Inhibition Of Multidrug Resistance Research Articles

Overcoming multidrug resistance by reversan and exterminating glioblastoma and glioblastoma stem cells by delivering drug-loaded nanostructure hybrid lipid capsules (nHLCs).

Glioblastoma multiforme (GBM) is regarded as a highly aggressive brain cancer with a poor prognosis. There is an increase in the expression of P-glycoprotein (P-gp), responsible for multidrug resistance (MDR), making it a potential target for improving drug responses. Additionally, glioblastoma stem cells (GSCs) increase resistance to chemo- and radiotherapy and play a major role in cancer relapse. In this study, we targeted P-gp using a small molecule inhibitor, reversan (RV), to inhibit MDR that prolonged the retention of drugs in the cytosolic milieu. To eliminate GBM and GSCs, we have used two well-established anti-cancer drugs, regorafenib (RF) and curcumin (CMN). To improve the pharmacokinetics and decrease systemic delivery of drugs, we developed nanostructure hybrid lipid capsules (nHLCs), where hydrophobic drugs can be loaded in the core, and their physicochemical properties were determined by dynamic light scattering (DLS) and cryo-scanning electron microscopy (SEM). Inhibition of MDR by RV has also shown enhanced retention of nHLC in GBM cells. Co-delivery of drug-loaded nHLCs, pre-treated with RV, exhibited superior cytotoxicity in both GBM and GSCs than their individualdoses and effectively reduced the size and stemness of tumor spheres and accelerated the rate of apoptosis, suggesting a promising treatment for glioblastoma.

Probiotics: Lactic Acid Bacteria have Antibacterial Activity and Downregulate Biofilm Genes of Uropathogenic E. coli

Urinary tract infections (UTIs) are regarded as one of the most serious infections worldwide. Uro Pathogenic E. coli (UPEC) accounts for nearly 80% of UTI infections in females. This study investigated the antibacterial and antibiofilm effects of Lactobacillus acidophilus (l. acidophilus) and Lactobacillus plantarum (lb. plantarum) on multidrug-resistant E. coli obtained from urine samples. Complete bacteriological identification was conducted on 45 E. coli isolated from 80 urine samples of females with UTIs. Antibiotic susceptibility test was performed on all isolates by nine antibiotics. Ten out of the 45 isolates exhibited multidrug resistance (MDR). L. acidophilus and Lb. plantarum showed marked inhibition of MDR E. coli isolates on agar by a diffusion method (16 ± 0.04: 23 ± 0.05 mm). Moreover, L. acidophilus and Lb. plantarum strains inhibited the ability of UPEC to form a biofilm by 56.3% and 39.63%, respectively. The expression of biofilm genes of E. coli are as follows: csgA, crl, csgD showed remarkable downregulation after treatment with probiotics suspension: 0.00364: 0.19078 fold, 0.0005: 0.1894 fold, and 0.0490: 0.0883 for L. acidophilus, respectively. On the other hand, downregulation of biofilm gene expression for csgA, crl, csgD after treatment with Lb. plantarum suspension were expressed by fold changes as follows: 0.0769: 0.3535 fold, 0.05440: 0.12940 fold, and 0.06745: 0.4146, respectively. These findings show that L. acidophilus and Lb. plantarum exhibit potent antibacterial and antibiofilm action against MDR UPEC at both genotypic and phenotypic levels, and appear to be a promising solution in therapeutic applications for recurrent and persistent UTIs.

Inhibition of p38 MAPK increases the sensitivity of 5-fluorouracil-resistant SW480 human colon cancer cells to noscapine.

A major cause of treatment failure in advanced colon cancer is resistance to chemotherapy. p38 mitogen-activated protein kinase (MAPK) has been associated with cellular apoptosis and plays an important role in multidrug resistance (MDR) in cancer cells. In the present study the effect of p38 MAPK on the sensitivity of 5-fluorouracil (5-FU)-resistant SW480 (SW480/5-FU) human colon cancer cells to noscapine was investigated. Following p38 MAPK interference, the inhibitory effect of noscapine on cell viability and proliferation was increased in the SW480/5-FU cells and there was also a decrease in the expression level of minichromosome maintenance proteins, recombinant Ki-67 and proliferating cell nuclear antigen. Inhibition of p38 MAPK also enhanced noscapine-induced G1-phase cell cycle arrest in the SW480/5-FU cells and there was also a decrease in the protein and mRNA expression level of cyclin D, cyclin E and cyclin-dependent kinase 2, and an increase in the expression level of P57. Furthermore, p38 MAPK interference increased noscapine-induced apoptosis of the SW480/5-FU cells and there was an increase in the protein and mRNA expression level of caspases-3 and 8 and Bax, and decreased Bcl-2 expression level. The sensitivity of the SW480/5-FU cells to noscapine was also increased following p38 MAPK interference, as demonstrated by MDR inhibition via decreased Akt activity and reduced protein expression level of the MDR proteins P-glycoprotein, multidrug resistance protein 1 and ATP-binding cassette G2. These observations indicated that inhibition of p38 MAPK increased the sensitivity of the SW480/5-FU cells to noscapine by suppressing proliferation, induction of cell cycle arrest and apoptosis, and reversal of MDR in the SW480/5-FU cells.

Antimicrobial Activity of Combination Bacteriocin and Asam Sunti Extract (Averrhoa bilimbi L. fermented) Against Multidrug Resistant Escherichia coli in Lettuces (Lactuca sativa)

The ready-to-eat vegetables are often associated with the presence of multidrug-resistant (MDR) bacteria. This study aimed to evaluate the potency of bacteriocin, Asam Sunti extract, and their combination against MDR E. coli in lettuce. Their antimicrobial activity was assessed using the disk diffusion method and bacterial enumeration after direct application in pre-inoculated lettuce with MDR E. coli. The bacteriocin was produced by Lactobacillus plantarum BP102 at optimum production time or during the stationary phase at 18 h. These bacteriocins were able to inhibit five MDR E. coli isolates, while Asam Sunti extract and the combination of bacteriocin and Asam Sunti extract were only able to inhibit three MDR E. coli (LL1.2, LL3.11, and LL3.12) and (LL1.2, LL1.3, and LL3.11), respectively. In direct application to pre-inoculated fresh lettuce, higher inhibition of MDR E. coli was observed after applying the combination of bacteriocin and Asam Sunti extract with a ratio of 1:1 and 1:2, compared to bacteriocin alone. However, the inhibitory activity of this combination treatment was not significantly different (p>0.05) with the Asam Sunti extract alone. The highest rate of decrease in total bacteria in lettuces was 97% occurred in isolate LL1.2 with bacteriocin treatment alone, and isolate LL3.11 with combination treatment of bacteriocin and Asam Sunti extract (1:2). While on MCA media, the best reduction rate of 94% occurred in isolate LL1.2 with treatment using bacteriocin only, Asam Sunti extract only, and their combination (1:2). The inhibition of MDR E. coli in fresh lettuces by bacteriocin, Asam Sunti extract, and their combination was strain-dependent which was indicated by various inhibition results in all treatments. Key words: Asam Sunti extract, Bacteriocin, multidrug resistant.

Abnormal saccharides affecting cancer multi-drug resistance (MDR) and the reversal strategies.

Clinically, chemotherapy is the mainstay in the treatment of multiple cancers. However, highly adaptable and activated survival signaling pathways of cancer cells readily emerge after long exposure to chemotherapeutics drugs, resulting in multi-drug resistance (MDR) and treatment failure. Recently, growing evidences indicate that the molecular action mechanisms of cancer MDR are closely associated with abnormalities in saccharides. In this review, saccharides affecting cancer MDR development are elaborated and analyzed in terms of aberrant aerobic glycolysis and its related enzymes, abnormal glycan structures and their associated enzymes, and glycoproteins. The reversal strategies including depletion of ATP, circumventing the original MDR pathway, activation by or inhibition of sugar-related enzymes, combination therapy with traditional cytotoxic agents, and direct modification on the sugar moiety, are ultimately proposed. It follows that abnormal saccharides have a significant effect on cancer MDR development, providing a new perspective for overcoming MDR and improving the outcome of chemotherapy.

Nucleolin-Targeting AS1411 Aptamer-Modified Micelle for the Co-Delivery of Doxorubicin and miR-519c to Improve the Therapeutic Efficacy in Hepatocellular Carcinoma Treatment.

BackgroundMultidrug resistance (MDR) has emerged to be a major hindrance in cancer therapy, which contributes to the reduced sensitivity of cancer cells toward chemotherapeutic drugs mainly owing to the over-expression of drug efflux transporters. The combination of gene therapy and chemotherapy has been considered as a potential approach to improve the anti-cancer efficacy by reversing the MDR effect.Materials and MethodsThe AS1411 aptamer-functionalized micelles were constructed through an emulsion/solvent evaporation strategy for the simultaneous co-delivery of doxorubicin and miR-519c. The therapeutic efficacy and related mechanism of micelles were explored based on the in vitro and in vivo active targeting ability and the suppression of MDR, using hepatocellular carcinoma cell line HepG2 as a model.ResultsThe micelle was demonstrated to possess favorable cellular uptake and tumor penetration ability by specifically recognizing the nucleolin in an AS1411 aptamer-dependent manner. Further, the intracellular accumulation of doxorubicin was significantly improved due to the suppression of ABCG2-mediated drug efflux by miR-519c, resulting in the efficient inhibition of tumor growth.ConclusionThe micelle-mediated co-delivery of doxorubicin and miR-519c provided a promising strategy to obtain ideal anti-cancer efficacy through the active targeting function and the reversion of MDR.

Chondroitin sulfate-based nanoparticles for enhanced chemo-photodynamic therapy overcoming multidrug resistance and lung metastasis of breast cancer

As a major therapeutic approach for cancer treatment, the effectiveness of chemotherapy is challenged by multidrug resistance (MDR). Herein, we fabricated novel redox-responsive, chondroitin sulfate-based nanoparticles that could simultaneously deliver quercetin (chemosensitizer), chlorin e6 (photosensitizer) and paclitaxel (chemotherapeutic agent) to exert enhanced chemo-photodynamic therapy for overcoming MDR and lung metastasis of breast cancer. In vitro cell study showed that nanoparticles down-regulated the expression of P-glycolprotein (P-gp) on MCF-7/ADR cells and thereby improved the anticancer efficacy of PTX against MCF-7/ADR cells. Moreover, NIR laser irradiation could induce nanoparticles to generate cellular reactive oxygen species (ROS), leading to mitochondrial membrane potential loss, and meanwhile facilitating lysosomal escape of drugs. Importantly, the novel nanoplatform exhibited effective in vivo MDR inhibition and anti-metastasis efficacy through enhanced chemo-photodynamic therapy. Thus, the study suggested that the multifunctional nanoplatform had good application prospect for effective breast cancer therapy.

Photodynamic Inactivation of Bacteria with Porphyrin Derivatives: Effect of Charge, Lipophilicity, ROS Generation, and Cellular Uptake on Their Biological Activity In Vitro.

Resistance of microorganisms to antibiotics has led to research on various therapeutic strategies with different mechanisms of action, including photodynamic inactivation (PDI). In this work, we evaluated a cationic, neutral, and anionic meso-tetraphenylporphyrin derivative’s ability to inactivate the Gram-negative and Gram-positive bacteria in a planktonic suspension under blue light irradiation. The spectroscopic, physicochemical, redox properties, as well as reactive oxygen species (ROS) generation capacity by a set of photosensitizers varying in lipophilicity were investigated. The theoretical calculations were performed to explain the distribution of the molecular charges in the evaluated compounds. Moreover, logP partition coefficients, cellular uptake, and phototoxicity of the photosensitizers towards bacteria were determined. The role of a specific microbial efflux pump inhibitor, verapamil hydrochloride, in PDI was also studied. The results showed that E. coli exhibited higher resistance to PDI than S. aureus (3–5 logs) with low light doses (1–10 J/cm2). In turn, the prolongation of irradiation (up to 100 J/cm2) remarkably improved the inactivation of pathogens (up to 7 logs) and revealed the importance of photosensitizer photostability. The PDI potentiation occurs after the addition of KI (more than 3 logs extra killing). Verapamil increased the uptake of photosensitizers (especially in E. coli) due to efflux pump inhibition. This effect suggests that PDI is mediated by ROS, the electrostatic charge interaction, and the efflux of photosensitizers (PSs) regulated by multidrug-resistance (MDR) systems. Thus, MDR inhibition combined with PDI gives opportunities to treat more resistant bacteria.

Role of Multidrug Resistance Proteins in Nonresponders to Immunomodulatory Therapy for Noninfectious Uveitis.

PurposeNearly a third to half of patients with noninfectious uveitis (NIU) fail to achieve control with immunomodulatory therapy (IMT). Multidrug resistance (MDR) proteins are transmembrane proteins that allow efflux of intracellular drugs, leading to drug resistance. The aim of our study was to compare MDR protein function in blood CD4+ cells between responders and nonresponders to IMT.MethodsWe included NIU patients on IMT for ≥6 months and corticosteroid dose ≤10 mg/d. Nonresponders to treatment were those with worsening (two or more steps) of inflammation in the past 3 months on full-dose immunosuppressive therapy. MDR function was assessed by Rhodamine-123 dye retention in blood CD4+ cells. Three nonresponders were treated with adjunctive oral cyclosporine A (CSA, MDR inhibitor) therapy for 2 months and reevaluated.ResultsFourteen NIU patients were recruited. Most (n = 8) had Vogt-Koyanagi-Harada disease. These included nine nonresponders and five responders to IMT. Nonresponders produced significantly higher MDR function and proinflammatory cytokines (interferon γ, tumor necrosis factor α, interleukin 17, and Granulocyte Macrophage Colony Stimulating Factor (GM-CSF)) than responders. In vitro CSA treatment of CD4+ cells inhibited MDR expression and proinflammatory cytokine production while increasing Foxp3. Finally, adjunctive oral CSA therapy led to improvement in clinical inflammatory scores with a concurrent decrease in MDR function and proinflammatory cytokine secretion.ConclusionsMDR function is significantly higher in CD4+ T cells of nonresponders to IMT. Adjunctive CSA therapy may decrease MDR function and allow improvement in treatment response to IMT.Translational RelevanceOur study highlights the need for MDR inhibition strategies in NIU patients not responding to IMT for improving the efficacy of anti-inflammatory therapy.

Antiquorum sensing and antibiofilm potential of biosynthesized silver nanoparticles of Myristica fragrans seed extract against MDR Salmonella enterica serovar Typhi isolates from asymptomatic typhoid carriers and typhoid patients

Globally, Salmonella infection poses a major public health problem. Here, we report antibiofilm activity and quorum sensing inhibition of aqueous seeds extract of Myristica fragrans (nutmeg) and biosynthesized silver nanoparticles (AgNPs) against multidrug resistant (MDR) Salmonella enterica serovar Typhi (S. Typhi) isolated from typhoid patients and asymptomatic carriers. S. Typhi isolates revealed higher percentage (46%) of biofilm production identified by tissue culture plate (TCP) than Congo red agar (CRA) and tube adherence (TA) methods. The inhibition of biofilm-producing MDR S. Typhi isolates and pigment production of Chromobacterium violaceum (indicator bacteria) demonstrated the quorum sensing potential of nutmeg. The aqueous seed extract of nutmeg exhibited 87% of antibiofilm activity, while the biosynthesized AgNPs showed 99.1% of antibiofilm activity. Molecular docking studies of bioactive compounds of nutmeg against transcriptional regulatory protein RcsB and sensor kinase protein RcsC revealed interaction with the target proteins. It is proposed that biosynthesized AgNPs could be used as one of the effective candidates in treating asymptomatic typhoid carriers or typhoid patients and to control the subsistence of biofilm-producing S. Typhi strains or other pathogenic bacteria in the environment or industrial settings.

Multifunctional Nanosystem for Targeted and Controlled Delivery of Multiple Chemotherapeutic Agents for the Treatment of Drug-Resistant Breast Cancer.

By targeting CD44 receptors, inhibiting multidrug resistance (MDR), controlling drug release, and synergistically inhibiting tumor growth, a multilayered nanosystem was developed to serve as a multifunctional platform for the treatment of drug-resistant breast cancers. The multilayer nanosystem is composed of a poly(lactic-co-glycolic acid) core, a liposome second layer, and a chitosan third layer. The chitosan-multilayered nanoparticles (Ch-MLNPs) can co-deliver three chemotherapeutic agents: doxorubicin (DOX), paclitaxel (PTX), and silybin. The three drugs are released from the multilayered NPs in a controlled and sequential manner upon internalization and localization in the cellular endosomes. The presence of a chitosan layer allows the nanosystem to target a well-characterized MDR breast cancer biomarker, the CD44s receptor. In vitro cytotoxicity study showed that the nanosystem loaded with triple drugs, DOX–PTX–silybin, resulted in better antitumor efficacy than the single-drug or dual-drug nano-formulations. Likely attributed to the MDR-inhibition effect of silybin, the co-delivered DOX and PTX exhibited a better synergistic effect on MDR breast cancer cells than on non-MDR breast cancer cells. The in vivo study also showed that the multilayered nanosystem promoted MDR inhibition and synergy between chemotherapeutic agents, leading to significant tumor reduction in a xenograft animal model. Ch-MLNPs reduced the tumor volume by fivefold compared to that of the control group without causing overt cytotoxicity.

Star-shaped polymer of β‑cyclodextrin-g-vitamin E TPGS for doxorubicin delivery and multidrug resistance inhibition.

Multidrug resistance (MDR) remains as an obstacle for effective cancer treatment. Herein, we developed a novel and efficient nanomedicine by virtue of the carrier characters and MDR inhibition effects of β-cyclodextrin (β-CD) and d-α-tocopheryl polyethylene glycol succinate (TPGS). A series of star-shaped polymers CD-g-TPGS with different TPGS substitution degree were synthesized for doxorubicin (DOX) delivery, where β-CD was identified as a core and TPGS as branches. These star polymers can self-assemble into nanoparticles with DOX. These nanoparticles showed no significant differences in size, zeta potential and morphology except for in vitro stability. They demonstrated good biocompatibility and enhanced cellular uptake in both drug sensitive and resistant cancer cells. Notably, the nanoparticles exhibited superiority of cytotoxicity in drug resistant cancer cells against free DOX. In vivo antitumor effect also demonstrated the improved cancer inhibition effect. This work suggests that star-shaped polymers CD-g-TPGS are promising drug carriers to overcome MDR in cancer treatment.

Involvement of α-methylene-γ- and δ-lactones in the suppression of multidrug resistance in MCF-7 cells.

The development of multidrug resistance to chemotherapy remains a challenge in the treatment of cancer and is a major factor causing failure of many forms of chemotherapy. The ATP binding cassette (ABC) family of proteins are efflux pumps that transport various potentially dangerous substances out of the cells. Several of the ABC transporters are related to chemoresistance, as the rapidly dividing malignant cells use them to protect themselves from medical interventions. Inhibitors of ABC transporters have the potential to enhance the efficacy of anticancer drugs. Two new synthetic compounds, AD-06 and AD-013, were tested as possible multidrug resistance inhibitors in MCF-7 cells. The cytotoxicity of new compounds was tested in MCF-7 and MCF-10A cell lines using the MTT method. Gene expression was measured by real-time PCR and changes in the protein levels were evaluated by flow cytometry and ELISA. A method based on the use of a fluorescent dye, being a marker of the ABC transporter activity, was used for screening the tested compounds as potential multidrug resistance inhibitors. AD-06 and AD-013 down-regulated NF-κB mRNA levels and decreased the population of cells with activated NF-κB. Both compounds were found to be strong ABCB1 and ABCG2 transporter inhibitors. They showed synergistic effects when incubated with taxol or oxaliplatin. α-Methylene-γ- and -δ-lactones AD-06 and AD-013 are promising lead structures for further development as multidrug resistance inhibitors.

Integration of phospholipid-hyaluronic acid-methotrexate nanocarrier assembly and amphiphilic drug-drug conjugate for synergistic targeted delivery and combinational tumor therapy.

Combinational cancer therapy has been considered as a promising strategy to achieve synergetic therapeutic effects and suppression of multidrug resistance. Herein, we adopted a combination of methotrexate (MTX), an antimetabolite acting on cytoplasm, and 10-hydroxycamptothecin (HCPT), an alkaloid acting on nuclei, to treat cancer. Given the different solubilities, membrane permeabilities, and anticancer mechanisms of both drugs, we developed a dual-targeting delivery system based on 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-hyaluronic acid (a principal ligand of CD44 receptors)-MTX (a selective ligand of folate receptors) nanoparticles, which was exploited to carry HCPT-MTX conjugate for synergistically boosting dual-drug co-delivery. The HCPT-MTX conjugate was synthesized by a blood-stable yet intracellularly hydrolysable ester bond. The core-shell-corona DSPE-HA-MTX nanoparticles encapsulating HCPT-MTX (HCPT-MTX@DHM) exhibited high drug entrapment efficiency (∼91.8%) and pH/esterase-controlled release behavior. Cellular uptake studies confirmed significant increase in the efficiency of selective internalization of HCPT-MTX@DHM via CD44/folate receptors compared with those of DSPE-HA nanoparticles encapsulating HCPT-MTX (HCPT-MTX@DH), both drugs, or each individual drug. Furthermore, in vivo near-infrared fluorescence and photoacoustic dual-modal imaging indicated that DiR-doped HCPT-MTX@DHM nanoparticles efficiently accumulated at the tumor sites through passive-plus-active targeting. Finally, the synergistic active targeting and synchronous dual-drug release at a synergistic drug-to-drug ratio resulted in highly synergetic tumor cell-killing and tumor growth inhibition in MCF-7 tumor-bearing mice. Therefore, HCPT-MTX@DHM nanoparticles can be an efficient and smart platform for tumor-targeting therapy.

Concurrently suppressing multidrug resistance and metastasis of breast cancer by co-delivery of paclitaxel and honokiol with pH-sensitive polymeric micelles.

Multidrug resistance (MDR) and metastasis are considered to be two of the major barriers for successful chemotherapy. The combination of a chemotherapeutic drug with a modulator has emerged as a promising strategy for efficiently treating MDR cancer and preventing tumor metastasis. Herein, a dual drug (paclitaxel and honokiol)-loaded pH-sensitive polymeric micelle system based on PEOz-PLA was successfully fabricated to ensure that tumor MDR and metastasis could be concurrently suppressed, therefore achieving distinguishing endo/lysosomal pH from physiological pH by accelerating drug release and then enhancing the cytotoxicity of paclitaxel to drug-resistant tumor cells MCF-7/ADR by increasing cellular uptake of paclitaxel, preventing in vitro invasion and migration for MDA-MB-231 cells and in vivo metastasis in nude mice. Further, the mechanism of MDR reversal by dual drug-loaded PEOz-PLA micelles was elucidated to be down-regulation of P-gp expression and increase of plasma membrane fluidity of MCF-7/ADR cells. The present findings strengthen the usefulness of co-delivery of PTX and HNK by pH-responsive polymeric micelles for suppression of tumor MDR and metastasis.

Lipid nanocarriers for tamoxifen citrate/coenzyme Q10 dual delivery

Nanotechnology based combinatorial therapy has emerged as an effective strategy for cancer treatment due to its synergistic activity, suppression of multi-drug resistance and successful delivery to target site. The objective of this work was to develop and characterize tamoxifen citrate (TC) and coenzyme Q10 (CoQ10) lipid nanocarriers for oral breast cancer chemotherapy. Stearic acid (2%w/v) and poloxamer188 (3%w/v) were selected as optimal lipid matrix and surfactant for development of solid lipid nanocarriers (SLNs). Incorporation of lecithin into lipid matrix (SLN9) significantly reduced particle size to 180 nm and increased %EE of CoQ10 (45%). Nanostructured lipid carriers containing 10% Labrafac oil showed further decrease in particle size reaching only 81 nm and increased %EE up to 94% and 56% for TC and CoQ10, respectively. Lipid nanocapsules showed more prominent effect on decreasing particle size (36 nm). Lipid nanocarriers offered controlled drug release profiles. The study showed that lipid carriers significantly improved drugs permeation through rabbit intestinal mucosa and suggested them as potential delivery systems for improving the bioavailability of TC/CoQ10 therapeutic molecules. Subsequent studies will be performed in order to elucidate the cytotoxicity and genotoxicity of selected lipid nanocarriers formulas on MCF-7 (adenocarcinoma breast cancer cells) versus normal cells (WISH cell line).

Cucurbitacin B reverses multidrug resistance by targeting CIP2A to reactivate protein phosphatase 2A in MCF-7/adriamycin cells.

Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a human oncoprotein that is overexpressed in various tumors. A previous study found that CIP2A expression is associated with doxorubicin (Dox) resistance. In the present study, we investigated whether cucurbitacin B (CuB), a natural anticancer compound found in Cucurbitaceae, reversed multidrug resistance (MDR) and downregulated CIP2A expression in MCF-7/Adriamycin (MCF-7/Adr) cells, a human breast multidrug-resistant cancer cell line. CuB treatment significantly suppressed MCF-7/Adr cell proliferation, and reversed Dox resistance. CuB treatment also induced caspase-dependent apoptosis, decreased phosphorylation of Akt (pAkt). The suppression of pAkt was mediated through CuB-induced activation of protein phosphatase 2A (PP2A). Furthermore, CuB activated PP2A through the suppression of CIP2A. Silencing CIP2A enhanced CuB-induced growth inhibition, apoptosis and MDR inhibition in MCF-7/Adr cells. In conclusion, we found that enhancement of PP2A activity by inhibition of CIP2A promotes the reversal of MDR induced by CuB.

Dielectrophoretic Microfluidic Chip Enables Single-Cell Measurements for Multidrug Resistance in Heterogeneous Acute Myeloid Leukemia Patient Samples.

The front-line treatment for adult acute myeloid leukemia (AML) is anthracycline-based combination chemotherapy. However, treatment outcomes remain suboptimal with relapses frequently observed. Among the mechanisms of treatment failure is multidrug resistance (MDR) mediated by the ABCB1, ABCC1, and ABCG2 drug-efflux transporters. Although genetic and phenotypic heterogeneity between leukemic blast cells is a well-recognized phenomenon, there remains minimal data on differences in MDR activity at the individual cell level. Specifically, functional assays that can distinguish the variability in MDR activity between individual leukemic blasts are lacking. Here, we outline a new dielectrophoretic (DEP) chip-based assay. This assay permits measurement of drug accumulation in single cells, termed same-single-cell analysis in the accumulation mode (SASCA-A). Initially, the assay was optimized in pretherapy samples from 20 adults with AML whose leukemic blasts had MDR activity against the anthracyline daunorubicin (DNR) tested using multiple MDR inhibitors. Parameters tested were initial drug accumulation, time to achieve signal saturation, fold-increase of DNR accumulation with MDR inhibition, ease of cell trapping, and ease of maintaining the trapped cells stationary. This enabled categorization into leukemic blast cells with MDR activity (MDR(+)) and leukemic blast cells without MDR activity (MDR(-ve)). Leukemic blasts could also be distinguished from benign white blood cells (notably these also lacked MDR activity). MDR(-ve) blasts were observed to be enriched in samples taken from patients who went on to enter complete remission (CR), whereas MDR(+) blasts were frequently observed in patients who failed to achieve CR following front-line chemotherapy. However, pronounced variability in functional MDR activity between leukemic blasts was observed, with MDR(+) cells not infrequently seen in some patients that went on to achieve CR. Next, we tested MDR activity in two paired AML patient samples. Pretherapy samples taken from patients that achieved CR to front-line chemotherapy were compared with samples taken at time of subsequent relapse. MDR(+) cells were frequently observed in leukemic blast cells in both pretherapy and relapsed samples, consistent with MDR as a mechanism of relapse in these patients. We demonstrate the ability of a new DEP microfluidic chip-based assay to identify heterogeneity in MDR activity in leukemic blasts. The test provides a platform for future studies to characterize the mechanistic basis for heterogeneity in MDR activity at the individual cell level.

Synthesis and bioevaluation of novel benzodipyranone derivatives as P-glycoprotein inhibitors for multidrug resistance reversal agents

Multidrug resistance (MDR) is a phenomenon in which cells become resistant to structurally and mechanistically unrelated drugs, and it is one of the emerging problems in cancer therapy today. The relation between overexpression of the ABC transporter subfamily B member 1 (ABCB1/P-glycoprotein) and resistant cancers has been well characterized. In the present study, we successfully synthesized 52 novel benzodipyranone analogs and evaluated for their P-gp inhibitory activity in a P-gp transfected cell line, ABCB1/Flp-In™-293. Among these derivatives, 5a bearing on the 3-methylphenyl substituent, displayed the most potent P-gp inhibitory activity, which can enable the increase of the intracellular accumulation of P-gp substrate Calcein-AM. 5a exhibited more potency on promoted anticancer drugs cytotoxicity by reversing P-gp-mediated drug resistance in both ABCB1/Flp-In™-293 and KBvin cell lines. In particular, the compound 5a sensitized ABCB1/Flp-In™-293 cells toward paclitaxel, vincristine, and doxorubicin by 16.1, 21.0, and 1.6-fold at 10 μM, respectively. Further, 5a dramatically sensitized the resistant cell line KBvin toward paclitaxel and vincristine by 23.1 and 29.7-fold at 10 μM, respectively. It's possible that its mechanism of MDR inhibition can restore the intracellular accumulation of drugs and eventually chemosensitize cancer cells to anticancer drugs and reduce ABCB1 mRNA expression level.

Suppression of multidrug resistance by rosiglitazone treatment in human ovarian cancer cells through downregulation of FZD1 and MDR1 genes.

Multidrug resistance (MDR) is a major obstacle in the successful treatment of ovarian cancer. One of the most common causes of MDR is overexpression of P-glycoprotein (P-gp), encoded by the MDR1 gene. The MDR1 gene is a direct target of the Wnt/β-catenin signaling pathway, which plays an important role in ovarian cancer. Peroxisome proliferator-activated receptor γ (PPARγ) ligands have been found to protect against development of cancer through the Wnt/β-catenin pathway. To investigate the effect of PPARγ ligands on MDR1/P-gp expression, we treated a MDR ovarian cancer cell subline, A2780/Taxol, with different concentrations of rosiglitazone (Rosi), a member of the synthetic PPARγ ligands. Rosi downregulated FZD1 and MDR1/P-gp expression in a concentration-dependent manner. In addition, nuclear β-catenin levels and its transcriptional activity decreased significantly. In conclusion, Rosi may reverse MDR of ovarian cancer cells by downregulating the Wnt/β-catenin pathway with the suppression of FZD1.