Colóquios dos simples e drogas da India" of Garcia da Orta].

    PubMed

    Ricordel, Joëlle

    2015-09-01

    The "Colóquios dos simples e drogas he cousas medicinais de Índia" (Conversations on the simples, drugs and medicinal substances of India) (1563) of Garcia da Orta is a botanical and pharmacognosy book. The author is a Portuguese physician who studied in the Spanish universities and practiced medicine mainly in India. He studies in short chapters presented in the form of dialogues about sixty simples. Sources to which he refers are indicative of a "classical" training, but also the mark of a curious and open mind to different cultures. The Arabic sources are numerous and mainly concern the identification of substances by abundant synonyms of their names in foreign languages and different medicinal uses that may have been done by the ancient physicians. However, Da Orta is critical with respect to these sources, seeking contradictions and differences of opinion among authors. He confronts them with the oral information collected thanks to a wide network of contacts. PMID:26529894

  18. [The Arabic influence in the "Colóquios dos simples e drogas da India" of Garcia da Orta].

    PubMed

    Ricordel, Joëlle

    2015-09-01

    The "Colóquios dos simples e drogas he cousas medicinais de Índia" (Conversations on the simples, drugs and medicinal substances of India) (1563) of Garcia da Orta is a botanical and pharmacognosy book. The author is a Portuguese physician who studied in the Spanish universities and practiced medicine mainly in India. He studies in short chapters presented in the form of dialogues about sixty simples. Sources to which he refers are indicative of a "classical" training, but also the mark of a curious and open mind to different cultures. The Arabic sources are numerous and mainly concern the identification of substances by abundant synonyms of their names in foreign languages and different medicinal uses that may have been done by the ancient physicians. However, Da Orta is critical with respect to these sources, seeking contradictions and differences of opinion among authors. He confronts them with the oral information collected thanks to a wide network of contacts.

  19. Pincharse sin infectarse: estrategias para prevenir la infección por el VIH y el VHC entre usuarios de drogas inyectables

    PubMed Central

    MATEU-GELABERT, P.; FRIEDMAN, S.; SANDOVAL, M.

    2011-01-01

    Resumen Objetivo Desde principios de los noventa, en la ciudad de Nueva York se han implementado con éxito programas para reducir la incidencia del virus de la inmunodeficiencia humana (VIH) y, en menor medida, del virus de la hepatitis C (VHC). A pesar de ello, aproximadamente el 70% de los usuario de drogas inyectables (UDI) están infectados por el VHC. Queremos investigar cómo el 30% restante se las ha arreglado para no infectarse. El Staying safe (nombre original del estudio) explora los comportamientos y mecanismos que ayudan a evitar la infección por el VHC y el VIH a largo plazo. Material y métodos Hemos utilizado el concepto de «desviación positiva» aplicado en otros campos de salud pública. Estudiamos las estrategias, prácticas y tácticas de prevención de aquellos UDI que, viviendo en contextos de alta prevalencia, se mantienen sin infectar por VIH y el VHC, a pesar de haberse inyectado heroína durante años. Los resultados preliminares presentados en este artículo incluyen el análisis de las entrevistas realizadas a 25 UDI (17 doble negativos, 3 doble positivos y 5 con infección por el VHC y sin infección por el VIH). Se usaron entrevistas semiestructuradas que exploraban con detalle la historia de vida de los sujetos, incluyendo su consumo de drogas, redes sociales, contacto con instituciones, relaciones sexuales y estrategias de protección y vigilancia. Resultados La intencionalidad es importante para no infectarse, especialmente durante períodos de involución (períodos donde hay un deterioro económico y/o social que llevan al que se inyecta a situaciones de mayor riesgo). Presentamos tres dimensiones independientes de intencionalidad que conllevan comportamientos que pueden ayudar a prevenir la infección: a) evitar «el mono» (síntomas de abstención) asegurando el acceso a la droga; b) «llevarlo bien» para no convertirse en un junkie y así evitar la «muerte social» y la falta de acceso a los recursos, y c) seguir sin

  20. Multiple Origins of Mutations in the mdr1 Gene—A Putative Marker of Chloroquine Resistance in P. vivax

    PubMed Central

    Schousboe, Mette L.; Ranjitkar, Samir; Rajakaruna, Rupika S.; Amerasinghe, Priyanie H.; Morales, Francisco; Pearce, Richard; Ord, Rosalyn; Leslie, Toby; Rowland, Mark; Gadalla, Nahla B.; Konradsen, Flemming; Bygbjerg, Ib C.; Roper, Cally; Alifrangis, Michael

    2015-01-01

    Background Chloroquine combined with primaquine has been the recommended antimalarial treatment of Plasmodium vivax malaria infections for six decades but the efficacy of this treatment regimen is threatened by chloroquine resistance (CQR). Single nucleotide polymorphisms (SNPs) in the multidrug resistance gene, Pvmdr1 are putative determinants of CQR but the extent of their emergence at population level remains to be explored. Objective In this study we describe the prevalence of SNPs in the Pvmdr1 among samples collected in seven P. vivax endemic countries and we looked for molecular evidence of drug selection by characterising polymorphism at microsatellite (MS) loci flanking the Pvmdr1 gene. Methods We examined the prevalence of SNPs in the Pvmdr1 gene among 267 samples collected from Pakistan, Afghanistan, Sri Lanka, Nepal, Sudan, São Tomé and Ecuador. We measured and diversity in four microsatellite (MS) markers flanking the Pvmdr1 gene to look evidence of selection on mutant alleles. Results SNP polymorphism in the Pvmdr1 gene was largely confined to codons T958M, Y976F and F1076L. Only 2.4% of samples were wildtype at all three codons (TYF, n = 5), 13.3% (n = 28) of the samples were single mutant MYF, 63.0% of samples (n = 133) were double mutant MYL, and 21.3% (n = 45) were triple mutant MFL. Clear geographic differences in the prevalence of these Pvmdr mutation combinations were observed. Significant linkage disequilibrium (LD) between Pvmdr1 and MS alleles was found in populations sampled in Ecuador, Nepal and Sri Lanka, while significant LD between Pvmdr1 and the combined 4 MS locus haplotype was only seen in Ecuador and Sri Lanka. When combining the 5 loci, high level diversity, measured as expected heterozygosity (He), was seen in the complete sample set (He = 0.99), while He estimates for individual loci ranged from 0.00–0.93. Although Pvmdr1 haplotypes were not consistently associated with specific flanking MS alleles, there was significant differentiation between geographic sites which could indicate directional selection through local drug pressure. Conclusions Our observations suggest that Pvmdr1 mutations emerged independently on multiple occasions even within the same population. In Sri Lanka population analysis at multiple sites showed evidence of local selection and geographical dispersal of Pvmdr1 mutations between sites. PMID:26539821

  1. TOXICOKINETICS OF BDE 47 IN FEMALE MICE: EFFECTS OF DOSE, ROUTE OF EXPOSURE, AND MDR1 TRANSPORTER

    EPA Science Inventory

    Introduction
    2,2',4,4'-Tetrabromodiphenyl ether (BDE 47) is a polybrominated diphenyl ether (PBDE) congener used in a class of brominated flame retardants (BFRs) commonly used in a variety of highly flammable consumer goods. Concern for the effects of PBDEs has increased sign...

  2. The farnesyl transferase inhibitor, tipifarnib, is a potent inhibitor of the MDR1 gene product, P-glycoprotein, and demonstrates significant cytotoxic synergism against human leukemia cell lines.

    PubMed

    Medeiros, B C; Landau, H J; Morrow, M; Lockerbie, R O; Pitts, T; Eckhardt, S G

    2007-04-01

    Farnesyl transferase inhibitors (FTIs) target signal-transduction pathways responsible for the proliferation and survival of hematologic malignancies, including acute myelogenous leukemias (AML). Lonafarnib has been shown to be a potent inhibitor of Pgp-mediated drug efflux. On the basis of these findings, we examined the Pgp-inhibitory properties of tipifarnib and assessed its activity when combined with anthracyclines. The effects of tipifarnib on cell proliferation, induction of apoptosis and inhibition of Pgp-mediated anthracycline efflux were analyzed in two human leukemia cell lines overexpressing Pgp (CCRF-CEM and KG1a). Measurement of residual daunorubicin (DNR)-mediated fluorescence after incubation with DNR and tipifarnib demonstrated that tipifarnib significantly inhibited DNR efflux in CCRF-CEM with an IC(50) value less than 0.5 microM. Proliferation and apoptosis assays after exposure to DNR in the presence or absence of tipifarnib demonstrated synergistic inhibition of cellular proliferation, and induction of apoptosis with the combination of tipifarnib and DNR. Similar data was obtained with an enantiomer of tipifarnib that possesses no FTI activity. Incubation with tipifarnib and DNR did not interfere with inhibition of the post-translational processing of HDJ-2. These data suggest that tipifarnib possesses Pgp-inhibitory activity in addition to its FTI activity. In high risk and refractory patients these properties may be exploited as a dual targeting mechanism in the therapy of AML.

  3. Impact of Genetic Polymorphisms of ABCB1 (MDR1, P-Glycoprotein) on Drug Disposition and Potential Clinical Implications: Update of the Literature.

    PubMed

    Wolking, Stefan; Schaeffeler, Elke; Lerche, Holger; Schwab, Matthias; Nies, Anne T

    2015-07-01

    ATP-binding cassette transporter B1 (ABCB1; P-glycoprotein; multidrug resistance protein 1) is an adenosine triphosphate (ATP)-dependent efflux transporter located in the plasma membrane of many different cell types. Numerous structurally unrelated compounds, including drugs and environmental toxins, have been identified as substrates. ABCB1 limits the absorption of xenobiotics from the gut lumen, protects sensitive tissues (e.g. the brain, fetus and testes) from xenobiotics and is involved in biliary and renal secretion of its substrates. In recent years, a large number of polymorphisms of the ABCB1 [ATP-binding cassette, sub-family B (MDR/TAP), member 1] gene have been described. The variants 1236C>T (rs1128503, p.G412G), 2677G>T/A (rs2032582, p.A893S/T) and 3435C>T (rs1045642, p.I1145I) occur at high allele frequencies and create a common haplotype; therefore, they have been most widely studied. This review provides an overview of clinical studies published between 2002 and March 2015. In summary, the effect of ABCB1 variation on P-glycoprotein expression (messenger RNA and protein expression) and/or activity in various tissues (e.g. the liver, gut and heart) appears to be small. Although polymorphisms and haplotypes of ABCB1 have been associated with alterations in drug disposition and drug response, including adverse events with various ABCB1 substrates in different ethnic populations, the results have been majorly conflicting, with limited clinical relevance. Future research activities are warranted, considering a deep-sequencing approach, as well as well-designed clinical studies with appropriate sample sizes to elucidate the impact of rare ABCB1 variants and their potential consequences for effect sizes.

  4. New immunohistochemical "sandwich" staining method for mdr1 P-glycoprotein detection with JSB-1 monoclonal antibody in formalin-fixed, paraffin-embedded human tissues.

    PubMed Central

    Tóth, K.; Vaughan, M. M.; Slocum, H. K.; Arredondo, M. A.; Takita, H.; Baker, R. M.; Rustum, Y. M.

    1994-01-01

    We have developed a new immunoperoxidase "sandwich" staining method for amplified detection of P-glycoprotein (Pgp) that is suitable for use on formalin-fixed, paraffin-embedded (conventional) tissue sections. This was accomplished by substantially changing the procedure described by Chan (1988) so as to increase specific staining intensity and to decrease nonspecific background staining. To determine the most appropriate primary antibody for the assay, we compared the immunoreactivity of JSB-1, C494, and C219 monoclonal antibodies recognizing internal epitopes of Pgp, and MRK16 and 4E3 monoclonal antibodies recognizing external epitopes of Pgp. Paraffin sections of Pgp-positive normal human tissues (adrenal, liver, kidney, and brain), of renal tumors, and of cell pellets of sensitive and multidrug resistant human tumor cell lines (MCF-7, KB) were used for comparisons. Immunostaining was excellent with JSB-1, moderate with C494, and very weak with C219. MRK16 and 4E3 showed no reaction. Nonspecific background staining was reduced by 1) omitting immunoglobulin G from secondary antibodies; 2) decreasing the concentration of peroxidase-antiperoxidase complex; and 3) utilizing casein solution for blocking and washing. Pretreatment of sections before immunostaining was also simplified. Using JSB-1, the threshold for detection of elevated Pgp corresponded to less than two-fold relative resistance to doxorubicin. Applying this method, we found two of 26 non-small cell lung cancers were positive for Pgp, consistent with previous results of others using frozen sections. This new immunoperoxidase sandwich staining method using JSB-1 now allows reliable Pgp detection in sections of formalin-fixed, paraffin-embedded (archived) surgical specimens and small biopsy materials commonly used for diagnostic purposes. Images Figure 2 Figure 3 PMID:7508682

  5. Escuelas sin Drogas. Como Actuar. Edicion 1992. (Schools without Drugs. What Works. 1992 Edition).

    ERIC Educational Resources Information Center

    Department of Education, Washington, DC.

    Across the United States, schools and communities have found ways to turn the tide in the battle against drugs. This guidebook describes the methods they have used and the actions they have taken. The first section, "Children and Drugs" outlines the nature and extent of the drug problem and summarizes the latest research on the effects of drugs on…

  6. Inmunoterapias para las adicciones a las drogas Immunotherapies for Drug Addictions

    PubMed Central

    Montoya, Iván D.

    2008-01-01

    Immunotherapies in the form of vaccines (active immunization) or monoclonal antibodies (passive immunization) appear safe and a promising treatment approaches for some substance-related disorders. The mechanism of action of the antibody therapy is by preventing the rapid entry of drugs of abuse into the central nervous system. In theory, immunotherapies could have several clinical applications. Monoclonal antibodies may be useful to treat drug overdoses and prevent the neurotoxic effects of drugs by blocking the access of drugs to the brain. Vaccines may help to prevent the development of addiction, initiate drug abstinence in those already addicted to drugs, or prevent drug use relapse by reducing the pharmacological effects and rewarding properties of the drugs of abuse on the brain. Passive immunization with monoclonal antibodies has been investigated for cocaine, methamphetamine, nicotine, and phencyclidine (PCP). Active immunization with vaccines has been studied for cocaine, heroin, methamphetamine, and nicotine. These immunotherapies seem promising therapeutic tools and are at different stages in their development before they can be approved by regulatory agencies for the treatment of substance-related disorders. The purpose of this article is to review the current immunotherapy approaches with emphasis on the risks and benefits for the treatment of these disorders. PMID:18551223

  7. Creciendo Sin Drogas: Guia de Prevencion para Padres (Growing Up Drug-Free: A Parent's Guide to Prevention).

    ERIC Educational Resources Information Center

    Office of Elementary and Secondary Education (ED), Washington, DC. Safe and Drug Free Schools Program.

    This publication is part of the Department of Education's ongoing effort to provide information to emerging populations in their native language on how to create and maintain drug-free and safe schools across the nation. Throughout the publication are personal stories and artwork of elementary and secondary school students that promote the message…

  8. A cis-active regulatory gene in the mouse: direct demonstration of cis-active control of the rate of enzyme subunit synthesis

    SciTech Connect

    Bernstine, E.G.; Koh, C.

    1980-07-01

    Mouse mitochondrial malic enzyme (L-malate:NADP/sup +/ oxidoreductase (oxaloacetate-decarboxylating), EC1.1.1.40) is a tetrameric protein. Two alleles of the structural gene (Mod-2) are known which code for electrophoretically distinct enzyme subunits: Mod-2/sup a/ and Mod-2/sup b/. A regulatory gene (Mdr-1), closely linked to Mod-2 on chromosome 7, determines the rate of mitochondrial malic enzyme synthesis in brain. Two alleles of Mdr-1 are known: Mdr-1/sup a/ (high activity) and Mdr-1/sup b/ (low activity). By pulse-labeling with (/sup 35/S)methionine, immune precipitation, and isoelectric focusing under dissociating conditions, we have measured the relative rates of synthesis of the two types of enzyme subunit in animals of genotypes Mdr-1/sup a/ Mod-2/sup a//Mdr-1/sup a/ Mod-2/sup b/ and Mdr-1/sup a/ Mod-2/sup a//Mdr-1/sup b/ Mod-2/sup b/. The results show that in the former animals both types of subunit are made at an identical rate, whereas in the latter animals the Mod-2/sup a/ gene product is synthesized at a rate 2.2 times that of the Mod-2/sup b/-coded subunit. Thus we have unambiguously demonstrated that Mdr-1 is cis-active in its control of the expression of the Mod-2 structural gene.

  9. Targeting glucosylceramide synthase induction of cell surface globotriaosylceramide (Gb3) in acquired cisplatin-resistance of lung cancer and malignant pleural mesothelioma cells

    SciTech Connect

    Tyler, Andreas; Johansson, Anders; Karlsson, Terese; Gudey, Shyam Kumar; Brännström, Thomas; Grankvist, Kjell; Behnam-Motlagh, Parviz

    2015-08-01

    Background: Acquired resistance to cisplatin treatment is a caveat when treating patients with non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MPM). Ceramide increases in response to chemotherapy, leading to proliferation arrest and apoptosis. However, a tumour stress activation of glucosylceramide synthase (GCS) follows to eliminate ceramide by formation of glycosphingolipids (GSLs) such as globotriaosylceramide (Gb3), the functional receptor of verotoxin-1. Ceramide elimination enhances cell proliferation and apoptosis blockade, thus stimulating tumor progression. GSLs transactivate multidrug resistance 1/P-glycoprotein (MDR1) and multidrug resistance-associated protein 1 (MRP1) expression which further prevents ceramide accumulation and stimulates drug efflux. We investigated the expression of Gb3, MDR1 and MRP1 in NSCLC and MPM cells with acquired cisplatin resistance, and if GCS activity or MDR1 pump inhibitors would reduce their expression and reverse cisplatin-resistance. Methods: Cell surface expression of Gb3, MDR1 and MRP1 and intracellular expression of MDR1 and MRP1 was analyzed by flow cytometry and confocal microscopy on P31 MPM and H1299 NSCLC cells and subline cells with acquired cisplatin resistance. The effect of GCS inhibitor PPMP and MDR1 pump inhibitor cyclosporin A for 72 h on expression and cisplatin cytotoxicity was tested. Results: The cisplatin-resistant cells expressed increased cell surface Gb3. Cell surface Gb3 expression of resistant cells was annihilated by PPMP whereas cyclosporin A decreased Gb3 and MDR1 expression in H1299 cells. No decrease of MDR1 by PPMP was noted in using flow cytometry, whereas a decrease of MDR1 in H1299 and H1299res was indicated with confocal microscopy. No certain co-localization of Gb3 and MDR1 was noted. PPMP, but not cyclosporin A, potentiated cisplatin cytotoxicity in all cells. Conclusions: Cell surface Gb3 expression is a likely tumour biomarker for acquired cisplatin

  10. Role of P-glycoprotein in mediating rivastigmine effect on amyloid-β brain load and related pathology in Alzheimer's disease mouse model.

    PubMed

    Mohamed, Loqman A; Keller, Jeffrey N; Kaddoumi, Amal

    2016-04-01

    Recently, we showed that rivastigmine decreased amyloid-β (Aβ) brain load in aged rats by enhancing its clearance across the blood-brain barrier (BBB) via upregulation of P-glycoprotein (P-gp) and low-density lipoprotein receptor-related protein 1 (LRP1). Here, we extend our previous work to clarify P-gp role in mediating rivastigmine effect on Aβ brain levels and neuroprotection in a mouse model of Alzheimer's disease (AD) that expresses different levels of P-gp. APPSWE mice were bred with mdr1a/b knockout mice to produce littermates that were divided into three groups; APP(+)/mdr1(+/+), APP(+)/mdr1(+/-) and APP(+)/mdr1(-/-). Animals received rivastigmine treatment (0.3mg/kg/day) or vehicle for 8weeks using Alzet osmotic mini-pumps. ELISA analysis of brain homogenates for Aβ showed rivastigmine treatment to significantly decrease Aβ brain load in APP(+)/mdr1(+/+) by 25% and in APP(+)/mdr1(+/-) mice by 21% compared to their vehicle treated littermates, but not in APP(+)/mdr1(-/-) mice. In addition, rivastigmine reduced GFAP immunostaining of astrocytes by 50% and IL-1β brain level by 43% in APP(+)/mdr1(+/+) mice, however its effect was less pronounced in P-gp knockout mice. Moreover, rivastigmine demonstrated a P-gp expression dependent neuroprotective effect that was highest in APP(+)/mdr1(+/+)>APP(+)/mdr1(+/-)>APP(+)/mdr1(-/-) as determined by expression of synaptic markers PSD-95 and SNAP-25 using Western blot analysis. Collectively, our results suggest that P-gp plays important role in mediating rivastigmine non-cholinergic beneficial effects, including Aβ brain load reduction, neuroprotective and anti-inflammatory effects in the AD mouse models. PMID:26780497

  11. Limited oral bioavailability and active epithelial excretion of paclitaxel (Taxol) caused by P-glycoprotein in the intestine

    PubMed Central

    Sparreboom, Alex; van Asperen, Judith; Mayer, Ulrich; Schinkel, Alfred H.; Smit, Johan W.; Meijer, Dirk K. F.; Borst, Piet; Nooijen, Willem J.; Beijnen, Jos H.; van Tellingen, Olaf

    1997-01-01

    In mice, the mdr1a and mdr1b genes encode drug-transporting proteins that can cause multidrug resistance in tumor cells by lowering intracellular drug levels. These P-glycoproteins are also found in various normal tissues such as the intestine. Because mdr1b P-glycoprotein is not detectable in the intestine, mice with a homozygously disrupted mdr1a gene [mdr1a(−/−) mice] do not contain functional P-glycoprotein in this organ. We have used these mdr1a(−/−) mice to study the effect of gut P-glycoprotein on the pharmacokinetics of paclitaxel. The area under the plasma concentration-time curves was 2- and 6-fold higher in mdr1a(−/−) mice than in wild-type (wt) mice after i.v. and oral drug administration, respectively. Consequently, the oral bioavailability in mice receiving 10 mg paclitaxel per kg body weight increased from only 11% in wt mice to 35% in mdr1a(−/−) mice. The cumulative fecal excretion (0–96 hr) was markedly reduced from 40% (after i.v. administration) and 87% (after oral administration) of the administered dose in wt mice to below 3% in mdr1a(−/−) mice. Biliary excretion was not significantly different in wt and mdr1a(−/−) mice. Interestingly, after i.v. drug administration of paclitaxel (10 mg/kg) to mice with a cannulated gall bladder, 11% of the dose was recovered within 90 min in the intestinal contents of wt mice vs. <3% in mdr1a(−/−) mice. We conclude that P-glycoprotein limits the oral uptake of paclitaxel and mediates direct excretion of the drug from the systemic circulation into the intestinal lumen. PMID:9050899

  12. Quantitative Targeted Absolute Proteomics of Transporters and Pharmacoproteomics-Based Reconstruction of P-Glycoprotein Function in Mouse Small Intestine.

    PubMed

    Akazawa, Takanori; Uchida, Yasuo; Tachikawa, Masanori; Ohtsuki, Sumio; Terasaki, Tetsuya

    2016-07-01

    The purpose of this study was to investigate whether a pharmacokinetic model integrating in vitro mdr1a efflux activity (which we previously reported) with in vitro/in vivo differences in protein expression level can reconstruct intestinal mdr1a function. In situ intestinal permeability-surface area product ratio between wild-type and mdr1a/1b (-/-) mice is one of the parameters used to describe intestinal mdr1a function. The reconstructed ratios of six mdr1a substrates (dexamethasone, digoxin, loperamide, quinidine, verapamil, vinblastine) and one nonsubstrate (diazepam) were consistent with the observed values reported by Adachi et al. within 2.1-fold difference. Thus, intestinal mdr1a function can be reconstructed by our pharmacoproteomic modeling approach. Furthermore, we evaluated regional differences in protein expression levels of mouse intestinal transporters. Sixteen (mdr1a, mrp4, bcrp, abcg5, abcg8, glut1, 4f2hc, sglt1, lat2, pept1, mct1, slc22a18, ostβ, villin1, Na(+)/K(+)-ATPase, γ-gtp) out of 46 target molecules were detected by employing our established quantitative targeted absolute proteomics technique. The protein expression amounts of mdr1a and bcrp increased progressively from duodenum to ileum. Sglt1, lat2, and 4f2hc were highly expressed in jejunum and ileum. Mct1 and ostβ were highly expressed in ileum. The quantitative expression profiles established here should be helpful to understand and predict intestinal transporter functions. PMID:27276518

  13. Tips for Parents on Keeping Children Drug Free = Consejos para Los Padres Sobre Como Mantener a Los Hijos Libres de La Droga.

    ERIC Educational Resources Information Center

    Department of Education, Washington, DC. Office of Intergovernmental and Interagency Affairs.

    Research shows that recent trends in youth drug use have stabilized; however, the rates of use remain at high levels. It has been shown that the earlier drug use is initiated, the more likely a person is to develop drug problems later in life. Youth substance abuse may lead to many other problems that affect not only the child, but also the…

  14. Previniendo el Uso de Drogas entre Ninos y Adolescentes: Una Guia Basada en Investigaciones (Preventing Drug Use among Children and Adolescents: A Research-Based Guide).

    ERIC Educational Resources Information Center

    Sloboda, Zili; David, Susan L.

    This question and answer guide provides an overview of the research on the origins and pathways of drug abuse, the basic principles derived from effective drug abuse prevention research, and the application of research results to the prevention of drug use among young people. The basic principles derived from drug abuse prevention research are…

  15. Identification of galectin-1 as a novel mediator for chemoresistance in chronic myeloid leukemia cells

    PubMed Central

    Zeng, Xiang-Feng; Wu, Jian-Zhang; Zhu, Cai-Rong; Huang, Tao; Tan, Xiang-Peng; Lin, Xiao-Mian; Yang, Qi; Wang, Ji-Zhong; Li, Xiao-Kun; Wu, Xiao-Ping

    2016-01-01

    Multidrug resistance protein-1 (MDR1) has been proven to be associated with the development of chemoresistance to imatinib (Glivec, STI571) which displays high efficacy in treatment of BCR-ABL-positive chronic myelogenous leukemia (CML). However, the possible mechanisms of MDR1 modulation in the process of the resistance development remain to be defined. Herein, galectin-1 was identified as a candidate modulator of MDR1 by proteomic analysis of a model system of leukemia cell lines with a gradual increase of MDR1 expression and drug resistance. Coincidently, alteration of galectin-1 expression triggers the change of MDR1 expression as well as the resistance to the cytotoxic drugs, suggesting that augment of MDR1 expression engages in galectin-1-mediated chemoresistance. Moreover, we provided the first data showing that NF-κB translocation induced by P38 MAPK activation was responsible for the modulation effect of galectin-1 on MDR1 in the chronic myelogenous leukemia cells. Galectin-1 might be considered as a novel target for combined modality therapy for enhancing the efficacy of CML treatment with imatinib. PMID:27050374

  16. Overexpression of EPS8 is associated with poor prognosis in patients with acute lymphoblastic leukemia.

    PubMed

    He, Ying-Zhi; Liang, Zhao; Wu, Mei-Rong; Wen, Qi; Deng, Lan; Song, Chao-Yang; Wu, Bing-Yi; Tu, San-Fang; Huang, Rui; Li, Yu-Hua

    2015-06-01

    Molecular markers have become an invaluable tool in monitoring disease status particularly of leukemias, as bone marrow samples can be easily collected for analysis during all stages of disease development including diagnosis, treatment, and follow-up. Two genes that have been used as prognostic markers in acute leukemia are Wilms' tumor (WT1) and multidrug resistance-1 (MDR1). A novel gene, epidermal growth factor receptor pathway substrate 8 (EPS8), is often over-expressed and associated with poor outcome in some solid tumor types. However, whether EPS8 is also associated with the development of acute lymphoblastic leukemia (ALL) is unclear. Here, quantitative real-time PCR was used to evaluate the expression of EPS8, MDR1, and WT1 in bone marrow samples of adult ALL patients (n=107) and non-leukemia controls (n=22). EPS8, MDR1, and WT1 were detected in ALL patients, and significant correlations were found between expression profiles for EPS8 and MDR1, EPS8 and WT1, and MDR1 and WT1. In general, high expression of EPS8, MDR1, or WT1 in patients was associated with a higher risk of relapse. Furthermore, when patients were stratified based on high or low expression of the genes, Kaplan-Meier survival analysis indicated that disease-free survival of patients with the high-EPS8/high-WT1/high-MDR1 profile was significantly shorter than in patients with the low-EPS8/low-WT1/low-MDR1 profile or those excluded from either of these groups (P<0.0001). Thus, EPS8, as MDR1 and WT1, may be a clinically valuable biomarker for assessing the outcome of ALL patients.

  17. 78 FR 62948 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-22

    ... LTDA.; Linked To: DEPOSITO POPULAR DE DROGAS S.A.; Linked To: LABORATORIOS KRESSFOR DE COLOMBIA S.A... DROGAS CONDOR LTDA.; Linked To: D'CACHE S.A.; Linked To: LABORATORIOS Y COMERCIALIZADORA DE...

  18. Detection of drug-resistance genes using single bronchoscopy biopsy specimens.

    PubMed

    Trussardi-Regnier, Aurelie; Millot, Jean-Marc; Gorisse, Marie-Claude; Delvincourt, Chantal; Prevost, Alain

    2007-09-01

    Expression of three major resistance genes MDR1, MRP1 and LRP was investigated in small cell lung cancer, non-small cell lung cancer and metastasis. Single biopsies of bronchoscopy from 73 patients were performed to investigate expression of these three resistance genes by reverse transcriptase-polymerase chain reaction. Relations between gene expression and patient age, smoking status, histology, and chemotherapy were evaluated. A more frequent expression of MDR1 (77 versus 66%), MRP1 (91 versus 72%) and LRP (77 versus 63%) genes was detected in the malignant biopsies than in the non-malignant, respectively. In the metastasis biopsies, expression of these genes was markedly increased. No significant difference was observed between specimens before and after chemotherapy. Biopsies from progressing cancer showed higher MDR1, MRP1 and LRP gene expression. In conclusion, these data reveal a major role of MRP1 in intrinsic resistance and the high gene expression of MDR1 and MRP1 in relapsed diseases.

  19. Fitness and Competitive Ability of Botrytis cinerea Isolates with Resistance to Multiple Chemical Classes of Fungicides.

    PubMed

    Chen, S N; Luo, C X; Hu, M J; Schnabel, G

    2016-09-01

    Resistance to multiple chemical classes of fungicides in Botrytis cinerea isolates from eastern United States strawberry fields is common and strategies to control them are needed. In this study, we compared fitness and competitive ability of eight sensitive isolates (S), eight isolates resistant to five or six chemical classes of fungicides but not to phenylpyrroles (5CCR), and eight isolates resistant to six or seven chemical classes including phenylpyrroles (6CCR/MDR1h). The latter included the MDR1h phenotype due to overexpression of atrB based on Δ497V/L in mrr1. The 6CCR/MDR1h isolates grew more slowly at 4°C on potato dextrose agar, and both 5CCR and 6CCR/MDR1h isolates were hypersensitive to osmotic stress compared with S isolates. In contrast, no differences were found in oxidative sensitivity, aggressiveness, and spore production in vivo, and sclerotia production and viability in vitro. In competition experiments, the 5CCR and 6CCR/MDR1h isolates were both outcompeted by S isolates and 6CCR/MDR1h isolates were outcompeted by 5CCR isolates in the absence of fungicide pressure. Under selective pressure of a fludioxonil/pyraclostrobin rotation, the 6CCR/MDR1h isolates dominated after coinoculation with 5CCR and S isolates. The competitive disadvantage of 5CCR and especially 6CCR/MDR1h isolates suggest that, in the absence of fungicide selection pressure, S isolates may reduce inoculum potential of multifungicide-resistant isolates under field conditions.

  20. 78 FR 28701 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-15

    ...) (``IEEPA''), issued Executive Order 12978 (60 FR 54579, October 24, 1995) (the ``Order''). In the Order... Nicolas), c/o DEPOSITO POPULAR DE DROGAS S.A., Cali, Colombia; c/ o DISTRIBUIDORA DE DROGAS CONDOR LTDA... (Colombia) (individual) . 6. FERNANDEZ LUNA, Tiberio, c/o DISTRIBUIDORA DE DROGAS CONDOR S.A.,...

  1. Impact of genetic deficiencies of P-glycoprotein and breast cancer resistance protein on pharmacokinetics of aripiprazole and dehydroaripiprazole.

    PubMed

    Nagasaka, Yasuhisa; Sano, Tomokazu; Oda, Kazuo; Kawamura, Akio; Usui, Takashi

    2014-10-01

    1. We investigated how deficiencies in P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) affect the pharmacokinetics of atypical antipsychotics aripiprazole and its active metabolite (dehydroaripiprazole) using normal Friend leukemia virus strain B (FVB) mice, BCRP knockout (Bcrp[-/-]) mice, and P-gp and BCRP triple knockout (Mdr1a/1b[-/-]Bcrp[-/-]) mice. 2. While plasma concentrations of aripiprazole and dehydroaripiprazole after oral administration were slightly higher in both Bcrp(-/-) and Mdr1a/1b(-/-)/Bcrp(-/-) mice than in normal FVB mice, the difference was not marked. The increase in absolute bioavailability (F) compared with normal mice (approximately 1.3-fold increase) was comparable between Bcrp(-/-) and Mdr1a/1b(-/-)/Bcrp(-/-) mice. This finding suggests that BCRP may be involved in the intestinal absorption of aripiprazole in mice, albeit with minimal contribution to absorption at best. 3. In contrast, the brain-to-plasma concentration ratio (Kp,brain) for aripiprazole and dehydroaripiprazole after oral administration was significantly higher in Mdr1a/1b(-/-)/Bcrp(-/-) mice than in normal mice, whereas Bcrp(-/-) mice exhibited Kp,brain values similar to those in normal mice. In addition, the Kp,brain values in Mdr1a/1b(-/-)/Bcrp(-/-) mice were not drastically different from those previously reported in Mdr1a/1b(-/-) mice, suggesting that brain penetration of aripiprazole and dehydroaripiprazole can be affected by P-gp, but with little synergistic effect of BCRP.

  2. Targeting MDR in breast and lung cancer: discriminating its potential importance from the failure of drug resistance reversal studies.

    PubMed

    Amiri-Kordestani, Laleh; Basseville, Agnes; Kurdziel, Karen; Fojo, Antonio Tito; Bates, Susan E

    2012-01-01

    This special issue of Drug Resistance Updates is dedicated to multidrug resistance protein 1 (MDR-1), 35 years after its discovery. While enormous progress has been made and our understanding of drug resistance has become more sophisticated and nuanced, after 35 years the role of MDR-1 in clinical oncology remains a work in progress. Despite clear in vitro evidence that P-glycoprotein (Pgp), encoded by MDR-1, is able to dramatically reduce drug concentrations in cultured cells, and that drug accumulation can be increased by small molecule inhibitors, clinical trials testing this paradigm have mostly failed. Some have argued that it is no longer worthy of study. However, repeated analyses have demonstrated MDR-1 expression in a tumor is a poor prognostic indicator leading some to conclude MDR-1 is a marker of a more aggressive phenotype, rather than a mechanism of drug resistance. In this review we will re-evaluate the MDR-1 story in light of our new understanding of molecular targeted therapy, using breast and lung cancer as examples. In the end we will reconcile the data available and the knowledge gained in support of a thesis that we understand far more than we realize, and that we can use this knowledge to improve future therapies.

  3. P-glycoprotein inhibition by the agricultural pesticide propiconazole and its hydroxylated metabolites: Implications for pesticide-drug interactions.

    PubMed

    Mazur, Christopher S; Marchitti, Satori A; Zastre, Jason

    2015-01-01

    The human efflux transporter P-glycoprotein (P-gp, MDR1) functions as an important cellular defense system against a variety of xenobiotics; however, little information exists on whether environmental chemicals interact with P-gp. Conazoles provide a unique challenge to exposure assessment because of their use as both pesticides and drugs. Propiconazole is an agricultural pesticide undergoing evaluation by the U.S. Environmental Protection Agency's Endocrine Disruptor Screening Program. In this study, the P-gp interaction of propiconazole and its hydroxylated metabolites were evaluated using MDR1-expressing membrane vesicles and NIH-3T3/MDR1 cells. Membrane vesicle assays demonstrated propiconazole (IC50,122.9μM) and its metabolites (IC50s, 350.8μM, 366.4μM, and 456.3μM) inhibited P-gp efflux of a probe substrate, with propiconazole demonstrating the strongest interaction. P-gp mediated transport of propiconazole in MDR1-expressed vesicles was not detected indicating propiconazole interacts with P-gp as an inhibitor rather than a substrate. In NIH-3T3/MDR1 cells, propiconazole (1 and 10μM) led to decreased cellular resistance (chemosensitization) to paclitaxel, a chemotherapeutic drug and known MDR1 substrate. Collectively, these results have pharmacokinetic and risk assessment implications as P-gp interaction may influence pesticide toxicity and the potential for pesticide-drug interactions.

  4. Turning Awareness into Action: What Your Community Can Do about Drug Use in America = De La Toma de Conciencia a la Accion: Que Puede Hacer la Comunidad Respecto al Consumo de Drogas en America.

    ERIC Educational Resources Information Center

    Alcohol, Drug Abuse, and Mental Health Administration (DHHS/PHS), Rockville, MD. Office for Substance Abuse Prevention.

    This booklet gives examples of successful community drug abuse prevention programs, as well as guidelines for finding out more about a community's prevention needs and taking action. The first section discusses taking action against drug abuse. It presents examples which illustrate the different approaches communities have taken. Ten steps to help…

  5. Positive Prevention: Successful Approaches To Preventing Youthful Drug and Alcohol Use [and] La Prevencion Positiva: Metodos que han tenido exito en la prevencion del uso de drogas y alcohol entre la juventud.

    ERIC Educational Resources Information Center

    American Association of School Administrators, Arlington, VA.

    The United States has the highest rate of youthful drug abuse of any industrialized country in the world. There is a growing awareness that drug and alcohol use are closely connected to other problems such as teenage suicide, adolescent pregnancy, traffic fatalities, juvenile delinquency, poor school performance, runaways, and dropouts. Youthful…

  6. P-glycoprotein is a major determinant of norbuprenorphine brain exposure and antinociception.

    PubMed

    Brown, Sarah M; Campbell, Scott D; Crafford, Amanda; Regina, Karen J; Holtzman, Michael J; Kharasch, Evan D

    2012-10-01

    Norbuprenorphine is a major metabolite of buprenorphine and potent agonist of μ, δ, and κ opioid receptors. Compared with buprenorphine, norbuprenorphine causes minimal antinociception but greater respiratory depression. It is unknown whether the limited antinociception is caused by low efficacy or limited brain exposure. Norbuprenorphine is an in vitro substrate of the efflux transporter P-glycoprotein (Mdr1), but the role of P-glycoprotein in norbuprenorphine transport in vivo is unknown. This investigation tested the hypothesis that limited norbuprenorphine antinociception results from P-glycoprotein-mediated efflux and limited brain access. Human P-glycoprotein-mediated transport in vitro of buprenorphine, norbuprenorphine, and their respective glucuronide conjugates was assessed by using transfected cells. P-glycoprotein-mediated norbuprenorphine transport and consequences in vivo were assessed by using mdr1a(+/+) and mdr1a(-/-) mice. Antinociception was determined by hot-water tail-flick assay, and respiratory effects were determined by unrestrained whole-body plethysmography. Brain and plasma norbuprenorphine and norbuprenorphine-3-glucuronide were quantified by mass spectrometry. In vitro, the net P-glycoprotein-mediated efflux ratio for norbuprenorphine was nine, indicating significant efflux. In contrast, the efflux ratio for buprenorphine and the two glucuronide conjugates was unity, indicating absent transport. The norbuprenorphine brain/plasma concentration ratio was significantly greater in mdr1a(-/-) than mdr1a(+/+) mice. The magnitude and duration of norbuprenorphine antinociception were significantly increased in mdr1a(-/-) compared with mdr1a(+/+) mice, whereas the reduction in respiratory rate was similar. Results show that norbuprenorphine is an in vitro and in vivo substrate of P-glycoprotein. P-glycoprotein-mediated efflux influences brain access and antinociceptive, but not the respiratory, effects of norbuprenorphine. PMID:22739506

  7. P-Glycoprotein Is a Major Determinant of Norbuprenorphine Brain Exposure and Antinociception

    PubMed Central

    Brown, Sarah M.; Campbell, Scott D.; Crafford, Amanda; Regina, Karen J.; Holtzman, Michael J.

    2012-01-01

    Norbuprenorphine is a major metabolite of buprenorphine and potent agonist of μ, δ, and κ opioid receptors. Compared with buprenorphine, norbuprenorphine causes minimal antinociception but greater respiratory depression. It is unknown whether the limited antinociception is caused by low efficacy or limited brain exposure. Norbuprenorphine is an in vitro substrate of the efflux transporter P-glycoprotein (Mdr1), but the role of P-glycoprotein in norbuprenorphine transport in vivo is unknown. This investigation tested the hypothesis that limited norbuprenorphine antinociception results from P-glycoprotein-mediated efflux and limited brain access. Human P-glycoprotein-mediated transport in vitro of buprenorphine, norbuprenorphine, and their respective glucuronide conjugates was assessed by using transfected cells. P-glycoprotein-mediated norbuprenorphine transport and consequences in vivo were assessed by using mdr1a(+/+) and mdr1a(−/−) mice. Antinociception was determined by hot-water tail-flick assay, and respiratory effects were determined by unrestrained whole-body plethysmography. Brain and plasma norbuprenorphine and norbuprenorphine-3-glucuronide were quantified by mass spectrometry. In vitro, the net P-glycoprotein-mediated efflux ratio for norbuprenorphine was nine, indicating significant efflux. In contrast, the efflux ratio for buprenorphine and the two glucuronide conjugates was unity, indicating absent transport. The norbuprenorphine brain/plasma concentration ratio was significantly greater in mdr1a(−/−) than mdr1a(+/+) mice. The magnitude and duration of norbuprenorphine antinociception were significantly increased in mdr1a(−/−) compared with mdr1a(+/+) mice, whereas the reduction in respiratory rate was similar. Results show that norbuprenorphine is an in vitro and in vivo substrate of P-glycoprotein. P-glycoprotein-mediated efflux influences brain access and antinociceptive, but not the respiratory, effects of norbuprenorphine. PMID

  8. Differential role of P-glycoprotein and breast cancer resistance protein in drug distribution into brain, CSF and peripheral nerve tissues in rats.

    PubMed

    Huang, Liyue; Li, Xingwen; Roberts, Jonathan; Janosky, Brett; Lin, Min-Hwa Jasmine

    2015-01-01

    1. This study was designed to evaluate how the absence of P-glycoprotein (Pgp, Mdr1a), breast cancer-resistance protein (Bcrp, Abcg2) or both affects drug distribution into sciatic nerves, brain and cerebrospinal fluid (CSF) in rats. 2. Pgp substrate (loperamide), BCRP substrates (dantrolene and proprietary compound X) and dual substrates (imatinib and proprietary compound Y) were well distributed into sciatic nerves with comparable nerve to plasma concentration ratios between wild-type and knockout (KO) rats. 3. Brain exposure increased substantially in Mdr1a(-/-) rats for loperamide and in Mdr1a(-/-)/Abcg2(-/-) rats for imatinib and compound Y, but minimally to modestly in Abcg2(-/-) rats for dantrolene and compound X. The deletion of Mdr1a or Abcg2 alone had little effect on brain distribution of compound Y. 4. While CSF to unbound brain concentration ratio remained ≥3 in the KO animals for dantrolene, compounds X and Y, it was reduced to 1 in the Mdr1a(-/-)/Abcg2(-/-) rats for imatinib. 5. The data indicate that Pgp and Bcrp do not play significant roles in drug distribution into peripheral nerve tissues in rats, while working in concert to regulate brain penetration. Our results further support that CSF concentration may not be a good surrogate for unbound brain concentration of efflux substrates.

  9. The genetic basis of fluconazole resistance development in Candida albicans.

    PubMed

    Morschhäuser, Joachim

    2002-07-18

    Infections by the opportunistic fungal pathogen Candida albicans are widely treated with the antifungal agent fluconazole that inhibits the biosynthesis of ergosterol, the major sterol in the fungal plasma membrane. The emergence of fluconazole-resistant C. albicans strains is a significant problem after long-term treatment of recurrent oropharyngeal candidiasis (OPC) in acquired immunodeficiency syndrome (AIDS) patients. Resistance can be caused by alterations in sterol biosynthesis, by mutations in the drug target enzyme, sterol 14alpha-demethylase (14DM), which lower its affinity for fluconazole, by increased expression of the ERG11 gene encoding 14DM, or by overexpression of genes coding for membrane transport proteins of the ABC transporter (CDR1/CDR2) or the major facilitator (MDR1) superfamilies. Different mechanisms are frequently combined to result in a stepwise development of fluconazole resistance over time. The MDR1 gene is not or barely transcribed during growth in vitro in fluconazole-susceptible C. albicans strains, but overexpressed in many fluconazole-resistant clinical isolates, resulting in reduced intracellular fluconazole accumulation. The activation of the gene in resistant isolates is caused by mutations in as yet unknown trans-regulatory factors, and the resulting constitutive high level of MDR1 expression causes resistance to other toxic compounds in addition to fluconazole. Disruption of both alleles of the MDR1 gene in resistant C. albicans isolates abolishes their resistance to these drugs, providing genetic evidence that MDR1 mediates multidrug resistance in C. albicans. PMID:12084466

  10. Inhibition of pregnane X receptor pathway contributes to the cell growth inhibition and apoptosis of anticancer agents in ovarian cancer cells.

    PubMed

    Masuyama, Hisashi; Nakamura, Keiichiro; Nobumoto, Etsuko; Hiramatsu, Yuji

    2016-09-01

    Epithelial ovarian cancer remains the most devastating gynecologic cancer with drug resistance and rapid recurrence. Pregnane X receptor (PXR) is a nuclear receptor that affects drug metabolism/efflux and drug-drug interaction through control of multiple drug resistance 1 (MDR1), which implies a major role in multidrug resistance, and other genes. We examined whether the inhibition of PXR-mediated pathway using siRNA interference and an antagonist for PXR could influence the paclitaxel and cisplatin cytotoxicity in ovarian cancer cells. PXR agonists, phthalate and pregnenolone had significant positive effects on cytochrome P450 (CYP) 3A4 expression and PXR-mediated transcription through the CYP3A4 promoter, whereas MDR1 expression and PXR-mediated transcription though the MDR1 promoter were significantly increased in the presence of paclitaxel or cisplatin. Downregulation of PXR suppressed the augmented MDR1 expression and PXR-mediated transcription by PXR ligands, and significantly enhanced cell growth inhibition and apoptosis in the presence of paclitaxel or cisplatin. Additionally, ketoconazole, a PXR antagonist, suppressed the augmented MDR1 expression and PXR-mediated transactivation by paclitaxel and cisplatin, and enhanced cell growth inhibition and apoptosis in their presence. In conclusion, inhibition of PXR-mediated pathways could be a novel means of augmenting sensitivity, or overcoming resistance to anticancer agents for ovarian cancer. PMID:27572875

  11. Multidrug Resistance–like Genes of Arabidopsis Required for Auxin Transport and Auxin-Mediated Development

    PubMed Central

    Noh, Bosl; Murphy, Angus S.; Spalding, Edgar P.

    2001-01-01

    Arabidopsis possesses several genes related to the multidrug resistance (MDR) genes of animals, one of which, AtMDR1, was shown to be induced by the hormone auxin. Plants having mutations in AtMDR1 or its closest relative, AtPGP1, were isolated by a reverse genetic strategy. Auxin transport activity was greatly impaired in atmdr1 and atmdr1 atpgp1 double mutant plants. Epinastic cotyledons and reduced apical dominance were mutant phenotypes consistent with the disrupted basipetal flow of auxin. The auxin transport inhibitor 1-naphthylphthalamic acid was shown to bind tightly and specifically to AtMDR1 and AtPGP1 proteins. The results indicate that these two MDR-like genes of Arabidopsis encode 1-naphthylphthalamic acid binding proteins that are required for normal auxin distribution and auxin-mediated development. PMID:11701880

  12. Functional expression of murine multidrug resistance in Xenopus laevis oocytes

    SciTech Connect

    Castillo, G.; Vera, J.C.; Rosen, O.M. ); Yang, Chiaping Huang; Horwitz, S.B. )

    1990-06-01

    The development of multidrug resistance (MDR) is associated with the overproduction of a plasma membrane glycoprotein, P glycoprotein. Here the authors report the functional expression of a member of the murine MDR family of proteins and show that Xenopus oocytes injected with RNA encoding the mouse mdr1b P glycoprotein develop a MDR-like phenotype. Immunological analysis indicated that oocytes injected with the mdr1b RNA synthesized a protein with the size and immunological characteristics of the mouse mdr1b P glycoprotein. These oocytes exhibited a decreased accumulation of ({sup 3}H)vinblastine and showed an increased capacity to extrude the drug compared to control oocytes not expressing the P glycoprotein. In addition, competition experiments indicated that verapamil, vincristine, daunomycin, and quinidine, but not colchicine, can overcome the rapid drug efflux conferred by the expression of the mouse P glycoprotein.

  13. Blonanserin, a novel atypical antipsychotic agent not actively transported as substrate by P-glycoprotein.

    PubMed

    Inoue, Tomoko; Osada, Kenichi; Tagawa, Masaaki; Ogawa, Yuriko; Haga, Toshiaki; Sogame, Yoshihisa; Hashizume, Takanori; Watanabe, Takashi; Taguchi, Atsushi; Katsumata, Takashi; Yabuki, Masashi; Yamaguchi, Noboru

    2012-10-01

    Although blonanserin, a novel atypical antipsychotic agent with dopamine D(2)/serotonin 5-HT(2A) antagonistic properties, displays good brain distribution, the mechanism of this distribution has not been clarified. P-glycoprotein [(P-gp) or multidrug resistance protein 1 (MDR1)] is an efflux transporter expressed in the brain and plays an important role in limiting drug entry into the central nervous system (CNS). In particular, P-gp can affect the pharmacokinetics and efficacy of antipsychotics, and exacerbate or soothe their adverse effects. In this study, we conducted in vitro and in vivo experiments to determine whether blonanserin is a P-gp substrate. Risperidone and its active metabolite 9-hydroxyrisperidone, both of which are P-gp substrates, were used as reference drugs. Affinity of blonanserin, risperidone, and 9-hydroxyrisperidone for P-gp was evaluated by in vitro transcellular transport across LLC-PK1, human MDR1 cDNA-transfected LLC-PK1 (LLC-MDR1), and mouse Mdr1a cDNA-transfected LLC-PK1 (LLC-Mdr1a). In addition, pharmacokinetic parameters in the brain and plasma (B/P ratio) of test compounds were measured in mdr1a/1b knockout (KO) and wild-type (WT) mice. The results of in vitro experiments revealed that P-gp does not actively transport blonanserin as a substrate in humans or mice. In addition, blonanserin displayed comparable B/P ratios in KO and WT mice, whereas B/P ratios of risperidone and 9-hydroxyrisperidone differed markedly in these animals. Our results indicate that blonanserin is not a P-gp substrate and therefore its brain distribution is unlikely to be affected by this transporter.

  14. Establishment of optimized MDCK cell lines for reliable efflux transport studies.

    PubMed

    Gartzke, Dominik; Fricker, Gert

    2014-04-01

    Madin-Darby canine kidney (MDCK) cells transfected with human MDR1 gene (MDCK-MDR1) encoding for P-glycoprotein (hPgp, ABCB1) are widely used for transport studies to identify drug candidates as substrates of this efflux protein. Therefore, it is necessary to rely on constant and comparable expression levels of Pgp to avoid false negative or positive results. We generated a cell line with homogenously high and stable expression of hPgp through sorting single clones from a MDCK-MDR1 cell pool using fluorescence-activated cell sorting (FACS). To obtain control cell lines for evaluation of cross-interactions with endogenous canine Pgp (cPgp) wild-type cells were sorted with a low expression pattern of cPgp in comparison with the MDCK-MDR1. Expression of other transporters was also characterized in both cell lines by quantitative real-time PCR and Western blot. Pgp function was investigated applying the Calcein-AM assay as well as bidirectional transport assays using (3) H-Digoxin, (3) H-Vinblastine, and (3) H-Quinidine as substrates. Generated MDCK-MDR1 cell lines showed high expression of hPgp. Control MDCK-WT cells were optimized in showing a comparable expression level of cPgp in comparison with MDCK-MDR1 cell lines. Generated cell lines showed higher and more selective Pgp transport compared with parental cells. Therefore, they provide a significant improvement in the performance of efflux studies yielding more reliable results.

  15. Protein arginine methyltransferase 1 may be involved in pregnane x receptor-activated overexpression of multidrug resistance 1 gene during acquired multidrug resistant

    PubMed Central

    Li, Tingting; Kong, Ah-Ng Tony; Ma, Zhiqiang; Liu, Haiyan; Liu, Pinghua; Xiao, Yu; Jiang, Xuehua; Wang, Ling

    2016-01-01

    Purpose Pregnane x receptor (PXR) - activated overexpression of the multidrug resistance 1 (MDR1) gene is an important way for tumor cells to acquire drug resistance. However, the detailed mechanism still remains unclear. In the present study, we aimed to investigate whether protein arginine methyl transferase 1(PRMT1) is involved in PXR - activated overexpression of MDR1 during acquired multidrug resistant. Experimental Design Arginine methyltransferase inhibitor 1 (AMI-1) was used to pharmacologically block PRMT1 in resistant breast cancer cells (MCF7/adr). The mRNA and protein levels of MDR1 were detected by real-time PCR and western blotting analysis. Immunofluorescence microscopy and co-immunoprecipitation were used to investigate the physical interaction between PXR and PRMT1. Then, 136 candidate compounds were screened for PRMT1 inhibitors. Lastly, luciferase reporter gene and nude mice bearing resistant breast cancer xenografts were adopted to investigate the anti-tumor effect of PRMT1 inhibitors when combined with adriamycin. Results AMI-1 significantly suppressed the expression of MDR1 in MCF7/adr cells and increased cells sensitivity of MCF7/adr to adriamycin. Physical interaction between PRMT1 and PXR exists in MCF7/adr cells, which could be disrupted by AMI-1. Those results suggest that PRMT1 may be involved in PXR-activated overexpression of MDR1 in resistant breast cancer cells, and AMI-1 may suppress MDR1 by disrupting the interaction between PRMT1 and PXR. Then, five compounds including rutin, isoquercitrin, salvianolic acid A, naproxen, and felodipline were identified to be PRMT1 inhibitors. Finally, those PRMT1 inhibitors were observed to significantly decrease MDR1 promoter activity in vitro and enhance the antitumor effect of adriamycin in nude mice that bearing resistant breast cancer xenografts. Conclusions PRMT1 may be an important co-activator of PXR in activating MDR1 gene during acquired resistance, and PRMT1 inhibitor combined with

  16. 77 FR 74918 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-18

    ... Act (50 U.S.C. 1701-1706) (``IEEPA''), issued Executive Order 12978 (60 FR 54579, October 24, 1995...) . 12. GONZALEZ QUINTERO, Melba Patricia, c/o DISTRIBUIDORA DE DROGAS CONDOR S.A., Bogota, Colombia; c/o...) (individual) . 13. IDARRAGA ORTIZ, Jaime, c/o DISTRIBUIDORA DE DROGAS CONDOR LTDA., Bogota, Colombia;...

  17. 75 FR 21153 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-22

    ...) (``IEEPA''), issued Executive Order 12978 (60 FR 54579, October 24, 1995) (the ``Order''). In the Order..., Colombia; c/o DISTRIBUIDORA DE DROGAS CONDOR LTDA., Bogota, Colombia; DOB 5 Feb 1953; Cedula No. 19194691... DROGAS CONDOR S.A., Bogota, Colombia; c/o COOPCREAR, Bogota, Colombia; DOB 2 Dec 1954; Cedula...

  18. 75 FR 54696 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-08

    ...) (``IEEPA''), issued Executive Order 12978 (60 FR 54579, October 24, 1995) (the ``Order''). In the Order..., Colombia; c/o DISTRIBUIDORA DE DROGAS CONDOR LTDA., Bogota, Colombia; DOB 26 Feb 1947; Cedula No. 14938700....A., Bogota, Colombia; c/o DISTRIBUIDORA DE DROGAS CONDOR LTDA., Bogota, Colombia; c/o...

  19. Gray mold populations in german strawberry fields are resistant to multiple fungicides and dominated by a novel clade closely related to Botrytis cinerea.

    PubMed

    Leroch, Michaela; Plesken, Cecilia; Weber, Roland W S; Kauff, Frank; Scalliet, Gabriel; Hahn, Matthias

    2013-01-01

    The gray mold fungus Botrytis cinerea is a major threat to fruit and vegetable production. Strawberry fields usually receive several fungicide treatments against Botrytis per season. Gray mold isolates from several German strawberry-growing regions were analyzed to determine their sensitivity against botryticides. Fungicide resistance was commonly observed, with many isolates possessing resistance to multiple (up to six) fungicides. A stronger variant of the previously described multidrug resistance (MDR) phenotype MDR1, called MDR1h, was found to be widely distributed, conferring increased partial resistance to two important botryticides, cyprodinil and fludioxonil. A 3-bp deletion mutation in a transcription factor-encoding gene, mrr1, was found to be correlated with MDR1h. All MDR1h isolates and the majority of isolates with resistance to multiple fungicides were found to be genetically distinct. Multiple-gene sequencing confirmed that they belong to a novel clade, called Botrytis group S, which is closely related to B. cinerea and the host-specific species B. fabae. Isolates of Botrytis group S genotypes were found to be widespread in all German strawberry-growing regions but almost absent from vineyards. Our data indicate a clear subdivision of gray mold populations, which are differentially distributed according to their host preference and adaptation to chemical treatments.

  20. P-glycoprotein induction by breast milk attenuates intestinal inflammation in experimental necrotizing enterocolitis

    PubMed Central

    Guner, Yigit S.; Franklin, Ashanti L.; Chokshi, Nikunj K.; Castle, Shannon L.; Pontarelli, Elizabeth; Wang, Jin; Wang, Larry; Prasadarao, Nemani V.; Upperman, Jeffrey S.; Grishin, Anatoly V.; Ford, Henri R.

    2014-01-01

    P-glycoprotein (Pgp), a product of the multi-drug resistance gene MDR1a, is a broad specificity efflux ATP cassette transmembrane transporter that is predominantly expressed in epithelial tissues. Because mdr1a−/− mice tend to develop spontaneous colitis in bacteria-dependent manner, Pgp is believed to have a role in protection of the intestinal epithelium from luminal bacteria. Here we demonstrate that levels of Pgp in the small intestine of newborn rodents dramatically increase during breastfeeding, but not during formula feeding (FF). In rats and mice, levels of intestinal Pgp peak on days 3–7 and 1–5 of breastfeeding, respectively. The mdr1a−/− neonatal mice subjected to FF, hypoxia, and hypothermia have significantly higher incidence and pathology, as well as significantly earlier onset of necrotizing enterocolitis (NEC) than congenic wild type mice. Breast-fed mdr1a−/− neonatal mice are also more susceptible to intestinal damage caused by the opportunistic pathogen Cronobacter sakazakii that has been associated with hospital outbreaks of NEC. Breast milk, but not formula, induces Pgp expression in enterocyte cell lines in a dose- and time-dependent manner. High levels of ectopically expressed Pgp protect epithelial cells in vitro from apoptosis induced by C. sakazakii. Taken together, these results show that breast milk-induced expression of Pgp may have a role in the protection of the neonatal intestinal epithelium from injury associated with nascent bacterial colonization. PMID:21788941

  1. A Computational Approach towards the Understanding of Plasmodium falciparum Multidrug Resistance Protein 1

    PubMed Central

    Patel, Saumya K.; Prasanth Kumar, Sivakumar; Highland, Hyacinth N.; Jasrai, Yogesh T.; Pandya, Himanshu A.; Desai, Ketaki R.

    2013-01-01

    The emergence of drug resistance in Plasmodium falciparum tremendously affected the chemotherapy worldwide while the intense distribution of chloroquine-resistant strains in most of the endemic areas added more complications in the treatment of malaria. The situation has even worsened by the lack of molecular mechanism to understand the resistance conferred by Plasmodia species. Recent studies have suggested the association of antimalarial resistance with P. falciparum multidrug resistance protein 1 (PfMDR1), an ATP-binding cassette (ABC) transporter and a homologue of human P-glycoprotein 1 (P-gp1). The present study deals about the development of PfMDR1 computational model and the model of substrate transport across PfMDR1 with insights derived from conformations relative to inward- and outward-facing topologies that switch on/off the transportation system. Comparison of ATP docked positions and its structural motif binding properties were found to be similar among other ATPases, and thereby contributes to NBD domains dimerization, a unique structural agreement noticed in Mus musculus Pgp and Escherichia coli MDR transporter homolog (MsbA). The interaction of leading antimalarials and phytochemicals within the active pocket of both wild-type and mutant-type PfMDR1 demonstrated the mode of binding and provided insights of less binding affinity thereby contributing to parasite's resistance mechanism. PMID:25937947

  2. Intestinal and Blood-Brain Barrier Permeability of Ginkgolides and Bilobalide: In Vitro and In Vivo Approaches

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study intestinal and blood brain barrier (BBB) transport of ginkgolides A, B, C, J and bilobalide, isolated from Ginkgo biloba (Family-Ginkgoaceae), was evaluated in Caco-2 and MDR1-MDCK cell monolayer models. Transepithelial transport was examined for 2 hours in both absorptive and secretor...

  3. Gray Mold Populations in German Strawberry Fields Are Resistant to Multiple Fungicides and Dominated by a Novel Clade Closely Related to Botrytis cinerea

    PubMed Central

    Leroch, Michaela; Plesken, Cecilia; Weber, Roland W. S.; Kauff, Frank; Scalliet, Gabriel

    2013-01-01

    The gray mold fungus Botrytis cinerea is a major threat to fruit and vegetable production. Strawberry fields usually receive several fungicide treatments against Botrytis per season. Gray mold isolates from several German strawberry-growing regions were analyzed to determine their sensitivity against botryticides. Fungicide resistance was commonly observed, with many isolates possessing resistance to multiple (up to six) fungicides. A stronger variant of the previously described multidrug resistance (MDR) phenotype MDR1, called MDR1h, was found to be widely distributed, conferring increased partial resistance to two important botryticides, cyprodinil and fludioxonil. A 3-bp deletion mutation in a transcription factor-encoding gene, mrr1, was found to be correlated with MDR1h. All MDR1h isolates and the majority of isolates with resistance to multiple fungicides were found to be genetically distinct. Multiple-gene sequencing confirmed that they belong to a novel clade, called Botrytis group S, which is closely related to B. cinerea and the host-specific species B. fabae. Isolates of Botrytis group S genotypes were found to be widespread in all German strawberry-growing regions but almost absent from vineyards. Our data indicate a clear subdivision of gray mold populations, which are differentially distributed according to their host preference and adaptation to chemical treatments. PMID:23087030

  4. Effects of natural nuclear factor-kappa B inhibitors on anticancer drug efflux transporter human P-glycoprotein.

    PubMed

    Nabekura, Tomohiro; Hiroi, Takashi; Kawasaki, Tatsuya; Uwai, Yuichi

    2015-03-01

    Drug efflux transporter P-glycoprotein plays an important role in cancer chemotherapy. The nuclear factor-κB (NF-κB) transcription factors play critical roles in development and progression of cancer. In this study, the effects of natural compounds that can inhibit NF-κB activation on the function of P-glycoprotein were investigated using human MDR1 gene-transfected KB/MDR1 cells. The accumulation of daunorubicin or rhodamine 123, fluorescent substrates of P-glycoprotein, in KB/MDR1 cells increased in the presence of caffeic acid phenetyl ester (CAPE), licochalcone A, anacardic acid, celastrol, xanthohumol, magnolol, and honokiol in a concentration-dependent manner. In contrast, lupeol, zerumbone, thymoquinone, emodin, and anethol had no effects. The ATPase activities of P-glycoprotein were stimulated by CAPE, licochalcone A, anacardic acid, celastrol, xanthohumol, magnolol, and honokiol. Tumor necrosis factor (TNF)-α stimulated NF-κB activation was inhibited by CAPE, licochalcone A, anacardic acid, and xanthohumol. KB/MDR1 cells were sensitized to vinblastine cytotoxicity by CAPE, licochalcone A, anacardic acid, xanthohumol, magnolol, and honokiol, showing that these natural NF-κB inhibitors reverse multidrug resistance. These results suggest that natural compounds, such as CAPE, licochalcone A, and anacardic acid, have dual inhibitory effects on the anticancer drug efflux transporter P-glycoprotein and NF-κB activation, and may become useful to enhance the efficacy of cancer chemotherapy.

  5. Single Nucleotide Polymorphisms in Pediatric Idiopathic Nephrotic Syndrome

    PubMed Central

    Suvanto, Maija; Jahnukainen, Timo; Kestilä, Marjo; Jalanko, Hannu

    2016-01-01

    Polymorphic variants in several molecules involved in the glomerular function and drug metabolism have been implicated in the pathophysiology of pediatric idiopathic nephrotic syndrome (INS), but the results remain inconsistent. We analyzed the association of eleven allelic variants in eight genes (angiopoietin-like 4 (ANGPTL4), glypican 5 (GPC5), interleukin-13 (IL-13), macrophage migration inhibitory factor (MIF), neural nitric oxide synthetase (nNOS), multidrug resistance-1 (MDR1), glucocorticoid-induced transcript-1 (GLCCI1), and nuclear receptor subfamily-3 (NR3C1)) in 100 INS patients followed up till adulthood. We genotyped variants using PCR and direct sequencing and evaluated estimated haplotypes of MDR1 variants. The analysis revealed few differences in SNP genotype frequencies between patients and controls, or in clinical parameters among the patients. Genotype distribution of MDR1 SNPs rs1236, rs2677, and rs3435 showed significant (p < 0.05) association with different medication regimes (glucocorticoids only versus glucocorticoids plus additional immunosuppressives). Some marginal association was detected between ANGPTL4, GPC5, GLCCI1, and NR3C1 variants and different medication regimes, number of relapses, and age of onset. Conclusion. While MDR1 variant genotype distribution associated with different medication regimes, the other analyzed gene variants showed only little or marginal clinical relevance in INS. PMID:27247801

  6. A New Endogenous Overexpression System of Multidrug Transporters of Candida albicans Suitable for Structural and Functional Studies

    PubMed Central

    Banerjee, Atanu; Khandelwal, Nitesh K.; Sanglard, Dominique; Prasad, Rajendra

    2016-01-01

    Fungal pathogens have a robust array of multidrug transporters which aid in active expulsion of drugs and xenobiotics to help them evade toxic effects of drugs. Thus, these transporters impose a major impediment to effective chemotherapy. Although the Saccharomyces cerevisiae strain AD1-8u− has catered well to the need of an overexpression system to study drug transport by multidrug transporters of Candida albicans, artifacts associated with a heterologous system could not be excluded. To avoid the issue, we exploited a azole-resistant clinical isolate of C. albicans to develop a new system devoid of three major multidrug transporters (Cdr1p, Cdr2p, and Mdr1p) for the overexpression of multidrug transporters under native hyperactive CDR1 promoter due to gain of function (GOF) mutation in TAC1. The study deals with overexpression and functional characterization of representatives of two major classes of multidrug transporters, Cdr1p and Mdr1p, to prove the functionality of this newly developed endogenous expression system. Expression of native Cdr1 and Mdr1 protein in C. albicans cells was confirmed by confocal microscopy and immunodetection and resulted in increased resistance to the putative substrates as compared to control. The system was further validated by overexpressing a few key mutant variants of Cdr1p and Mdr1p. Together, our data confirms the utility of new endogenous overexpression system which is devoid of artifactual factors as most suited for functional characterization of multidrug transporter proteins of C. albicans. PMID:26973635

  7. Cell differentiation and the multiple drug resistance phenotype in human erythroleukemic cells.

    PubMed

    Carrett-Dias, Michele; Almeida, Leda Karine; Pereira, Juliano Lacava; Almeida, Daniela Volcan; Filgueira, Daza Moraes Vaz Batista; Marins, Luis Fernando; Votto, Ana Paula de Souza; Trindade, Gilma Santos

    2016-03-01

    The gene expression of Oct-4, a transcription factor and hematopoietic stem cell marker, is higher in Lucena lines, which is MDR, and the gene Alox-5 has also been implicated in the differentiation of some cell lines. The aim of this study was to compare the response to PMA-induced differentiation in MDR and non-MDR cells. We observed the differentiation to megakaryocytes in the K562 cell line, which is non-MDR. The expression of Alox-5 and Nanog genes was downregulated and that of Mdr-1 was upregulated in K562 cells. The Lucena cell line contained a higher number of megakaryocytes than the non-MDR, but this number was not altered by PMA, as well as Mdr-1 gene expression. However, Alox-5 expression was downregulated. Alox-5, Mdr-1, Nanog, Oct-4 and Sox-2 basal expression was also evaluated in the K562, Lucena and FEPS (also MDR) cell lines. The transcription factors gene expression was similar in MDR cell lines. The expression of Alox-5 was higher in the non-MDR cell line, while FEPS had the lowest expression of this gene. The opposite pattern was observed for Mdr-1 gene expression. These results suggest that the Alox-5 gene might play a role in the differentiation of these cell lines. PMID:26852002

  8. P-glycoprotein Inhibition by the Agricultural Pesticide Propiconazole and Its Hydroxylated Metabolites: Implications for Pesticide-Drug Interactions.

    EPA Science Inventory

    The human efflux transporter P-glycoprotein (P-gp; MDR1) functions an important cellular defense system against a variety of xenobiotics; however, little information exists on whether environmental chemicals interact with P-gp. Conazoles provide a unique challenge to exposure ass...

  9. P-glycoprotein Inhibition by the Agricultural Pesticide Propiconazole and Its Hydroxylated Metabolites: Implications for Pesticide-Drug Interactions

    EPA Science Inventory

    The human efflux transporter P-glycoprotein (P-gp, MDR1) functions an important cellular defense system against a variety of xenobiotics; however, little information exists on whether environmental chemicals interact with P-gp. Conazoles provide a unique challenge to exposure ass...

  10. Multidrug resistance protein 1 protects the choroid plexus epithelium and contributes to the blood-cerebrospinal fluid barrier

    PubMed Central

    Wijnholds, Jan; de Lange, Elizabeth C.M.; Scheffer, George L.; van den Berg, Dirk-Jan; Mol, Carla A.A.M.; van der Valk, Martin; Schinkel, Alfred H.; Scheper, Rik J.; Breimer, Douwe D.; Borst, Piet

    2000-01-01

    Multidrug resistance protein 1 (MRP1) is a transporter protein that helps to protect normal cells and tumor cells against the influx of certain xenobiotics. We previously showed that Mrp1 protects against cytotoxic drugs at the testis-blood barrier, the oral epithelium, and the kidney urinary collecting duct tubules. Here, we generated Mrp1/Mdr1a/Mdr1b triple-knockout (TKO) mice, and used them together with Mdr1a/Mdr1b double-knockout (DKO) mice to study the contribution of Mrp1 to the tissue distribution and pharmacokinetics of etoposide. We observed increased toxicity in the TKO mice, which accumulated etoposide in brown adipose tissue, colon, salivary gland, heart, and the female urogenital system. Immunohistochemical staining revealed the presence of Mrp1 in the oviduct, uterus, salivary gland, and choroid plexus (CP) epithelium. To explore the transport function of Mrp1 in the CP epithelium, we used TKO and DKO mice cannulated for cerebrospinal fluid (CSF). We show here that the lack of Mrp1 protein causes etoposide levels to increase about 10-fold in the CSF after intravenous administration of the drug. Our results indicate that Mrp1 helps to limit tissue distribution of certain drugs and contributes to the blood-CSF drug-permeability barrier. PMID:10675353

  11. Gray mold populations in german strawberry fields are resistant to multiple fungicides and dominated by a novel clade closely related to Botrytis cinerea.

    PubMed

    Leroch, Michaela; Plesken, Cecilia; Weber, Roland W S; Kauff, Frank; Scalliet, Gabriel; Hahn, Matthias

    2013-01-01

    The gray mold fungus Botrytis cinerea is a major threat to fruit and vegetable production. Strawberry fields usually receive several fungicide treatments against Botrytis per season. Gray mold isolates from several German strawberry-growing regions were analyzed to determine their sensitivity against botryticides. Fungicide resistance was commonly observed, with many isolates possessing resistance to multiple (up to six) fungicides. A stronger variant of the previously described multidrug resistance (MDR) phenotype MDR1, called MDR1h, was found to be widely distributed, conferring increased partial resistance to two important botryticides, cyprodinil and fludioxonil. A 3-bp deletion mutation in a transcription factor-encoding gene, mrr1, was found to be correlated with MDR1h. All MDR1h isolates and the majority of isolates with resistance to multiple fungicides were found to be genetically distinct. Multiple-gene sequencing confirmed that they belong to a novel clade, called Botrytis group S, which is closely related to B. cinerea and the host-specific species B. fabae. Isolates of Botrytis group S genotypes were found to be widespread in all German strawberry-growing regions but almost absent from vineyards. Our data indicate a clear subdivision of gray mold populations, which are differentially distributed according to their host preference and adaptation to chemical treatments. PMID:23087030

  12. Interaction of BDE-47 and its Hydroxylated Metabolite 6-OH-BDE-47 with the Human ABC Efflux Transporters P-gp and BCRP: Considerations for Human Exposure and Risk Assessment

    EPA Science Inventory

    ATP binding cassette (ABC) transporters, including P-glycoprotein (P-gp; also known as MDR1, ABCB1) and breast cancer resistance protein (BCRP; also known as ABCG2), are membrane-bound proteins that mediate the cellular efflux of xenobiotics as an important defense against chemic...

  13. Cloning and regulation of the rat mdr2 gene.

    PubMed Central

    Brown, P C; Thorgeirsson, S S; Silverman, J A

    1993-01-01

    We have cloned the complete cDNA encoding the rat mdr2 gene by a combination of library screening and the polymerase chain reaction. The sequence of rat mdr2 cDNA is highly similar to other members of the mdr gene family but the initiation of transcription, tissue distribution and regulation of expression of rat mdr2 diverge from the other isoforms. Primer extension analysis showed rat mdr2 mRNA to have a major transcription start point at -277 and a minor one at approximately -518. We constructed gene specific probes for rat mdr2 and mdr1b and compared the expression patterns of these two genes. The highest expression of mdr2 mRNA was in the muscle, heart, liver and spleen. Both mdr2 and 1b mRNA levels were elevated in the livers of rats treated with CCl4 or following partial hepatectomies although the time course of induction of each gene differed. Mdr1b increased by 12 to 24 hours while mdr2 did not increase until 48 hours. Treatment of isolated hepatocytes or RC3 cells with cycloheximide did not effect mdr2 mRNA. In contrast, mdr1b expression was increased. These data suggest that rat mdr2, unlike mdr1b, is not regulated by a negative trans-acting protein factor. Images PMID:8103593

  14. Independent Emergence of Resistance to Seven Chemical Classes of Fungicides in Botrytis cinerea.

    PubMed

    Fernández-Ortuño, Dolores; Grabke, Anja; Li, Xingpeng; Schnabel, Guido

    2015-04-01

    Gray mold, caused by the fungal pathogen Botrytis cinerea, is one of the most destructive diseases of small fruit crops and control is largely dependent on the application of fungicides. As part of a region-wide resistance-monitoring program that investigated 1,890 B. cinerea isolates from 189 fields in 10 states of the United States, we identified seven isolates (0.4%) from five locations in four different states with unprecedented resistance to all seven Fungicide Resistance Action Committee (FRAC) codes with single-site modes of action including FRAC 1, 2, 7, 9, 11, 12, and 17 registered in the United States for gray mold control. Resistance to thiophanate-methyl, iprodione, boscalid, pyraclostrobin, and fenhexamid was based on target gene mutations that conferred E198A and F200Y in β-tubulin, I365N/S in Bos1, H272R/Y in SdhB, G143A in Cytb, and T63I and F412S in Erg27. Isolates were grouped into MDR1 and MDR1h phenotypes based on sensitivity to fludioxonil and variations in transcription factor mrr1. MDR1h isolates had a previously described 3-bp deletion at position 497 in mrr1. Expression of ABC transporter atrB was increased in MDR1 isolates but highest in MDR1h isolates. None of the isolates with seven single resistances (SR) had identical nucleotide variations in target genes, indicating that they emerged independently. Multifungicide resistance phenotypes did not exhibit significant fitness penalties for the parameters used in this study, but MDR1h isolates produced more sclerotia at low temperatures and exhibited increased sensitivity to salt stress. In this study we show that current resistance management strategies have not been able to prevent the geographically independent development of resistance to all seven site-specific fungicides currently registered for gray mold control in the United States and document the presence of MDR1h in North America. PMID:25317841

  15. Independent Emergence of Resistance to Seven Chemical Classes of Fungicides in Botrytis cinerea.

    PubMed

    Fernández-Ortuño, Dolores; Grabke, Anja; Li, Xingpeng; Schnabel, Guido

    2015-04-01

    Gray mold, caused by the fungal pathogen Botrytis cinerea, is one of the most destructive diseases of small fruit crops and control is largely dependent on the application of fungicides. As part of a region-wide resistance-monitoring program that investigated 1,890 B. cinerea isolates from 189 fields in 10 states of the United States, we identified seven isolates (0.4%) from five locations in four different states with unprecedented resistance to all seven Fungicide Resistance Action Committee (FRAC) codes with single-site modes of action including FRAC 1, 2, 7, 9, 11, 12, and 17 registered in the United States for gray mold control. Resistance to thiophanate-methyl, iprodione, boscalid, pyraclostrobin, and fenhexamid was based on target gene mutations that conferred E198A and F200Y in β-tubulin, I365N/S in Bos1, H272R/Y in SdhB, G143A in Cytb, and T63I and F412S in Erg27. Isolates were grouped into MDR1 and MDR1h phenotypes based on sensitivity to fludioxonil and variations in transcription factor mrr1. MDR1h isolates had a previously described 3-bp deletion at position 497 in mrr1. Expression of ABC transporter atrB was increased in MDR1 isolates but highest in MDR1h isolates. None of the isolates with seven single resistances (SR) had identical nucleotide variations in target genes, indicating that they emerged independently. Multifungicide resistance phenotypes did not exhibit significant fitness penalties for the parameters used in this study, but MDR1h isolates produced more sclerotia at low temperatures and exhibited increased sensitivity to salt stress. In this study we show that current resistance management strategies have not been able to prevent the geographically independent development of resistance to all seven site-specific fungicides currently registered for gray mold control in the United States and document the presence of MDR1h in North America.

  16. [Reversal of adriamycin resistance by digoxin in human breast cancer cell line MCF-7/adriamycin and its mechanism].

    PubMed

    Li, Bai-He; Yuan, Lei; Shi, Ran-Ran; Wang, Jian-Guo

    2015-12-25

    The aim of this study was to investigate the effects of digoxin on the chemoresistance of human breast cancer cell line MCF-7/adriamycin (ADR) and its underlying mechanism. MCF-7 and MCF-7/ADR cells were designated as control and ADR groups, respectively. MCF-7/ADR cells in ADR + digoxin group received 48 h of digoxin (10 nmol/L) treatment; MCF-7/ADR cells transfected with pLKO.1-shHIF-1α and pLKO.1-shcontrol plasmids were named shHIF-1α and shcontrol groups, respectively. CCK-8 assay was employed to detect the cytotoxic effect of ADR on MCF-7/ADR cells, and IC50 value and resistance index were calculated according to CCK-8. RT-PCR was used to measure the mRNA levels of hypoxia inducible factor-1α (HIF-1α) and multidrug resistance-1 (MDR1). Western blot was used to analyze the protein levels of HIF-1α and MDR1. Flow cytometry was used to determine the apoptosis. The result showed that the resistance index of MCF-7/ADR cells was 115.6, and it was reduced to 47.2 under the action of digoxin (P < 0.05). In comparison with control group, ADR groups showed increased protein and mRNA levels of HIF-1α and MDR1 (P < 0.05). Digoxin reduced the protein levels of HIF-1α and MDR1, as well as the mRNA level of MDR1, but did not affect the mRNA level of HIF-1α. After HIF-1α gene was silenced, the protein levels of HIF-1α and MDR1 were down-regulated (P < 0.05), and the pro-apoptotic effect of ADR on MCF-7/ADR cells was enhanced. Although it was also observed that digoxin promoted cell apoptosis in both shcontrol and shHIF-1α groups, the difference between the two groups was not significant. In conclusion, the results suggest that digoxin may partially reverse the ADR resistance in human breast cancer cell line MCF-7/ADR by means of down-regulating the expression levels of HIF-1α and MDR1 and promoting apoptosis via HIF-1α-independent pathway. PMID:26701637

  17. Clitocine reversal of P-glycoprotein associated multi-drug resistance through down-regulation of transcription factor NF-κB in R-HepG2 cell line.

    PubMed

    Sun, Jianguo; Yeung, Chilam Au; Co, Ngai Na; Tsang, Tsun Yee; Yau, Esmond; Luo, Kewang; Wu, Ping; Wa, Judy Chan Yuet; Fung, Kwok-Pui; Kwok, Tim-Tak; Liu, Feiyan

    2012-01-01

    Multidrug resistance (MDR) is one of the major reasons for failure in cancer chemotherapy and its suppression may increase the efficacy of therapy. The human multidrug resistance 1 (MDR1) gene encodes the plasma membrane P-glycoprotein (P-gp) that pumps various anti-cancer agents out of the cancer cell. R-HepG2 and MES-SA/Dx5 cells are doxorubicin induced P-gp over-expressed MDR sublines of human hepatocellular carcinoma HepG2 cells and human uterine carcinoma MES-SA cells respectively. Herein, we observed that clitocine, a natural compound extracted from Leucopaxillus giganteus, presented similar cytotoxicity in multidrug resistant cell lines compared with their parental cell lines and significantly suppressed the expression of P-gp in R-HepG2 and MES-SA/Dx5 cells. Further study showed that the clitocine increased the sensitivity and intracellular accumulation of doxorubicin in R-HepG2 cells accompanying down-regulated MDR1 mRNA level and promoter activity, indicating the reversal effect of MDR by clitocine. A 5'-serial truncation analysis of the MDR1 promoter defined a region from position -450 to -193 to be critical for clitocine suppression of MDR1. Mutation of a consensus NF-κB binding site in the defined region and overexpression of NF-κB p65 could offset the suppression effect of clitocine on MDR1 promoter. By immunohistochemistry, clitocine was confirmed to suppress the protein levels of both P-gp and NF-κB p65 in R-HepG2 cells and tumors. Clitocine also inhibited the expression of NF-κB p65 in MES-SA/Dx5. More importantly, clitocine could suppress the NF-κB activation even in presence of doxorubicin. Taken together; our results suggested that clitocine could reverse P-gp associated MDR via down-regulation of NF-κB.

  18. ABC- and SLC-Transporters in Murine and Bovine Mammary Epithelium - Effects of Prochloraz

    PubMed Central

    Yagdiran, Yagmur; Oskarsson, Agneta; Knight, Christopher H.; Tallkvist, Jonas

    2016-01-01

    Some chemicals are ligands to efflux transporters which may result in high concentrations in milk. Limited knowledge is available on the influence of maternal exposure to chemicals on the expression and function of transporters in the lactating mammary gland. We determined gene expression of ABC and SLC transporters in murine mammary tissue of different gestation and lactation stages, in murine mammary cells (HC11) featuring resting and secreting phenotypes and in bovine mammary tissue and cells (BME-UV). Effects on transporter expression and function of the imidazole fungicide prochloraz, previously reported to influence BCRP in mammary cells, was investigated on transporter expression and function in the two cell lines. Transporters studied were BCRP, MDR1, MRP1, OATP1A5/OATP1A2, OCTN1 and OCT1. Gene expressions of BCRP and OCT1 in murine mammary glands were increased during gestation and lactation, whereas MDR1, MRP1, OATP1A5 and OCTN1 were decreased, compared to expressions in virgins. All transporters measured in mammary glands of mice were detected in bovine mammary tissue and in HC11 cells, while only MDR1 and MRP1 were detected in BME-UV cells. Prochloraz treatment induced MDR1 gene and protein expression in both differentiated HC11 and BME-UV cells and increased protein function in HC11 cells, resulting in decreased accumulation of the MDR1 substrate digoxin. In conclusion, our results demonstrate that murine (HC11) and bovine (BME-UV) mammary epithelial cells can be applied to characterize expression and function of transporters as well as effects of contaminants on the mammary transporters. An altered expression, induced by a drug or toxic chemical, on any of the transporters expressed in the mammary epithelial cells during lactation may modulate the well-balanced composition of nutrients and/or secretion of contaminants in milk with potential adverse effects on breast-fed infants and dairy consumers. PMID:27028005

  19. ABC- and SLC-Transporters in Murine and Bovine Mammary Epithelium--Effects of Prochloraz.

    PubMed

    Yagdiran, Yagmur; Oskarsson, Agneta; Knight, Christopher H; Tallkvist, Jonas

    2016-01-01

    Some chemicals are ligands to efflux transporters which may result in high concentrations in milk. Limited knowledge is available on the influence of maternal exposure to chemicals on the expression and function of transporters in the lactating mammary gland. We determined gene expression of ABC and SLC transporters in murine mammary tissue of different gestation and lactation stages, in murine mammary cells (HC11) featuring resting and secreting phenotypes and in bovine mammary tissue and cells (BME-UV). Effects on transporter expression and function of the imidazole fungicide prochloraz, previously reported to influence BCRP in mammary cells, was investigated on transporter expression and function in the two cell lines. Transporters studied were BCRP, MDR1, MRP1, OATP1A5/OATP1A2, OCTN1 and OCT1. Gene expressions of BCRP and OCT1 in murine mammary glands were increased during gestation and lactation, whereas MDR1, MRP1, OATP1A5 and OCTN1 were decreased, compared to expressions in virgins. All transporters measured in mammary glands of mice were detected in bovine mammary tissue and in HC11 cells, while only MDR1 and MRP1 were detected in BME-UV cells. Prochloraz treatment induced MDR1 gene and protein expression in both differentiated HC11 and BME-UV cells and increased protein function in HC11 cells, resulting in decreased accumulation of the MDR1 substrate digoxin. In conclusion, our results demonstrate that murine (HC11) and bovine (BME-UV) mammary epithelial cells can be applied to characterize expression and function of transporters as well as effects of contaminants on the mammary transporters. An altered expression, induced by a drug or toxic chemical, on any of the transporters expressed in the mammary epithelial cells during lactation may modulate the well-balanced composition of nutrients and/or secretion of contaminants in milk with potential adverse effects on breast-fed infants and dairy consumers. PMID:27028005

  20. Mitochondria of a human multidrug-resistant hepatocellular carcinoma cell line constitutively express inducible nitric oxide synthase in the inner membrane.

    PubMed

    Fantappiè, Ornella; Sassoli, Chiara; Tani, Alessia; Nosi, Daniele; Marchetti, Serena; Formigli, Lucia; Mazzanti, Roberto

    2015-06-01

    Mitochondria play a crucial role in pathways of stress conditions. They can be transported from one cell to another, bringing their features to the cell where they are transported. It has been shown in cancer cells overexpressing multidrug resistance (MDR) that mitochondria express proteins involved in drug resistance such as P-glycoprotein (P-gp), breast cancer resistant protein and multiple resistance protein-1. The MDR phenotype is associated with the constitutive expression of COX-2 and iNOS, whereas celecoxib, a specific inhibitor of COX-2 activity, reverses drug resistance of MDR cells by releasing cytochrome c from mitochondria. It is possible that COX-2 and iNOS are also expressed in mitochondria of cancer cells overexpressing the MDR phenotype. This study involved experiments using the human HCC PLC/PRF/5 cell line with and without MDR phenotype and melanoma A375 cells that do not express the MDR1 phenotype but they do iNOS. Western blot analysis, confocal immunofluorescence and immune electron microscopy showed that iNOS is localized in mitochondria of MDR1-positive cells, whereas COX-2 is not. Low and moderate concentrations of celecoxib modulate the expression of iNOS and P-gp in mitochondria of MDR cancer cells independently from inhibition of COX-2 activity. However, A375 cells that express iNOS also in mitochondria, were not MDR1 positive. In conclusion, iNOS can be localized in mitochondria of HCC cells overexpressing MDR1 phenotype, however this phenomenon appears independent from the MDR1 phenotype occurrence. The presence of iNOS in mitochondria of human HCC cells phenotype probably concurs to a more aggressive behaviour of cancer cells.

  1. Molecular mechanisms of fluconazole resistance in Candida parapsilosis isolates from a U.S. surveillance system.

    PubMed

    Grossman, Nina T; Pham, Cau D; Cleveland, Angela A; Lockhart, Shawn R

    2015-02-01

    Candida parapsilosis is the second or third most common cause of candidemia in many countries. The Infectious Diseases Society of America recommends fluconazole as the primary therapy for C. parapsilosis candidemia. Although the rate of fluconazole resistance among C. parapsilosis isolates is low in most U.S. institutions, the resistance rate can be as high as 7.5%. This study was designed to assess the mechanisms of fluconazole resistance in 706 incident bloodstream isolates from U.S. hospitals. We sequenced the ERG11 and MRR1 genes of 122 C. parapsilosis isolates with resistant (30 isolates; 4.2%), susceptible dose-dependent (37 isolates; 5.2%), and susceptible (55 isolates) fluconazole MIC values and used real-time PCR of RNA from 17 isolates to investigate the regulation of MDR1. By comparing these isolates to fully fluconazole-susceptible isolates, we detected at least two mechanisms of fluconazole resistance: an amino acid substitution in the 14-α-demethylase gene ERG11 and overexpression of the efflux pump MDR1, possibly due to point mutations in the MRR1 transcription factor that regulates MDR1. The ERG11 single nucleotide polymorphism (SNP) was found in 57% of the fluconazole-resistant isolates and in no susceptible isolates. The MRR1 SNPs were more difficult to characterize, as not all resulted in overexpression of MDR1 and not all MDR1 overexpression was associated with an SNP in MRR1. Further work to characterize the MRR1 SNPs and search for overexpression of other efflux pumps is needed.

  2. Saturable active efflux by p-glycoprotein and breast cancer resistance protein at the blood-brain barrier leads to nonlinear distribution of elacridar to the central nervous system.

    PubMed

    Sane, Ramola; Agarwal, Sagar; Mittapalli, Rajendar K; Elmquist, William F

    2013-04-01

    The study objective was to investigate factors that affect the central nervous system (CNS) distribution of elacridar. Elacridar inhibits transport mediated by P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp) and has been used to study the influence of transporters on brain distribution of chemotherapeutics. Adequate distribution of elacridar across the blood-brain barrier (BBB) and into the brain parenchyma is necessary to target tumor cells in the brain that overexpress transporters and reside behind an intact BBB. We examined the role of P-gp and Bcrp on brain penetration of elacridar using Friend leukemia virus strain B wild-type, Mdr1a/b(-/-), Bcrp1(-/-), and Mdr1a/b(-/-)Bcrp1(-/-) mice. Initially, the mice were administered 2.5 mg/kg of elacridar intravenously, and the plasma and brain concentrations were determined. The brain-to-plasma partition coefficient of elacridar in the wild-type mice was 0.82, as compared with 3.5 in Mdr1a/b(-/-) mice, 6.6 in Bcrp1(-/-) mice, and 15 in Mdr1a/b(-/-)Bcrp1(-/-) mice, indicating that both P-gp and Bcrp limit the brain distribution of elacridar. The four genotypes were then administered increasing doses of elacridar, and the CNS distribution of elacridar was determined. The observed and model predicted maximum brain-to-plasma ratios (Emax) at the highest dose were not significantly different in all genotypes. However, the ED50 was lower for Mdr1a/b(-/-) mice compared with Bcrp1(-/-) mice. These findings correlate with the relative expression of P-gp and Bcrp at the BBB in these mice and demonstrate the quantitative enhancement in elacridar CNS distribution as a function of its dose. Overall, this study provides useful concepts for future applications of elacridar as an adjuvant therapy to improve targeting of chemotherapeutic agents to tumor cells in the brain parenchyma. PMID:23397054

  3. ABC- and SLC-Transporters in Murine and Bovine Mammary Epithelium--Effects of Prochloraz.

    PubMed

    Yagdiran, Yagmur; Oskarsson, Agneta; Knight, Christopher H; Tallkvist, Jonas

    2016-01-01

    Some chemicals are ligands to efflux transporters which may result in high concentrations in milk. Limited knowledge is available on the influence of maternal exposure to chemicals on the expression and function of transporters in the lactating mammary gland. We determined gene expression of ABC and SLC transporters in murine mammary tissue of different gestation and lactation stages, in murine mammary cells (HC11) featuring resting and secreting phenotypes and in bovine mammary tissue and cells (BME-UV). Effects on transporter expression and function of the imidazole fungicide prochloraz, previously reported to influence BCRP in mammary cells, was investigated on transporter expression and function in the two cell lines. Transporters studied were BCRP, MDR1, MRP1, OATP1A5/OATP1A2, OCTN1 and OCT1. Gene expressions of BCRP and OCT1 in murine mammary glands were increased during gestation and lactation, whereas MDR1, MRP1, OATP1A5 and OCTN1 were decreased, compared to expressions in virgins. All transporters measured in mammary glands of mice were detected in bovine mammary tissue and in HC11 cells, while only MDR1 and MRP1 were detected in BME-UV cells. Prochloraz treatment induced MDR1 gene and protein expression in both differentiated HC11 and BME-UV cells and increased protein function in HC11 cells, resulting in decreased accumulation of the MDR1 substrate digoxin. In conclusion, our results demonstrate that murine (HC11) and bovine (BME-UV) mammary epithelial cells can be applied to characterize expression and function of transporters as well as effects of contaminants on the mammary transporters. An altered expression, induced by a drug or toxic chemical, on any of the transporters expressed in the mammary epithelial cells during lactation may modulate the well-balanced composition of nutrients and/or secretion of contaminants in milk with potential adverse effects on breast-fed infants and dairy consumers.

  4. TLR signaling modulates side effects of anticancer therapy in the small intestine

    PubMed Central

    Frank, Magdalena; Hennenberg, Eva Maria; Eyking, Annette; Rünzi, Michael; Gerken, Guido; Scott, Paul; Parkhill, Julian; Walker, Alan W.; Cario, Elke

    2014-01-01

    Intestinal mucositis represents the most common complication of intensive chemotherapy, which has a severe adverse impact on quality of life of cancer patients. However, the precise pathophysiology remains to be clarified and there is so far no successful therapeutic intervention. Here, we investigated the role of innate immunity through TLR signaling in modulating genotoxic chemotherapy-induced small intestinal injury in vitro and in vivo. Genetic deletion of TLR2, but not MD-2, in mice resulted in severe chemotherapy-induced intestinal mucositis in the proximal jejunum with villous atrophy, accumulation of damaged DNA, CD11b+-myeloid cell infiltration and significant gene alterations in xenobiotic metabolism, including a decrease in ABCB1/MDR1 p-glycoprotein (p-gp) expression. Functionally, stimulation of TLR2 induced synthesis and drug efflux activity of ABCB1/MDR1 p-gp in murine and human CD11b+-myeloid cells, thus inhibiting chemotherapy-mediated cytotoxicity. Conversely, TLR2 activation failed to protect small intestinal tissues genetically deficient in MDR1A against DNA-damaging drug-induced apoptosis. Gut microbiota depletion by antibiotics led to increased susceptibility to chemotherapy-induced mucosal injury in wildtype mice, which was suppressed by administration of a TLR2 ligand, preserving ABCB1/MDR1 p-gp expression. Findings were confirmed in a preclinical model of human chemotherapy-induced intestinal mucositis using duodenal biopsies, by demonstrating that TLR2 activation limited the toxic-inflammatory reaction and maintained assembly of the drug transporter p-gp. In conclusion, this study identifies a novel molecular link between innate immunity and xenobiotic metabolism. TLR2 acts as a central regulator of xenobiotic defense via the multidrug transporter ABCB1/MDR1 p-gp. Targeting TLR2 may represent a novel therapeutic approach in chemotherapy-induced intestinal mucositis. PMID:25589072

  5. 76 FR 25408 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-04

    .... 1701-1706) (``IEEPA''), issued Executive Order 12978 (60 FR 54579, October 24, 1995) (the ``Order... (Colombia) (individual) QUINTANA HERNANDEZ, Gonzalo, c/o DISTRIBUIDORA DE DROGAS LA REBAJA BOGOTA...

  6. 75 FR 79445 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant to Executive Order 12978

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-20

    ... Emergency Economic Powers Act (50 U.S.C. 1701-1706) (``IEEPA''), issued Executive Order 12978 (60 FR 54579..., Colombia; c/o RADIO UNIDAS FM S.A., Cali, Colombia; c/o DISTRIBUIDORA DE DROGAS CONDOR LTDA.,...

  7. ABC proteins protect the human body and maintain optimal health.

    PubMed

    Ueda, Kazumitsu

    2011-01-01

    Human MDR1, a multi-drug transporter gene, was isolated as the first of the eukaryote ATP Binding Cassette (ABC) proteins from a multidrug-resistant carcinoma cell line in 1986. To date, over 25 years, many ABC proteins have been found to play important physiological roles by transporting hydrophobic compounds. Defects in their functions cause various diseases, indicating that endogenous hydrophobic compounds, as well as water-soluble compounds, are properly transported by transmembrane proteins. MDR1 transports a large number of structurally unrelated drugs and is involved in their pharmacokinetics, and thus is a key factor in drug interaction. ABCA1, an ABC protein, eliminates excess cholesterol in peripheral cells by generating HDL. Because ABCA1 is a key molecule in cholesterol homeostasis, its function and expression are highly regulated. Eukaryote ABC proteins function on the body surface facing the outside and in organ pathways to adapt to the extracellular environment and protect the body to maintain optimal health.

  8. Aliskiren toxicity in juvenile rats is determined by ontogenic regulation of intestinal P-glycoprotein expression

    SciTech Connect

    Hoffmann, Peter; Beckman, David; McLean, Lee Anne; Yan, Jing-He

    2014-02-15

    Juvenile rat toxicity studies with the direct renin inhibitor aliskiren were initiated to support treatment in the pediatric population. In Study 1, aliskiren was administered orally to juvenile rats at doses of 0, 30, 100 or 300 mg/kg/day with repeated dosing from postpartum day (PPD) 8 to PPD 35/36. In-life, clinical pathology, anatomic pathology, and toxicokinetics evaluations were performed. In Study 2, single oral doses of aliskiren (0, 100 or 300 mg/kg) were given to 14-, 21-, 24-, 28-, 31- or 36-day-old rats; in-life data and toxicokinetics were evaluated. Study 3 was a single dose (3 mg/kg i.v.) pharmacokinetic study in juvenile rats on PPD 8, 14, 21 and 28. In Study 4, naïve rats were used to investigate ontogenic changes of the multidrug-resistant protein 1 (MDR1) and the organic anion transporting polypeptide (OATP) mRNA in several organs. Oral administration of aliskiren at 100 and 300 mg/kg caused unexpected mortality and severe morbidity in 8-day-old rats. Aliskiren plasma and tissue concentrations were increased in rats aged 21 days and younger. Expression of MDR1 and OATP mRNA in the intestine, liver and brain was significantly lower in very young rats. In conclusion, severe toxicity and increased exposure in very young rats after oral administration of aliskiren are considered to be the result of immature drug transporter systems. Immaturity of MDR1 in enterocytes appears to be the most important mechanism responsible for the high exposure. - Highlights: • Aliskiren was orally administered to juvenile rats. • Unexpected severe toxicity and acute mortality occurred in rats aged 8 days. • Toxicity was associated with increased aliskiren plasma and tissue exposure. • Developmental changes of exposure correlated with ontogeny of transporters. • Immaturity of MDR1 in enterocytes causes increased exposure in very young rats.

  9. Effect of aminoguanidine on lipopolysaccharide-induced changes in rat liver transporters and transcription factors.

    PubMed

    Aoki, Kimiko; Nakajima, Miki; Hoshi, Yoshiyuki; Saso, Naomi; Kato, Satoko; Sugiyama, Yuichi; Sato, Hitoshi

    2008-03-01

    To determine the role of nitric oxide (NO) in rat liver transporter regulation, we investigated whether NO mediates lipopolysaccharide (LPS)-induced changes in transporters and their transcription factor expression using aminoguanidine (AG), an inhibitor of induced nitric oxide synthase (iNOS). We confirmed that LPS decreased mRNA levels for Ntcp, Oatp1, Oatp2, Oatp4, Oct1, Mrp2, Mdr1a and increased those for Mdr1b at 16 h after administration. AG attenuated these decreases for Ntcp, Oatp1 and Oatp4 (retinoid X receptor (RXR)alpha- and hepatocyte nuclear factor (HNF)4alpha-dependent genes) and increase for Mdr1b (nuclear factor (NF)-kappaB-dependent gene). Concomitantly, it suppressed LPS-induced NF-kappaB-dependent gene transcription, such as those for proinflammatory cytokines (cytokines; tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6) and iNOS, and also suppressed IL-1beta release from Kupffer cells (KCs) at post-translational levels, but had little effect on the LPS-induced decreases in RXRalpha and HNF4alpha transcriptional activities. These findings indicate that hepatocytes were stimulated directly by LPS, which lead to the activation of NF-kappaB and reduction of RXRalpha and HNF4alpha transcriptional activities as early responses, and indirectly by cytokines and NO released from KCs via activation of NF-kappaB by LPS as delayed responses. We conclude that AG, which suppresses LPS-induced NF-kappaB activation in both hepatocytes and KCs and then the release of cytokines and NO from KCs, attenuates LPS-induced changes of Ntcp, Oatp1, Oatp4 and Mdr1b transcription in hepatocytes. The roles of cytokines and NO could not be distinguished, however. Further in vitro study is needed to clarify the role of NO in transporter regulation. PMID:18310902

  10. The antiepileptic drug mephobarbital is not transported by P-glycoprotein or multidrug resistance protein 1 at the blood-brain barrier: a positron emission tomography study

    PubMed Central

    Mairinger, Severin; Bankstahl, Jens P.; Kuntner, Claudia; Römermann, Kerstin; Bankstahl, Marion; Wanek, Thomas; Stanek, Johann; Löscher, Wolfgang; Müller, Markus; Erker, Thomas; Langer, Oliver

    2013-01-01

    Summary Aim of this study was to determine whether the carbon-11-labelled antiepileptic drug [11C]mephobarbital is a substrate of P-glycoprotein (Pgp) and can be used to assess Pgp function at the blood-brain barrier (BBB) with positron emission tomography (PET). We performed paired PET scans in rats, wild-type (FVB) and Mdr1a/b(−/−) mice, before and after intravenous administration of the Pgp inhibitor tariquidar (15 mg/kg). Brain-to-blood AUC0-60 ratios in rats and brain AUC0-60 values of [11C]mephobarbital in wild-type and Mdr1a/b(−/−) mice were similar in scan 1 and scan 2, respectively, suggesting that in vivo brain distribution of [11C]mephobarbital is not influenced by Pgp efflux. Absence of Pgp transport was confirmed in vitro by performing concentration equilibrium transport assay in cell lines transfected with MDR1 or Mdr1a. PET experiments in wild-type mice, with and without pretreatment with the multidrug resistance protein (MRP) inhibitor MK571 (20 mg/kg), and in Mrp1(−/−) mice suggested that [11C]mephobarbital is also not transported by MRPs at the murine BBB, which was also supported by in vitro transport experiments using human MRP1-transfected cells. Our results are surprising as phenobarbital, the N-desmethyl derivative of mephobarbital, has been shown to be a substrate of Pgp, which suggests that N-methylation abolishes Pgp affinity of barbiturates. PMID:22342565

  11. Synthesis and in vivo evaluation of the putative breast cancer resistance protein inhibitor [11C]methyl 4-((4-(2-(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolin-2-yl)ethyl)phenyl)amino-carbonyl)-2-(quinoline-2-carbonylamino)benzoate

    PubMed Central

    Mairinger, Severin; Langer, Oliver; Kuntner, Claudia; Wanek, Thomas; Bankstahl, Jens P.; Bankstahl, Marion; Stanek, Johann; Dörner, Bernd; Bauer, Florian; Baumgartner, Christoph; Löscher, Wolfgang; Erker, Thomas; Müller, Markus

    2013-01-01

    Introduction The multidrug efflux transporter breast cancer resistance protein (BCRP) is highly expressed in the blood-brain barrier (BBB), where it limits brain entry of a broad range of endogenous and exogenous substrates. Methyl 4-((4-(2-(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinolin-2-yl)ethyl)phenyl)amino-carbonyl)-2-(quinoline-2-carbonylamino)benzoate (1) is a recently discovered BCRP-selective inhibitor, which is structurally derived from the potent P-glycoprotein (P-gp) inhibitor tariquidar. The aim of this study was to develop a new PET tracer based on 1 to map BCRP expression levels in vivo. Methods 1 was labelled with 11C in its methyl ester function by reaction of the corresponding carboxylic acid 2 with [11C]methyl triflate. PET imaging of [11C]-1 was performed in wild-type, Mdr1a/b(−/−), Bcrp1(−/−) and Mdr1a/b(−/−)Bcrp1(−/−) mice (n=3 per mouse type) and radiotracer metabolism was assessed in plasma and brain. Results Brain-to-plasma ratios of unchanged [11C]-1 were 4.8- and 10.3-fold higher in Mdr1a/b(−/−) and in Mdr1a/b(−/−)Bcrp1(−/−) mice, respectively, as compared to wild-type animals, but only modestly increased in Bcrp1(−/−) mice. [11C]-1 was rapidly metabolized in vivo giving rise to a polar radiometabolite which was taken up into brain tissue. Conclusion Our data suggest that [11C]-1 preferably interacts with P-gp rather than BCRP at the murine BBB which questions its reported in vitro BCRP selectivity. Consequently, [11C]-1 appears to be unsuitable as a PET tracer to map cerebral BCRP expression. PMID:20610168

  12. Effect of FosPeg® mediated photoactivation on P-gp/ABCB1 protein expression in human nasopharyngeal carcinoma cells.

    PubMed

    Wu, R W K; Chu, E S M; Huang, Z; Xu, C S; Ip, C W; Yow, C M N

    2015-07-01

    Multidrug resistance (MDR) refers to the ability of cancer cells to develop cross resistance to a range of anticancer drugs which are structurally and functionally unrelated. P-glycoprotein (P-gp) is the best studied MDR phenotype in photodynamic therapy (PDT) treated cells. Our pervious study demonstrated that FosPeg® mediated PDT is effective to NPC cell line models. In this in vitro study, the expression of MDR1 gene and its product P-gp in undifferentiated, poorly differentiated and well differentiated human nasopharyngeal carcinoma (NPC) cells were investigated. The influence of P-gp efflux activities on photosensitizer FosPeg® was also examined. Regardless of the differentiation status, PDT tested NPC cell lines all expressed P-gp protein. Results indicated that FosPeg® photoactivation could heighten the expression of MDR1 gene and P-gp transporter protein in a dose dependent manner. Up to 2-fold increase of P-gp protein expression were seen in NPC cells after FosPeg® mediated PDT. Interestingly, our finding demonstrated that FosPeg® mediated PDT efficiency is independent to the MDR1 gene and P-gp protein expression in NPC cells. FosPeg® itself is not the substrate of P-gp transporter protein and no efflux of FosPeg® were observed in NPC cells. Therefore, the PDT efficiency would not be affected even though FosPeg® mediated PDT could induce MDR1 gene and P-gp protein expression in NPC cells. FosPeg® mediated PDT could be a potential therapeutic approach for MDR cancer patients. PMID:25900553

  13. Ursodeoxycholic acid inhibits overexpression of P-glycoprotein induced by doxorubicin in HepG2 cells.

    PubMed

    Komori, Yuki; Arisawa, Sakiko; Takai, Miho; Yokoyama, Kunihiro; Honda, Minako; Hayashi, Kazuhiko; Ishigami, Masatoshi; Katano, Yoshiaki; Goto, Hidemi; Ueyama, Jun; Ishikawa, Tetsuya; Wakusawa, Shinya

    2014-02-01

    The hepatoprotective action of ursodeoxycholic acid (UDCA) was previously suggested to be partially dependent on its antioxidative effect. Doxorubicin (DOX) and reactive oxygen species have also been implicated in the overexpression of P-glycoprotein (P-gp), which is encoded by the MDR1 gene and causes antitumor multidrug resistance. In the present study, we assessed the effects of UDCA on the expression of MDR1 mRNA, P-gp, and intracellular reactive oxygen species levels in DOX-treated HepG2 cells and compared them to those of other bile acids. DOX-induced increases in reactive oxygen species levels and the expression of MDR1 mRNA were inhibited by N-acetylcysteine, an antioxidant, and the DOX-induced increase in reactive oxygen species levels and DOX-induced overexpression of MDR1 mRNA and P-gp were inhibited by UDCA. Cells treated with UDCA showed improved rhodamine 123 uptake, which was decreased in cells treated with DOX alone. Moreover, cells exposed to DOX for 24h combined with UDCA accumulated more DOX than that of cells treated with DOX alone. Thus, UDCA may have inhibited the overexpression of P-gp by suppressing DOX-induced reactive oxygen species production. Chenodeoxycholic acid (CDCA) also exhibited these effects, whereas deoxycholic acid and litocholic acid were ineffective. In conclusion, UDCA and CDCA had an inhibitory effect on the induction of P-gp expression and reactive oxygen species by DOX in HepG2 cells. The administration of UDCA may be beneficial due to its ability to prevent the overexpression of reactive oxygen species and acquisition of multidrug resistance in hepatocellular carcinoma cells.

  14. Inflammatory Regulation of ATP Binding Cassette Efflux Transporter Expression and Function in Microglia

    PubMed Central

    Gibson, Christopher J.; Hossain, Muhammad M.; Richardson, Jason R.

    2012-01-01

    ATP-binding cassette (ABC) efflux transporters, including multidrug resistance protein 1 (Mdr1), breast cancer resistance protein (Bcrp), and multidrug resistance-associated proteins (Mrps) extrude chemicals from the brain. Although ABC transporters are critical for blood-brain barrier integrity, less attention has been placed on the regulation of these proteins in brain parenchymal cells such as microglia. Prior studies demonstrate that inflammation after lipopolysaccharide (LPS) treatment alters transporter expression in the livers of mice. Here, we sought to determine the effects of inflammation on the expression and function of transporters in microglia. To test this, the expression and function of ABC efflux transport proteins were quantified in mouse BV-2 microglial cells in response to activation with LPS. Intracellular retention of fluorescent rhodamine 123, Hoechst 33342, and calcein acetoxymethyl ester was increased in LPS-treated microglia, suggesting that the functions of Mdr1, Bcrp, and Mrps were decreased, respectively. LPS reduced Mdr1, Bcrp, and Mrp4 mRNA and protein expression between 40 and 70%. Conversely, LPS increased expression of Mrp1 and Mrp5 mRNA and protein. Immunofluorescent staining confirmed reduced Bcrp and Mrp4 and elevated Mrp1 and Mrp5 protein in activated microglia. Pharmacological inhibition of nuclear factor κB (NF-κB) transcriptional signaling attenuated down-regulation of Mdr1a mRNA and potentiated up-regulation of Mrp5 mRNA in LPS-treated cells. Together, these data suggest that LPS stimulates microglia and impairs efflux of prototypical ABC transporter substrates by altering mRNA and protein expression, in part through NF-κB signaling. Decreased transporter efflux function in microglia may lead to the retention of toxic chemicals and aberrant cell-cell communication during neuroinflammation. PMID:22942241

  15. [Cytological Study in vitro on Co-delivery of siRNA and Paclitaxel within Solid Lipid Nanoparticles to Overcome Multidrug Resistance in Tumors].

    PubMed

    Huang, Rui; Yao, Xinyu; Chen, Yuan; Sun, Xun; Lin, Yunzhu

    2016-02-01

    Multidrug resistance (MDR) remains the major obstacle to the success of clinical cancer chemotherapy. P-glycoprotein (P-gp), encoded by the MDR1, is an important part with complex mechanisms associated with the MDR. In order to overcome the MDR of tumors, we in the present experimental design incorporated small interfering RNA (siRNA) targeting MDR1 gene and anticancer drug paclitaxel (PTX) into the solid lipid nanoparticles (SLNs) to achieve the combinational therapeutic effects of genetherapy and chemotherapy. In this study, siRNA-PTX-SLNs were successfully prepared. The cytotoxicity of blank SLNs and siRNA-PTX-SLNs in MCF-7 cells and MCF-7/ADR cells were detected by MTT; and the uptake efficiency of PTX in MCF-7/ADR cells were detected via HPLC method; quantitative real-time PCR and flow cytometry were performed to investigate the silencing effect of siRNA-PTX- SLNs on MDR1 gene in MCF-7/ADR cells. The results showed that PTX loaded SLNs could significantly inhibit the growth of tumor cells, and more importantly, the MDR tumor cells treated with siRNA-PTX-SLNs showed the lowest viability. HPLC study showed that SLNs could enhance the cellular uptake for PTX. Meanwhile, siRNA delivered by SLNs significantly decreased the P-gp expression in MDR tumor cells, thus increased the cellular accumulation of rhodamine123 as a P-gp substrate. In conclusion, the MDR1 gene could be silenced by siRNA-PTX-SLNs, which could promote the growth inhibition efficiency of PTX on tumor cells, leading to synergetic effect on MDR tumor therapy. PMID:27382749

  16. A novel role for BDNF-TrkB in the regulation of chemotherapy resistance in head and neck squamous cell carcinoma.

    PubMed

    Lee, Junegoo; Jiffar, Tilahun; Kupferman, Michael E

    2012-01-01

    Mechanisms of resistance for HNSCC to cisplatin (CDDP), the foundational chemotherapeutic agent in the treatment of this disease, remain poorly understood. We previously demonstrated that cisplatin resistance (CR) can be overcome by targeting Trk receptor. In the current study, we explored the potential mechanistic role of the BDNF-TrkB signaling system in the development of CDDP resistance in HNSCC. Utilizing an in vitro system of acquired CR, we confirmed a substantial up-regulation of both BDNF and TrkB at the protein and mRNA levels in CR cells, suggesting an autocrine pathway dysregulation in this system. Exogenous BDNF stimulation led to an enhanced expression of the drug-resistance and anti-apoptotic proteins MDR1 and XiAP, respectively, in a dose-dependently manner, demonstrating a key role for BDNF-TrkB signaling in modulating the response to cytotoxic agents. In addition, modulation of TrkB expression induced an enhanced sensitivity of cells to CDDP in HNSCC. Moreover, genetic suppression of TrkB resulted in changes in expression of Bim, XiAP, and MDR1 contributing to HNSCC survival. To elucidate intracellular signaling pathways responsible for mechanisms underlying BDNF/TrkB induced CDDP-resistance, we analyzed expression levels of these molecules following inhibition of Akt. Inhibition of Akt eliminated BDNF effect on MDR1 and Bim expression in OSC-19P cells as well as modulated expressions of MDR1, Bim, and XiAP in OSC-19CR cells. These results suggest BDNF/TrkB system plays critical roles in CDDP-resistance development by utilizing Akt-dependent signaling pathways.

  17. Eletriptan metabolism by human hepatic CYP450 enzymes and transport by human P-glycoprotein.

    PubMed

    Evans, David C; O'Connor, Desmond; Lake, Brian G; Evers, Raymond; Allen, Christopher; Hargreaves, Richard

    2003-07-01

    "Reaction phenotyping" studies were performed with eletriptan (ETT) to determine its propensity to interact with coadministered medications. Its ability to serve as a substrate for human P-glycoprotein (P-gp) was also investigated since a central mechanism of action has been proposed for this "triptan" class of drug. In studies with a characterized bank of human liver microsome preparations, a good correlation (r2 = 0.932) was obtained between formation of N-desmethyl eletriptan (DETT) and CYP3A4-catalyzed testosterone 6 beta-hydroxylation. DETT was selected to be monitored in our studies since it represents a significant ETT metabolite in humans, circulating at concentrations 10 to 20% of those observed for parent drug. ETT was metabolized to DETT by recombinant CYP2D6 (rCYP2D6) and rCYP3A4, and to a lesser extent by rCYP2C9 and rCYP2C19. The metabolism of ETT to DETT in human liver microsomes was markedly inhibited by troleandomycin, erythromycin, miconazole, and an inhibitory antibody to CYP3A4, but not by inhibitors of other major P450 enzymes. ETT had little inhibitory effect on any of the P450 enzymes investigated. ETT was determined to be a good substrate for human P-gp in vitro. In bidirectional transport studies across LLC-MDR1 and LLC-Mdr1a cell monolayers, ETT had a BA/AB transport ratio in the range 9 to 11. This finding had significance in vivo since brain exposure to ETT was reduced 40-fold in Mdr1a+/+ relative to Mdr1a-/- mice. ETT metabolism to DETT is therefore catalyzed primarily by CYP3A4, and plasma concentrations are expected to be increased when coadministered with inhibitors of CYP3A4 and P-gp activity. PMID:12814962

  18. Piperine activates human pregnane X receptor to induce the expression of cytochrome P450 3A4 and multidrug resistance protein 1

    SciTech Connect

    Wang, Yue-Ming; Lin, Wenwei; Chai, Sergio C.; Wu, Jing; Ong, Su Sien; Schuetz, Erin G.; Chen, Taosheng

    2013-10-01

    Activation of the pregnane X receptor (PXR) and subsequently its target genes, including those encoding drug transporters and metabolizing enzymes, while playing substantial roles in xenobiotic detoxification, might cause undesired drug-drug interactions. Recently, an increased awareness has been given to dietary components for potential induction of diet–drug interactions through activation of PXR. Here, we studied, whether piperine (PIP), a major component extracted from the widely-used daily spice black pepper, could induce PXR-mediated expression of cytochrome P450 3A4 (CYP3A4) and multidrug resistance protein 1 (MDR1). Our results showed that PIP activated human PXR (hPXR)-mediated CYP3A4 and MDR1 expression in human hepatocytes, intestine cells, and a mouse model; PIP activated hPXR by recruiting its coactivator SRC-1 in both cellular and cell-free systems; PIP bound to the hPXR ligand binding domain in a competitive ligand binding assay in vitro. The dichotomous effects of PIP on induction of CYP3A4 and MDR1 expression observed here and inhibition of their activity reported elsewhere challenges the potential use of PIP as a bioavailability enhancer and suggests that caution should be taken in PIP consumption during drug treatment in patients, particularly those who favor daily pepper spice or rely on certain pepper remedies. - Highlights: • Piperine induces PXR-mediated CYP3A4 and MDR1 expression. • Piperine activates PXR by binding to PXR and recruiting coactivator SRC-1. • Piperine induces PXR activation in vivo. • Caution should be taken in piperine consumption during drug treatment.

  19. Multifunctional QD-based co-delivery of siRNA and doxorubicin to HeLa cells for reversal of multidrug resistance and real-time tracking.

    PubMed

    Li, Jin-Ming; Wang, Yuan-Yuan; Zhao, Mei-Xia; Tan, Cai-Ping; Li, Yi-Qun; Le, Xue-Yi; Ji, Liang-Nian; Mao, Zong-Wan

    2012-03-01

    Co-delivery of siRNA and chemotherapeutic agents has been developed to combat multidrug resistance in cancer therapy. Recently, we developed a series of quantum dots (QDs) functionalized by β-cyclodextrin (β-CD) coupled to amino acids, some of which can be used to facilitate the delivery of siRNA. In this study, two CdSe/ZnSe QDs modified with β-CD coupled to L-Arg or L-His were used to simultaneously deliver doxorubicin (Dox) and siRNA targeting the MDR1 gene to reverse the multidrug resistance of HeLa cells. In this co-delivery system, Dox was firstly encapsulated into the hydrophobic cavities of β-CD, resulting in bypass of P-glycoprotein (P-gp)-mediated drug efflux. After complex formation of the mdr1 siRNA with Dox-loaded QDs via electrostatic interaction, significant down-regulation of mdr1 mRNA levels and P-gp expression was achieved as shown by RT-PCR and Western blotting experiments, respectively. The number of apoptotic HeLa cells after treatment with the complexes substantially exceeded the number of apoptotic cells induced by free Dox only. The intrinsic fluorescence of the QDs provided an approach to track the system by laser confocal microscopy. These multifunctional QDs are promising vehicles for the co-delivery of nucleic acids and chemotherapeutics and for real-time tracking of treatment.

  20. CRISPR-Cas9-modified pfmdr1 protects Plasmodium falciparum asexual blood stages and gametocytes against a class of piperazine-containing compounds but potentiates artemisinin-based combination therapy partner drugs.

    PubMed

    Ng, Caroline L; Siciliano, Giulia; Lee, Marcus C S; de Almeida, Mariana J; Corey, Victoria C; Bopp, Selina E; Bertuccini, Lucia; Wittlin, Sergio; Kasdin, Rachel G; Le Bihan, Amélie; Clozel, Martine; Winzeler, Elizabeth A; Alano, Pietro; Fidock, David A

    2016-08-01

    Emerging resistance to first-line antimalarial combination therapies threatens malaria treatment and the global elimination campaign. Improved therapeutic strategies are required to protect existing drugs and enhance treatment efficacy. We report that the piperazine-containing compound ACT-451840 exhibits single-digit nanomolar inhibition of the Plasmodium falciparum asexual blood stages and transmissible gametocyte forms. Genome sequence analyses of in vitro-derived ACT-451840-resistant parasites revealed single nucleotide polymorphisms in pfmdr1, which encodes a digestive vacuole membrane-bound ATP-binding cassette transporter known to alter P. falciparum susceptibility to multiple first-line antimalarials. CRISPR-Cas9 based gene editing confirmed that PfMDR1 point mutations mediated ACT-451840 resistance. Resistant parasites demonstrated increased susceptibility to the clinical drugs lumefantrine, mefloquine, quinine and amodiaquine. Stage V gametocytes harboring Cas9-introduced pfmdr1 mutations also acquired ACT-451840 resistance. These findings reveal that PfMDR1 mutations can impart resistance to compounds active against asexual blood stages and mature gametocytes. Exploiting PfMDR1 resistance mechanisms provides new opportunities for developing disease-relieving and transmission-blocking antimalarials.

  1. Overcoming doxorubicin resistance of cancer cells by Cas9-mediated gene disruption

    PubMed Central

    Ha, Jong Seong; Byun, Juyoung; Ahn, Dae-Ro

    2016-01-01

    In this study, Cas9 system was employed to down-regulate mdr1 gene for overcoming multidrug resistance of cancer cells. Disruption of the MDR1 gene was achieved by delivery of the Cas9-sgRNA plasmid or the Cas9-sgRNA ribonucleoprotein complex using a conventional gene transfection agent and protein transduction domain (PTD). Doxorubicin showed considerable cytotoxicity to the drug-resistant breast cancer cells pre-treated with the RNA-guided endonuclease (RGEN) systems, whereas virtually non-toxic to the untreated cells. The potency of drug was enhanced in the cells treated with the protein-RNA complex as well as in those treated with plasmids, suggesting that mutation of the mdr1 gene by intracellular delivery of Cas9-sgRNA complex using proper protein delivery platforms could recover the drug susceptibility. Therefore, Cas9-mediated disruption of the drug resistance-related gene can be considered as a promising way to overcome multidrug resistance in cancer cells. PMID:26961701

  2. Tubulin Beta3 Serves as a Target of HDAC3 and Mediates Resistance to Microtubule-Targeting Drugs.

    PubMed

    Kim, Youngmi; Kim, Hyuna; Jeoung, Dooil

    2015-08-01

    We investigated the role of HDAC3 in anti-cancer drug-resistance. The expression of HDAC3 was decreased in cancer cell lines resistant to anti-cancer drugs such as celastrol and taxol. HDAC3 conferred sensitivity to these anti-cancer drugs. HDAC3 activity was necessary for conferring sensitivity to these anti-cancer drugs. The down-regulation of HDAC3 increased the expression of MDR1 and conferred resistance to anti-cancer drugs. The expression of tubulin β3 was increased in drug-resistant cancer cell lines. ChIP assays showed the binding of HDAC3 to the promoter sequences of tubulin β3 and HDAC6. HDAC6 showed an interaction with tubulin β3. HDAC3 had a negative regulatory role in the expression of tubulin β3 and HDAC6. The down-regulation of HDAC6 decreased the expression of MDR1 and tubulin β3, but did not affect HDAC3 expression. The down-regulation of HDAC6 conferred sensitivity to taxol. The down-regulation of tubulin β3 did not affect the expression of HDAC6 or MDR1. The down-regulation of tubulin β3 conferred sensitivity to anti-cancer drugs. Our results showed that tubulin β3 serves as a downstream target of HDAC3 and mediates resistance to microtubule-targeting drugs. Thus, the HDAC3-HDAC6-Tubulin β axis can be employed for the development of anti-cancer drugs.

  3. Visualizing spatial distribution of alectinib in murine brain using quantitative mass spectrometry imaging

    PubMed Central

    Aikawa, Hiroaki; Hayashi, Mitsuhiro; Ryu, Shoraku; Yamashita, Makiko; Ohtsuka, Naoto; Nishidate, Masanobu; Fujiwara, Yasuhiro; Hamada, Akinobu

    2016-01-01

    In the development of anticancer drugs, drug concentration measurements in the target tissue have been thought to be crucial for predicting drug efficacy and safety. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is commonly used for determination of average drug concentrations; however, complete loss of spatial information in the target tissue occurs. Mass spectrometry imaging (MSI) has been recently applied as an innovative tool for detection of molecular distribution of pharmacological agents in heterogeneous targets. This study examined the intra-brain transitivity of alectinib, a novel anaplastic lymphoma kinase inhibitor, using a combination of matrix-assisted laser desorption ionization–MSI and LC-MS/MS techniques. We first analyzed the pharmacokinetic profiles in FVB mice and then examined the effect of the multidrug resistance protein-1 (MDR1) using Mdr1a/b knockout mice including quantitative distribution of alectinib in the brain. While no differences were observed between the mice for the plasma alectinib concentrations, diffuse alectinib distributions were found in the brain of the Mdr1a/b knockout versus FVB mice. These results indicate the potential for using quantitative MSI for clarifying drug distribution in the brain on a microscopic level, in addition to suggesting a possible use in designing studies for anticancer drug development and translational research. PMID:27026287

  4. Screening for impact of popular herbs improving mental abilities on the transcriptional level of brain transporters.

    PubMed

    Mrozikiewicz, Przemyslaw M; Bogacz, Anna; Bartkowiak-Wieczorek, Joanna; Kujawski, Radoslaw; Mikolajczak, Przemyslaw L; Ozarowski, Marcin; Czerny, Boguslaw; Mrozikiewicz-Rakowska, Beata; Grzeskowiak, Edmund

    2014-06-01

    There are a number of compounds that can modify the activity of ABC (ATP-binding cassette) and SLC (solute carrier) transporters in the blood-brain barrier (BBB). The aim of this study was to investigate the effect of natural and synthetic substances on the expression level of genes encoding transporters present in the BBB (mdr1a, mdr1b, mrp1, mrp2, oatp1a4, oatp1a5 and oatp1c1). Our results showed that verapamil caused the greatest reduction in the mRNA level while other synthetic (piracetam, phenobarbital) and natural (codeine, cyclosporine A, quercetin) substances showed a selective inhibitory effect. Further, the extract from the roots of Panax ginseng C. A. Meyer exhibited a decrease of transcription against selected transporters whereas the extract from Ginkgo biloba L. leaves resulted in an increase of the expression level of tested genes, except for mrp2. Extract from the aerial parts of Hypericum perforatum L. was the only one to cause an increased mRNA level for mdr1 and oatp1c1. These findings suggest that herbs can play an important role in overcoming the BBB and multidrug resistance to pharmacotherapy of brain cancer and mental disorders, based on the activity of selected drug-metabolizing enzymes and transporters located in the BBB. PMID:24914722

  5. The correlation of virulence, pathogenicity, and itraconazole resistance with SAP activity in Candida albicans strains.

    PubMed

    Feng, Wenli; Yang, Jing; Pan, Yanwei; Xi, Zhiqin; Qiao, Zusha; Ma, Yan

    2016-02-01

    The relationship between SAP2 activity and drug resistance in Candida albicans was investigated by using itraconazole-resistant and itraconazole-sensitive C. albicans isolates. The precipitation zones were measured to analyze SAP2 activity. Mice were classified into itraconazole-resistant and -sensitive C. albicans isolate groups, and a control group, with their survival and mortality rate being observed over 30 days. The relative expression levels of CDR1, CDR2, MDR1, and SAP2 were measured using RT-PCR. It was found that the secreted aspartyl proteinase activity of itraconazole-resistant C. albicans strains was significantly higher than that of itraconazole-sensitive C. albicans strains (P < 0.001). A significantly higher mortality rate was recorded for mice treated with itraconazole-resistant C. albicans than for mice treated with itraconazole-sensitive C. albicans. In regards to the CDR1, CDR2, and MDR1 genes, there was no significant difference between the 2 groups of mice. Positive correlations between SAP2 and MDR1 and between CDR1 and CDR2 were found. The high expression level of SAP2 may relate to the virulence, pathogenicity, and resistance of C. albicans.

  6. Differential effects of the organochlorine pesticide DDT and its metabolite p,p'-DDE on p-glycoprotein activity and expression

    SciTech Connect

    Shabbir, Arsalan; DiStasio, Susan; Zhao, Jingbo; Cardozo, Christopher P.; Wolff, Mary S.; Caplan, Avrom J. . E-mail: avrom.caplan@mssm.edu

    2005-03-01

    1,1-Bis(4-chlorophenyl)-2,2,2-trichloroethane (DDT) is an organochlorine pesticide. Its metabolite, 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethene (p,p'-DDE) is a persistent environmental contaminant and both compounds accumulate in animals. Because multidrug resistance transporters, such as p-glycoprotein, function as a defense against xenobiotic exposure, we analyzed the ability of DDT and p,p'-DDE to act as efflux modulators. Using a competitive intact cell assay based on the efflux of the fluorescent dye rhodamine 123, we found that DDT, but not p,p'-DDE, stimulated dye retention. Subsequent studies using verapamil as competitor suggested that DDT is a weak p-glycoprotein inhibitor. Further studies addressed the ability of DDT and p,p'-DDE to induce MDR1, the gene encoding p-glycoprotein. In HepG2 cells, we found that both compounds induced MDR1 by twofold to threefold. Similar results were observed in mouse liver after a single dose of p,p'-DDE, although some gender-specific induction differences were noted. By contrast, p,p'-DDE failed to induce MDR1 in HeLa cells, indicating some cell-specific effects for induction. Further expression studies demonstrated increased levels of the endoplasmic reticulum molecular chaperone, Bip, in response to DDT, but not p,p'-DDE. These results suggest that DDT, but not p,p'-DDE, induces an endoplasmic reticulum stress response.

  7. A very early induction of major vault protein accompanied by increased drug resistance in U-937 cells.

    PubMed

    Hu, Yi; Stephen, Andrew G; Cao, Jin; Tanzer, Lee R; Slapak, Christopher A; Harrison, Steadman D; Devanarayan, Viswanath; Dantzig, Anne H; Starling, James J; Rome, Leonard H; Moore, Robert E

    2002-01-10

    U-937 human leukemia cells were selected for resistance to doxorubicin in the presence or absence of a specific drug modulator that inhibits the activity of P-glycoprotein (Pgp), encoded by the multidrug-resistance gene (MDR1). Parental cells expressed low basal levels of the multidrug-resistance-associated gene (MRP1) and major vault protein (MVP) mRNAs and no MDR1 mRNA. Two doxorubicin-resistant cell lines were selected. Both drug-resistant cell lines upregulated the MVP mRNA level 1.5-fold within 1 cell passage. The MVP mRNA level continued to increase over time as the doxorubicin selection pressure was increased. MVP protein levels generally paralleled the mRNA levels. The 2 high molecular weight vault protein mRNAs were always expressed at constitutive levels. Fully formed vault particles consisting of the MVP, the 2 high molecular weight proteins and the vault RNA assembled and accumulated to increased levels in drug-selected cells. MVP induction is therefore the rate-limiting step for vault particle formation in U-937 cells. By passage 25 and thereafter, the selected cells were resistant to doxorubicin, etoposide, mitoxantrone and 5-fluorouracil by a pathway that was independent of MDR1, MRP1, MRP2 and breast cancer resistance protein. In summary, U-937 doxorubicin-selected cells are programmed to rapidly upregulate MVP mRNA levels, to accumulate vault particles and to become multidrug resistant.

  8. Separating the roles of acropetal and basipetal auxin transport on gravitropism with mutations in two Arabidopsis multidrug resistance-like ABC transporter genes.

    PubMed

    Lewis, Daniel R; Miller, Nathan D; Splitt, Bessie L; Wu, Guosheng; Spalding, Edgar P

    2007-06-01

    Two Arabidopsis thaliana ABC transporter genes linked to auxin transport by various previous results were studied in a reverse-genetic fashion. Mutations in Multidrug Resistance-Like1 (MDR1) reduced acropetal auxin transport in roots by 80% without affecting basipetal transport. Conversely, mutations in MDR4 blocked 50% of basipetal transport without affecting acropetal transport. Developmental and auxin distribution phenotypes associated with these altered auxin flows were studied with a high-resolution morphometric system and confocal microscopy, respectively. Vertically grown mdr1 roots produced positive and negative curvatures threefold greater than the wild type, possibly due to abnormal auxin distribution observed in the elongation zone. However, upon 90 degrees reorientation, mdr1 gravitropism was inseparable from the wild type. Thus, acropetal auxin transport maintains straight growth but contributes surprisingly little to gravitropism. Conversely, vertically maintained mdr4 roots grew as straight as the wild type, but their gravitropism was enhanced. Upon reorientation, curvature in this mutant developed faster, was distributed more basally, and produced a greater total angle than the wild type. An amplified auxin asymmetry may explain the mdr4 hypertropism. Double mutant analysis indicated that the two auxin transport streams are more independent than interdependent. The hypothesis that flavanols regulate MDR-dependent auxin transport was supported by the epistatic relationship of mdr4 to the tt4 phenylpropanoid pathway mutation.

  9. Piperine activates human pregnane X receptor to induce the expression of cytochrome P450 3A4 and multidrug resistance protein 1

    PubMed Central

    Wang, Yue-Ming; Lin, Wenwei; Chai, Sergio C.; Wu, Jing; Ong, Su Sien; Schuetz, Erin G.; Chen, Taosheng

    2013-01-01

    Activation of the pregnane X receptor (PXR) and subsequently its target genes, including those encoding drug transporters and metabolizing enzymes, while playing substantial roles in xenobiotics detoxification, might cause undesired drug-drug interactions. Recently, an increased awareness has been given to dietary components for potential induction of diet-drug interactions through activation of PXR. Here, we studied, whether piperine (PIP), a major component extracted from the widely-used daily spice black pepper, could induce PXR-mediated expression of cytochrome P450 3A4 (CYP3A4) and multidrug resistance protein 1 (MDR1). Our results showed that PIP activated human PXR (hPXR)-mediated CYP3A4 and MDR1 expression in human hepatocytes, intestine cells, and a mouse model; PIP activated hPXR by recruiting its coactivator SRC-1 in both cellular and cell-free systems; PIP bound to the hPXR ligand binding domain in a competitive ligand binding assay in vitro. The dichotomous effects of PIP on induction of CYP3A4 and MDR1 expression observed here and inhibition of their activity reported elsewhere challenges the potential use of PIP as a bioavailability enhancer and suggests that cautions should be taken for PIP consumption during drug treatment in patients, particularly those who favor daily pepper spice or rely on certain pepper remedies. PMID:23707768

  10. Separating the Roles of Acropetal and Basipetal Auxin Transport on Gravitropism with Mutations in Two Arabidopsis Multidrug Resistance-Like ABC Transporter Genes[W][OA

    PubMed Central

    Lewis, Daniel R.; Miller, Nathan D.; Splitt, Bessie L.; Wu, Guosheng; Spalding, Edgar P.

    2007-01-01

    Two Arabidopsis thaliana ABC transporter genes linked to auxin transport by various previous results were studied in a reverse-genetic fashion. Mutations in Multidrug Resistance-Like1 (MDR1) reduced acropetal auxin transport in roots by 80% without affecting basipetal transport. Conversely, mutations in MDR4 blocked 50% of basipetal transport without affecting acropetal transport. Developmental and auxin distribution phenotypes associated with these altered auxin flows were studied with a high-resolution morphometric system and confocal microscopy, respectively. Vertically grown mdr1 roots produced positive and negative curvatures threefold greater than the wild type, possibly due to abnormal auxin distribution observed in the elongation zone. However, upon 90° reorientation, mdr1 gravitropism was inseparable from the wild type. Thus, acropetal auxin transport maintains straight growth but contributes surprisingly little to gravitropism. Conversely, vertically maintained mdr4 roots grew as straight as the wild type, but their gravitropism was enhanced. Upon reorientation, curvature in this mutant developed faster, was distributed more basally, and produced a greater total angle than the wild type. An amplified auxin asymmetry may explain the mdr4 hypertropism. Double mutant analysis indicated that the two auxin transport streams are more independent than interdependent. The hypothesis that flavanols regulate MDR-dependent auxin transport was supported by the epistatic relationship of mdr4 to the tt4 phenylpropanoid pathway mutation. PMID:17557805

  11. Evaluation of blood-brain barrier and blood-cerebrospinal fluid barrier permeability of 2-phenoxy-indan-1-one derivatives using in vitro cell models.

    PubMed

    Hu, Hai-Hong; Bian, Yi-Cong; Liu, Yao; Sheng, Rong; Jiang, Hui-Di; Yu, Lu-Shan; Hu, Yong-Zhou; Zeng, Su

    2014-01-01

    2-Phenoxy-indan-1-one derivatives (PIOs) are a series of novel central-acting cholinesterase inhibitors for the treatment of Alzheimer's disease (AD). The adequate distribution of PIOs to the central nervous system (CNS) is essential for its effectiveness. However, articles related with their permeability in terms of CNS penetration across the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB) have not been found. This study was undertaken to evaluate the in vitro BBB and BCSFB transport of PIOs using Madin-Darby canine kidney (MDCK), MDCK-MDR1 and Z310 cell line models. As a result, the transepithelial transport of PIOs did not differ between MDCK and MDCK-MDR1, and the result suggested that PIOs were not substrates for P-gp, which means that multidrug resistance (MDR) function would not affect PIOs absorption and brain distribution. High permeability of PIOs in Z310 was found and it suggested that PIOs had high brain uptake potential. The experiment also showed that PIOs had inhibitory effects on the MDR1-mediated transport of Rhodamine123 with an IC50 value of 40-54 μM. And we suggested that 5,6-dimethoxy-1-indanone might be the pharmacophoric moiety of PIOs that interacts with the binding site of P-gp. PMID:24262988

  12. A robust and versatile signal-on fluorescence sensing strategy based on SYBR Green I dye and graphene oxide

    PubMed Central

    Qiu, Huazhang; Wu, Namei; Zheng, Yanjie; Chen, Min; Weng, Shaohuang; Chen, Yuanzhong; Lin, Xinhua

    2015-01-01

    A robust and versatile signal-on fluorescence sensing strategy was developed to provide label-free detection of various target analytes. The strategy used SYBR Green I dye and graphene oxide as signal reporter and signal-to-background ratio enhancer, respectively. Multidrug resistance protein 1 (MDR1) gene and mercury ion (Hg2+) were selected as target analytes to investigate the generality of the method. The linear relationship and specificity of the detections showed that the sensitive and selective analyses of target analytes could be achieved by the proposed strategy with low detection limits of 0.5 and 2.2 nM for MDR1 gene and Hg2+, respectively. Moreover, the strategy was used to detect real samples. Analytical results of MDR1 gene in the serum indicated that the developed method is a promising alternative approach for real applications in complex systems. Furthermore, the recovery of the proposed method for Hg2+ detection was acceptable. Thus, the developed label-free signal-on fluorescence sensing strategy exhibited excellent universality, sensitivity, and handling convenience. PMID:25565810

  13. Synthesis and in vivo evaluation of [11C]tariquidar, a positron emission tomography radiotracer based on a third-generation P-glycoprotein inhibitor

    PubMed Central

    Bauer, Florian; Kuntner, Claudia; Bankstahl, Jens P.; Wanek, Thomas; Bankstahl, Marion; Stanek, Johann; Mairinger, Severin; Dörner, Bernd; Löscher, Wolfgang; Müller, Markus; Erker, Thomas; Langer, Oliver

    2013-01-01

    The aim of this study was to develop a positron emission tomography (PET) tracer based on the dual P-glycoprotein (P-gp) breast cancer resistance protein (BCRP) inhibitor tariquidar (1) to study the interaction of 1 with P-gp and BCRP in the blood-brain barrier (BBB) in vivo. O-desmethyl-1 was synthesized and reacted with [11C]methyl triflate to afford [11C]-1. Small-animal PET imaging of [11C]-1 was performed in naïve rats, before and after administration of unlabeled 1 (15 mg/kg, n=3) or the dual P-gp/BCRP inhibitor elacridar (5 mg/kg, n=2), as well as in wild-type, Mdr1a/b(−/−), Bcrp1(−/−) and Mdr1a/b(−/−)Bcrp1(−/−) mice (n=3). In vitro autoradiography was performed with [11C]-1 using brain sections of all 4 mouse types, with and without co-incubation with unlabeled 1 or elacridar (1 μM). In PET experiments in rats, administration of unlabeled 1 or elacridar increased brain activity uptake by a factor of 3-4, whereas blood activity levels remained unchanged. In Mdr1a/b(−/−), Bcrp1(−/−) and Mdr1a/b(−/−)Bcrp1(−/−) mice, brain-to-blood ratios of activity at 25 min after tracer injection were 3.4, 1.8 and 14.5 times higher, respectively, as compared to wild-type animals. Autoradiography showed approximately 50% less [11C]-1 binding in transporter knockout mice compared to wild-type mice and significant displacement by unlabeled elacridar in wild-type and Mdr1a/b(−/−) mouse brains. Our data suggest that [11C]-1 interacts specifically with P-gp and BCRP in the BBB. However, further investigations are needed to assess if [11C]-1 behaves in vivo as a transported or a non-transported inhibitor. PMID:20621487

  14. Peroxisome proliferator-activated receptor alpha (PPARalpha)-mediated regulation of multidrug resistance 2 (Mdr2) expression and function in mice.

    PubMed Central

    Kok, Tineke; Bloks, Vincent W; Wolters, Henk; Havinga, Rick; Jansen, Peter L M; Staels, Bart; Kuipers, Folkert

    2003-01-01

    Peroxisome proliferator-activated receptor alpha (PPARalpha) is a nuclear receptor that controls expression of genes involved in lipid metabolism and is activated by fatty acids and hypolipidaemic fibrates. Fibrates induce the hepatic expression of murine multidrug resistance 2 ( Mdr2 ), encoding the canalicular phospholipid translocator. The physiological role of PPARalpha in regulation of Mdr2 and other genes involved in bile formation is unknown. We found no differences in hepatic expression of the ATP binding cassette transporter genes Mdr2, Bsep (bile salt export pump), Mdr1a / 1b, Abca1 and Abcg5 / Abcg8 (implicated in cholesterol transport), the bile salt-uptake systems Ntcp (Na(+)-taurocholate co-transporting polypeptide gene) and Oatp1 (organic anion-transporting polypeptide 1 gene) or in bile formation between wild-type and Ppar alpha((-/-)) mice. Upon treatment of wild-type mice with ciprofibrate (0.05%, w/w, in diet for 2 weeks), the expression of Mdr2 (+3-fold), Mdr1a (+6-fold) and Mdr1b (+11-fold) mRNAs was clearly induced, while that of Oatp1 (-5-fold) was reduced. Mdr2 protein levels were increased, whereas Bsep, Ntcp and Oatp1 were drastically decreased. Exposure of cultured wild-type mouse hepatocytes to PPARalpha agonists specifically induced Mdr2 mRNA levels and did not affect expression of Mdr1a / 1b. Altered transporter expression in fibrate-treated wild-type mice was associated with a approximately 400% increase in bile flow: secretion of phospholipids and cholesterol was increased only during high-bile-salt infusions. No fibrate effects were observed in Ppar alpha((-/-)) mice. In conclusion, our results show that basal bile formation is not affected by PPARalpha deficiency in mice. The induction of Mdr2 mRNA and Mdr2 protein levels by fibrates is mediated by PPARalpha, while the induction of Mdr1a / 1b in vivo probably reflects a secondary phenomenon related to chronic PPARalpha activation. PMID:12381268

  15. Chemoresistance of CD133(+) colon cancer may be related with increased survivin expression.

    PubMed

    Lee, Mi-Ra; Ji, Sun-Young; Mia-Jan, Khalilullah; Cho, Mee-Yon

    2015-07-31

    CD133, putative cancer stem cell marker, deemed to aid chemoresistance. However, this claim has been challenged recently and we previously reported that patients with CD133(+) colon cancer have benefit from 5-fluorouracil (5-FU) chemotherapy incontrast to no benefit in patients with CD133(-) cancer. To elucidate the role of CD133 expression in chemoresistance, we silenced the CD133 expression in a colon cancer cell line and determined its effect on the biological characteristics downstream. We comparatively analyzed the sequential changes of MDR1, ABCG2, AKT1 and survivin expression and the result of proliferation assay (WST-1 assay) with 5-FU treatment in CD133(+) and siRNA-induced CD133(-) cells, derived from Caco-2 colon cancer cell line. 5-FU treatment induced significantly increase of the mRNA expression of MDR1, ABCG2 and AKT1genes, but not protein level. CD133 had little to no effect on the mRNA and protein expression of these genes. However, survivin expression at mRNA and protein level were significantly increased in CD133(+) cells compared with siRNA-induced CD133-cells and Mock (not sorted CD133(+) cells) at 96 h after siRNA transfection. The cytotoxicity assay demonstrated notable increase of chemoresistance to 5-FU treatment (10 μM) in CD133(+) cells at 96 h after siRNA transfection. From this study, we conclude that CD133(+) cells may have chemoresistance to 5-FU through the mechanism which is related with survivin expression, instead of MDR1, ABCG2 and AKT1 expression. Therefore a survivin inhibitor can be a new target for effective treatment of CD133(+) colon cancer.

  16. High expression of miR-9 in CD133+ glioblastoma cells in chemoresistance to temozolomide

    PubMed Central

    Munoz, Jessian L.; Rodriguez-Cruz, Vivian; Rameshwar, Pranela

    2016-01-01

    Glioblastoma Multiforme (GBM), a uniformly lethal stage IV astrocytoma, is currently treated with a combination of surgical and radiation therapy as well as Temozolomide (TMZ) chemotherapy. Resistance to TMZ is rapidly acquired by GBM cells and overcoming this resistance has been an area of signi?cant research. GBM 'cancer stem cells' (CSC) also known as 'cancer initiating cells' are often positively selected by CD133 expression and TMZ resistance. In this project, we selected GBM CSC from two cell lines based on CD133 expression. CD133+ and CD133− GBM cells showed comparable cell cycle status. The expression of genes within the Sonic Hedgehog Signaling pathway, PTCH1 (SHH receptor/basal signaling repressor) and Gli1 (effector transcription factor) were increased. The recent literature indicated a decreased in PTCH expression by miRNA and this was independent of SHH expression. We analyzed 5 potential PTCH-targeting miRNA and identi?ed an increase in miRNA-9-2. The CD133+ cells showed an increase in the Multiple Drug Resistance 1 gene (MDR1). Knockdown of Gli1 and MDR1 with siRNA enhanced TMZ induced cell death. Taken together, these studies show CD133+ GBM CSCs expressed greater levels of miR-9 and activation of the SHH/PTCH1/MDR1 axis. This axis has been shown to impart TMZ resistance. In the case of the CD133+ cells, the resistance is not acquires but seems to be inherent. Identi?cation of this pathway as well as the identi?cation of miR-9 may allow for the development of miRNA-targeted approach to Cancer Stem Cell therapy in GBM. PMID:27347493

  17. [Effect of Siwu decoction on function and expression of P-glycoprotein in Caco-2 cells].

    PubMed

    Jiang, Yi; Ma, Zeng-chun; Huang, Xian-ju; You, Qing; Tan, Hong-ling; Wang, Yu-guang; Liang, Qian-de; Tang, Xiang-lin; Xiao, Cheng-rong; Gao, Yue

    2015-03-01

    To study the effect of Siwu decoction on the function and expression of P-glycoprotein (P-gp) in Caco-2 cells. The Real-time quantitative poly-merase chain reaction (Q-PCR) was used to analyze the mRNA expression of MDR1 gene in Caco-2 cells. Flow cytometer was used to study the effect of Siwu decoction on the uptake of Rhodamine 123 in Caco-2 cells, in order to evaluate the efflux function of P-gp. Western blotting method was used to detect the effect of Siwu decoction on the P-gp protein expression of Caco-2 cells. Compared with the blank control group, after Caco-2 incubation with Siwu decoction at concentrations of 3.3, 5.0, 10.0 g x L(-1) for 24, 48, 72 h, the mRNA expression of MDR1 was up-regulated, suggesting the effect of Siwu decoction in inducing the expression of MDR1. After the administration with Siwu decoction in Caco-2 cells for 48 h, the uptake of Rhodamine 123 in Caco-2 cells decreased by respectively 16.6%, 22.1% (P < 0.05) and 45.4% (P < 0.01), indicating that the long-term administration of Siwu decoction can enhance the P-gp efflux function of Caco-2 cells. After the incubation of Caco-2 cells with Siwu decoction for 48 h, the P-gp protein expression on Caco-2 cell emebranes, demonstrating the effect of Siwu decoction in inducing the protein expression of P-gp.

  18. Oral Serum-Derived Bovine Immunoglobulin/Protein Isolate Has Immunomodulatory Effects on the Colon of Mice that Spontaneously Develop Colitis

    PubMed Central

    Maijó, Mònica; Polo, Javier; Campbell, Joy M.; Russell, Louis; Crenshaw, Joe D.; Weaver, Eric; Moretó, Miquel

    2016-01-01

    Dietary immunoglobulin concentrates prepared from animal plasma can modulate the immune response of gut-associated lymphoid tissue (GALT). Previous studies have revealed that supplementation with serum-derived bovine immunoglobulin/protein isolate (SBI) ameliorates colonic barrier alterations in the mdr1a-/- genetic mouse model of IBD. Here, we examine the effects of SBI on mucosal inflammation in mdr1a-/- mice that spontaneously develop colitis. Wild type (WT) mice and mice lacking the mdr1a gene (KO) were fed diets supplemented with either SBI (2% w/w) or milk proteins (Control diet), from day 21 (weaning) until day 56. Leucocytes in mesenteric lymph nodes (MLN) and in lamina propria were determined, as was mucosal cytokine production. Neutrophil recruitment and activation in MLN and lamina propria of KO mice were increased, but were significantly reduced in both by SBI supplementation (p < 0.05). The increased neutrophil recruitment and activation observed in KO mice correlated with increased colon oxidative stress (p < 0.05) and SBI supplementation reduced this variable (p < 0.05). The Tact/Treg lymphocyte ratios in MLN and lamina propria were also increased in KO animals, but SBI prevented these changes (both p < 0.05). In the colon of KO mice, there was an increased production of mucosal pro-inflammatory cytokines such as IL-2 (2-fold), IL-6 (26-fold) and IL-17 (19-fold), and of chemokines MIP-1β (4.5-fold) and MCP-1 (7.2-fold). These effects were significantly prevented by SBI (p < 0.05). SBI also significantly increased TGF-β secretion in the colon mucosa, suggesting a role of this anti-inflammatory cytokine in the modulation of GALT and the reduction of the severity of the inflammatory response during the onset of colitis. PMID:27139220

  19. Role and mechanism of Twist1 in modulating the chemosensitivity of FaDu cells.

    PubMed

    Lu, Sumei; Yu, Liang; Mu, Yakui; Ma, Juke; Tian, Jiajun; Xu, Wei; Wang, Haibo

    2014-07-01

    Multidrug resistance (MDR) is one of the most important obstacles affecting the efficacy of chemotherapy treatments for numerous types of cancer. In the present study, we have demonstrated the possible function of Twist1 in the chemosensitivity of head and neck squamous cell carcinoma (HNSCC) and have identified that its mechanism maybe associated with MDR1/P-gp regulation. To investigate this, the hypopharyngeal cancer cell line, FaDu, and its MDR cell line induced by taxol, FaDu/T, were employed. Stable transfectants targeted to Twist1 overexpression and Twist1 silencing based on FaDu were also conducted. Morphological observation, flow cytometry, reverse transcription-polymerase chain reaction (RT-PCR), western blotting and laser scanning confocal microscope detection were utilized to detect the associations between Twist1 and the chemosensitivity of FaDu cells. Our results demonstrated that Twist1 and MDR1/P-gp were upregulated in FaDu/T cells in a MDR dose-dependent manner. The anti-apoptotic capabilities of FaDu/T cells were enhanced during MDR progression, with apoptosis-related proteins (Bcl-2, Bax, activated caspase-3 and caspase-9) changing to resist apoptosis. Twist1 overexpression decreased the sensitivity of cells to taxol as revealed by a significant increase in MDR1/P-gp and IC50 (P<0.05). This overexpression also enhanced the resistance to apoptosis, with apoptotic proteins changing to resist cell death, and inhibited Ca2+ release induced by taxol (P<0.05). Detections in Twist1 silencing cells also confirmed this result. This study provided evidence that alterations of Twist1 expression modulates the chemosensitivity of FaDu cells to taxol. Therefore, Twist1 knockdown may be a promising treatment regimen for advanced hypopharyngeal carcinoma patients with MDR.

  20. Cloning and characterization of a second member of the mouse mdr gene family.

    PubMed Central

    Gros, P; Raymond, M; Bell, J; Housman, D

    1988-01-01

    The mammalian mdr gene family comprises a small number of closely related genes. Previously, we have shown that one member, mdr1, has the capacity to convey multidrug resistance to drug-sensitive recipient cells in a gene transfer protocol. However, the functional characteristics of other members of this gene family have not been examined. In this report, we characterize a second member of the mdr gene family which we designated mdr2. We determined the nucleotide sequence corresponding to the complete coding region of this mdr2 transcript. The predicted amino acid sequence of this protein (1,276 amino acids) showed that it is a membrane glycoprotein highly homologous to mdr1 (85%), strongly suggesting that both genes originate from a common ancestor. Regions of divergence between mdr1 and mdr2 proteins are concentrated in two discrete segments of the predicted polypeptides, each approximately 100 residues in length. The mdr2 protein appears to be formed by the duplication of a structural unit which encodes three putative transmembrane loops and a predicted nucleotide-binding fold and is highly homologous to bacterial transport proteins such as hlyB. This strong homology suggests that mdr2 also participates in an energy-dependent membrane transport process. However, the direct relationship, if any, of this new member of the mdr family to multidrug resistance remains to be established. Knowledge of the complete nucleotide sequence and predicted amino acid sequence of the mdr2 gene product will enable the preparation of gene-specific probes and antibodies necessary to study the functional role of this gene in multidrug resistance and normal physiological processes. PMID:3405218

  1. Troglitazone reverses the multiple drug resistance phenotype in cancer cells

    PubMed Central

    Davies, Gerald F; Juurlink, Bernhard HJ; Harkness, Troy AA

    2009-01-01

    A major problem in treating cancer is the development of drug resistance. We previously demonstrated doxorubicin (DOX) resistance in K562 human leukemia cells that was associated with upregulation of glyoxalase 1 (GLO-1) and histone H3 expression. The thiazolidinedione troglitazone (TRG) downregulated GLO-1 expression and further upregulated histone H3 expression and post-translational modifications in these cells, leading to a regained sensitivity to DOX. Given the pleiotropic effects of epigenetic changes in cancer development, we hypothesized that TRG may downregulate the multiple drug resistance (MDR) phenotype in a variety of cancer cells. To test this, MCF7 human breast cancer cells and K562 cells were cultured in the presence of low-dose DOX to establish DOX-resistant cell lines (K562/DOX and MCF7/DOX). The MDR phenotype was confirmed by Western blot analysis of the 170 kDa P-glycoprotein (Pgp) drug efflux pump multiple drug resistance protein 1 (MDR-1), and the breast cancer resistance protein (BCRP). TRG markedly decreased expression of both MDR-1 and BCRP in these cells, resulting in sensitivity to DOX. Silencing of MDR-1 expression also sensitized MCF7/DOX cells to DOX. Use of the specific and irreversible peroxisome proliferator-activated receptor gamma (PPARγ) inhibitor GW9662 in the nanomolar range not only demonstrated that the action of TRG on MCF/DOX was PPARγ-independent, but indicated that PPARγ may play a role in the MDR phenotype, which is antagonized by TRG. We conclude that TRG is potentially a useful adjunct therapy in chemoresistant cancers. PMID:19920924

  2. Interspecies variability in expression of hepatobiliary transporters across human, dog, monkey, and rat as determined by quantitative proteomics.

    PubMed

    Wang, Li; Prasad, Bhagwat; Salphati, Laurent; Chu, Xiaoyan; Gupta, Anshul; Hop, Cornelis E C A; Evers, Raymond; Unadkat, Jashvant D

    2015-03-01

    We quantified, by liquid chromatography tandem mass spectrometry, transporter protein expression of BSEP, MATE1, MRP3, MRP4, NTCP, and OCT1 in our human liver bank (n = 55) and determined the relationship between protein expression and sex, age and genotype. These data complement our previous work in the same liver bank where we quantified the protein expression of OATPs, BCRP, MDR1, and MRP2. In addition, we quantified and compared the interspecies differences in expression of the hepatobiliary transporters, corresponding to the above human transporters, in liver tissue and hepatocytes of male beagle dogs, cynomolgus monkeys, Sprague-Dawley rats, and Wistar rats. In all the species, the sinusoidal OATPs/Oatps were the most abundant hepatic transporters. However, there were notable interspecies differences in the relative abundance of the remaining transporters. For example, the next most abundant transporter in humans and monkeys was OCT1/Oct1, whereas it was Mrp2 and Ntcp in dogs/Wistar rats and Sprague-Dawley rats, respectively. In contrast, the protein expression of the efflux transporters BCRP/Bcrp, MDR1/Mdr1, MRP3/Mrp3, MRP4/Mrp4, and MATE1/Mate1 was much lower across all the species. For most transporters, the expression in the liver tissues was comparable to that in the unplated cryopreserved hepatocytes. These data on human liver transporter protein expression complete the picture of the expression of major human hepatobiliary transporters important in drug disposition and toxicity. In addition, the data on expression of the corresponding hepatobiliary transporters in preclinical species will be helpful in interpreting and extrapolating pharmacokinetic, pharmacological, and toxicological results from preclinical studies to humans.

  3. Thyroid Hormone and P-Glycoprotein in Tumor Cells

    PubMed Central

    Davis, Paul J.; Lin, Hung-Yun; Sudha, Thangirala; Mousa, Shaker A.

    2015-01-01

    P-glycoprotein (P-gp; multidrug resistance pump 1, MDR1; ABCB1) is a plasma membrane efflux pump that when activated in cancer cells exports chemotherapeutic agents. Transcription of the P-gp gene (MDR1) and activity of the P-gp protein are known to be affected by thyroid hormone. A cell surface receptor for thyroid hormone on integrin αvβ3 also binds tetraiodothyroacetic acid (tetrac), a derivative of L-thyroxine (T4) that blocks nongenomic actions of T4 and of 3,5,3′-triiodo-L-thyronine (T3) at αvβ3. Covalently bound to a nanoparticle, tetrac as nanotetrac acts at the integrin to increase intracellular residence time of chemotherapeutic agents such as doxorubicin and etoposide that are substrates of P-gp. This action chemosensitizes cancer cells. In this review, we examine possible molecular mechanisms for the inhibitory effect of nanotetrac on P-gp activity. Mechanisms for consideration include cancer cell acidification via action of tetrac/nanotetrac on the Na+/H+ exchanger (NHE1) and hormone analogue effects on calmodulin-dependent processes and on interactions of P-gp with epidermal growth factor (EGF) and osteopontin (OPN), apparently via αvβ3. Intracellular acidification and decreased H+ efflux induced by tetrac/nanotetrac via NHE1 is the most attractive explanation for the actions on P-gp and consequent increase in cancer cell retention of chemotherapeutic agent-ligands of MDR1 protein. PMID:25866761

  4. A novel PET protocol for visualization of breast cancer resistance protein function at the blood–brain barrier

    PubMed Central

    Wanek, Thomas; Kuntner, Claudia; Bankstahl, Jens P; Mairinger, Severin; Bankstahl, Marion; Stanek, Johann; Sauberer, Michael; Filip, Thomas; Erker, Thomas; Müller, Markus; Löscher, Wolfgang; Langer, Oliver

    2012-01-01

    Breast cancer resistance protein (BCRP) is the most abundant multidrug efflux transporter at the human blood–brain barrier (BBB), restricting brain distribution of various drugs. In this study, we developed a positron emission tomography (PET) protocol to visualize Bcrp function at the murine BBB, based on the dual P-glycoprotein (P-gp)/Bcrp substrate radiotracer [11C]tariquidar in combination with the Bcrp inhibitor Ko143. To eliminate the contribution of P-gp efflux to [11C]tariquidar brain distribution, we studied mice in which P-gp was genetically knocked out (Mdr1a/b(−/−) mice) or chemically knocked out by pretreatment with cold tariquidar. We found that [11C]tariquidar brain uptake increased dose dependently after administration of escalating doses of Ko143, both in Mdr1a/b(−/−) mice and in tariquidar pretreated wild-type mice. After 15 mg/kg Ko143, the maximum increase in [11C]tariquidar brain uptake relative to baseline scans was 6.3-fold in Mdr1a/b(−/−) mice with a half-maximum effect dose of 4.98 mg/kg and 3.6-fold in tariquidar (8 mg/kg) pretreated wild-type mice, suggesting that the presented protocol is sensitive to visualize a range of different functional Bcrp activities at the murine BBB. We expect that this protocol can be translated to the clinic, because tariquidar can be safely administered to humans at doses that completely inhibit cerebral P-gp. PMID:22828996

  5. Activity of Isavuconazole and Other Azoles against Candida Clinical Isolates and Yeast Model Systems with Known Azole Resistance Mechanisms

    PubMed Central

    Coste, Alix T.

    2015-01-01

    Isavuconazole is a novel, broad-spectrum, antifungal azole. In order to evaluate its interactions with known azole resistance mechanisms, isavuconazole susceptibility among different yeast models and clinical isolates expressing characterized azole resistance mechanisms was tested and compared to those of fluconazole, itraconazole, posaconazole, and voriconazole. Saccharomyces cerevisiae expressing the Candida albicans and C. glabrata ATP binding cassette (ABC) transporters (CDR1, CDR2, and CgCDR1), major facilitator (MDR1), and lanosterol 14-α-sterol-demethylase (ERG11) alleles with mutations were used. In addition, pairs of C. albicans and C. glabrata strains from matched clinical isolates with known azole resistance mechanisms were investigated. The expression of ABC transporters increased all azole MICs, suggesting that all azoles tested were substrates of ABC transporters. The expression of MDR1 did not increase posaconazole, itraconazole, and isavuconazole MICs. Relative increases of azole MICs (from 4- to 32-fold) were observed for fluconazole, voriconazole, and isavuconazole when at least two mutations were present in the same ERG11 allele. Upon MIC testing of azoles with clinical C. albicans and C. glabrata isolates with known resistance mechanisms, the MIC90s of C. albicans for fluconazole, voriconazole, itraconazole, posaconazole, and isavuconazole were 128, 2, 1, 0.5, and 2 μg/ml, respectively, while in C. glabrata they were 128, 2, 4, 4, and 16 μg/ml, respectively. In conclusion, the effects of azole resistance mechanisms on isavuconazole did not differ significantly from those of other azoles. Resistance mechanisms in yeasts involving ABC transporters and ERG11 decreased the activity of isavuconazole, while MDR1 had limited effect. PMID:26482310

  6. Multimodal transfer of MDR by exosomes in human osteosarcoma.

    PubMed

    Torreggiani, Elena; Roncuzzi, Laura; Perut, Francesca; Zini, Nicoletta; Baldini, Nicola

    2016-07-01

    Exosomes are extracellular vesicles released by both normal and tumour cells which are involved in a new intercellular communication pathway by delivering cargo (e.g., proteins, microRNAs, mRNAs) to recipient cells. Tumour-derived exosomes have been shown to play critical roles in different stages of tumour growth and progression. In this study, we investigated the potential role of exosomes to transfer the multidrug resistance (MDR) phenotype in human osteosarcoma cells. Exosomes were isolated by differential centrifugation of culture media from multidrug resistant human osteosarcoma MG-63DXR30 (Exo/DXR) and MG-63 parental cells (Exo/S). Exosome purity was examined by transmission electron microscopy and confirmed by immunoblot analysis for the expression of specific exosomal markers. Our data showed that exosomes derived from doxorubicin-resistant osteosarcoma cells could be taken up into secondary cells and induce a doxorubicin-resistant phenotype. The incubation of osteosarcoma cells with Exo/DXR decreased the sensitivity of parental cells to doxorubicin, while exposure with Exo/S was ineffective. In addition, we demonstrated that Exo/DXR expressed higher levels of MDR-1 mRNA and P-glycoprotein compared to Exo/S (p=0.03). Interestingly, both MDR-1 mRNA and P-gp increased in MG-63 cells after incubation with Exo/DXR, suggesting this as the main mechanism of exosome-mediated transfer of drug resistance. Our findings suggest that multidrug resistant osteosarcoma cells are able to spread their ability to resist the effects of doxorubicin treatment on sensitive cells by transferring exosomes carrying MDR-1 mRNA and its product P-glycoprotein. PMID:27176642

  7. Methods of inducing inflammatory bowel disease in mice.

    PubMed

    Maxwell, Joseph R; Brown, William A; Smith, Carole L; Byrne, Fergus R; Viney, Joanne L

    2009-12-01

    Animal models of experimentally induced inflammatory bowel disease (IBD) are useful for understanding more about the mechanistic basis of disease, identifying new targets for therapeutic intervention, and testing novel therapeutic agents. This unit provides detailed protocols for four of the most commonly used mouse models of experimentally induced intestinal inflammation: chemical induction of colitis by dextran sodium sulfate (DSS), hapten-induced colitis via 2,4,6-trinitrobenzene sulfonic acid (TNBS), Helicobacter-induced colitis in mdr1a(-/-) mice, and the CD4(+) CD45RB(hi) SCID transfer colitis model.

  8. Evaluation of the near infrared compound indocyanine green as a probe substrate of p-glycoprotein.

    PubMed

    Portnoy, Emma; Gurina, Marina; Magdassi, Shlomo; Eyal, Sara

    2012-12-01

    The efflux transporter P-glycoprotein (P-gp) affects the pharmacokinetics of many drugs. Currently used methods for characterization of P-gp's functional activity in vivo involve the use of radiolabeled substrates, are costly, and are technically demanding. Our objective was to evaluate whether the FDA-approved near-infrared compound indocyanine green (ICG) can be used as a probe substrate of P-gp. We also characterized the interaction of ICG with another efflux transporter, the breast cancer resistance protein (BCRP). We evaluated ICG accumulation and transport in MDCK cells overexpressing P-gp or BCRP (MDCK-MDR1 and MDCK-BCRP, respectively) compared to control MDCK cells, in the presence or the absence of transporter inhibitors. In vivo imaging of ICG biodistribution in mice was conducted over 3.5 h using valspodar as the P-gp inhibitor. The EC50 values for ICG accumulation in control MDCK and MDCK-MDR1 cells were 9.0 × 10(-6) ± 5.7 × 10(-7) M and 1.5 × 10(-5) ± 1.1 × 10(-6) M, respectively. The efflux ratio for ICG in MDCK-MDR1 cells was 6.8-fold greater than in control cells. P-gp inhibition attenuated ICG efflux from MDR1-MDCK cells, and their effects in those cells were greater than in control MDCK cells. In contrast, BCRP level of expression or pharmacological inhibition did not significantly affect ICG cellular accumulation. In vivo imaging indicated enhanced cerebral ICG distribution with valspodar (brain - foot area under the concentration-time curves of 3.0 × 10(10), 5.6 × 10(10) and 3.7 × 10(10) h·[p/s/sr]/μW in valspodar-treated mice vs 9.0 × 10(9) and 5.3 × 10(9) h·[p/s/sr]/μW in controls). The findings from this pilot study suggest that near-infrared imaging using ICG as the probe substrate should be further characterized as a methodology for in vivo evaluation of P-gp activity.

  9. Assessment of the therapeutic efficacy of artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal: an observational cohort study

    PubMed Central

    2012-01-01

    Background Recent malaria epidemics in KwaZulu-Natal indicate that effective anti-malarial therapy is essential for malaria control. Although artemether-lumefantrine has been used as first-line treatment for uncomplicated Plasmodium falciparum malaria in northern KwaZulu-Natal since 2001, its efficacy has not been assessed since 2002. The objectives of this study were to quantify the proportion of patients treated for uncomplicated P. falciparum malaria with artemether-lumefantrine who failed treatment after 28 days, and to determine the prevalence of molecular markers associated with artemether-lumefantrine and chloroquine resistance. Methods An observational cohort of 49 symptomatic patients, diagnosed with uncomplicated P. falciparum malaria by rapid diagnostic test, had blood taken for malaria blood films and P. falciparum DNA polymerase chain reaction (PCR). Following diagnosis, patients were treated with artemether-lumefantrine (Coartem®) and invited to return to the health facility after 28 days for repeat blood film and PCR. All PCR P. falciparum positive samples were analysed for molecular markers of lumefantrine and chloroquine resistance. Results Of 49 patients recruited on the basis of a positive rapid diagnostic test, only 16 were confirmed to have P. falciparum by PCR. At follow-up, 14 were PCR-negative for malaria, one was lost to follow-up and one blood specimen had insufficient blood for a PCR analysis. All 16 with PCR-confirmed malaria carried a single copy of the multi-drug resistant (mdr1) gene, and the wild type asparagine allele mdr1 codon 86 (mdr1 86N). Ten of the 16 samples carried the wild type haplotype (CVMNK) at codons 72-76 of the chloroquine resistance transporter gene (pfcrt); three samples carried the resistant CVIET allele; one carried both the resistant and wild type, and in two samples the allele could not be analysed. Conclusions The absence of mdr1 gene copy number variation detected in this study suggests lumefantrine

  10. [The role of intestine in detoxification].

    PubMed

    Chodorowski, Zygmunt; Sein Anand, Jacek; Rybakowska, Iwona; Klimek, Jerzy; Kaletha, Krystian

    2007-01-01

    In the result of liver detoxification, xenobiotics change into more water soluble and thus easier for excretion from the body. It is convenient to consider this process as occurring in two phases. In phase I, the major reactions involved are hydroxylation, catalyzed by monoxygenases. In phase II, the preliminary modified xenobiotics after conjugation with some specific metabolites are transformed into less toxic and more soluble end-products. Recently, antiporter activity of MDR1 (MultiDrug Resistence) gene products in enterocytes was recognized as important stage in detoxification of xenobiotics, and definied as phase III of this process.

  11. [11C]Flumazenil brain uptake is influenced by the blood-brain barrier efflux transporter P-glycoprotein

    PubMed Central

    2012-01-01

    Background [11C]Flumazenil and positron emission tomography (PET) are used clinically to assess gamma-aminobutyric acid (GABA)-ergic function and to localize epileptic foci prior to resective surgery. Enhanced P-glycoprotein (P-gp) activity has been reported in epilepsy and this may confound interpretation of clinical scans if [11C]flumazenil is a P-gp substrate. The purpose of this study was to investigate whether [11C]flumazenil is a P-gp substrate. Methods [11C]Flumazenil PET scans were performed in wild type (WT) (n = 9) and Mdr1a/1b, (the genes that encode for P-gp) double knockout (dKO) (n = 10) mice, and in naive rats (n = 10). In parallel to PET scanning, [11C]flumazenil plasma concentrations were measured in rats. For 6 of the WT and 6 of the dKO mice a second, [11C]flumazenil scan was acquired after administration of the P-gp inhibitor tariquidar. Cerebral [11C]flumazenil concentrations in WT and Mdr1a/1b dKO mice were compared (genetic disruption model). Furthermore, pre and post P-gp-blocking cerebral [11C]flumazenil concentrations were compared in all animals (pharmacological inhibition model). Results Mdr1a/1b dKO mice had approximately 70% higher [11C]flumazenil uptake in the brain than WT mice. After administration of tariquidar, cerebral [11C]flumazenil uptake in WT mice increased by about 80% in WT mice, while it remained the same in Mdr1a/1b dKO mice. In rats, cerebral [11C]flumazenil uptake increased by about 60% after tariquidar administration. Tariquidar had only a small effect on plasma clearance of flumazenil. Conclusions The present study showed that [11C]flumazenil is a P-gp substrate in rodents. Consequently, altered cerebral [11C]flumazenil uptake, as observed in epilepsy, may not reflect solely GABAA receptor density changes but also changes in P-gp activity. PMID:22455873

  12. Multidrug resistance P-glycoprotein dampens SR-BI cholesteryl ester uptake from high density lipoproteins in human leukemia cells.

    PubMed

    Spolitu, Stefano; Uda, Sabrina; Deligia, Stefania; Frau, Alessandra; Collu, Maria; Angius, Fabrizio; Batetta, Barbara

    2016-01-01

    Tumor cells are characterised by a high content of cholesterol esters (CEs), while tumor-bearing patients show low levels of high-density lipoproteins (HDLs). The origin and significance of high CE levels in cancer cell biology has not been completely clarified. Recent evidence that lymphoblastic cells selectively acquire exogenous CE from HDL via the scavenger receptor SR-BI has drawn attention to the additional membrane proteins involved in this pathway. P-glycopotein-MDR1 (P-gp) is a product of the MDR1 gene and confers resistance to antitumor drugs. Its possible role in plasma membrane cholesterol trafficking and CE metabolism has been suggested. In the present study this aspect was investigated in a lymphoblastic cell line selected for MDR1 resistance. CEM were made resistant by stepwise exposure to low (LR) and high (HR) doses of vincristine (VCR). P-gp activity ((3)H-vinblastine), CE content, CE and triglycerides (TG) synthesis ((14)C-oleate), neutral lipids and Dil-HDL uptake (fluorescence), SR-BI, ABCA1 and P-gp protein expression (western blotting) were determined. To better evaluate the relationship between CE metabolism and P-gp activity, the ACAT inhibitor Sandoz-58035 and the P-gp inhibitors progesterone, cyclosporine and verapamil were used. CE content and synthesis were similar in the parental and resistant cells. However, in the latter population, SR-BI protein expression increased, whereas CE-HDL uptake decreased. These changes correlated with the degree of VCR-resistance. As well as reverting MDR1-resistance, the inhibitors of P-gp activity induced the CE-HDL/SR-BI pathway by reactivating membrane cholesterol trafficking. Indeed, CE-HDL uptake, SRBI expression and CE content increased, whereas there was a decrease in cholesterol esterification. These results demonstrated that P-gp overexpression impairs anticancer drug uptake as well as the SR-BI mediated selective CE-HDL uptake. This suggests that these membrane proteins act in an opposite

  13. [Investigation of mutations in transcription factors of efflux pump genes in fluconazole-resistant Candida albicans strains overexpressing the efflux pumps].

    PubMed

    Kalkandelen, Kemal Turan; Doluca Dereli, Mine

    2015-10-01

    In recent years, a significant rise in the number of immunocompromised patients have been observed due to cancer chemotherapy, organ transplantation and HIV infection. As a result of this, the frequency of Candida albicans infections in the clinics have been increased. Fluconazole, as being a well tolerated, easy to use drug with minor side effects, is often the first choice antifungal agent for this patient group, both for therapy and prophylaxis. Especially the long-term use of this drug, causes the selection of resistant strains and leads to the development of fluconazole resistance. The most frequently observed resistance mechanism against fluconazole in C.albicans strains is the transportation of the drug out of the cell via efflux pumps. The efflux pumps mainly involved are Cdr1, Cdr2 ve Mdr1 encoded by CDR1, CDR2 and MDR1 genes. It has been shown that, the overexpression of these efflux pump genes was caused by functional mutations in TAC1 and MRR1 genes which encode the transcription factors Tac1p and Mrr1p. This study was aimed to analyze TAC1 and MRR1 genes of 15 C.albicans strains which consist of six fluconazole-susceptible, four susceptible with trailing effect and five fluconazole-resistant isolates plus one resistant strain (DSY292), known to overexpress Mdr1 efflux pump due to P683H mutation in MRR1 gene and one fluconazole-sensitive ATCC 14053 C.albicans strain in terms of mutations with polymerase chain reaction and sequence analysis. Two of the fluconazole-resistant isolates which had overexpression of Cdr1 and Cdr2 pumps known to have overexpression of TAC1 gene, revealed R673Q and A736V mutations. A P683H point mutation, that overexpressed the Mdr1 pump was detected in a fluconazole-resistant strain, which was known to cause MRR1 overexpression. In conclusion, mutations in the transcription factors of the efflux pump genes may play an important role in the resistance against fluconazole among our selected C.albicans strains. PMID:26649419

  14. [Investigation of mutations in transcription factors of efflux pump genes in fluconazole-resistant Candida albicans strains overexpressing the efflux pumps].

    PubMed

    Kalkandelen, Kemal Turan; Doluca Dereli, Mine

    2015-10-01

    In recent years, a significant rise in the number of immunocompromised patients have been observed due to cancer chemotherapy, organ transplantation and HIV infection. As a result of this, the frequency of Candida albicans infections in the clinics have been increased. Fluconazole, as being a well tolerated, easy to use drug with minor side effects, is often the first choice antifungal agent for this patient group, both for therapy and prophylaxis. Especially the long-term use of this drug, causes the selection of resistant strains and leads to the development of fluconazole resistance. The most frequently observed resistance mechanism against fluconazole in C.albicans strains is the transportation of the drug out of the cell via efflux pumps. The efflux pumps mainly involved are Cdr1, Cdr2 ve Mdr1 encoded by CDR1, CDR2 and MDR1 genes. It has been shown that, the overexpression of these efflux pump genes was caused by functional mutations in TAC1 and MRR1 genes which encode the transcription factors Tac1p and Mrr1p. This study was aimed to analyze TAC1 and MRR1 genes of 15 C.albicans strains which consist of six fluconazole-susceptible, four susceptible with trailing effect and five fluconazole-resistant isolates plus one resistant strain (DSY292), known to overexpress Mdr1 efflux pump due to P683H mutation in MRR1 gene and one fluconazole-sensitive ATCC 14053 C.albicans strain in terms of mutations with polymerase chain reaction and sequence analysis. Two of the fluconazole-resistant isolates which had overexpression of Cdr1 and Cdr2 pumps known to have overexpression of TAC1 gene, revealed R673Q and A736V mutations. A P683H point mutation, that overexpressed the Mdr1 pump was detected in a fluconazole-resistant strain, which was known to cause MRR1 overexpression. In conclusion, mutations in the transcription factors of the efflux pump genes may play an important role in the resistance against fluconazole among our selected C.albicans strains.

  15. Chemoresistance of CD133{sup +} colon cancer may be related with increased survivin expression

    SciTech Connect

    Lee, Mi-Ra; Ji, Sun-Young; Mia-Jan, Khalilullah; Cho, Mee-Yon

    2015-07-31

    CD133, putative cancer stem cell marker, deemed to aid chemoresistance. However, this claim has been challenged recently and we previously reported that patients with CD133{sup +} colon cancer have benefit from 5-fluorouracil (5-FU) chemotherapy incontrast to no benefit in patients with CD133{sup −} cancer. To elucidate the role of CD133 expression in chemoresistance, we silenced the CD133 expression in a colon cancer cell line and determined its effect on the biological characteristics downstream. We comparatively analyzed the sequential changes of MDR1, ABCG2, AKT1 and survivin expression and the result of proliferation assay (WST-1 assay) with 5-FU treatment in CD133{sup +} and siRNA-induced CD133{sup −} cells, derived from Caco-2 colon cancer cell line. 5-FU treatment induced significantly increase of the mRNA expression of MDR1, ABCG2 and AKT1genes, but not protein level. CD133 had little to no effect on the mRNA and protein expression of these genes. However, survivin expression at mRNA and protein level were significantly increased in CD133{sup +} cells compared with siRNA-induced CD133-cells and Mock (not sorted CD133{sup +} cells) at 96 h after siRNA transfection. The cytotoxicity assay demonstrated notable increase of chemoresistance to 5-FU treatment (10 μM) in CD133{sup +} cells at 96 h after siRNA transfection. From this study, we conclude that CD133{sup +} cells may have chemoresistance to 5-FU through the mechanism which is related with survivin expression, instead of MDR1, ABCG2 and AKT1 expression. Therefore a survivin inhibitor can be a new target for effective treatment of CD133{sup +} colon cancer. - Highlights: • We evaluate the role of CD133 in chemoresistance of colon cancer. • We compared the chemoresistance of CD133{sup +} cells and siRNA-induced CD133{sup −} cells. • CD133 had little to no effect on MDR1, ABCG2 and AKT1 expression. • Survivin expression and chemoresistance were increased in CD133{sup +} colon cancer cells.

  16. Antiproliferative amaryllidaceae alkaloids isolated from the bulbs of Sprekelia formosissima and Hymenocallis x festalis.

    PubMed

    Hohmann, Judit; Forgo, Peter; Molnár, Joseph; Wolfard, Krisztina; Molnár, Annamária; Thalhammer, Theresia; Máthé, Imre; Sharples, Derek

    2002-05-01

    Seven alkaloids were isolated from Sprekelia formosissima, and five from Hymenocallis x festalis. Tazettine, lycorine, haemanthidine and haemanthamine were evaluated for antiproliferative and multidrug resistance (mdr) reversing activity on mouse lymphoma cells. Lycorine, haemanthidine and haemanthamine displayed pronounced cell growth inhibitory activities against both drug-sensitive and drug-resistant cell lines, but did not significantly inhibit mdr-1 p-glycoprotein. Thus, the tested alkaloids are apparently not substrates for the mdr efflux pump. Assays for interactions with DNA and RNA revealed that the antiproliferative effects of lycorine and haemanthamine result from their complex formation with RNA.

  17. Probenecid Sensitizes Neuroblastoma Cancer Stem Cells to Cisplatin.

    PubMed

    Campos-Arroyo, Denise; Maldonado, Vilma; Bahena, Ivan; Quintanar, Valeria; Patiño, Nelly; Carlos Martinez-Lazcano, Juan; Melendez-Zajgla, Jorge

    2016-01-01

    We used both in vitro cultures of neuroblastoma cell lines and nude-mice xenotransplants to explore the effects of co-administration of cisplatin and probenecid. Probenecid sensitized neuroblastoma cells, including tumor cells with stem features, to the effects of cisplatin, both in vitro and in vivo. This effect was mediated by an increase in the apoptotic cell death and a concomitant decrease in cell proliferation. This effect is accompanied by modulation of the mRNA and protein of the drug efflux transporters MDR1, MRP2, and BCRP. The co-administration of probenecid with cisplatin should be explored as a possible therapeutic strategy. PMID:26963048

  18. [Antibibiotic resistance by nosocomial infections' causal agents].

    PubMed

    Salazar-Holguín, Héctor Daniel; Cisneros-Robledo, María Elena

    2016-01-01

    Introducción: la resistencia a antimicrobianos por agentes causales de infección nosocomial (IN) constituye un grave problemática global que involucra al HGR 1 del IMSS en Chihuahua, México; si bien con particularidades que requirieron especificarla y evaluarla, a fin de concretar una terapéutica eficaz. Métodos: estudio observacional, descriptivo y prospectivo; se llevó a cabo mediante vigilancia activa durante 2014 para la detección de infecciones nosocomiales, su estudio epidemiológico, cultivo y antibiograma para identificar al agente causal y su resistencia a los antibióticos. Resultados: de 13527 egresos hospitalarios, 1079 presentaron IN (8 por 100 egresos) y de ellas destacaron: de líneas vasculares, quirúrgicas, neumonía y de vías urinarias; sumando dos tercios del total. Se realizó cultivo y antibiograma en 300 de ellas (27.8 %); identificando 31 especies bacterianas, siendo siete las principales (77.9 %): Escherichia coli, Staphylococcus aureus y epidermidis, Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae y Enterobacter cloacae; mostrando multirresistencia a 34 antibióticos probados, excepto en siete con baja o nula resistencia: vancomicina, teicoplanina, linezolid, quinupristina-dalfopristina, piperacilina–tazobactam, amikacina y carbapenémicos. Conclusiones: al contrastar tales resultados ante las recomendaciones de las guías de práctica clínica, surgieron contradicciones; por lo que deben tomarse con reserva y ser probadas en cada hospital, mediante cultivos y antibiogramas en prácticamente todos los casos de infección nosocomial.

  19. 78 FR 21495 - Unblocking of Specially Designated Nationals and Blocked Persons Pursuant To Executive Order 12978

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-10

    .... 1701-1706) (``IEEPA''), issued Executive Order 12978 (60 FR 54579, October 24, 1995) (the ``Order... PLASTICOS CONDOR LTDA., Cali, Colombia; c/o LABORATORIOS KRESSFOR DE COLOMBIA S.A., Bogota, Colombia; c/o... REPRESENTACIONES S.A., Quito, Ecuador; c/o DISTRIBUIDORA DE DROGAS CONDOR LTDA., Bogota, Colombia;...

  20. What You Need to Know About Drugs: Heroin

    MedlinePlus

    ... Recipes What You Need to Know About Drugs: Heroin KidsHealth > For Kids > What You Need to Know About Drugs: Heroin Print A A A Text Size en español ... sobre las drogas: La heroína What It Is: Heroin (say: HAIR-uh-win) comes from the opium ...

  1. Comparison of in vitro cell models in predicting in vivo brain entry of drugs.

    PubMed

    Hakkarainen, Jenni J; Jalkanen, Aaro J; Kääriäinen, Tiina M; Keski-Rahkonen, Pekka; Venäläinen, Tetta; Hokkanen, Juho; Mönkkönen, Jukka; Suhonen, Marjukka; Forsberg, Markus M

    2010-12-15

    Although several in vitro models have been reported to predict the ability of drug candidates to cross the blood-brain barrier, their real in vivo relevance has rarely been evaluated. The present study demonstrates the in vivo relevance of simple unidirectional permeability coefficient (P(app)) determined in three in vitro cell models (BBMEC, Caco-2 and MDCKII-MDR1) for nine model drugs (alprenolol, atenolol, metoprolol, pindolol, entacapone, tolcapone, baclofen, midazolam and ondansetron) by using dual probe microdialysis in the rat brain and blood as an in vivo measure. There was a clear correlation between the P(app) and the unbound brain/blood ratios determined by in vivo microdialysis (BBMEC r=0.99, Caco-2 r=0.91 and MDCKII-MDR1 r=0.85). Despite of the substantial differences in the absolute in vitro P(app) values and regardless of the method used (side-by-side vs. filter insert system), the capability of the in vitro models to rank order drugs was similar. By this approach, thus, the additional value offered by the true endothelial cell model (BBMEC) remains obscure. The present results also highlight the need of both in vitro as well as in vivo methods in characterization of blood-brain barrier passage of new drug candidates.

  2. ERCC1 C118T associates with response to FOLFOX4 chemotherapy in colorectal cancer patients in Han Chinese

    PubMed Central

    Chai, Haina; Pan, Jie; Zhang, Xuelin; Zhang, Xiaoyan; Shen, Xiaoying; Li, Hang; Zhang, Kehao; Yang, Changqing; Sheng, Haihui; Gao, Hengjun

    2012-01-01

    Background Genetic variations influence treatment outcomes in cancer patients treated with chemotherapy. Detection of pharmacogenetic markers associated with treatment response may enable doctor to plan more precise and effective treatment tailoring to individual cancer patients. Methods A novel oligonucleotide microarray was developed to genotype 13 variations (DPYD*2, DPYD*5, DPYD*9, TYMS 6 bp Ins/Del, UGT1A1*6, UGT1A1*27, UGT1A1*28, GSTP1 Ile105Val, XRCC1 Arg399Gln, MTHFR C677T, MDR1 C3435T/A, MDR1 G2677A/T and ERCC1 C118T). The accuracy of genotypes obtained by microarray was assessed by independent sequencing. 73 patients first diagnosed with colorectal cancer (CRC) were treated with FOLFOX4 chemotherapy. Results All genotypes were successfully called by microarray, and were consistent with those identified by independent sequencing except two TYMS 6 bp Ins/Del genotypes. Patients with CT or TT genotype exhibited a higher probability of response to treatment than those with CC genotype. No other SNP was found to be associated with treatment response. Furthermore, these SNPs showed no associations with gastrointestinal, hematological or neurological toxicity. Conclusions ERCC1 C118T may be a predictive marker of treatment response to 5-FU/platinum chemotherapy for CRC. The microarray can significantly facilitate the process of detecting genetic variations and may help doctor plan more effective medication for individual cancer patient. PMID:22567180

  3. The function of the ATP-binding cassette (ABC) transporter ABCB1 is not susceptible to actin disruption.

    PubMed

    Meszaros, Peter; Hummel, Ina; Klappe, Karin; Draghiciu, Oana; Hoekstra, Dick; Kok, Jan W

    2013-02-01

    Previously we have shown that the activity of the multidrug transporter ABCC1 (multidrug resistance protein 1), and its localization in lipid rafts, depends on cortical actin (Hummel I, Klappe K, Ercan C, Kok JW. Mol. Pharm. 2011 79, 229-40). Here we show that the efflux activity of the ATP-binding cassette (ABC) family member ABCB1 (P-glycoprotein), did not depend on actin, neither in ABCB1 over expressing murine National Institutes of Health (NIH) 3T3 MDR1 G185 cells nor in human SK-N-FI cells, which endogenously express ABCB1. Disruption of the actin cytoskeleton, upon treatment of the cells with latrunculin B or cytochalasin D, caused severe changes in cell and membrane morphology, and concomitant changes in the subcellular distribution of ABCB1, as revealed by confocal laser scanning and electron microscopy. Nevertheless, irrespective of actin perturbation, the cell surface pool of ABCB1 remained unaltered. In NIH 3T3 MDR1 G185 cells, ABCB1 is partly localized in detergent-free lipid rafts, which partitioned in two different density gradient regions, both enriched in cholesterol and sphingolipids. Interestingly, disruption of the actin cytoskeleton did not change the density gradient distribution of ABCB1. Our data demonstrate that the functioning of ABCB1 as an efflux pump does not depend on actin, which is due to its distribution in both cell surface-localized non-raft membrane areas and lipid raft domains, which do not depend on actin stabilization.

  4. Bicistronic retroviral vectors for combining myeloprotection with cell-surface marking.

    PubMed

    Hildinger, M; Schilz, A; Eckert, H G; Bohn, W; Fehse, B; Zander, A; Ostertag, W; Baum, C

    1999-07-01

    We have developed a retroviral vector coexpressing the multidrug-resistance 1 (MDR1) cDNA for inducing cancer drug resistance and the truncated version of the low-affinity nerve growth factor receptor (DeltaLNGFR) for cell-surface marking of transduced cells. The vector is based on the FMEV backbone which mediates high levels of gene expression in hematopoietic cells. To achieve optimal expression levels of both cDNAs, untranslated regions from MDR1 and DeltaLNGFR were removed and three different connections were tested: retroviral splice signals, an internal ribosomal entry site (IRES) from encephalomyocarditis virus, and an internal promoter from the chicken beta-actin gene. As determined by two-color flow cytometry, the best correlation of the expression of both cDNAs was obtained using the vector SF1mSdelta which utilized retroviral splice signals for co-expression. Simultaneous expression of both cDNAs at the single cell level was also shown by confocal laser microscopy. Lymphoid and hematopoietic progenitor cells, including primary human CD34+ cells, transduced with SF1mSdelta acquired dominant multidrug resistance. Transduced primary CD34+ cells could be enriched in vitro based on expression of DeltaLNGFR, avoiding exposure to cytostatic agents. Thus, monitoring the selection of chemotherapy-resistant cells and analyzing their biological properties may be alleviated, both in vitro and in vivo. PMID:10455430

  5. Influences of "spasmolytic powder" on pgp expression of Coriaria Lactone-kindling drug-resistant epileptic rat model.

    PubMed

    Chen, Lei; Feng, Peimin; Li, Yaohua; Zhou, Dong

    2013-09-01

    The earliest records of traditional Chinese medicine (TCM) prevention and treatment of epilepsy dated back to famous "Huang Di Nei Jing." TCM "spasmolytic powder" (equal-ratio compatibility of scorpion and centipede) is a famous prescription which was recognized as a useful add-on drug for refractory epilepsy in clinical observations. Multidrug resistance gene (mdr1) product Pgp overexpression in blood-brain barrier and blood-cerebrospinal fluid barrier is well recognized as the drug resistance mechanism of refractory epilepsy. Here, we established the drug-resistant epilepsy Sprague-Dawley rat model induced by Coriaria Lactone and treated these rats with topiramate and verapamil and low dose, middle dose, and high dose of spasmolytic powder by intragastric administration for 1 week. Electroencephalogram, real-time PCR, and immunohistochemistry were respectively used to detect epileptic discharge frequencies and amplitudes and expression of mdrl mRNA and Pgp on hippocampus and temporal lobe of rats. The results showed that the seizure decreases significantly in the high- and middle-dose groups of spasmolytic powder and topiramate group; in addition, mdr1 mRNA and Pgp expressions on hippocampus and temporal lobe of these drug intervention groups were significantly less than the model group (P < 0.05). These findings indicate that inhibition of intracephalic Pgp expression is possibly one of mechanisms of spasmolytic powder treating refractory epilepsy.

  6. Design, synthesis, and biological evaluation of a novel series of peripheral-selective noradrenaline reuptake inhibitors - Part 3.

    PubMed

    Yukawa, Tomoya; Nakada, Yoshihisa; Sakauchi, Nobuki; Kamei, Taku; Yamada, Masami; Ohba, Yusuke; Fujimori, Ikuo; Ueno, Hiroyuki; Takiguchi, Maiko; Kuno, Masako; Kamo, Izumi; Nakagawa, Hideyuki; Fujioka, Yasushi; Igari, Tomoko; Ishichi, Yuji; Tsukamoto, Tetsuya

    2016-08-15

    Peripheral-selective inhibition of noradrenaline reuptake is a novel mechanism for the treatment of stress urinary incontinence to overcome adverse effects associated with central action. Here, we describe our medicinal chemistry approach to discover a novel series of highly potent, peripheral-selective, and orally available noradrenaline reuptake inhibitors with a low multidrug resistance protein 1 (MDR1) efflux ratio by cyclization of an amide moiety and introduction of an acidic group. We observed that the MDR1 efflux ratio was correlated with the pKa value of the acidic moiety. The resulting compound 9 exhibited favorable PK profiles, probably because of the effect of intramolecular hydrogen bond, which was supported by a its single-crystal structure. The compound 9, 1-{[(6S,7R)-7-(4-chloro-3-fluorophenyl)-1,4-oxazepan-6-yl]methyl}-2-oxo-1,2-dihydropyridine-3-carboxylic acid hydrochloride, which exhibited peripheral NET-selective inhibition at tested doses in rats by oral administration, increased urethral resistance in a dose-dependent manner. PMID:27325446

  7. Murine Norovirus: An Intercurrent Variable in a Mouse Model of Bacteria-Induced Inflammatory Bowel Disease

    PubMed Central

    Lencioni, Karen Chase; Seamons, Audrey; Treuting, Piper M; Maggio-Price, Lillian; Brabb, Thea

    2008-01-01

    Murine norovirus (MNV) has recently been recognized as a widely prevalent viral pathogen in mouse colonies and causes disease and mortality in mice with impaired innate immunity. We tested the hypothesis that MNV infection would alter disease course and immune responses in mice with inflammatory bowel disease (IBD). FVB.129P2-Abcb1atm1Bor N7 (Mdr1a−/−) mice develop spontaneous IBD that is accelerated by infection with Helicobacter bilis. As compared with controls, Mdr1a−/− mice coinfected with MNV4 and H. bilis showed greater weight loss and IBD scores indicative of severe colitis, demonstrating that MNV4 can modulate the progression of IBD. Compared with controls, mice inoculated with MNV4 alone had altered levels of serum biomarkers, and flow cytometric analysis of immune cells from MNV4-infected mice showed changes in both dendritic cell (CD11c+) and other nonT cell (CD4− CD8−) populations. Dendritic cells isolated from MNV4-infected mice induced higher IFNγ production by polyclonal T cells in vitro at 2 d after infection but not at later time points, indicating that MNV4 infection enhances antigen presentation by dendritic cells early after acute infection. These findings indicate that acute infection with MNV4 is immunomodulatory and alters disease progression in a mouse model of IBD. PMID:19149409

  8. Increased intestinal P-glycoprotein expression and activity with progression of diabetes and its modulation by epigallocatechin-3-gallate: Evidence from pharmacokinetic studies.

    PubMed

    Dash, Ranjeet Prasad; Ellendula, Bhanuchander; Agarwal, Milee; Nivsarkar, Manish

    2015-11-15

    The aim of this study was to evaluate the change in the expression and the activity of intestinal P-glycoprotein (efflux transporter) with progression of diabetes in rats. Diabetes was induced in Wistar rats using a combination of low dose streptozotocin along with high fat diet. The expression of intestinal P-glycoprotein significantly increased (P≤0.05) with the progression of diabetes which was inferred from the mRNA analysis of mdr1a and mdr1b genes in the ileum segment of rat intestine. Furthermore, a significant increase (P≤0.05) in Na(+)-K(+) ATPase activity was observed in the ileum segment of rat intestine with the progression of diabetes. As a result of this, a significant decrease in the intestinal uptake and peroral bioavailability of the P-glycoprotein substrates (verapamil and atorvastatin) was observed along with the progression of diabetes as compared to normal animals. To address this problem of impaired drug uptake and bioavailability, a reported P-glycoprotein inhibitor, epigallocatechin-3-gallate, was experimentally evaluated. The treatment with epigallocatechin-3-gallate resulted in significant reduction in the expression and activity of P-glycoprotein and subsequent improvement in the intestinal uptake and peroral bioavailability of both verapamil and atorvastatin in normal as well as in diabetic animals. The findings of this study rationalised the use and established the mechanism of action of epigallocatechin-3-gallate to overcome P-glycoprotein mediated drug efflux and will also be helpful in therapeutic drug monitoring in diabetes.

  9. The multixenobiotic resistance mechanism in aquatic organisms

    SciTech Connect

    Kurelec, B. )

    1992-01-01

    Many aquatic organisms thrive and reproduce in polluted waters. This fact indicates that they are well equipped with a defense system(s) against several toxic xenobiotics simultaneously because water pollution is typically caused by a mixture of a number of pollutants. We have found that the biochemical mechanism underlying such multixenobiotic' resistance in freshwater and marine mussel, in several marine sponges, and in freshwater fish is similar to the mechanism of multidrug resistance (MDR) found in tumor cells that became refractory to treatment with a variety of chemotherapeutic agents. All these organisms possess a verapamil-sensitive potential to bind 2-acetylaminofluorene and vincristine onto membrane vesicles. They all express mRNA for mdr1 gene, and mdr1 protein product, the glycoprotein P170. Finally, in in vivo experiments, the accumulation of xenobiotics is enhanced in all investigated organisms in the presence of verapamil, the inhibitor of the P170 extrusion pump. The knowledge that the presence of one xenobiotic may block the pumping out, and hence accelerating accumulation, of others, may help us to understand and interpret our present and past data on different environmental parameters obtained using indicator organisms.99 references.

  10. Glucose deprivation induces chemoresistance in colorectal cancer cells by increasing ATF4 expression

    PubMed Central

    Hu, Ya-Ling; Yin, Yuan; Liu, He-Yong; Feng, Yu-Yang; Bian, Ze-Hua; Zhou, Le-Yuan; Zhang, Ji-Wei; Fei, Bo-Jian; Wang, Yu-Gang; Huang, Zhao-Hui

    2016-01-01

    AIM: To investigate the role of activating transcription factor 4 (ATF4) in glucose deprivation (GD) induced colorectal cancer (CRC) drug resistance and the mechanism involved. METHODS: Chemosensitivity and apoptosis were measured under the GD condition. Inhibition of ATF4 using short hairpin RNA in CRC cells under the GD condition and in ATF4-overexpressing CRC cells was performed to identify the role of ATF4 in the GD induced chemoresistance. Quantitative real-time RT-PCR and Western blot were used to detect the mRNA and protein expression of drug resistance gene 1 (MDR1), respectively. RESULTS: GD protected CRC cells from drug-induced apoptosis (oxaliplatin and 5-fluorouracil) and induced the expression of ATF4, a key gene of the unfolded protein response. Depletion of ATF4 in CRC cells under the GD condition can induce apoptosis and drug re-sensitization. Similarly, inhibition of ATF4 in the ATF4-overexpressing CRC cells reintroduced therapeutic sensitivity and apoptosis. In addition, increased MDR1 expression was observed in GD-treated CRC cells. CONCLUSION: These data indicate that GD promotes chemoresistance in CRC cells through up-regulating ATF4 expression. PMID:27468213

  11. The role of ABC transporters in drug resistance, metabolism and toxicity.

    PubMed

    Glavinas, Hristos; Krajcsi, Péter; Cserepes, Judit; Sarkadi, Balázs

    2004-01-01

    ATP Binding Cassette (ABC) transporters form a special family of membrane proteins, characterized by homologous ATP-binding, and large, multispanning transmembrane domains. Several members of this family are primary active transporters, which significantly modulate the absorption, metabolism, cellular effectivity and toxicity of pharmacological agents. This review provides a general overview of the human ABC transporters, their expression, localization and basic mechanism of action. Then we shortly deal with the human ABC transporters as targets of therapeutic interventions in medicine, including cancer drug resistance, lipid and other metabolic disorders, and even gene therapy applications. We place a special emphasis on the three major groups of ABC transporters involved in cancer multidrug resistance (MDR). These are the classical P-glycoprotein (MDR1, ABCB1), the multidrug resistance associated proteins (MRPs, in the ABCC subfamily), and the ABCG2 protein, an ABC half-transporter. All these proteins catalyze an ATP-dependent active transport of chemically unrelated compounds, including anticancer drugs. MDR1 (P-glycoprotein) and ABCG2 preferentially extrude large hydrophobic, positively charged molecules, while the members of the MRP family can extrude both hydrophobic uncharged molecules and water-soluble anionic compounds. Based on the physiological expression and role of these transporters, we provide examples for their role in Absorption-Distribution-Metabolism-Excretion (ADME) and toxicology, and describe several basic assays which can be applied for screening drug interactions with ABC transporters in the course of drug research and development.

  12. Synthesis and small-animal positron emission tomography evaluation of [11C]-elacridar as a radiotracer to assess the distribution of P-glycoprotein at the blood-brain barrier

    PubMed Central

    Dörner, Bernd; Kuntner, Claudia; Bankstahl, Jens P.; Bankstahl, Marion; Stanek, Johann; Wanek, Thomas; Stundner, Gloria; Mairinger, Severin; Löscher, Wolfgang; Müller, Markus; Langer, Oliver; Erker, Thomas

    2013-01-01

    With the aim to develop a positron emission tomography (PET) tracer to assess the distribution of P-glycoprotein (P-gp) at the blood-brain barrier (BBB) in vivo, the potent third-generation P-gp inhibitor elacridar (1) was labeled with 11C by reaction of O-desmethyl 1 with [11C]-methyl triflate. In vitro autoradiography and small-animal PET imaging of [11C]-1 was performed in rats (n=3), before and after administration of unlabeled 1, as well as in wild-type, Mdr1a/b(−/−) and Bcrp1(−/−) mice (n=3). In PET experiments in rats, administration of unlabeled 1 increased brain activity uptake 5.4-fold, whereas blood activity levels remained unchanged. In Mdr1a/b(−/−) mice, brain activity uptake was 2.5-fold higher compared to wild-type animals, whereas in Bcrp1(−/−) mice brain activity uptake was only 1.3-fold higher. In vitro autoradiography showed that 63% of [11C]-1 binding was displaceable by an excess of unlabeled 1. As the signal obtained with [11C]-1 appeared to be specific for P-gp at the BBB, its utility for the visualization of cerebral P-gp merits further investigation. PMID:19711894

  13. [Reversal effect of cinobufacini on multidrug resistance of Raji/ADR cells and its mechanisms].

    PubMed

    Zhang, Cheng; Wan, Ding-Ming; Cao, Wei-Jie

    2014-10-01

    The aim of this study was to explore the reversing effect of cinobufacini on multidrug resistance of Raji/ADR cells and its mechanisms. The growth inhibitory rate, half inhibitory concentration (IC50), reversing multiples to adriamycin- resistance were detected by MTT, and the curve of growth inhibitory rate was drawn; the MDR-1 and MRP-1 gene transcription was determined by RT-PCR; the expressions of P-gp and MRP-1 proteins were assayed by Western blot and flow cytometry. The results showed that the inhibitory rates of cinobufacini on Raji and Raji/ADR cells at 72 h were 75.6% and 69.3% respectively, the IC50 were 3.9 mmol/L and 4.6 mmol/L without significant difference (P > 0.05). The reversing multiples to adriamycin-resistance were 255.7 multiples, the transcription of mdr-1 and mrp-1 genes and the expression of P-gp and MRP-1 proteins significantly decreased (P < 0.05) in Raji/ADR cells after the treatment with cinobufotalin. It is concluded that cinobufotalin can reverse the adriamycin-resistance in Raji/ADR cells and the expression of P-gp and MRP-1 proteins were down-regulated through the transcriptional pathway. The cinobufotalin is an effective reversal agent for the multidrug resistance of tumors.

  14. Overexpression and mutation as a genetic mechanism of fluconazole resistance in Candida albicans isolated from human immunodeficiency virus patients in Indonesia.

    PubMed

    Rosana, Yeva; Yasmon, Andi; Lestari, Delly Chipta

    2015-09-01

    Fluconazole is the standard treatment for oropharyngeal candidiasis, which is the third most common opportunistic infection in human immunodeficiency virus (HIV)/AIDS patients in Indonesia. Overuse of this drug could lead to the emergence of resistance. The objective of this study was to analyse the role of ERG11, CDR1, CDR2 and MDR1 gene overexpression and mutations in the ERG11 gene as a genetic mechanism of fluconazole resistance in Candida albicans isolated from HIV patients in Indonesia. Overexpression of ERG11, CDR1, CDR2 and MDR1 was analysed by real-time reverse transcription PCR, while ERG11 gene mutation analysis was performed using sequencing methods. Seventeen isolates out of 92 strains of C. albicans isolated from 108 HIV patients were found to be resistant to azole antifungals. The highest gene overexpression of ERG11 was found in C. albicans resistant to single fluconazole, while the highest gene overexpression of CDR2 was detected in all isolates of C. albicans resistant to multiple azoles. Amino acid substitutions were observed at six positions, i.e. D116E, D153E, I261V, E266D, V437I and V488I. The amino acid substitution I261V was identified in this study and was probably associated with fluconazole resistance. The combination of overexpression of CDR2 and ERG11 and mutation in the ERG11 gene was found to be a genetic mechanism of fluconazole resistance in C. albicans isolated from HIV patients in Indonesia.

  15. Distribution characteristics of telithromycin, a novel ketolide antimicrobial agent applied for treatment of respiratory infection, in lung epithelial lining fluid and alveolar macrophages.

    PubMed

    Togami, Kohei; Chono, Sumio; Seki, Toshinobu; Morimoto, Kazuhiro

    2009-01-01

    The distribution characteristics of telithromycin (TEL), a novel ketolide antimicrobial agent, in lung epithelial fluid (ELF) and alveolar macrophages (AMs) were evaluated. In vivo animal experiments, the time-courses of the concentrations of TEL in ELF and AMs following oral administration of TEL solution (50 mg/4 mL/kg) to rats were markedly higher than in plasma, and areas under drug concentration-time curve (AUC) ratios of ELF/plasma and AMs/plasma were 2.4 and 65.3, respectively. In vitro transport experiments, the basolateral-to-apical transport of TEL through model lung epithelial cell (Calu-3) monolayers was greater than apical-to-basolateral transport. Rhodamine123 and verapamil, MDR1 substrates, reduced the basolateral-to-apical transport of TEL. In vitro uptake experiments, the intracellular equilibrated concentration of TEL in cultured AMs (NR8383) was approximately 40 times the extracellular concentration. The uptake of TEL by NR8383 was inhibited by rotenone and FCCP, ATP depletors and was temperature-dependent. These data suggest that the high distribution of TEL to AMs is due to the sustained distribution to ELF via MDR1 as well as the high uptake by AMs themselves via active transport mechanisms.

  16. Distribution characteristics of clarithromycin and azithromycin, macrolide antimicrobial agents used for treatment of respiratory infections, in lung epithelial lining fluid and alveolar macrophages.

    PubMed

    Togami, Kohei; Chono, Sumio; Morimoto, Kazuhiro

    2011-10-01

    The distribution characteristics of clarithromycin (CAM) and azithromycin (AZM), macrolide antimicrobial agents, in lung epithelial lining fluid (ELF) and alveolar macrophages (AMs) were evaluated. In the in vivo animal experiments, the time-courses of the concentrations of CAM and AZM in ELF and AMs following oral administration (50 mg/kg) to rats were markedly higher than those in plasma, and the area under the drug concentration-time curve (AUC) ratios of ELF/plasma of CAM and AZM were 12 and 2.2, and the AUC ratios of AMs/ELF were 37 and 291, respectively. In the in vitro transport experiments, the basolateral-to-apical transport of CAM and AZM through model lung epithelial cell (Calu-3) monolayers were greater than the apical-to-basolateral transport. MDR1 substrates reduced the basolateral-to-apical transport of CAM and AZM. In the in vitro uptake experiments, the intracellular concentrations of CAM and AZM in cultured AMs (NR8383) were greater than the extracellular concentrations. The uptake of CAM and AZM by NR8383 was inhibited by ATP depletors. These data suggest that the high distribution of CAM and AZM to AMs is due to the sustained distribution to ELF via MDR1 as well as the high uptake by the AMs themselves via active transport mechanisms.

  17. Vulvovaginal candidiasis: species distribution, fluconazole resistance and drug efflux pump gene overexpression.

    PubMed

    Zhang, Jie-Yu; Liu, Jin-Hui; Liu, Fa-Di; Xia, Yan-Hua; Wang, Jing; Liu, Xi; Zhang, Zhi-Qin; Zhu, Na; Yan-Yan; Ying, Ying; Huang, Xiao-Tian

    2014-10-01

    The increasing incidence of vulvovaginal candidiasis (VVC) and the emergence of fluconazole resistance are an indisputable fact. However, little information is available regarding the correlation between fluconazole resistance in vaginal Candida albicans and the expression of drug efflux pump genes. In this study, we investigated the species distribution, fluconazole susceptibility profiles and the mechanisms of fluconazole resistance in Candida strains. In total, 785 clinical Candida isolates were collected from patients with VVC. C. albicans was the most frequently isolated species(n = 529) followed by C. glabrata (n = 164) and C. krusei (n = 57). Of all Candida isolates, 4.7% were resistant to fluconazole. We randomly selected 18 fluconazole resistant isolates of C. albicans to evaluate the expression of CDR1, CDR2, MDR1 and FLU1 genes. Compared with fluconazole-susceptible C. albicans isolates, CDR1 gene expression displayed 3.16-fold relative increase, which was statistically significant. CDR2, MDR1 and FLU1 overexpression was observed in several fluconazole-resistant C. albicans isolates, but statistical significance was not achieved. These results demonstrate a high frequency of non-albicans species (32.6%); however, C. albicans is the most common Candida species implicated in vaginitis, and this strain displays considerable fluconazole resistance. Meanwhile, our study further indicates that fluconazole resistance in C. albicans may correlate with CDR1 gene overexpression.

  18. Multidrug Transporters and Alterations in Sterol Biosynthesis Contribute to Azole Antifungal Resistance in Candida parapsilosis.

    PubMed

    Berkow, Elizabeth L; Manigaba, Kayihura; Parker, Josie E; Barker, Katherine S; Kelly, Stephen L; Rogers, P David

    2015-10-01

    While much is known concerning azole resistance in Candida albicans, considerably less is understood about Candida parapsilosis, an emerging species of Candida with clinical relevance. We conducted a comprehensive analysis of azole resistance in a collection of resistant C. parapsilosis clinical isolates in order to determine which genes might play a role in this process within this species. We examined the relative expression of the putative drug transporter genes CDR1 and MDR1 and that of ERG11. In isolates overexpressing these genes, we sequenced the genes encoding their presumed transcriptional regulators, TAC1, MRR1, and UPC2, respectively. We also sequenced the sterol biosynthesis genes ERG3 and ERG11 in these isolates to find mutations that might contribute to this phenotype in this Candida species. Our findings demonstrate that the putative drug transporters Cdr1 and Mdr1 contribute directly to azole resistance and suggest that their overexpression is due to activating mutations in the genes encoding their transcriptional regulators. We also observed that the Y132F substitution in ERG11 is the only substitution occurring exclusively among azole-resistant isolates, and we correlated this with specific changes in sterol biosynthesis. Finally, sterol analysis of these isolates suggests that other changes in sterol biosynthesis may contribute to azole resistance in C. parapsilosis.

  19. Distinct alterations in ATP-binding cassette transporter expression in liver, kidney, small intestine, and brain in adjuvant-induced arthritic rats.

    PubMed

    Kawase, Atsushi; Norikane, Sari; Okada, Ayaka; Adachi, Mamiko; Kato, Yukio; Iwaki, Masahiro

    2014-08-01

    Pathophysiological changes of infection or inflammation are associated with alterations in the production of numerous absorption, distribution, metabolism and excretion-related proteins. However, little information is available on the effects of inflammation on the expression levels and activities of ATP-binding cassette (ABC) transporters. We examined the effect of acute (on day 7) and chronic (on day 21) inflammation on the expression of ABC transporters in some major tissues in rat. Adjuvant-induced arthritis (AA) in rats was used as an animal model for inflammation. The mRNA levels of mdr1a and mdr1b encoding P-glycoprotein (P-gp) decreased significantly in livers of AA rats on day 21. Hepatic protein levels of P-gp, Mrp2, and Bcrp decreased significantly in membranes but not homogenates of AA rats after 7 days and after 21 days of treatment with adjuvant. Contrary to liver, protein levels of P-gp and Mrp2, but not Bcrp in kidney, increased significantly in membranes. The biliary excretion of rhodamine 123 was decreased in rats with chronic inflammation owing to decreases in efflux activities of P-gp. Our results showed that the expression of transporters in response to inflammation was organ dependent. In particular, hepatic and renal P-gp and Mrp2 exhibited opposite changes in membrane protein levels.

  20. Selection of three out of 24 anti-cancer agents in poorly-differentiated gastric cancer cell lines, evaluated by the AUC/delta IC50 ratio.

    PubMed

    Nozue, M; Nishida, M; Todoroki, T; Fukao, K; Tanaka, M

    1995-04-01

    The purpose of this study was to screen 24 anti-cancer drugs, either in use or in clinical study, using four cell lines, all of which originated from poorly-differentiated gastric cancers. The MTT assay was used at 1, 6, 24 or 72 h exposure times as the chemosensitivity test. We also examined P-glycoprotein expression, mdr-1 gene amplification and the modifier effect of verapamil. All four cell lines generally showed the same chemosensitivity pattern, while GCIY cells showed mdr-1 gene amplification and P-glycoprotein expression, and KATOIII cells showed the multidrug resistant pattern without P-glycoprotein expression. Both cell lines acquired higher chemosensitivity after verapamil addition. All IC50 data (with or without verapamil) were multiplied by exposure time (delta IC50) and compared with the clinical 'area under the concentration curve (AUC)'. SN-38 with/without verapamil, cisplatin with verapamil and pirarubicin with/without verapamil seemed to be the best candidates for poorly-differentiated gastric cancer chemotherapy. Plant alkaloids could also be candidates. With further experiments, we may be able to deduce commonly effective chemotherapy for poorly-differentiated gastric cancer from these drugs. PMID:7795277

  1. The Anticancer Agent Prodigiosin Is Not a Multidrug Resistance Protein Substrate

    PubMed Central

    Elahian, Fatemeh; Moghimi, Bahareh; Dinmohammadi, Farideh; Ghamghami, Mahsa; Hamidi, Mehrdad

    2013-01-01

    The brilliant red pigments prodiginines are natural secondary metabolites that are produced by select species of Gram-negative and Gram-positive bacteria. These molecules have received significant attention due to their reported antibacterial, antifungal, immunosuppressive, and anticancer activities. In this study, a Serratia marcescens SER1 strain was isolated and verified using 16s rDNA. The prodigiosin was purified using silica chromatography and was analyzed by 1H-NMR spectroscopy. The cell cytotoxic effects of the purified prodigiosin on multiple drug resistant cell lines that overexpress MDR1, BCRP, or MRP2 pumps were analyzed. Prodigiosin had nearly identical cytotoxic effects on the resistant cells in comparison to their parental lines. In agreement with the same prodigiosin cytotoxicity, FACS analysis of prodigiosin accumulation and efflux in MDR overexpressing cell lines also indicated that this pro-apoptotic agent operates independently of the presence of the MDR1, BCRP, or MRP transporter and may be a potential treatment for malignant cancer cells that overexpress multidrug resistance transporters. PMID:23373476

  2. Inhibition of multixenobiotic resistance transporters (MXR) by silver nanoparticles and ions in vitro and in Daphnia magna.

    PubMed

    Georgantzopoulou, Anastasia; Cambier, Sébastien; Serchi, Tommaso; Kruszewski, Marcin; Balachandran, Yekkuni L; Grysan, Patrick; Audinot, Jean-Nicolas; Ziebel, Johanna; Guignard, Cédric; Gutleb, Arno C; Murk, AlberTinka J

    2016-11-01

    The P-glycoprotein (P-gp, ABCB1) and multidrug resistance associated protein 1 (MRP1), important members of the ABC (ATP-binding cassette) transporters, protect cells and organisms via efflux of xenobiotics and are responsible for the phenomenon of multidrug or multixenobiotic resistance (MXR). In this study we first evaluated, in vitro, the interaction of silver nanoparticles (Ag NPs, 20, 23 and 27nm), Ag 200nm particles and Ag ions (AgNO3) with MXR efflux transporters using MDCKII and the P-gp over-expressing MDCKII-MDR1 cells and calcein-AM as a substrate of the transporters. Next the in vivo modulation of MXR activity was studied in Daphnia magna juveniles with the model P-gp and MRP1 inhibitors verapamil-HCl and MK571, respectively. The common environmental contaminants perfluorooctane sulfonate and bisphenol A, previously observed to interfere with the P-gp in vitro, also inhibited the efflux of calcein in vivo. Small-sized Ag NPs (with biomolecules present on the surface) and AgNO3 inhibited the MXR activity in daphnids and MDCKII-MDR1 cells, but abcb1 gene expression remained unchanged. Both Ag NPs and dissolved ions contributed to the effects. This study provides evidence of the interference of Ag NPs and AgNO3 with the MXR activity both in vitro and in D. magna, and should be taken into account when Ag NP toxicity is assessed. PMID:27376922

  3. Candida albicans and C. tropicalis Isolates from the Expired Breathes of Captive Dolphins and Their Environments in an Aquarium.

    PubMed

    Takahashi, Hideo; Ueda, Keiichi; Itano, Eiko Nakagawa; Yanagisawa, Makio; Murata, Yoshiteru; Murata, Michiko; Yaguchi, Takashi; Murakami, Masaru; Kamei, Katsuhiko; Inomata, Tomo; Miyahara, Hirokazu; Sano, Ayako; Uchida, Senzo

    2010-12-22

    Genotypes of Candida spp. isolated from exhalation of 20 dolphins, 11 water samples from captive pools, and 24 oral cavities of staff members in an aquarium using a combination of multiple drug resistance 1 gene (MDR1) and the internal transcribed spacer (ITS) 1 5.8s-ITS 2 regions of ribosomal RNA gene (ITS rDNA) sequences were studied. The holding ratios of the dolphins, captive pools, and staff members were 70, 90, and 29%, respectively. Isolated pathogenic yeast species common to the dolphins and environments were Candida albicans and C. tropicalis. Identical genotypes in both Candida spp. based on the combination of MDR1 and ITSrDNA were found in some dolphins, between a dolphin and a staff, among dolphins and environments, and among environments. The results indicated the diffusion and exchange of pathogenic yeasts at the aquarium among dolphins and environments. The isolates at the aquarium showed higher rates of resistance to azole antifungals compared to reference isolates.

  4. The anticancer agent prodigiosin is not a multidrug resistance protein substrate.

    PubMed

    Elahian, Fatemeh; Moghimi, Bahareh; Dinmohammadi, Farideh; Ghamghami, Mahsa; Hamidi, Mehrdad; Mirzaei, Seyed Abbas

    2013-03-01

    The brilliant red pigments prodiginines are natural secondary metabolites that are produced by select species of Gram-negative and Gram-positive bacteria. These molecules have received significant attention due to their reported antibacterial, antifungal, immunosuppressive, and anticancer activities. In this study, a Serratia marcescens SER1 strain was isolated and verified using 16s rDNA. The prodigiosin was purified using silica chromatography and was analyzed by (1)H-NMR spectroscopy. The cell cytotoxic effects of the purified prodigiosin on multiple drug resistant cell lines that overexpress MDR1, BCRP, or MRP2 pumps were analyzed. Prodigiosin had nearly identical cytotoxic effects on the resistant cells in comparison to their parental lines. In agreement with the same prodigiosin cytotoxicity, FACS analysis of prodigiosin accumulation and efflux in MDR overexpressing cell lines also indicated that this pro-apoptotic agent operates independently of the presence of the MDR1, BCRP, or MRP transporter and may be a potential treatment for malignant cancer cells that overexpress multidrug resistance transporters.

  5. Drug-induced trafficking of p-glycoprotein in human brain capillary endothelial cells as demonstrated by exposure to mitomycin C.

    PubMed

    Noack, Andreas; Noack, Sandra; Hoffmann, Andrea; Maalouf, Katia; Buettner, Manuela; Couraud, Pierre-Olivier; Romero, Ignacio A; Weksler, Babette; Alms, Dana; Römermann, Kerstin; Naim, Hassan Y; Löscher, Wolfgang

    2014-01-01

    P-glycoprotein (Pgp; ABCB1/MDR1) is a major efflux transporter at the blood-brain barrier (BBB), restricting the penetration of various compounds. In other tissues, trafficking of Pgp from subcellular stores to the cell surface has been demonstrated and may constitute a rapid way of the cell to respond to toxic compounds by functional membrane insertion of the transporter. It is not known whether drug-induced Pgp trafficking also occurs in brain capillary endothelial cells that form the BBB. In this study, trafficking of Pgp was investigated in human brain capillary endothelial cells (hCMEC/D3) that were stably transfected with a doxycycline-inducible MDR1-EGFP fusion plasmid. In the presence of doxycycline, these cells exhibited a 15-fold increase in Pgp-EGFP fusion protein expression, which was associated with an increased efflux of the Pgp substrate rhodamine 123 (Rho123). The chemotherapeutic agent mitomycin C (MMC) was used to study drug-induced trafficking of Pgp. Confocal fluorescence microscopy of single hCMEC/D3-MDR1-EGFP cells revealed that Pgp redistribution from intracellular pools to the cell surface occurred within 2 h of MMC exposure. Pgp-EGFP exhibited a punctuate pattern at the cell surface compatible with concentrated regions of the fusion protein in membrane microdomains, i.e., lipid rafts, which was confirmed by Western blot analysis of biotinylated cell surface proteins in Lubrol-resistant membranes. MMC exposure also increased the functionality of Pgp as assessed in three functional assays with Pgp substrates (Rho123, eFluxx-ID Gold, calcein-AM). However, this increase occurred with some delay after the increased Pgp expression and coincided with the release of Pgp from the Lubrol-resistant membrane complexes. Disrupting rafts by depleting the membrane of cholesterol increased the functionality of Pgp. Our data present the first direct evidence of drug-induced Pgp trafficking at the human BBB and indicate that Pgp has to be released from lipid

  6. New flow cytometric method for detection of minimally expressed multidrug resistance P-glycoprotein on normal and acute leukemia cells using biotinylated MRK16 and streptavidin-RED670 conjugate.

    PubMed

    Takeshita, A; Shinjo, K; Ohnishi, K; Ohno, R

    1995-06-01

    To evaluate the expression of multidrug resistance (MDR) on normal and leukemia cells, we examined P-glycoprotein (P-gp) by a newly devised flow cytometric method, utilizing a biotinylated monoclonal antibody (mAb) against P-gp (MRK16), a streptavidin-RED670 conjugate (SA-RED670) and appropriate emission filters. The combination of biotinylated MRK16 (b-MRK16) and SA-RED670 resulted in higher sensitivity as compared with standard methods such as the use of streptavidin-phycoerythrin (SA-PE) conjugate. The sensitivity was examined in K562, K562/ADR, NOMO-1, NOMO-1/ADR and HL60 cells, and compared with the data obtained from reverse transcription polymerase chain reaction (RT-PCR) of mdr-1 gene. P-gp positivity on flow cytometry was 10.4%, 99.9%, 1.4%, 90.4% and 0%, respectively. Mdr-1 mRNA was well expressed in K562/ADR and NOMO-1/ADR cells, but not in NOMO-1 and HL60 cells. In K562 cells, mdr-1 was found after 40 cycles of PCR, but not 25 cycles. These data are well correlated with those from the flow cytometry. We then studied the P-gp expression on normal peripheral blood cells and acute leukemia cells. P-gp was little expressed on peripheral lymphocytes, monocytes and granulocytes. It was also little expressed on blast cells from 5 patients with acute promyelocytic leukemia (AML) and 5 acute lymphocytic leukemia (ALL) expressed P-gp at diagnosis, ranging from 8.5% to 34.5% (16.9 +/- 11.8%) and from 2.3% to 45.6% (24.0 +/- 17.8%), respectively. All 9 relapsed or refractory cases expressed P-gp, ranging from 21.1% to 99.8% (52.2 +/- 29.9%). Significant differences were found in APL, CD34-positive and relapse and refractory cases (P = 0.0006, 0.0007 and 0.0088, respectively). These results indicate that this flow cytometric analysis is useful for the evaluation of clinical MDR status and can identify a group of patients with resistant leukemia. PMID:7622426

  7. Imipramine exploits histone deacetylase 11 to increase the IL-12/IL-10 ratio in macrophages infected with antimony-resistant Leishmania donovani and clears organ parasites in experimental infection.

    PubMed

    Mukherjee, Sandip; Mukherjee, Budhaditya; Mukhopadhyay, Rupkatha; Naskar, Kshudiram; Sundar, Shyam; Dujardin, Jean-Claude; Roy, Syamal

    2014-10-15

    The efflux of antimony through multidrug resistance protein (MDR)-1 is the key factor in the failure of metalloid treatment in kala-azar patients infected with antimony-resistant Leishmania donovani (Sb(R)LD). Previously we showed that MDR-1 upregulation in Sb(R)LD infection is IL-10-dependent. Imipramine, a drug in use for the treatment of depression and nocturnal enuresis in children, inhibits IL-10 production from Sb(R)LD-infected macrophages (Sb(R)LD-Mϕs) and favors accumulation of surrogates of antimonials. It inhibits IL-10-driven nuclear translocation of c-Fos/c-Jun, critical for enhanced MDR-1 expression. The drug upregulates histone deacetylase 11, which inhibits acetylation of IL-10 promoter, leading to a decrease in IL-10 production from Sb(R)LD-Mϕs. It abrogates Sb(R)LD-mediated p50/c-Rel binding to IL-10 promoter and preferentially recruits p65/RelB to IL-12 p35 and p40 promoters, causing a decrease in IL-10 and overproduction of IL-12 in Sb(R)LD-Mϕs. Histone deacetylase 11 per se does not influence IL-12 promoter activity. Instead, a imipramine-mediated decreased IL-10 level allows optimal IL-12 production in Sb(R)LD-Mϕs. Furthermore, exogenous rIL-12 inhibits intracellular Sb(R)LD replication, which can be mimicked by the presence of Ab to IL-10. This observation indicated that reciprocity exists between IL-10 and IL-12 and that imipramine tips the balance toward an increased IL-12/IL-10 ratio in Sb(R)LD-Mϕs. Oral treatment of infected BALB/c mice with imipramine in combination with sodium stibogluconate cleared organ Sb(R)LD parasites and caused an expansion of the antileishmanial T cell repertoire where sodium stibogluconate alone had no effect. Our study deciphers a detailed molecular mechanism of imipramine-mediated regulation of IL-10/IL-12 reciprocity and its impact on Sb(R)LD clearance from infected hosts.

  8. Radiosynthesis and in vivo evaluation of 1-[18F]fluoroelacridar as a positron emission tomography tracer for P-glycoprotein and breast cancer resistance protein

    PubMed Central

    Dörner, Bernd; Kuntner, Claudia; Bankstahl, Jens P.; Wanek, Thomas; Bankstahl, Marion; Stanek, Johann; Müllauer, Julia; Bauer, Florian; Mairinger, Severin; Löscher, Wolfgang; Miller, Donald W.; Chiba, Peter; Müller, Markus; Erker, Thomas; Langer, Oliver

    2013-01-01

    Aim of this study was to label the potent dual P-glycoprotein (Pgp) and breast cancer resistance protein (BCRP) inhibitor elacridar (1) with 18F to provide a positron emission tomography (PET) radiotracer to visualize Pgp and BCRP. A series of new 1- and 2-halogen- and nitro-substituted derivatives of 1 (4a-e) was synthesized as precursor molecules and reference compounds for radiolabelling and shown to display comparable in vitro potency to 1 in increasing rhodamine 123 accumulation in a cell line overexpressing human Pgp (MDCKII-MDR1). 1-[18F]fluoroelacridar ([18F]4b) was synthesized in a decay-corrected radiochemical yield of 1.7±0.9% by a 1-step no-carrier added nucleophilic aromatic 18F-substitution of 1-nitro precursor 4c. Small-animal PET imaging of [18F]4b was performed in naïve rats, before and after administration of unlabelled 1 (5 mg/kg, n=3), as well as in wild-type and Mdr1a/b(−/−)Bcrp1(−/−) mice (n=3). In PET experiments in rats, administration of unlabelled 1 increased brain activity uptake by a factor of 9.5 (p=0.0002, 2-tailed Student’s t-test), whereas blood activity levels remained unchanged. In Mdr1a/b(−/−)Bcrp1(−/−) mice, the mean brain-to-blood ratio of activity at 60 min after tracer injection was 7.6 times higher as compared to wild-type animals (p=0.0002). HPLC analysis of rat brain tissue extracts collected at 40 min after injection of [18F]4b revealed that 93±7% of total radioactivity in brain was in the form of unchanged [18F]4b. In conclusion, the in vivo behavior of [18F]4b was found to be similar to previously described [11C]1 suggesting transport of [18F]4b by BCRP and/or Pgp at the rodent BBB. However, low radiochemical yields and a significant degree of in vivo defluorination will limit the utility of [18F]4b as a PET tracer. PMID:21419632

  9. Synthesis and preclinical evaluation of the radiolabeled P-glycoprotein inhibitor [11C]MC113

    PubMed Central

    Mairinger, Severin; Wanek, Thomas; Kuntner, Claudia; Doenmez, Yaprak; Strommer, Sabine; Stanek, Johann; Capparelli, Elena; Chiba, Peter; Müller, Markus; Colabufo, Nicola A.; Langer, Oliver

    2013-01-01

    Objectives With the aim to develop a PET tracer to visualize P-glycoprotein (Pgp) expression levels in different organs, the Pgp inhibitor MC113 was labeled with 11C and evaluated using small-animal PET. Methods [11C]MC113 was synthesized by reaction of O-desmethyl MC113 with [11C]methyl triflate. Small-animal PET was performed with [11C]MC113 in FVB wild-type and Mdr1a/b(−/−) mice (n=3 per group) and in a mouse model of high (EMT6Ar1.0) and low (EMT6) Pgp expressing tumor grafts (n=5). In the tumor model, PET scans were performed before and after administration of the reference Pgp inhibitor tariquidar (15 mg/kg). Results Brain uptake of [11C]MC113, expressed as area under the time-activity curve from time 0 to 60 min (AUC0-60), was moderately but not significantly increased in Mdr1a/b(−/−) compared with wild-type mice (mean±SD AUC0-60, Mdr1a/b(−/−): 88±7 min, wild-type: 62±6 min, P=0.100, Mann Whitney test). In the tumor model, AUC0-60 values were not significantly different between EMT6Ar1.0 and EMT6 tumors. Neither in brain nor in tumors was activity concentration significantly changed in response to tariquidar administration. Half-maximum effect concentrations (IC50) for inhibition of Pgp-mediated rhodamine 123 efflux from CCRFvcr1000 cells were 375±60 nM for MC113 versus 8.5±2.5 nM for tariquidar. Conclusion [11C]MC113 showed higher brain uptake in mice than previously described Pgp PET tracers, suggesting that [11C]MC113 was only to a low extent effluxed by Pgp. However, [11C]MC113 was found unsuitable to visualize Pgp expression levels presumably due to insufficiently high Pgp binding affinity of MC113 in relation to Pgp densities in brain and tumors. PMID:22981987

  10. Establishment of a human hepatoma multidrug resistant cell line in vitro

    PubMed Central

    Zhou, Yuan; Ling, Xian-Long; Li, Shi-Wei; Li, Xin-Qiang; Yan, Bin

    2010-01-01

    AIM: To establish a multidrug-resistant hepatoma cell line (SK-Hep-1), and to investigate its biological characteristics. METHODS: A highly invasive SK-Hep-1 cell line of human hepatocellular carcinoma, also known as malignant hepatoma was incubated with a high concentration of cisplatin (CDDP) to establish a CDDP-resistant cell subline (SK-Hep-1/CDDP). The 50% inhibitory dose (IC50) values and the resistance indexes [(IC50 SK-Hep-1/CDDP)/(IC50 SK-Hep-1)] for other chemotherapeutic agents and the growth curve of cells were all evaluated using cell counting kit-8 assays. The distribution of the cell cycles were detected by flow cytometry. Expression of acquired multidrug resistance P-glycoprotein (MDR1, ABCB1) and multidrug resistance-associated protein 1 (MRP1, ABCC1) was compared with that in parent cells by Western blotting and immunofluorescence combined with laser scanning confocal microscopy. RESULTS: The SK-Hep-1/CDDP cells (IC50 = 70.61 ± 1.06 μg/mL) was 13.76 times more resistant to CDDP than the SK-Hep-1 cells (IC50 = 5.13 ± 0.09 μg/mL), and CDDP-resistant cells also demonstrated cross-resistance to many anti-tumor agents such as doxorubicin, 5-fluorouracil and vincristine. Similar morphologies were determined in both SK-Hep-1 and SK-Hep-1/CDDP groups. The cell cycle distribution of the SK-Hep-1/CDDP cell line exhibited a significantly increased percentage of cells in S (42.2% ± 2.65% vs 27.91% ± 2.16%, P < 0.01) and G2/M (20.67% ± 5.69% vs 12.14% ± 3.36%, P < 0.01) phases in comparison with SK-Hep-1 cells, while the percentage of cells in the G0/G1 phase decreased (37.5% ± 5.05% vs 59.83% ± 3.28%, P < 0.01). The levels of MDR1 and MRP1 were overexpressed in the SK-Hep-1/CDDP cells exhibiting the MDR phenotype. CONCLUSION: Multiple drug resistance of multiple drugs in the human hepatoma cell line SK-Hep-1/CDDP was closely related to the overexpression of MDR1 and MRP1. PMID:20458768

  11. Cytotoxicity, toxicity, and anticancer activity of Zingiber officinale Roscoe against cholangiocarcinoma.

    PubMed

    Plengsuriyakarn, Tullayakorn; Viyanant, Vithoon; Eursitthichai, Veerachai; Tesana, Smarn; Chaijaroenkul, Wanna; Itharat, Arunporn; Na-Bangchang, Kesara

    2012-01-01

    Cholangiocarcinoma (CCA) is an uncommon adenocarcinoma which arises from the epithelial cells of the bile ducts. The aim of the study was to investigate the cytotoxicity, toxicity, and anticancer activity of a crude ethanolic extract of ginger (Zingiber officinale Roscoe) against CCA. Cytotoxic activity against a CCA cell line (CL-6) was assessed by calcein-AM and Hoechst 33342 assays and anti-oxidant activity was evaluated using the DPPH assay. Investigation of apoptotic activity was performed by DNA fragmentation assay and induction of genes that may be involved in the resistance of CCA to anticancer drugs (MDR1, MRP1, MRP2, and MRP3) was examined by real-time PCR. To investigate anti-CCA activity in vivo, a total of 80 OV and nitrosamine (OV/ DMN)-induced CCA hamsters were fed with the ginger extract at doses of 1000, 3000, and 5000 mg/kg body weight daily or every alternate day for 30 days. Control groups consisting of 10 hamsters for each group were fed with 5-fluorouracil (positive control) or distilled water (untreated control). Median IC50 (concentration that inhibits cell growth by 50%) values for cytotoxicity and anti-oxidant activities of the crude ethanolic extract of ginger were 10.95, 53.15, and 27.86 μg/ml, respectively. More than ten DNA fragments were visualized and up to 7-9 fold up-regulation of MDR1 and MRP3 genes was observed following exposure to the ethanolic extract of ginger. Acute and subacute toxicity tests indicated absence of any significant toxicity at the maximum dose of 5,000 mg/kg body weight given by intragastric gavage. The survival time and survival rate of the CCA-bearing hamsters were significantly prolonged compared to the control group (median of 54 vs 17 weeks). Results from these in vitro and in vivo studies thus indicate promising anticancer activity of the crude ethanolic extract of ginger against CCA with the absence of any significant toxicity. Moreover, MDR1 and MRP3 may be involved in conferring resistance of CCA to

  12. Non-coplanar polychlorinated biphenyls (PCBs) are direct agonists for the human pregnane-X receptor and constitutive androstane receptor, and activate target gene expression in a tissue-specific manner

    SciTech Connect

    Al-Salman, Fadheela; Plant, Nick

    2012-08-15

    The polychlorinated biphenyl group possesses high environmental persistence, leading to bioaccumulation and a number of adverse effects in mammals. Whilst coplanar PCBs elicit their toxic effects through agonism of the aryl hydrocarbon receptor; however, non-coplanar PCBs are not ligands for AhR, but may be ligands for members of the nuclear receptor family of proteins. To better understand the biological actions of non-coplanar PCBs, we have undertaken a systematic analysis of their ability to activate PXR and CAR-mediated effects. Cells were exposed to a range of non-coplanar PCBs (99, 138, 153, 180 and 194), or the coplanar PCB77: Direct activation of PXR and CAR was measured using a mammalian receptor activation assay in human liver cells, with rifampicin and CITCO used as positive controls ligands for PXR and CAR, respectively; activation of target gene expression was examined using reporter gene plasmids for CYP3A4 and MDR1 transfected into liver, intestine and lung cell lines. Several of the non-coplanar PCBs directly activated PXR and CAR, whilst the coplanar PCB77 did not. Non-coplanar PCBs were also able to activate PXR/CAR target gene expression in a substitution- and tissue-specific manner. Non-coplanar PCBs act as direct activators for the nuclear receptors PXR and CAR, and are able to elicit transcriptional activation of target genes in a substitution- and tissue-dependent manner. Chronic activation of PXR/CAR is linked to adverse effects and must be included in any risk assessment of PCBs. -- Highlights: ► Several Non-coplanar PCBs are able to directly activate both PXR and CAR in vitro. ► PCB153 is the most potent direct activator of PXR and CAR nuclear receptors. ► Non-coplanar PCB activation of CYP3A4/MDR1 reporter genes is structure-dependent. ► Non-coplanar PCB activate CYP3A4/MDR1 reporter genes in a tissue-dependent. ► PCB153 is the most potent activator of PXR/CAR target gene in all tissues.

  13. Staphylococcus aureus and Lipopolysaccharide Modulate Gene Expressions of Drug Transporters in Mouse Mammary Epithelial Cells Correlation to Inflammatory Biomarkers

    PubMed Central

    Yagdiran, Yagmur; Tallkvist, Jonas; Artursson, Karin

    2016-01-01

    Inflammation in the mammary gland (mastitis) is the most common disease in dairy herds worldwide, often caused by the pathogens Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Little is known about the effects of mastitis on drug transporters and the impact on transporter-mediated excretion of drugs into milk. We used murine mammary epithelial HC11 cells, after lactogenic differentiation into a secreting phenotype, and studied gene expressions of ABC- and SLC- transporters after treatment of cells with S. aureus and lipopolysaccharide, an endotoxin secreted by E. coli. The studied transporters were Bcrp, Mdr1, Mrp1, Oatp1a5, Octn1 and Oct1. In addition, Csn2, the gene encoding β-casein, was analyzed. As biomarkers of the inflammatory response, gene expressions of the cytokines Il6 and Tnfα and the chemokine Cxcl2 were determined. Our results show that S. aureus and LPS treatment of cells, at non-cytotoxic concentrations, induced an up-regulation of Mdr1 and of the inflammatory biomarkers, except that Tnfα was not affected by lipopolysaccharide. By simple regression analysis we could demonstrate statistically significant positive correlations between each of the transporters with each of the inflammatory biomarkers in cells treated with S. aureus. The coefficients of determination (R2) were 0.7–0.9 for all but one correlation. After treatment of cells with lipopolysaccharide, statistically significant correlations were only found between Mdr1 and the two parameters Cxcl2 and Il6. The expression of Csn2 was up-regulated in cells treated with S. aureus, indicating that the secretory function of the cells was not impaired. The strong correlation in gene expressions between transporters and inflammatory biomarkers may suggest a co-regulation and that the transporters have a role in the transport of cytokines and chemokines. Our results demonstrate that transporters in mammary cells can be affected by infection, which may have an impact on

  14. Staphylococcus aureus and Lipopolysaccharide Modulate Gene Expressions of Drug Transporters in Mouse Mammary Epithelial Cells Correlation to Inflammatory Biomarkers.

    PubMed

    Yagdiran, Yagmur; Tallkvist, Jonas; Artursson, Karin; Oskarsson, Agneta

    2016-01-01

    Inflammation in the mammary gland (mastitis) is the most common disease in dairy herds worldwide, often caused by the pathogens Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Little is known about the effects of mastitis on drug transporters and the impact on transporter-mediated excretion of drugs into milk. We used murine mammary epithelial HC11 cells, after lactogenic differentiation into a secreting phenotype, and studied gene expressions of ABC- and SLC- transporters after treatment of cells with S. aureus and lipopolysaccharide, an endotoxin secreted by E. coli. The studied transporters were Bcrp, Mdr1, Mrp1, Oatp1a5, Octn1 and Oct1. In addition, Csn2, the gene encoding β-casein, was analyzed. As biomarkers of the inflammatory response, gene expressions of the cytokines Il6 and Tnfα and the chemokine Cxcl2 were determined. Our results show that S. aureus and LPS treatment of cells, at non-cytotoxic concentrations, induced an up-regulation of Mdr1 and of the inflammatory biomarkers, except that Tnfα was not affected by lipopolysaccharide. By simple regression analysis we could demonstrate statistically significant positive correlations between each of the transporters with each of the inflammatory biomarkers in cells treated with S. aureus. The coefficients of determination (R2) were 0.7-0.9 for all but one correlation. After treatment of cells with lipopolysaccharide, statistically significant correlations were only found between Mdr1 and the two parameters Cxcl2 and Il6. The expression of Csn2 was up-regulated in cells treated with S. aureus, indicating that the secretory function of the cells was not impaired. The strong correlation in gene expressions between transporters and inflammatory biomarkers may suggest a co-regulation and that the transporters have a role in the transport of cytokines and chemokines. Our results demonstrate that transporters in mammary cells can be affected by infection, which may have an impact on transport

  15. Novel dihydro-beta-agarofuran sesquiterpenes as potent modulators of human P-glycoprotein dependent multidrug resistance.

    PubMed

    Torres-Romero, David; Muñoz-Martínez, Francisco; Jiménez, Ignacio A; Castanys, Santiago; Gamarro, Francisco; Bazzocchi, Isabel L

    2009-12-21

    P-Glycoprotein (Pgp) overexpression is one factor contributing to multidrug resistance (MDR) in cancer cells and represents one drawback in the treatment of cancer. In an attempt to find more specific and less toxic anticancer MDR-reversal agents, we report herein the isolation, structure elucidation and biological activity of nine new (, and ) and seven known (, and ) dihydro-beta-agarofuran sesquiterpenes from the leaves of Celastrus vulcanicola. Their stereostructures were elucidated on the basis of spectroscopic analysis, including 1D and 2D NMR techniques, CD studies and biogenetic means. All the compounds were assayed on human MDR1-transfected NIH-3T3 cells, in order to determine their ability to reverse the MDR phenotype due to Pgp overexpression. Six compounds from these series (, , , , and ) showed an effectiveness that was similar to (or higher than) the classical Pgp reversal agent verapamil for the reversal of resistance to daunomycin and vinblastine. The structure-activity relationships are discussed. PMID:20024113

  16. A Locked Nucleic Acid Probe Based on Selective Salt-Induced Effect Detects Single Nucleotide Polymorphisms

    PubMed Central

    Zhang, Jing; Wu, Huizhe; Chen, Qiuchen; Zhao, Pengfei; Zhao, Haishan; Yao, Weifan; Wei, Minjie

    2015-01-01

    Detection of single based genetic mutation by using oligonucleotide probes is one of the common methods of detecting single nucleotide polymorphisms at known loci. In this paper, we demonstrated a hybridization system which included a buffer solution that produced selective salt-induced effect and a locked nucleic acid modified 12 nt oligonucleotide probe. The hybridization system is suitable for hybridization under room temperature. By using magnetic nanoparticles as carriers for PCR products, the SNPs (MDR1 C3435T/A) from 45 volunteers were analyzed, and the results were consistent with the results from pyrophosphoric acid sequencing. The method presented in this paper differs from the traditional method of using molecular beacons to detect SNPs in that it is suitable for research institutions lacking real-time quantitative PCR detecting systems, to detect PCR products at room temperature. PMID:26347880

  17. Comparative Study on the MDR Reversal Effects of Selected Chalcones

    PubMed Central

    Ivanova, A. B.; Batovska, D. I.; Todorova, I. T.; Stamboliyska, B. A.; Serly, J.; Molnar, J.

    2011-01-01

    Based on the structure of three previously established lead compounds, fifteen selected chalcones were synthesized and evaluated for their multidrug resistance (MDR) reversal activity on mouse lymphoma cells. The most active chalcones were stronger revertants than the positive control, verapamil. In the model of combination chemotherapy, the interactions between the anticancer drug doxorubicin and two of the most effective compounds were measured in vitro, on human MDR1 gene transfected mouse lymphoma cells, showing that the type of interaction for one of these compounds was indifferent while that for the other one was additive. Furthermore, two chalcones inhibited 50% of cell proliferation in concentration of around 0.4 μg/mL and were from 2- to 100-fold more active than the most chalcones. The structure-activity relationships were obtained and discussed in view of their usefulness for the design of chalcone-like P-gp modulators and drugs able to treat resistant cancers. PMID:27516904

  18. Comparative Study on the MDR Reversal Effects of Selected Chalcones.

    PubMed

    Ivanova, A B; Batovska, D I; Todorova, I T; Stamboliyska, B A; Serly, J; Molnar, J

    2011-01-01

    Based on the structure of three previously established lead compounds, fifteen selected chalcones were synthesized and evaluated for their multidrug resistance (MDR) reversal activity on mouse lymphoma cells. The most active chalcones were stronger revertants than the positive control, verapamil. In the model of combination chemotherapy, the interactions between the anticancer drug doxorubicin and two of the most effective compounds were measured in vitro, on human MDR1 gene transfected mouse lymphoma cells, showing that the type of interaction for one of these compounds was indifferent while that for the other one was additive. Furthermore, two chalcones inhibited 50% of cell proliferation in concentration of around 0.4 μg/mL and were from 2- to 100-fold more active than the most chalcones. The structure-activity relationships were obtained and discussed in view of their usefulness for the design of chalcone-like P-gp modulators and drugs able to treat resistant cancers. PMID:27516904

  19. Hesperetin Liposomes for Cancer Therapy.

    PubMed

    Wolfram, Joy; Scott, Bronwyn; Boom, Kathryn; Shen, Jianliang; Borsoi, Carlotta; Suri, Krishna; Grande, Rossella; Fresta, Massimo; Celia, Christian; Zhao, Yuliang; Shen, Haifa; Ferrari, Mauro

    2016-01-01

    Hesperetin is a compound from citrus fruit that has previously been found to exert anticancer activity through a variety of mechanisms. However, the application of hesperetin to cancer therapy has been hampered by its hydrophobicity, necessitating the use of toxic solubilizing agents. Here, we have developed the first liposome-based delivery system for hesperetin. Liposomes were fabricated using the thin-layer evaporation technique and physical and pharmacological parameters were measured. The liposomes remained stable for prolonged periods of time in serum and under storage conditions, and displayed anticancer efficacy in both H441 lung cancer cells and MDA-MB-231 breast cancer cells. Furthermore, the anticancer activity was not impaired in cells expressing the multidrug resistance protein 1 (MDR-1). In conclusion, the encapsulation of hesperetin in liposomes does not interfere with therapeutic efficacy and provides a biocompatible alternative to toxic solubilizing agents, thereby enabling future clinical use of this compound for cancer therapy.

  20. Potent galloyl-based selective modulators targeting multidrug resistance associated protein 1 and P-glycoprotein.

    PubMed

    Pellicani, Raffaella Zoe; Stefanachi, Angela; Niso, Mauro; Carotti, Angelo; Leonetti, Francesco; Nicolotti, Orazio; Perrone, Roberto; Berardi, Francesco; Cellamare, Saverio; Colabufo, Nicola Antonio

    2012-01-12

    The multifactorial nature of chemotherapy failure in controlling cancer is often associated with the occurrence of multidrug resistance (MDR), a phenomenon likely related to the increased expression of members of the ATP binding cassette (ABC) transporter superfamily. In this respect, the most extensively characterized MDR transporters include ABCB1 (also known as MDR1 or P-glycoprotein) and ABCC1 (also known as MRP1) whose inhibition remains a priority to circumvent drug resistance. Herein, we report how the simple galloyl benzamide scaffold can be easily and properly decorated for the preparation of either MRP1 or P-gp highly selective inhibitors. In particular, some gallamides and pyrogallol-1-monomethyl ethers showed remarkable affinity and selectivity toward MRP1. On the other hand, trimethyl ether galloyl anilides, with few exceptions, exhibited moderate to very high and selective P-gp inhibition.

  1. Novel dihydro-beta-agarofuran sesquiterpenes as potent modulators of human P-glycoprotein dependent multidrug resistance.

    PubMed

    Torres-Romero, David; Muñoz-Martínez, Francisco; Jiménez, Ignacio A; Castanys, Santiago; Gamarro, Francisco; Bazzocchi, Isabel L

    2009-12-21

    P-Glycoprotein (Pgp) overexpression is one factor contributing to multidrug resistance (MDR) in cancer cells and represents one drawback in the treatment of cancer. In an attempt to find more specific and less toxic anticancer MDR-reversal agents, we report herein the isolation, structure elucidation and biological activity of nine new (, and ) and seven known (, and ) dihydro-beta-agarofuran sesquiterpenes from the leaves of Celastrus vulcanicola. Their stereostructures were elucidated on the basis of spectroscopic analysis, including 1D and 2D NMR techniques, CD studies and biogenetic means. All the compounds were assayed on human MDR1-transfected NIH-3T3 cells, in order to determine their ability to reverse the MDR phenotype due to Pgp overexpression. Six compounds from these series (, , , , and ) showed an effectiveness that was similar to (or higher than) the classical Pgp reversal agent verapamil for the reversal of resistance to daunomycin and vinblastine. The structure-activity relationships are discussed.

  2. Modulation of Expression and Activity of ABC Transporters by the Phytoestrogen Genistein. Impact on Drug Disposition.

    PubMed

    Rigalli, Juan Pablo; Ciriaci, Nadia; Mottino, Aldo Domingo; Catania, Viviana Alicia; Ruiz, María Laura

    2016-01-01

    ATP binding cassette (ABC) transporters are involved in drug absorption, distribution and elimination. They also mediate multidrug resistance in cancer cells. Isoflavones, such as genistein (GNT), belong to a class of naturally-occurring compounds found at high concentrations in commonly consumed soya based-foods and dietary supplements. GNT and its metabolites interact with ABC transporters as substrates, inhibitors and/or modulators of their expression. This review compiles information about regulation of ABC transporters by GNT with special emphasis on the three major groups of ABC transporters involved in excretion of endo- and xenobiotics as follows: Pglycoprotein (MDR1, ABCB1), a group of multidrug resistance associated proteins (MRPs, ABCC subfamily) and ABCG2 (BCRP), an ABC half-transporter. The impact of these regulations on potential GNT-drug interactions is further considered. PMID:27048380

  3. Problems of Glioblastoma Multiforme Drug Resistance.

    PubMed

    Stavrovskaya, A A; Shushanov, S S; Rybalkina, E Yu

    2016-02-01

    Glioblastoma multiforme (GBL) is the most common and aggressive brain neoplasm. A standard therapeutic approach for GBL involves combination therapy consisting of surgery, radiotherapy, and chemotherapy. The latter is based on temozolomide (TMZ). However, even by applying such a radical treatment strategy, the mean patient survival time is only 14.6 months. Here we review the molecular mechanisms underlying the resistance of GBL cells to TMZ including genetic and epigenetic mechanisms. Present data regarding a role for genes and proteins MGMT, IDH1/2, YB-1, MELK, MVP/LRP, MDR1 (ABCB1), and genes encoding other ABC transporters as well as Akt3 kinase in developing resistance of GBL to TMZ are discussed. Some epigenetic regulators of resistance to TMZ such as microRNA and EZH2 are reviewed. PMID:27260389

  4. Celecoxib, a cyclooxygenase-2 inhibitor, potentiates the chemotherapic effect of vinorelbine in the medullary thyroid cancer TT cell line.

    PubMed

    Vivaldi, A; Ciampi, R; Tacito, A; Molinaro, E; Agate, L; Bottici, V; Pinchera, A; Collecchi, P; Elisei, R

    2012-05-15

    We analyzed the in vitro effects of celecoxib, a COX-2 inhibitor, and determined if celecoxib can sensitize a human MTC-derived cell line (TT) to chemotherapeutics. We found that celecoxib induced apoptosis in TT cells and decreased drug efflux by reducing the expression of MDR-1 mRNA, which codes for the drug efflux pump P-gp. We also observed that TT cells were 10-fold more resistant to doxorubicin than to vinorelbine, mimicking what can be observed in clinical practice. In addition, we found that the combination of celecoxib and vinorelbine, but not doxorubicin, induced a significant reduction in cell viability and a significant increase in apoptosis. In conclusion, we showed that celecoxib was able to enhance the chemotherapeutic effect of vinorelbine. A clinical trial exploring the in vivo activities of celecoxib in MTC patients who cannot benefit from available treatments would be desirable, taking into account the possible risks of cardiovascular effects of this drug. PMID:22305971

  5. Impact of passive permeability and gut efflux transport on the oral bioavailability of novel series of piperidine-based renin inhibitors in rodents.

    PubMed

    Lévesque, Jean-François; Bleasby, Kelly; Chefson, Amandine; Chen, Austin; Dubé, Daniel; Ducharme, Yves; Fournier, Pierre-André; Gagné, Sébastien; Gallant, Michel; Grimm, Erich; Hafey, Michael; Han, Yongxin; Houle, Robert; Lacombe, Patrick; Laliberté, Sébastien; MacDonald, Dwight; Mackay, Bruce; Papp, Robert; Tschirret-Guth, Richard

    2011-09-15

    An oral bioavailability issue encountered during the course of lead optimization in the renin program is described herein. The low F(po) of pyridone analogs was shown to be caused by a combination of poor passive permeability and gut efflux transport. Substitution of pyridone ring for a more lipophilic moiety (logD>1.7) had minimal effect on rMdr1a transport but led to increased passive permeability (P(app)>10 × 10(-6) cm/s), which contributed to overwhelm gut transporters and increase rat F(po). LogD and in vitro passive permeability determination were found to be key in guiding SAR and improve oral exposure of renin inhibitors.

  6. Use of a cloned multidrug resistance gene for coamplification and overproduction of major excreted protein, a transformation-regulated secreted acid protease

    SciTech Connect

    Kane, S.E.; Troen, B.R.; Gal, S.; Ueda, K.; Pastan, I.; Gottesman, M.M.

    1988-08-01

    Malignantly transformed mouse fibroblasts synthesize and secrete large amounts of major excreted protein (MEP), a 39,000-dalton precursor to an acid protease (cathepsin L). To evaluate the possible role of this protease in the transformed phenotype, the authors transfected cloned genes for mouse or human MEP into mouse MIH 3T3 cells with an expression vector for the dominant, selectable human multidrug resistance (MDR1) gene. The cotransfected MEP sequences were efficiently coamplified and transcribed during stepwise selection for multidrug resistance in colchicine. The transfected NIH 3T3 cell lines containing amplified MEP sequences synthesized as much MEP as did Kirsten sarcoma virus-transformed NIH 3T3 cells. The MEP synthesized by cells transfected with the cloned mouse and human MEP genes were also secreted. Elevated synthesis and secretion of MEP by NIH 3T3 cells did not change the nontransformed phenotype of these cells.

  7. [Exposition to drugs of abuse in pregnancy and breastfed babies growth in CONIN Valparaíso, Chile].

    PubMed

    Piñuñuri, Raúl; Mardones, Constanza; Valenzuela, Carina; Estay, Pamela; Llanos, Miguel

    2015-05-01

    Introducción: Las consecuencias de la exposición fetal a drogas de abuso en niños han sido estudiadas extensamente. El presente estudio pretende describir la realidad chilena en esta materia, caracterizando el crecimiento de niños expuestos a drogas durante la vida fetal. Objetivo: Comparar la antropometría entre neonatos expuestos a drogas por consumo materno durante el embarazo y controles no expuestos, de los 0 a 6 meses de vida. Materiales y métodos: Se obtuvieron los datos antropométricos desde el nacimiento y hasta los 6 meses de vida de 74 individuos sanos atendidos en Centros de Salud de la comuna de Valparaíso, y de 61 individuos con antecedentes de consumo de drogas de la madre durante el embarazo, atendidos en la Corporación para la Nutrición Infantil (CONIN). Posteriormente se compararon las diferencias entre ambos grupos mediante (T-Student por grupos). Resultados: Según la edad gestacional hay diferencias en la proporción de individuos de pretérmino entre grupos de estudio, observándose una prevalencia de menos del 11% en el grupo no expuesto y superior al 25% en el grupo expuesto. En base a las curvas de los Dres. Pittaluga y Alarcón para crecimiento intrauterino, el grupo expuesto tuvo mayor cantidad de sujetos pequeños para la edad gestacional en ambos sexos, con 37% en CONIN y menos del 6% en el grupo no expuesto. El análisis estadístico muestra que existen diferencias significativas (p.

  8. Effect of HEPES buffer on the uptake and transport of P-glycoprotein substrates and large neutral amino acids

    PubMed Central

    Luo, Shuanghui; Pal, Dhananjay; Shah, Sujay J.; Kwatra, Deep; Paturi, Kalyani D.; Mitra, Ashim. K.

    2010-01-01

    HEPES has been widely employed as an organic buffer agent in cell culture medium as well as uptake and transport experiments in vitro. However, concentrations of HEPES used in such studies vary from one laboratory to another. In this study, we investigated the effect of HEPES on the uptake and bidirectional transport of P-gp substrates employing both Caco-2 and MDCK-MDR1 cells. ATP-dependent uptake of glutamic acid was also examined. ATP production was further quantified applying ATP Determination Kit. An addition of HEPES to the cellular washing and incubation media significantly altered the uptake and transport of P-gp substrates in both Caco-2 and MDCK-MDR1 cells. Uptake of P-gp substrates substantially diminished as the HEPES concentration was raised to 25 mM. Bidirectional (A-B and B-A) transport studies revealed that permeability ratio of PappB-A to PappA-B in the presence of 25 mM HEPES was significantly higher than control. The uptake of phenylalanine is an ATP-independent process, whereas the accumulation of glutamic acid is ATP-dependent. While phenylalanine uptake remained unchanged glutamic acid uptake was elevated with the addition of HEPES. Verapamil is an inhibitor of P-gp mediated uptake, elevation of cyclosporine uptake in the presence of 5 μM verapamil was compromised by the presence of 25 mM HEPES. The results of ATP assay indicated that HEPES stimulated the production of ATP. This study suggests that the addition of HEPES in the medium modulated the energy dependent efflux and uptake processes. The effect of HEPES on P-gp mediated drug efflux and transport may provide some mechanistic insight into possible reasons for inconsistencies in the results reported from various laboratories. PMID:20163160

  9. The effect of polymorphisms in candidate genes on the long-term risk of lipodystrophy and dyslipidemia in HIV-infected white patients starting antiretroviral therapy.

    PubMed

    Marzocchetti, Angela; Schwarz, Jessica; Di Giambenedetto, Simona; Colafigli, Manuela; Bracciale, Laura; Fabbiani, Massimilliano; Fantoni, Massimo; Trecarichi, Enrico; Cauda, Roberto; De Luca, Andrea

    2011-12-01

    We investigated whether polymorphisms in human candidate genes could be associated with a different risk of developing lipodystrophy and dyslipidemia in HIV-infected patients starting combination antiretroviral therapy (cART). Genomic DNA samples from white HIV-1-infected patients were analyzed for seven polymorphisms located in the MDR1, TNF-α, APM1, APOE, and LPL genes. Lipid data were retrospectively collected beginning with the initiation of cART. Lipodystrophy was assessed cross-sectionally and then prospectively. The association with lipodystrophy and National Cholesterol Evaluation Program Adult Treatment Panel III-defined lipid thresholds was analyzed using survival analysis and logistic regression. One-hundred and seventy-four patients were genotyped. In 151 patients assessed for lipodystrophy, MDR1 3435 T homozygosis was associated with a higher hazard (adjusted hazard ratio, aHR, versus CT 0.25; p=0.02) and tumor necrosis factor (TNF)-α 308 G homozygosis with a lower hazard (vs. AA aHR 2.14; p=0.04) of developing trunk fat accumulation after adjusting for gender and initial cART type. The TNF 238 GG genotype was associated with a higher risk of developing low HDL-cholesterol levels (adjusted odd ratio, aOR, 5.91; p=0.01) while patients carrying the LPL S477X mutation were at lower risk of reaching high non-HDL-cholesterol levels (aOR 0.39; p=0.05). The APOEe3/3 genotype patients were at lower risk (aOR 0.26, p=0.015), whereas the adiponectin 276 GT carriers were at higher risk of developing hypertriglyceremia (vs. GG aOR 3.10; p=0.04). Knowledge of the effect of genetic determinants on dyslipidemia and lipodystrophy may prompt the investigation of potential pathogenetic mechanisms and might eventually be used for guiding individualized treatment decisions.

  10. Rosuvastatin blocks hERG current and prolongs cardiac repolarization.

    PubMed

    Plante, Isabelle; Vigneault, Patrick; Drolet, Benoît; Turgeon, Jacques

    2012-02-01

    Blocking of the potassium current I(Kr) [human ether-a-go-go related gene (hERG)] is generally associated with an increased risk of long QT syndrome (LQTS). The 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitor, rosuvastatin, is a methanesulfonamide derivative, which shows structural similarities with several I(Kr) blockers. Hence, we assessed the effects of rosuvastatin on cardiac repolarization by using in vitro, ex vivo, and in vivo models. Patch clamp experiments on hERG-transfected human embryonic kidney (HEK) 293 cells established the potency of rosuvastatin to block hERG [half maximal inhibitory concentration (IC(50) ) = 195 nM]. We showed in isolated guinea pig hearts that 195 nM rosuvastatin prolonged (basic cycle length of 250 ms; p < 0.05) the monophasic action potential duration at 90% repolarization (MAPD(90) ) by 11 ± 1 ms. Finally, rosuvastatin (10 mg/kg, intraperitoneal) prolonged corrected QT interval (QTc) in conscious and unrestrained guinea pigs from 201 ± 1 to 210 ± 2 ms (p < 0.05). Thus, rosuvastatin blocks I(Kr) and prolongs cardiac repolarization. In additional experiments, we also show that hERG blockade in HEK 293 cells was modulated by coexpression of efflux [breast cancer resistance protein (BCRP), multidrug resistance gene (MDR1)] and influx [organic anion transporting polypeptide (OATP) 2B1] transporters involved in the disposition and cardiac distribution of the drug. Genetic polymorphisms observed for BCRP, MDR1, and OATP2B1, and IC(50) determined for hERG blocking lead us to propose that some patients may be at risk of rosuvastatin-induced LQTS.

  11. P-glycoprotein expression in normal and reactive bone marrows.

    PubMed Central

    Hegewisch-Becker, S.; Fliegner, M.; Tsuruo, T.; Zander, A.; Zeller, W.; Hossfeld, D. K.

    1993-01-01

    The expression of mdr1 gene product P-glycoprotein (P-gp) was investigated in 53 normal and reactive bone marrows by means of immunocytochemistry, using the monoclonal antibody (mAb) C219 and the alkaline phosphatase anti-alkaline phosphatase method. In a limited number of patients, data were confirmed by using the mAb MRK16 or a polymerase chain reaction assay for mdr1 gene expression. There was no history of prior chemotherapy or any malignancy in this group. Bone marrow aspirates were obtained as part of a routine diagnostic programme in bone marrow donors or in patients presenting with a variety of diagnoses such as unexplained gammopathy, fever, anaemia, other changes in peripheral blood smear, rheumatoid arthritis, vasculitis, or urticaria pigmentosa. Morphologically the bone marrow was normal in 23 patients, a megaloblastic erythropoiesis was seen in two patients and unspecific changes were seen in 28 patients. Twenty-seven of 53 samples were found to be positive for P-gp expression with the percentage of positive cells ranging from 2%-80% (mean = 24%). With a cutoff point of 10%, five of 23 normal (22%) and 13 of 28 reactive bone marrows (46%) were considered positive for P-gp expression. There was no obvious correlation between diagnosis or age and P-gp expression. Additional staining for the early surface marker CD-34 was performed in 12 samples, with none of them revealing more than 1% positivity. Since P-gp expression has so far been described only in CD-34 positive bone marrow cells, data suggest that P-gp expression may be reinduced in CD-34 negative cells under conditions which remain to be determined. Images Figure 1 Figure 2 PMID:8094974

  12. Reversal of efflux mediated antifungal resistance underlies synergistic activity of two monoterpenes with fluconazole.

    PubMed

    Ahmad, Aijaz; Khan, Amber; Manzoor, Nikhat

    2013-01-23

    Thymol (THY) and carvacrol (CARV), the principal chemical components of thyme oil have long been known for their wide use in medicine due to antimicrobial and disinfectant properties. This study, however, draws attention to a possible synergistic antifungal effect of these monoterpenes with azole antimycotic-fluconazole. Resistance to azoles in Candida albicans involves over-expression of efflux-pump genes MDR1, CDR1, CDR2 or mutations and over-expression of target gene ERG11. The inhibition of drug efflux pumps is considered a feasible strategy to overcome clinical antifungal resistance. To put forward this approach, we investigated the combination effects of these monoterpenes and FLC against 38 clinically obtained FLC-sensitive, and eleven FLC-resistant Candida isolates. Synergism was observed with combinations of THY-FLC and CARV-FLC evaluated by checkerboard microdilution method and nature of the interactions was calculated by FICI. In addition, antifungal activity was assessed using agar-diffusion and time-kill curves. The drug efflux activity was determined using two dyes, Rhodamine6G (R6G) and fluorescent Hoechst 33342. No significant differences were observed in dye uptakes between FLC-susceptible and resistant isolates, incubated in glucose free buffer. However, a significantly higher efflux was recorded in FLC-resistant isolates when glucose was added. Both monoterpenes inhibited efflux by 70-90%, showing their high potency to block drug transporter pumps. Significant differences, in the expression levels of CDR1 and MDR1, induced by monoterpenes revealed reversal of FLC-resistance. The selectively fungicidal characteristics and ability to restore FLC susceptibility in resistant isolates signify a promising candidature of THY and CARV as antifungal agents in combinational treatments for candidiasis. PMID:23111348

  13. Transporter gene expression in lactating and nonlactating human mammary epithelial cells using real-time reverse transcription-polymerase chain reaction.

    PubMed

    Alcorn, J; Lu, X; Moscow, J A; McNamara, P J

    2002-11-01

    Transporter-mediated processes in the lactating mammary gland may explain the significant accumulation of certain drugs in breast milk. The purpose of this study was to identify potential candidate drug transport proteins involved in drug accumulation in milk. Quantitative reverse transcription-polymerase chain reaction methods were developed to determine the relative RNA levels of 30 different drug transporter genes. Transporter gene RNA levels in lactating mammary epithelial cells (MEC) purified from pooled fresh breast milk samples were compared with levels in nonlactating MEC, liver, and kidney tissue. Transcripts were detected in lactating MEC for OCT1, OCT3, OCTN1, OCTN2, OATP-A, OATP-B, OATP-D, OATP-E, MRP1, MRP2, MRP5, MDR1, CNT1, CNT3, ENT1, ENT3, NCBT1, PEPT1, and PEPT2. No transcripts were detected for OCT2, OAT1, OAT2, OAT3, OAT4, OATP-C, MRP3, MRP4, CNT2, ENT2, and NCBT2. Lactating MEC demonstrated more than 4-fold higher RNA levels of OCT1, OCTN1, PEPT2, CNT1, CNT3, and ENT3, and more than 4-fold lower RNA levels of MDR1 and OCTN2 relative to nonlactating MEC. Lactating MEC showed significantly higher RNA levels of CNT3 relative to liver and kidney, increased PEPT2 RNA levels relative to liver, and increased OATP-A RNA levels relative to kidney. These data imply CNT3 may play a specialized role in nucleoside accumulation in milk and may identify an important role for PEPT2 and OATP-A transporters at the lactating mammary epithelium. Furthermore, transporters expressed in lactating MEC identify a potential role for these transporters in drug disposition at the mammary gland.

  14. P-glycoprotein activity and biological response

    SciTech Connect

    Vaalburg, W. . E-mail: w.vaalburg@pet.umcg.nl; Hendrikse, N.H.; Elsinga, P.H.; Bart, J.; Waarde, A. van

    2005-09-01

    P-glycoprotein (P-gp) is a transmembrane drug efflux pump encoded by the MDR-1 gene in humans. Most likely P-gp protects organs against endogenous and exogenous toxins by extruding toxic compounds such as chemotherapeutics and other drugs. Many drugs are substrates for P-gp. Since P-gp is also expressed in the blood-brain barrier, P-gp substrates reach lower concentrations in the brain than in P-gp-negative tissues. Failure of response to chemotherapy of malignancies can be due to intrinsic or acquired drug resistance. Many tumors are multidrug resistant (MDR); resistant to several structurally unrelated chemotherapeutic agents. Several mechanisms are involved in MDR of which P-gp is studied most extensively. P-gp extrudes drugs out of tumor cells resulting in decreased intracellular drug concentrations, leading to the MDR phenotype. Furthermore, the MDR-1 gene exhibits several single nucleotide polymorphisms, some of which result in different transport capabilities. P-gp functionality and the effect of P-gp modulation on the pharmacokinetics of novel and established drugs can be studied in vivo by positron emission tomography (PET) using carbon-11 and fluorine-18-labeled P-gp substrates and modulators. PET may demonstrate the consequences of genetic differences on tissue pharmacokinetics. Inhibitors such as calcium-channel blockers (verapamil), cyclosporin A, ONT-093, and XR9576 can modulate the P-gp functionality. With PET the effect of P-gp modulation on the bioavailability of drugs can be investigated in humans in vivo. PET also allows the measurement of the efficacy of newly developed P-gp modulators.

  15. Interaction of drugs of abuse and maintenance treatments with human P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2).

    PubMed

    Tournier, Nicolas; Chevillard, Lucie; Megarbane, Bruno; Pirnay, Stéphane; Scherrmann, Jean-Michel; Declèves, Xavier

    2010-08-01

    Drug interaction with P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) may influence its tissue disposition including blood-brain barrier transport and result in potent drug-drug interactions. The limited data obtained using in-vitro models indicate that methadone, buprenorphine, and cannabinoids may interact with human P-gp; but almost nothing is known about drugs of abuse and BCRP. We used in vitro P-gp and BCRP inhibition flow cytometric assays with hMDR1- and hBCRP-transfected HEK293 cells to test 14 compounds or metabolites frequently involved in addiction, including buprenorphine, norbuprenorphine, methadone, ibogaine, cocaine, cocaethylene, amphetamine, N-methyl-3,4-methylenedioxyamphetamine, 3,4-methylenedioxyamphetamine, nicotine, ketamine, Delta9-tetrahydrocannabinol (THC), naloxone, and morphine. Drugs that in vitro inhibited P-gp or BCRP were tested in hMDR1- and hBCRP-MDCKII bidirectional transport studies. Human P-gp was significantly inhibited in a concentration-dependent manner by norbuprenorphine>buprenorphine>methadone>ibogaine and THC. Similarly, BCRP was inhibited by buprenorphine>norbuprenorphine>ibogaine and THC. None of the other tested compounds inhibited either transporter, even at high concentration (100 microm). Norbuprenorphine (transport efflux ratio approoximately 11) and methadone (transport efflux ratio approoximately 1.9) transport was P-gp-mediated; however, with no significant stereo-selectivity regarding methadone enantiomers. BCRP did not transport any of the tested compounds. However, the clinical significance of the interaction of norbuprenorphine with P-gp remains to be evaluated. PMID:19887017

  16. In vitro and in vivo evaluation of the effects of piperine on P-gp function and expression

    SciTech Connect

    Han Yi; Chin Tan, Theresa May; Lim, Lee-Yong

    2008-08-01

    Piperine, a major component of black pepper, is used as spice and nutrient enhancer. The purpose of the present study was to evaluate the effects of acute and prolonged piperine exposure on cellular P-gp expression and function in vitro and in vivo. Piperine at concentrations ranging from 10 to 100 {mu}M, determined by MTT assay to be non-cytotoxic, was observed to inhibit P-gp mediated efflux transport of [{sup 3}H]-digoxin across L-MDR1 and Caco-2 cell monolayers. The acute inhibitory effect was dependent on piperine concentration, with abolishment of [{sup 3}H]-digoxin polarized transport attained at 50 {mu}M of piperine. In contrast, prolonged (48 and 72 h) co-incubation of Caco-2 cell monolayers with piperine (50 and 100 {mu}M) increased P-gp activity through an up-regulation of cellular P-gp protein and MDR1 mRNA levels. The up-regulated protein was functionally active, as demonstrated by a higher degree of [{sup 3}H]-digoxin efflux across the cell monolayers, but the induction was readily reversed by the removal of the spice from the culture medium. Peroral administration of piperine at the dose of 112 {mu}g/kg body weight/day to male Wistar rats for 14 consecutive days also led to increased intestinal P-gp levels. However, there was a concomitant reduction in the rodent liver P-gp although the kidney P-gp level was unaffected. Our data suggest that caution should be exercised when piperine is to be co-administered with drugs that are P-gp substrates, particularly for patients whose diet relies heavily on pepper.

  17. Changes in mRNA expression of ABC and SLC transporters in liver and intestines of the adjuvant-induced arthritis rat.

    PubMed

    Uno, Satoshi; Uraki, Misato; Ito, Ayami; Shinozaki, Yuki; Yamada, Ayano; Kawase, Atsushi; Iwaki, Masahiro

    2009-01-01

    In this study, a real-time reverse transcription-polymerase chain reaction was used to determine the effects of adjuvant-induced arthritis (AA) on the amounts of mRNA of 12 types of rat ATP-binding cassette (ABC) and solute carrier (SLC) transporters in the liver and small intestine, 7 (D7) and 21 days (D21) after the injection of adjuvant. There were no significant differences in mRNA levels of ABC and SLC transporters between the livers of AA and control rats on D7, except in the case of Mdr1a. However, levels of Mdr1a, Mrp2 and Oatp SLC transporters were significantly lower in AA than in the control livers on D21. In contrast, the mRNA levels of several ABC and SLC transporters, especially Mrp2, Bcrp, LAT2 and Oatp1a5, were significantly lower in the small intestines of AA rats compared with the controls on D7, though there were no significant differences by D21. The time-dependent alterations in mRNA levels of the pregnane X receptor, but not the constitutive androstane receptor, in the liver and intestine were similar to the changes in mRNA levels of most transporters examined. The present study showed that AA was associated with reduced mRNA expression of several ABC and SLC transporters in the liver and small intestine, but that the time courses of the effects of AA on mRNA expression differed between the liver and small intestine. These results raise the possibility of a functional change of the transporters of liver and intestine in AA rats.

  18. Candida parapsilosis Resistance to Fluconazole: Molecular Mechanisms and In Vivo Impact in Infected Galleria mellonella Larvae

    PubMed Central

    Souza, Ana Carolina R.; Fuchs, Beth Burgwyn; Pinhati, Henrique M. S.; Siqueira, Ricardo A.; Hagen, Ferry; Meis, Jacques F.

    2015-01-01

    Candida parapsilosis is the main non-albicans Candida species isolated from patients in Latin America. Mutations in the ERG11 gene and overexpression of membrane transporter proteins have been linked to fluconazole resistance. The aim of this study was to evaluate the molecular mechanisms in fluconazole-resistant strains of C. parapsilosis isolated from critically ill patients. The identities of the nine collected C. parapsilosis isolates at the species level were confirmed through molecular identification with a TaqMan qPCR assay. The clonal origin of the strains was checked by microsatellite typing. The Galleria mellonella infection model was used to confirm in vitro resistance. We assessed the presence of ERG11 mutations, as well as the expression of ERG11 and two additional genes that contribute to antifungal resistance (CDR1 and MDR1), by using real-time quantitative PCR. All of the C. parapsilosis (sensu stricto) isolates tested exhibited fluconazole MICs between 8 and 16 μg/ml. The in vitro data were confirmed by the failure of fluconazole in the treatment of G. mellonella infected with fluconazole-resistant strains of C. parapsilosis. Sequencing of the ERG11 gene revealed a common mutation leading to a Y132F amino acid substitution in all of the isolates, a finding consistent with their clonal origin. After fluconazole exposure, overexpression was noted for ERG11, CDR1, and MDR1 in 9/9, 9/9, and 2/9 strains, respectively. We demonstrated that a combination of molecular mechanisms, including the presence of point mutations in the ERG11 gene, overexpression of ERG11, and genes encoding efflux pumps, are involved in fluconazole resistance in C. parapsilosis. PMID:26259795

  19. MRP-1 expression levels determine strain-specific susceptibility to sodium arsenic-induced renal injury between C57BL/6 and BALB/c mice

    SciTech Connect

    Kimura, Akihiko; Ishida, Yuko; Wada, Takashi; Yokoyama, Hitoshi; Mukaida, Naofumi; Kondo, Toshikazu . E-mail: kondot@wakayama-med.ac.jp

    2005-02-15

    To clarify the pathophysiological mechanism underlying acute renal injury caused by acute exposure to arsenic, we subcutaneously injected both BALB/c and C57BL/6 mice with sodium arsenite (NaAs; 13.5 mg/kg). BALB/c mice exhibited exaggerated elevation of serum blood urea nitrogen (BUN) and creatinine (CRE) levels, compared with C57BL/6 mice. Moreover, half of BALB/c mice died by 24 h, whereas all C57BL/6 mice survived. Histopathological examination on kidney revealed severe hemorrhages, acute tubular necrosis, neutrophil infiltration, cast formation, and disappearance of PAS-positive brush borders in BALB/c mice, later than 10 h. These pathological changes were remarkably attenuated in C57BL/6 mice, accompanied with lower intrarenal arsenic concentrations, compared with BALB/c mice. Among heavy metal inducible proteins including multidrug resistance-associated protein (MRP)-1, multidrug resistance gene (MDR)-1, metallothionein (MT)-1, and arsenite inducible, cysteine- and histidine-rich RNA-associated protein (AIRAP), intrarenal MDR-1, MT-1, and AIRAP gene expression was enhanced to a similar extent in both strains, whereas NaAs challenge augmented intrarenal MRP-1 mRNA and protein expression levels in C57BL/6 but not BALB/c mice. Moreover, the administration of a specific inhibitor of MRP-1, MK-571, significantly exaggerated acute renal injury in C57BL/6 mice. Thus, MRP-1 is crucially involved in arsenic efflux and eventually prevention of acute renal injury upon acute exposure to NaAs.

  20. Radioprotection of 1,2-dimethylhydrazine-initiated colon cancer in rats using low-dose γ rays by modulating multidrug resistance-1, cytokeratin 20, and β-catenin expression.

    PubMed

    Nabil, H M; Hassan, B N; Tohamy, A A; Waaer, H F; Abdel Moneim, A E

    2016-03-01

    Ionizing radiation is a widely used therapy for solid tumors. However, high-dose ionizing radiation causes apoptosis, transforms normal cells into tumor cells, and impairs immune functions, leading to the defects in the removal of damaged or tumor cells. In contrast, low-dose radiation has been reported to exert various beneficial effects in cells. This experimental study investigated the effect of γ rays at low dose on the development of colorectal tumor in a 1,2-dimethylhydrazine (DMH)-induced colon cancer. Colorectal tumor model was induced in Wistar rats by subcutaneous injection of DMH (20 mg/kg) once a week for 15 weeks. Starting from zero day of DMH injection, a single low dose of whole-body γ irradiation of 0.5 Gy/week was applied to the rats. A significant reduction in lipid peroxidation, nitric oxide, and elevation in the glutathione content and antioxidant enzyme activity (superoxide dismutase and catalase) were observed after γ irradiation comparing with DMH group. Moreover, γ ray reduced the expressions of multidrug resistance 1 (MDR1), β-catenin, and cytokeratin 20 (CK20) those increased in DMH-treated rats. However, survivin did not change with γ ray treatment. A histopathological examination of the DMH-injected rats revealed ulcerative colitis, dysplasia, anaplasia, and hyperchromasia. An improvement in the histopathological picture was seen in the colon of rats exposed to γ rays. In conclusion, the present results showed that low-dose γ ray significantly inhibited DMH-induced colon carcinogenesis in rats by modulating CK20, MDR1, and β-catenin expression but not survivin expression.

  1. PEG-PE-based micelles co-loaded with paclitaxel and cyclosporine A or loaded with paclitaxel and targeted by anticancer antibody overcome drug resistance in cancer cells.

    PubMed

    Sarisozen, Can; Vural, Imran; Levchenko, Tatyana; Hincal, A Atilla; Torchilin, Vladimir P

    2012-05-01

    The over-expression of the P-glycoprotein (P-gp) in cancer cells is one of the main reasons of the acquired Multidrug Resistance (MDR). Combined treatment of MDR cancer cells with P-gp inhibitors and chemotherapeutic agents could result in reversal of resistance in P-gp-expressing cells. In this study, paclitaxel (PTX) was co-encapsulated in actively targeted (anticancer mAb 2C5-modified) polymeric lipid-core PEG-PE-based micelles with Cyclosporine A (CycA), which is one of the most effective first generation P-gp inhibitors. Cell culture studies performed using MDCKII (parental and MDR1) cell lines to investigate the potential MDR reversal effect of the formulations. The average size of both empty and loaded PEG₂₀₀₀-PE/Vitamin E mixed micelles was found between 10 and 25 nm. Zeta potentials of the formulations were found between -7 and -35 mV. The percentage of PTX in the micelles was found higher than 3% for both formulations and cumulative PTX release of about 70% was demonstrated. P-gp inhibition with CycA caused an increase in the cytotoxicity of PTX. Dual-loaded micelles demonstrated significantly higher cytotoxicity in the resistant MDCKII-MDR1 cells than micelles loaded with PTX alone. Micelle modification with mAb 2C5 results in the highest cytotoxicity against resistant cells, with or without P-gp modulator, probably because of better internalization bypassing the P-gp mechanism. Our results suggest that micelles delivering a combination of P-gp modulator and anticancer drug or micelles loaded with only PTX, but targeted with mAb 2C5 represent a promising approach to overcome drug resistance in cancer cells. PMID:22506922

  2. Long-circulating PEG-PE micelles co-loaded with paclitaxel and elacridar (GG918) overcome multidrug resistance.

    PubMed

    Sarisozen, Can; Vural, Imran; Levchenko, Tatyana; Hincal, A Atilla; Torchilin, Vladimir P

    2012-11-01

    Overexpression of drug efflux pump P-gp is one of the major reasons to cause multidrug resistance (MDR). To overcome P-gp mediated MDR, modulators, so called P-gp inhibitors, can be used to block efflux pump activity. Elacridar is one of the most potent P-gp inhibitors, which can cause irreversible and total P-gp blockage. Elacridar, among with other P-gp inhibitors, can be used in combination with anticancer drugs to enhance the effectiveness of chemotherapy against resistant tumor cells. On the other hand, P-gp is presented in normal tissues, thus non-selective blockage of P-gp can cause undesired side effects. Therefore, it is important to deliver P-gp inhibitor only to the tumor cells (along with anticancer drug) and limit its distribution in the body. In this study, we have developed PEG-PE-based long-circulating ca. 15 nm micelles co-loaded with elacridar and paclitaxel, and investigated their ability to overcome paclitaxel resistance in two cancer cell lines. Vitamin E, a common solubility enhancer for PEG-PE micelles, was found to have a negative effect on both particle size and encapsulation efficiencies. The human MDR1 gene-transfected and thus paclitaxel-resistant MDCKII-MDR1 P-gp overexpressing cells were used for cytotoxicity evaluation. Even though PEG-PE based micelles itself have a potential to enhance the cytotoxicity of paclitaxel, elacridar/paclitaxel-co-loaded micelles demonstrated the highest cytotoxicity compared to both free and micellar paclitaxel. The obtained results suggest that co-loading of paclitaxel and elacridar into micellar drug carriers results in promising preparations capable of overcoming paclitaxel resistance. PMID:23030458

  3. TSPO Ligand-Methotrexate Prodrug Conjugates: Design, Synthesis, and Biological Evaluation

    PubMed Central

    Laquintana, Valentino; Denora, Nunzio; Cutrignelli, Annalisa; Perrone, Mara; Iacobazzi, Rosa Maria; Annese, Cosimo; Lopalco, Antonio; Lopedota, Angela Assunta; Franco, Massimo

    2016-01-01

    The 18-kDa translocator protein (TSPO) is a potential mitochondrial target for drug delivery to tumors overexpressing TSPO, including brain cancers, and selective TSPO ligands have been successfully used to selectively deliver drugs into the target. Methotrexate (MTX) is an anticancer drug of choice for the treatment of several cancers, but its permeability through the blood brain barrier (BBB) is poor, making it unsuitable for the treatment of brain tumors. Therefore, in this study, MTX was selected to achieve two TSPO ligand-MTX conjugates (TSPO ligand α-MTX and TSPO ligand γ-MTX), potentially useful for the treatment of TSPO-rich cancers, including brain tumors. In this work, we have presented the synthesis, the physicochemical characterizations, as well as the in vitro stabilities of the new TSPO ligand-MTX conjugates. The binding affinity for TSPO and the selectivity versus central-type benzodiazepine receptor (CBR) was also investigated. The cytotoxicity of prepared conjugates was evaluated on MTX-sensitive human and rat glioma cell lines overexpressing TSPO. The estimated coefficients of lipophilicity and the stability studies of the conjugates confirm that the synthesized molecules are stable enough in buffer solution at pH 7.4, as well in physiological medium, and show an increased lipophilicity compared to the MTX, compatible with a likely ability to cross the blood brain barrier. The latter feature of two TSPO ligand-MTX conjugates was also confirmed by in vitro permeability studies conducted on Madin-Darby canine kidney cells transfected with the human MDR1 gene (MDCK-MDR1) monolayers. TSPO ligand-MTX conjugates have shown to possess a high binding affinity for TSPO, with IC50 values ranging from 7.2 to 40.3 nM, and exhibited marked toxicity against glioma cells overexpressing TSPO, in comparison with the parent drug MTX. PMID:27322261

  4. TFPI1 Mediates Resistance to Doxorubicin in Breast Cancer Cells by Inducing a Hypoxic-Like Response

    PubMed Central

    Davies, Gerald F.; Berg, Arnie; Postnikoff, Spike D. L.; Wilson, Heather L.; Arnason, Terra G.; Kusalik, Anthony; Harkness, Troy A. A.

    2014-01-01

    Thrombin and hypoxia are important players in breast cancer progression. Breast cancers often develop drug resistance, but mechanisms linking thrombin and hypoxia to drug resistance remain unresolved. Our studies using Doxorubicin (DOX) resistant MCF7 breast cancer cells reveals a mechanism linking DOX exposure with hypoxic induction of DOX resistance. Global expression changes between parental and DOX resistant MCF7 cells were examined. Westerns, Northerns and immunocytochemistry were used to validate drug resistance and differentially expressed genes. A cluster of genes involved in the anticoagulation pathway, with Tissue Factor Pathway Inhibitor 1 (TFPI1) the top hit, was identified. Plasmids overexpressing TFPI1 were utilized, and 1% O2 was used to test the effects of hypoxia on drug resistance. Lastly, microarray datasets from patients with drug resistant breast tumors were interrogated for TFPI1 expression levels. TFPI1 protein levels were found elevated in 3 additional DOX resistant cells lines, from humans and rats, indicating evolutionarily conservation of the effect. Elevated TFPI1 in DOX resistant cells was active, as thrombin protein levels were coincidentally low. We observed elevated HIF1α protein in DOX resistant cells, and in cells with forced expression of TFPI1, suggesting TFPI1 induces HIF1α. TFPI1 also induced c-MYC, c-SRC, and HDAC2 protein, as well as DOX resistance in parental cells. Growth of cells in 1% O2 induced elevated HIF1α, BCRP and MDR-1 protein, and these cells were resistant to DOX. Our in vitro results were consistent with in vivo patient datasets, as tumors harboring increased BCRP and MDR-1 expression also had increased TFPI1 expression. Our observations are clinically relevant indicating that DOX treatment induces an anticoagulation cascade, leading to inhibition of thrombin and the expression of HIF1α. This in turn activates a pathway leading to drug resistance. PMID:24489651

  5. Pharmacokinetic comparison to determine the mechanisms underlying the differential efficacies of cationic diamidines against first- and second-stage human African trypanosomiasis.

    PubMed

    Yang, Sihyung; Wenzler, Tanja; Miller, Patrik N; Wu, Huali; Boykin, David W; Brun, Reto; Wang, Michael Zhuo

    2014-07-01

    Human African trypanosomiasis (HAT), a neglected tropical disease, is fatal without treatment. Pentamidine, a cationic diamidine, has been used to treat first-stage (hemolymphatic) HAT since the 1940s, but it is ineffective against second-stage (meningoencephalitic, or central nervous system [CNS]) infection. Novel diamidines (DB75, DB820, and DB829) have shown promising efficacy in both mouse and monkey models of first-stage HAT. However, only DB829 cured animals with second-stage infection. In this study, we aimed to determine the mechanisms underlying the differential efficacies of these diamidines against HAT by conducting a comprehensive pharmacokinetic characterization. This included the determination of metabolic stability in liver microsomes, permeability across MDCK and MDR1-MDCK cell monolayers, interaction with the efflux transporter MDR1 (P-glycoprotein 1 or P-gp), drug binding in plasma and brain, and plasma and brain concentration-time profiles after a single dose in mice. The results showed that DB829, an azadiamidine, had the highest systemic exposure and brain-to-plasma ratio, whereas pentamidine and DB75 had the lowest. None of these diamidines was a P-gp substrate, and the binding of each to plasma proteins and brain differed greatly. The brain-to-plasma ratio best predicted the relative efficacies of these diamidines in mice with second-stage infection. In conclusion, pharmacokinetics and CNS penetration influenced the in vivo efficacies of cationic diamidines against first- and second-stage HAT and should be considered when developing CNS-active antitrypanosomal diamidines.

  6. TSPO Ligand-Methotrexate Prodrug Conjugates: Design, Synthesis, and Biological Evaluation.

    PubMed

    Laquintana, Valentino; Denora, Nunzio; Cutrignelli, Annalisa; Perrone, Mara; Iacobazzi, Rosa Maria; Annese, Cosimo; Lopalco, Antonio; Lopedota, Angela Assunta; Franco, Massimo

    2016-01-01

    The 18-kDa translocator protein (TSPO) is a potential mitochondrial target for drug delivery to tumors overexpressing TSPO, including brain cancers, and selective TSPO ligands have been successfully used to selectively deliver drugs into the target. Methotrexate (MTX) is an anticancer drug of choice for the treatment of several cancers, but its permeability through the blood brain barrier (BBB) is poor, making it unsuitable for the treatment of brain tumors. Therefore, in this study, MTX was selected to achieve two TSPO ligand-MTX conjugates (TSPO ligand α-MTX and TSPO ligand γ-MTX), potentially useful for the treatment of TSPO-rich cancers, including brain tumors. In this work, we have presented the synthesis, the physicochemical characterizations, as well as the in vitro stabilities of the new TSPO ligand-MTX conjugates. The binding affinity for TSPO and the selectivity versus central-type benzodiazepine receptor (CBR) was also investigated. The cytotoxicity of prepared conjugates was evaluated on MTX-sensitive human and rat glioma cell lines overexpressing TSPO. The estimated coefficients of lipophilicity and the stability studies of the conjugates confirm that the synthesized molecules are stable enough in buffer solution at pH 7.4, as well in physiological medium, and show an increased lipophilicity compared to the MTX, compatible with a likely ability to cross the blood brain barrier. The latter feature of two TSPO ligand-MTX conjugates was also confirmed by in vitro permeability studies conducted on Madin-Darby canine kidney cells transfected with the human MDR1 gene (MDCK-MDR1) monolayers. TSPO ligand-MTX conjugates have shown to possess a high binding affinity for TSPO, with IC50 values ranging from 7.2 to 40.3 nM, and exhibited marked toxicity against glioma cells overexpressing TSPO, in comparison with the parent drug MTX. PMID:27322261

  7. pH dependent but not P-gp dependent bidirectional transport study of S-propranolol: the importance of passive diffusion

    PubMed Central

    Zheng, Yi; Benet, Leslie Z.; Okochi, Hideaki; Chen, Xijing

    2016-01-01

    Purpose Recent controversial publications, citing studies purporting to show that P-gp mediates the transport of propranolol, proposed that passive biological membrane transport is negligible. Based on the BDDCS, the extensively metabolized-highly permeable-highly soluble BDDCS class 1 drug, propranolol, shows a high passive permeability at concentrations unrestricted by solubility that can overwhelm any potential transporter effects. Here we reinvestigate the effects of passive diffusion and carrier-mediated transport on S-propranolol. Methods Bidirectional permeability and inhibition of efflux transport studies were carried out in MDCK, MDCK-MDR1 and Caco-2 cell lines at different concentrations. Transcellular permeability studies were conducted at different apical pHs in the rat jejunum Ussing chamber model and PAMPA system. Results S-propranolol exhibited efflux ratios lower than 1 in MDCK, MDCK-MDR1 and Caco-2 cells. No significant differences of Papp, B->A in the presence and absence of the efflux inhibitor GG918 were observed. However, an efflux ratio of 3.63 was found at apical pH 6.5 with significant decrease in Papp, A->B and increase in Papp, B->A compared to apical pH 7.4 in Caco-2 cell lines. The pH dependent permeability was confirmed in the Ussing chamber model. S-propranolol flux was unchanged during inhibition by verapamil and rifampin. Furthermore, pH dependent permeability was also observed in the PAMPA system. Conclusions S-propranolol does not exhibit active transport as proposed previously. The "false" positive efflux ratio can be explained by the pH partition theory. As expected, passive diffusion, but not active transport, plays the primary role in the permeability of the BDDCS class 1 drug propranolol. PMID:25690341

  8. P-glycoprotein is expressed and causes resistance to chemotherapy in EBV-positive T-cell lymphoproliferative diseases.

    PubMed

    Yoshimori, Mayumi; Takada, Honami; Imadome, Ken-Ichi; Kurata, Morito; Yamamoto, Kouhei; Koyama, Takatoshi; Shimizu, Norio; Fujiwara, Shigeyoshi; Miura, Osamu; Arai, Ayako

    2015-10-01

    Epstein-Barr virus-positive T-cell lymphoproliferative diseases (EBV-T-LPDs) are rare lymphomas with poor prognosis. Although chemotherapeutic strategies such as CHOP have been often selected, they have exhibited only limited efficacy. To clarify the mechanism of chemoresistance, we examined P-glycoprotein (P-gp) expression. P-gp acts as an energy-dependent efflux pump that excretes drugs from the cytoplasm, resulting in low-intracellular drug concentrations and poor sensitivity to chemotherapy. We examined P-gp expression in EBV-positive cells by immunohistochemistry staining in three patients of EBV-T-LPDs and the expression was detected in all patients. We also examined mdr1 mRNA expression by reverse-transcriptase polymerase-chain reaction (RT-PCR) in EBV-positive tumor cells from these patients and additional three patients. The expression was detected in all examined patients. In five EBV-T-LPDs patients, P-gp function was detected by Rhodamine-123 efflux assay in these cells. The efflux was inhibited by treatment with a P-gp inhibitor, cyclosporine A (CsA). We also examined and detected P-gp expression in EBV-positive T-cell lines SNT8 and SNT16 established from EBV-T-LPDs patients, by RT-PCR and western blotting. The function was also detected by Rhodamine-123 efflux in these cell lines. Inhibition and knock down of P-gp by CsA and siRNA, respectively, enhanced etoposide- and doxorubicin-induced cell death in the EBV-positive T-cell lines. Finally, we infected the T-cell line MOLT4 with EBV, and found that mdr1 mRNA expression and Rhodamine 123 efflux were upregulated after infection. These results indicated that enhanced P-gp expression contributed to the chemoresistance of EBV-T-LPDs.

  9. Modulation of P-glycoprotein function and multidrug resistance in cancer cells by Thai plant extracts.

    PubMed

    Takano, M; Kakizoe, S; Kawami, M; Nagai, J; Patanasethnont, D; Sripanidkulchai, B; Yumoto, R

    2014-11-01

    The effects of ethanol extracts from Thai plants belonging to the families of Annonaceae, Rutaceae, and Zingiberaceae on P-glycoprotein (P-gp) function and multidrug resistance were examined in paclitaxel-resistant HepG2 (PR-HepG2) cells. All the extracts tested, significantly increased the accumulation of [3H]paclitaxel, a P-gp substrate, in the cells. Among nine extracts, Z01 and Z02, extracts from Curcuma comosa and Kaempferia marginata (Zingiberaceae family), respectively, potently increased the accumulation. In addition, Z01 and Z02 increased the accumulation of other P-gp substrates, rhodamine 123 and doxorubicin, in PR-HepG2 cells in a concentration-dependent manner. Increased accumulation of rhodamine 123 and doxorubicin by Z01 and Z02 was also confirmed by confocal laser scanning microscopy. The effect of Z01 and Z02 pretreatment on the expression of MDR1 mRNA was also examined. The expression of MDR1 mRNA was not affected by the treatment of PR-HepG2 cells with these extracts for 48 hours. Cytotoxicity of paclitaxel was examined by XTT and protein assays in the absence and presence of Z02. Z02 potentiated the cytotoxicity of paclitaxel in PR-HepG2 cells. These results suggest that Curcuma comosa and Kaempferia marginata belonging to Zingiberaceae are useful sources to search for new P-gp modulator(s) that can be used to overcome multidrug resistance of cancer cells.

  10. Thiazide-like diuretic drug metolazone activates human pregnane X receptor to induce cytochrome 3A4 and multidrug-resistance protein 1

    PubMed Central

    Banerjee, Monimoy; Chen, Taosheng

    2014-01-01

    Human pregnane X receptor (hPXR) regulates the expression of drug-metabolizing enzyme cytochrome P450 3A4 (CYP3A4) and drug transporters such as multidrug-resistance protein 1 (MDR1). PXR can be modulated by small molecules, including Federal Drug Administration (FDA)–approved drugs, thus altering drug metabolism and causing drug-drug interactions. To determine the role of FDA-approved drugs in PXR-mediated regulation of drug metabolism and clearance, we screened 1481 FDA-approved small-molecule drugs by using a luciferase reporter assay in HEK293T cells and identified the diuretic drug metolazone as an activator of PXR. Our data showed that metolazone activated hPXR-mediated expression of CYP3A4 and MDR1 in human hepatocytes and intestine cells and increased CYP3A4 promoter activity in various cell lines. Mammalian two-hybrid assays showed that hPXR recruits its co-activator SRC-1 upon metolazone binding in HepG2 cells, explaining the mechanism of hPXR activation. To understand the role of other commonly-used diuretics in PXR activation and the structure-activity relationship of metolazone, thiazide and non-thiazide diuretics drugs were also tested but only metolazone activates PXR. To understand the molecular mechanism, docking studies and mutational analysis were carried out and showed that metolazone binds in the ligand-binding pocket and interacts with mostly hydrophobic amino acid residues. This is the first report showing that metolazone activates PXR. Because activation of hPXR might cause drug-drug interactions, metolazone should be used with caution for drug treatment in patients undergoing combination therapy. PMID:25181459

  11. Role of ABC and Solute Carrier Transporters in the Placental Transport of Lamivudine.

    PubMed

    Ceckova, Martina; Reznicek, Josef; Ptackova, Zuzana; Cerveny, Lukas; Müller, Fabian; Kacerovsky, Marian; Fromm, Martin F; Glazier, Jocelyn D; Staud, Frantisek

    2016-09-01

    Lamivudine is one of the antiretroviral drugs of choice for the prevention of mother-to-child transmission (MTCT) in HIV-positive women. In this study, we investigated the relevance of drug efflux transporters P-glycoprotein (P-gp) (MDR1 [ABCB1]), BCRP (ABCG2), MRP2 (ABCC2), and MATE1 (SLC47A1) for the transmembrane transport and transplacental transfer of lamivudine. We employed in vitro accumulation and transport experiments on MDCK cells overexpressing drug efflux transporters, in situ-perfused rat term placenta, and vesicular uptake in microvillous plasma membrane (MVM) vesicles isolated from human term placenta. MATE1 significantly accelerated lamivudine transport in MATE1-expressing MDCK cells, whereas no transporter-driven efflux of lamivudine was observed in MDCK-MDR1, MDCK-MRP2, and MDCK-BCRP monolayers. MATE1-mediated efflux of lamivudine appeared to be a low-affinity process (apparent Km of 4.21 mM and Vmax of 5.18 nmol/mg protein/min in MDCK-MATE1 cells). Consistent with in vitro transport studies, the transplacental clearance of lamivudine was not affected by P-gp, BCRP, or MRP2. However, lamivudine transfer across dually perfused rat placenta and the uptake of lamivudine into human placental MVM vesicles revealed pH dependency, indicating possible involvement of MATE1 in the fetal-to-maternal efflux of the drug. To conclude, placental transport of lamivudine does not seem to be affected by P-gp, MRP2, or BCRP, but a pH-dependent mechanism mediates transport of lamivudine in the fetal-to-maternal direction. We suggest that MATE1 might be, at least partly, responsible for this transport. PMID:27401571

  12. Reversal of multidrug resistance of hepatocellular carcinoma cells by metformin through inhibiting NF-κB gene transcription

    PubMed Central

    Wu, Wei; Yang, Jun-Ling; Wang, Yi-Lang; Wang, Han; Yao, Min; Wang, Li; Gu, Juan-Juan; Cai, Yin; Shi, Yun; Yao, Deng-Fu

    2016-01-01

    AIM To interfere with the activation of nuclear factor-κB (NF-κB) with metformin and explore its effect in reversing multidrug resistance (MDR) of hepatocellular carcinoma (HCC) cells. METHODS Expression of P-glycoprotein (P-gp) and NF-κB in human HepG2 or HepG2/adriamycin (ADM) cells treated with pCMV-NF-κB-small interference RNA (siRNA) with or without metformin, was analyzed by Western blot or fluorescence quantitative PCR. Cell viability was tested by CCK-8 assay. Cell cycle and apoptosis were measured by flow cytometry and Annexin-V-PE/7-AnnexinV apoptosis detection double staining assay, respectively. RESULTS P-gp overexpression in HepG2 and HepG2/ADM cells was closely related to mdr1 mRNA (3.310 ± 0.154) and NF-κB mRNA (2.580 ± 0.040) expression. NF-κB gene transcription was inhibited by specific siRNA with significant down-regulation of P-gp and enhanced HCC cell chemosensitivity to doxorubicin. After pretreatment with metformin, HepG2/ADM cells were sensitized to doxorubicin and P-gp was decreased through the NF-κB signaling pathway. The synergistic effect of metformin and NF-κB siRNA were found in HepG2/ADM cells with regard to proliferation inhibition, cell cycle arrest and inducing cell apoptosis. CONCLUSION Metformin via silencing NF-κB signaling could effectively reverse MDR of HCC cells by down-regulating MDR1/P-gp expression. PMID:27621764

  13. TSPO Ligand-Methotrexate Prodrug Conjugates: Design, Synthesis, and Biological Evaluation.

    PubMed

    Laquintana, Valentino; Denora, Nunzio; Cutrignelli, Annalisa; Perrone, Mara; Iacobazzi, Rosa Maria; Annese, Cosimo; Lopalco, Antonio; Lopedota, Angela Assunta; Franco, Massimo

    2016-06-18

    The 18-kDa translocator protein (TSPO) is a potential mitochondrial target for drug delivery to tumors overexpressing TSPO, including brain cancers, and selective TSPO ligands have been successfully used to selectively deliver drugs into the target. Methotrexate (MTX) is an anticancer drug of choice for the treatment of several cancers, but its permeability through the blood brain barrier (BBB) is poor, making it unsuitable for the treatment of brain tumors. Therefore, in this study, MTX was selected to achieve two TSPO ligand-MTX conjugates (TSPO ligand α-MTX and TSPO ligand γ-MTX), potentially useful for the treatment of TSPO-rich cancers, including brain tumors. In this work, we have presented the synthesis, the physicochemical characterizations, as well as the in vitro stabilities of the new TSPO ligand-MTX conjugates. The binding affinity for TSPO and the selectivity versus central-type benzodiazepine receptor (CBR) was also investigated. The cytotoxicity of prepared conjugates was evaluated on MTX-sensitive human and rat glioma cell lines overexpressing TSPO. The estimated coefficients of lipophilicity and the stability studies of the conjugates confirm that the synthesized molecules are stable enough in buffer solution at pH 7.4, as well in physiological medium, and show an increased lipophilicity compared to the MTX, compatible with a likely ability to cross the blood brain barrier. The latter feature of two TSPO ligand-MTX conjugates was also confirmed by in vitro permeability studies conducted on Madin-Darby canine kidney cells transfected with the human MDR1 gene (MDCK-MDR1) monolayers. TSPO ligand-MTX conjugates have shown to possess a high binding affinity for TSPO, with IC50 values ranging from 7.2 to 40.3 nM, and exhibited marked toxicity against glioma cells overexpressing TSPO, in comparison with the parent drug MTX.

  14. Methylation of WTH3, a possible drug resistant gene, inhibits p53 regulated expression

    PubMed Central

    Tian, Kegui; Wang, Yuezeng; Huang, Yu; Sun, Boqiao; Li, Yuxin; Xu, Haopeng

    2008-01-01

    Background Previous results showed that over-expression of the WTH3 gene in MDR cells reduced MDR1 gene expression and converted their resistance to sensitivity to various anticancer drugs. In addition, the WTH3 gene promoter was hypermethylated in the MCF7/AdrR cell line and primary drug resistant breast cancer epithelial cells. WTH3 was also found to be directly targeted and up regulated by the p53 gene. Furthermore, over expression of the WTH3 gene promoted the apoptotic phenotype in various host cells. Methods To further confirm WTH3's drug resistant related characteristics, we recently employed the small hairpin RNA (shRNA) strategy to knockdown its expression in HEK293 cells. In addition, since the WTH3 promoter's p53-binding site was located in a CpG island that was targeted by methylation, we were interested in testing the possible effect this epigenetic modification had on the p53 transcription factor relative to WTH3 expression. To do so, the in vitro methylation method was utilized to examine the p53 transgene's influence on either the methylated or non-methylated WTH3 promoter. Results The results generated from the gene knockdown strategy showed that reduction of WTH3 expression increased MDR1 expression and elevated resistance to Doxorubicin as compared to the original control cells. Data produced from the methylation studies demonstrated that DNA methylation adversely affected the positive impact of p53 on WTH3 promoter activity. Conclusion Taken together, our studies provided further evidence that WTH3 played an important role in MDR development and revealed one of its transcription regulatory mechanisms, DNA methylation, which antagonized p53's positive impact on WTH3 expression. PMID:18992151

  15. Isolation and characterization of an IGROV-1 human ovarian cancer cell line made resistant to Ecteinascidin-743 (ET-743)

    PubMed Central

    Erba, E; Bergamaschi, D; Bassano, L; Ronzoni, S; Liberti, G Di; Muradore, I; Vignati, S; Faircloth, G; Jimeno, J; D'Incalci, M

    2000-01-01

    By exposing Igrov-1 human ovarian cancer cells to increasing concentrations of Ecteinascidin-743 (ET-743), either for a short or prolonged time, we obtained sublines resistant to ET-743 which overexpress Pgp. The most resistant clone (Igrov-1/25 ET) was evaluated for biological and pharmacological characterizations. The increased Pgp levels of Igrov-1/25 ET were not due to amplification of the mdr-1 gene but to increased mRNA levels. No increase in other multidrug resistance-related proteins such as MRP or LRP was observed in Igrov-1/25 ET. The IC50values of ET-743 against Igrov-1/25 ET was approximately 50 times higher than the parental cell line. Resistance was not reversed while maintaining the cell line in drug-free medium for at least 24 months. Igrov-1/25 ET was cross-resistant to Doxorubicin and VP16 while it was equally sensitive to L-PAM, MNNG, CPT and only marginally less sensitive to Cis-DDP and Oxaliplatin compared to the parental cell line. Igrov-1/25 ET exposed to Doxorubicin retained this drug much less, mainly because of a more efficient drug efflux. The cyclosporine analogue SDZ PSC-833 reversed the resistance of Igrov-1/25 ET to ET-743, without any enhancement of the drug activity against the parental Igrov-1 cell line. Igrov-1/25 ET exhibits typical features of cell lines overexpressing the mdr-1 gene and can be a potentially useful tool in selecting ET-743 non-cross-resistant analogues as well as to investigate methods to counteract resistance to this drug. © 2000 Cancer Research Campaign PMID:10817511

  16. Induction of apoptosis in colon cancer cells by a novel topoisomerase I inhibitor TopIn

    SciTech Connect

    Bae, Soo Kyung; Gwak, Jungsug; Song, Im-Sook; Park, Hyung-Soon; Oh, Sangtaek

    2011-05-27

    Highlights: {yields} TopIn activates p53-dependent transcription in colon cancer cells. {yields} TopIn induces apoptosis in colon cancer cells. {yields} TopIn selectively inhibits topoisomerase I activity. {yields} TopIn does not affect the activity of BCRP and MDR-1. -- Abstract: The tumor suppressor p53 plays an important role in cellular emergency mechanisms through regulating the genes involved in cell cycle arrest and apoptosis. To identify small molecules that can activate p53-responsive transcription, we performed chemical screening using genetically engineered HCT116 reporter cells. We found that TopIn (7-phenyl-6H-[1,2,5]oxadiazolo[3,4-e]indole 3-oxide) efficiently activated p53-mediated transcriptional activity and induced phosphorylation of p53 at Ser15, thereby stabilizing the p53 protein. Furthermore, TopIn upregulated the expression of p21{sup WAF1/CIP1}, a downstream target of p53, and suppressed cellular proliferation in various colon cancer cells. Additionally, TopIn induced DNA fragmentation, caspase-3/7 activation and poly ADP ribose polymerase cleavage, typical biochemical markers of apoptosis, in p53 wild-type and mutated colon cancer cells. Finally, we found that TopIn inhibited topoisomerase I activity, but not topoisomerase II, in vitro and induced the formation of the topoisomerase I-DNA complex in HCT116 colon cancer cells. Unlike camptothecin (CPT) and its derivative SN38, TopIn did not affect the activity of the ATP-binding cassette transporter breast cancer resistance protein (BCRP) or multidrug-resistant protein-1 (MDR-1). These results suggest that TopIn may present a promising new topoisomerase I-targeting anti-tumor therapeutics.

  17. Overexpression and mutation as a genetic mechanism of fluconazole resistance in Candida albicans isolated from human immunodeficiency virus patients in Indonesia.

    PubMed

    Rosana, Yeva; Yasmon, Andi; Lestari, Delly Chipta

    2015-09-01

    Fluconazole is the standard treatment for oropharyngeal candidiasis, which is the third most common opportunistic infection in human immunodeficiency virus (HIV)/AIDS patients in Indonesia. Overuse of this drug could lead to the emergence of resistance. The objective of this study was to analyse the role of ERG11, CDR1, CDR2 and MDR1 gene overexpression and mutations in the ERG11 gene as a genetic mechanism of fluconazole resistance in Candida albicans isolated from HIV patients in Indonesia. Overexpression of ERG11, CDR1, CDR2 and MDR1 was analysed by real-time reverse transcription PCR, while ERG11 gene mutation analysis was performed using sequencing methods. Seventeen isolates out of 92 strains of C. albicans isolated from 108 HIV patients were found to be resistant to azole antifungals. The highest gene overexpression of ERG11 was found in C. albicans resistant to single fluconazole, while the highest gene overexpression of CDR2 was detected in all isolates of C. albicans resistant to multiple azoles. Amino acid substitutions were observed at six positions, i.e. D116E, D153E, I261V, E266D, V437I and V488I. The amino acid substitution I261V was identified in this study and was probably associated with fluconazole resistance. The combination of overexpression of CDR2 and ERG11 and mutation in the ERG11 gene was found to be a genetic mechanism of fluconazole resistance in C. albicans isolated from HIV patients in Indonesia. PMID:26297039

  18. Candida parapsilosis Resistance to Fluconazole: Molecular Mechanisms and In Vivo Impact in Infected Galleria mellonella Larvae.

    PubMed

    Souza, Ana Carolina R; Fuchs, Beth Burgwyn; Pinhati, Henrique M S; Siqueira, Ricardo A; Hagen, Ferry; Meis, Jacques F; Mylonakis, Eleftherios; Colombo, Arnaldo L

    2015-10-01

    Candida parapsilosis is the main non-albicans Candida species isolated from patients in Latin America. Mutations in the ERG11 gene and overexpression of membrane transporter proteins have been linked to fluconazole resistance. The aim of this study was to evaluate the molecular mechanisms in fluconazole-resistant strains of C. parapsilosis isolated from critically ill patients. The identities of the nine collected C. parapsilosis isolates at the species level were confirmed through molecular identification with a TaqMan qPCR assay. The clonal origin of the strains was checked by microsatellite typing. The Galleria mellonella infection model was used to confirm in vitro resistance. We assessed the presence of ERG11 mutations, as well as the expression of ERG11 and two additional genes that contribute to antifungal resistance (CDR1 and MDR1), by using real-time quantitative PCR. All of the C. parapsilosis (sensu stricto) isolates tested exhibited fluconazole MICs between 8 and 16 μg/ml. The in vitro data were confirmed by the failure of fluconazole in the treatment of G. mellonella infected with fluconazole-resistant strains of C. parapsilosis. Sequencing of the ERG11 gene revealed a common mutation leading to a Y132F amino acid substitution in all of the isolates, a finding consistent with their clonal origin. After fluconazole exposure, overexpression was noted for ERG11, CDR1, and MDR1 in 9/9, 9/9, and 2/9 strains, respectively. We demonstrated that a combination of molecular mechanisms, including the presence of point mutations in the ERG11 gene, overexpression of ERG11, and genes encoding efflux pumps, are involved in fluconazole resistance in C. parapsilosis.

  19. Molecular mechanisms associated with Fluconazole resistance in clinical Candida albicans isolates from India.

    PubMed

    Mane, Arati; Vidhate, Pallavi; Kusro, Chanchal; Waman, Vaishali; Saxena, Vandana; Kulkarni-Kale, Urmila; Risbud, Arun

    2016-02-01

    Resistance to azole antifungals is a significant problem in Candida albicans. An understanding of resistance at molecular level is essential for the development of strategies to tackle resistance and rationale design of newer antifungals and target-based molecular approaches. This study presents the first evaluation of molecular mechanisms associated with fluconazole resistance in clinical C.albicans isolates from India. Target site (ERG11) alterations were determined by DNA sequencing, whereas real-time PCRs were performed to quantify target and efflux pump genes (CDR1, CDR2, MDR1) in 87 [Fluconazole susceptible (n = 30), susceptible-dose dependent (n = 30) and resistant (n = 27)] C.albicans isolates. Cross-resistance to fluconazole, ketoconazole and itraconazole was observed in 74.1% isolates. Six amino acid substitutions were identified, including 4 (E116D, F145L, E226D, I437V) previously reported ones and 2 (P406L, Q474H) new ones. CDR1 over-expression was seen in 77.7% resistant isolates. CDR2 was exclusively expressed with CDR1 and their concomitant over-expression was associated with azole cross-resistance. MDR1 and ERG11 over-expression did not seem to be associated with resistance. Our results show that drug efflux mediated by Adenosine-5'-triphosphate (ATP)-binding cassette transporters, especially CDR1 is the predominant mechanism of fluconazole resistance and azole cross-resistance in C. albicans and indicate the need for research directed towards developing strategies to tackle efflux mediated resistance to salvage azoles.

  20. Morphometric Analysis of Auxin-Mediated Development

    NASA Astrophysics Data System (ADS)

    Lewis, Daniel

    Auxin controls many aspects of plant development through its effects on growth. Its distribution is controlled by specific tissue and organ level polar transport streams. The responses to environmental cues such as gravity light, nutrient availability are largely controlled by coordinated regulation of distinct auxin transport streams. Many plant responses to the environment involve changes in shape. Much can be learned about the underlying processes controlling plant form if the response is measured with sufficient resolution. Computer-aided analysis of digital images or 'machine vision' can be used to greatly increase the speed and consistency of data from a morphometric study of plant form. Advances in image acquisition and analysis pioneered at UW-Madison have allowed unprecedented resolution of the growth and gravitropism of Arabidopsis. A reverse genetic analysis was used to determine if the MDR-like ABC transporters influence auxin distribution important for plant development and the response to environmental cues in Arabidopsis. Mutations in MDR1 (At3g28860) reduce acropetal auxin transport in the root. This is correlated with deviation from the vertical axis. Mutations in MDR4 (At2g47000) reduce basipetal auxin transport in the root. This is correlated with hypergravitropism. It was theorized that reduced transport whithin the elongation zone is responsible for the increased curvature. Flavanols were found to regulate gravitropism upstream of MDR4. The mdr1 mdr4 double mutant showed additive but not synergistic phenotypes, suggesting that the two auxin transport streams are more independent than interdependent. MDR proteins seem to enhance auxin transport in situations where PIN-type effux alone is insufficient.

  1. Tocotrienols activate the steroid and xenobiotic receptor, SXR, and selectively regulate expression of its target genes.

    PubMed

    Zhou, Changcheng; Tabb, Michelle M; Sadatrafiei, Asal; Grün, Felix; Blumberg, Bruce

    2004-10-01

    Vitamin E is an essential nutrient with antioxidant activity. Vitamin E is comprised of eight members, alpha-, beta-, gamma-, and delta-tocopherols and alpha-, beta-, gamma-, and delta-tocotrienols. All forms of vitamin E are initially metabolized by omega-oxidation, which is catalyzed by cytochrome P450 enzymes. The steroid and xenobiotic receptor (SXR) is a nuclear receptor that regulates drug clearance in the liver and intestine via induction of genes involved in drug and xenobiotic metabolism. We show here that all four tocotrienols specifically bind to and activate SXR, whereas tocopherols neither bind nor activate. Surprisingly, tocotrienols show tissue-specific induction of SXR target genes, particularly CYP3A4. Tocotrienols up-regulate expression of CYP3A4 but not UDP-glucuronosyltransferase 1A1 (UGT1A1) or multidrug resistance protein-1 (MDR1) in primary hepatocytes. In contrast, tocotrienols induce MDR1 and UGT1A1 but not CYP3A4 expression in intestinal LS180 cells. We found that nuclear receptor corepressor (NCoR) is expressed at relatively high levels in intestinal LS180 cells compared with primary hepatocytes. The unliganded SXR interacts with NCoR, and this interaction is only partially disrupted by tocotrienols. Expression of a dominant-negative NCoR enhanced the ability of tocotrienols to induce CYP3A4 in LS180 cells, suggesting that NCoR plays an important role in tissue-specific gene regulation by SXR. Our findings provide a molecular mechanism explaining how vitamin supplements affect the absorption and effectiveness of drugs. Knowledge of drug-nutrient interactions may help reduce the incidence of decreased drug efficacy. PMID:15269186

  2. Defective canalicular transport and toxicity of dietary ursodeoxycholic acid in the abcb11-/- mouse: transport and gene expression studies.

    PubMed

    Wang, Renxue; Liu, Lin; Sheps, Jonathan A; Forrest, Dana; Hofmann, Alan F; Hagey, Lee R; Ling, Victor

    2013-08-15

    The bile salt export pump (BSEP), encoded by the abcb11 gene, is the major canalicular transporter of bile acids from the hepatocyte. BSEP malfunction in humans causes bile acid retention and progressive liver injury, ultimately leading to end-stage liver failure. The natural, hydrophilic, bile acid ursodeoxycholic acid (UDCA) is efficacious in the treatment of cholestatic conditions, such as primary biliary cirrhosis and cholestasis of pregnancy. The beneficial effects of UDCA include promoting bile flow, reducing hepatic inflammation, preventing apoptosis, and maintaining mitochondrial integrity in hepatocytes. However, the role of BSEP in mediating UDCA efficacy is not known. Here, we used abcb11 knockout mice (abcb11-/-) to test the effects of acute and chronic UDCA administration on biliary secretion, bile acid composition, liver histology, and liver gene expression. Acutely infused UDCA, or its taurine conjugate (TUDC), was taken up by the liver but retained, with negligible biliary output, in abcb11-/- mice. Feeding UDCA to abcb11-/- mice led to weight loss, retention of bile acids, elevated liver enzymes, and histological damage to the liver. Semiquantitative RT-PCR showed that genes encoding Mdr1a and Mdr1b (canalicular) as well as Mrp4 (basolateral) transporters were upregulated in abcb11-/- mice. We concluded that infusion of UDCA and TUDC failed to induce bile flow in abcb11-/- mice. UDCA fed to abcb11-/- mice caused liver damage and the appearance of biliary tetra- and penta-hydroxy bile acids. Supplementation with UDCA in the absence of Bsep caused adverse effects in abcb11-/- mice. PMID:23764895

  3. Incorporation of ABCB1-mediated transport into a physiologically-based pharmacokinetic model of docetaxel in mice

    PubMed Central

    Hudachek, Susan F.

    2015-01-01

    Docetaxel is one of the most widely used anticancer agents. While this taxane has proven to be an effective chemotherapeutic drug, noteworthy challenges exist in relation to docetaxel administration due to the considerable interindividual variability in efficacy and toxicity associated with the use of this compound, largely attributable to differences between individuals in their ability to metabolize and eliminate docetaxel. Regarding the latter, the ATP-binding cassette transporter B1 (ABCB1, PGP, MDR1) is primarily responsible for docetaxel elimination. To further understand the role of ABCB1 in the biodistribution of docetaxel in mice, we utilized physiologically-based pharmacokinetic (PBPK) modeling that included ABCB1-mediated transport in relevant tissues. Transporter function was evaluated by studying docetaxel pharmacokinetics in wild-type FVB and Mdr1a/b constitutive knockout (KO) mice and incorporating this concentration–time data into a PBPK model comprised of eight tissue compartments (plasma, brain, heart, lung, kidney, intestine, liver and slowly perfused tissues) and, in addition to ABCB1-mediated transport, included intravenous drug administration, specific binding to intracellular tubulin, intestinal and hepatic metabolism, glomerular filtration and tubular reabsorption. For all tissues in both the FVB and KO cohorts, the PBPK model simulations closely mirrored the observed data. Furthermore, both models predicted AUC values that were with 15 % of the observed AUC values, indicating that our model-simulated drug exposures accurately reflected the observed tissue exposures. Overall, our PBPK model furthers the understanding of the role of ABCB1 in the biodistribution of docetaxel. Additionally, this exemplary model structure can be applied to investigate the pharmacokinetics of other ABCB1 transporter substrates. PMID:23616082

  4. Function and expression of ATP-binding cassette transporters in cultured human Y79 retinoblastoma cells.

    PubMed

    Ishikawa, Yuka; Nagai, Junya; Okada, Yumi; Sato, Koya; Yumoto, Ryoko; Takano, Mikihisa

    2010-01-01

    The aim of this study was to reveal the expression and function of P-glycoprotein and multidrug resistance-associated proteins (MRP), members of the ATP-binding cassette (ABC) superfamily of drug transporters, in cultured human Y79 retinoblastoma cells. ABC transporter mRNA expression was evaluated by conventional reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR analyses. Cellular accumulation of rhodamine 123 (P-glycoprotein substrate), calcein (MRP substrate), and doxorubicin (P-glycoprotein/MRP substrate) was analyzed by fluorometry. Conventional RT-PCR analysis showed the expression of multidrug resistance 1 (MDR1), MRP1, MRP2 and lung resistance-related protein (LRP) mRNAs. Real-time RT-PCR analysis revealed that the expression levels of the MDR1 and MRP2 genes in Y79 cells were much lower than those in human intestinal cell line Caco-2, while the expression level of MRP1 was higher than that in Caco-2 cells. The accumulation of rhodamine 123 was not enhanced by verapamil or reversin 205, inhibitors of P-glycoprotein, indicating no function of P-glycoprotein in Y79 cells. The accumulation of calcein was significantly increased by various MRP inhibitors including probenecid, indicating that MRP functions in Y79 cells. The accumulation of doxorubicin was increased in the presence of metabolic inhibitors (10 mM 2-deoxyglucose and 5 mM sodium azide). However, most MRP inhibitors such as probenecid and indomethacin did not affect doxorubicin accumulation, while cyclosporin A and taclorimus significantly increased doxorubicin accumulation. These results suggest that MRP, but not P-glycoprotein, functions in Y79 cells, and that the efflux of doxorubicin from Y79 cells may be due to an ATP-dependent transporter, which has not been identified yet. PMID:20190417

  5. Influence of acetaminophen vehicle on regulation of transporter gene expression during hepatotoxicity.

    PubMed

    Aleksunes, Lauren M; Augustine, Lisa M; Cherrington, Nathan J; Manautou, José E

    2007-11-01

    Researchers who study acetaminophen (APAP) hepatotoxicity use either a 50% propylene glycol solution or saline as a diluent. Previous studies demonstrated differential expression of hepatobiliary transporter mRNA in mice treated with a toxic dose of APAP dissolved in 50% propylene glycol. The purpose of this study was to determine whether using saline as a diluent for APAP alters regulation of transporter gene expression during hepatotoxicity. Male C57BL/6J mice received acetaminophen (APAP 400 mg/kg, i.p. in saline) or saline (20 ml/kg). Plasma and liver samples were collected at 24 and 48 h for assessment of alanine aminotransferase (ALT) activity and gene expression. It was determined that plasma ALT activity was elevated at 24 and 48 h after APAP administration. Using the branched DNA signal amplification assay, reductions in organic anion-transporting polypeptides Oatp1a1, Oatp1b2, sodium/taurocholate-cotransporting polypeptide (Ntcp), and bile salt export pump (Bsep) mRNA were observed in APAP-treated mice. In contrast, multidrug resistance-associated proteins Mrp1, Mrp2, Mrp3, and Mrp4, as well as multidrug resistance proteins Mdr1a and Mdr1b genes, were increased following APAP. No changes in Oatp1a4, Mdr2, or breast cancer resistance protein (Bcrp) mRNA were observed. Alterations in transporter gene expression in this study were similar to those reported previously using propylene glycol as diluent. With the exceptions of Oatp1a1, Ntcp, and Mrp1, these data mirror previous results suggesting that the solution used to dissolve APAP may alter the susceptibility of mice to hepatotoxicity, but only minimally change the regulation of transporter gene expression.

  6. P-glycoprotein plays a major role in the efflux of fexofenadine in the small intestine and blood-brain barrier, but only a limited role in its biliary excretion.

    PubMed

    Tahara, Harunobu; Kusuhara, Hiroyuki; Fuse, Eiichi; Sugiyama, Yuichi

    2005-07-01

    Fexofenadine is a selective, nonsedating H(1)-receptor antagonist approved for symptoms of allergic conditions, which is mainly excreted into feces via biliary excretion. The purpose of this study is to investigate its pharmacokinetics in mice and rats to determine the role of P-glycoprotein (P-gp) in its biliary excretion. In mice, biliary excretion clearance (17 ml/min/kg) accounted for almost 60% of the total body clearance (30 ml/min/kg). Comparing the pharmacokinetics after intravenous and oral administration indicated that the bioavailability of fexofenadine was at most 2% in mice. Knockout of Mdr1a/1b P-gp did not affect the biliary excretion clearance with regard to both plasma and liver concentrations, whereas the absence of P-gp caused a 6-fold increase in the plasma concentration after oral administration. In addition, the steady-state brain-to-plasma concentration ratio of fexofenadine was approximately 3-fold higher in Mdr1a/1b P-gp knockout mice than in wild-type mice. Together, these results show that P-glycoprotein plays an important role in efflux transport in the brain and small intestine but only a limited role in biliary excretion in mice. In addition, there was no difference in the biliary excretion between normal and hereditarily multidrug resistance-associated protein 2 (Mrp2)-deficient mutant rats (Eisai hyperbilirubinemic rats) and between wild-type and breast cancer resistance protein (Bcrp) knockout mice. These results suggest that the biliary excretion of fexofenadine is mediated by unknown transporters distinct from P-gp, Mrp2, and Bcrp.

  7. PK/PD assessment in CNS drug discovery: Prediction of CSF concentration in rodents for P-glycoprotein substrates and application to in vivo potency estimation.

    PubMed

    Caruso, Antonello; Alvarez-Sánchez, Ruben; Hillebrecht, Alexander; Poirier, Agnès; Schuler, Franz; Lavé, Thierry; Funk, Christoph; Belli, Sara

    2013-06-01

    The unbound drug concentration in brain parenchyma is considered to be the relevant driver for interaction with central nervous system (CNS) biological targets. Drug levels in cerebrospinal fluid (C_CSF) are frequently used surrogates for the unbound concentrations in brain. For drugs actively transported across the blood-brain barrier (BBB), C_CSF differs from unbound plasma concentration (Cu_p) to an extent that is commonly unknown. In this study, the relationship between CSF-to-unbound plasma drug partitioning in rats and the mouse Pgp (Mdr1a) efflux ratio (ER) obtained from in vitro transcellular studies has been investigated for a set of 61 CNS compounds exhibiting substantial diversity in chemical structure and physico-chemical properties. In order to understand the in vitro-in vivo extrapolation of Pgp efflux, a mechanistic model was derived relating in vivo CNS distribution kinetics to in vitro active transport. The model was applied to predict C_CSF from Cu_p and ER data for 19 proprietary Roche CNS drug candidates. The calculated CSF concentrations were correlated with CNS pharmacodynamic responses observed in rodent models. The correlation between in vitro and in vivo potency for different pharmacological endpoints indicated that the predicted C_CSF is a valuable surrogate of the concentration at the target site. Overall, C_CSF proved superior description of PK/PD data than unbound plasma or total brain concentration for Mdr1a substrates. Predicted C_CSF can be used as a default approach to understand the PK/PD relationships in CNS efficacy models and can support the extrapolation of efficacious brain exposure for new drug candidates from rodent to man. PMID:23454189

  8. Thiazide-like diuretic drug metolazone activates human pregnane X receptor to induce cytochrome 3A4 and multidrug-resistance protein 1.

    PubMed

    Banerjee, Monimoy; Chen, Taosheng

    2014-11-15

    Human pregnane X receptor (hPXR) regulates the expression of drug-metabolizing enzyme cytochrome P450 3A4 (CYP3A4) and drug transporters such as multidrug-resistance protein 1 (MDR1). PXR can be modulated by small molecules, including Federal Drug Administration (FDA)-approved drugs, thus altering drug metabolism and causing drug-drug interactions. To determine the role of FDA-approved drugs in PXR-mediated regulation of drug metabolism and clearance, we screened 1481 FDA-approved small-molecule drugs by using a luciferase reporter assay in HEK293T cells and identified the diuretic drug metolazone as an activator of hPXR. Our data showed that metolazone activated hPXR-mediated expression of CYP3A4 and MDR1 in human hepatocytes and intestine cells and increased CYP3A4 promoter activity in various cell lines. Mammalian two-hybrid assays showed that hPXR recruits its co-activator SRC-1 upon metolazone binding in HepG2 cells, explaining the mechanism of hPXR activation. To understand the role of other commonly-used diuretics in hPXR activation and the structure-activity relationship of metolazone, thiazide and non-thiazide diuretics drugs were also tested but only metolazone activates hPXR. To understand the molecular mechanism, docking studies and mutational analysis were carried out and showed that metolazone binds in the ligand-binding pocket and interacts with mostly hydrophobic amino acid residues. This is the first report showing that metolazone activates hPXR. Because activation of hPXR might cause drug-drug interactions, metolazone should be used with caution for drug treatment in patients undergoing combination therapy.

  9. A novel co-culture model of the blood-retinal barrier based on primary retinal endothelial cells, pericytes and astrocytes.

    PubMed

    Wisniewska-Kruk, Joanna; Hoeben, Kees A; Vogels, Ilse M C; Gaillard, Pieter J; Van Noorden, Cornelis J F; Schlingemann, Reinier O; Klaassen, Ingeborg

    2012-03-01

    Loss of blood-retinal barrier (BRB) properties is an important feature in the pathology of diabetic macular edema (DME), but cellular mechanisms underlying BRB dysfunction are poorly understood. Therefore, we developed and characterized a novel in vitro BRB model, based on primary bovine retinal endothelial cells (BRECs). These cells were shown to maintain specific in vivo BRB properties by expressing high levels of the endothelial junction proteins occludin, claudin-5, VE-cadherin and ZO-1 at cell borders, and the specific pumps glucose transporter-1 (GLUT1) and efflux transporter P-glycoprotein (MDR1). To investigate the influence of pericytes and astrocytes on BRB maintenance in vitro, we compared five different co-culture BRB models, based on BRECs, bovine retinal pericytes (BRPCs) and rat glial cells. Co-cultures of BRECs with BRPCs and glial cells showed the highest trans-endothelial resistance (TEER) as well as decreased permeability of tracers after vascular endothelial growth factor (VEGF) stimulation, suggesting a major role for these cell types in maintaining barrier properties. To mimic the in vivo situation of DME, we stimulated BRECs with VEGF, which downregulated MDR1 and GLUT1 mRNA levels, transiently reduced expression levels of endothelial junctional proteins and altered their organization, increased the number of intercellular gaps in BRECs monolayers and influence the permeability of the model to differently-sized molecular tracers. Moreover, as has been shown in vivo, expression of plasmalemma vesicle-associated protein (PLVAP) was increased in endothelial cells in the presence of VEGF. This in vitro model is the first co-culture model of the BRB that mimicks in vivo VEGF-dependent changes occurring in DME. PMID:22200486

  10. High levels of autoantibodies against drug-metabolizing enzymes in SLA/LP-positive AIH-1 sera.

    PubMed

    Shinoda, Masakazu; Tanaka, Yuta; Kuno, Takuya; Matsufuji, Tamiko; Matsufuji, Senya; Murakami, Yasuko; Mizutani, Takaharu

    2004-01-01

    Autoimmune hepatitis type 1 (AIH-1) is characterized by the detection of smooth muscle autoantibodies, antinuclear antibodies and antineutrophil cytoplasmic autoantibodies, and AIH-2 is characterized by the presence of autoantibodies against LKM, which contain drug-metabolizing enzymes. In this study, we measured the levels of drug-metabolizing enzymes in AIH-1 patients (ANA-positive). We exhaustively investigated the level of autoantibodies against major CYPs and UDP-glucuronosyltransferases of typical phase II drug-metabolizing enzymes, a transporter (MDR1), and NADPH-cytochrome P450 reductase in 4 patients with AIH-1 and 6 controls, as a case report. Two (Patients 3 and 4) of the AIH patients exhibited high levels of autoantibodies, while two (Patients 1 and 2) of the patients and the controls did not. The levels of autoantibodies against CYP2C19, CYP2D6, CYP2E1, UGT1A6 and human liver microsomes in Patients 3 and 4 sera were over 2(3) times the levels in Patient 1, Patient 2 and the control sera. Meanwhile, the levels of autoantibodies against CYP1A2, CYP2A6, CYP2C9, UGT2B7, MDR1 and NADPH-cytochrome P450 reductase were 2-2(2) higher in Patients 3 and 4 than in the other subjects. We found that the pattern of elevation in the Patient 3 serum was not parallel with that in Patient 4. Thus, we found high levels of autoantibodies against drug-metabolizing enzymes in AIH-1 patients.

  11. Molecular basis of preferential resistance to colchicine in multidrug-resistant human cells conferred by Gly-185 yields Val-185 substitution in P-glycoprotein

    SciTech Connect

    Safa, A.R.; Stern, R.K.; Choi, Kyunghee; Agresti, M.; Tamai, Ikumi; Mehta, N.D.; Roninson, I.B. )

    1990-09-01

    Expression of P-glycoprotein, encoded by the human MDR1 gene, results in cross-resistance to many lipophilic cytotoxic drugs (multidrug resistance). P-glycoprotein is believed to function as an energy-dependent efflux pump that is responsible for decreased drug accumulation in multidrug-resistant cells. Previous work showed that preferential resistance to colchicine in a colchicine-selected multidrug-resistant cell line was caused by spontaneous mutations in the MDR1 gene that resulted in a Gly-185 {yields} Val-185 substitution in P-glycoprotein. The authors have now compared transfectant cell lines expressing the wild-type Gly-185 or the mutant Val-185 P-glycoprotein with regard to their levels of resistance to and accumulation and binding of different drugs. In cells expressing the mutant protein, increased resistance to colchicine and decreased resistance to vinblastine correlated with a decreased accumulation of colchicine and increased accumulation of vinblastine. Expression of the mutant P-glycoprotein also resulted in significantly increased resistance to epipodophyllotoxin and decreased resistance to vincristine and actinomycin D; smaller changes in resistance were observed for several other drugs. Unexpectedly, the mutant P-glycoprotein showed increased binding of photoactive analogs of vinblastine and verapamil and the photoactive compound azidopine and decreased binding of a photoactive colchicine analog. These results suggest that the Gly-185 {yields} Val-185 substitution affects not the initial drug-binding site of P-glycoprotein but another site, associated with the release of P-glycoprotein-bound drugs to the outside of the cell.

  12. Raltegravir permeability across blood-tissue barriers and the potential role of drug efflux transporters.

    PubMed

    Hoque, M Tozammel; Kis, Olena; De Rosa, María F; Bendayan, Reina

    2015-05-01

    The objectives of this study were to investigate raltegravir transport across several blood-tissue barrier models and the potential interactions with drug efflux transporters. Raltegravir uptake, accumulation, and permeability were evaluated in vitro in (i) P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), multidrug resistance-associated protein 1 (MRP1), or MRP4-overexpressing MDA-MDR1 (P-gp), HEK-ABCG2, HeLa-MRP1, or HEK-MRP4 cells, respectively; (ii) cell culture systems of the human blood-brain (hCMEC/D3), mouse blood-testicular (TM4), and human blood-intestinal (Caco-2) barriers; and (iii) rat jejunum and ileum segments using an in situ single-pass intestinal perfusion model. [(3)H]Raltegravir accumulation by MDA-MDR1 (P-gp) and HEK-ABCG2-overexpressing cells was significantly enhanced in the presence of PSC833 {6-[(2S,4R,6E)-4-methyl-2-(methylamino)-3-oxo-6-octenoic acid]-7-L-valine-cyclosporine}, a P-gp inhibitor, or Ko143 [(3S,6S,12aS)-1,2,3,4,6,7,12,12a-octahydro-9-methoxy-6-(2-methylpropyl)-1,4-dioxopyrazino[1',2':1,6]pyrido[3,4-b]indole-3-propanoic acid 1,1-dimethylethyl ester], a BCRP inhibitor, suggesting the inhibition of a P-gp- or BCRP-mediated efflux process, respectively. Furthermore, [(3)H]raltegravir accumulation by human cerebral microvessel endothelial hCMEC/D3 and mouse Sertoli TM4 cells was significantly increased by PSC833 and Ko143. In human intestinal Caco-2 cells grown on Transwell filters, PSC833, but not Ko143, significantly decreased the [(3)H]raltegravir efflux ratios. In rat intestinal segments, [(3)H]raltegravir in situ permeability was significantly enhanced by the concurrent administration of PSC833 and Ko143. In contrast, in the transporter inhibition assays, raltegravir (10 to 500 μM) did not increase the accumulation of substrate for P-gp (rhodamine-6G), BCRP ([(3)H]mitoxantrone), or MRP1 [2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF)] by MDA-MDR1 (P-gp)-, HEK-ABCG2-, or HeLa-MRP1-overexpressing

  13. Persistence to single-tablet regimen versus less-drug regimen in treatment experienced HIV-infected patients on antiretroviral therapy.

    PubMed

    Jiménez-Galán, Rocio; Cantudo Cuenca, Maria-Rosa; Robustillo-Cortés, María Aguas; Borrego Izquierdo, Y; Almeida-Gonzalez, Carmen Victoria; Morillo-Verdugo, Ramón

    2016-06-01

    Objetivos: Analizar y comparar la persistencia entre las estrategias basadas en Single-Tablet Regimen (STR) y Less Drug Regimen (LDR) en pacientes VIH+. El objetivo secundario del estudio fue determinar factores predictores de persistencia. Material y métodos: Estudio observacional retrospectivo que incluyo los siguientes criterios: pacientes VIH+ con tratamiento antirretroviral (TAR) con un regimen basado en STR o LDR. Se recogieron variables demograficas, factores de riesgo de adquisicion, consumo de drogas, presencia de algun trastorno psiquiatrico y coinfeccion por el virus de la hepatitis B o C. Para comparar la persistencia entre ambas estrategias se realizo un analisis de supervivencia de Kaplan-Meir y se aplico el metodo de log-rank. Se realizo un analisis de regresion de Cox para identificar los factores predictores de persistencia. Resultados: Se incluyeron 244 pacientes, 176 con STR y 68 con LDR. El 34,1% (n = 60) de los pacientes que recibieron un regimen STR abandonaron y en el LDR el 19,1% (n = 13). Los efectos adversos fueron la principal causa de abandono del tratamiento en los pacientes que recibieron STR y el fallo virologico en el regimen LDR. La persistencia de las estrategias STR y LDR fue similar, no encontrandose diferencias estadisticamente significativas entre ambas. El consumo de drogas fue el unico factor predictivo asociado con una menor persistencia (HR = 2,59; p = 0,005). Conclusiones: La persistencia entre los regimenes STR y LDR fue similar, no detectandose diferencias significativas entre ambos. El consumo de drogas fue el unico factor independiente asociado con una menor persistencia del tratamiento antirretroviral.

  14. Evaluation of the Transport, In Vitro Metabolism and Pharmacokinetics of Salvinorin A, a Potent Hallucinogen

    PubMed Central

    Teksin, Zeynep S.; Lee, Insong J.; Nemieboka, Noble N.; Othman, Ahmed A.; Upreti, Vijay V.; Hassan, Hazem E.; Syed, Shariq S.; Prisinzano, Thomas E.; Eddington, Natalie D.

    2009-01-01

    Salvinorin A is an unregulated potent hallucinogen isolated from the leaves of Salvia divinorum. It is the only known non-nitrogenous kappa-opioid selective agonist and rivals synthetic lysergic acid diethylamide (LSD) in potency. This objective of this study was to characterize the in vitro transport, in vitro metabolism, and pharmacokinetic properties of Salvinorin A. The transport characteristics of Salvinorin A were assessed using MDCK-MDR1 cell monolayers. The P-glycoprotein (P-gp) affinity status was assessed by the P-gp ATPase assay. In vitro metabolism studies were performed with various specific human CYP450 isoforms and UGT2B7 to assess the metabolic characteristics of Salvinorin A. Cohorts (n=3) of male Sprague Dawley rats were used to evaluate the pharmacokinetics and brain distribution of Salvinorin A (10 mg/kg, intraperitonal (i.p.) over a 240 min period. A validated UV-HPLC and LC/MS/MS method was used to quantify the hallucinogen concentrations obtained from the in vitro and in vivo studies, respectively. Salvinorin A displayed a high secretory transport in the MDCK-MDR1 cells (4.07±1.34 × 10-5 cm/s). Salvinorin A also stimulated the P-gp ATPase activity in a concentration (5-10 μm) dependent manner, suggesting that it may be a substrate of P-gp. A significant decrease in Salvinorin A concentration ranging from 14.7±0.80 % to 31.1±1.20 % was observed after incubation with CYP2D6, CYP1A1, CYP2C18, and CYP2E1, respectively. A significant decrease was also observed after incubation with UGT2B7. These results suggest that Salvinorin A may be a substrate of UGT2B7, CYP2D6, CYP1A1, CYP2E1 and CYP2C18. The in vivo pharmacokinetic study showed a relatively fast elimination with a half-life (t1/2) of 75 min and a clearance (Cl/F) of 26 L/h/kg. The distribution was extensive (Vd of 47.1 L/kg), however the brain to plasma ratio was 0.050. Accordingly, the brain half life was relatively short, 36 min. Salvinorin A is rapidly eliminated after i.p. dosing

  15. Nanosilver particle effects on drug metabolism in vitro.

    PubMed

    Lamb, John G; Hathaway, Laura B; Munger, Mark A; Raucy, Judy L; Franklin, Michael R

    2010-12-01

    Nanosilver particles are present in consumer and health care products. Their effects on human microsomal cytochrome P450 (P450) activities and induction in luciferase reporter-engineered Caco-2 (MDR1.C) and HepG2 (DPX2 and 1A2DRE) cells have been investigated. The LD(50) values were ∼ 4 μg silver/ml for HepG2 and 5 μg/ml for Caco-2 cells. At silver concentrations that showed no decreased cell viability (<1 μg silver/ml), the pregnane X receptor (PXR)-driven 4.5-fold induction response of MDR1.C cells to 50 μM omeprazole was unaffected. In DPX2 cells, the PXR-driven 5.5- and 6.5-fold induction responses to omeprazole and 10 μM rifampicin were attenuated to 4- and 3.5-fold, respectively. Nanosilver particles alone showed no induction. In 1A2DRE cells, the aryl hydrocarbon receptor-driven 5.5-fold induction response to omeprazole was attenuated to 4-fold. In 1A2DRE cells, nanosilver alone elicited slight induction at 1 μg/ml. The inhibition of human P450-selective activities by nanosilver particles in vitro was proportional to the silver/microsomal protein ratio. At a fixed (0.5 mg/ml) protein concentration, P450-selective activities differed in sensitivity (IC(50) value). Coumarin 7-hydroxylation and 7-ethoxy-4-trifluoromethylcoumarin O-deethylation exhibited the highest IC(50) values (33.5 and 31.9 μM, respectively) and S-mephenytoin 4-hydroxylation exhibited the lowest (6.4 μM). Other IC(50) values were, in ascending order, 8.0 to 9.3 μM (testosterone 6β-hydroxylation, 7-benzyloxyquinoline debenzylation, and diclofenac 4-hydroxylation), 16.0 μM (chlorzoxazone 6-hydroxylation), 21.2 μM [7-methoxy-4-(aminomethyl)-coumarin O-demethylation], and 24.4 μM (7-methoxyresorufin O-demethylation). An investigation of 70 μM nanosilver particles showed that microsomal NADPH cytochrome c reductase activities were inhibited <12%. From our in vitro observations, we extrapolated that nanosilver particles reaching the liver may be a potential source of drug

  16. Drug resistance features and S-phase fraction as possible determinants for drug response in a panel of human ovarian cancer xenografts

    PubMed Central

    Kolfschoten, G M; Hulscher, T M; Pinedo, H M; Boven, E

    2000-01-01

    Multidrug resistance (MDR) and more specifically the expression of P-glycoprotein (Pgp) have been studied extensively in vitro. Unfortunately, it appears that the predictive value of MDR recognized in vitro is mostly an incorrect measure to determine the responsiveness of a particular tumour in the clinic. This misunderstood or overvalued role of MDR might explain the failure of strategies to reverse Pgp function by the use of modulators in solid tumours. To obtain more insight in in vivo drug resistance we investigated a panel of 15 human ovarian cancer xenografts consisting of the most common histological subtypes known in ovarian cancer patients. The response rate to cisplatin, cyclophosphamide and doxorubicin in the xenografts resembled the results of phase II trials with these agents in ovarian cancer patients. This resemblance justifies drug resistance studies in this experimental in vivo human tumour system. We determined the expression levels of MDR 1, MRP 1, LRP and topoisomerase IIα mRNA by the RNase protection assay and the presence of MRP1 and LRP proteins by immunohistochemistry. The S-phase fraction was investigated as a separate parameter by flow cytometry. In none of the 15 ovarian cancer xenografts was MDR 1 expression detectable. The expression levels of MRP 1 and LRP were low to moderate and resembled the presence of the MRP1 and LRP proteins. There was a weak, inverse relationship between the expression levels of LRP and sensitivity to cisplatin and cyclophosphamide (r = –0.44 and –0.45), but not to doxorubicin. The levels of topoisomerase IIα varied among the xenografts (0.73–2.66) and failed to correlate with doxorubicin resistance (r = 0.14). The S-phase fraction, however, showed a relation with the sensitivity to cisplatin (r = 0.66). Among the determinants studied in ovarian cancer in vivo, LRP mRNA and the S-phase fraction were the best predictive factors for drug response and most specifically for the activity of cisplatin.

  17. Feroniellin A-induced autophagy causes apoptosis in multidrug-resistant human A549 lung cancer cells.

    PubMed

    Kaewpiboon, Chutima; Surapinit, Serm; Malilas, Waraporn; Moon, Jeong; Phuwapraisirisan, Preecha; Tip-Pyang, Santi; Johnston, Randal N; Koh, Sang Seok; Assavalapsakul, Wanchai; Chung, Young-Hwa

    2014-04-01

    During the screening of natural chemicals that can reverse multidrug resistance in human A549 lung cancer cells resistant to etoposide (A549RT-eto), we discovered that Feroniellin A (FERO), a novel furanocoumarin, shows toxicity toward A549RT-eto cells in a dose- and time-dependent manner. FERO reduced the expression of NF-κB, leading to downregulation of P-glycoprotein (P-gp), encoded by MDR1, which eventually sensitized A549RT-eto cells to apoptosis. FERO specifically diminished transcription and promoter activity of MDR1 but did not inhibit the expression of other multidrug resistance genes MRP2 and BCRP. Moreover, co-administration of FERO with Bay11-7802, an inhibitor of NF-κB, accelerated apoptosis of A549RT-eto cells through decreased expression of P-gp, indicating that NF-κB is involved in multidrug resistance. Conversely, addition of Z-VAD, a pan-caspase inhibitor, blocked FERO-induced apoptosis in A549RT-eto cells but did not block downregulation of P-gp, indicating that a decrease in P-gp expression is necessary but not sufficient for FERO-induced apoptosis. Interestingly, we found that FERO also induces autophagy, which is characterized by the conversion of LC3 I to LC3 II, induction of GFP-LC3 puncta, enhanced expression of Beclin-1 and ATG5, and inactivation of mTOR. Furthermore, suppression of Beclin-1 by siRNA reduced FERO-induced apoptosis in A549RT-eto cells and activation of autophagy by rapamycin accelerated FERO-induced apoptosis, suggesting that autophagy plays an active role in FERO-induced apoptosis. Herein, we report that FERO reverses multidrug resistance in A549RT-eto cells and exerts its cytotoxic effect by induction of both autophagy and apoptosis, which suggests that FERO can be a useful anticancer drug for multidrug-resistant lung cancer. PMID:24535083

  18. Effects of Methylmercury Contained in a Diet Mimicking the Wayana Amerindians Contamination through Fish Consumption: Mercury Accumulation, Metallothionein Induction, Gene Expression Variations, and Role of the Chemokine CCL2

    PubMed Central

    Bourdineaud, Jean-Paul; Laclau, Muriel; Maury-Brachet, Régine; Gonzalez, Patrice; Baudrimont, Magalie; Mesmer-Dudons, Nathalie; Fujimura, Masatake; Marighetto, Aline; Godefroy, David; Rostène, William; Brèthes, Daniel

    2012-01-01

    Methylmercury (MeHg) is a potent neurotoxin, and human beings are mainly exposed to this pollutant through fish consumption. We addressed the question of whether a diet mimicking the fish consumption of Wayanas Amerindians from French Guiana could result in observable adverse effects in mice. Wayanas adult men are subjected to a mean mercurial dose of 7 g Hg/week/kg of body weight. We decided to supplement a vegetarian-based mice diet with 0.1% of lyophilized Hoplias aimara fish, which Wayanas are fond of and equivalent to the same dose as that afflicting the Wayanas Amerindians. Total mercury contents were 1.4 ± 0.2 and 5.4 ± 0.5 ng Hg/g of food pellets for the control and aimara diets, respectively. After 14 months of exposure, the body parts and tissues displaying the highest mercury concentration on a dry weight (dw) basis were hair (733 ng/g) and kidney (511 ng/g), followed by the liver (77 ng/g). Surprisingly, despite the fact that MeHg is a neurotoxic compound, the brain accumulated low levels of mercury (35 ng/g in the cortex). The metallothionein (MT) protein concentration only increased in those tissues (kidney, muscles) in which MeHg demethylation had occurred. This can be taken as a molecular sign of divalent mercurial contamination since only Hg2+ has been reported yet to induce MT accumulation in contaminated tissues. The suppression of the synthesis of the chemokine CCL2 in the corresponding knockout (KO) mice resulted in important changes in gene expression patterns in the liver and brain. After three months of exposure to an aimara-containing diet, eight of 10 genes selected (Sdhb, Cytb, Cox1, Sod1, Sod2, Mt2, Mdr1a and Bax) were repressed in wild-type mice liver whereas none presented a differential expression in KO Ccl2−/− mice. In the wild-type mice brain, six of 12 genes selected (Cytb, Cox1, Sod1, Sod2, Mdr1a and Bax) presented a stimulated expression, whereas all remained at the basal level of expression in KO Ccl2−/− mice. In the

  19. Adaptive hepatic and intestinal alterations in mice after deletion of NADPH-cytochrome P450 Oxidoreductase (Cpr) in hepatocytes.

    PubMed

    Cheng, Xingguo; Gu, Jun; Klaassen, Curtis D

    2014-11-01

    Cytochrome P450 enzymes (P450) play an important role in first-pass metabolism in both the intestine and liver. NADPH-cytochrome P450 oxidoreductase (Cpr) is an essential electron transfer protein required for microsomal P450 activity. Mice with conditional knockout of Cpr in hepatocytes develop normally and survive even with complete loss of liver microsomal P450 activity. Our current studies were performed to determine whether alternative drug-metabolizing pathways increase in an attempt to maintain whole-body homeostasis. In addition to the liver, Cpr is mainly expressed in tissues such as lung, kidney, and gastrointestinal tract. In livers of H-Cpr-null mice, there is a marked increase in mRNA expression of phase I enzymes (Aldh1a1, 1a7, 3a2; Ces1b2, 2a6, and 2a12), antioxidant enzymes (Ho-1, Nqo1, and epoxide hydrolase), phase II enzymes (Ugt1a9; Gsta1/2, m3, m4, m6, t1, and t3; and Sult1a1 and 1d1), and drug transporters (Oatp1a4, Oct3, Mate1, Mdr1a, and Mrp3 and 4). In addition, glucuronide-conjugated bilirubin concentrations are doubled in serum of H-Cpr-null mice. Both constitutive androstane receptor (CAR) and nuclear factor erythroid 2-related factor 2 (Nrf2) protein in nuclei are higher in the livers of H-Cpr-null mice, indicating that CAR and Nrf2 are activated. In the small intestine of H-Cpr-null mice, mRNA expression of Cyp3a11 and Mdr1a, two genes critical for intestinal first-pass metabolism, are markedly up-regulated. In addition, nutrient (Pept1) and cholesterol (Npc1l1) transporters are induced in the small intestine of H-Cpr-null mice. In conclusion, in H-Cpr-null mice, adaptive regulation of alternative detoxification genes in liver and small intestine appear to partially compensate for the loss of microsomal P450 function in liver.

  20. Cyclosporin A affects the bioavailability of ginkgolic acids via inhibition of P-gp and BCRP.

    PubMed

    Li, Li; Yao, Qing-Qing; Xu, Si-Yun; Hu, Hai-Hong; Shen, Qi; Tian, Ye; Pan, Lan-Ying; Zhou, Hui; Jiang, Hui-di; Lu, Chuang; Yu, Lu-Shan; Zeng, Su

    2014-11-01

    Ginkgolic acids (GAs) in natural product Ginkgobiloba L. are the pharmacological active but also toxic components. Two compounds, GA (C15:1) and GA (C17:1) are the most abundant GAs. In this study, several in vitro and in vivo models were applied to investigate transport mechanism of GAs. A rapid and sensitive LC-MS/MS method for the simultaneous determination of GA (C15:1) and GA (C17:1) was applied to analyze the biological specimens. The Papp(AP→BL) values of GA (C15:1) and GA (C17:1) were 1.66-2.13×10(-)(6)cm/s and 1.34-1.85×10(-)(6)cm/s determined using MDCK and MDCK-MDR1 cell monolayers, respectively. The Papp(BL→AP) were remarkably greater in the MDCK-MDR1 cell line, which were 6.77-11.2×10(-)(6)cm/s for GA (C15:1) and 4.73-5.15×10(-)(6)cm/s for GA (C17:1). Similar results were obtained in LLC-PK1 and LLC-PK1-BCRP cell monolayers. The net efflux ratio of GA (C15:1) and GA (C17:1) in both cell models was greater than 2 and markedly reduced by the presence of Cyclosporin A (CsA) or GF120918, inhibitors of P-gp and BCRP, suggesting that GAs are P-gp and BCRP substrates. The results from a rat bioavailability study also showed that co-administrating CsA intravenously (20mg/kg) could significantly increase GA (C15:1) and GA (C17:1) AUC0-t by 1.46-fold and 1.53-fold and brain concentration levels of 1.43-fold and 1.51-fold, respectively, due to the inhibition of P-gp and BCRP efflux transporters by CsA.

  1. The hypoxia-mimetic agent CoCl₂ induces chemotherapy resistance in LOVO colorectal cancer cells.

    PubMed

    Yang, Guanglei; Xu, Shuqing; Peng, Lintao; Li, Hui; Zhao, Yan; Hu, Yanfang

    2016-03-01

    Hypoxia, which is an important factor that mediates tumor progression and poor treatment response, is particularly associated with tumor chemoresistance. However, the molecular mechanisms underlying hypoxia-induced colorectal cancer chemoresistance remain unclear. The present study aimed to explore the mechanism underlying hypoxia‑induced chemotherapy resistance in LOVO colorectal cancer cells. LOVO cells were cultured in a hypoxic environment simulated by cobalt chloride (CoCl2), which is a chemical inducer of hypoxia‑inducible factor‑1α (HIF‑1α). HIF‑1α is a transcription factor that has an important role in tumor cell adaptation to hypoxia, and controls the expression of several genes. Various CoCl2 concentrations are often used to simulate degrees of hypoxia. In the present study, following treatment with CoCl2, an MTT assay was conducted to determine the growth and drug sensitivity of LOVO cells. Reverse transcription‑polymerase chain reaction and western blotting were used to detect the mRNA and protein expression levels of HIF‑1α and factors associated with chemotherapy resistance, including multidrug resistance protein (MRP) and multidrug resistant 1 (MDR1), which encodes the major transmembrane efflux transporter P‑glycoprotein (P‑gp). In addition, the expression levels of apoptosis‑related proteins, including B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein (Bax) and Bcl‑2‑associated agonist of cell death (Bad) were detected by western blotting. Flow cytometry (FCM) was used to visually observe Adriamycin (ADR) accumulation and retention, thus analyzing intracellular drug transportation in cells under hypoxic and normoxic conditions. CoCl2‑simulated hypoxia was able to inhibit tumor cell proliferation, and upregulate the expression levels of HIF‑1α, MDR1/P‑gp and MRP. In addition, proapoptotic members of the Bcl‑2 protein family, Bax and Bad, were downregulated. The anti‑apoptotic member Bcl‑2

  2. Interaction of HM30181 with P-glycoprotein at the murine blood-brain barrier assessed with positron emission tomography

    PubMed Central

    Bauer, Florian; Wanek, Thomas; Mairinger, Severin; Stanek, Johann; Sauberer, Michael; Kuntner, Claudia; Parveen, Zahida; Chiba, Peter; Müller, Markus; Langer, Oliver; Erker, Thomas

    2013-01-01

    HM30181, a potent and selective inhibitor of the adenosine triphosphate-binding cassette transporter P-glycoprotein (Pgp), was shown to enhance oral bioavailability and improve antitumour efficacy of paclitaxel in mouse tumour models. In search for a positron emission tomography (PET) radiotracer to visualise Pgp expression levels at the blood-brain barrier (BBB), we examined the ability of HM30181 to inhibit Pgp at the murine BBB. HM30181 was shown to be approximately equipotent with the reference Pgp inhibitor tariquidar in inhibiting rhodamine 123 efflux from CCRF-CEM T cells (IC50, tariquidar: 8.2±2.0 nM, HM30181: 13.1±2.3 nM). PET scans with the Pgp substrate (R)-[11C]verapamil in FVB wild-type mice pretreated i.v. with HM30181 (10 or 21 mg/kg) failed to show significant increases in (R)-[11C]verapamil brain uptake compared with vehicle treated animals. PET scans with [11C]HM30181 showed low and not significantly different brain uptake of [11C]HM30181 in wild-type, Mdr1a/b(−/−) and Bcrp1(−/−) mice and significantly, i.e. 4.7-fold (P<0.01), higher brain uptake, relative to wild-type animals, in Mdr1a/b(−/−)Bcrp1(−/−) mice. This was consistent with HM30181 being at microdoses a dual substrate of Pgp and breast cancer resistance protein (Bcrp). In vitro autoradiography on low (EMT6) and high (EMT6Ar1.0) Pgp expressing murine breast tumour sections showed 1.9 times higher binding of [11C]HM30181 in EMT6Ar1.0 tumours (P<0.001) which was displaceable with unlabelled tariquidar, elacridar or HM30181 (1 μM). Our data suggest that HM30181 is not able to inhibit Pgp at the murine BBB at clinically feasible doses and that [11C]HM30181 is not suitable as a PET tracer to visualise cerebral Pgp expression levels. PMID:23022332

  3. JAB1 regulates unphosphorylated STAT3 DNA-binding activity through protein–protein interaction in human colon cancer cells

    SciTech Connect

    Nishimoto, Arata; Kugimiya, Naruji; Hosoyama, Toru; Enoki, Tadahiko; Li, Tao-Sheng; Hamano, Kimikazu

    2013-08-30

    Highlights: •JAB1 interacted with unphosphorylated STAT3 in the nucleus. •JAB1 knockdown tended to increase nuclear STAT3 expression. •JAB1 knockdown significantly decreased unphosphorylated STAT3 DNA-binding activity. •JAB1 knockdown significantly decreased MDR1, NANOG, and VEGF expressions. •Nuclear JAB1, but not nuclear STAT3, correlated with STAT3 DNA-binding activity. -- Abstract: Recent studies have revealed that unphosphorylated STAT3 forms a dimer, translocates to the nucleus, binds to the STAT3 binding site, and activates the transcription of STAT3 target genes, thereby playing an important role in oncogenesis in addition to phosphorylated STAT3. Among signaling steps of unphosphorylated STAT3, nuclear translocation and target DNA-binding are the critical steps for its activation. Therefore, elucidating the regulatory mechanism of these signaling steps of unphosphorylated STAT3 is a potential step in the discovery of a novel cancer drug. However, the mechanism of unphosphorylated STAT3 binding to the promoter of target genes remains unclear. In this study, we focused on Jun activation domain-binding protein 1 (JAB1) as a candidate protein that regulates unphosphorylated STAT3 DNA-binding activity. Initially, we observed that both unphosphorylated STAT3 and JAB1 existed in the nucleus of human colon cancer cell line COLO205 at the basal state (no cytokine stimulation). On the other hand, phosphorylated STAT3 did not exist in the nucleus of COLO205 cells at the basal state. Immunoprecipitation using nuclear extract of COLO205 cells revealed that JAB1 interacted with unphosphorylated STAT3. To investigate the effect of JAB1 on unphosphorylated STAT3 activity, RNAi studies were performed. Although JAB1 knockdown tended to increase nuclear STAT3 expression, it significantly decreased unphosphorylated STAT3 DNA-binding activity. Subsequently, JAB1 knockdown significantly decreased the expression levels of MDR1, NANOG, and VEGF, which are STAT3 target

  4. Feroniellin A-induced autophagy causes apoptosis in multidrug-resistant human A549 lung cancer cells.

    PubMed

    Kaewpiboon, Chutima; Surapinit, Serm; Malilas, Waraporn; Moon, Jeong; Phuwapraisirisan, Preecha; Tip-Pyang, Santi; Johnston, Randal N; Koh, Sang Seok; Assavalapsakul, Wanchai; Chung, Young-Hwa

    2014-04-01

    During the screening of natural chemicals that can reverse multidrug resistance in human A549 lung cancer cells resistant to etoposide (A549RT-eto), we discovered that Feroniellin A (FERO), a novel furanocoumarin, shows toxicity toward A549RT-eto cells in a dose- and time-dependent manner. FERO reduced the expression of NF-κB, leading to downregulation of P-glycoprotein (P-gp), encoded by MDR1, which eventually sensitized A549RT-eto cells to apoptosis. FERO specifically diminished transcription and promoter activity of MDR1 but did not inhibit the expression of other multidrug resistance genes MRP2 and BCRP. Moreover, co-administration of FERO with Bay11-7802, an inhibitor of NF-κB, accelerated apoptosis of A549RT-eto cells through decreased expression of P-gp, indicating that NF-κB is involved in multidrug resistance. Conversely, addition of Z-VAD, a pan-caspase inhibitor, blocked FERO-induced apoptosis in A549RT-eto cells but did not block downregulation of P-gp, indicating that a decrease in P-gp expression is necessary but not sufficient for FERO-induced apoptosis. Interestingly, we found that FERO also induces autophagy, which is characterized by the conversion of LC3 I to LC3 II, induction of GFP-LC3 puncta, enhanced expression of Beclin-1 and ATG5, and inactivation of mTOR. Furthermore, suppression of Beclin-1 by siRNA reduced FERO-induced apoptosis in A549RT-eto cells and activation of autophagy by rapamycin accelerated FERO-induced apoptosis, suggesting that autophagy plays an active role in FERO-induced apoptosis. Herein, we report that FERO reverses multidrug resistance in A549RT-eto cells and exerts its cytotoxic effect by induction of both autophagy and apoptosis, which suggests that FERO can be a useful anticancer drug for multidrug-resistant lung cancer.

  5. Mechanisms limiting distribution of the threonine-protein kinase B-RaF(V600E) inhibitor dabrafenib to the brain: implications for the treatment of melanoma brain metastases.

    PubMed

    Mittapalli, Rajendar K; Vaidhyanathan, Shruthi; Dudek, Arkadiusz Z; Elmquist, William F

    2013-03-01

    Brain metastases are a common cause of death in stage IV metastatic melanoma. Dabrafenib is a BRAF (gene encoding serine/threonine-protein kinase B-Raf) inhibitor that has been developed to selectively target the valine 600 to glutamic acid substitution (BRAF(V600E)), which is commonly found in metastatic melanoma. Clinical trials with dabrafenib have shown encouraging results; however, the central nervous system distribution of dabrafenib remains unknown. Thus, the objective of the current study was to evaluate the brain distribution of dabrafenib in mice, and to see whether active efflux by P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) restricts its delivery across the blood-brain barrier (BBB). In vitro accumulation studies conducted in Madin-Darby canine kidney II cells indicate that dabrafenib is an avid substrate for both P-gp and BCRP. Directional flux studies revealed greater transport in the basolateral to apical direction with corrected efflux ratios greater than 2 for both P-gp and Bcrp1 transfected cell lines. In vivo, the ratio of area under the concentration-time curve (AUC)(brain) to AUC(plasma) (K(p)) of dabrafenib after an i.v. dose (2.5 mg/kg) was 0.023, which increased by 18-fold in Mdr1 a/b(-/-)Bcrp1(-/-) mice to 0.42. Dabrafenib plasma exposure was ∼2-fold greater in Mdr1 a/b(-/-)Bcrp1(-/-) mice as compared with wild-type with an oral dose (25 mg/kg); however, the brain distribution was increased by ~10-fold with a resulting K(p) of 0.25. Further, compared with vemurafenib, another BRAF(V600E) inhibitor, dabrafenib showed greater brain penetration with a similar dose. In conclusion, the dabrafenib brain distribution is limited in an intact BBB model, and the data presented herein may have clinical implications in the prevention and treatment of melanoma brain metastases. PMID:23249624

  6. Impact of P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) on the brain distribution of a novel BRAF inhibitor: vemurafenib (PLX4032).

    PubMed

    Mittapalli, Rajendar K; Vaidhyanathan, Shruthi; Sane, Ramola; Elmquist, William F

    2012-07-01

    Vemurafenib [N-(3-{[5-(4-chlorophenyl)-1H-pyrrolo[2,3-b]pyridin-3-yl]carbonyl}-2,4-difluorophenyl)propane-1-sulfonamide(PLX4032)] is a novel small-molecule BRAF inhibitor, recently approved by the Food and Drug Administration for the treatment of patients with metastatic melanoma with a BRAF(V600E) mutation. The objective of this study was to investigate the role of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) in the distribution of vemurafenib to the central nervous system. In vitro studies conducted in transfected Madin-Darby canine kidney II cells show that the intracellular accumulation of vemurafenib is significantly restricted because of active efflux by P-gp and BCRP. Bidirectional flux studies indicated greater transport in the basolateral-to-apical direction than the apical-to-basolateral direction because of active efflux by P-gp and BCRP. The selective P-gp and BCRP inhibitors zosuquidar and (3S,6S,12aS)-1,2,3,4,6,7,12,12a-octahydro-9-methoxy-6-(2-methylpropyl)-1,4-dioxopyrazino(1',2':1,6)pyrido(3,4-b)indole-3-propanoic acid-1,1-dimethylethyl ester (Ko143) were able to restore the intracellular accumulation and bidirectional net flux of vemurafenib. The in vivo studies revealed that the brain distribution coefficient (area under the concentration time profile of brain/area under the concentration time profile of plasma) of vemurafenib was 0.004 in wild-type mice. The steady-state brain-to-plasma ratio of vemurafenib was 0.035 ± 0.009 in Mdr1a/b(-/-) mice, 0.009 ± 0.006 in Bcrp1(-/-) mice, and 1.00 ± 0.19 in Mdr1a/b(-/-)Bcrp1(-/-) mice compared with 0.012 ± 0.004 in wild-type mice. These data indicate that the brain distribution of vemurafenib is severely restricted at the blood-brain barrier because of active efflux by both P-gp and BCRP. This finding has important clinical significance given the ongoing trials examining the efficacy of vemurafenib in brain metastases of melanoma. PMID:22454535

  7. Effects of methylmercury contained in a diet mimicking the Wayana Amerindians contamination through fish consumption: mercury accumulation, metallothionein induction, gene expression variations, and role of the chemokine CCL2.

    PubMed

    Bourdineaud, Jean-Paul; Laclau, Muriel; Maury-Brachet, Régine; Gonzalez, Patrice; Baudrimont, Magalie; Mesmer-Dudons, Nathalie; Fujimura, Masatake; Marighetto, Aline; Godefroy, David; Rostène, William; Brèthes, Daniel

    2012-01-01

    Methylmercury (MeHg) is a potent neurotoxin, and human beings are mainly exposed to this pollutant through fish consumption. We addressed the question of whether a diet mimicking the fish consumption of Wayanas Amerindians from French Guiana could result in observable adverse effects in mice. Wayanas adult men are subjected to a mean mercurial dose of 7 g Hg/week/kg of body weight. We decided to supplement a vegetarian-based mice diet with 0.1% of lyophilized Hoplias aimara fish, which Wayanas are fond of and equivalent to the same dose as that afflicting the Wayanas Amerindians. Total mercury contents were 1.4 ± 0.2 and 5.4 ± 0.5 ng Hg/g of food pellets for the control and aimara diets, respectively. After 14 months of exposure, the body parts and tissues displaying the highest mercury concentration on a dry weight (dw) basis were hair (733 ng/g) and kidney (511 ng/g), followed by the liver (77 ng/g). Surprisingly, despite the fact that MeHg is a neurotoxic compound, the brain accumulated low levels of mercury (35 ng/g in the cortex). The metallothionein (MT) protein concentration only increased in those tissues (kidney, muscles) in which MeHg demethylation had occurred. This can be taken as a molecular sign of divalent mercurial contamination since only Hg(2+) has been reported yet to induce MT accumulation in contaminated tissues. The suppression of the synthesis of the chemokine CCL2 in the corresponding knockout (KO) mice resulted in important changes in gene expression patterns in the liver and brain. After three months of exposure to an aimara-containing diet, eight of 10 genes selected (Sdhb, Cytb, Cox1, Sod1, Sod2, Mt2, Mdr1a and Bax) were repressed in wild-type mice liver whereas none presented a differential expression in KO Ccl2(-/-) mice. In the wild-type mice brain, six of 12 genes selected (Cytb, Cox1, Sod1, Sod2, Mdr1a and Bax) presented a stimulated expression, whereas all remained at the basal level of expression in KO Ccl2(-/-) mice. In the

  8. Novel understanding of ABC transporters ABCB1/MDR/P-glycoprotein, ABCC2/MRP2, and ABCG2/BCRP in colorectal pathophysiology

    PubMed Central

    Andersen, Vibeke; Svenningsen, Katrine; Knudsen, Lina Almind; Hansen, Axel Kornerup; Holmskov, Uffe; Stensballe, Allan; Vogel, Ulla

    2015-01-01

    AIM: To evaluate ATP-binding cassette (ABC) transporters in colonic pathophysiology as they had recently been related to colorectal cancer (CRC) development. METHODS: Literature search was conducted on PubMed using combinations of the following terms: ABC transporters, ATP binding cassette transporter proteins, inflammatory bowel disease, ulcerative, colitis, Crohns disease, colorectal cancer, colitis, intestinal inflammation, intestinal carcinogenesis, ABCB1/P-glycoprotein (P-gp/CD243/MDR1), ABCC2/multidrug resistance protein 2 (MRP2) and ABCG2/breast cancer resistance protein (BCRP), Abcb1/Mdr1a, abcc2/Mrp2, abcg2/Bcrp, knock-out mice, tight junction, membrane lipid function. RESULTS: Recently, human studies reported that changes in the levels of ABC transporters were early events in the adenoma-carcinoma sequence leading to CRC. A link between ABCB1, high fat diet and gut microbes in relation to colitis was suggested by the animal studies. The finding that colitis was preceded by altered gut bacterial composition suggests that deletion of Abcb1 leads to fundamental changes of host-microbiota interaction. Also, high fat diet increases the frequency and severity of colitis in specific pathogen-free Abcb1 KO mice. The Abcb1 KO mice might thus serve as a model in which diet/environmental factors and microbes may be controlled and investigated in relation to intestinal inflammation. Potential molecular mechanisms include defective transport of inflammatory mediators and/or phospholipid translocation from one side to the other of the cell membrane lipid bilayer by ABC transporters affecting inflammatory response and/or function of tight junctions, phagocytosis and vesicle trafficking. Also, diet and microbes give rise to molecules which are potential substrates for the ABC transporters and which may additionally affect ABC transporter function through nuclear receptors and transcriptional regulation. Another critical role of ABCB1 was suggested by the finding that

  9. Candida albicans AGE3, the Ortholog of the S. cerevisiae ARF-GAP-Encoding Gene GCS1, Is Required for Hyphal Growth and Drug Resistance

    PubMed Central

    Lettner, Thomas; Zeidler, Ute; Gimona, Mario; Hauser, Michael; Breitenbach, Michael; Bito, Arnold

    2010-01-01

    Background Hyphal growth and multidrug resistance of C. albicans are important features for virulence and antifungal therapy of this pathogenic fungus. Methodology/Principal Findings Here we show by phenotypic complementation analysis that the C. albicans gene AGE3 is the functional ortholog of the yeast ARF-GAP-encoding gene GCS1. The finding that the gene is required for efficient endocytosis points to an important functional role of Age3p in endosomal compartments. Most C. albicans age3Δ mutant cells which grew as cell clusters under yeast growth conditions showed defects in filamentation under different hyphal growth conditions and were almost completely disabled for invasive filamentous growth. Under hyphal growth conditions only a fraction of age3Δ cells shows a wild-type-like polarization pattern of the actin cytoskeleton and lipid rafts. Moreover, age3Δ cells were highly susceptible to several unrelated toxic compounds including antifungal azole drugs. Irrespective of the AGE3 genotype, C-terminal fusions of GFP to the drug efflux pumps Cdr1p and Mdr1p were predominantly localized in the plasma membrane. Moreover, the plasma membranes of wild-type and age3Δ mutant cells contained similar amounts of Cdr1p, Cdr2p and Mdr1p. Conclusions/Significance The results indicate that the defect in sustaining filament elongation is probably caused by the failure of age3Δ cells to polarize the actin cytoskeleton and possibly of inefficient endocytosis. The high susceptibility of age3Δ cells to azoles is not caused by inefficient transport of efflux pumps to the cell membrane. A possible role of a vacuolar defect of age3Δ cells in drug susceptibility is proposed and discussed. In conclusion, our study shows that the ARF-GAP Age3p is required for hyphal growth which is an important virulence factor of C. albicans and essential for detoxification of azole drugs which are routinely used for antifungal therapy. Thus, it represents a promising antifungal drug target

  10. P-glycoprotein is responsible for the poor intestinal absorption and low toxicity of oral aconitine: In vitro, in situ, in vivo and in silico studies

    SciTech Connect

    Yang, Cuiping Zhang, Tianhong Li, Zheng Xu, Liang Liu, Fei Ruan, Jinxiu Liu, Keliang Zhang, Zhenqing

    2013-12-15

    Aconitine (AC) is a highly toxic alkaloid from bioactive plants of the genus Aconitum, some of which have been widely used as medicinal herbs for thousands of years. In this study, we systematically evaluated the potential role of P-glycoprotein (P-gp) in the mechanisms underlying the low and variable bioavailability of oral AC. First, the bidirectional transport of AC across Caco-2 and MDCKII-MDR1 cells was investigated. The efflux of AC across monolayers of these two cell lines was greater than its influx. Additionally, the P-gp inhibitors, verapamil and cyclosporin A, significantly decreased the efflux of AC. An in situ intestinal perfusion study in rats showed that verapamil co-perfusion caused a significant increase in the intestinal permeability of AC, from 0.22 × 10{sup −5} to 2.85 × 10{sup −5} cm/s. Then, the pharmacokinetic profile of orally administered AC with or without pre-treatment with verapamil was determined in rats. With pre-treatment of verapamil, the maximum plasma concentration (C{sub max}) of AC increased sharply, from 39.43 to 1490.7 ng/ml. Accordingly, a 6.7-fold increase in the area under the plasma concentration–time curve (AUC{sub 0–12} {sub h}) of AC was observed when co-administered with verapamil. In silico docking analyses suggested that AC and verapamil possess similar P-gp recognition mechanisms. This work demonstrated that P-gp is involved in limiting the intestinal absorption of AC and attenuating its toxicity to humans. Our data indicate that potential P-gp-mediated drug–drug interactions should be considered carefully in the clinical application of aconite and formulations containing AC. - Highlights: • Verapamil and cyclosporin A decreased the efflux of aconitine across Caco-2 cells. • Both inhibitors decreased the efflux of aconitine across MDCKII-MDR1 cells. • Co-perfusion with verapamil increased the intestinal permeability of aconitine. • Co-administration with verapamil sharply increased the C{sub max

  11. Hepatobiliary disposition of 3alpha,6alpha,7alpha,12alpha-tetrahydroxy-cholanoyl taurine: a substrate for multiple canalicular transporters.

    PubMed

    Megaraj, Vandana; Iida, Takashi; Jungsuwadee, Paiboon; Hofmann, Alan F; Vore, Mary

    2010-10-01

    Tetrahydroxy bile acids become major biliary bile acids in Bsep(-/-) mice and Fxr(-/-) mice fed cholic acid; we characterized disposition of these novel bile acids that also occur in patients with cholestasis. We investigated mouse Mrp2 (mMrp2) and P-glycoprotein [(P-gp) mMdr1a]-mediated transport of a tetrahydroxy bile acid, 6α-OH-taurocholic acid (6α-OH-TC), and its biliary excretion in wild-type and Mrp2(-/-) mice in the presence or absence of N-(4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)ethyl]-phenyl)-9,10-dihydro-5-methoxy-9-oxo-4-acridine carboxamide (GF120918), a P-gp and breast cancer resistance protein inhibitor. 6α-OH-TC was rapidly excreted into bile of wild-type mice (78% recovery); coinfusion of GF120918 had no significant effect. In Mrp2(-/-) mice, biliary excretion was decreased (52% recovery) and coinfusion of GF120918 further decreased these values (34% recovery). In wild-type, but not Mrp2(-/-), mice, 6α-OH-TC increased bile flow 2.5-fold. Membrane vesicle transport studies of 6α-OH-TC (0.05-0.75 mM) yielded saturation kinetics with a higher apparent affinity for mMrp2 (K(m) = 0.13 mM) than for mMdr1a (K(m) = 0.33 mM); mBsep transported 6α-OH-TC with positive cooperativity (Hill slope = 2.1). Human multidrug resistance-associated protein (MRP) 2 and P-gp also transported 6α-OH-TC but with positive cooperativity (Hill slope = 3.6 and 1.6, respectively). After intraileal administration, the time course of 6α-OH-TC biliary recovery was similar to that of coinfused taurocholate, implying that 6α-OH-TC can undergo enterohepatic cycling. Thus, Mrp2 plays a key role in 6α-OH-TC biliary excretion, whereas P-glycoprotein plays a secondary role; Bsep likely mediates excretion of 6α-OH-TC in the absence of Mrp2 and P-gp. In Bsep(-/-) mice, efficient synthesis of tetrahydroxy bile acids that are Mrp2 and P-gp substrates can explain the noncholestatic phenotype.

  12. Grape Seed Procyanidin Reversal of P-glycoprotein Associated Multi-Drug Resistance via Down-regulation of NF-κB and MAPK/ERK Mediated YB-1 Activity in A2780/T Cells

    PubMed Central

    Wang, Sheng-qi; Duan, Lian; Huo, Qi-lu; Ren, Fei; Li, Guo-feng

    2013-01-01

    The expression and function of P-glycoprotein (P-gp) is associated with the phenotype of multi-drug resistance (MDR), leading chemotherapy failure of patients suffered with cancer. Grape seed procyanidin(GSP) is a natural polyphenol supplement with anti-inflammatory effect. Present study assessed a new use of GSP on the MDR reversal activity and its possible molecular mechanisms in MDR1-overpressing paclitaxel resistant ovarian cancer cells. Our results showed GSP significantly enhanced the cytotoxicity of paclitaxel and adriamycin in paclitaxel resistant A2780/T cells but its parental A2780 cells. Furthermore, GSP strongly inhibited P-gp expression by blocking MDR1 gene transcription, as well as, increased the intracellular accumulation of the P-gp substrate rhodamine-123 in A2780/T cells. Nuclear factor-κB(NF-κB) activity, IκB degradation level and NF-κB/p65 nuclear translocation induced by lipopolysaccharide (LPS) and receptor activator for nuclear factor-κB ligand (RANKL) were markedly inhibited by pre-treatment with GSP. Meanwhile, GSP inhibited MAPK/ERK pathway by decreasing the phosphorylation of ERK1/2, resulting in reduced the Y-box binding protein 1 (YB-1) activation with blocking its nuclear translocation. Moreover, the up-regulation of P-gp expression, the activation of AKT/NF-κB and MAPK/ERK pathway induced by LPS was attenuated by GSP administration. Compared with PDTC and U1026, inhibitor of NF-κB and MAPK/ERK respectively, GSP showed the same tendency of down-regulating NF-κB and MAPK/ERK mediated YB-1 activities. Thus, GSP reverses P-gp associated MDR by inhibiting the function and expression of P-gp through down-regulation of NF-κB activity and MAPK/ERK pathway mediated YB-1 nuclear translocation, offering insight into the mechanism of reversing MDR by natural polyphenol supplement compounds. GSP could be a new potential MDR reversal agent used for combination therapy with chemotherapeutics in clinic. PMID:23967153

  13. Effects of methylmercury contained in a diet mimicking the Wayana Amerindians contamination through fish consumption: mercury accumulation, metallothionein induction, gene expression variations, and role of the chemokine CCL2.

    PubMed

    Bourdineaud, Jean-Paul; Laclau, Muriel; Maury-Brachet, Régine; Gonzalez, Patrice; Baudrimont, Magalie; Mesmer-Dudons, Nathalie; Fujimura, Masatake; Marighetto, Aline; Godefroy, David; Rostène, William; Brèthes, Daniel

    2012-01-01

    Methylmercury (MeHg) is a potent neurotoxin, and human beings are mainly exposed to this pollutant through fish consumption. We addressed the question of whether a diet mimicking the fish consumption of Wayanas Amerindians from French Guiana could result in observable adverse effects in mice. Wayanas adult men are subjected to a mean mercurial dose of 7 g Hg/week/kg of body weight. We decided to supplement a vegetarian-based mice diet with 0.1% of lyophilized Hoplias aimara fish, which Wayanas are fond of and equivalent to the same dose as that afflicting the Wayanas Amerindians. Total mercury contents were 1.4 ± 0.2 and 5.4 ± 0.5 ng Hg/g of food pellets for the control and aimara diets, respectively. After 14 months of exposure, the body parts and tissues displaying the highest mercury concentration on a dry weight (dw) basis were hair (733 ng/g) and kidney (511 ng/g), followed by the liver (77 ng/g). Surprisingly, despite the fact that MeHg is a neurotoxic compound, the brain accumulated low levels of mercury (35 ng/g in the cortex). The metallothionein (MT) protein concentration only increased in those tissues (kidney, muscles) in which MeHg demethylation had occurred. This can be taken as a molecular sign of divalent mercurial contamination since only Hg(2+) has been reported yet to induce MT accumulation in contaminated tissues. The suppression of the synthesis of the chemokine CCL2 in the corresponding knockout (KO) mice resulted in important changes in gene expression patterns in the liver and brain. After three months of exposure to an aimara-containing diet, eight of 10 genes selected (Sdhb, Cytb, Cox1, Sod1, Sod2, Mt2, Mdr1a and Bax) were repressed in wild-type mice liver whereas none presented a differential expression in KO Ccl2(-/-) mice. In the wild-type mice brain, six of 12 genes selected (Cytb, Cox1, Sod1, Sod2, Mdr1a and Bax) presented a stimulated expression, whereas all remained at the basal level of expression in KO Ccl2(-/-) mice. In the

  14. Life-long diseases need life-long treatment: long-term safety of ciclosporin in canine atopic dermatitis.

    PubMed

    Nuttall, Tim; Reece, Douglas; Roberts, Elizabeth

    2014-03-01

    Ciclosporin (Atopica; Novartis Animal Health) has been licensed for canine atopic dermatitis (AD) since 2002. Adverse events (AEs) have been reported in 55 per cent of 759 dogs in 15 clinical trials, but are rare in pharmacovigilance data (71.81 AEs/million capsules sold). Gastrointestinal reactions were most common, but were mild and rarely required intervention. Other AEs were rare (≤1 per cent in clinical trials; <10/million capsules sold). Hirsutism, gingival hyperplasia and hyperplastic dermatitis were rarely significant and resolved on dose reduction. Ciclosporin decreases staphylococcal and Malassezia infections in AD, and at the recommended dose is not a risk factor for other infections, neoplasia, renal failure or hypertension. The impact on glucose and calcium metabolism is not clinically significant for normal dogs. Concomitant treatment with most drugs is safe. Effects on cytochrome P450 and MDR1 P-glycoprotein activity may elevate plasma ciclosporin concentrations, but short-term changes are not clinically significant. Monitoring of complete blood counts, urinalysis or ciclosporin levels is not justified except with higher than recommended doses and/or long-term concurrent immunosuppressive drugs. Ciclosporin is not a contraindication for killed (including rabies) vaccines, but the licensed recommendation is that live vaccination is avoided during treatment. In conclusion, ciclosporin has a positive risk-benefit profile for the long-term management of canine AD. PMID:24682696

  15. P-glycoprotein-mediated multidrug resistance phenotype of L1210/VCR cells is associated with decreases of oligo- and/or polysaccharide contents.

    PubMed

    Fiala, R; Sulová, Z; El-Saggan, A H; Uhrík, B; Liptaj, T; Dovinová, I; Hanusovská, E; Drobná, Z; Barancík, M; Breier, A

    2003-11-20

    Multidrug resistance of murine leukaemic cell line L1210/VCR (obtained by adaptation of parental drug-sensitive L1210 cells to vincristine) is associated with overexpression of mdr1 gene product P-glycoprotein (Pgp)-the ATP-dependent drug efflux pump. 31P-NMR spectra of L1210 and L1210/VCR cells (the latter in the presence of vincristine) revealed, besides the decrease of ATP level, a considerable lower level of UDP-saccharides in L1210/VCR cells. Histochemical staining of negatively charged cell surface binding sites (mostly sialic acid) by ruthenium red (RR) revealed a compact layer of RR bound to the external coat of sensitive cells. In resistant cells cultivated in the absence or presence of vincristine, the RR layer is either reduced or absent. Consistently, resistant cells were found to be less sensitive to Concanavalin A (ConA). Moreover, differences in the amount and spectrum of glycoproteins interacting with ConA-Sepharose were demonstrated between sensitive and resistant cells. Finally, the content of glycogen in resistant cells is lower than in sensitive cells. All the above facts indicate that multidrug resistance of L1210/VCR cells mediated predominantly by drug efflux activity of Pgp is accompanied by a considerable depression of oligo- and/or polysaccharides biosynthesis.

  16. Bypassing P-Glycoprotein Drug Efflux Mechanisms: Possible Applications in Pharmacoresistant Schizophrenia Therapy

    PubMed Central

    Hoosain, Famida G.; Choonara, Yahya E.; Tomar, Lomas K.; Kumar, Pradeep; Tyagi, Charu; du Toit, Lisa C.; Pillay, Viness

    2015-01-01

    The efficient noninvasive treatment of neurodegenerative disorders is often constrained by reduced permeation of therapeutic agents into the central nervous system (CNS). A vast majority of bioactive agents do not readily permeate into the brain tissue due to the existence of the blood-brain barrier (BBB) and the associated P-glycoprotein efflux transporter. The overexpression of the MDR1 P-glycoprotein has been related to the occurrence of multidrug resistance in CNS diseases. Various research outputs have focused on overcoming the P-glycoprotein drug efflux transporter, which mainly involve its inhibition or bypassing mechanisms. Studies into neurodegenerative disorders have shown that the P-glycoprotein efflux transporter plays a vital role in the progression of schizophrenia, with a noted increase in P-glycoprotein function among schizophrenic patients, thereby reducing therapeutic outcomes. In this review, we address the hypothesis that methods employed in overcoming P-glycoprotein in cancer and other disease states at the level of the BBB and intestine may be applied to schizophrenia drug delivery system design to improve clinical efficiency of drug therapies. In addition, the current review explores polymers and drug delivery systems capable of P-gp inhibition and modulation. PMID:26491671

  17. [Safety of oral ivermectin in children].

    PubMed

    Chosidow, A; Gendrel, D

    2016-02-01

    Ivermectin is an antiparasitic drug, a derivate of avermectins, and a product of fermentation of an actinomycete, Streptomyces avermitilis. Its structure associates two avermectins. Ivermectin acts on the chloride-dependent channels of both glutamate and γ-aminobutyric acid, interrupting neurotransmission in invertebrates. In humans, several mechanisms of brain protection exist, including P-glycoprotein, present on the apical face of endothelial cells of the blood-brain barrier and coded by the MDR1 gene. Ivermectin is presently used in mass treatment of onchocerciasis, other filariasis, some intestinal nematode infections, but also in scabies, and more rarely in resistant head lice. The side effects described are related to the release of antigen and cause an inflammatory reaction. Studies conducted in children or infants have shown good tolerance of ivermectin. However, its use in infants who weigh less than 15kg is a problem because of the absence of marketing authorization for this age group. However, the risk of excessive and uncontrolled use in head lice requires close surveillance. PMID:26697814

  18. The multidrug resistance pumps are inhibited by silibinin and apoptosis induced in K562 and KCL22 leukemia cell lines.

    PubMed

    Noori-Daloii, Mohammad Reza; Saffari, Mojtaba; Raoofian, Reza; Yekaninejad, Mirsaeed; Dinehkabodi, Orkideh Saydi; Noori-Daloii, Ali Reza

    2014-05-01

    Silibinin have been introduced for several years as a potent antioxidant in the field of nutraceuticals. Based on wide persuasive effects of this drug, we have decided to investigate the effects of silibinin on chronic myelogenous leukemia (CML) in vitro models, K562 and KCL22 cell lines. Lactate dehydrogenase (LDH) release, microculture tetrazolium test (MTT assay) and real-time PCR were employed to evaluate the effects of silibinin on cell cytotoxicity, cell proliferation and expression of various multidrug resistance genes in these cell lines, respectively. Our results have shown that presence of silibinin has inhibitory effects on cell proliferation of K562 and KCL22 cell lines. Also, our data indicated that silibinin, in a dose-dependent manner with applying no cytotoxic effects, inhibited cell proliferation and reduced mRNA expression levels of some transporter genes e.g. MDR1, MRP3, MRP2, MRP1, MRP5, MRP4, ABCG2, ABCB11, MRP6 and MRP7. The multifarious in vitro inhibitory effects of silibinin are in agreement with growing body of evidence that silibinin would be an efficient anticancer agent in order to be used in multi-target therapy to prevail the therapeutic hold backs against CML. PMID:24522246

  19. Pharmacogenetics in Ghana: reviewing the evidence.

    PubMed

    Kudzi, W; Adjei, G O; Ofori-Adjei, D; Dodoo, A N O

    2011-06-01

    Different clinical response of different patients to the same medicine has been recognised and documented since the 1950's. Variability in response of individuals to standard doses of drug therapy is important in clinical practice and can lead to therapeutic failures or adverse drug reactions. Pharmacogenetics seeks to identify individual genetic differences (polymorphisms) in drug absorption, metabolism, distribution and excretion that can affect the activity of a particular drug with the view of improving efficacy and reducing toxicity. Although knowledge of pharmacogenetics is being translated into clinical practice in the developed world, its applicability in the developing countries is low. Several factors account for this including the fact that there is very little pharmacogenetic information available in many indigenous African populations including Ghanaians. A number of genes including Cytochrome P450 (CYP) 2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, MDR1 and TPMT have been genotyped in the Ghanaian population since the completion of the Human genome project. There is however, an urgent need to increase pharmacogenetic research in Ghana to increase availability of data. Introducing Pharmacogenetics into the curriculum of Medical and Pharmacy training institutions will influence translating knowledge of pharmacogenetics into clinical practice. This will also equip health professionals with the skill to integrate genetic information into public health decision making. PMID:21857725

  20. Expression of the multidrug transporter P-glycoprotein is inversely related to that of apoptosis-associated endogenous TRAIL

    PubMed Central

    Souza, Paloma S.; Madigan, James P.; Gillet, Jean-Pierre; Kapoor, Khyati; Ambudkar, Suresh V.; Maia, Raquel C.; Gottesman, Michael M.; Fung, King Leung

    2015-01-01

    Multidrug resistance (MDR) has been associated with expression of ABC transporter genes including P-glycoprotein (Pgp, MDR1, ABCB1). However, deregulation of apoptotic pathways also renders cells resistant to chemotherapy. To discover apoptosis-related genes affected by Pgp expression, we used the HeLa MDR-off system. We found that using doxycycline to control Pgp expression has a significant advantage over tetracycline, in that doxycycline caused less endogenous gene expression modification/perturbation, and was more potent than tetracycline in suppressing Pgp expression. Cells overexpressing Pgp have lower TNFSF10 (TRAIL) expression than their parental cells. Controlled downregulation of Pgp increased endogenous TRAIL protein expression. Also, ectopic overexpression of TRAIL in Pgp-positive cells was associated with a reduction in Pgp levels. However, cells expressing a functionally defective mutant Pgp showed an increase in TRAIL expression, suggesting that Pgp function is required for TRAIL suppression. Cells in which Pgp is knocked down by upregulation of TRAIL expression are less susceptible to TRAIL ligand (sTRAIL)-induced apoptosis. Our findings reveal an inverse correlation between functional Pgp and endogenous TRAIL expression. Pgp function plays an important role in the TRAIL-mediated apoptosis pathway by regulating endogenous TRAIL expression and the TRAIL-mediated apoptosis pathway in MDR cancer cells. PMID:26101157

  1. Searching for Multi-Targeting Neurotherapeutics against Alzheimer's: Discovery of Potent AChE-MAO B Inhibitors through the Decoration of the 2H-Chromen-2-one Structural Motif.

    PubMed

    Pisani, Leonardo; Farina, Roberta; Soto-Otero, Ramon; Denora, Nunzio; Mangiatordi, Giuseppe Felice; Nicolotti, Orazio; Mendez-Alvarez, Estefania; Altomare, Cosimo Damiano; Catto, Marco; Carotti, Angelo

    2016-03-17

    The need for developing real disease-modifying drugs against neurodegenerative syndromes, particularly Alzheimer's disease (AD), shifted research towards reliable drug discovery strategies to unveil clinical candidates with higher therapeutic efficacy than single-targeting drugs. By following the multi-target approach, we designed and synthesized a novel class of dual acetylcholinesterase (AChE)-monoamine oxidase B (MAO-B) inhibitors through the decoration of the 2H-chromen-2-one skeleton. Compounds bearing a propargylamine moiety at position 3 displayed the highest in vitro inhibitory activities against MAO-B. Within this series, derivative 3h emerged as the most interesting hit compound, being a moderate AChE inhibitor (IC50 = 8.99 µM) and a potent and selective MAO-B inhibitor (IC50 = 2.8 nM). Preliminary studies in human neuroblastoma SH-SY5Y cell lines demonstrated its low cytotoxicity and disclosed a promising neuroprotective effect at low doses (0.1 µM) under oxidative stress conditions promoted by two mitochondrial toxins (oligomycin-A and rotenone). In a Madin-Darby canine kidney (MDCK)II-MDR1 cell-based transport study, Compound 3h was able to permeate the BBB-mimicking monolayer and did not result in a glycoprotein-p (P-gp) substrate, showing an efflux ratio = 0.96, close to that of diazepam.

  2. Reporter Dyes Demonstrate Functional Expression of Multidrug Resistance Proteins in the Marine Flatworm Macrostomum lignano: The Sponge-Derived Dye Ageladine A Is Not a Substrate of These Transporters

    PubMed Central

    Tietje, Kristin; Rivera-Ingraham, Georgina; Petters, Charlotte; Abele, Doris; Dringen, Ralf; Bickmeyer, Ulf

    2013-01-01

    The marine plathyhelminth Macrostomum lignano was recently isolated from Adriatic shore sediments where it experiences a wide variety of environmental challenges, ranging from hypoxia and reoxygenation, feeding on toxic algae, to exposure to anthropogenic contaminants. As multidrug resistance transporters constitute the first line of defense against toxins and toxicants we have studied the presence of such transporters in M. lignano in living animals by applying optical methods and pharmacological inhibitors that had been developed for mammalian cells. Application of the MDR1 inhibitor Verapamil or of the MRP1 inhibitors MK571 or Probenecid increased the intracellular fluorescence of the reporter dyes Fura-2 am, Calcein am, Fluo-3 am in the worms, but did not affect their staining with the dyes Rhodamine B, CMFDA or Ageladine A. The marine sponge alkaloid Ageladine A remained intracellularly trapped for several days in the worms, suggesting that it does not serve as substrate of multidrug resistance exporters. In addition, Ageladine A did not affect multidrug resistance-associated protein (MRP)-mediated dye export from M. lignano or the MRP1-mediated glutathione (GSH) export from cultured rat brain astrocytes. The data obtained demonstrate that life-imaging is a useful tool to address physiological drug export from intact marine transparent flatworms by using multiphoton scanning microscopy. PMID:24135911

  3. Reporter dyes demonstrate functional expression of multidrug resistance proteins in the marine flatworm Macrostomum lignano: the sponge-derived dye Ageladine A is not a substrate of these transporters.

    PubMed

    Tietje, Kristin; Rivera-Ingraham, Georgina; Petters, Charlotte; Abele, Doris; Dringen, Ralf; Bickmeyer, Ulf

    2013-10-01

    The marine plathyhelminth Macrostomum lignano was recently isolated from Adriatic shore sediments where it experiences a wide variety of environmental challenges, ranging from hypoxia and reoxygenation, feeding on toxic algae, to exposure to anthropogenic contaminants. As multidrug resistance transporters constitute the first line of defense against toxins and toxicants we have studied the presence of such transporters in M. lignano in living animals by applying optical methods and pharmacological inhibitors that had been developed for mammalian cells. Application of the MDR1 inhibitor Verapamil or of the MRP1 inhibitors MK571 or Probenecid increased the intracellular fluorescence of the reporter dyes Fura-2 am, Calcein am, Fluo-3 am in the worms, but did not affect their staining with the dyes Rhodamine B, CMFDA or Ageladine A. The marine sponge alkaloid Ageladine A remained intracellularly trapped for several days in the worms, suggesting that it does not serve as substrate of multidrug resistance exporters. In addition, Ageladine A did not affect multidrug resistance-associated protein (MRP)-mediated dye export from M. lignano or the MRP1-mediated glutathione (GSH) export from cultured rat brain astrocytes. The data obtained demonstrate that life-imaging is a useful tool to address physiological drug export from intact marine transparent flatworms by using multiphoton scanning microscopy. PMID:24135911

  4. Proteasome inhibition reverses hedgehog inhibitor and taxane resistance in ovarian cancer.

    PubMed

    Steg, Adam D; Burke, Mata R; Amm, Hope M; Katre, Ashwini A; Dobbin, Zachary C; Jeong, Dae Hoon; Landen, Charles N

    2014-08-30

    The goal of this study was to determine whether combined targeted therapies, specifically those against the Notch, hedgehog and ubiquitin-proteasome pathways, could overcome ovarian cancer chemoresistance. Chemoresistant ovarian cancer cells were exposed to gamma-secretase inhibitors (GSI-I, Compound E) or the proteasome inhibitor bortezomib, alone and in combination with the hedgehog antagonist, LDE225. Bortezomib, alone and in combination with LDE225, was evaluated for effects on paclitaxel efficacy. Cell viability and cell cycle analysis were assessed by MTT assay and propidium iodide staining, respectively. Proteasome activity and gene expression were determined by luminescence assay and qPCR, respectively. Studies demonstrated that GSI-I, but not Compound E, inhibited proteasome activity, similar to bortezomib. Proteasome inhibition decreased hedgehog target genes (PTCH1, GLI1 and GLI2) and increased LDE225 sensitivity in vitro. Bortezomib, alone and in combination with LDE225, increased paclitaxel sensitivity through apoptosis and G2/M arrest. Expression of the multi-drug resistance gene ABCB1/MDR1 was decreased and acetylation of α-tubulin, a marker of microtubule stabilization, was increased following bortezomib treatment. HDAC6 inhibitor tubastatin-a demonstrated that microtubule effects are associated with hedgehog inhibition and sensitization to paclitaxel and LDE225. These results suggest that proteasome inhibition, through alteration of microtubule dynamics and hedgehog signaling, can reverse taxane-mediated chemoresistance. PMID:25216523

  5. Temozolomide resistance in glioblastoma occurs by miRNA-9-targeted PTCH1, independent of sonic hedgehog level.

    PubMed

    Munoz, Jessian L; Rodriguez-Cruz, Vivian; Ramkissoon, Shakti H; Ligon, Keith L; Greco, Steven J; Rameshwar, Pranela

    2015-01-20

    Glioblastoma Multiforme (GBM), the most common and lethal adult primary tumor of the brain, showed a link between Sonic Hedgehog (SHH) pathway in the resistance to temozolomide (TMZ). PTCH1, the SHH receptor, can tonically represses signaling by endocytosis. We asked how the decrease in PTCH1 in GBM cells could lead to TMZ-resistance. TMZ resistant GBM cells have increased PTCH1 mRNA and reduced protein. Knockdown of Dicer, a Type III RNAase, indicated that miRNAs can explain the decreased PTCH1 in TMZ resistant cells. Computational studies, real-time PCR, reporter gene studies, western blots, target protector oligos and ectopic expression identified miR-9 as the target of PTCH1 in resistant GBM cells with concomitant activation of SHH signaling. MiR-9 mediated increases in the drug efflux transporters, MDR1 and ABCG2. MiR-9 was increased in the tissues from GBM patients and in an early passage GBM cell line from a patient with recurrent GBM but not from a naïve patient. Pharmacological inhibition of SHH signaling sensitized the GBM cells to TMZ. Taken together, miR-9 targets PTCH1 in GBM cells by a SHH-independent method in GBM cells for TMZ resistance. The identified pathways could lead to new strategies to target GBM with combinations of drugs. PMID:25595896

  6. Cell therapy for ischaemic heart disease: focus on the role of resident cardiac stem cells.

    PubMed

    Chamuleau, S A J; Vrijsen, K R; Rokosh, D G; Tang, X L; Piek, J J; Bolli, R

    2009-05-01

    Myocardial infarction results in loss of cardiomyocytes, scar formation, ventricular remodelling, and eventually heart failure. In recent years, cell therapy has emerged as a potential new strategy for patients with ischaemic heart disease. This includes embryonic and bone marrow derived stem cells. Recent clinical studies showed ostensibly conflicting results of intracoronary infusion of autologous bone marrow derived stem cells in patients with acute or chronic myocardial infarction. Anyway, these results have stimulated additional clinical and pre-clinical studies to further enhance the beneficial effects of stem cell therapy. Recently, the existence of cardiac stem cells that reside in the heart itself was demonstrated. Their discovery has sparked intense hope for myocardial regeneration with cells that are obtained from the heart itself and are thereby inherently programmed to reconstitute cardiac tissue. These cells can be detected by several surface markers (e.g. c-kit, Sca-1, MDR1, Isl-1). Both in vitro and in vivo differentiation into cardiomyocytes, endothelial cells and vascular smooth muscle cells has been demonstrated, and animal studies showed promising results on improvement of left ventricular function. This review will discuss current views regarding the feasibility of cardiac repair, and focus on the potential role of the resident cardiac stem and progenitor cells. (Neth Heart J 2009;17:199-207.).

  7. Multidrug resistance protein gene expression in Trichoplusia ni caterpillars.

    PubMed

    Simmons, Jason; D'Souza, Olivia; Rheault, Mark; Donly, Cam

    2013-02-01

    Many insect species exhibit pesticide-resistant phenotypes. One of the mechanisms capable of contributing to resistance is the overexpression of multidrug resistance (MDR) transporter proteins. Here we describe the cloning of three genes encoding MDR proteins from Trichoplusia ni: trnMDR1, trnMDR2 and trnMDR3. Real-time quantitative PCR (qPCR) detected trnMDR mRNA in the whole nervous system, midgut and Malpighian tubules of final instar T. ni caterpillars. To test whether these genes are upregulated in response to chemical challenge in this insect, qPCR was used to compare trnMDR mRNA levels in unchallenged insects with those of insects fed the synthetic pyrethroid, deltamethrin. Only limited increases were detected in a single gene, trnMDR2, which is the most weakly expressed of the three MDR genes, suggesting that increased multidrug resistance of this type is not a significant part of the response to deltamethrin exposure.

  8. Tumor endothelial expression of P-glycoprotein upon microvesicular transfer of TrpC5 derived from adriamycin-resistant breast cancer cells

    SciTech Connect

    Dong, YePing; Pan, QiongXi; Jiang, Li; Chen, Zhen; Zhang, FangFang; Liu, YanJun; Xing, Hui; Shi, Mei; Li, Jiao; Li, XiYuan; Zhu, YaoDan; Chen, Yun; Bruce, Iain C.; Jin, Jian Ma, Xin

    2014-03-28

    Highlights: • TrpC5 was mainly accumulated in microvesicles of drug-resistant MCF-7/ADM cells. • Microvesicles from MCF-7/ADM transferred TrpC5 to endothelial cells. • TrpC5 inhibition reduced P-glycoprotein accumulation on tumor blood vessels in vivo. - Abstract: Treatment of carcinoma commonly fails due to chemoresistance. Studies have shown that endothelial cells acquire resistance via the tumor microenvironment. Microvesicle (MV) shedding from the cell membrane to the microenvironment plays an important role in communication between cells. The aim of the present study was to determine whether MCF-7 adriamycin-resistant cells (MCF-7/ADM) shed MVs that alter the characteristics of human microvessel endothelial cells (HMECs). MVs from tumor cells transferred a Ca{sup 2+}-permeable channel TrpC5 to HMECs, inducing the expression of P-glycoprotein (P-gp) by activation of the transcription factor NFATc3 (nuclear factor of activated T cells isoform c3). Expression of the mdr1 gene was blocked by the TrpC5-blocking antibody T5E3, and the production of P-gp in HMECs was reduced by blockade of TrpC5. Thus, we postulate that endothelial cells acquire the resistant protein upon exposure to TrpC5-containg MVs in the microenvironment, and express P-gp in the TrpC5–NFATc3 signal pathway.

  9. The role of transport processes in survival of lactic acid bacteria. Energy transduction and multidrug resistance.

    PubMed

    Konings, W N; Lolkema, J S; Bolhuis, H; van Veen, H W; Poolman, B; Driessen, A J

    1997-02-01

    Lactic acid bacteria play an essential role in many food fermentation processes. They are anaerobic organisms which obtain their metabolic energy by substrate phosphorylation. In addition three secondary energy transducing processes can contribute to the generation of a proton motive force: proton/substrate symport as in lactic acid excretion, electrogenic precursor/product exchange as in malolactic and citrolactic fermentation and histidine/histamine exchange, and electrogenic uniport as in malate and citrate uptake in Leuconostoc oenos. In several of these processes additional H+ consumption occurs during metabolism leading to the generation of a pH gradient, internally alkaline. Lactic acid bacteria have also developed multidrug resistance systems. In Lactococcus lactis three toxin excretion systems have been characterized: cationic toxins can be excreted by a toxin/proton antiport system and by an ABC-transporter. This cationic ABC-transporter has surprisingly high structural and functional analogy with the human MDR1-(P-glycoprotein). For anions an ATP-driven ABC-like excretion systems exist.

  10. Synergistic Effect of Fluconazole and Calcium Channel Blockers against Resistant Candida albicans

    PubMed Central

    Liu, Shuyuan; Yue, Longtao; Gu, Wenrui; Li, Xiuyun; Zhang, Liuping; Sun, Shujuan

    2016-01-01

    Candidiasis has increased significantly recently that threatens patients with low immunity. However, the number of antifungal drugs on the market is limited in comparison to the number of available antibacterial drugs. This fact, coupled with the increased frequency of fungal resistance, makes it necessary to develop new therapeutic strategies. Combination drug therapy is one of the most widely used and effective strategy to alleviate this problem. In this paper, we were aimed to evaluate the combined antifungal effects of four CCBs (calcium channel blockers), amlodipine (AML), nifedipine (NIF), benidipine (BEN) and flunarizine (FNZ) with fluconazole against C. albicans by checkerboard and time-killing method. In addition, we determined gene (CCH1, MID1, CNA1, CNB1, YVC1, CDR1, CDR2 and MDR1) expression by quantitative PCR and investigated the efflux pump activity of resistant candida albicans by rhodamine 6G assay to reveal the potential mechanisms. Finally, we concluded that there was a synergy when fluconazole combined with the four tested CCBs against resistant strains, with fractional inhibitory concentration index (FICI) <0.5, but no interaction against sensitive strains (FICI = 0.56 ~ 2). The mechanism studies revealed that fluconazole plus amlodipine caused down-regulating of CNA1, CNB1 (encoding calcineurin) and YVC1 (encoding calcium channel protein in vacuole membrane). PMID:26986478

  11. Synergistic Effect of Fluconazole and Calcium Channel Blockers against Resistant Candida albicans.

    PubMed

    Liu, Shuyuan; Yue, Longtao; Gu, Wenrui; Li, Xiuyun; Zhang, Liuping; Sun, Shujuan

    2016-01-01

    Candidiasis has increased significantly recently that threatens patients with low immunity. However, the number of antifungal drugs on the market is limited in comparison to the number of available antibacterial drugs. This fact, coupled with the increased frequency of fungal resistance, makes it necessary to develop new therapeutic strategies. Combination drug therapy is one of the most widely used and effective strategy to alleviate this problem. In this paper, we were aimed to evaluate the combined antifungal effects of four CCBs (calcium channel blockers), amlodipine (AML), nifedipine (NIF), benidipine (BEN) and flunarizine (FNZ) with fluconazole against C. albicans by checkerboard and time-killing method. In addition, we determined gene (CCH1, MID1, CNA1, CNB1, YVC1, CDR1, CDR2 and MDR1) expression by quantitative PCR and investigated the efflux pump activity of resistant candida albicans by rhodamine 6G assay to reveal the potential mechanisms. Finally, we concluded that there was a synergy when fluconazole combined with the four tested CCBs against resistant strains, with fractional inhibitory concentration index (FICI) <0.5, but no interaction against sensitive strains (FICI = 0.56 ~ 2). The mechanism studies revealed that fluconazole plus amlodipine caused down-regulating of CNA1, CNB1 (encoding calcineurin) and YVC1 (encoding calcium channel protein in vacuole membrane).

  12. Laser induced fluorescence as a diagnostic tool integrated into a scanning fiber endoscope for mouse imaging

    NASA Astrophysics Data System (ADS)

    Brown, Christopher M.; Maggio-Price, Lillian; Seibel, Eric J.

    2007-02-01

    Scanning fiber endoscope (SFE) technology has shown promise as a minimally invasive optical imaging tool. To date, it is capable of capturing full-color 500-line images, at 15 Hz frame rate in vivo, as a 1.6 mm diameter endoscope. The SFE uses a singlemode optical fiber actuated at mechanical resonance to scan a light spot over tissue while backscattered or fluorescent light at each pixel is detected in time series using several multimode optical fibers. We are extending the capability of the SFE from a RGB reflectance imaging device to a diagnostic tool by imaging laser induced fluorescence (LIF) in tissue, allowing for correlation of endogenous fluorescence to tissue state. Design of the SFE for diagnostic imaging is guided by a comparison of single point spectra acquired from an inflammatory bowel disease (IBD) model to tissue histology evaluated by a pathologist. LIF spectra were acquired by illuminating tissue with a 405 nm light source and detecting intrinsic fluorescence with a multimode optical fiber. The IBD model used in this study was mdr1a-/- mice, where IBD was modulated by infection with Helicobacter bilis. IBD lesions in the mouse model ranged from mild to marked hyperplasia and dysplasia, from the distal colon to the cecum. A principle components analysis (PCA) was conducted on single point spectra of control and IBD tissue. PCA allowed for differentiation between healthy and dysplastic tissue, indicating that emission wavelengths from 620 - 650 nm were best able to differentiate diseased tissue and inflammation from normal healthy tissue.

  13. MDR-reversal activity of chalcones.

    PubMed

    Ivanova, Antoaneta; Batovska, Daniela; Engi, Helga; Parushev, Stoyan; Ocsovszki, Imre; Kostova, Ivanka; Molnar, Joseph

    2008-01-01

    The ability of 11 chalcones with 3,4,5-trimethoxy substitution on ring A to inhibit the transport activity of P-glycoprotein was studied. Flow cytometry was applied in multidrug-resistant human mdr1 gene-transfected mouse lymphoma cells (L 5178 Y). The reversal of multidrug resistance (MDR) was investigated by measuring the accumulation of rhodamine-123 in cancer cells. Verapamil was applied as a positive control. The majority of the tested compounds were proved to be effective inhibitors of the outward transport of rhodamine-123. In the MTT test, chalcones 2, 3, 5 and 7 exhibited the strongest antiproliferative effects, with 50% inhibitory dose (ID50) =0.19, 0.19, 0.29 and 0.14 microg/mL, respectively. The least effective compounds were 1, 4, 8 and 11, with ID50 values in the range of 1.5-3.5 microg/mL. The antiproliferative effect was shown to be affected by the type of substitution at the p-position on ring B. Chalcone 7, with a p-chloro group on ring B, was the most effective in MDR reversal, causing a marked increase in drug accumulation from 0.4 to 40 microg/mL. In combination with epirubicin, compound 7 displayed synergistic properties while compound 3 exhibited an additive effect. The data presented here indicated that some calcone derivatives can be regarded as effective compounds for reversal of MDR. PMID:18610751

  14. Factors Determining Sensitivity and Resistance of Tumor Cells to Arsenic Trioxide

    PubMed Central

    Sertel, Serkan; Tome, Margaret; Briehl, Margaret M.; Bauer, Judith; Hock, Kai; Plinkert, Peter K.; Efferth, Thomas

    2012-01-01

    Previously, arsenic trioxide showed impressive regression rates of acute promyelocytic leukemia. Here, we investigated molecular determinants of sensitivity and resistance of cell lines of different tumor types towards arsenic trioxide. Arsenic trioxide was the most cytotoxic compound among 8 arsenicals investigated in the NCI cell line panel. We correlated transcriptome-wide microarray-based mRNA expression to the IC50 values for arsenic trioxide by bioinformatic approaches (COMPARE and hierarchical cluster analyses, Ingenuity signaling pathway analysis). Among the identified pathways were signaling routes for p53, integrin-linked kinase, and actin cytoskeleton. Genes from these pathways significantly predicted cellular response to arsenic trioxide. Then, we analyzed whether classical drug resistance factors may also play a role for arsenic trioxide. Cell lines transfected with cDNAs for catalase, thioredoxin, or the anti-apoptotic bcl-2 gene were more resistant to arsenic trioxide than mock vector transfected cells. Multidrug-resistant cells overexpressing the MDR1, MRP1 or BCRP genes were not cross-resistant to arsenic trioxide. Our approach revealed that response of tumor cells towards arsenic trioxide is multi-factorial. PMID:22590507

  15. Evaluating Potential P-gp Substrates: Main Aspects to Choose the Adequate Permeability Model for Assessing Gastrointestinal Drug Absorption.

    PubMed

    da Silva Junior, João Batista; Dezani, Thaisa Marinho; Dezani, André Bersani; dos Reis Serra, Cristina Helena

    2015-01-01

    The success of an oral drug route administration depends on many factors that interfere in its bioavailability, therapeutic efficacy and clinical safety. In human cells, ATP-dependent efflux transporter proteins, such as P-glycoprotein (P-gp), BCRP and MRP2, reduce the absorption of drugs. A tiered approach chosen to evaluate drugs as substrates or inhibitors of efflux pumps, particularly P-gp, should be carefully selected, since each study method has advantages and intrinsic limitations to their processes. Depending on the adopted study conditions, the results may not correspond to the real characteristics of the drug regarding to its modulation by specific efflux proteins. This mini-review aims at summarizing the role of P-gp in the drugs oral absorption and correlating some of the most used permeability methods to determine the drug condition as P-gp substrate. Studies about P-gp have shown that it is a dynamic protein, facilitating secretion of endogenous compounds, as aldosterone, and protecting cells against xenobiotics. Different efflux assays are employed to evaluate drugs as P-gp substrates. In an initial planning, MDCK-MDR1 tend to be the chosen method for efflux studies due its ability of express P-gp, followed by studies conducted in Caco-2 models. However, it is necessary to evaluate the advantages and disadvantages of each method to generate sound results and to set the correlation in vitro x in situ x in vivo. PMID:25963568

  16. Life-long diseases need life-long treatment: long-term safety of ciclosporin in canine atopic dermatitis

    PubMed Central

    Nuttall, Tim; Reece, Douglas; Roberts, Elizabeth

    2014-01-01

    Ciclosporin (Atopica; Novartis Animal Health) has been licensed for canine atopic dermatitis (AD) since 2002. Adverse events (AEs) have been reported in 55 per cent of 759 dogs in 15 clinical trials, but are rare in pharmacovigilance data (71.81 AEs/million capsules sold). Gastrointestinal reactions were most common, but were mild and rarely required intervention. Other AEs were rare (≤1 per cent in clinical trials; <10/million capsules sold). Hirsutism, gingival hyperplasia and hyperplastic dermatitis were rarely significant and resolved on dose reduction. Ciclosporin decreases staphylococcal and Malassezia infections in AD, and at the recommended dose is not a risk factor for other infections, neoplasia, renal failure or hypertension. The impact on glucose and calcium metabolism is not clinically significant for normal dogs. Concomitant treatment with most drugs is safe. Effects on cytochrome P450 and MDR1 P-glycoprotein activity may elevate plasma ciclosporin concentrations, but short-term changes are not clinically significant. Monitoring of complete blood counts, urinalysis or ciclosporin levels is not justified except with higher than recommended doses and/or long-term concurrent immunosuppressive drugs. Ciclosporin is not a contraindication for killed (including rabies) vaccines, but the licensed recommendation is that live vaccination is avoided during treatment. In conclusion, ciclosporin has a positive risk-benefit profile for the long-term management of canine AD. PMID:24682696

  17. Shape profiles and orientation bias for weak and strong lensing cluster halos

    SciTech Connect

    Groener, A. M.; Goldberg, D. M.

    2014-11-10

    We study the intrinsic shape and alignment of isodensities of galaxy cluster halos extracted from the MultiDark MDR1 cosmological simulation. We find that the simulated halos are extremely prolate on small scales and increasingly spherical on larger ones. Due to this trend, analytical projection along the line of sight produces an overestimation of the concentration index as a decreasing function of radius, which we quantify by using both the intrinsic distribution of three-dimensional concentrations (c {sub 200}) and isodensity shape on weak and strong lensing scales. We find this difference to be ∼18% (∼9%) for low- (medium-)mass cluster halos with intrinsically low concentrations (c {sub 200} = 1-3), while we find virtually no difference for halos with intrinsically high concentrations. Isodensities are found to be fairly well aligned throughout the entirety of the radial scale of each halo population. However, major axes of individual halos have been found to deviate by as much as ∼30°. We also present a value-added catalog of our analysis results, which we have made publicly available to download.

  18. RNA interference targeting extracellular matrix metalloproteinase inducer (CD147) inhibits growth and increases chemosensitivity in human cervical cancer cells.

    PubMed

    Zhang, F; Zeng, Y L; Zhang, X G; Chen, W J; Yang, R; Li, S J

    2013-01-01

    Overexpression of extracellular matrix metalloproteinase (MMP) inducer (EMMPRIN CD147) has been implicated in the growth and survival of malignant cells. However, its presence and role in cervical cancer cells has not been well-studied. In the present study, small interfering RNA (siRNA) was designed and synthesized to breakdown the expression of CD147. The present data demonstrated that 24 and 48 hours after transfecting CD147 siRNA, both the CD147 mRNA and protein expression were significantly inhibited as determined by quantitative real-time polymerase chain reaction (RT-PCR) and immunocytochemistry. Meanwhile, simultaneous silencing of CD147 resulted in distinctly increasing MMP-9, VEGF, and MDR-1. Further studies demonstrated decreased CD147 expression, resulted in G1/S phase transition with flow cytometry analysis, as well as the resistance of the cells to 5-FU. These findings provide further evidence that CD147 may become a promising therapeutic target for human cervical cancer and a potential chemotherapy-sensitizing agent.

  19. Design, synthesis, and biological evaluation of a novel series of peripheral-selective noradrenaline reuptake inhibitors-Part 2.

    PubMed

    Yukawa, Tomoya; Fujimori, Ikuo; Kamei, Taku; Nakada, Yoshihisa; Sakauchi, Nobuki; Yamada, Masami; Ohba, Yusuke; Ueno, Hiroyuki; Takiguchi, Maiko; Kuno, Masako; Kamo, Izumi; Nakagawa, Hideyuki; Fujioka, Yasushi; Igari, Tomoko; Ishichi, Yuji; Tsukamoto, Tetsuya

    2016-07-15

    Peripherally selective inhibition of noradrenaline reuptake is a novel mechanism for the treatment of stress urinary incontinence to overcome adverse effects associated with central action. Herein, we describe our medicinal chemistry approach to discover peripheral-selective noradrenaline reuptake inhibitors to avert the risk of P-gp-mediated DDI at the blood-brain barrier. We observed that steric shielding of the hydrogen-bond acceptors and donors (HBA and HBD) of compound 1 reduced the multidrug resistance protein 1 (MDR1) efflux ratio; however, the resulting compound 6, a methoxyacetamide derivative, was mainly metabolized by CYP2D6 and CYP2C19 in the in vitro phenotyping study, implying the risk of PK variability based on the genetic polymorphism of the CYPs. Replacement of the hydrogen atom with a deuterium atom in a strategic, metabolically hot spot led to compound 13, which was mainly metabolized by CYP3A4. To our knowledge, this study represents the first report of the effect of deuterium replacement for a major metabolic enzyme. The compound 13, N-{[(6S,7R)-7-(4-chloro-3-fluorophenyl)-1,4-oxazepan-6-yl]methyl}-2-[(2H(3))methyloxy]acetamide hydrochloride, which exhibited peripheral NET selective inhibition at tested doses in rats, increased urethral resistance in a dose-dependent manner. PMID:27255177

  20. Multidrug resistance-associated ABC transporters - too much of one thing, good for nothing.

    PubMed

    Prochazkova, Jirina; Lanova, Martina; Pachernik, Jiri

    2012-08-01

    Abstract Overexpression of ATP-binding cassette (ABC) transporters in cancer cells results in multidrug resistance (MDR) which leads to unsuccessful chemotherapy. The most important MDR-associated members of ABC superfamily are ABC B1/P-glycoprotein/MDR1, ABC C1/multidrug resistance associated protein 1 (MRP1), and ABC G2/BCRP. This study is not only focused on function, substrates, and localization of these popular proteins but also on other ABC C family members such as ABC C2-6/MRP2-6 and ABC C7/CFTR. Current research is mainly oriented on the cancer-promoting role of these proteins, but important lessons could also be learned from the physiological roles of these proteins or from polymorphisms affecting their function. Thorough knowledge of structure and detailed mechanism of efflux can aid in the discovery of new chemotherapy targets in the future. Although the best way on how to deal with MDR would be to prevent its development, we describe some new promising strategies on how to conquer both inherited and induced MDRs.

  1. Ultrasound-mediated destruction of oxygen and paclitaxel loaded lipid microbubbles for combination therapy in hypoxic ovarian cancer cells.

    PubMed

    Sun, Jiangchuan; Yin, Mingyue; Zhu, Shenyin; Liu, Li; Zhu, Yi; Wang, Zhigang; Xu, Ronald X; Chang, Shufang

    2016-01-01

    We synthesized oxygen and paclitaxel (PTX) loaded lipid microbubbles (OPLMBs) for ultrasound mediated combination therapy in hypoxic ovarian cancer cells. Our experiments successfully demonstrated that ultrasound induced OPLMBs destruction significantly enhanced the local oxygen release. We also demonstrated that OPLMBs in combination with ultrasound (300 kHz, 0.5 W/cm(2), 15s) yielded anti-proliferative activities of 52.8 ± 2.75% and cell apoptosis ratio of 35.25 ± 0.17% in hypoxic cells at 24h after the treatment, superior to other treatment groups such as PTX only and PTX-loaded MBs (PLMBs) with or without ultrasound mediation. RT-PCR and Western blot tests further confirmed the reduced expression of HIF-1α and MDR-1/P-gp after ultrasound mediation of OPLMBs. Our experiment suggests that ultrasound mediation of oxygen and drug-loaded MBs may be a useful method to overcome chemoresistance in the hypoxic ovarian cancer cells.

  2. Antiproliferation of Berberine in Combination with Fluconazole from the Perspectives of Reactive Oxygen Species, Ergosterol and Drug Efflux in a Fluconazole-Resistant Candida tropicalis Isolate

    PubMed Central

    Shao, Jing; Shi, GaoXiang; Wang, TianMing; Wu, DaQiang; Wang, ChangZhong

    2016-01-01

    Candida tropicalis has emerged as an important pathogenic fungus in nosocomial infections due to its recalcitrant resistance to conventional antifungal agents, especially to fluconazole (FLC). Berberine (BBR) is a bioactive herbal-originated alkaloids and has been reported to possess antifungal functions against C. albicans. In this paper, we tried to figure out the antifungal mechanisms of BBR and/or FLC in a clinical C. tropicalis isolate 2006. In the microdilution test, the minimum inhibitory concentration (MIC) of BBR was found 16 μg/mL with fractional inhibitory concentration index (FICI) 0.13 in C. tropicalis 2006. The synergism of BBR and FLC was also confirmed microscopically. After the treatments of BBR and/or FLC, the studies revealed that (i) FLC facilitated BBR to increase reactive oxygen species (ROS), (ii) FLC enhanced the intranuclear accumulation of BBR, (iii) BBR decreased the extracellular rhodamine 123 (Rh123) via inhibiting efflux transporters, (iv) FLC assisted BBR to reduce ergosterol content, and (v) BBR in combined with FLC largely downregulated the expressions of Candida drug resistance 1 (CDR1) and CDR2 but impact slightly multidrug resistance 1 (MDR1), and upregulate the expression of ergosterol 11 (ERG11). These results suggested that BBR could become a potent antifungal drug to strengthen FLC efficacy in FLC-resistant C. tropicalis via ROS increase, intracellular BBR accumulation, ergosterol decrease and efflux inhibition. PMID:27721812

  3. Chemical modification of paclitaxel (Taxol) reduces P-glycoprotein interactions and increases permeation across the blood-brain barrier in vitro and in situ.

    PubMed

    Rice, Antonie; Liu, Yanbin; Michaelis, Mary Lou; Himes, Richard H; Georg, Gunda I; Audus, Kenneth L

    2005-02-10

    The purpose of this work was to introduce a chemical modification into the paclitaxel (Taxol) structure to reduce interactions with the product of the multidrug resistant type 1 (MDR1) gene, P-glycoprotein (Pgp), resulting in improved blood-brain barrier (BBB) permeability. Specifically, a taxane analogue, Tx-67, with a succinate group added at the C10 position of Taxol, was synthesized and identified as such a candidate. In comparison studies, Tx-67 had no apparent interactions with Pgp, as demonstrated by the lack of enhanced uptake of rhodamine 123 by brain microvessel endothelial cells (BMECs) in the presence of the agent. By contrast, Taxol exposure substantially enhanced rhodamine 123 uptake by BMECs through inhibition of Pgp. The transport across BMEC monolayers was polarized for both Tx-67 and Taxol with permeation in the apical to basolateral direction greater for Tx-67 and substantially reduced for Taxol relative to basolateral to apical permeation. Taxol and cyclosporin A treatments also did not enhance Tx-67 permeation across BMEC monolayers. In an in situ rat brain perfusion study, Tx-67 was demonstrated to permeate across the BBB at a greater rate than Taxol. These results demonstrate that the Taxol analogue Tx-67 had a reduced interaction with Pgp and, as a consequence, enhanced permeation across the blood-brain barrier in vitro and in situ.

  4. Socioeconomic Disparities in the Prevalence of Blepharoptosis in the South Korean Adult Population Based on a Nationwide Cross-Sectional Study

    PubMed Central

    Rha, Eun Young; Han, Kyungdo; Park, Yongkyu; Yoo, Gyeol

    2016-01-01

    Purpose We investigated the association between socioeconomic status (SES) and the prevalence of blepharoptosis in a representative South Korean population. Methods This cross-sectional study was based on data obtained in the Korea National Health and Nutrition Examination Survey from 2010 to 2012. In total, 17,178 Korean adults (7,261 men and 9,917 women) aged 19 years or older were enrolled. Blepharoptosis was defined as a marginal reflex distance 1 (MDR 1) lower than 2 mm. Household income and education level were used as indicators of SES. Univariate and multiple logistic regression analyses were conducted to analyze the relationship between SES and the prevalence of blepharoptosis. Results Household income was inversely associated with the prevalence of blepharoptosis in women [adjusted odds ratio (aOR) and corresponding 95% confidence interval (95% CI) was 1.894 (1.336, 2.685)], and educational level was inversely associated with blepharoptosis in both men and women [aORs and 95% CIs were 1.572 (1.113, 2.219) and 1.973 (1.153, 3.376), respectively]. After adjusting for household income and educational level, low SES was associated with a high prevalence of blepharoptosis in women only. Conclusions Socioeconomic disparities in the prevalence of blepharoptosis were found among women. Indeed, future research using a prospective design to determine the causal relationship between SES and blepharoptosis may identify SES as a risk factor for this condition. PMID:26727468

  5. Transepithelial transport of fusariotoxin nivalenol: mediation of secretion by ABC transporters.

    PubMed

    Tep, Jonathan; Videmann, Bernadette; Mazallon, Michèle; Balleydier, Sabine; Cavret, Séverine; Lecoeur, Sylvaine

    2007-05-15

    Mycotoxin nivalenol (NIV) is a natural contaminant of various cereal crops, animal feed and processed grains throughout the world. Human and animal contamination occurs mainly orally, and the toxin must traverse the intestinal epithelial barrier before inducing potential health effects. In this study, we investigated the mechanisms involved in NIV transepithelial transfer. The human intestinal Caco-2 cell line showed a basal-to-apical polarized transport of NIV. Using metabolic inhibitors and temperature-dependent experiments, we demonstrated that basolateral-apical (BL-AP) transfer of NIV involved an energy-dependent transport whereas apical-basolateral (AP-BL) transfer was governed by passive diffusion. NIV efflux was significantly decreased in the presence of the P-glycoprotein (P-gp) inhibitor valspodar, the multi-drug resistance-associated proteins (MRPs) inhibitor MK571, but was not modified by the breast cancer resistance protein (BCRP) inhibitor Ko143. Intracellular NIV accumulation was investigated using epithelial cell lines transfected with either human P-glycoprotein or MRP2. This accumulation was significantly decreased in LLCPK1/MDR1 and MDCKII/MRP2 cells, compared to wild-type cells, and this effect was reversed by valspodar and MK571, respectively. These in vitro results suggested that NIV was a substrate for both P-glycoprotein and MRP2. This interaction may play a key role in weak intestinal absorption of NIV and the mainly predominant excretion of NIV in faeces in animal studies.

  6. Temozolomide down-regulates P-glycoprotein in human blood-brain barrier cells by disrupting Wnt3 signaling.

    PubMed

    Riganti, Chiara; Salaroglio, Iris C; Pinzòn-Daza, Martha L; Caldera, Valentina; Campia, Ivana; Kopecka, Joanna; Mellai, Marta; Annovazzi, Laura; Couraud, Pierre-Olivier; Bosia, Amalia; Ghigo, Dario; Schiffer, Davide

    2014-02-01

    Low delivery of many anticancer drugs across the blood-brain barrier (BBB) is a limitation to the success of chemotherapy in glioblastoma. This is because of the high levels of ATP-binding cassette transporters like P-glycoprotein (Pgp/ABCB1), which effluxes drugs back to the bloodstream. Temozolomide is one of the few agents able to cross the BBB; its effects on BBB cells permeability and Pgp activity are not known. We found that temozolomide, at therapeutic concentration, increased the transport of Pgp substrates across human brain microvascular endothelial cells and decreased the expression of Pgp. By methylating the promoter of Wnt3 gene, temozolomide lowers the endogenous synthesis of Wnt3 in BBB cells, disrupts the Wnt3/glycogen synthase kinase 3/β-catenin signaling, and reduces the binding of β-catenin on the promoter of mdr1 gene, which encodes for Pgp. In co-culture models of BBB cells and human glioblastoma cells, pre-treatment with temozolomide increases the delivery, cytotoxicity, and antiproliferative effects of doxorubicin, vinblastine, and topotecan, three substrates of Pgp that are usually poorly delivered across BBB. Our work suggests that temozolomide increases the BBB permeability of drugs that are normally effluxed by Pgp back to the bloodstream. These findings may pave the way to new combinatorial chemotherapy schemes in glioblastoma.

  7. Prediction of Therapy Response and Prognosis in Leukemias by Flow Cytometric MDR Assays

    PubMed Central

    Hevessy, Zsuzsa; Apjok, András; Jakab, Katalin Tauberné

    2013-01-01

    Multidrug resistance (MDR) is an unwanted phenomenon, that may cause therapy failure in several neoplasms including hematological malignancies. The purpose of any type of laboratory MDR assay is to reliably identify such patients and to provide useful data to clinicians with a relatively short turnaround time. MDR can be multicausal and several previous data identified a group of transmembrane proteins - the ATP-binding casette (ABC) proteins - that may be involved in MDR in various hematological malignancies. The prototype of these proteins is the P-glycoprotein (Pgp, MDR1, ABCB1) that is a seven-membrane spanning transmembrane protein capable of extruding several cytotoxic drugs that are of key importance in the treatment of hematological disorders. Similarly other ABC proteins – Multidrug resistance associated protein 1 (ABCC1) and breast cancer resistance protein (ABCG2) are both capable of pumping out cytotoxic drugs. Here, we present flow cytometric methods to identify MDR proteins by antigen and activity assays. The advantage of flow technology is the short turnaround time and its relative easiness compared to nucleic acid based technologies. However, for the activity assays, it should be noted, that these functional tests require live cells, thus adequate results can only be provided if the specimen transport can be completed within 6 hours of sample collection. Identification of MDR proteins provides prognostic information and may modulate therapy, thus signifies a clinically useful information in the evaluation of patients with leukemias.

  8. Comparison of In vitro Nanoparticles Uptake in Various Cell Lines and In vivo Pulmonary Cellular Transport in Intratracheally Dosed Rat Model

    NASA Astrophysics Data System (ADS)

    Lai, Yurong; Chiang, Po-Chang; Blom, Jason D.; Li, Na; Shevlin, Kimberly; Brayman, Timothy G.; Hu, Yiding; Selbo, Jon G.; Hu, Liangbiao George

    2008-09-01

    In present study, the potential drug delivery of nanoformulations was validated via the comparison of cellular uptake of nanoparticles in various cell lines and in vivo pulmonary cellular uptake in intratracheally (IT) dosed rat model. Nanoparticles were prepared by a bench scale wet milling device and incubated with a series of cell lines, including Caco-2, RAW, MDCK and MDCK transfected MDR1 cells. IT dosed rats were examined for the pulmonary cellular uptake of nanoparticles. The processes of nanoparticle preparation did not alter the crystalline state of the material. The uptake of nanoparticles was observed most extensively in RAW cells and the least in Caco-2 cells. Efflux transporter P-gp did not prevent cell from nanoparticles uptake. The cellular uptake of nanoparticles was also confirmed in bronchoalveolar lavage (BAL) fluid cells and in bronchiolar epithelial cells, type II alveolar epithelial cells in the intratracheally administrated rats. The nanoparticles uptake in MDCK, RAW cells and in vivo lung epithelial cells indicated the potential applications of nanoformulation for poorly soluble compounds. The observed limited direct uptake of nanoparticles in Caco-2 cells suggests that the improvement in oral bioavailability by particle size reduction is via increased dissolution rate rather than direct uptake.

  9. Borneol Depresses P-Glycoprotein Function by a NF-κB Signaling Mediated Mechanism in a Blood Brain Barrier in Vitro Model.

    PubMed

    Fan, Xiang; Chai, Lijuan; Zhang, Han; Wang, Yuefei; Zhang, Boli; Gao, Xiumei

    2015-11-18

    P-glycoprotein (P-gp) on brain microvascular endothelial cells (BMECs) that form the blood brain barrier (BBB), influences transportation of substances between blood and brain. The objective of this study was to characterize the effects of borneol on P-gp efflux function on BBB and explore the potential mechanisms. We established an in vitro BBB model comprised of rat BMECs and astrocytes to measure the effects of borneol on the known P-gp substrates transport across BBB, and examined the function and expression of P-gp in BMECs and the signaling pathways regulating P-gp expression. Borneol increased intracellular accumulation of Rhodamine 123, enhanced verapamil and digoxin across the BBB in vitro model, and depressed mdr1a mRNA and P-gp expression. Borneol could activate nuclear factor-κB (NF-κB) and inhibition of NF-κB with MG132 (carbobenzoxy-Leu-Leu-leucinal) and SN50 (an inhibitory peptide) obscuring the P-gp decreases induced by borneol. These data suggested that borneol depresses P-gp function in BMECs by a NF-κB signaling medicated mechanism in a BBB in vitro model.

  10. The human P-glycoprotein transporter enhances the type I interferon response to Listeria monocytogenes infection.

    PubMed

    Sigal, Nadejda; Kaplan Zeevi, Millie; Weinstein, Shiri; Peer, Dan; Herskovits, Anat A

    2015-06-01

    Human multidrug efflux transporters are known for their ability to extrude antibiotics and toxic compounds out of cells, yet accumulating data indicate they have additional functions in diverse physiological processes not related to drug efflux. Here, we show that the human multidrug transporter P-glycoprotein (P-gp) (also named MDR1 and ABCB1) is transcriptionally induced in the monocytic cell line THP-1 upon infection with the human intracellular bacterial pathogen Listeria monocytogenes. Notably, we found that P-gp is important for full activation of the type I interferon response elicited against L. monocytogenes bacteria. Both inhibition of P-gp function by verapamil and inhibition of its transcription using mRNA silencing led to a reduction in the magnitude of the type I response in infected cells. This function of P-gp was specific to type I interferon cytokines elicited against cytosolic replicating bacteria and was not observed in response to cyclic di-AMP (c-di-AMP), a molecule that was shown to be secreted by L. monocytogenes during infection and to trigger type I interferons. Moreover, P-gp was not involved in activation of other proinflammatory cytokines, such as those triggered by vacuolar-restricted L. monocytogenes or lipopolysaccharide (LPS). Taken together, these findings demonstrate a role for P-gp in proper development of an innate immune response against intracellular pathogens, highlighting the complexity in employing therapeutic strategies that involve inhibition of multidrug resistance (MDR) efflux pumps.

  11. Temozolomide competes for P-glycoprotein and contributes to chemoresistance in glioblastoma cells.

    PubMed

    Munoz, Jessian L; Walker, Nykia D; Scotto, Kathleen W; Rameshwar, Pranela

    2015-10-10

    Chemotherapeutic resistance can occur by P-glycoprotein (P-gp), a 12-transmembrane ATP-dependent drug efflux pump. Glioblastoma (GBM) has poor survival rate and uniformly acquired chemoresistance to its frontline agent, Temozolomide (TMZ). Despite much effort, overcoming TMZ resistance remains a challenge. We reported on autonomous induction of TMZ resistance by increased transcription MDR1, the gene for P-gp. This study investigated how P-gp and TMZ interact to gain resistance. Using an experimental model of Adriamycin-resistant DC3F cells (DC3F/Adx), we showed that increased P-gp caused TMZ resistance. Increasing concentrations of TMZ competed with Calcein for P-gp, resulting in reduced efflux in the DC3F/Adx cells. Three different inhibitors of P-gp reversed the resistance to TMZ in two different GBM cell lines, by increasing active Caspase 3. Molecular modeling predicted the binding sites to be the intracellular region of P-gp and also identified specific amino acids and kinetics of energy for the efflux of TMZ. Taken together, we confirmed P-gp targeting of TMZ, a crucial regulator of TMZ resistance in GBM. This study provides insights on the effectiveness by which TMZ competes with other P-gp substrates, thereby opening the door for combined targeted therapies.

  12. Laurus nobilis L. Seed Extract Reveals Collateral Sensitivity in Multidrug-Resistant P-Glycoprotein-Expressing Tumor Cells.

    PubMed

    Saab, Antoine M; Guerrini, Alessandra; Zeino, Maen; Wiench, Benjamin; Rossi, Damiano; Gambari, Roberto; Sacchetti, Gianni; Greten, Henry Johannes; Efferth, Thomas

    2015-01-01

    The frequent failure of standard cancer chemotherapy requires the development of novel drugs capable of killing otherwise drug-resistant tumors. Here, we have investigated a chloroform extract of Laurus nobilis seeds. Fatty acids and 23 constituents of the volatile fraction were identified by gas chromotography/flame ionization detection (GC/FID) and gas chromatography/mass spectrometry (GC/MS), in good agreement with (1)H NMR (nuclear magnetic resonance) spectrum. Multidrug-resistant P-glycoprotein-expressing CEM/ADR5000 leukemia cells were hypersensitive (collaterally sensitive) toward this extract compared to drug-sensitive CCRF-CEM cells, whereas CEM/ADR5000 cells were 2586-fold resistant to doxorubicin as control drug. Collateral sensitivity was verified by measurement of apoptotic cells by flow cytometry. The log10IC50 values of 3 compounds in the extract (limonene, eucalyptol, oleic acid) did not correlate with mRNA expression of the P-glycoprotein-coding ABCB1/MDR1 gene and accumulation of the P-glycoprotein substrate rhodamine in the NCI panel of tumor cell lines. A microarray-based profile of 20 genes predicted resistance to doxorubicin and 7 other anticancer drugs involved in the multidrug resistance phenotype but not to limonene, eucalyptol and oleic acid. In conclusion, our results show that Laurus nobilis seed extract is suitable to kill multidrug-resistant P-glycoprotein expressing tumor cells.

  13. 1236 C/T and 3435 C/T polymorphisms of the ABCB1 gene in Mexican breast cancer patients.

    PubMed

    Gutierrez-Rubio, S A; Quintero-Ramos, A; Durán-Cárdenas, A; Franco-Topete, R A; Castro-Cervantes, J M; Oceguera-Villanueva, A; Jiménez-Pérez, L M; Balderas-Peña, L M A; Morgan-Villela, G; Del-Toro-Arreola, A; Daneri-Navarro, A

    2015-02-13

    MDR1, which is encoded by the ABCB1 gene, is involved in multidrug resistance (hydrophobic), as well as the elimination of xenotoxic agents. The association between ABCB1 gene polymorphisms and breast cancer risk in different populations has been described previously; however, the results have been inconclusive. In this study, we examined the association between polymorphisms 3435 C/T and 1236 C/T in the ABCB1 gene and breast cancer development in Mexican women according to their menopausal status and molecular classification. Molecular subtypes as well as allele and genotype frequencies were analyzed. A total of 248 women with initial breast cancer diagnosis and 180 ethnically matched, healthy, unrelated individuals were enrolled. Polymerase chain reaction-restriction fragment length polymorphism was performed to detect polymorphisms 3435 C/T and 1236 C/T in the ABCB1 gene. Premenopausal T allele carriers of the 3435 C/T polymorphism showed a 2-fold increased risk of breast cancer with respect to the reference and postmenopausal groups, as well as triple-negative expression regarding the luminal A/B molecular subrogated subtypes. In contrast, the CT genotype of the 1236 polymorphism was a protective factor against breast cancer. We conclude that the T allele carrier of the 3435 C/T polymorphism in the ABCB1 gene in combination with an estrogen receptor-negative status may be an important risk factor for breast cancer development in premenopausal women.

  14. OSI-027 inhibits pancreatic ductal adenocarcinoma cell proliferation and enhances the therapeutic effect of gemcitabine both in vitro and in vivo.

    PubMed

    Zhi, Xiao; Chen, Wei; Xue, Fei; Liang, Chao; Chen, Bryan Wei; Zhou, Yue; Wen, Liang; Hu, Liqiang; Shen, Jian; Bai, Xueli; Liang, Tingbo

    2015-09-22

    Despite its relative rarity, pancreatic ductal adenocarcinoma (PDAC) accounts for a large percentage of cancer deaths. In this study, we investigated the in vitro efficacy of OSI-027, a selective inhibitor of mammalian target of rapamycin complex 1 (mTORC1) and mTORC2, to treat PDAC cell lines alone, and in combination with gemcitabine (GEM). Similarly, we tested the efficacy of these two compounds in a xenograft mouse model of PDAC. OSI-027 significantly arrested cell cycle in G0/G1 phase, inhibited the proliferation of Panc-1, BxPC-3, and CFPAC-1 cells, and downregulated mTORC1, mTORC2, phospho-Akt, phospho-p70S6K, phospho-4E-BP1, cyclin D1, and cyclin-dependent kinase 4 (CDK4) in these cells. Moreover, OSI-027 also downregulated multidrug resistance (MDR)-1, which has been implicated in chemotherapy resistance in PDAC cells and enhanced apoptosis induced by GEM in the three PDAC cell lines. When combined, OSI-027 with GEM showed synergistic cytotoxic effects both in vitro and in vivo. This is the first evidence of the efficacy of OSI-027 in PDAC and may provide the groundwork for a new clinical PDAC therapy. PMID:26213847

  15. Synergistic Effect of Fluconazole and Calcium Channel Blockers against Resistant Candida albicans.

    PubMed

    Liu, Shuyuan; Yue, Longtao; Gu, Wenrui; Li, Xiuyun; Zhang, Liuping; Sun, Shujuan

    2016-01-01

    Candidiasis has increased significantly recently that threatens patients with low immunity. However, the number of antifungal drugs on the market is limited in comparison to the number of available antibacterial drugs. This fact, coupled with the increased frequency of fungal resistance, makes it necessary to develop new therapeutic strategies. Combination drug therapy is one of the most widely used and effective strategy to alleviate this problem. In this paper, we were aimed to evaluate the combined antifungal effects of four CCBs (calcium channel blockers), amlodipine (AML), nifedipine (NIF), benidipine (BEN) and flunarizine (FNZ) with fluconazole against C. albicans by checkerboard and time-killing method. In addition, we determined gene (CCH1, MID1, CNA1, CNB1, YVC1, CDR1, CDR2 and MDR1) expression by quantitative PCR and investigated the efflux pump activity of resistant candida albicans by rhodamine 6G assay to reveal the potential mechanisms. Finally, we concluded that there was a synergy when fluconazole combined with the four tested CCBs against resistant strains, with fractional inhibitory concentration index (FICI) <0.5, but no interaction against sensitive strains (FICI = 0.56 ~ 2). The mechanism studies revealed that fluconazole plus amlodipine caused down-regulating of CNA1, CNB1 (encoding calcineurin) and YVC1 (encoding calcium channel protein in vacuole membrane). PMID:26986478

  16. The Effects and Molecular Mechanisms of MiR-106a in Multidrug Resistance Reversal in Human Glioma U87/DDP and U251/G Cell Lines

    PubMed Central

    Li, Xu; Kan, Pengcheng; Xin, Xin; Zhu, Yu; Yang, Ping

    2015-01-01

    Chemotherapy resistance is one of the major obstacles to effective glioma therapy. Currently, the mechanism underlying chemotherapy resistance is unclear. A recent study showed that miR-106a is an important molecule involved in chemotherapy resistance. To explore the effects and mechanisms of miR-106a on multidrug resistance reversal in human glioma cells, we silenced miR-106a expression in the cisplatin-resistant U87 (U87/DDP) and the gefitinib-resistant U251 (U251/G) glioma cell lines and measured the resulting drug sensitivity, cell apoptosis rate and rhodamine 123 content. In addition, we detected decreased expression of P-glycoprotein, MDR1, MRP1, GST-π, CDX2, ERCC1, RhoE, Bcl-2, Survivin and Topo-II, as well as reduced production of IL-6, IL-8 and TGF-β in these cell lines. Furthermore, we found decreased expression of p-AKT and transcriptional activation of NF-κB, Twist, AP-1 and Snail in these cell lines. These results suggest that miR-106a is a promising therapeutic target for the treatment of human multidrug resistant glioma. PMID:25950430

  17. Human ABCB1 confers cells resistance to cytotoxic guanidine alkaloids from Pterogyne nitens.

    PubMed

    Satake, Kazuhiro; Tsukamoto, Megumi; Mitani, Yuji; Regasini, Luis Octavio; da Silva Bolzani, Vanderlan; Efferth, Thomas; Nakagawa, Hiroshi

    2015-01-01

    Multidrug resistance (MDR) caused by human ABCB1 (P-glycoprotein/MDR1) is one of the major obstacles in chemotherapy. To understand the mechanism of MDR by ABCB1 and circumvent the MDR, in the present study, we established human ABCB1-expressing cells (Flp-In-293/ABCB1 cells) and examined the cytotoxic effects of four guanidine alkaloids from Pterogyne nitens (galegine, nitensidine A, pterogynidine and pterogynine) using Flp-In-293/Mock and Flp-In-293/ABCB1 cells. The activity of ABCB1 in Flp-In-293/ABCB1 cells were confirmed by typical substrates for ABCB1 (taxol and vinblastine) in MTT assay. Flp-In-293/ABCB1 cells were also resistant to the four guanidine alkaloids as well as taxol and vinblastine compared to Flp-In-293/Mock cells although the four guanidine alkaloids exhibited cytotoxicity against the two Flp-In-293 cells. Furthermore, the four guanidine alkaloids were also found to stimulate the ATPase activity of ABCB1 in ATPase assays. These results suggest that ABCB1 can confer the resistance to the cytotoxic guanidine alkaloids by transporting them.

  18. Asclepiasterol, a novel C21 steroidal glycoside derived from Asclepias curassavica, reverses tumor multidrug resistance by down-regulating P-glycoprotein expression.

    PubMed

    Yuan, Wei-Qi; Zhang, Rong-Rong; Wang, Jun; Ma, Yan; Li, Wen-Xue; Jiang, Ren-Wang; Cai, Shao-Hui

    2016-05-24

    Multidrug resistance (MDR) mediated by P-glycoprotein (P-gp) is a major cause of cancer therapy failure. In this study, we identified a novel C21 steroidal glycoside, asclepiasterol, capable of reversing P-gp-mediated MDR. Asclepiasterol (2.5 and 5.0μM) enhanced the cytotoxity of P-gp substrate anticancer drugs in MCF-7/ADR and HepG-2/ADM cells. MDR cells were more responsive to paclitaxel in the presence of asclepiasterol, and colony formation of MDR cells was only reduced upon treatment with a combination of asclepiasterol and doxorubicin. Consistent with these findings, asclepiasterol treatment increased the intracellular accumulation of doxorubicin and rhodamine 123 (Rh123) in MDR cells. Asclepiasterol decreased expression of P-gp protein without stimulating or suppressing MDR1 mRNA levels. Asclepiasterol-mediated P-gp suppression caused inhibition of ERK1/2 phosphorylation in two MDR cell types, and EGF, an activator of the MAPK/ERK pathway, reversed the P-gp down-regulation, implicating the MAPK/ERK pathway in asclepiasterol-mediated P-gp down-regulation. These results suggest that asclepiasterol could be developed as a modulator for reversing P-gp-mediated MDR in P-gp-overexpressing cancer variants.

  19. Targeting ABCB1-mediated tumor multidrug resistance by CRISPR/Cas9-based genome editing

    PubMed Central

    Yang, Yang; Qiu, Jian-Ge; Li, Yong; Di, Jin-Ming; Zhang, Wen-Ji; Jiang, Qi-Wei; Zheng, Di-Wei; Chen, Yao; Wei, Meng-Ning; Huang, Jia-Rong; Wang, Kun; Shi, Zhi

    2016-01-01

    The RNA-guided clustered regularly interspaced short palindromic (CRISPR) in combination with a CRISPR-associated nuclease 9 (Cas9) nuclease system is a new rapid and precise technology for genome editing. In the present study, we applied the CRISPR/Cas9 system to target ABCB1 (also named MDR1) gene which encodes a 170 kDa transmembrane glycoprotein (P-glycoprotein/P-gp) transporting multiple types of chemotherapeutic drugs including taxanes, epipodophyllotoxins, vinca alkaloids and anthracyclines out of cells to contribute multidrug resistance (MDR) in cancer cells. Our data showed that knockout of ABCB1 by CRISPR/Cas9 system was succesfully archieved with two target sgRNAs in two MDR cancer cells due to the alteration of genome sequences. Knockout of ABCB1 by CRISPR/Cas9 system significantly enhances the sensitivity of ABCB1 substrate chemotherapeutic agents and the intracellular accumulation of rhodamine 123 and doxorubicin in MDR cancer cells. Although now there are lots of limitations to the application of CRISPR/Cas9 for editing cancer genes in human patients, our study provides valuable clues for the use of the CRISPR/Cas9 technology in the investigation and conquest of cancer MDR. PMID:27725879

  20. Drug Efflux Transporters Are Overexpressed in Short-Term Tamoxifen-Induced MCF7 Breast Cancer Cells.

    PubMed

    Krisnamurti, Desak Gede Budi; Louisa, Melva; Anggraeni, Erlia; Wanandi, Septelia Inawati

    2016-01-01

    Tamoxifen is the first line drug used in the treatment of estrogen receptor-positive (ER+) breast cancer. The development of multidrug resistance (MDR) to tamoxifen remains a major challenge in the treatment of cancer. One of the mechanisms related to MDR is decrease of drug influx via overexpression of drug efflux transporters such as P-glycoprotein (P-gp/MDR1), multidrug resistance associated protein (MRP), or BCRP (breast cancer resistance protein). We aimed to investigate whether the sensitivity of tamoxifen to the cells is maintained through the short period and whether the expressions of several drug efflux transporters have been upregulated. We exposed MCF7 breast cancer cells with tamoxifen 1 μM for 10 passages (MCF7 (T)). The result showed that MCF7 began to lose their sensitivity to tamoxifen from the second passage. MCF7 (T) also showed a significant increase in all transporters examined compared with MCF7 parent cells. The result also showed a significant increase of CC50 in MCF7 (T) compared to that in MCF7 (97.54 μM and 3.04 μM, resp.). In conclusion, we suggest that the expression of several drug efflux transporters such as P-glycoprotein, MRP2, and BCRP might be used and further studied as a marker in the development of tamoxifen resistance. PMID:26981116

  1. Development of a Support Vector Machine-Based System to Predict Whether a Compound Is a Substrate of a Given Drug Transporter Using Its Chemical Structure.

    PubMed

    Ose, Atsushi; Toshimoto, Kota; Ikeda, Kazushi; Maeda, Kazuya; Yoshida, Shuya; Yamashita, Fumiyoshi; Hashida, Mitsuru; Ishida, Takashi; Akiyama, Yutaka; Sugiyama, Yuichi

    2016-07-01

    The aim of this study was to develop an in silico prediction system to assess which of 7 categories of drug transporters (organic anion transporting polypeptide [OATP] 1B1/1B3, multidrug resistance-associated protein [MRP] 2/3/4, organic anion transporter [OAT] 1, OAT3, organic cation transporter [OCT] 1/2/multidrug and toxin extrusion [MATE] 1/2-K, multidrug resistance protein 1 [MDR1], and breast cancer resistance protein [BCRP]) can recognize compounds as substrates using its chemical structure alone. We compiled an internal data set consisting of 260 compounds that are substrates for at least 1 of the 7 categories of drug transporters. Four physicochemical parameters (charge, molecular weight, lipophilicity, and plasma unbound fraction) of each compound were used as the basic descriptors. Furthermore, a greedy algorithm was used to select 3 additional physicochemical descriptors from 731 available descriptors. In addition, transporter nonsubstrates tend not to be in the public domain; we, thus, tried to compile an expert-curated data set of putative nonsubstrates for each transporter using personal opinions of 11 researchers in the field of drug transporters. The best prediction was finally achieved by a support vector machine based on 4 basic and 3 additional descriptors. The model correctly judged that 364 of 412 compounds (internal data set) and 111 of 136 compounds (external data set) were substrates, indicating that this model performs well enough to predict the specificity of transporter substrates. PMID:27262201

  2. Redox Control of Multidrug Resistance and Its Possible Modulation by Antioxidants

    PubMed Central

    Cort, Aysegul; Ozben, Tomris; Saso, Luciano; De Luca, Chiara

    2016-01-01

    Clinical efficacy of anticancer chemotherapies is dramatically hampered by multidrug resistance (MDR) dependent on inherited traits, acquired defence against toxins, and adaptive mechanisms mounting in tumours. There is overwhelming evidence that molecular events leading to MDR are regulated by redox mechanisms. For example, chemotherapeutics which overrun the first obstacle of redox-regulated cellular uptake channels (MDR1, MDR2, and MDR3) induce a concerted action of phase I/II metabolic enzymes with a temporal redox-regulated axis. This results in rapid metabolic transformation and elimination of a toxin. This metabolic axis is tightly interconnected with the inducible Nrf2-linked pathway, a key switch-on mechanism for upregulation of endogenous antioxidant enzymes and detoxifying systems. As a result, chemotherapeutics and cytotoxic by-products of their metabolism (ROS, hydroperoxides, and aldehydes) are inactivated and MDR occurs. On the other hand, tumour cells are capable of mounting an adaptive antioxidant response against ROS produced by chemotherapeutics and host immune cells. The multiple redox-dependent mechanisms involved in MDR prompted suggesting redox-active drugs (antioxidants and prooxidants) or inhibitors of inducible antioxidant defence as a novel approach to diminish MDR. Pitfalls and progress in this direction are discussed. PMID:26881027

  3. Change of drug excretory pathway by CCl4-induced liver dysfunction in rat.

    PubMed

    Okumura, Hirotoshi; Katoh, Miki; Minami, Keiichi; Nakajima, Miki; Yokoi, Tsuyoshi

    2007-08-01

    Liver dysfunction affects the pharmacokinetics of drugs. The liver plays an important role in drug excretion as well as drug metabolism and pharmacokinetics. In the present study, the relationship between changes in the cefmetazole (CMZ) excretory pathway and the degree of liver dysfunction induced by CCl(4) treatment was investigated. CMZ is mainly excreted as an unchanged form in feces in control rats. Depending on the serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), urinary CMZ excretion was increased, whereas fecal CMZ excretion was decreased in rat with liver dysfunction. The AUC of CMZ in rats with severe liver dysfunction was approximately 2-fold higher than that in control rats. Since drug transporters could be involved in drug excretion, changes in the expression of representative hepatic drug transporters in liver dysfunction were investigated by rat DNA microarray. Basolateral solute carrier transporters such as Ntcp, Oct1, and Oatp2 were decreased and basolateral ATP-binding cassette transporters such as Mrp3 and Mrp4 were increased by the CCl(4) treatment. On the other hand, canalicular Mrp2 and Bsep were decreased, but Mdr1 was increased. However, the transporter system for CMZ has not been identified yet. In conclusion, we clarified that the fecal and urinary excretory profiles of CMZ were changed clearly depending on the serum AST and ALT levels in liver dysfunction. The changes in the CMZ excretory pathway might be responsible for the changes in the expression of drug transporters.

  4. Development, Maintenance, and Reversal of Multiple Drug Resistance: At the Crossroads of TFPI1, ABC Transporters, and HIF1α

    PubMed Central

    Arnason, Terra; Harkness, Troy

    2015-01-01

    Early detection and improved therapies for many cancers are enhancing survival rates. Although many cytotoxic therapies are approved for aggressive or metastatic cancer; response rates are low and acquisition of de novo resistance is virtually universal. For decades; chemotherapeutic treatments for cancer have included anthracyclines such as Doxorubicin (DOX); and its use in aggressive tumors appears to remain a viable option; but drug resistance arises against DOX; as for all other classes of compounds. Our recent work suggests the anticoagulant protein Tissue Factor Pathway Inhibitor 1α (TFPI1α) plays a role in driving the development of multiple drug resistance (MDR); but not maintenance; of the MDR state. Other factors; such as the ABC transporter drug efflux pumps MDR-1/P-gp (ABCB1) and BCRP (ABCG2); are required for MDR maintenance; as well as development. The patient population struggling with therapeutic resistance specifically requires novel treatment options to resensitize these tumor cells to therapy. In this review we discuss the development, maintenance, and reversal of MDR as three distinct phases of cancer biology. Possible means to exploit these stages to reverse MDR will be explored. Early molecular detection of MDR cancers before clinical failure has the potential to offer new approaches to fighting MDR cancer. PMID:26501324

  5. Doxorubicin-resistant LoVo adenocarcinoma cells display resistance to apoptosis induction by some but not all inhibitors of ser/thr phosphatases 1 and 2A.

    PubMed

    Sieder, S; Richter, E; Becker, K; Heins, R; Steinfelder, H J

    1999-06-15

    LoVo adenocarcinoma cells are fairly sensitive to cytostatic drugs, e.g. doxorubicin, but can develop drug resistance by expression of a P-glycoprotein-mediated MDR1 phenotype. LoVo cells respond with apoptosis to nanomolar concentrations of okadaic acid and micromolar concentrations of cantharidic acid. Interestingly, LoVoDx cells which had become about 10-fold less sensitive to doxorubicin by incubation in increasing concentrations of this cytostatic drug were also less sensitive to the toxicity of okadaic acid. Resistance to both agents was lost or significantly reduced by incubation in drug-free medium for about 4 months. On the other hand, LoVoDx cells did not lose responsiveness to the structurally different phosphatase inhibitor cantharidic acid but were about twofold more sensitive to the cytotoxic effect of this agent. Thus, MDR expression protects LoVo cells from the toxicity of phosphatase inhibitors that presumably are substrates of the P-glycoprotein, e.g. okadaic acid and its derivatives but not cantharidic acid, despite the fact that both agents are potent inducers of apoptotic cell death via ser/thr phosphatase inhibition.

  6. Borneol Depresses P-Glycoprotein Function by a NF-κB Signaling Mediated Mechanism in a Blood Brain Barrier in Vitro Model

    PubMed Central

    Fan, Xiang; Chai, Lijuan; Zhang, Han; Wang, Yuefei; Zhang, Boli; Gao, Xiumei

    2015-01-01

    P-glycoprotein (P-gp) on brain microvascular endothelial cells (BMECs) that form the blood brain barrier (BBB), influences transportation of substances between blood and brain. The objective of this study was to characterize the effects of borneol on P-gp efflux function on BBB and explore the potential mechanisms. We established an in vitro BBB model comprised of rat BMECs and astrocytes to measure the effects of borneol on the known P-gp substrates transport across BBB, and examined the function and expression of P-gp in BMECs and the signaling pathways regulating P-gp expression. Borneol increased intracellular accumulation of Rhodamine 123, enhanced verapamil and digoxin across the BBB in vitro model, and depressed mdr1a mRNA and P-gp expression. Borneol could activate nuclear factor-κB (NF-κB) and inhibition of NF-κB with MG132 (carbobenzoxy-Leu-Leu-leucinal) and SN50 (an inhibitory peptide) obscuring the P-gp decreases induced by borneol. These data suggested that borneol depresses P-gp function in BMECs by a NF-κB signaling medicated mechanism in a BBB in vitro model. PMID:26593909

  7. Combination of amikacin and doxycycline against multidrug-resistant and extensively drug-resistant tuberculosis.

    PubMed

    Gonzalo, Ximena; Casali, Nicola; Broda, Agnieszka; Pardieu, Claire; Drobniewski, Francis

    2015-04-01

    The objective of this study was to assess the activity of amikacin in combination with doxycycline against clinical strains of Mycobacterium tuberculosis in the search for new strategies against multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis. The study included 28 clinical M. tuberculosis strains, comprising 5 fully susceptible, 1 isoniazid-resistant, 17 MDR, 1 poly-resistant (streptomycin/isoniazid), 1 rifampicin-resistant and 3 XDR isolates, as well as the laboratory strain M. tuberculosis H37Rv. Minimum inhibitory concentrations (MICs) were determined using a modified chequerboard methodology in a BACTEC™ MGIT™ 960 System. Fractional inhibitory concentration indices (FICIs) were calculated, and synergy, indifference or antagonism was assessed. Whole-genome sequencing was performed to investigate the genetic basis of synergy, indifference or antagonism. The MIC50 and MIC90 values (MICs that inhibit 50% and 90% of the isolates, respectively) were, respectively, 0.5 mg/L and 1.0 mg/L for amikacin and 8 mg/L and 16 mg/L for doxycycline. The combination of amikacin and doxycycline showed a synergistic effect in 18 of the 29 strains tested and indifference in 11 strains. Antagonism was not observed. A streptomycin resistance mutation (K43R) was associated with indifference. In conclusion, the benefit of addition of doxycycline to an amikacin-containing regimen should be explored since in vitro results in this study indicate either synergy or indifference. Moreover, doxycycline also has immunomodulatory effects.

  8. MFS transporters of Candida species and their role in clinical drug resistance.

    PubMed

    K Redhu, Archana; Shah, Abdul H; Prasad, Rajendra

    2016-06-01

    ABC (ATP-binding cassette) and MFS (major facilitator superfamily) exporters, belonging to two different superfamilies, are one of the most prominent contributors of multidrug resistance (MDR) in yeast. While the role of ABC efflux pump proteins in the development of MDR is well documented, the MFS transporters which are also implicated in clinical drug resistance have not received due attention. The MFS superfamily is the largest known family of secondary active membrane carriers, and MFS exporters are capable of transporting a host of substrates ranging from small molecules, including organic and inorganic ions, to complex biomolecules, such as peptide and lipid moieties. A few of the members of the drug/H(+) antiporter family of the MFS superfamily function as multidrug transporters and employ downhill transport of protons to efflux their respective substrates. This review focuses on the recent developments in MFS of Candida and highlights their role in drug transport by using the example of the relatively well characterized promiscuous Mdr1 efflux pump of the pathogenic yeast C. albicans. PMID:27188885

  9. Involvement of miR-326 in chemotherapy resistance of breast cancer through modulating expression of multidrug resistance-associated protein 1.

    PubMed

    Liang, Zhongxing; Wu, Hui; Xia, James; Li, Yuhua; Zhang, Yawei; Huang, Ke; Wagar, Nicholas; Yoon, Younghyoun; Cho, Heidi T; Scala, Stefania; Shim, Hyunsuk

    2010-03-15

    Multidrug resistance-associated protein (MRP-1/ABCC1) transports a wide range of therapeutic agents and may play a critical role in the development of multidrug resistance (MDR) in tumor cells. However, the regulation of MRP-1 remains controversial. To explore whether miRNAs are involved in the regulation of MRP-1 expression and modulate the sensitivity of tumor cells to chemotherapeutic agents, we analyzed miRNA expression levels in VP-16-resistant MDR cell line, MCF-7/VP, in comparison with its parent cell line, MCF-7, using a miRNA microarray. MCF-7/VP overexpressed MRP-1 mRNA and protein not MDR-1 and BCRP. miR-326 was downregulated in MCF-7/VP compared to MCF-7. Additionally, miR-326 was downregulated in a panel of advanced breast cancer tissues and consistent reversely with expression levels of MRP-1. Furthermore, the elevated levels of miR-326 in the mimics-transfected VP-16-resistant cell line, MCF-7/VP, downregulated MRP-1 expression and sensitized these cells to VP-16 and doxorubicin. These findings demonstrate for the first time the involvement of miRNAs in multidrug resistance mediated by MRP-1 and suggest that miR-326 may be an efficient agent for preventing and reversing MDR in tumor cells.

  10. Silencing clusterin gene transcription on effects of multidrug resistance reversing of human hepatoma HepG2/ADM cells.

    PubMed

    Zheng, Wenjie; Sai, Wenli; Yao, Min; Gu, Hongbin; Yao, Yao; Qian, Qi; Yao, Dengfu

    2015-05-01

    Abnormal clusterin (CLU) expression is associated with multidrug resistance (MDR) of hepatocellular carcinoma (HCC). In the present study, the CLU expression was analyzed in human hepatoma cells and chemoresistant counterpart HepG2/ADM cells. Compared with L02 cells, the overexpression of cellular CLU was identified in HepG2, HepG2/ADM, SMMC7721, Hep3B ,and PLC cells and relatively lower expression in Bel-7404, SNU-739, and MHCC97H cells. Specific short hairpin RNAs (shRNAs) to silence CLU gene transcription were designed, and the most effective sequences were screened. After the HepG2/ADM cells transfected with shRNA-1, the inhibition of CLU expression was 73.68 % at messenger RNA (mRNA) level by real-time quantitative RT-PCR with obvious enhancement in cell chemosensitivity, increasing apoptosis induced by doxorubicin using fluorescence kit, and Rh-123 retention qualified with flow cytometry. Knockdown CLU also significantly decreased the drug efflux pump activity through the depression of MDR1/P-glycoprotein (q = 11.739, P < 0.001). Moreover, silencing CLU led to downregulation of β-catenin (q = 13.544, P = 0.001), suggesting that downregulation of CLU might be a key point to reverse multidrug resistance of HepG2/ADM cells. PMID:25600802

  11. Recurrence rate and progression of chondrosarcoma is correlated with heat shock protein expression

    PubMed Central

    TRIEB, KLEMENS; SULZBACHER, IRENE; KUBISTA, BERND

    2016-01-01

    Heat shock proteins (HSPs) are involved in tumour immunity, and are correlated with survival and drug resistance in numerous types of cancer. The present study investigated the expression of HSPs and multiple drug resistance (MDR) in human chondrosarcoma. HSP and P-glycoprotein (the MDR1 gene product) expression was evaluated by immunohistochemical analysis of paraffin-embedded sections obtained from 37 patients with chondrosarcoma (19 male and 18 female; aged 33–85 years; mean age, 48.5 years). HSP73 and 90 were significantly overexpressed in patients with local recurrence: HSP73 was expressed in 7/7 patients (100%) with local recurrence and 9/18 patients (50%) without recurrence (P<0.02), while HSP90 was expressed in all patients with recurrence but only 8/18 (44%) without recurrence (P<0.02). A marked association was also identified between HSP expression and survival. HSP72 and 73 were significantly overexpressed in tumours from patients who succumbed to the disease (all positive for HSP72 and 73; P<0.05). No differences were observed between HSP27, 73 or 90-positive or -negative tumours according to age or gender. In addition, HSP72 expression was correlated with differentiation of the tumours (P<0.02). These results indicate that HSP72, 73 and 90 may function as novel prognostic markers for chondrosarcoma, and initiate further studies regarding the use of such markers for the identification of patients with poor prognosis. PMID:26870241

  12. Beneficial effect of tetrandrine on refractory epilepsy via suppressing P-glycoprotein.

    PubMed

    Chen, Yinghui; Xiao, Xia; Wang, Cuicui; Jiang, Huiyuan; Hong, Zhen; Xu, Guoxiong

    2015-01-01

    Patients with refractory epilepsy are resistance to antiepileptic drugs (AEDs). The mechanisms of drug resistance are varied, but one of them is the overexpression of multidrug transporters, such as P-glycoprotein (P-gp), in the brain. Tetrandrine (TTD) is a bis-benzylisoquinoline alkaloid isolated from the root of Stephania tetrandra (S, Moore) and is found to have a favorable effect against multidrug resistance (MDR) in chemotherapy. However, whether TTD affects AEDs in refractory epilepsy is unknown. In this study, we investigated the change in AED treatment efficacy in doxorubicin-induced drug resistant cells after TTD administration. We also examined the effect of TTD on seizure behaviors in the refractory epileptic rats, specifically the expression of MDR1 mRNA and P-gp protein in the cortex and hippocampus of the refractory epileptic rats. Our results demonstrated that TTD decreased cell resistance to phenytoin and valproate. TTD decreased seizure rate and increased the treatment efficacy of AEDs by reducing the expression of P-gp at mRNA and protein levels in vivo. These data support the use of TTD as an adjuvant drug for treating refractory epilepsy. PMID:25233150

  13. Targeting ABCB1 and ABCC1 with their Specific Inhibitor CBT-1® can Overcome Drug Resistance in Osteosarcoma.

    PubMed

    Fanelli, Marilù; Hattinger, Claudia Maria; Vella, Serena; Tavanti, Elisa; Michelacci, Francesca; Gudeman, Beth; Barnett, Daryl; Picci, Piero; Serra, Massimo

    2016-01-01

    Clinical treatment response achievable with conventional chemotherapy in high-grade osteosarcoma (OS) is severely limited by the presence of intrinsic or acquired drug resistance, which in previous studies has been mainly addressed for overexpression of ABCB1 (MDR1/P-glycoprotein). This study was aimed to estimate the impact on OS drug resistance of a group of ATP binding cassette (ABC) transporters, which in other human tumors have been associated with unresponsiveness to the drugs that represent the backbone of multidrug treatment regimens for OS (doxorubicin, methotrexate, cisplatin). By using a group of 6 drug-sensitive and 20 drug-resistant human OS cell lines, the most relevant transporter which proved to be associated with the degree of drug resistance in OS cells, in addition to ABCB1, was ABCC1. We therefore evaluated the in vitro activity of the orally administrable ABCB1/ABCC1 inhibitor CBT-1(®) (Tetrandrine, NSC-77037). We found that in our OS cell lines this agent was able to revert the ABCB1/ABCC1-mediated resistance against doxorubicin, as well as against the drugs used in second-line OS treatments that are substrates of these transporters (taxotere, etoposide, vinorelbine). Our findings indicated that inhibiting ABCB1 and ABCC1 with CBT-1(®), used in association with conventional chemotherapeutic drugs, may become an interesting new therapeutic option for unresponsive or relapsed OS patients. PMID:26548759

  14. Investigations on the 4-quinolone-3-carboxylic acid motif. 6. Synthesis and pharmacological evaluation of 7-substituted quinolone-3-carboxamide derivatives as high affinity ligands for cannabinoid receptors.

    PubMed

    Pasquini, Serena; De Rosa, Maria; Ligresti, Alessia; Mugnaini, Claudia; Brizzi, Antonella; Caradonna, Nicola P; Cascio, Maria Grazia; Bolognini, Daniele; Pertwee, Roger G; Di Marzo, Vincenzo; Corelli, Federico

    2012-12-01

    Within our studies on structure-activity relationships of 4-quinolone-3-carboxamides as cannabinoid ligands, a new series of compounds characterized by a fluoro or phenylthio group at 7-position and different substituents at N1 and carboxamide nitrogen were synthesized and evaluated for their binding ability to cannabinoid type 1 (CB1) and type 2 (CB2) receptors. Most of the compounds showed affinity for one or both cannabinoid receptors at nanomolar concentration, with K(i)(CB1) and K(i)(CB2) values ranging from 2.45 to >10,000 nM and from 0.09 to 957 nM, respectively. The N-(3,4-dichlorobenzyl)amide derivatives 27 and 40 displayed relatively low affinity, but high selectivity towards the CB1 receptor. Compounds 4 and 40, a CB2 and a CB1 ligand, respectively, behaved as partial agonists in the [(35)S]GTPγS assay. They showed very low permeability through (MDCK-MDR1) cells and might, therefore, represent possible lead structures for further optimization in the search for cannabinoid ligands unable to cross the blood-brain barrier. PMID:23085772

  15. Tissue-specific regulation of pregnane X receptor in cancer development and therapy

    PubMed Central

    2014-01-01

    As a ligand-dependent transcription factor of the nuclear hormone receptor superfamily, the pregnane X receptor (PXR) has a multitude of functions including regulating xenobiotic and cholesterol metabolism, energy homeostasis, gut mucosal defense, and cancer development. Whereas the detoxification functions of PXR have been widely studied and well established, the role of PXR in cancer has become controversial. With more than 60% of non-prescription and prescription drugs being metabolized by cytochrome P450 enzyme 3A4 (CYP3A4), a transcriptional target of PXR, insights into the regulation of PXR during systemic administration of novel treatment modalities will lead to a better understanding of PXR function in the context of human disease. Previous studies have suggested that PXR activation decreases drug sensitivity and augments chemoresistance in certain colon cancers mainly through the upregulation of CYP3A4 and multidrug resistance protein-1 (MDR1). Later studies suggest that downregulation of PXR expression may be oncogenic in hormone-dependent breast and endometrial cancers by reducing estrogen metabolism via CYP3A4; thus, higher estradiol concentrations contribute to carcinogenesis. These results suggest a differential role of PXR in tumor growth regulation dependent on tissue type and tumor microenvironment. Here, we will summarize the various mechanisms utilized by PXR to induce its diverse effects on cancerous tissues. Moreover, current approaches will be explored to evaluate the exploitation of PXR-mediated pathways as a novel mechanistic approach to cancer therapy. PMID:24690092

  16. Can antiretroviral therapy be tailored to each human immunodeficiency virus-infected individual? Role of pharmacogenomics

    PubMed Central

    Asensi, Victor; Collazos, Julio; Valle-Garay, Eulalia

    2015-01-01

    Pharmacogenetics refers to the effect of single nucleotide polymorphisms (SNPs) within human genes on drug therapy outcome. Its study might help clinicians to increase the efficacy of antiretroviral drugs by improving their pharmacokinetics and pharmacodynamics and by decreasing their side effects. HLAB*5701 genotyping to avoid the abacavir-associated hypersensitivity reaction (HSR) is a cost-effective diagnostic tool, with a 100% of negative predictive value, and, therefore, it has been included in the guidelines for treatment of human immunodeficiency virus (HIV) infection. HALDRB*0101 associates with nevirapine-induced HSR. CYP2B6 SNPs modify efavirenz plasma levels and their genotyping help decreasing its central nervous system, hepatic and HSR toxicities. Cytokines SNPs might influence the development of drug-associated lipodystrophy. APOA5, APOB, APOC3 and APOE SNPs modify lipids plasma levels and might influence the coronary artery disease risk of HIV-infected individuals receiving antiretroviral therapy. UGT1A1*28 and ABCB1 (MDR1) 3435C > T SNPs modify atazanavir plasma levels and enhance hyperbilirubinemia. Much more effort needs to be still devoted to complete large prospective studies with multiple SNPs genotyping in order to reveal more clues about the role played by host genetics in antiretroviral drug efficacy and toxicity. PMID:26279978

  17. Can antiretroviral therapy be tailored to each human immunodeficiency virus-infected individual? Role of pharmacogenomics.

    PubMed

    Asensi, Victor; Collazos, Julio; Valle-Garay, Eulalia

    2015-08-12

    Pharmacogenetics refers to the effect of single nucleotide polymorphisms (SNPs) within human genes on drug therapy outcome. Its study might help clinicians to increase the efficacy of antiretroviral drugs by improving their pharmacokinetics and pharmacodynamics and by decreasing their side effects. HLAB*5701 genotyping to avoid the abacavir-associated hypersensitivity reaction (HSR) is a cost-effective diagnostic tool, with a 100% of negative predictive value, and, therefore, it has been included in the guidelines for treatment of human immunodeficiency virus (HIV) infection. HALDRB*0101 associates with nevirapine-induced HSR. CYP2B6 SNPs modify efavirenz plasma levels and their genotyping help decreasing its central nervous system, hepatic and HSR toxicities. Cytokines SNPs might influence the development of drug-associated lipodystrophy. APOA5, APOB, APOC3 and APOE SNPs modify lipids plasma levels and might influence the coronary artery disease risk of HIV-infected individuals receiving antiretroviral therapy. UGT1A1*28 and ABCB1 (MDR1) 3435C > T SNPs modify atazanavir plasma levels and enhance hyperbilirubinemia. Much more effort needs to be still devoted to complete large prospective studies with multiple SNPs genotyping in order to reveal more clues about the role played by host genetics in antiretroviral drug efficacy and toxicity. PMID:26279978

  18. Characterization of multidrug resistance P-glycoprotein transport function with an organotechnetium cation

    SciTech Connect

    Piwnica-Worms, D.; Vallabhaneni, V.R.; Kronauge, J.F.

    1995-09-26

    Multidrug resistance (MDR) in mammalian cells and tumors is associated with overexpression of an {approximately}170 integral membrane efflux transporter, the MDR1 P-glycoprotein. Hexakis(2-methoxyisobutyl isonitrile) technetium(I) (Tc-SESTAMIBI), a {gamma}-emitting lipophilic cationic metallopharmaceutical, has recently been shown to be a P-glycoprotein transport substrate. Exploiting the negligible lipid membrane adsorption properties of this organometallic substrate, we studied the transport kinetics, pharmacology, drug binding, and modulation of P-glycoprotein in cell preparations derived from a variety of species and selection strategies, including SW-1573, V79, Alex, and CHO drug-sensitive cells and in 77A, LZ-8, and Alex/A.5 MDR cells. Rapid cell accumulation (T{sub 1/2} {approx} 6 min) of the agent to a steady state was observed which was inversely proportional to immunodetectable levels of P-glycoprotein. Many MDR cytotoxic agents inhibited P-glycoprotein-mediated Tc-SESTAMIBI efflux, thereby enhancing organometallic cation accumulation. 70 refs., 7 figs., 2 tabs.

  19. Positive selection of gene-modified cells increases the efficacy of pancreatic cancer suicide gene therapy.

    PubMed

    Martinez-Quintanilla, Jordi; Cascallo, Manel; Gros, Alena; Fillat, Cristina; Alemany, Ramon

    2009-11-01

    Thymidine kinase (TK)-mediated suicide gene therapy has been considered for the treatment of pancreatic cancer. However, despite a bystander effect, the proportion of transduced tumor cells has proven too low to result in efficacy. We propose the use of a drug-selectable marker (MDR1) to enrich TK-expressing cells using chemotherapy. This enrichment or positive selection phase may increase the efficacy of suicide gene therapy. To test this strategy, we generated stable NP18MDR/TK-GFP transfectants and showed docetaxel resistance in vivo. Mixed tumors of MDR/TK-expressing cells and parental NP18 cells were established and docetaxel was used to increase the proportion of TK-expressing cells. After this positive selection phase, suicide gene therapy with ganciclovir was applied. Upon positive selection, the proportion of TK-expressing cells increased from 4% to 22%. Subsequent suicide gene therapy was more effective compared with a control group without positive selection. Starting with 10% of TK-expressing cells the positive-negative selection strategy completely inhibited tumor growth. Taken together, these results suggest that a positive-negative selection strategy based on MDR and TK genes represents an efficient way to increase the proportion of TK-expressing cells in the tumor and the efficacy of TK-mediated suicide gene therapy.

  20. The butter flavorant, diacetyl, exacerbates β-amyloid cytotoxicity.

    PubMed

    More, Swati S; Vartak, Ashish P; Vince, Robert

    2012-10-15

    Diacetyl (DA), an ubiquitous butter-flavoring agent, was found to influence several aspects of amyloid-β (Aβ) aggregation--one of the two primary pathologies associated with Alzheimer's disease. Thioflavin T fluorescence and circular dichroism spectroscopic measurements revealed that DA accelerates Aβ¹⁻⁴² aggregation into soluble and ultimately insoluble β-pleated sheet structures. DA was found to covalently bind to Arg⁵ of Aβ¹⁻⁴² through proteolytic digestion-mass spectrometric experiments. These biophysical and chemical effects translated into the potentiation of Aβ¹⁻⁴² cytotoxicity by DA toward SH-SY5Y cells in culture. DA easily traversed through a MDR1-MDCK cell monolayer, an in vitro model of the blood-brain barrier. Additionally, DA was found not only to be resistant to but also inhibitory toward glyoxalase I, the primary initiator of detoxification of amyloid-promoting reactive dicarbonyl species that are generated naturally in large amounts by neuronal tissue. In light of the chronic exposure of industry workers to DA, this study raises the troubling possibility of long-term neurological toxicity mediated by DA.

  1. Simultaneous determination of quercetin, kaempferol and isorhamnetin accumulated human breast cancer cells, by high-performance liquid chromatography.

    PubMed

    Wang, Yi; Cao, Jiang; Weng, Jian-Hua; Zeng, Su

    2005-09-01

    Quercetin, kaempferol and isorhamnetin are the most important constituents in ginkgo flavonoids. A simple, rapid and sensitive high-performance liquid chromatography method was developed to simultaneously determine quercetin, kaempferol and isorhamnetin absorped by human breast cancer cells. Cells were treated with ginkgo flavonols and then lysed with Triton-X 100. The flavonols in the samples were measured by RP-HPLC with a C18 column after a simple extraction with a mixture of ether and acetone. The mobile phase contained phosphate buffer (pH 2.0; 10 mM) tetrahydrofuran, methanol and isopropanol (65:15:10:20, v/v/v/v). The ultraviolet detector was operated at 380 nm. The calibration curve was linear from 0.1 to 1.0 microM (r > 0.999) for each flavonol. The mean extraction efficiency was about 70%. The recovery of the assay was between 98.9 and 100.6%. The limit of detection was 0.01 microM for quercetin and kaempferol and 0.05 microM for isorhamnetin. The limit of quantitation was 0.1 microM (R.S.D.<10%) for each flavonol. The intra- and inter-day coefficients of variation were less than 10% (R.S.D.). The validated method was applied to quantify quercetin, kaempferol and isorhamnetin in human breast cancer Bcap37 and Bcap37/MDR1 cells. PMID:15905060

  2. Molecular profiling of prostate cancer derived exosomes may reveal a predictive signature for response to docetaxel.

    PubMed

    Kharaziha, Pedram; Chioureas, Dimitris; Rutishauser, Dorothea; Baltatzis, George; Lennartsson, Lena; Fonseca, Pedro; Azimi, Alireza; Hultenby, Kjell; Zubarev, Roman; Ullén, Anders; Yachnin, Jeffrey; Nilsson, Sten; Panaretakis, Theocharis

    2015-08-28

    Docetaxel is a cornerstone treatment for metastatic, castration resistant prostate cancer (CRPC) which remains a leading cause of cancer-related deaths, worldwide. The clinical usage of docetaxel has resulted in modest gains in survival, primarily due to the development of resistance. There are currently no clinical biomarkers available that predict whether a CRPC patient will respond or acquire resistance to this therapy. Comparative proteomics analysis of exosomes secreted from DU145 prostate cancer cells that are sensitive (DU145 Tax-Sen) or have acquired resistance (DU145 Tax-Res) to docetaxel, demonstrated significant differences in the amount of exosomes secreted and in their molecular composition. A panel of proteins was identified by proteomics to be differentially enriched in DU145 Tax-Res compared to DU145 Tax-Sen exosomes and was validated by western blotting. Importantly, we identified MDR-1, MDR-3, Endophilin-A2 and PABP4 that were enriched only in DU145 Tax-Res exosomes. We validated the presence of these proteins in the serum of a small cohort of patients. DU145 cells that have uptaken DU145 Tax-Res exosomes show properties of increased matrix degradation. In summary, exosomes derived from DU145 Tax-Res cells may be a valuable source of biomarkers for response to therapy.

  3. P-glycoprotein substrate transport assessed by comparing cellular and vesicular ATPase activity.

    PubMed

    Nervi, Pierluigi; Li-Blatter, Xiaochun; Aänismaa, Päivi; Seelig, Anna

    2010-03-01

    We compared the P-glycoprotein ATPase activity in inside-out plasma membrane vesicles and living NIH-MDR1-G185 cells with the aim to detect substrate transport. To this purpose we used six substrates which differ significantly in their passive influx through the plasma membrane. In cells, the cytosolic membrane leaflet harboring the substrate binding site of P-glycoprotein has to be approached by passive diffusion through the lipid membrane, whereas in inside-out plasma membrane vesicles, it is accessible directly from the aqueous phase. Compounds exhibiting fast passive influx compared to active efflux by P-glycoprotein induced similar ATPase activity profiles in cells and inside-out plasma membrane vesicles, because their concentrations in the cytosolic leaflets were similar. Compounds exhibiting similar influx as efflux induced in contrast different ATPase activity profiles in cells and inside-out vesicles. Their concentration was significantly lower in the cytosolic leaflet of cells than in the cytosolic leaflet of inside-out membrane vesicles, indicating that P-glycoprotein could cope with passive influx. P-glycoprotein thus transported all compounds at a rate proportional to ATP hydrolysis (i.e. all compounds were substrates). However, it prevented substrate entry into the cytosol only if passive influx of substrates across the lipid bilayer was in a similar range as active efflux. PMID:20004641

  4. Genetic characteristics of Sasang typology: a systematic review.

    PubMed

    Sohn, Kyungwoo; Jeong, Ansuk; Yoon, Miyoung; Lee, Sunkyung; Hwang, Sangmoon; Chae, Han

    2012-12-01

    A systematic review on studies related to the genetic characteristics of Sasang types was conducted with the goal of delineating genetic characteristics of Sasang typology. Six electronic databases of up to the March 2011 were examined with the key words of Sasang typology, constitution, and genetics in both Korean and English. Predefined review criteria were used, including demographic characteristics, type classification methods, genotyping methods, and genotypes. Fifty-nine potentially relevant studies were identified and 40 peer reviewed research articles that contained genetic data were included. Fourteen articles reported statistically significant differences among Sasang types, which are heritability, structural variation, genome-wide screening, and pathophysiological function. Although significant genotypes were reported with vWA, CSF1PO, Penta D, HLA-Cw*04, HLA-Cw*07, PPAR-γ, MDR1, IL-α, IL-β, and IL-6 receptor, results of the review indicate that there was no conclusive genotype related to the Sasang typology. Considering the features of Sasang typology, it is recommended that the macroscopic systems medical approach on genetics be employed, rather than the single genes association approach.

  5. Reporter dyes demonstrate functional expression of multidrug resistance proteins in the marine flatworm Macrostomum lignano: the sponge-derived dye Ageladine A is not a substrate of these transporters.

    PubMed

    Tietje, Kristin; Rivera-Ingraham, Georgina; Petters, Charlotte; Abele, Doris; Dringen, Ralf; Bickmeyer, Ulf

    2013-10-01

    The marine plathyhelminth Macrostomum lignano was recently isolated from Adriatic shore sediments where it experiences a wide variety of environmental challenges, ranging from hypoxia and reoxygenation, feeding on toxic algae, to exposure to anthropogenic contaminants. As multidrug resistance transporters constitute the first line of defense against toxins and toxicants we have studied the presence of such transporters in M. lignano in living animals by applying optical methods and pharmacological inhibitors that had been developed for mammalian cells. Application of the MDR1 inhibitor Verapamil or of the MRP1 inhibitors MK571 or Probenecid increased the intracellular fluorescence of the reporter dyes Fura-2 am, Calcein am, Fluo-3 am in the worms, but did not affect their staining with the dyes Rhodamine B, CMFDA or Ageladine A. The marine sponge alkaloid Ageladine A remained intracellularly trapped for several days in the worms, suggesting that it does not serve as substrate of multidrug resistance exporters. In addition, Ageladine A did not affect multidrug resistance-associated protein (MRP)-mediated dye export from M. lignano or the MRP1-mediated glutathione (GSH) export from cultured rat brain astrocytes. The data obtained demonstrate that life-imaging is a useful tool to address physiological drug export from intact marine transparent flatworms by using multiphoton scanning microscopy.

  6. Maytansinoid immunoconjugate IMGN901 is cytotoxic in a three-dimensional culture model of multiple myeloma

    PubMed Central

    Nierste, Brittany A; Gunn, Ellen J; Whiteman, Kathleen R; Lutz, Robert J; Kirshner, Julia

    2016-01-01

    Environmental-mediated drug-resistance (EM-DR) presents a major challenge for therapeutic development. Tissue microenvironment in the form of extracellular matrix, soluble factors, and stroma contribute to EM-DR. In multiple myeloma (MM), drug-resistance has hindered treatment success with 5-year survival rates remaining <50%. Here we evaluated IMGN901, a maytansinoid immunoconjugate, for its ability to overcome EM-DR alone or in combination with lenalidomide or dexamethasone. We show that while adhesion of MM cells to the extracellular matrix reduces potency of IMGN901, it remains cytotoxic with an average LC50=43 nM. However, only a combination of IMGN901, lenalidomide, and dexamethasone was able to overcome drug-resistance arising from the direct contact between MM and stromal cells. We demonstrate that multi-drug resistance protein-1 (MDR-1) was upregulated in MM cells grown in contact with stroma, likely responsible for the observed resistance. This study emphasizes the importance of incorporating the elements of tumor microenvironment during preclinical testing of novel therapeutics. PMID:27335686

  7. Structural polymorphism in the promoter of pfmrp2 confers Plasmodium falciparum tolerance to quinoline drugs

    PubMed Central

    Mok, Sachel; Liong, Kek-Yee; Lim, Eng-How; Huang, Ximei; Zhu, Lei; Preiser, Peter Rainer; Bozdech, Zbynek

    2014-01-01

    Drug resistance in Plasmodium falciparum remains a challenge for the malaria eradication programmes around the world. With the emergence of artemisinin resistance, the efficacy of the partner drugs in the artemisinin combination therapies (ACT) that include quinoline-based drugs is becoming critical. So far only few resistance markers have been identified from which only two transmembrane transporters namely PfMDR1 (an ATP-binding cassette transporter) and PfCRT (a drug-metabolite transporter) have been experimentally verified. Another P. falciparum transporter, the ATP-binding cassette containing multidrug resistance-associated protein (PfMRP2) represents an additional possible factor of drug resistance in P. falciparum. In this study, we identified a parasite clone that is derived from the 3D7 P. falciparum strain and shows increased resistance to chloroquine, mefloquine and quinine through the trophozoite and schizont stages. We demonstrate that the resistance phenotype is caused by a 4.1 kb deletion in the 5′ upstream region of the pfmrp2 gene that leads to an alteration in the pfmrp2 transcription and thus increased level of PfMRP2 protein. These results also suggest the importance of putative promoter elements in regulation of gene expression during the P. falciparum intra-erythrocytic developmental cycle and the potential of genetic polymorphisms within these regions to underlie drug resistance. PMID:24372851

  8. ATP-dependent transport of vinblastine in vesicles from human multidrug-resistant cells

    SciTech Connect

    Horio, M.; Gottesman, M.M.; Pastan, I. )

    1988-05-01

    Resistance of human cancer cells to multiple cytotoxic hydrophobic agents (multidrug resistance) is due to overexpression of the MDR1 gene, whose product is the plasma membrane P-glycoprotein. Plasma membrane vesicles partially purified from multidrug-resistant human KB carcinoma cells, but not from drug-sensitive cells, accumulate ({sup 3}H)vinblastine in an ATP-dependent manner. This transport is osmotically sensitive, with an apparent K{sub m} of 38 {mu}M for ATP and of {approx} 2 {mu}M for vinblastine. The nonhydrolyzable analog adenosine 5{prime}-({beta},{gamma}-imido)triphosphate does not substitute for ATP but is a competitive inhibitor of ATP for the transport process. Vanadate, and ATPase inhibitor, is a potent noncompetitive inhibitor of transport. These results indicate that hydrolysis of ATP is probably required for active transport vinblastine. Several other drugs to which multidrug-resistant cell lines are resistant inhibit transport, with relative potencies as follows: vincristine > actinomycin D > daunomycin > colchicine = puromycin. Verapamil and quinidine, which reverse the multidrug-resistance phenotype, are good inhibitors of the transport process. These results confirm that multidrug-resistant cells express an energy-dependent plasma membrane transporter for hydrophobic drugs, and establish a system for the detailed biochemical analysis of this transport process.

  9. Molecular profiling of prostate cancer derived exosomes may reveal a predictive signature for response to docetaxel

    PubMed Central

    Kharaziha, Pedram; Chioureas, Dimitris; Rutishauser, Dorothea; Baltatzis, George; Lennartsson, Lena; Fonseca, Pedro; Azimi, Alireza; Hultenby, Kjell; Zubarev, Roman; Ullén, Anders; Yachnin, Jeffrey; Nilsson, Sten; Panaretakis, Theocharis

    2015-01-01

    Docetaxel is a cornerstone treatment for metastatic, castration resistant prostate cancer (CRPC) which remains a leading cause of cancer-related deaths, worldwide. The clinical usage of docetaxel has resulted in modest gains in survival, primarily due to the development of resistance. There are currently no clinical biomarkers available that predict whether a CRPC patient will respond or acquire resistance to this therapy. Comparative proteomics analysis of exosomes secreted from DU145 prostate cancer cells that are sensitive (DU145 Tax-Sen) or have acquired resistance (DU145 Tax-Res) to docetaxel, demonstrated significant differences in the amount of exosomes secreted and in their molecular composition. A panel of proteins was identified by proteomics to be differentially enriched in DU145 Tax-Res compared to DU145 Tax-Sen exosomes and was validated by western blotting. Importantly, we identified MDR-1, MDR-3, Endophilin-A2 and PABP4 that were enriched only in DU145 Tax-Res exosomes. We validated the presence of these proteins in the serum of a small cohort of patients. DU145 cells that have uptaken DU145 Tax-Res exosomes show properties of increased matrix degradation. In summary, exosomes derived from DU145 Tax-Res cells may be a valuable source of biomarkers for response to therapy. PMID:25844599

  10. Annonaceous acetogenins reverses drug resistance of human hepatocellular carcinoma BEL-7402/5-FU and HepG2/ADM cell lines

    PubMed Central

    Qian, Jun-Qiang; Sun, Pei; Pan, Zhan-Yu; Fang, Zhi-Zhong

    2015-01-01

    Hepatocellular carcinoma (HCC) is the most common tumor in worldwide and chemotherapy resistant is a severe obstacle in HCC treatment. Annonaceous acetogenins was a nature compound from Uvaria accuminata and it has show the anti-tumor proliferation activity in many types cancer. In this study, we showed that annonaceous acetogenins is correlated with the drug resistance reversal in human hepatocellular carcinoma BEL-7402/5-FU and HepG2/ADM cell lines. We found that cell apoptosis was improved and cell cycle was arrested, further, multidrug-resistance proteins such as MDR1, MRP1, Topo-IIα, GST-π, cyclin D1, Survivin and bcl-2 are down-regulated, however, intracellular Rh-123 and caspase-3/8 was up-regulated by Annonaceous acetogenins treatment. We also found that there was a decreased activity of NF-κB and Akt in Annonaceous acetogenins treatment groups. Therefore, we demonstrate that Akt/NF-κB pathway was involved in Annonaceous acetogenins reverses drug resistance of human hepatocellular carcinoma cells. PMID:26617951

  11. Ensemble Rule-Based Classification of Substrates of the Human ABC-Transporter ABCB1 Using Simple Physicochemical Descriptors.

    PubMed

    Demel, Michael A; Kraemer, Oliver; Ettmayer, Peter; Haaksma, Eric; Ecker, Gerhard F

    2010-03-15

    Within the last decades, the detailed knowledge on the impact of membrane bound drug efflux transporters of the ATP binding cassette (ABC) protein family on the pharmacological profile of drugs has enormously increased. Especially, ABCB1 (P-glycoprotein, P-gp, MDR1) has attracted particular interest in medicinal chemistry, since it determines the clinical efficacy, side effects and toxicity risks of drug candidates. Based on this, the development of in silico models that provide rapid and cost-effective screening tools for the classification of substrates and nonsubstrates of ABCB1 is an urgent need in contemporary ADMET profiling. A characteristic hallmark feature of this transporter is its polyspecific ligand recognition pattern. In this study we describe a method for classifying ABCB1 ligands in terms of simple, conjunctive rules (RuleFit) based on interpretable ADMET features. The retrieved results showed that models based on large, very diverse data sets gave better classification performance than models based on smaller, more homogenous training sets. The best model achieved gave a correct classification rate of 0.90 for an external validation set. Furthermore, from the interpretation of the best performing model it could be concluded that in comparison to nonsubstrates ABCB1 substrates generally show a higher number of hydrogen-bond acceptors, are more flexible and exhibit higher logP values.

  12. A Dual-Fluorescence High-Throughput Cell Line System for Probing Multidrug Resistance

    PubMed Central

    Brimacombe, Kyle R.; Hall, Matthew D.; Auld, Douglas S.; Inglese, James; Austin, Christopher P.; Fung, King-Leung

    2009-01-01

    Abstract The efflux pump P-glycoprotein (ATP-binding cassette B1, multidrug resistance [MDR] 1, P-gp) has long been known to contribute to MDR against cancer chemotherapeutics. We describe the development of a dual-fluorescent cell line system to allow multiplexing of drug-sensitive and P-gp-mediated MDR cell lines. The parental OVCAR-8 human ovarian carcinoma cell line and the isogenic MDR NCI/ADR-RES subline, which stably expresses high levels of endogenous P-gp, were transfected to express the fluorescent proteins Discosoma sp. red fluorescent protein DsRed2 and enhanced green fluorescent protein, respectively. Co-culture conditions were defined, and fluorescent barcoding of each cell line allowed for the direct, simultaneous comparison of resistance to cytotoxic compounds in sensitive and MDR cell lines. We show that this assay system retains the phenotypes of the original lines and is suitable for multiplexing using confocal microscopy, flow cytometry, or laser scanning microplate cytometry in 1,536-well plates, enabling the high-throughput screening of large chemical libraries. PMID:19548831

  13. The association of statins and taxanes: an efficient combination trigger of cancer cell apoptosis

    PubMed Central

    Follet, J; Corcos, L; Baffet, G; Ezan, F; Morel, F; Simon, B; Le Jossic-Corcos, C

    2012-01-01

    Background: Cancer cell killing might be achieved by the combined use of available drugs. Statins are major anti-hypercholesterolemia drugs, which also trigger apoptosis of many cancer cell types, while docetaxel is a potent microtubule-stabilising agent. Methods: Here, we looked at the combined effects of lovastatin and docetaxel in cancer cells. Results: Whole transcriptome microarrays in HGT-1 gastric cancer cells demonstrated that lovastatin strongly suppressed expression of genes involved in cell division, while docetaxel had very little transcriptional effects. Both drugs triggered apoptosis, and their combination was more than additive. A marked rise in the cell-cycle inhibitor p21, together with reduction of aurora kinases A and B, cyclins B1 and D1 proteins was induced by lovastatin alone or in combination with docetaxel. The drug treatments induced the proteolytic cleavage of procaspase-3, a drop of the anti-apoptotic Mcl-1 protein, Poly-ADP-Ribose Polymerase and Bax. Strikingly, docetaxel-resistant HGT-1 cell derivatives overexpressing the MDR-1 gene were much more sensitive to lovastatin than docetaxel-sensitive cells. Conclusion: These results suggest that the association of lovastatin and docetaxel, or lovastatin alone, shows promise as plausible anticancer strategies, either as a direct therapeutic approach or following acquired P-glycoprotein-dependent resistance. PMID:22294184

  14. Surface-epitope masking (SEM): an immunological subtraction approach for developing monoclonal antibodies targeting surface-expressed molecules.

    PubMed

    Goldstein, Neil I; Fisher, Paul B

    2007-01-01

    An immunological subtraction approach, surface-epitope masking (SEM), is described that permits the efficient and selective production of monoclonal antibodies (MAbs) reacting with both known and unknown molecules expressed on the cell surface. The tenet underlying SEM involves blocking (masking) of shared antigens between two target populations, a "driver" and a "tester," and using appropriately modified surface-masked "tester" cells to generate MAbs reacting with surface antigens unique to the "tester population" that differentiate the two antigen sources. SEM has been employed to develop MAbs that react with the multidrug resistance surface-expressed P-glycoprotein (MDR-1) and the human interferon-gamma receptor and two potentially novel tumor-associated antigens (TAAs) expressed on the surface of prostate carcinoma and breast carcinoma cells. In principle, the SEM approach provides an uncomplicated and effective means of developing MAbs, which can also be used to identify genes, associated with important cellular processes involved in normal physiology, such as growth, aging, differentiation, and development. In addition, this strategy is amenable to produce MAbs and identify genes associated with specific disease states, including cancer, neurodegeneration, autoimmunity, and infection with pathogenic agents. PMID:18217690

  15. Reversal of Multidrug Resistance in Mouse Lymphoma Cells by Extracts and Flavonoids from Pistacia integerrima.

    PubMed

    Rauf, Abdur; Uddin, Ghias; Raza, Muslim; Ahmad, Bashir; Jehan, Noor; Siddiqui, Bina S; Molnar, Joseph; Csonka, Akos; Szabo, Diana

    2016-01-01

    Phytochemical investigation of Pistacia integerrima has highlighted isolation of two known compounds naringenin (1) and dihydrokaempferol (2). A crude extract and these isolated compounds were here evaluated for their effects on reversion of multidrug resistance (MDR) mediated by P-glycoprotein (P-gp). The multidrug resistance P-glycoprotein is a target for chemotherapeutic drugs from cancer cells. In the present study rhodamine- 123 exclusion screening test on human mdr1 gene transfected mouse gene transfected L5178 and L5178Y mouse T-cell lymphoma cells showed excellent MDR reversing effects in a dose dependent manner. In-silico molecular docking investigations demonstrated a common binding site for Rhodamine123, and compounds naringenin and dihydrokaempferol. Our results showed that the relative docking energies estimated by docking softwares were in satisfactory correlation with the experimental activities. Preliminary interaction profile of P-gp docked complexes were also analysed in order to understand the nature of binding modes of these compounds. Our computational investigation suggested that the compounds interactions with the hydrophobic pocket of P-gp are mainly related to the inhibitory activity. Moreover this study s a platform for the discovery of novel natural compounds from herbal origin, as inhibitor molecules against the P-glycoprotein for the treatment of cancer. PMID:26838254

  16. Hexamethylene bisacetamide induces programmed cell death (apoptosis) and down-regulates BCL-2 expression in human myeloma cells.

    PubMed

    Siegel, D S; Zhang, X; Feinman, R; Teitz, T; Zelenetz, A; Richon, V M; Rifkind, R A; Marks, P A; Michaeli, J

    1998-01-01

    Multiple myeloma (MM) is a B cell malignancy characterized by the expansion of monoclonal Ig-secreting plasma cells with low proliferative activity. It is postulated that inhibition of physiologic cell death is an underlying factor in the pathophysiology of MM. The development of chemoresistance is a common feature in patients with MM. In the present studies, hexamethylene bisacetamide (HMBA), a hybrid polar compound that is a potent inducer of terminal differentiation of various transformed cells, is shown to inhibit the growth of several human myeloma cell lines (ARP-1, U266, and RPMI 8226), including doxorubicin-resistant RPMI 8226 variants that overexpress the multidrug-resistance gene, MDR-1, and its product, p-glycoprotein. In addition to growth arrest and suppression of clonogenicity, HMBA induces apoptosis both in freshly isolated human myeloma cells and in cell lines, as determined by morphologic alterations, cell cycle distribution and endonucleosomal DNA fragmentation. Further, HMBA decreases BCL-2 protein expression in myeloma cells within 12-48 hr. Overexpression of BCL-2 protein in ARP-1 cells confers resistance to HMBA-induced apoptosis. Taken together, these data suggest that HMBA is a potent inducer of apoptosis in human myeloma cells, which may act through suppressing the anti-apoptotic function of the bcl-2 gene. HMBA, and related hybrid polar compounds, may prove useful in the management of this presently incurable disease.

  17. Cloning and expression of MDR transporters from marine bivalves, and their potential use in biomonitoring.

    PubMed

    Feldstein, Tamar; Nelson, Nathan; Mokady, Ofer

    2006-07-01

    Multidrug resistance transporters (MDRs) are excellent candidates for molecular-level biomonitoring - they function in exporting xenobiotic compounds and their expression is inducible. However, currently available MDR sequence information from aquatic invertebrates is partial and mostly biased towards the conserved ATPase domain. In the present study, two genes belonging to the MDR/TAP (ABCB) family were cloned and characterized from the bivalve Brachidontes pharaonis, which thrives in rocky environments along the Israeli Mediterranean coast. One of these is a complete sequence of a 'half'ABCB, probably belonging to the ABCB10 subfamily, while the second is a 'full'ABCB1 transporter. A quantitative RT-PCR protocol for biomonitoring was tested in laboratory experiments. Bivalves exposed to diesel showed significant increase in B1 expression levels, while the expression of B10 was suppressed. These results suggest that B. pharaonis features an MDR1 homologue that is induced by pollution and may serve as a sentinel organism for routine biomonitoring programs. However, our findings also exemplify that not all MDRs are equally suitable for this purpose and sequence information must be expanded beyond the ATPase domain for correct classification of cloned genes.

  18. Preclinical validation of Aurora kinases-targeting drugs in osteosarcoma

    PubMed Central

    Tavanti, E; Sero, V; Vella, S; Fanelli, M; Michelacci, F; Landuzzi, L; Magagnoli, G; Versteeg, R; Picci, P; Hattinger, C M; Serra, M

    2013-01-01

    Background: Aurora kinases are key regulators of cell cycle and represent new promising therapeutic targets in several human tumours. Methods: Biological relevance of Aurora kinase-A and -B was assessed on osteosarcoma clinical samples and by silencing these genes with specific siRNA in three human osteosarcoma cell lines. In vitro efficacy of two Aurora kinases-targeting drugs (VX-680 and ZM447439) was evaluated on a panel of four drug-sensitive and six drug-resistant human osteosarcoma cell lines. Results: Human osteosarcoma cell lines proved to be highly sensitive to both drugs. A decreased drug sensitivity was observed in doxorubicin-resistant cell lines, most probably related to ABCB1/MDR1 overexpression. Both drugs variably induced hyperploidy and apoptosis in the majority of cell lines. VX-680 also reduced in vitro cell motility and soft-agar cloning efficiency. Drug association experiments showed that VX-680 positively interacts with all conventional drugs used in osteosarcoma chemotherapy, overcoming the cross-resistance observed in the single-drug treatments. Conclusion: Aurora kinase-A and -B represent new candidate therapeutic targets for osteosarcoma. In vitro analysis of the Aurora kinases inhibitors VX-680 and ZM447439 indicated in VX-680 a new promising drug of potential clinical usefulness in association with conventional osteosarcoma chemotherapeutic agents. PMID:24129234

  19. Modulation of the multidrug resistance P-glycoprotein: Detection with technetium-99m-sestamibi in vivo

    SciTech Connect

    Luker, G.D.; Fracasso, P.M.; Dobkin, J.; Piwnica-Worms, D.

    1997-03-01

    Overexpression of the multidrug resistance (MDR1) P-glycoprotein (Pgp) has been documented in nearly all forms of human cancers and increased levels of Pgp in some tumors correlate with poor response to treatment. Technetium-99m-sestamibi has recently been validated as a Pgp transport substrate. Pgp is also normally expressed along the biliary canalicular surface of hepatocytes and the luminal side of proximal tubule cells in the kidney, while not expressed in heart. Focused on these organs with known Pgp status, we present the findings on {sup 99m}Tc-sestamibi showed normal, prompt clearance of the radiotracer from the liver and kidneys relative to the heart. After administration of the Pgp modulator, {sup 99m}Tc-sestamibi was selectively retained in the liver and kidneys. Hepatobiliary and renal clearance of {sup 99m}Tc-sestamibi are Pgp-mediated, and inhibition of Pgp transport in these organs can be successfully imaged using {sup 99m}Tc-sestamibi in patients. Similar results might be expected with this and related radiopharmaceuticals for functional imaging of Pgp transport and modulation in tumors. 34 refs., 2 figs.

  20. Synthesis, molecular structure, and properties of a neutral Schiff base phenolic complex of magnesium

    SciTech Connect

    Polyakov, V.R.; Sharma, V.; Crankshaw, C.L.; Piwnica-Worms, D.

    1998-09-07

    Multidrug resistance (MDR) in cancer mediated by the MDR1 P-glycoprotein (Pgp), a 140--180 kDa plasma membrane protein, renders chemotherapeutic treatment ineffective by pumping a variety of natural product cytotoxic agents and xenobiotic compounds out of cancer cells. Pgp has been a major target for synthesis and development of both therapeutic antagonists that block its transport function and diagnostic radiopharmaceuticals that are transported by the protein for use in functional imaging of Pgp transport activity in tumors in vivo. Most, but not all, compounds that interact with Pgp are hydrophobic and cationic at physiological pH. To further understand the Pgp targeting properties, the authors sought to directly evaluate the effect of charge of the complex on Pgp interactions. This could be done by comparing the cytotoxicity profile of a neutral complex to that of an identical, but positively charged, complex in both drug-sensitive and multidrug-resistant cancer cells. Thus, a neutral analogue of the Ga(III) and Fe(III) complexes was desired. Herein the authors describe the synthesis and structure of a novel neutral Schiff base Mg complex and evaluate its cytotoxic potency in human drug-sensitive KB-3-1 and multi-drug-resistant KB-8-5 tumor cells.

  1. Asclepiasterol, a novel C21 steroidal glycoside derived from Asclepias curassavica, reverses tumor multidrug resistance by down-regulating P-glycoprotein expression

    PubMed Central

    Wang, Jun; Ma, Yan; Li, Wen-Xue; Jiang, Ren-Wang; Cai, Shao-Hui

    2016-01-01

    Multidrug resistance (MDR) mediated by P-glycoprotein (P-gp) is a major cause of cancer therapy failure. In this study, we identified a novel C21 steroidal glycoside, asclepiasterol, capable of reversing P-gp-mediated MDR. Asclepiasterol (2.5 and 5.0μM) enhanced the cytotoxity of P-gp substrate anticancer drugs in MCF-7/ADR and HepG-2/ADM cells. MDR cells were more responsive to paclitaxel in the presence of asclepiasterol, and colony formation of MDR cells was only reduced upon treatment with a combination of asclepiasterol and doxorubicin. Consistent with these findings, asclepiasterol treatment increased the intracellular accumulation of doxorubicin and rhodamine 123 (Rh123) in MDR cells. Asclepiasterol decreased expression of P-gp protein without stimulating or suppressing MDR1 mRNA levels. Asclepiasterol-mediated P-gp suppression caused inhibition of ERK1/2 phosphorylation in two MDR cell types, and EGF, an activator of the MAPK/ERK pathway, reversed the P-gp down-regulation, implicating the MAPK/ERK pathway in asclepiasterol-mediated P-gp down-regulation. These results suggest that asclepiasterol could be developed as a modulator for reversing P-gp-mediated MDR in P-gp-overexpressing cancer variants. PMID:27129170

  2. Human intestinal transporter database: QSAR modeling and virtual profiling of drug uptake, efflux and interactions

    PubMed Central

    Sedykh, Alexander; Fourches, Denis; Duan, Jianmin; Hucke, Oliver; Garneau, Michel; Zhu, Hao; Bonneau, Pierre; Tropsha, Alexander

    2013-01-01

    Purpose Membrane transporters mediate many biological effects of chemicals and play a major role in pharmacokinetics and drug resistance. The selection of viable drug candidates among biologically active compounds requires the assessment of their transporter interaction profiles. Methods Using public sources, we have assembled and curated the largest, to our knowledge, human intestinal transporter database (>5,000 interaction entries for >3,700 molecules). This data was used to develop thoroughly validated classification Quantitative Structure-Activity Relationship (QSAR) models of transport and/or inhibition of several major transporters including MDR1, BCRP, MRP1-4, PEPT1, ASBT, OATP2B1, OCT1, and MCT1. Results & Conclusions QSAR models have been developed with advanced machine learning techniques such as Support Vector Machines, Random Forest, and k Nearest Neighbors using Dragon and MOE chemical descriptors. These models afforded high external prediction accuracies of 71–100% estimated by 5-fold external validation, and showed hit retrieval rates with up to 20-fold enrichment in the virtual screening of DrugBank compounds. The compendium of predictive QSAR models developed in this study can be used for virtual profiling of drug candidates and/or environmental agents with the optimal transporter profiles. PMID:23269503

  3. Osthole shows the potential to overcome P-glycoprotein‑mediated multidrug resistance in human myelogenous leukemia K562/ADM cells by inhibiting the PI3K/Akt signaling pathway.

    PubMed

    Wang, Hong; Jia, Xiu-Hong; Chen, Jie-Ru; Wang, Jian-Yong; Li, You-Jie

    2016-06-01

    P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) has been reported to play a pivotal role in tumor chemotherapy failure. Study after study has illustrated that the phosphoinositide 3-kinase (PI3K)/Akt signaling cascade is involved in the MDR phenotype and is correlated with P-gp expression in many human malignancies. In the present study, osthole, an O-methylated coumarin, exhibited potent reversal capability of MDR in myelogenous leukemia K562/ADM cells. Simultaneously, the uptake and efflux of Rhodamine-123 (Rh-123) and the accumulation of doxorubicin assays combined with flow cytometric analysis suggested that osthole could increase intracellular drug accumulation. Furthermore, osthole decreased the expression of multidrug resistance gene 1 (MDR1) at both the mRNA and protein levels. Further experiments elucidated that osthole could suppress P-gp expression by inhibiting the PI3K/Akt signaling pathway which might be the main mechanism accounting for the reversal potential of osthole in the MDR in K562/ADM cells. In conclusion, osthole combats MDR and could be a promising candidate for the development of novel MDR reversal modulators. PMID:27109742

  4. Investigation of the Plasmodium falciparum food vacuole through inducible expression of the chloroquine resistance transporter (PfCRT).

    PubMed

    Ehlgen, Florian; Pham, James S; de Koning-Ward, Tania; Cowman, Alan F; Ralph, Stuart A

    2012-01-01

    Haemoglobin degradation during the erythrocytic life stages is the major function of the food vacuole (FV) of Plasmodium falciparum and the target of several anti-malarial drugs that interfere with this metabolic pathway, killing the parasite. Two multi-spanning food vacuole membrane proteins are known, the multidrug resistance protein 1 (PfMDR1) and Chloroquine Resistance Transporter (PfCRT). Both modulate resistance to drugs that act in the food vacuole. To investigate the formation and behaviour of the food vacuole membrane we have generated inducible GFP fusions of chloroquine sensitive and resistant forms of the PfCRT protein. The inducible expression system allowed us to follow newly-induced fusion proteins, and corroborated a previous report of a direct trafficking route from the ER/Golgi to the food vacuole membrane. These parasites also allowed the definition of a food vacuole compartment in ring stage parasites well before haemozoin crystals were apparent, as well as the elucidation of secondary PfCRT-labelled compartments adjacent to the food vacuole in late stage parasites. We demonstrated that in addition to previously demonstrated Brefeldin A sensitivity, the trafficking of PfCRT is disrupted by Dynasore, a non competitive inhibitor of dynamin-mediated vesicle formation. Chloroquine sensitivity was not altered in parasites over-expressing chloroquine resistant or sensitive forms of the PfCRT fused to GFP, suggesting that the PfCRT does not mediate chloroquine transport as a GFP fusion protein.

  5. Cisplatin Resistant Spheroids Model Clinically Relevant Survival Mechanisms in Ovarian Tumors

    PubMed Central

    Miller, Daniel H.; Medina, Jamie E.; Hamilton, Joshua W.; Messerli, Mark A.; Brodsky, Alexander S.

    2016-01-01

    The majority of ovarian tumors eventually recur in a drug resistant form. Using cisplatin sensitive and resistant cell lines assembled into 3D spheroids we profiled gene expression and identified candidate mechanisms and biological pathways associated with cisplatin resistance. OVCAR-8 human ovarian carcinoma cells were exposed to sub-lethal concentrations of cisplatin to create a matched cisplatin-resistant cell line, OVCAR-8R. Genome-wide gene expression profiling of sensitive and resistant ovarian cancer spheroids identified 3,331 significantly differentially expressed probesets coding for 3,139 distinct protein-coding genes (Fc >2, FDR < 0.05) (S2 Table). Despite significant expression changes in some transporters including MDR1, cisplatin resistance was not associated with differences in intracellular cisplatin concentration. Cisplatin resistant cells were significantly enriched for a mesenchymal gene expression signature. OVCAR-8R resistance derived gene sets were significantly more biased to patients with shorter survival. From the most differentially expressed genes, we derived a 17-gene expression signature that identifies ovarian cancer patients with shorter overall survival in three independent datasets. We propose that the use of cisplatin resistant cell lines in 3D spheroid models is a viable approach to gain insight into resistance mechanisms relevant to ovarian tumors in patients. Our data support the emerging concept that ovarian cancers can acquire drug resistance through an epithelial-to-mesenchymal transition. PMID:26986722

  6. Gene expression analysis by a competitive and differential PCR with antisense competitors.

    PubMed

    de Kant, E; Rochlitz, C F; Herrmann, R

    1994-11-01

    We report a sensitive method for the reproducible and accurate measurement of gene expression from small samples of RNA. This method is based on a combination of two PCR techniques: First, an endogenous reporter gene and the gene of interest are simultaneously amplified in one tube after random-primed reverse transcription (RT) of RNA (differential RT-PCR). Second, exogenous homologous fragments of both genes with artificially introduced mutations are added and coamplified in the same reaction (competitive PCR). The first-strand cDNA, and the mutated antisense homologues of the reporter as well as the target gene compete for their respective primers and are therefore amplified with equal efficiencies. After PCR, restriction enzyme digestion allows visualization of the quantitative differences between the four resulting reaction products. The ratios of products that competed during PCR provide the quantitative information. The initial amount of a specific cDNA can be calculated from any competitor/cDNA ratio of reliably measurable PCR product amounts. Extensive competitor titration to experimentally approach the equilibrium is therefore unnecessary. The differential counterpart of competitive and differential RT-PCR (CD-RT-PCR) allows expression of the levels in reference to a reporter gene. MDR1 expression was determined in tumor cells by CD-RT-PCR.

  7. Development of a Physiologically-Based Pharmacokinetic Model of the Rat Central Nervous System

    PubMed Central

    Badhan, Raj K. Singh; Chenel, Marylore; Penny, Jeffrey I.

    2014-01-01

    Central nervous system (CNS) drug disposition is dictated by a drug’s physicochemical properties and its ability to permeate physiological barriers. The blood–brain barrier (BBB), blood-cerebrospinal fluid barrier and centrally located drug transporter proteins influence drug disposition within the central nervous system. Attainment of adequate brain-to-plasma and cerebrospinal fluid-to-plasma partitioning is important in determining the efficacy of centrally acting therapeutics. We have developed a physiologically-based pharmacokinetic model of the rat CNS which incorporates brain interstitial fluid (ISF), choroidal epithelial and total cerebrospinal fluid (CSF) compartments and accurately predicts CNS pharmacokinetics. The model yielded reasonable predictions of unbound brain-to-plasma partition ratio (Kpuu,brain) and CSF:plasma ratio (CSF:Plasmau) using a series of in vitro permeability and unbound fraction parameters. When using in vitro permeability data obtained from L-mdr1a cells to estimate rat in vivo permeability, the model successfully predicted, to within 4-fold, Kpuu,brain and CSF:Plasmau for 81.5% of compounds simulated. The model presented allows for simultaneous simulation and analysis of both brain biophase and CSF to accurately predict CNS pharmacokinetics from preclinical drug parameters routinely available during discovery and development pathways. PMID:24647103

  8. Cholelithiasis and Nephrolithiasis in HIV-Positive Patients in the Era of Combination Antiretroviral Therapy

    PubMed Central

    Lin, Kuan-Yin; Liao, Sih-Han; Liu, Wen-Chun; Cheng, Aristine; Lin, Shu-Wen; Chang, Sui-Yuan; Tsai, Mao-Song; Kuo, Ching-Hua; Wu, Mon-Ro; Wang, Hsiu-Po; Hung, Chien-Ching; Chang, Shan-Chwen

    2015-01-01

    Objectives This study aimed to describe the epidemiology and risk factors of cholelithiasis and nephrolithiasis among HIV-positive patients in the era of combination antiretroviral therapy. Methods We retrospectively reviewed the medical records of HIV-positive patients who underwent routine abdominal sonography for chronic viral hepatitis, fatty liver, or elevated aminotransferases between January 2004 and January 2015. Therapeutic drug monitoring of plasma concentrations of atazanavir was performed and genetic polymorphisms, including UDP-glucuronosyltransferase (UGT) 1A1*28 and multidrug resistance gene 1 (MDR1) G2677T/A, were determined in a subgroup of patients who received ritonavir-boosted or unboosted atazanavir-containing combination antiretroviral therapy. Information on demographics, clinical characteristics, and laboratory testing were collected and analyzed. Results During the 11-year study period, 910 patients who underwent routine abdominal sonography were included for analysis. The patients were mostly male (96.9%) with a mean age of 42.2 years and mean body-mass index of 22.9 kg/m2 and 85.8% being on antiretroviral therapy. The anchor antiretroviral agents included non-nucleoside reverse-transcriptase inhibitors (49.3%), unboosted atazanavir (34.4%), ritonavir-boosted lopinavir (20.4%), and ritonavir-boosted atazanavir (5.5%). The overall prevalence of cholelithiasis and nephrolithiasis was 12.5% and 8.2%, respectively. Among 680 antiretroviral-experienced patients with both baseline and follow-up sonography, the crude incidence of cholelithiasis and nephrolithiasis was 4.3% and 3.7%, respectively. In multivariate analysis, the independent factors associated with incident cholelithiasis were exposure to ritonavir-boosted atazanavir for >2 years (adjusted odds ratio [AOR], 6.29; 95% confidence interval [CI], 1.12–35.16) and older age (AOR, 1.04; 95% CI, 1.00–1.09). The positive association between duration of exposure to ritonavir

  9. Targeted lipid based drug conjugates: a novel strategy for drug delivery.

    PubMed

    Vadlapudi, Aswani Dutt; Vadlapatla, Ramya Krishna; Kwatra, Deep; Earla, Ravinder; Samanta, Swapan K; Pal, Dhananjay; Mitra, Ashim K

    2012-09-15

    A majority of studies involving prodrugs are directed to overcome low bioavailability of the parent drug. The aim of this study is to increase the bioavailability of acyclovir (ACV) by designing a novel prodrug delivery system which is more lipophilic, and at the same time site specific. In this study, a lipid raft has been conjugated to the parent drug molecule to impart lipophilicity. Simultaneously a targeting moiety that can be recognized by a specific transporter/receptor in the cell membrane has also been tethered to the other terminal of lipid raft. Targeted lipid prodrugs i.e., biotin-ricinoleicacid-acyclovir (B-R-ACV) and biotin-12hydroxystearicacid-acyclovir (B-12HS-ACV) were synthesized with ricinoleicacid and 12hydroxystearicacid as the lipophilic rafts and biotin as the targeting moiety. Biotin-ACV (B-ACV), ricinoleicacid-ACV (R-ACV) and 12hydroxystearicacid-ACV (12HS-ACV) were also synthesized to delineate the individual effects of the targeting and the lipid moieties. Cellular accumulation studies were performed in confluent MDCK-MDR1 and Caco-2 cells. The targeted lipid prodrugs B-R-ACV and B-12HS-ACV exhibited much higher cellular accumulation than B-ACV, R-ACV and 12HS-ACV in both cell lines. This result indicates that both the targeting and the lipid moiety act synergistically toward cellular uptake. The biotin conjugated prodrugs caused a decrease in the uptake of [(3)H] biotin suggesting the role of sodium dependent multivitamin transporter (SMVT) in uptake. The affinity of these targeted lipid prodrugs toward SMVT was studied in MDCK-MDR1 cells. Both the targeted lipid prodrugs B-R-ACV (20.25 ± 1.74 μM) and B-12HS-ACV (23.99 ± 3.20 μM) demonstrated higher affinity towards SMVT than B-ACV (30.90 ± 4.19 μM). Further, dose dependent studies revealed a concentration dependent inhibitory effect on [(3)H] biotin uptake in the presence of biotinylated prodrugs. Transepithelial transport studies showed lowering of [(3)H] biotin permeability in