scholarly journals Efflux Pump-Mediated Intrinsic Drug Resistance in Mycobacterium smegmatis

2004 ◽  
Vol 48 (7) ◽  
pp. 2415-2423 ◽  
Author(s):  
Xian-Zhi Li ◽  
Li Zhang ◽  
Hiroshi Nikaido
Keyword(s):  
Drug Resistance ◽  
Ethidium Bromide ◽  
Mycobacterium Smegmatis ◽  
Efflux Pump ◽  
Upstream Region ◽  
Drug Efflux ◽  
Intact Cells ◽  
Intrinsic Drug Resistance ◽  
Multiple Drugs ◽  
Increased Susceptibility

ABSTRACT The Mycobacterium smegmatis genome contains many genes encoding putative drug efflux pumps. Yet with the exception of lfrA, it is not clear whether these genes contribute to the intrinsic drug resistance of this organism. We showed first by reverse transcription (RT)-PCR that several of these genes, including lfrA as well as the homologues of Mycobacterium tuberculosis Rv1145, Rv1146, Rv1877, Rv2846c (efpA), and Rv3065 (mmr and emrE), were expressed at detectable levels in the strain mc2155. Null mutants each carrying an in-frame deletion of these genes were then constructed in M. smegmatis. The deletions of the lfrA gene or mmr homologue rendered the mutant more susceptible to multiple drugs such as fluoroquinolones, ethidium bromide, and acriflavine (two- to eightfold decrease in MICs). The deletion of the efpA homologue also produced increased susceptibility to these agents but unexpectedly also resulted in decreased susceptibility to rifamycins, isoniazid, and chloramphenicol (two- to fourfold increase in MICs). Deletion of the Rv1877 homologue produced some increased susceptibility to ethidium bromide, acriflavine, and erythromycin. The upstream region of lfrA contained a gene encoding a putative TetR family transcriptional repressor, dubbed LfrR. The deletion of lfrR elevated the expression of lfrA and produced higher resistance to multiple drugs. Multidrug-resistant single-step mutants, independent of LfrA and attributed to a yet-unidentified drug efflux pump (here called LfrX), were selected in vitro and showed decreased accumulation of norfloxacin, ethidium bromide, and acriflavine in intact cells. Finally, use of isogenic β-lactamase-deficient strains showed the contribution of LfrA and LfrX to resistance to certain β-lactams in M. smegmatis.

P-glycoprotein drug efflux pump involved in the mechanisms of intrinsic drug resistance in various colon cancer cell lines

1991 ◽  
Vol 41 (3) ◽  
pp. 349-359 ◽  
Author(s):  
Ellen C. Spoelstra ◽  
Henk Dekker ◽  
Gerrit Jan Schuurhuis ◽  
Henricus J. Broxterman ◽  
Jan Lankelma
Keyword(s):  
Colon Cancer ◽  
Drug Resistance ◽  
Cell Lines ◽  
Efflux Pump ◽  
Colon Cancer Cell ◽  
Drug Efflux ◽  
P Glycoprotein ◽  
Colon Cancer Cell Lines ◽  
Intrinsic Drug Resistance ◽  
Drug Efflux Pump

Clinical relevance of transmembrane drug efflux as a mechanism of multidrug resistance.

1998 ◽  
Vol 16 (11) ◽  
pp. 3674-3690 ◽  
Author(s):  
D M Bradshaw ◽  
R J Arceci
Keyword(s):  
Drug Resistance ◽  
Cell Death ◽  
Multidrug Resistance ◽  
Programmed Cell Death ◽  
Tumor Cells ◽  
Efflux Pump ◽  
Active Form ◽  
Cytotoxic Agents ◽  
Transport Systems ◽  
Drug Efflux

For cytotoxic agents to have an effect on tumor cells, drugs must first be transported into the cell, potentially be metabolized to an active form, and interact appropriately with target molecules. A final common pathway of cytotoxic agents is usually the initiation of programmed cell death, or apoptosis. Tumor cells overcome the effects of cytotoxic agents at one or more of these levels. The classic multidrug-resistance (MDR) phenotype, as mediated by the drug efflux pump, P-glycoprotein, is one of the most extensively studied mechanisms of drug resistance. Additional drug transporters, such as the multidrug resistance-associated proteins (MRPs), have also been identified and can convey drug-resistance phenotypes. Important questions remain as to how and whether such transport systems can be specifically measured and effectively targeted to improve therapeutic outcomes. Furthermore, alterations in drug targets, drug metabolism, repair of DNA damage caused by drugs, and the inability to initiate programmed cell death can all contribute to drug resistance and must be ultimately considered in the explanation of tumor-cell resistance to therapy. Continued exploration of the pharmacologic methods to circumvent drug resistance, as well as strategies that involve targeted therapy and immunomodulation, should increase the specificity and efficacy of treatments for patients with cancer.

Rab27B enhances drug resistance in hepatocellular carcinoma by promoting exosome-mediated drug efflux

2020 ◽  
Vol 41 (11) ◽  
pp. 1583-1591 ◽  
Author(s):  
Rui Li ◽  
Chengyong Dong ◽  
Keqiu Jiang ◽  
Rui Sun ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Liver Cancer ◽  
Therapeutic Effect ◽  
Efflux Pump ◽  
Human Life ◽  
Therapeutic Effects ◽  
Drug Efflux ◽  
Glycoprotein P ◽  
Chemotherapy Drugs ◽  
Underlying Mechanisms

Abstract Liver cancer is a major threat to human life and health, and chemotherapy has been the standard non-surgical treatment for liver cancer. However, the emergence of drug resistance of liver cancer cells has hindered the therapeutic effect of chemical drugs. The discovery of exosomes has provided new insights into the mechanisms underlying tumour cell resistance. In this study, we aimed to determine the proteins associated with drug resistance in tumour cells and to elucidate the underlying mechanisms. We found that Rab27B expression in drug (5-fluorouracil, 5Fu)-resistant Bel7402 (Bel/5Fu) cells increased significantly compared with that in drug-sensitive Bel7402 cells. In addition, Bel/5Fu cells secreted more exosomes under 5Fu stimulation. The number of exosomes secreted by Bel/5Fu cells significantly reduced after knocking down Rab27B, and the cellular concentration of 5Fu increased, enhancing its therapeutic effect. We also found that the administration of classical drug efflux pump (P-glycoprotein, P-gp) inhibitors together with knockdown of Rab27B further improved the therapeutic effects of chemotherapy drugs. In conclusion, our findings suggest that Rab27B could be a new therapeutic target in liver cancer.

scholarly journals Identification of residues in ABCG2 affecting protein trafficking and drug transport, using co-evolutionary analysis of ABCG sequences

2015 ◽  
Vol 35 (4) ◽  
Author(s):  
Ameena J. Haider ◽  
Megan H. Cox ◽  
Natalie Jones ◽  
Alice J. Goode ◽  
Katherine S. Bridge ◽  
...  
Keyword(s):  
Amino Acids ◽  
Drug Resistance ◽  
Protein Trafficking ◽  
Drug Transport ◽  
Protein Targeting ◽  
Efflux Pump ◽  
Efflux Pumps ◽  
Drug Efflux ◽  
Evolutionary Analysis ◽  
Drug Efflux Pump

Determining how efflux pumps function is important to understanding their role in drug resistance. We have identified amino acids in a human drug efflux pump that affect interaction with substrate and protein targeting.

scholarly journals Characterization of AreABC, an RND-type efflux system involved in antimicrobial resistance of Aliarcobacter butzleri

2021 ◽  
Author(s):  
Susana Ferreira ◽  
Ana L. Silva ◽  
Joana Tomás ◽  
Cristiana Mateus ◽  
Fernanda Domingues ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Efflux Pump ◽  
Stop Codon ◽  
Premature Stop Codon ◽  
Efflux System ◽  
Erythromycin Resistance ◽  
Efflux Pump Inhibitor ◽  
Underlying Mechanisms ◽  
Multiple Drugs ◽  
Increased Susceptibility

Aliarcobacter butzleri is an emergent enteropathogen for which resistance to several classes of antimicrobial agents has been described, although the underlying mechanisms have been poorly addressed. We aimed to evaluate the contribution of the resistance-nodulation-division-type (RND) efflux system, AreABC, to drug resistance in A. butzleri . A. butzleri strains were first tested against several antimicrobials, with and without an efflux pump inhibitor. Then, erythromycin resistant strains were screened for the presence of a premature stop codon in a putative transcriptional regulator of the AreABC system, areR . Lastly, antimicrobial susceptibility and ethidium bromide (EtBr) accumulation were evaluated using an areB -knockout strain and a strain overexpressing the AreABC system through areR truncation. The presence of the efflux pump inhibitor resulted in increased susceptibility to most of the antimicrobials tested. A correlation between erythromycin resistance and the presence of premature stop codons in areR was observed. The truncation of areR resulted in increased expression of the AreABC system and decreased susceptibility to various antimicrobials. In contrast, areB inactivation resulted in increased susceptibility and a higher intracellular accumulation of EtBr. In conclusion, the AreABC efflux pump plays a role in the resistance of A. butzleri to multiple drugs and is regulated by a putative transcriptional repressor areR . Our results support the importance of efflux pumps in this bacterium's resistance to major classes of antibiotics and other antimicrobials.

Differential Expression of Resistant and Efflux Pump Genes in MDR-TB Isolates

2020 ◽  
Vol 20 (2) ◽  
pp. 271-287 ◽  
Author(s):  
Manaf AlMatar ◽  
Işıl Var ◽  
Begüm Kayar ◽  
Fatih Köksal
Keyword(s):  
Drug Resistance ◽  
Target Genes ◽  
Efflux Pump ◽  
Gene Mutations ◽  
Clinical Isolates ◽  
Pomegranate Juice ◽  
Drug Efflux ◽  
Mdr Tb ◽  
Drug Efflux Pump

Background: Numerous investigations demonstrate efflux as a worldwide bacterial mode of action which contributes to the resistance of drugs. The activity of antibiotics, which subjects to efflux, can be improved by the combined usage of efflux inhibitors. However, the efflux role to the overall levels of antibiotic resistance of clinical M. tuberculosis isolates is inadequately comprehended and is still disregarded by many. Method: Here, we assessed the contribution of resistant genes associated with isoniazid (INH) and rifampin (R) resistance to the levels of drug resistance in the (27) clinical isolates of MDR-TB. Additionally, the role of the resistance for six putative drug efflux pump genes to the antibiotics was investigated. The level of katG expression was down-regulated in 24/27 (88.88%) of MDR-TB isolates. Of the 27 MDR-TB isolates, inhA, oxyR-ahpC, and rpoB showed either overexpression or up-regulation in 8 (29.62%), 4 (14.81 %), and 24 (88.88%), respectively. Moreover, the efflux pump genes drrA, drrB, efpA, Rv2459, Rv1634, and Rv1250 were overexpressed under INH/RIF plus fresh pomegranate juice (FPJ) stress signifying the efflux pumps contribution to the overall levels of the resistance of MDR-TB isolates. Conclusion: These results displayed that the levels of drug resistance of MDR-TB clinical isolates are due to combination among drug efflux pump and the presence of mutations in target genes, a truth which is often ignored by the specialists of tuberculosis in favour of the almost undoubted significance of drug target- gene mutations for the resistance in M. tuberculosis.

scholarly journals Characterization of the Mycobacterial MSMEG-3762/63 Efflux Pump in Mycobacterium smegmatis Drug Efflux

2020 ◽  
Vol 11 ◽  
Author(s):  
Barbara De Siena ◽  
Nicoletta Campolattano ◽  
Gianluca D’Abrosca ◽  
Luigi Russo ◽  
Daire Cantillon ◽  
...  
Keyword(s):  
Mycobacterium Smegmatis ◽  
Nitrosative Stress ◽  
Efflux Pump ◽  
Drug Efflux ◽  
Drug Resistant ◽  
Antimicrobial Drugs ◽  
Bioinformatics Analyses ◽  
Major Health Problem ◽  
Mdr Tb ◽  
Biofilm Development

Multi-drug resistant tuberculosis (MDR-TB) represents a major health problem worldwide. Drug efflux and the activity of efflux transporters likely play important roles in the development of drug-tolerant and drug-resistant mycobacterial phenotypes. This study is focused on the action of a mycobacterial efflux pump as a mechanism of drug resistance. Previous studies demonstrated up-regulation of the TetR-like transcriptional regulator MSMEG_3765 in Mycobacterium smegmatis and its ortholog Rv1685c in Mycobacterium tuberculosis (Mtb) in acid-nitrosative stress conditions. MSMEG-3765 regulates the expression of the MSMEG_3762/63/65 operon, and of the orthologous region in Mtb (Rv1687c/86c/85c). MSMEG-3762 and Rv1687c are annotated as ATP-binding proteins, while MSMEG-3763 and Rv1686c are annotated as trans-membrane polypeptides, defining an ABC efflux pump in both M. smegmatis and Mtb. The two putative efflux systems share a high percentage of identity. To examine the role of the putative efflux system MSMEG-3762/63, we constructed and characterized a MSMEG-3763 deletion mutant in M. smegmatis (∆MSMEG_3763). By comparative analysis of wild type, knockout, and complemented strains, together with structural modeling and molecular docking bioinformatics analyses of the MSMEG-3763 trans-membrane protein, we define the protein complex MSMEG-3762/63 as an efflux pump. Moreover, we demonstrate involvement of this pump in biofilm development and in the extrusion of rifampicin and ciprofloxacin (CIP), antimicrobial drugs used in first- and second-line anti-TB therapies.

The plant alkaloid piperine as a potential inhibitor of ethidium bromide efflux in Mycobacterium smegmatis

2011 ◽  
Vol 60 (2) ◽  
pp. 223-229 ◽  
Author(s):  
Jing Jin ◽  
Jiyu Zhang ◽  
Na Guo ◽  
Haihua Feng ◽  
Lei Li ◽  
...  
Keyword(s):  
Ethidium Bromide ◽  
Mycobacterium Smegmatis ◽  
Efflux Pump ◽  
Black Pepper ◽  
Piper Nigrum ◽  
Fluorometric Method ◽  
Piper Longum ◽  
Carbonyl Cyanide ◽  
Inhibition Ability ◽  
Positive Controls

Piperine, a major plant alkaloid found in black pepper (Piper nigrum) and long pepper (Piper longum), has shown potential for inhibiting the efflux pump (EP) of Staphylococcus aureus. In this study, a modulation assay showed that piperine could decrease the MIC of ethidium bromide (EtBr) twofold at 32 μg ml−1 and fourfold at 64 μg ml−1 against Mycobacterium smegmatis mc2 155 ATCC 700084. A real-time, 96-well plate fluorometric method was employed to evaluate the EP inhibition ability of piperine in M. smegmatis. Reserpine, chlorpromazine, verapamil and carbonyl cyanide m-chlorophenylhydrazone were used as positive controls. Piperine significantly enhanced accumulation and decreased the efflux of EtBr in M. smegmatis, which suggests that it has the ability to inhibit mycobacterial EPs.

scholarly journals Characterization of P55, a Multidrug Efflux Pump inMycobacterium bovis and Mycobacterium tuberculosis

2001 ◽  
Vol 45 (3) ◽  
pp. 800-804 ◽  
Author(s):  
Pedro E. A. Silva ◽  
Fabiana Bigi ◽  
Marı́a de la Paz Santangelo ◽  
Maria Isabel Romano ◽  
Carlos Martı́n ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mycobacterium Smegmatis ◽  
Efflux Pump ◽  
Tetracycline Resistance ◽  
Drug Efflux ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Reading Frame ◽  
Carbonyl Cyanide

ABSTRACT The Mycobacterium bovis P55 gene, located downstream from the gene that encodes the immunogenic lipoprotein P27, has been characterized. The gene was identical to the open reading frame of the Rv1410c gene in the genome of Mycobacterium tuberculosisH37Rv, annotated as a probable drug efflux protein. Genes similar toP55 were present in all species of the M. tuberculosis complex and other mycobacteria such asMycobacterium leprae and Mycobacterium avium. By Western blotting, P55 was located in the membrane fraction ofM. bovis. When transformed into Mycobacterium smegmatis after cloning, P55 conferred aminoglycoside and tetracycline resistance. The levels of resistance to streptomycin and tetracycline conferred by P55 were decreased in the presence of the protonophore carbonyl cyanide m-chlorophenylhydrazone and the pump inhibitors verapamil and reserpine. M. smegmatiscells expressing the plasmid-encoded P55 accumulated less tetracycline than the control cells. We conclude that P55 is a membrane protein implicated in aminoglycoside and tetracycline efflux in mycobacteria.

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