Protein Mrp Research Articles

Evaluating the Dynamics of Cyp3a11, MRP2 and MDR1 Modulation by IL-22

Background: IL-22 is a cytokine produced by a number of immune cell populations, including type 3 innate lymphoid cells. We have shown previously that IL-22 suppresses the expression Cyp3a11 in the mouse intestine, a gene that encodes a drug metabolizing. In addition, IL-22 reduces the expression of MRP2 and MDR1, the gene that encodes as Multidrug resistance protein 2 or 1 involve in the drug detoxification. Modulation of these proteins can influence the oral bioavailability of drugs. Aims: The aim of this study was to define the existence of reversible modulation of IL-22 on Cyp3a11, MRP2 and MDR1 expression and protein level or activity in the intestinal epithelium. Methods: In vitro enteroids of the mouse small intestine were cultured in 3D in the presence/absence of IL-22 for 5 days. Cyp3a11, MRP2 and MDR1 transcript expression was evaluated by qPCR followed by protein analysis to define their modulation and activity at varying timepoints after IL-22 treatment cessation. Results: IL-22 reduced the expression and activity of Cyp3a11 which normalized soon after stopping IL-22 treatment. This action of IL-22 are made without any modulation of protein level of Cyp3a11. In the same way, IL-22 reduces the expression and the protein level of MRP2 and MDR1, an effect normalizes after treatment cessation. Conclusions: IL-22 suppresses the expression and the activity of Cyp3a11 without any modulation of the protein level unlike at the level of MRP2 and MDR1 which are reduced. These data suggest that regulation of gene expression, protein or enzyme activity by IL-22 may have variable effects: Cyp3a11 is ATP-independent, whereas MRP2 and MDR1 are ATP-dependent. This direct or indirect enzymatic modulation of these proteins must be taken into account when assessing the role of the drug in the biology of the intestinal mucosa. Dr. Lloyd Sutherland Chair in IBD/GI Research/Weston Foundation. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

ABCC2 p.R393W variant contributes to Dubin-Johnson syndrome by targeting MRP2 to proteasome degradation

BackgroundDubin-Johnson syndrome (DJS), a rare autosomal recessive liver condition, is caused by biallelic loss-of-function mutations of the ABCC2 gene. This study aimed to investigate genetic variations in the drug efflux...

Ethanol Induces Blood Brain Barrier Dysfunction in Healthy and Familial Alzheimer’s Blood Brain Barrier Models

Background/Objective:
 The blood brain barrier (BBB) is a highly selective semipermeable membrane between the blood and brain. Active efflux transporters such as PGP, MRP-1, and BCRP and localized tight junction proteins ensure barrier integrity. Interestingly, both alcohol consumption and Alzheimer’s disease (AD) suppress barrier functions independently. Furthermore, alcohol use can lead to or worsened neurodegenerative disorders, including AD. In this study, human stem-cell derived healthy and AD BBB models with near in vivo properties are used to investigate the effects of alcohol on critical BBB properties such as barrier tightness and efflux transporter activity.
 Methods:
 Induced pluripotent stem cells (iPSCs) from healthy (IMR90) and Familial Alzheimer’s (APP, PSEN1, PSEN2) cell lines were differentiated into brain microvascular endothelial cells (BMECs). BMECs were treated with varying ethanol concentrations (5, 25, 50, and 100 mM) for one hour. Following ethanol treatment several barrier properties were assessed: trans-endothelial electrical resistance (TEER), sodium fluorescein permeability, tight junction localization, and efflux transporter activity.
 Results:
 Moderate to severe ethanol concentrations (25 mM and 50 mM) reduced TEER and delocalized tight junctions in healthy and AD-derived BMECs, indicating a disruption in barrier integrity. AD-derived BMEC cell lines also show an increased susceptibility to ethanol-induced barrier dysregulation at lower concentrations of ethanol (5 mM). Interestingly, our preliminary data shows that ethanol exposure seems to reduce BCRP efflux transporter activity in APP and PSEN1 AD cell lines.
 Conclusion and Scientific Impact and Implications:
 This study is novel in elucidating the enhanced disruption of BBB properties in familial AD-derived BMEC cell lines following ethanol exposure and provides insight into the potential harm of alcohol consumption in the development and/or exacerbation of BBB dysfunction in Alzheimer’s disease. Further studies will also unveil the possibility of ethanol-induced reduction of BCRP efflux transporter activity in APP and PSEN1 AD.

Cyclometalated ruthenium complexes overcome cisplatin resistance through PI3K/mTOR/Nrf2 signaling pathway.

Currently, cisplatin resistance remains a primary clinical obstacle in the successful treatment of non-small cell lung cancer. Here, we designed, synthesized, and characterized two novel cyclometalated Ru(II) complexes, [Ru(bpy)2(1-Ph-7-OCH3-IQ)] (PF6) (bpy=2,2'-bipyridine, IQ=isoquinoline, RuIQ7)and [Ru(bpy)2(1-Ph-6,7-(OCH3)2-IQ)] (PF6) (RuIQ8). As experimental controls, we prepared complex [Ru(bpy)2(1-Ph-IQ)](PF6) (RuIQ6) lacking a methoxy group in the main ligand. Significantly, complexes RuIQ6-8 displayed higher in vitro cytotoxicity when compared to ligands, precursor cis-[Ru(bpy)2Cl2], and clinical cisplatin. Mechanistic investigations revealed that RuIQ6-8 could inhibit cell proliferation by downregulating the phosphorylation levels of Akt and mTOR proteins, consequently affecting the rapid growth of human lung adenocarcinoma cisplatin-resistant cells A549/DDP. Moreover, the results from qRT-PCR demonstrated that these complexes could directly suppress the transcription of the NF-E2-related factor 2 gene, leading to the inhibition of downstream multidrug resistance-associated protein 1 expression and effectively overcoming cisplatin resistance. Furthermore, the relationship between the chemical structures of these three complexes and their anticancer activity, ability to induce cell apoptosis, and their efficacy in overcoming cisplatin resistance has been thoroughly examined and discussed. Notably, the toxicity test conducted on zebrafish embryos indicated that the three Ru-IQ complexes displayed favorable safety profiles. Consequently, the potential of these developed compounds as innovative therapeutic agents for the efficient and low-toxic treatment of NSCLC appears highly promising.

Cancer Drug Resistance Reduction via Co-treatment with Oxaliplatin and Nitazoxanide: Targeting the ABC Transporters.

Shortly after cancer is diagnosed, a phenomenon develops in cancer cells called multidrug resistance (MDR), in which cell sensitivity against anti-cancer drugs is significantly reduced. The present investigation aimed to assess the effects of nitazoxanide (NTZ), a safe drug, on LS174T/OXP-resistant cells. In the current in vitro research, the effects of NTZ and oxaliplatin (OXP) on the viability of LS174T and LS174T/OXP cell lines were evaluated through MTT assay. Then, the changes in expression levels of MDR1, MRP1, BCRP, and LRP genes and proteins were measured by RT-qPCR and western blotting methods, respectively. Lastly, the apoptosis status was assessed by annexin V-FITC/PI staining flow cytometry assay. The IC50 values for cells resistant or sensitive to OXP were revealed (11567 nM vs. 1745 nM; p <0.05 for 24 h incubation, and 5161 nM vs. 882.2 nM; p <0.05 for 48 h incubation). Moreover, NTZ plus OXP led to a leftward shift in the cytotoxicity curve (2004 nM; p = 0.007). This co-treatment significantly decreased the expression of all genes and proteins (p <0.05). Finally, the combination of NTZ and OXP induced a significant increase in apoptosis (p <0.001). The data showed that NTZ treatment could increase the sensitivity of LS174T/OXP cell line to the OXP cytotoxic effects. Thus, NTZ may be efficient in reducing drug resistance in clinics by means of the negative regulation of ATP-binding cassette (ABC) transporters. However, further studies are necessary to explain the exact mechanisms of NTZ.

Potential suppression of multidrug-resistance-associated protein 1 by coumarin derivatives: an insight from molecular docking and MD simulation studies

Human MRP1 protein plays a vital role in cancer multidrug resistance. Coumarins show promising pharmacological properties. Virtual screening, ADMET, molecular docking and molecular dynamics (MD) simulations were utilized as pharmacoinformatic tools to identify potential MRP1 inhibitors among coumarin derivatives. Using in silico ADMET, 50 hits were further investigated for their selectivity toward the nucleotide-binding domains (NBDs) of MRP1 using molecular docking. Accordingly, coumarin, its symmetrical ketone derivative Lig. No. 4, and Reversan were candidates for focused docking study with the NBDs domains compared with ATP. The result indicates that Lig. No. 4, with the best binding score, interacts with NBDs via hydrogen bonds with residues: GLN713, LYS684, GLY683, CYS682 in NBD1, and GLY1432, GLY771, SER769 and GLN1374 in NBD2, which mostly overlap with ATP binding residues. Moreover, doxorubicin (Doxo) was docked to the transmembrane domains (TMDs) active site of MRP1. Doxo interaction with TMDs was subjected to MD simulation in the NBDs free and occupied with Lig. No. 4 states. The results showed that Doxo interacts more strongly with TMD residues in inward facing feature of TMDs helices. However, when Lig. No. 4 exists in NBDs, Doxo interactions are different, and TMD helices show more outward-facing conformation. This result may suggest a partial competitive inhibition mechanism for the Lig. No. 4 on MRP1 compared with ATP. So, it may inhibit active complex formation by interfering with ATP entrance to NBDs and locking MRP1 conformation in outward-facing mode. This study suggests a valuable coumarin derivative that can be further investigated for potent MRP1 inhibitors. Communicated by Ramaswamy H. Sarma

A case report of unexplained persistent conjugated hyperbilirubinemia with normal liver transaminases over 23 years: remember Dubin-Johnson syndrome!

ObjectivesIn clinical practice, clinicians usually ignore the possibility of a rare genetic disease, i.e., Dubin-Johnson Syndrome (DJS), for conjugated hyperbilirubinemia caused by a mutation in the ABCC2 gene or in the MRP2 protein. Therefore, the objective is to alert the readers about our third reported case of DJS in Pakistan. Moreover, we also want to draw the attention of health professionals to potential pharmacotherapeutic management of DJS, and the management of the potential increased susceptibility to drug toxicity.Case reportWe present a case of 23 years old Asian man, with unexplained persistent conjugated hyperbilirubinemia and normal liver transaminases. In 1999, the patient was admitted to a tertiary care hospital for raised conjugated bilirubin (CB), i.e., 67% of total bilirubin (CB; 11 mg/dl, total bilirubin; 16.4 mg/dl). After 19 years, in 2018, during regular checkup by a family physician, the CB was 73% of total bilirubin (CB; 3 mg/dl, total bilirubin; 4.1 mg/dl), while the results of other clinical tests were unremarkable. Soon after 3 years, in 2021, the patient visited a gastroenterologist for jaundiced eyes. Comprehensive clinical tests (CB was 53% of total bilirubin) were accomplished to exclude the other causes of conjugated hyperbilirubinemia, and DJS was diagnosed.ConclusionsIn summary, it is strongly recommended that the cases of unexplained persistent conjugated hyperbilirubinemia should be evaluated for the presence of DJS. Similarly, the drugs that increase the clearance of CB could prove to be a potential management strategy for cases that negatively affect patient’s quality of life.

Abstracts from The Aerosol Society Drug Delivery to the Lungs 33.

Abstracts from The Aerosol Society Drug Delivery to the Lungs 33.

Genetic Polymorphisms in SLCO2B1 and ABCC1 Conjointly Modulate Atorvastatin Intracellular Accumulation in HEK293 Recombinant Cell Lines.

Although atorvastatin (ATV) is well-tolerated, patients may report muscle complaints. These are difficult to predict owing to high interindividual variability. Such side effects are linked to intramuscular accumulation of ATV. This study aimed to investigate the relative role of transporters expressed in muscle tissue in promoting or limiting drug access to cells. The impact of common single nucleotide polymorphisms (SNPs) in SLCO2B1 coding for OATP2B1 and ABCC1 coding for MRP1 on ATV transport was also evaluated. HEK293 cells were stably transfected with plasmids containing cDNA encoding wild-type or variant SLCO2B1 and/or ABCC1 to generate single and double stable transfectant HEK293 recombinant models overexpressing variant or wild-type OATP2B1 (influx) and/or MRP1 (efflux) proteins. Variant plasmids were generated by site-directed mutagenesis. Expression analyses were performed to validate recombinant models. Accumulation and efflux experiments were performed at different concentrations. ATV was quantified by LC-MS/MS, and kinetic parameters were compared between single and double HEK transfectants expressing wild-type and variant proteins. The results confirm the involvement of OATP2B1 and MRP1 in ATV cellular transport because it was demonstrated that intracellular accumulation of ATV was boosted by OATP2B1 overexpression, whereas ATV accumulation was decreased by MRP1 overexpression. In double transfectants, it was observed that increased ATV intracellular accumulation driven by OATP2B1 influx was partially counteracted by MRP1 efflux. The c.935G > A SNP in SLCO2B1 was associated with decreased ATV OATP2B1-mediated influx, whereas the c.2012G > T SNP in ABCC1 seemed to increase MRP1 efflux activity against ATV. Intracellular ATV accumulation is regulated by OATP2B1 and MRP1 transporters, whose functionality is modulated by natural genetic variants. This is significant because it may play a role in ATV muscle side-effect susceptibility.

Effect and Mechanism of Atorvastatin on Reversing Drug Resistance in Leukemia by Regulating Glycolysis through PTEN/mTOR Pathway

To investigate the influence and mechanism of atorvastatin on glycolysis of adriamycin resistant acute promyelocytic leukemia (APL) cell line HL-60/ADM. HL-60/ADM cells in logarithmic growth phase were treated with different concentrations of atorvastatin, then the cell proliferation activity was measured by CCK-8 assay, the apoptosis was detected by flow cytometry, the glycolytic activity was checked by glucose consumption test, and the protein expressions of PTEN, p-mTOR, PKM2, HK2, P-gp and MRP1 were detected by Western blot. After transfection of PTEN-siRNA into HL-60/ADM cells, the effects of low expression of PTEN on atorvastatin regulating the behaviors of apoptosis and glycolytic metabolism in HL-60/ADM cells were further detected. CCK-8 results showed that atorvastatin could inhibit the proliferation of HL-60/ADM cells in a concentration-dependent and time-dependent manner (r=0.872, r=0.936), and the proliferation activity was inhibited most significantly when treated with 10 μmol/L atorvastatin for 24 h, which was decreased to (32.3±2.18)%. Flow cytometry results showed that atorvastatin induced the apoptosis of HL-60/ADM cells in a concentration-dependent manner (r=0.796), and the apoptosis was induced most notably when treated with 10 μmol/L atorvastatin for 24 h, which reached to (48.78±2.95)%. The results of glucose consumption test showed that atorvastatin significantly inhibited the glycolytic activity of HL-60/ADM cells in a concentration-dependent and time-dependent manner (r=0.915, r=0.748), and this inhibition was most strikingly when treated with 10 μmol/L atorvastatin for 24 h, reducing the relative glucose consumption to (46.53±1.71)%. Western blot indicated that the expressions of p-mTOR, PKM2, HK2, P-gp and MRP1 protein were decreased in a concentration-dependent manner (r=0.737, r=0.695, r=0.829, r=0.781, r=0.632), while the expression of PTEN protein was increased in a concentration-dependent manner (r=0.531), when treated with different concentrations of atorvastatin for 24 h. After PTEN-siRNA transfected into HL-60/ADM cells, it showed that low expression of PTEN had weakened the promoting effect of atorvastatin on apoptosis and inhibitory effect on glycolysis and multidrug resistance. Atorvastatin can inhibit the proliferation, glycolysis, and induce apoptosis of HL-60/ADM cells. It may be related to the mechanism of increasing the expression of PTEN, inhibiting mTOR activation, and decreasing the expressions of PKM2 and HK2, thus reverse drug resistance.

Expression of the Group A Streptococcus Fibrinogen-Binding Protein Mrp Is Negatively Regulated by the Small Regulatory RNA FasX.

The group A Streptococcus (GAS; Streptococcus pyogenes) causes an elaborate array of human diseases. In part, such variability in disease potential is a consequence of GAS manipulating the expression of a catalogue of virulence factors, with regulation occurring at both the transcriptional and posttranscriptional levels. The GAS small regulatory RNA (sRNA) FasX contributes to this regulatory activity, enhancing expression of the thrombolytic agent streptokinase, and reducing expression of collagen (pili) and fibronectin (PrtF1 and PrtF2) -binding adhesins. Here, we expand insight into the regulatory targets of FasX by identifying the M-related protein (Mrp), a fibrinogen-binding adhesin with anti-phagocytic activity, as a negatively-regulated target of FasX. Importantly, investigation of the consequences of FasX-mediated regulation led to the discovery that FasX is a major positive regulator of GAS survival and proliferation in non-immune whole human blood, with a 30-fold difference in GAS cell numbers between a fasX mutant strain and isogenic parental and complemented mutant strains. No difference in cell numbers were observed when these strains were grown in human serum, consistent with the protective phenotype associated with FasX occurring due to the inhibition of cell (e.g., neutrophil) - mediated GAS killing. The FasX-regulated factor/s responsible for the blood survival phenotype remain to be defined. In summary, we expand the known FasX regulon and identify a new phenotype associated with the regulatory activity of this key GAS sRNA. IMPORTANCE Small regulatory RNAs (sRNAs) represent a major class of regulatory molecule that promotes the ability of the group A Streptococcus (GAS) and other pathogens to regulate virulence factor expression. Despite FasX being the best-described sRNA in GAS, there remains much to be learned. Here, we highlight the importance of FasX, identifying for the first time that the loss of this sRNA results in a major reduction in the ability of GAS to survive in human blood, a phenotype critical to the ability of this human-specific pathogen to cause severe invasive infections. We also identified a novel regulatory target of FasX, thereby expanding the known regulon of this key sRNA.

Bile Duct Ligation Impairs Function and Expression of Mrp1 at Rat Blood-Retinal Barrier via Bilirubin-Induced P38 MAPK Pathway Activations.

Liver injury is often associated with hepatic retinopathy, resulting from accumulation of retinal toxins due to blood–retinal barrier (BRB) dysfunction. Retinal pigment epithelium highly expresses MRP1/Mrp1. We aimed to investigate whether liver injury affects the function and expression of retinal Mrp1 using bile duct ligation (BDL) rats. Retinal distributions of fluorescein and 2,4-dinitrophenyl-S-glutathione were used for assessing Mrp1 function. BDL significantly increased distributions of the two substrates and bilirubin, downregulated Mrp1 protein, and upregulated phosphorylation of p38 and MK2 in the retina. BDL neither affected the retinal distribution of FITC-dextran nor expressions of ZO-1 and claudin-5, demonstrating intact BRB integrity. In ARPE-19 cells, BDL rat serum or bilirubin decreased MRP1 expression and enhanced p38 and MK2 phosphorylation. Both inhibiting and silencing p38 significantly reversed the bilirubin- and anisomycin-induced decreases in MRP1 protein. Apparent permeability coefficients of fluorescein in the A-to-B direction (Papp, A-to-B) across the ARPE-19 monolayer were greater than Papp, B-to-A. MK571 or bilirubin significantly decreased Papp, A-to-B of fluorescein. Bilirubin treatment significantly downregulated Mrp1 function and expression without affecting integrity of BRB and increased bilirubin levels and phosphorylation of p38 and MK2 in rat retina. In conclusion, BDL downregulates the expression and function of retina Mrp1 by activating the p38 MAPK pathway due to increased bilirubin levels.

Abstract 5452: Discovery of a novel seleno-leonurine analog as a potential therapeutic for ovarian cancer

Abstract Leonurine is an active alkaloid that is extracted from Traditional Chinese Medicine Herba leonuri. It has been reported to be beneficial for cardiovascular diseases, including atherosclerosis, acute and chronic myocardial infarction (MI), and ischemic stroke. Mao et al. illustrated that leonurine could up-regulate the expression of phosphorylated p38 and down-regulate phosphorylated Akt expression through inhibiting mitochondrial pathway, thus suppressing the proliferation and promoting lung cancer cell apoptosis. Accumulating evidence suggest that the extract of Leonurus sibiricus transgenic roots could induce apoptosis in different grades of human glioma cells and significantly promotes cisplatin sensitivity in cervical cancer cells via repressing cell proliferation, improving intrinsic cell apoptosis and inhibiting the expression of P-Gp and MRP1 protein, which has potential therapeutic value in cervical cancer treatment. In the present study, we designed and synthesized several selenium analogs of leonurine and their cytotoxicity were assessed using four different ovarian cancer cell lines viz. OVCAR-3, OVCAR-10, ES2, and drug resistant HeyA8 cells. Compared to the control and leonurine group, compound 834 inhibited the ovarian cancer cell viability in dose- and time-dependent manner. The IC50 values of compound 834 was 4.6 µM, 3.8 µM, 6.2 µM, and 5.7 µM for OVCAR-3, HeyA8, OVCAR-10, and ES2 cells, respectively, while for leonurine the IC50 value was &amp;gt;500 µM for 48 h treatment. To further acquaint the effect of 48 h treatment on cell proliferation, we performed trypan blue cell viability assay, trypan blue dye exclusion assay, Annexin V/7-AAD, Caspase 3/7 apoptosis assays and Western blotting of apoptotic proteins involved in apoptosis. Compound 834 significantly induced apoptosis in OVCAR-3 and HeyA8 cells in dose dependent manner. Upregulation of several apoptotic proteins, as evident by Western blot, suggested that 834 causes induction of apoptotic pathways efficiently. Further, the cell cycle analysis showed a significant arrest of OVCAR-3 and HeyA8 cells in the S-phase, which was further confirmed by the analysis of cyclin A2, cyclin-E1, p21 and p27 proteins expression. Conclusively, our research revealed that leonurine analog 834 significantly induces apoptosis in ovarian cancer cells via repressing cell proliferation, improving intrinsic cell apoptosis and inhibiting the expression of several signaling proteins, which has potential therapeutic value in ovarian cancer treatment. Citation Format: Asif Raza, Jacek Krzeminski, Shantu Amin, Arun Sharma. Discovery of a novel seleno-leonurine analog as a potential therapeutic for ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5452.

Design and fabrication of an integrated 3D dynamic multicellular liver-on-a-chip and its application in hepatotoxicity screening.

Nowadays, major methods of in vitro hepatotoxicity research are still based on traditional static two- or three-dimensional cell culture, although these means could investigate some toxic chemicals induced hepatotoxicity, but most of these toxicities failed to reappear in human, at least not in similar or calculable dose level. These failures may cause by the monoculture of only hepatocytes, ignored the signal communication to other non-parenchymal cells in liver tissue, also other complex microenvironment such as endothelial barrier, shear stress and other factors which were really existed in vivo but absent here, final leading to a low reliability of experimental results. In this study, a three-dimensional dynamic multi-cellular liver-on-a-chip device (3D-DMLoC) was developed to reproduce the microenvironment of in vivo liver tissue, including the simulation of hepatic sinusoid, perisinusoidal space and continuous liquid perfusion, hepatocytes could gather to some 3D cell spheroids in this chip. The perfusion could bring a real-time exchange of chemicals, nutrients, metabolites, supply suitable oxygen and a weak shear stress. The pressure and oxygen distribution inner the chip were simulated and evaluated by COMSOL Multiphysics software. HepaRG were co-cultured with HUVEC for 7 days in this chip, expression of hepatic polarization protein ZO-1 and MRP2, liver function factors ALB, UREA and CYP450s were almost all higher than in traditional static culture. Several drugs and heavy metal ions induced hepatotoxicity were then investigated, LDH released from hepatocyte spheroids in mostly 3D-DMLoC groups were higher than same-dosed 2D group, indicated the spheroids were more sensibility to the toxins. The hepatoxicity might be induced by acute hepatocytes injury according to the ratios of secreted AST/ALT contents. In conclusion, a liver-on-a-chip device was successfully developed and verified for better reproducing the in vivo physiological microenvironment of liver. It could be applied for easily, efficiently, and accurately screening the potential hepatotoxic chemicals in future.

Multidrug Resistance-Associated Protein 2 Deficiency Aggravates Estrogen-Induced Impairment of Bile Acid Metabolomics in Rats.

Multidrug resistance-associated protein 2 (Mrp2) mediates biliary secretion of anionic endobiotics and xenobiotics. Genetic alteration of Mrp2 leads to conjugated hyperbilirubinemia and predisposes to the development of intrahepatic cholestasis of pregnancy (ICP), characterized by increased plasma bile acids (BAs) due to mechanisms that are incompletely understood. Therefore, this study aimed to characterize BA metabolomics during experimental Mrp2 deficiency and ICP. ICP was modeled by ethinylestradiol (EE) administration to Mrp2-deficient (TR) rats and their wild-type (WT) controls. Spectra of BAs were analyzed in plasma, bile, and stool using an advanced liquid chromatography–mass spectrometry (LC–MS) method. Changes in BA-related genes and proteins were analyzed in the liver and intestine. Vehicle-administered TR rats demonstrated higher plasma BA concentrations consistent with reduced BA biliary secretion and increased BA efflux from hepatocytes to blood via upregulated multidrug resistance-associated protein 3 (Mrp3) and multidrug resistance-associated protein 4 (Mrp4) transporters. TR rats also showed a decrease in intestinal BA reabsorption due to reduced ileal sodium/bile acid cotransporter (Asbt) expression. Analysis of regulatory mechanisms indicated that activation of the hepatic constitutive androstane receptor (CAR)-Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway by accumulating bilirubin may be responsible for changes in BA metabolomics in TR rats. Ethinylestradiol administration to TR rats further increased plasma BA concentrations as a result of reduced BA uptake and increased efflux via reduced Slco1a1 and upregulated Mrp4 transporters. These results demonstrate that Mrp2-deficient organism is more sensitive to estrogen-induced cholestasis. Inherited deficiency in Mrp2 is associated with activation of Mrp3 and Mrp4 proteins, which is further accentuated by increased estrogen. Bile acid monitoring is therefore highly desirable in pregnant women with conjugated hyperbilirubinemia for early detection of intrahepatic cholestasis.

Tanshinone IIA prevents acetaminophen-induced nephrotoxicity through the activation of the Nrf2-Mrp2/4 pathway in mice.

It's known that APAP overdose often leads to hepatotoxicity and nephrotoxicity. In the present study, we investigated the preventative effect of Tan IIA on APAP-induced nephrotoxicity. Mice were orally administrated with Tan IIA (10 or 30 mg/kg/day) for 1 week and subsequently gavaged with 200 mg/kg of APAP. Tan IIA reduced APAP-induced nephrotoxicity as evidenced by histopathological evaluation and serum creatinine levels. Tan IIA pretreatment promoted the efflux of the toxic intermediate metabolite N-acetyl-p-benzoquinone imine (NAPQI), thus reduced its injury to mouse kidney. After Tan IIA pretreatment, a remarkable increase in mRNA and protein expression of Nrf2 and its target genes Mrp2 and Mrp4 was observed in Nrf2+/+ mice kidneys, however, no obvious change of Mrp2 and Mrp4 mRNA and protein expression was detected in Nrf2-/- mice kidneys. HK-2 cells were used for exploring the roles of Tan IIA in the Nrf2-MRPs pathway in vitro. Consistently, Tan IIA up-regulated the Nrf2-MRPs pathway and promoted the nuclear Nrf2 accumulation in HK-2 cells. Collectively, our findings suggested that Tan IIA facilitated the clearance of toxic intermediate metabolite NAPQI from the kidney through upregulation of the Nrf2-MRP2/4 pathway, thereby, performing preventive effects against APAP-induced nephrotoxicity.

Acquisition of paclitaxel resistance modulates the biological traits of gastric cancer AGS cells and facilitates epithelial to mesenchymal transition and angiogenesis.

This study aims to develop a paclitaxel (PTX)-resistant gastric cancer AGS cells (AGS-R) and evaluate the mechanisms of drug resistance. AGS cells were successively treated with increasing PTX concentrations. Cross-resistance of established AGS-R, the molecular patterns of cell survival, evasion of apoptosis, epithelial-mesenchymal transition (EMT), and the angiogenic potential were evaluated. AGS-R was induced within six months of PTX exposure. Extension of the treatment resulted in PTX-resistance beyond clinical levels. The established AGS-R showed resistance to vincristine and doxorubicin but not cisplatin. Upon induction of resistance, the expressions of MDR-1 (P < 0.001) and MRP-1 (P < 0.01) genes and proteins significantly increased. AGS-R cells had elevated levels of BCL-2, pro-CASP3, cleaved-NOTCH1, HES1, HEY1, NF-κB, PI3K, p-AKT, HIF-1α, Cyclin A, and B1 as compared with parental cells (at least P < 0.01). The protein levels of BAX, CASP3, P53, and P21 (at least P < 0.01) as well as intracellular ROS (P < 0.001) were reduced in AGS-R. A relative arrest at the G2/M phase (15.8 ± 0.75 vs. 26.7 ± 1.67) of the cell cycle and enrichment of AGS-R cells for CD44 marker (9 ± 0.6 vs. 1 ± 0.8) (P < 0.001) were detected by flow cytometry. While the E-cadherin expression was reduced (P < 0.001), the protein levels of Vimentin, N-cadherin, SLUG, and SNAIL were increased (at least P < 0.05). The angiogenic activity and release of VEGF and MMP2/9 were increased in AGS-R cells relative to the AGS line (P < 0.001). AGS-R cells could bypass chemotherapy stress by expressing the genes coding for efflux pumps and altering some key signaling in favor of survival, EMT, and angiogenesis.

Structures of multidrug resistance protein MRP4 reveal basis of substrate specificity

ATP-binding cassette (ABC) transporters are a ubiquitous family of transmembrane proteins which hydrolyze ATP to facilitate the movement of substrates across cell membranes. Despite common architectural features, individual eukaryotic ABC transporters have evolved to transport a broad spectrum of substrates. The multidrug resistance protein MRP4, a member of the MRP sub-family of transporters, has been linked to the efflux of diverse endogenous and exogenous substrates, including prostaglandins, cyclic nucleotides, conjugated steroids, and other chemical scaffolds.

Role of ubiquitin-specific peptidase 22 in multidrug resistance of colorectal cancer and its correlation with multidrug resistance gene P-gp

Objective: To investigate the role of ubiquitin-specific peptidase 22 (USP22) in colorectal cancer multidrug resistance and its correlation with multidrug resistance genes P-gp and MRP1, and to preliminarily explore the mechanism of USP22 affecting colorectal cancer resistance. Methods: USP22 over-expression plasmid was transfected into colorectal cancer cells (RKO, SW480)with low expression of USP22. Cell counting kit (CCK-8) assay was used to detect the effect of USP22 on oxaliplatin resistance in colorectal cancer cells. The cells were treated with oxaliplatin of the same concentration. Western blot method was used to detect the expression of apoptosis-related proteins cleaved-caspase3, Bcl-2, and drug resistance proteins MRP1, P-gp in the cells. The cell efflux test was used to detect the effect of up-regulated USP22 on Calcein-AM and rhodamine123. Immunohistochemical methods were used to detect the expressions of USP22 and P-gp in the oxaliplatin chemotherapy-sensitive group and the drug-resistant group and to analyze the correlation between USP22 and MRP1, P-gp. Results: CCK-8 assay showed that the IC50 values of SW480-USP22 (SW480 cells overexpressing USP22) treated with oxaliplatin for 24 h and 48 h was (4.62±0.05)μmol/L and (2.32±0.04)μmol/L respectively; which was 2.7 times and 3.0 times higher than that in control cells, respectively. After treating with 1.25 μmol/L oxaliplatin for 48 h, USP22 overexpression can inhibit SW480 cells apoptosis. The fluorescence intensity of calcein-AM and rhodamine123 in the SW480-USP22 group were significantly increased when compared with that in the control cells (both P<0.01). The protein expression levels of MRP1 and P-gp in SW480-USP22 cells were significantly increased when compared with that in the control cells(both P<0.01). Immunohistochemistry showed that the positive expression rates of USP22, MRP1, and P-gp in the oxaliplatin chemotherapy-sensitive group were significantly lower than those in the chemotherapy-resistant group, the difference was statistically significant (all P<0.05), and USP22 was positively correlated with the expressions of MRP1 and P-gp in colorectal cancer tissues (r1=0.377, r2=0.423, both P<0.05). Conclusions: The up-regulation of USP22 is related to the acquired resistance of colorectal cancer cells to oxaliplatin. USP22 may be involved in the process of platinum-based chemotherapy resistance of colorectal cancer by regulating the expressions of P-gp and MRP1.

Elevated N-Glycosylation Contributes to the Cisplatin Resistance of Non-Small Cell Lung Cancer Cells Revealed by Membrane Proteomic and Glycoproteomic Analysis.

Chemoresistance is the major restriction on the clinical use of cisplatin. Aberrant changes in protein glycosylation are closely associated with drug resistance. Comprehensive study on the role of protein glycosylation in the development of cisplatin resistance would contribute to precise elucidation of the complicated mechanism of resistance. However, comprehensive characterization of glycosylated proteins remains a big challenge. In this work, we integrated proteomic and N-glycoproteomic workflow to comprehensively characterize the cisplatin resistance-related membrane proteins. Using this method, we found that proteins implicated in cell adhesion, migration, response to drug, and signal transduction were significantly altered in both protein abundance and glycosylation level during the development of cisplatin resistance in the non-small cell lung cancer cell line. Accordingly, the ability of cell migration and invasion was markedly increased in cisplatin-resistant cells, hence intensifying their malignancy. In contrast, the intracellular cisplatin accumulation was significantly reduced in the resistant cells concomitant with the down-regulation of drug uptake channel protein, LRRC8A, and over-expression of drug efflux pump proteins, MRP1 and MRP4. Moreover, the global glycosylation was elevated in the cisplatin-resistant cells. Consequently, inhibition of N-glycosylation reduced cell resistance to cisplatin, whereas promoting the high-mannose or sialylated type of glycosylation enhanced the resistance, suggesting that critical glycosylation type contributes to cisplatin resistance. These results demonstrate the high efficiency of the integrated proteomic and N-glycoproteomic workflow in discovering drug resistance-related targets, and provide new insights into the mechanism of cisplatin resistance.