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Our previous study identified 52 antiplasmodial peptaibols isolated from fungi. To understand their antiplasmodial mechanism of action, we conducted phenotypic assays, assessed the in vitro evolution of resistance, and performed a transcriptome analysis of the most potent peptaibol, HZ NPDG-I. HZ NPDG-I and 2 additional peptaibols were compared for their killing action and stage dependency, each showing a loss of digestive vacuole (DV) content via ultrastructural analysis. HZ NPDG-I demonstrated a stepwise increase in DV pH, impaired DV membrane permeability, and the ability to form ion channels upon reconstitution in planar membranes. This compound showed no signs of cross resistance to targets of current clinical candidates, and 3 independent lines evolved to resist HZ NPDG-I acquired nonsynonymous changes in the P. falciparum multidrug resistance transporter, pfmdr1. Conditional knockdown of PfMDR1 showed varying effects to other peptaibol analogs, suggesting differing sensitivity.

Histone acetyltransferase inhibitors (HATi) are mechanism-based inhibitors that show promise in the treatment of several illnesses, including diabetes, hyperlipidemia, cancer, and Alzheimer's disease. The work emphasizes the significance of HATi as a possible treatment strategy against Candida species biofilms. Here, in this study, we found that combining a HATi, anacardic acid (AA), and quercetin, a known flavonoid, significantly prevented biofilm formation by C. tropicalis. We further show that C. tropicalis exhibited a considerable downregulation of drug-resistance gene expression (CDR1 and MDR1) when co-administrated. Additionally, in silico studies revealed that the AA interacts strongly with a histone acetyltransferase, Rtt109, which may account for the observed biofilm inhibitory effect. In conclusion, the study illustrates how HATi may be used to potentiate the inhibitory action of phytoactives or antifungals against drug-resistant yeast infections. [ABSTRACT FROM AUTHOR]

The space environment can affect the function of all physiological systems, including the properties of cell membranes. Our goal in this study was to explore the effect of simulated microgravity (SMG) on the cellular uptake of small molecules based on reported microgravity-induced changes in membrane properties. SMG was applied to cultured cells using a random-positioning machine for up to three hours. We assessed the cellular accumulation of compounds representing substrates of uptake and efflux transporters, and of compounds not shown to be transported by membrane carriers. Exposure to SMG led to an increase of up to 60% (p < 0.01) in the cellular uptake of efflux transporter substrates, whereas a glucose transporter substrate showed a decrease of 20% (p < 0.05). The uptake of the cathepsin activity-based probe GB123 (MW, 1198 g/mol) was also enhanced (1.3-fold, p < 0.05). Cellular emission of molecules larger than ~3000 g/mol was reduced by up to 50% in SMG (p < 0.05). Our findings suggest that short-term exposure to SMG could differentially affect drug distribution across membranes. Longer exposure to microgravity, e.g., during spaceflight, may have distinct effects on the cellular uptake of small molecules. [ABSTRACT FROM AUTHOR]

Introduction: Opportunistic fungi create biofilm resistant to active antifungal drugs in immunocompromised people. The present study aimed to assess the expression of CDR1 and MDR1 genes in the stages of biofilm formation by candidate species isolated from clinical samples. Material & Methods: 100 oral, vaginal, and fecal swabs were sampled from people with immune and physiological defects and normal people. The isolates were identified by laboratory tests and specific Candida chrome agar culture medium, and the presence of resistance genes was proved by molecular method. The formation of biofilm in the presence and absence of amphotericin B- in the strains was investigated using the crystal violet test and scanning electron microscope photo. The expression level of CDR1 and MDR1 genes was determined using the real-time polymerase chain reaction (PCR) technique. Results: More than 50% of isolated strains were Candida albicans, and the frequency of other strains was 8.33%. Among the 60 strains that were investigated in terms of genotype, only 48 Candida strains had both CDR1 and MDR1 genes. The statistical analysis of the results demonstrated that the amphotericin B-drug during 30 hours after biofilm formation significantly reduced the expression of resistance genes compared to the control group (P

Abstract Background The burden of malaria persists in sub-Saharan Africa and the emergence of artemisinin resistance has introduced complexity to control efforts. Monitoring the efficacy of artemisinin-based treatment for malaria is crucial to address this challenge. This study assessed treatment efficacy of artemether-lumefantrine (AL) and genetic diversity of Plasmodium falciparum isolates in a Nigerian population. Methods Participants presenting with clinical symptoms of uncomplicated malaria at a health centre in Lagos, Nigeria, were screened for P. falciparum. Enrolled participants were treated with AL and monitored through scheduled check-up visits, clinical and laboratory examinations for 28 days. Parasite clearance and genetic diversity were assessed through polymerase chain reaction (PCR) analysis of merozoite surface proteins (msp1 and msp2). The prevalence of drug resistance mutations was assessed by P. falciparum multidrug resistance gene 1 (mdr1) genotyping followed by P. falciparum ubiquitin-specific protease 1 (ubp1) gene sequencing. Results The PCR-uncorrected treatment outcome revealed 94.4% adequate clinical and parasitological response (ACPR) and 5.6% late parasitological failure (LPF) rates. After PCR correction, no suspected LPF case was detected and ACPR 67/67 (100%) was achieved in all the individuals. Moreover, a high prevalence of wild-type alleles for mdr1 N86Y (93.7%), and mdr1 D1246Y (87.5%) was observed. Genetic diversity analysis revealed predominant K1 allelic family for msp1 (90.2%) and FC27 for msp2 (64.4%). Estimated multiplicity of infection (MOI) was 1.7, with the highest MOI observed in the 5–15 years age group. ubp1 sequence analysis identified one nonsynonymous E1528D polymorphism at a low frequency (1.6%). Conclusion The study demonstrated sustained efficacy of AL for treating uncomplicated P. falciparum malaria. Genetic diversity analysis revealed various allelic types, suggesting occurrences of polyclonal infections. Nonetheless, the detection of a significant ubp1 polymorphism could have future implications for the epidemiology of anti-malarial drug resistance in the population.

Abstract Background The burden of chronic kidney disease (CKD) and kidney failure in Ghana is on the ascendency, with the prevalence of CKD estimated at 13.3%. Patients with CKD who progress to kidney failure require life sustaining kidney replacement therapy (KRT) which is almost exclusively available in Ghana as haemodialysis. Kidney transplantation is considered the best KRT option for patients with irreversible kidney failure due to its relative cost efficiency as well as its superiority in terms of survival and quality of life. However, because transplants may trigger an immune response with potential organ rejection, immunosuppressants such as tacrolimus dosing are required. Objective This study sought to determine single nucleotide polymorphisms in CYP3A5, CYP3A4 and MDR1 genes that affect the pharmacokinetics of Tacrolimus in a population of Ghanaian patients with kidney failure. Method This cross-sectional study comprised of 82 kidney failure patients undergoing maintenance haemodialysis at the Renal and Dialysis unit of Korle-Bu Teaching Hospital (KBTH). Clinical and demographic data were collected and genomic DNA isolated. Samples were genotyped for specific SNPs using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). Results Participants, 58/82 (70.73%) harbored the wildtype CYP3A5*1/*1 AA genotype, 20/82 (24.39%) carried the heterozygous CYP3A5*1/*3 AG genotype, and 4/82 (4.88%) had the homozygous mutant CYP3A5*3/*3 GG genotype. Also, 6/82 (7.32%) carried the wildtype AA genotype, 11/82 (13.41%) had the heterozygous AG genotype, and 65/82 (79.27%) harbored the homozygous mutant GG genotype of CYP3A4*1B (-290 A>G). For MDR1_Ex21 (2677 G>T), 81/82 (98.78%) carried the wildtype GG genotype, while 1/82 (1.22%) had the heterozygous GT genotype. For MDR1_Ex26 (3435 C>T), 63/82 (76.83%) had the wildtype CC genotype, while 18/82 (21.95%) carried the heterozygous CT genotype, and 1/82 (1.22%) harbored the mutant TT genotype. Conclusion SNPs in CYP3A4, CYP3A5, and MDR1 genes in a population of Ghanaian kidney failure patients were described. The varying SNPs of the featured genes suggest the need to consider the genetic status of Ghanaians kidney failure patients prior to transplantation and tacrolimus therapy.

Abstract Bictegravir, a key second-generation integrase strand transfer inhibitor in the treatment of HIV, is subject to active efflux transport mediated by ABCB1 (P-glycoprotein). Several coding variants of ABCB1 have been described and associated with variable effects on substrate drugs pharmacokinetics. Here, we investigated the effect of the four most common coding ABCB1 single nucleotide polymorphisms (i.e., c.1199G > A, c.1236C > T, c.2677G > T and c.3435C > T) on the intracellular accumulation of bictegravir. Using a previously validated HEK293 recombinant cell line model, we found decreased bictegravir intracellular concentrations in cell lines overexpressing ABCB1 as compared to control cell lines, in line with the known role of ABCB1 in bictegravir transport. However, we were unable to demonstrate any significant difference in bictegravir intracellular accumulation when comparing HEK293 cells overexpressing the wild type (1236C-2677G-3435C, 1199G) or the variant (1236C-2677G-3435T, 1236T-2677T-3435T or 1199A) proteins. These findings suggest that the ABCB1 c.1199G > A and c.1236C > T-c.2677G > T-c.3435C > T variants have no or at least limited impact on the active transport of bictegravir by ABCB1.

Background: The burden of malaria persists in sub-Saharan Africa and the emergence of artemisinin resistance has introduced complexity to control efforts. Monitoring the efficacy of artemisinin-based treatment for malaria is crucial to address this challenge. This study assessed treatment efficacy of artemether-lumefantrine (AL) and genetic diversity of Plasmodium falciparum isolates in a Nigerian population. Methods: Participants presenting with clinical symptoms of uncomplicated malaria at a health centre in Lagos, Nigeria, were screened for P. falciparum. Enrolled participants were treated with AL and monitored through scheduled check-up visits, clinical and laboratory examinations for 28 days. Parasite clearance and genetic diversity were assessed through polymerase chain reaction (PCR) analysis of merozoite surface proteins (msp1 and msp2). The prevalence of drug resistance mutations was assessed by P. falciparum multidrug resistance gene 1 (mdr1) genotyping followed by P. falciparum ubiquitin-specific protease 1 (ubp1) gene sequencing. Results: The PCR-uncorrected treatment outcome revealed 94.4% adequate clinical and parasitological response (ACPR) and 5.6% late parasitological failure (LPF) rates. After PCR correction, no suspected LPF case was detected and ACPR 67/67 (100%) was achieved in all the individuals. Moreover, a high prevalence of wild-type alleles for mdr1 N86Y (93.7%), and mdr1 D1246Y (87.5%) was observed. Genetic diversity analysis revealed predominant K1 allelic family for msp1 (90.2%) and FC27 for msp2 (64.4%). Estimated multiplicity of infection (MOI) was 1.7, with the highest MOI observed in the 5–15 years age group. ubp1 sequence analysis identified one nonsynonymous E1528D polymorphism at a low frequency (1.6%). Conclusion: The study demonstrated sustained efficacy of AL for treating uncomplicated P. falciparum malaria. Genetic diversity analysis revealed various allelic types, suggesting occurrences of polyclonal infections. Nonetheless, the detection of a significant ubp1 polymorphism could have future implications for the epidemiology of anti-malarial drug resistance in the population. [ABSTRACT FROM AUTHOR]

The relapses and refractory disease are a challenge in the management of patients with Takayasu arteritis (TAK). We quantified pathogenic CD4 + memory T helper cells bearing surface markers CD161 and/or p-glycoprotein (MDR1) in patients with TAK. Peripheral blood mononuclear cells of 21 patients with TAK and 16 age-matched controls were stained with anti-CD3, anti-CD4, anti-CD45RA, anti-CD161 and anti-p-glycoprotein antibodies and subjected to flow cytometry by FACS ARIAIII. Eighteen patients underwent follow-up immunophenotyping. Intracellular staining for interleukin-17 and interferon-γ was performed for 18 patients and 11 controls. Surgical arterial biopsies of 6 TAK and 5 non-inflammatory controls were subjected to immunohistochemistry with anti-CD161 and anti-p-glycoprotein. At baseline the frequency of MDR1 + CD4 + and CD161 + MDR1 + CD4 + memory T cells was higher in TAK than controls (p = 0.002 and 0.01, respectively). After stimulation, the frequency of IFN-y + CD161 + cells was higher in TAK than controls (p = 0.028). Modal fluorescence intensity of CD161 + MDR1 + CD45RA − CD4 + cells was higher in active as compared with stable disease (p = 0.041). At 6 months, MDR1 + and CD161 + MDR1 + memory CD4 + T cells decreased significantly only in patients who had complete/partial response to treatment (p = 0.047 and 0.02, respectively). To conclude, MDR1 + and MDR1 + CD161 + CD4 + memory T-helper cells are increased in patients with TAK. These cells decreased only in patients with response to treatment during subsequent follow-up. [ABSTRACT FROM AUTHOR]

Background: The burden of chronic kidney disease (CKD) and kidney failure in Ghana is on the ascendency, with the prevalence of CKD estimated at 13.3%. Patients with CKD who progress to kidney failure require life sustaining kidney replacement therapy (KRT) which is almost exclusively available in Ghana as haemodialysis. Kidney transplantation is considered the best KRT option for patients with irreversible kidney failure due to its relative cost efficiency as well as its superiority in terms of survival and quality of life. However, because transplants may trigger an immune response with potential organ rejection, immunosuppressants such as tacrolimus dosing are required. Objective: This study sought to determine single nucleotide polymorphisms in CYP3A5, CYP3A4 and MDR1 genes that affect the pharmacokinetics of Tacrolimus in a population of Ghanaian patients with kidney failure. Method: This cross-sectional study comprised of 82 kidney failure patients undergoing maintenance haemodialysis at the Renal and Dialysis unit of Korle-Bu Teaching Hospital (KBTH). Clinical and demographic data were collected and genomic DNA isolated. Samples were genotyped for specific SNPs using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). Results: Participants, 58/82 (70.73%) harbored the wildtype CYP3A5*1/*1 AA genotype, 20/82 (24.39%) carried the heterozygous CYP3A5*1/*3 AG genotype, and 4/82 (4.88%) had the homozygous mutant CYP3A5*3/*3 GG genotype. Also, 6/82 (7.32%) carried the wildtype AA genotype, 11/82 (13.41%) had the heterozygous AG genotype, and 65/82 (79.27%) harbored the homozygous mutant GG genotype of CYP3A4*1B (-290 A>G). For MDR1_Ex21 (2677 G>T), 81/82 (98.78%) carried the wildtype GG genotype, while 1/82 (1.22%) had the heterozygous GT genotype. For MDR1_Ex26 (3435 C>T), 63/82 (76.83%) had the wildtype CC genotype, while 18/82 (21.95%) carried the heterozygous CT genotype, and 1/82 (1.22%) harbored the mutant TT genotype. Conclusion: SNPs in CYP3A4, CYP3A5, and MDR1 genes in a population of Ghanaian kidney failure patients were described. The varying SNPs of the featured genes suggest the need to consider the genetic status of Ghanaians kidney failure patients prior to transplantation and tacrolimus therapy. [ABSTRACT FROM AUTHOR]

Bictegravir, a key second-generation integrase strand transfer inhibitor in the treatment of HIV, is subject to active efflux transport mediated by ABCB1 (P-glycoprotein). Several coding variants of ABCB1 have been described and associated with variable effects on substrate drugs pharmacokinetics. Here, we investigated the effect of the four most common coding ABCB1 single nucleotide polymorphisms (i.e., c.1199G > A, c.1236C > T, c.2677G > T and c.3435C > T) on the intracellular accumulation of bictegravir. Using a previously validated HEK293 recombinant cell line model, we found decreased bictegravir intracellular concentrations in cell lines overexpressing ABCB1 as compared to control cell lines, in line with the known role of ABCB1 in bictegravir transport. However, we were unable to demonstrate any significant difference in bictegravir intracellular accumulation when comparing HEK293 cells overexpressing the wild type (1236C-2677G-3435C, 1199G) or the variant (1236C-2677G-3435T, 1236T-2677T-3435T or 1199A) proteins. These findings suggest that the ABCB1 c.1199G > A and c.1236C > T-c.2677G > T-c.3435C > T variants have no or at least limited impact on the active transport of bictegravir by ABCB1. [ABSTRACT FROM AUTHOR]

Introduction: Opportunistic fungi create biofilm resistant to active antifungal drugs in immunocompromised people. The present study aimed to assess the expression of CDR1 and MDR1 genes in the stages of biofilm formation by candidate species isolated from clinical samples. Material & Methods: 100 oral, vaginal, and fecal swabs were sampled from people with immune and physiological defects and normal people. The isolates were identified by laboratory tests and specific Candida chrome agar culture medium, and the presence of resistance genes was proved by molecular method. The formation of biofilm in the presence and absence of amphotericin B- in the strains was investigated using the crystal violet test and scanning electron microscope photo. The expression level of CDR1 and MDR1 genes was determined using the real-time polymerase chain reaction (PCR) technique. Results: More than 50% of isolated strains were Candida albicans, and the frequency of other strains was 8.33%. Among the 60 strains that were investigated in terms of genotype, only 48 Candida strains had both CDR1 and MDR1 genes. The statistical analysis of the results demonstrated that the amphotericin B-drug during 30 hours after biofilm formation significantly reduced the expression of resistance genes compared to the control group (P<0.05). Discussion & Conclusion: The expression of resistance genes in Candida albicans and Candida tropicalis is effective in increasing biofilm formation and the occurrence of candidiasis. Simultaneous expression of resistance genes is effective in increasing Candida albicans pathogenicity. The sub-MIC concentration of amphotericin B significantly reduces the expression of resistance genes and biofilm formation in Candida strains. [ABSTRACT FROM AUTHOR]

Due to their high expression profile of multi‐drug resistance genes, cancer stem cells (CSCs) are the main source of drug resistance. The aim of this study was to establish a gemcitabine‐hydrochloride‐resistant (rt) human non‐small cell lung cancer (hNSCLC) cell line and their CSC line to be used as disease models in various cancer studies. In the first phase of study, a gemcitabine hydrochloride‐rt hNSCLC line cells was produced by making them rt through periodic exposure to gemcitabine hydrochloride. This acquired gemcitabine‐hydrochloride‐rt hNSCLC cell line was characterized for resistance. Subsequently, a CSC population with a CD326 + CD133 + CD44+ phenotypes was immunoselectively isolated from gemcitabine hydrochloride‐rt hNSCLCs purified from a single cell by colony forming technology. This rt CSC line was characterized for both resistance and stemness. Rt and non‐rt CSCs were analyzed and compared with each other in terms of immunophenotyping the expression profiles of ALDH1, CD90, ABCG2, CD44 and MDR1, which are CSC specific markers, of demonstrating mitotic capacity with growth curve analysis and of their ability to form tumor spheroids in three different 3D cultures. The results of this study demonstrated for the first time the successful generation of both gemcitabine‐hydrochloride‐rt hNSCLC cells and CSCs derived from gemcitabine‐hydrochloride‐rt hNSCLC cells. It was also shown that isolated and characterized rt CSCs could proliferate and form tumor spheres in vitro using three different 3D in vitro techniques. It was shown that the cell surface markers CD326, CD133 and CD44 can serve as an antibody panel for CSCs. Significance statement: This study aimed to establish gemcitabine‐hydrochloride‐resistant (rt) human non‐small cell lung cancer (hNSCLC) cells and their cancer stem cells (CSCs) for cancer research. Gemcitabine‐rt hNSCLC cells were generated through periodic exposure. A CD326 + CD133 + CD44 + CSC population was isolated from these rt cells. Comparative analysis of rt and non‐rt CSCs revealed significant differences in marker expression, mitotic capacity, and spheroid formation ability. This study demonstrated successful generation of both rt hNSCLC cells and their CSCs, highlighting the potential of CD326, CD133, and CD44 as CSC markers. [ABSTRACT FROM AUTHOR]

Implementing the 3R initiative to reduce animal experiments in brain penetration prediction for CNS-targeting drugs requires more predictive in vitro and in silico models. However, animal studies are still indispensable to obtaining brain concentration and determining the prediction performance of in vitro models. To reveal species differences and provide reliable data for IVIVE, in vitro models are required. Systems overexpressing MDR1 and BCRP are widely used to predict BBB penetration, highlighting the impact of the in vitro system on predictive performance. In this study, endogenous Abcb1 knock-out MDCKII cells overexpressing MDR1 of human, mouse, rat or cynomolgus monkey origin were used. Good correlations between ERs of 83 drugs determined in each cell line suggest limited species specificities. All cell lines differentiated CNS-penetrating compounds based on ERs with high efficiency and sensitivity. The correlation between in vivo and predicted Kp,uu,brain was the highest using total ER of human MDR1 and BCRP and optimized scaling factors. MDR1 interactors were tested on all MDR1 orthologs using digoxin and quinidine as substrates. We found several examples of inhibition dependent on either substrate or transporter abundance. In summary, this assay system has the potential for early-stage brain penetration screening. IC50 comparison between orthologs is complex; correlation with transporter abundance data is not necessarily proportional and requires the understanding of modes of transporter inhibition. [ABSTRACT FROM AUTHOR]

Objective: Chronic obstructive pulmonary disease (COPD) is described as partially reversible airflow limitation. P-glycoprotein (P-gp/MDR1), encoded by the Multidrug Resistance 1 (MDR1) gene, is regarded as a protective component for the respiratory tract and is present in tracheobronchial epithelium and lung parenchyma, and removes particles from cells and protects against various xenobiotics. Polymorphisms of MDR1 gene and the alteration in the expression of P-gp are considered to have a negative effect on the severity of COPD pathogenesis and treatment efficacy. We aimed to investigate the relationship of the MDR1 gene polymorphisms with reversibility in COPD patients. Materials and Methods: The MDR1 polymorphisms, specifically the 3435C>T and 2677A/G variations, were analyzed in 90 COPD patients. Results: 15 of the 90 COPD patients had positive reversibility tests. 2677TT (p=0.044) and 3435TT (p=0.003) alleles related to positive reversibility tests. There were no significant differences in the distribution of the MDR1 C3435 alleles and the G2677 alleles (p> 0.05). Conclusion: COPD patients with the TT allele have a higher rate of early reversibility positivity; this suggests that those carrying the allele may respond better to bronchodilator therapy. These markers could help to distinguish COPD patients who respond better to β2-agonists or who may not benefit much and, therefore, need different drugs. [ABSTRACT FROM AUTHOR]

The fungal pathogen Candida auris represents a severe threat to hospitalized patients. Its resistance to multiple classes of antifungal drugs and ability to spread and resist decontamination in healthcare settings make it especially dangerous. We screened 1,990 clinically approved and late-stage investigational compounds for the potential to be repurposed as antifungal drugs targeting C. auris and narrowed our focus to five Food and Drug Administration (FDA)-approved compounds with inhibitory concentrations under 10 µM for C. auris and significantly lower toxicity to three human cell lines. These compounds, some of which had been previously identified in independent screens, include three dihalogenated 8-hydroxyquinolines: broxyquinoline, chloroxine, and clioquinol. A subsequent structure-activity study of 32 quinoline derivatives found that 8-hydroxyquinolines, especially those dihalogenated at the C5 and C7 positions, were the most effective inhibitors of C. auris. To pursue these compounds further, we exposed C. auris to clioquinol in an extended experimental evolution study and found that C. auris developed only twofold to fivefold resistance to the compound. DNA sequencing of resistant strains and subsequent verification by directed mutation in naive strains revealed that resistance was due to mutations in the transcriptional regulator CAP1 (causing upregulation of the drug transporter MDR1) and in the drug transporter CDR1. These mutations had only modest effects on resistance to traditional antifungal agents, and the CDR1 mutation rendered C. auris more susceptible to posaconazole. This observation raises the possibility that a combination treatment involving an 8-hydroxyquinoline and posaconazole might prevent C. auris from developing resistance to this established antifungal agent. IMPORTANCE The rapidly emerging fungal pathogen Candida auris represents a growing threat to hospitalized patients, in part due to frequent resistance to multiple classes of antifungal drugs. We identify a class of compounds, the dihalogenated 8-hydroxyquinolines, with broad fungistatic ability against a diverse collection of 13 strains of C. auris. Although this compound has been identified in previous screens, we extended the analysis by showing that C. auris developed only modest twofold to fivefold increases in resistance to this class of compounds despite long-term exposure; a noticeable difference from the 30- to 500-fold increases in resistance reported for similar studies with commonly used antifungal drugs. We also identify the mutations underlying the resistance. These results suggest that the dihalogenated 8-hydroxyquinolines are working inside the fungal cell and should be developed further to combat C. auris and other fungal pathogens. Lohse and colleagues characterize a class of compounds that inhibit the fungal pathogen C. auris. Unlike many other antifungal drugs, C. auris does not readily develop resistance to this class of compounds.

Commensal enteric bacteria have evolved systems that enable growth in the ecologic niche of the host gastrointestinal tract. Animals evolved parallel mechanisms to survive the constant exposure to bacteria and their metabolic by-products. We propose that drug transporters encompass a crucial system to managing the gut microbiome. Drug transporters are present in the apical surface of gut epithelia. They detoxify cells from small molecules and toxins (xenobiotics) in the lumen. Here, we review what is known about commensal structure in the absence of the transporter ABCB1/P-glycoprotein in mammalian models. Knockout or low-activity alleles of ABCB1 lead to dysbiosis, Crohn's disease and ulcerative colitis in mammals. However, the exact function of ABCB1 in these contexts remain unclear. We highlight emerging models—the zebrafish Danio rerio and sea urchin Lytechinus pictus—that are poised to help dissect the fundamental mechanisms of ATP-binding cassette (ABC) transporters in the tolerance of commensal and pathogenic communities in the gut. We and others hypothesize that ABCB1 plays a direct role in exporting inflammatory bacterial products from host epithelia. Interdisciplinary work in this research area will lend novel insight to the transporter-mediated pathways that impact microbiome community structure and accelerate the pathogenesis of inflammatory bowel disease when perturbed. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'. [ABSTRACT FROM AUTHOR]

ATP-binding cassette (ABC) transporters play a crucial role for the efflux of a wide range of substrates across different cellular membranes. In the central nervous system (CNS), ABC transporters have recently gathered significant attention due to their pivotal involvement in brain physiology and neurodegenerative disorders, such as Alzheimer's disease (AD). Glial cells are fundamental for normal CNS function and engage with several ABC transporters in different ways. Here, we specifically highlight ABC transporters involved in the maintenance of brain homeostasis and their implications in its metabolic regulation. We also show new aspects related to ABC transporter function found in less recognized diseases, such as Huntington's disease (HD) and experimental autoimmune encephalomyelitis (EAE), as a model for multiple sclerosis (MS). Understanding both their impact on the physiological regulation of the CNS and their roles in brain diseases holds promise for uncovering new therapeutic options. Further investigations and preclinical studies are warranted to elucidate the complex interplay between glial ABC transporters and physiological brain functions, potentially leading to effective therapeutic interventions also for rare CNS disorders. [ABSTRACT FROM AUTHOR]

The feline MDR1 mutation (ABCB11930_1931delTC) has been associated with neurological toxicosis after topical application of eprinomectin products labeled for feline use. Information was collected from veterinarians who submitted samples for ABCB11930_1931delTC genotyping. In most cases, the submission form indicated an adverse event involving eprinomectin, in other cases submitting veterinarians were contacted to determine whether the patient had experienced an adverse drug event involving eprinomectin. If so, additional information was obtained to determine whether the case met inclusion criteria. 14 cases were highly consistent with eprinomectin toxicosis. Eight cats were homozygous for ABCB11930_1931del TC (3 died; 5 recovered). Six cats were homozygous wildtype (2 died; 4 recovered). The observed ABCB11930_1931delTC frequency (57%) was higher than the expected frequency (≤1%) in the feline population (Fisher Exact test, p < 0.01). Among wildtype cats, four were concurrently treated with potential competitive inhibitors of P‐glycoprotein. Results indicate that topical eprinomectin products, should be avoided in cats homozygous for ABCB11930_1931delTC. This is a serious, preventable adverse event occurring in an identifiable subpopulation treated with FDA‐approved products in accordance with label directions. Acquired P‐glycoprotein deficiency resulting from drug interactions may enhance susceptibility to eprinomectin‐induced neurological toxicosis in any cat, regardless of ABCB1 genotype. [ABSTRACT FROM AUTHOR]

Background: Drug resistance is one of the most critical problems in gastric cancer therapy. This study was performed to investigate the valproic acid effects on the proliferation of sensitive and resistant cell lines of human gastric cancer, and to explore the mechanism of the agent on multi drug resistance and apoptosis genes. Methods: The cytotoxicity effect of valproic acid on the EPG85.257 and EPG85.257RDB cells was assessed by the MTT assay, and the IC50 concentration was evaluated. Apoptosis, genotoxicity, and drug resistance pump activity were evaluated using comet assay, Real-time PCR, and flow cytometry, respectively. Cell proliferation was assayed using a scratch test. Results: Dose-dependent toxicity was recorded after treatment of cells with valproic acid. Valproic acid represented a significant growth inhibition on EPG85.257 cells with IC50 values of 5.84 µM and 4.78 µM after 48 h and 72 h treatment, respectively. In contrast, the drug-resistant counterpart represented 8.7 µM and 7.02 µM IC50 values after the same treatment time. Valproic acid induced PTEN, Bcl2, P53, Bax, P21, and caspase3 expression in EPG85.257 cells, whereas p21, p53, PTEN, and ABCB1 were overexpressed in EPG5.257RDB. Valproic acid hindered cell migration in both cell lines (P < 0.01). Valproate genotoxicity was significantly higher in the parent cells than in their resistant EPG85.257RDB counterparts. Valproate led to a 62% reduction in the daunorubicin efflux of the MDR1 pump activity. Conclusions: Valproate can affect drug resistance in gastric cancer via a unique mechanism independent of MDR1 expression. [ABSTRACT FROM AUTHOR]

The article focuses on investigating the mechanisms of bendamustine resistance in leukemia cells, emphasizing epigenetic factors, particularly the methylation status of the PLK-1 gene. It is reported that Bendamustine-resistant leukemia cells exhibited decreased expression of Polo-like kinase-1 (PLK-1) mRNA. It is noted that treatment with the demethylating agent 5-aza-2'-deoxycytidine significantly increased PLK-1 gene expression.

Background: Cutaneous leishmaniasis is among the neglected diseases in the world. Pentavalent antimonial compounds are considered the first-line treatment for this disease. However, using alternative natural products has received great attention due to the side effects of chemical drugs and drug resistance of the Leishmania parasite. The present study aims to investigate the effect of Satureja khuzestanica essential oil (SKEO) on MDR1 gene expression. Methods: In this study, standard strains of Leishmania major promastigotes were exposed to 5, 10, 15, and 20 µg/ml of SKEO. MDR1 gene expression of parasites exposed to essential oil was evaluated using real-time PCR. GAPDH was employed as the housekeeping gene for internal control. Results: Despite the increase, no statistically significant difference was observed in the relative expression of the MDR1 gene between the control group and the groups containing 5, 10, and 20 µg/ml of SKEO (P > 0.05). The relative expression of the MDR1 gene significantly increased in the group containing 15 μg/ml of essential oil compared to the control one (P < 0.05). Conclusion: This study showed that the use of essential oil of Satureja khuzestanica plant can have an increasing effect on the expression of MDR1 gene of Leishmania promastigotes, which is the best case if Satureja khuzestanica essential oil reduces the expression of MDR1 gene. So it seems that the use of essential oil of Satoria plant is effective in controlling Leishmania parasite, but its concentrations induce drug resistance. As a result, concentrations of essential oil should be used that have a controlling effect on the growth and proliferation of Leishmania parasite and also have the least effect on the induction of MDR1 gene expression. [ABSTRACT FROM AUTHOR]

Abstract Background Gemcitabine is a cornerstone drug for the treatment of all stages of pancreatic cancer and can prolong the survival of patients with pancreatic cancer, but resistance to gemcitabine in pancreatic cancer patients hinders its efficacy. The overexpression of Early growth response 1(EGR1) in pancreatic ductal adenocarcinoma as a mechanism of gemcitabine chemoresistance in pancreatic cancer has not been explored. The major mechanisms of gemcitabine chemoresistance are related to drug uptake, metabolism, and action. One of the common causes of tumor multidrug resistance (MDR) to chemotherapy in cancer cells is that transporter proteins increase intracellular drug efflux and decrease drug concentrations by inducing anti-apoptotic mechanisms. It has been reported that gemcitabine binds to MDR1 with high affinity. The purpose of this research was to investigate the potential mechanisms by which EGR1 associates with MDR1 to regulate gemcitabine resistance in pancreatic cancer cells. Methods The following in vitro and in vivo techniques were used in this research to explore the potential mechanisms by which EGR1 binds to MDR1 to regulate gemcitabine resistance in pancreatic cancer cells. Cell culture; in vitro and in vivo study of EGR1 function by loss of function analysis. Binding of EGR1 to the MDR1 promoter was detected using the ChIP assay. qRT-PCR, Western blot assays to detect protein and mRNA expression; use of Annexin V apoptosis detection assay to test apoptosis; CCK8, Edu assay to test cell proliferation viability. The animal model of pancreatic cancer subcutaneous allograft was constructed and the tumours were stained with hematoxylin eosin and Ki-67 expression was detected using immunohistochemistry. Findings We revealed that EGR1 expression was increased in different pancreatic cancer cell lines compared to normal pancreatic ductal epithelial cells. Moreover, gemcitabine treatment induced upregulation of EGR1 expression in a dose- and time-dependent manner. EGR1 is significantly enriched in the MDR1 promoter sequence.Upon knockdown of EGR1, cell proliferation was impaired in CFPAC-1 and PANC-1 cell lines, apoptosis was enhanced and MDR1 expression was decreased, thereby partially reversing gemcitabine chemoresistance. In animal experiments, knockdown of EGR1 enhanced the inhibitory effect of gemcitabine on tumor growth compared with the sh-NC group. Conclusions Our study suggests that EGR1 may be involved in the regulation of MDR1 to enhance gemcitabine resistance in pancreatic cancer cells. EGR1 could be a novel therapeutic target to overcome gemcitabine resistance in pancreatic cancer.

The space environment can affect the function of all physiological systems, including the properties of cell membranes. Our goal in this study was to explore the effect of simulated microgravity (SMG) on the cellular uptake of small molecules based on reported microgravity-induced changes in membrane properties. SMG was applied to cultured cells using a random-positioning machine for up to three hours. We assessed the cellular accumulation of compounds representing substrates of uptake and efflux transporters, and of compounds not shown to be transported by membrane carriers. Exposure to SMG led to an increase of up to 60% (p < 0.01) in the cellular uptake of efflux transporter substrates, whereas a glucose transporter substrate showed a decrease of 20% (p < 0.05). The uptake of the cathepsin activity-based probe GB123 (MW, 1198 g/mol) was also enhanced (1.3-fold, p < 0.05). Cellular emission of molecules larger than ~3000 g/mol was reduced by up to 50% in SMG (p < 0.05). Our findings suggest that short-term exposure to SMG could differentially affect drug distribution across membranes. Longer exposure to microgravity, e.g., during spaceflight, may have distinct effects on the cellular uptake of small molecules.

Background: Gemcitabine is a cornerstone drug for the treatment of all stages of pancreatic cancer and can prolong the survival of patients with pancreatic cancer, but resistance to gemcitabine in pancreatic cancer patients hinders its efficacy. The overexpression of Early growth response 1(EGR1) in pancreatic ductal adenocarcinoma as a mechanism of gemcitabine chemoresistance in pancreatic cancer has not been explored. The major mechanisms of gemcitabine chemoresistance are related to drug uptake, metabolism, and action. One of the common causes of tumor multidrug resistance (MDR) to chemotherapy in cancer cells is that transporter proteins increase intracellular drug efflux and decrease drug concentrations by inducing anti-apoptotic mechanisms. It has been reported that gemcitabine binds to MDR1 with high affinity. The purpose of this research was to investigate the potential mechanisms by which EGR1 associates with MDR1 to regulate gemcitabine resistance in pancreatic cancer cells. Methods: The following in vitro and in vivo techniques were used in this research to explore the potential mechanisms by which EGR1 binds to MDR1 to regulate gemcitabine resistance in pancreatic cancer cells. Cell culture; in vitro and in vivo study of EGR1 function by loss of function analysis. Binding of EGR1 to the MDR1 promoter was detected using the ChIP assay. qRT-PCR, Western blot assays to detect protein and mRNA expression; use of Annexin V apoptosis detection assay to test apoptosis; CCK8, Edu assay to test cell proliferation viability. The animal model of pancreatic cancer subcutaneous allograft was constructed and the tumours were stained with hematoxylin eosin and Ki-67 expression was detected using immunohistochemistry. Findings: We revealed that EGR1 expression was increased in different pancreatic cancer cell lines compared to normal pancreatic ductal epithelial cells. Moreover, gemcitabine treatment induced upregulation of EGR1 expression in a dose- and time-dependent manner. EGR1 is significantly enriched in the MDR1 promoter sequence.Upon knockdown of EGR1, cell proliferation was impaired in CFPAC-1 and PANC-1 cell lines, apoptosis was enhanced and MDR1 expression was decreased, thereby partially reversing gemcitabine chemoresistance. In animal experiments, knockdown of EGR1 enhanced the inhibitory effect of gemcitabine on tumor growth compared with the sh-NC group. Conclusions: Our study suggests that EGR1 may be involved in the regulation of MDR1 to enhance gemcitabine resistance in pancreatic cancer cells. EGR1 could be a novel therapeutic target to overcome gemcitabine resistance in pancreatic cancer. [ABSTRACT FROM AUTHOR]

Tadalafil, a phosphodiesterase 5 (PDE5) inhibitor, is a candidate therapeutic agent for fetal growth restriction and hypertensive disorders of pregnancy. In this study, we elucidated the fetal transfer of tadalafil in comparison with that of sildenafil, the first PDE5 inhibitor to be approved. We also examined the contributions of multidrug resistance protein 1 (MDR1) and breast cancer resistance protein (BCRP) to fetal transfer. Tadalafil or sildenafil was administered to wild-type, Mdr1a/b-double-knockout or Bcrp-knockout pregnant mice by continuous infusion from gestational day (GD) 14.5 to 17.5, and the fetal-to-maternal plasma concentration ratio of unbound drug (unbound F/M ratio) was evaluated at GD 17.5. The values of unbound F/M ratio of tadalafil and sildenafil in wild-type mice were 0.80 and 1.6, respectively. The unbound F/M ratio of tadalafil was increased to 1.1 and 1.7 in Mdr1a/b-knockout and Bcrp-knockout mice, respectively, while the corresponding values for sildenafil were equal to or less than that in wild-type mice, respectively. A transcellular transport study revealed that basal-to-apical transport of both tadalafil and sildenafil was significantly higher than transport in the opposite direction in MDCKII-BCRP cells. Our research reveals that tadalafil is a newly identified substrate of human and mouse BCRP, and it appears that the fetal transfer of tadalafil is, at least in part, attributed to the involvement of BCRP within the placental processes in mice. The transfer of sildenafil to the fetus was not significantly constrained by BCRP, even though sildenafil was indeed a substantial substrate for BCRP. [Display omitted] [ABSTRACT FROM AUTHOR]

Objective: Several strategies for preventing toxicity and resistance to taxane-based chemotherapy have been investigated so far. Lately, findings on the genetic variants associated with neutropenia and neuropathy (N&N) toxicity have been reported. Patients and Methods: A panel assay of single nucleotide polymorphisms (SNP) related to paclitaxel and Docetaxel toxicity on four candidate genes ATP-binding cassette subfamily B member 1 (ABCB1), Beta-tubulin 2A (TUBB2A), Cytochrome P450 3A4* 1B (CYP3A4*1B), Excision-Repair Cross-Complementing group 2 (ERCC3) are validated and discussed. We genotyped 37 cancer patients who received paclitaxel or docetaxel-based therapy. Furthermore, an early outline evaluation of the genotyping costs and benefits was assessed. Results: A total of 37 patients were treated with a taxane of which 17 (45.9%) had adverse N&N events. Pharmacogenomics analysis showed no relation between candidate gene polymorphisms and toxicity, except for the ERCC3 AG+GG allele [OR 2.61 (95% CI: 0.91–7.61)] that showed a significantly weak trend of risk of neurotoxicities vs. the AG allele [OR 1.52 (95% CI: 0.51–4.91)] p=0.03. Conclusions: We propose a useful genotyping panel assay to prevent toxicity in patients undergoing taxane-based therapy at an affordable price, with help from the literature and our experimental results and data. Based on the individual pharmacogenomics profile, clinicians will have additional information to personalize the treatment for the patient to minimize toxicity and maximize benefits, and they can also determine the cost-effectiveness for national healthcare sustainability.

ABSTRACTZinc cluster transcription factors (Zcfs) encoding zcf genes are exclusive for fungi and required for multiple cellular processes including metabolism and development. Genome-wide screening of 228 zinc cluster transcription factor encoding genes by overexpression in Aspergillus fumigatus revealed 11 genes which provided increased tolerance to the broadly applied azole voriconazole or to the polyene amphotericin B or to both. These include four oxidative stress and drug resistance genes (odrA-D) genes encoding factors, which provide broad cellular stress protection. Thereby, the corresponding fungal OdrA/Mdu2- and AtrR/OdrD-dependent genetic networks are interconnected. OdrA/Mdu2 activates atrR/odrD transcription by direct binding to the promoter, whereas AtrR/OdrD functions as repressor of odrA/mdu2 expression. odrA/mdu2 overexpression provides combined resistance to amphotericin B, voriconazole, itraconazole, and reactive oxygen species generated by menadione. OdrA/Mdu2-mediated itraconazole resistance is evoked by direct regulation of the transporter encoding gene mdr1. Oxidative stress-inducing substances like amphotericin B and menadione promote OdrA/Mdu2 accumulation in the nucleus to regulate stress response genes like mdr1 and the putative glutathione-S-transferase encoding gene gstD. The expression levels and external stress conditions fostering nuclear accumulation of OdrA/Mdu2 determine the regulation of the target genes. Hence, OdrA/Mdu2 provides a combined adaptation strategy for survival in nature or within a potential host, where this fungus represents the most common agent for human mold pneumonia worldwide. The OdrA/Mdu2 controlled genetic network highlights the tight connection between oxidative stress response and antifungal drug adaption to secure A. fumigatus survival in various hostile environments.IMPORTANCEAn overexpression screen of 228 zinc cluster transcription factor encoding genes of A. fumigatus revealed 11 genes conferring increased tolerance to antifungal drugs. Out of these, four oxidative stress and drug tolerance transcription factor encoding odr genes increased tolerance to oxidative stress and antifungal drugs when overexpressed. This supports a correlation between oxidative stress response and antifungal drug tolerance in A. fumigatus. OdrA/Mdu2 is required for the cross-tolerance between azoles, polyenes, and oxidative stress and activates genes for detoxification. Under oxidative stress conditions or when overexpressed, OdrA/Mdu2 accumulates in the nucleus and activates detoxifying genes by direct binding at their promoters, as we describe with the mdr1 gene encoding an itraconazole specific efflux pump. Finally, this work gives new insights about drug and stress resistance in the opportunistic pathogenic fungus A. fumigatus.

Nearly 50 ATP-binding cassette (ABC) transporters are encoded by mammalian genomes. These transporters are characterized by conserved nucleotidebinding and hydrolysis (i.e., ATPase) domains, and power directional transport of diverse substrate classes – ions, small molecule metabolites, xenobiotics, hydrophobic drugs, and even polypeptides – into or out of cells or subcellular organelles. Although immunological functions of ABC transporters are only beginning to be unraveled, emerging literature suggests these proteins have under-appreciated roles in the development and function of T lymphocytes, including many of the key effector, memory and regulatory subsets that arise during responses to infection, inflammation or cancers. One transporter in particular, MDR1 (Multidrug resistance-1; encoded by the ABCB1 locus in humans), has taken center stage as a novel player in immune regulation. Although MDR1 remains widely viewed as a simple drug efflux pump in tumor cells, recent evidence suggests that this transporter fills key endogenous roles in enforcing metabolic fitness of activated CD4 and CD8 T cells. Here, we summarize current understanding of the physiological functions of ABC transporters in immune regulation, with a focus on the anti-oxidant functions of MDR1 that may shape both the magnitude and repertoires of antigen-specific effector and memory T cell compartments. While much remains to be learned about the functions of ABC transporters in immunobiology, it is already clear that they represent fertile new ground, both for the definition of novel immunometabolic pathways, and for the discovery of new drug targets that could be leveraged to optimize immune responses to vaccines and cancer immunotherapies. [ABSTRACT FROM AUTHOR]

Abstract Multidrug resistance (MDR) is a primary limitation of breast cancer chemotherapy. The common mechanism of MDR is various anticancer drugs can be effluxed by the cell membrane protein P‐glycoprotein (P‐gp). Here, we found that ectopic overexpression of Shc3 was detected specifically in drug‐resistant breast cancer cells, consequently reducing sensitivity to chemotherapy and promoting cell migration by mediating P‐gp expression. However, the molecular mechanism underlying the interplay between P‐gp and Shc3 in breast cancer is unknown. We reported an additional resistance mechanism involving an increase in the active form of P‐gp after Shc3 upregulation. MCF‐7/ADR and SK‐BR‐3 cells can be sensitive to doxorubicin after knockdown of Shc3. Our results indicated that the interaction between ErbB2 and EphA2 is indirect and regulated by Shc3, and also, this complex is essential for activation of the MAPK and AKT pathways. Meanwhile, Shc3 promotes ErbB2 nuclear translocation, followed by a subsequent increase of the COX2 expression through ErbB2 binding to the COX2 promoter. We further demonstrated that COX2 expression was positively correlated with P‐gp expression and the Shc3/ErbB2/COX2 axis upregulates P‐gp activity in vivo. Our results show the crucial roles of Shc3 and ErbB2 in modulating P‐gp efficacy in breast cancer cells and suggest that Shc3 inhibition may enhance the sensitivity to chemotherapeutic drugs that target oncogene addiction pathways.

Objective To investigate the expression and significance of progesterone X receptor (PXR), multidrug resistant protein 1 (MDR1), cytochrome P450 3A5 (CYP3A5), and cytochrome P450 2B6 (CYP2B6) in high-grade serous ovarian cancer (HGSOC). Methods A total of 56 patients with HGSOC admitted to the Department of Gynecology, Qingdao Municipal Hospital from September 2019 to December 2021 were included in the experimental group. The patients were further divided into drug resistant group (24 cases) and sensitive group (32 cases) according to their resistance to platinum chemotherapy drugs. The control group included 16 patients with uterine fibroids admitted during the same period. The expression of PXR, MDR1, CYP3A5, and CYP2B6 in HGSOC and normal fallopian tubes were determined by immunohistochemistry, real-time quantitative PCR, and Western blotting. Results Compared with the control group, the positive expression rates of PXR, MDR1, CYP3A5, and CYP2B6 were significantly increased in the experimental group (χ2=12.879-17.174,P0.05). Conclusion PXR, MDR1, CYP3A5, and CYP2B6 are highly expressed in HGSOC, which may be involved in its occurrence and development. The detection of PXR, MDR1, CYP3A5, and CYP2B6 expression can be used to determine the sensitivity of HGSOC to chemotherapy, which is helpful to provide guidance for postoperative chemotherapy.

Implementing the 3R initiative to reduce animal experiments in brain penetration prediction for CNS-targeting drugs requires more predictive in vitro and in silico models. However, animal studies are still indispensable to obtaining brain concentration and determining the prediction performance of in vitro models. To reveal species differences and provide reliable data for IVIVE, in vitro models are required. Systems overexpressing MDR1 and BCRP are widely used to predict BBB penetration, highlighting the impact of the in vitro system on predictive performance. In this study, endogenous Abcb1 knock-out MDCKII cells overexpressing MDR1 of human, mouse, rat or cynomolgus monkey origin were used. Good correlations between ERs of 83 drugs determined in each cell line suggest limited species specificities. All cell lines differentiated CNS-penetrating compounds based on ERs with high efficiency and sensitivity. The correlation between in vivo and predicted Kp,uu,brain was the highest using total ER of human MDR1 and BCRP and optimized scaling factors. MDR1 interactors were tested on all MDR1 orthologs using digoxin and quinidine as substrates. We found several examples of inhibition dependent on either substrate or transporter abundance. In summary, this assay system has the potential for early-stage brain penetration screening. IC50 comparison between orthologs is complex; correlation with transporter abundance data is not necessarily proportional and requires the understanding of modes of transporter inhibition.

ATP-binding cassette (ABC) transporters play a crucial role for the efflux of a wide range of substrates across different cellular membranes. In the central nervous system (CNS), ABC transporters have recently gathered significant attention due to their pivotal involvement in brain physiology and neurodegenerative disorders, such as Alzheimer’s disease (AD). Glial cells are fundamental for normal CNS function and engage with several ABC transporters in different ways. Here, we specifically highlight ABC transporters involved in the maintenance of brain homeostasis and their implications in its metabolic regulation. We also show new aspects related to ABC transporter function found in less recognized diseases, such as Huntington’s disease (HD) and experimental autoimmune encephalomyelitis (EAE), as a model for multiple sclerosis (MS). Understanding both their impact on the physiological regulation of the CNS and their roles in brain diseases holds promise for uncovering new therapeutic options. Further investigations and preclinical studies are warranted to elucidate the complex interplay between glial ABC transporters and physiological brain functions, potentially leading to effective therapeutic interventions also for rare CNS disorders.

Nearly 50 ATP-binding cassette (ABC) transporters are encoded by mammalian genomes. These transporters are characterized by conserved nucleotide-binding and hydrolysis (i.e., ATPase) domains, and power directional transport of diverse substrate classes – ions, small molecule metabolites, xenobiotics, hydrophobic drugs, and even polypeptides – into or out of cells or subcellular organelles. Although immunological functions of ABC transporters are only beginning to be unraveled, emerging literature suggests these proteins have under-appreciated roles in the development and function of T lymphocytes, including many of the key effector, memory and regulatory subsets that arise during responses to infection, inflammation or cancers. One transporter in particular, MDR1 (Multidrug resistance-1; encoded by the ABCB1 locus in humans), has taken center stage as a novel player in immune regulation. Although MDR1 remains widely viewed as a simple drug efflux pump in tumor cells, recent evidence suggests that this transporter fills key endogenous roles in enforcing metabolic fitness of activated CD4 and CD8 T cells. Here, we summarize current understanding of the physiological functions of ABC transporters in immune regulation, with a focus on the anti-oxidant functions of MDR1 that may shape both the magnitude and repertoires of antigen-specific effector and memory T cell compartments. While much remains to be learned about the functions of ABC transporters in immunobiology, it is already clear that they represent fertile new ground, both for the definition of novel immunometabolic pathways, and for the discovery of new drug targets that could be leveraged to optimize immune responses to vaccines and cancer immunotherapies.

Antitumor immune evasion is a hallmark for the development and progression of cancer. Tumor cells adopt various mechanisms to escape the host immune system recognition. One such mechanism is the over expression of programmed death ligand (PD-L1), a negative T cell regulatory molecule. Because PD-L1 overexpression causes resistance to chemotherapeutic response in many cancers, herein we explored the relationship between PD-L1 and multidrug resistance protein MDR1 in breast cancer. Immunohistochemical evaluation of PD-L1 and MDR1 proteins in 194 breast cancer tissue samples were carried out. The relationship between PD-L1 and MDR1 expression on cancer cells with clinicopathological factors and prognosis was investigated. IHC showed a significant correlation between PD-L1 and MDR1 expression on tumor cells. Increased PD-L1 expression was also associated with lymph node status and tumor grade of the patient. Our results also revealed that the expression of PD-L1 and MDR1 was higher in TNBC subtype compared to other breast cancer subtypes. Therefore, a better understanding of the molecular mechanism through which PD-1/PD-L1 pathway contribute to the chemoresistance might bring forth the prognostic significance of PD-L1 and selection of patients who may benefit from immunotherapy. [ABSTRACT FROM AUTHOR]

The P‐glycoprotein (P‐gp) substrate status of antineoplastic drugs intended for veterinary patients is an important characteristic to define for two reasons. First, neoplastic cells expressing P‐gp can actively efflux drugs that are P‐gp substrates curtailing their efficacy. Second, antineoplastic drugs tend to have a narrow therapeutic index. Antineoplastic drugs that are P‐gp substrates can cause severe adverse reactions in animals with P‐gp dysfunction such as dogs with ABCB1‐1Δ and cats with ABCB11930_1931del TC. Animals with P‐gp dysfunction experience greater overall exposure to P‐gp substrate drugs due to mechanisms such as increased intestinal absorption, decreased biliary clearance and greater central nervous system penetration compared with animals with normal P‐gp function. Accordingly, knowing the P‐gp substrate status of antineoplastic drugs is an important safety consideration prior to use in canine or feline cancer patients. This study used a cell line overexpressing canine P‐gp to assess the P‐gp substrate status of verdinexor. Based on both a cytotoxicity assay and a competitive flow cytometry assay verdinexor is not a substrate for canine P‐gp. [ABSTRACT FROM AUTHOR]

Concern about the global emergence of multidrug-resistant fungal pathogens led us to explore the use of combination therapy to combat azole resistance in Candida auris. Clorgyline had previously been shown to be a multi-target inhibitor of Cdr1 and Mdr1 efflux pumps of Candida albicans and Candida glabrata. A screen for antifungal sensitizers among synthetic analogs of Clorgyline detected interactions with the C. auris efflux pump azole substrates Posaconazole and Voriconazole. Of six Clorgyline analogs, M19 and M25 were identified as potential sensitizers of azole resistance. M19 and M25 were found to act synergistically with azoles against resistant C. auris clade I isolates and recombinant Saccharomyces cerevisiae strains overexpressing C. auris efflux pumps. Nile Red assays with the recombinant strains showed M19 and M25 inhibited the activity of Cdr1 and Mdr1 efflux pumps that are known to play key roles in azole resistance in C. auris clades I, III, and IV. While Clorgyline, M19 and M25 uncoupled the Oligomycin-sensitive ATPase activity of Cdr1 from C. albicans and C. auris, their mode of action is yet to be fully elucidated. The experimental combinations described herein provides a starting point to combat azole resistance dominated by overexpression of CauCdr1 in C. auris clades I and IV and CauMdr1 in C. auris clade III. [ABSTRACT FROM AUTHOR]

Neuromeningeal cryptococcosis is a life-threatening infection of the central nervous system, caused by encapsulated yeast belonging to the Cryptococcus neoformans and Cryptococcus gattii species complexes. Recent data showed that virulence and antifungal resistance are variable for yeasts belonging to the C. gattii species complex. There is an increase in resistance to fluconazole for yeasts of the C. gattii species complex and the virulence is variable according to the genotype. In the present study, (i) we explored and compared the mechanisms of resistance to fluconazole between C. deuterogattii clinically resistant strains and induced fluconazole-resistant strains by exposure to fluconazole in vitro, and (ii) we studied their virulence in the Galleria mellonella study model. We demonstrated that the fluconazole resistance mechanisms involved were different between clinically resistant strains and induced resistant strains. We also demonstrated that fluconazole-induced resistant strains are less virulent when compared to the original susceptible strains. On the contrary, the clinically resistant strain tested maintains its virulence compared to fluconazole-susceptible strains of the same sequence type. [ABSTRACT FROM AUTHOR]

Background Resistance to antiepileptic drugs (AEDs) remains one of the main challenges to neurologists. Polymorphisms of drug efflux transporters such as multidrug resistance (MDR1) gene and target sites such as the nucleus accumbens–associated 1 (NAC1) gene have been suggested to influence the responsiveness to treatment. Aim Evaluation of the association of MDR1 and NAC1 polymorphisms with AEDs resistance among Jordanian epileptic patients. Subjects and methods 86 Jordanian epileptics were included in the study. DNA was extracted and genotyping was conducted by polymerase chain reaction followed by sequencing. Nine single nucleotide polymorphisms (SNPs) on the MDR1 gene and six SNPs on the NAC1 gene were investigated. Results MDR1 and NAC1 polymorphisms don’t seem to influence the resistance to AEDs at the genotype or allele level. However, a strong association was found between MDR1 rs2032588 (OR = 5; 95%CI = [1.3–18.8], p = 0.01) and AEDs resistance among males at the allele level. Also, data revealed an association between MDR1 rs1128503 and AEDs resistance among females at the allele level. Conclusion The data suggest that MDR1 and NAC1 polymorphisms do not influence the AEDs resistance among Jordanian epileptics. However, there is a gender-dependent association between MDR1 polymorphisms and resistance to AEDs at two SNPs (rs2032588 and rs1128503).

Candida fungi are common opportunistic microorganisms capable of causing infections of various localization, as well as life-threatening conditions in immunocompromised patients, such as HIV-infected individuals, oncology patients, subjects undergoing HSCT, which number has been steadily increasing in recent years. In addition, resistance to anti-fungal drugs has been spreading as well. Naturally sensitive to azoles, C. albicans possess a variety of mechanisms of acquired resistance, including efflux transporters and target protein-encoding gene amplification. This study was conducted to assess a prevalence of such mechanisms in the isolates sample obtained from HIV-infected patients in the Moscow region of the Russian Federation, characterize a relationship between these mechanisms and patterns of developing drug resistance. 18 strains of C. albicans resistant to fluconazole and voriconazole were isolated from HIV-infected patients with recurrent oropharyngeal candidiasis in the Moscow region. The expression levels of the ERG11, MDR1, CDR1, CDR2 genes involved in the formation of acquired azole resistance were measured using quantitative PCR, the 2CT method with ACT and PMA genes as control genes and reference values of sensitive isolates. Expression levels exceeding the average values of sensitive isolates by more than 3 standard deviations were considered significantly elevated. In most of the isolates, elevated levels of CDR1 and CDR2 gene expression were found: 89% and 78%, respectively. The expression level of the MDR1 gene was increased only in 28% of cases. ERG11 expression levels were significantly elevated in 78% of the isolates. Expression levels of all resistance genes studied were significantly increased in 4 strains. In this sample of C. albicans isolates, acquired resistance is mainly associated with efflux vectors encoded by the CDR1 and CDR2 genes. Also, in most isolates, an increased expression level for the azole target protein gene ERG11 was detected. The expression level of the efflux transporter gene MDR1 was increased in the smallest number of samples. It is also impossible to exclude a potential role of other mechanisms in developing acquired resistance, such as mutations in the ERG11 gene. It can be assumed that the identified mechanisms of resistance result from long-term, widespread, and sometimes uncontrolled use of azoles, including those in treatment and prevention of candidiasis in HIV-infected patients.

Abstract Background The development of multidrug resistance (MDR) associated with the overexpression of the efflux transporters Mdr1 and Cdr1 in Candida species impedes antifungal therapies. The urgent need for novel agents able to inhibit the function of both pumps, led us to evaluate this property in 137 extracts obtained from Argentinian plants. Methods The ability of the extracts to reverse efflux pump-mediated MDR was determined with an agar chemosensitization assay using fluconazole (FCZ) resistant Mdr1- and Cdr1-overexpressing clinical isolates of Candida albicans and Candida glabrata as well as Saccharomyces cerevisiae strains selectively expressing Mdr1 (AD/CaMDR1) or Cdr1 (AD/CaCDR1). The resistance-reversing activity of the most potent extracts was further confirmed using a Nile Red accumulation assay. Results Fifteen plant extracts overcame the FCZ resistance of Candida albicans 1114, which overexpresses CaMdr1 and CaCdr1, and AD/CaMDR1, with those from Acalypha communis and Solanum atriplicifolium being the most effective showing 4- to 16-fold reversal of resistance at concentrations ≥ 25 µg/mL. Both extracts, and to a lesser extent that from Pterocaulon alopecuroides, also restored FCZ sensitivity in CgCdr1-overexpressing C. glabrata 109 and in AD/CaCDR1 with fold reversal values ranging from 4 to 32 and therefore demonstrating a dual effect against Mdr1 and Cdr1. Both, A. communis and S. atriplicifolium extracts at concentrations ≥ 12.5 and ≥ 25 µg/mL, respectively, increased the intracellular Nile Red accumulation in all yeast strains overexpressing efflux pumps. Conclusions The non-toxic and highly active extracts from A. communis and S. atripicifolium, provide promising sources of compounds for potentiating the antifungal effect of FCZ by blocking the efflux function of Mdr1 and Cdr1 transporters.

Acquired chemoresistance during chemotherapy, often accompanied by cross- and multi-resistance, limits therapeutic outcomes and leads to recurrence. In order to create in vitro model systems to understand acquired doxorubicin-resistance, we generated doxorubicin-resistant sublines of canine prostate adenocarcinoma and urothelial cell carcinoma cell lines. Chemoresistance to doxorubicin, cross-resistance to carboplatin, and the reversibility of the acquired resistance by the specific MDR1-inhibitor tariquidar were quantified in metabolic assays. Resistance mechanisms were characterized by expression of the efflux transporters MDR1 and RALBP1, as well as the molecular target of doxorubicin, TOP2A, with qPCR and Western blotting. Six out of nine cell lines established stable resistance to 2 µM doxorubicin. Drug efflux via massive MDR1 overexpression was identified as common, driving resistance mechanism in all sublines. MDR1 inhibition with tariquidar extensively reduced or reversed the acquired, and also partly the parental resistance. Three cell lines developed additional, non-MDR1-dependent resistance. RALBP1 was upregulated in one resistant subline at the protein level, while TOP2A expression was not altered. Combination therapies aiming to inhibit MDR1 activity can now be screened for synergistic effects using our resistant sublines. Nevertheless, detailed resistance mechanisms and maintained molecular target expression in the resistant sublines are still to be examined. [ABSTRACT FROM AUTHOR]

Multidrug resistance (MDR) is a primary limitation of breast cancer chemotherapy. The common mechanism of MDR is various anticancer drugs can be effluxed by the cell membrane protein P‐glycoprotein (P‐gp). Here, we found that ectopic overexpression of Shc3 was detected specifically in drug‐resistant breast cancer cells, consequently reducing sensitivity to chemotherapy and promoting cell migration by mediating P‐gp expression. However, the molecular mechanism underlying the interplay between P‐gp and Shc3 in breast cancer is unknown. We reported an additional resistance mechanism involving an increase in the active form of P‐gp after Shc3 upregulation. MCF‐7/ADR and SK‐BR‐3 cells can be sensitive to doxorubicin after knockdown of Shc3. Our results indicated that the interaction between ErbB2 and EphA2 is indirect and regulated by Shc3, and also, this complex is essential for activation of the MAPK and AKT pathways. Meanwhile, Shc3 promotes ErbB2 nuclear translocation, followed by a subsequent increase of the COX2 expression through ErbB2 binding to the COX2 promoter. We further demonstrated that COX2 expression was positively correlated with P‐gp expression and the Shc3/ErbB2/COX2 axis upregulates P‐gp activity in vivo. Our results show the crucial roles of Shc3 and ErbB2 in modulating P‐gp efficacy in breast cancer cells and suggest that Shc3 inhibition may enhance the sensitivity to chemotherapeutic drugs that target oncogene addiction pathways. [ABSTRACT FROM AUTHOR]

Background: The pathogenesis of inflammatory bowel disease may be associated with the disruption in interactions between the immune system and gut flora. Epigenetic mechanisms especially, DNA methylation appear to be significant regarding the interaction between the environment and genome. ABCB1 is the encoding gene for multi-drug resistance protein 1 (MDR1) (P-glycoprotein), which is an important transmembrane protein responsible for the efflux of cellular molecules from the intestinal wall to the lumen. Method: In this study, we compared the methylation status of the promoter of ABCB1 in rectal mucosa of patients with ulcerative colitis (UC) and healthy controls by using the bisulfite conversion system and real-time quantitative multiplex methylation-specific PCR (QM-MSP). Results: We demonstrated that the mucosal specimen of 26 UC patients had significantly higher levels of promoter methylation in comparison to 26 controls. Conclusion: As the first investigation of Iranian patients with UC, we showed that patients had higher levels of ABCB1 promoter methylation in their inflammatory rectal mucosa compared to controls. However, this altered state of methylation did not associate with the characteristics of the patients such as age and sex. Our findings are a basis for further studies on concurrent assessment of promoter methylation and expression of ABCB1 in UC. [ABSTRACT FROM AUTHOR]