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Sample records for drugs mutually inhibit

  1. [Mutual inhibition between positive and negative emotions].

    PubMed

    Shimokawa, A

    1994-02-01

    The purpose of this study is to examine the relationship between positive and negative emotions. In study 1, 62 emotional items were selected in order to measure subjective emotional experiences. In study 2, comics, photos and poems were randomly presented to 1,220 college students to induce emotion. Subjects were asked to rate their momentary emotional intensity on two set of 5-point scales (general emotional intensity scale and 62 specific emotional intensity scale). In analysis 1, positive correlations were suggested between general emotional intensity scale and some of the specific emotional intensity scales which were activated by stimuli. In analysis 2, 10 positive and 10 negative emotional items were extracted from 62 items by factor analysis. In analysis 3, 4 and 5, it became clear that the distribution of frequency of correlations of 10 positive x 10 negative items changed according to the general emotional intensity scale. That is, from low to moderate levels of GEIS, the two kinds of emotion had no or slightly positive correlation, but at high level they became to be negatively correlated. From the facts described above, it is concluded that positive and negative emotions is not always independent, but show mutual inhibition in case of high intensity level of one of each emotions. PMID:8201808

  2. Drugs that inhibit complement.

    PubMed

    Schrezenmeier, Hubert; Höchsmann, Britta

    2012-02-01

    The complement system is an important part of the innate immune system. Complement plays a crucial role in the pathophysiology of many disorders. Despite the pivotal role of the complement system, an approved targeted inhibitor of a complement factor became available only recently. Eculizumab is a humanized monoclonal antibody that inhibits complement factor C5. It is a targeted, disease modifying, treatment of paroxysmal nocturnal hemoglobinuria (PNH). It was approved be the US FDA and the European Commission in 2007. In this review we will update the experience with eculizumab in PNH and discuss potential use of eculizumab in other disorders (e.g. cold agglutinin disease; atypical HUS) and new approaches to complement inhibition with drugs other than eculizumab. PMID:22169380

  3. Ungulate saliva inhibits a grass–endophyte mutualism

    PubMed Central

    Tanentzap, Andrew J.; Vicari, Mark; Bazely, Dawn R.

    2014-01-01

    Fungal endophytes modify plant–herbivore interactions by producing toxic alkaloids that deter herbivory. However, studies have neglected the direct effects herbivores may have on endophytes. Antifungal properties and signalling effectors in herbivore saliva suggest that evolutionary pressures may select for animals that mitigate the effects of endophyte-produced alkaloids. Here, we tested whether saliva of moose (Alces alces) and European reindeer (Rangifer tarandus) reduced hyphal elongation and production of ergot alkaloids by the foliar endophyte Epichloë festucae associated with the globally distributed red fescue Festuca rubra. Both moose and reindeer saliva reduced the growth of isolated endophyte hyphae when compared with a treatment of distilled water. Induction of the highly toxic alkaloid ergovaline was also inhibited in plants from the core of F. rubra's distribution when treated with moose saliva following simulated grazing. In genotypes from the southern limit of the species' distribution, ergovaline was constitutively expressed, as predicted where growth is environmentally limited. Our results now present the first evidence, to our knowledge, that ungulate saliva can combat plant defences produced by a grass–endophyte mutualism. PMID:25055816

  4. Ungulate saliva inhibits a grass-endophyte mutualism.

    PubMed

    Tanentzap, Andrew J; Vicari, Mark; Bazely, Dawn R

    2014-07-01

    Fungal endophytes modify plant-herbivore interactions by producing toxic alkaloids that deter herbivory. However, studies have neglected the direct effects herbivores may have on endophytes. Antifungal properties and signalling effectors in herbivore saliva suggest that evolutionary pressures may select for animals that mitigate the effects of endophyte-produced alkaloids. Here, we tested whether saliva of moose (Alces alces) and European reindeer (Rangifer tarandus) reduced hyphal elongation and production of ergot alkaloids by the foliar endophyte Epichloë festucae associated with the globally distributed red fescue Festuca rubra. Both moose and reindeer saliva reduced the growth of isolated endophyte hyphae when compared with a treatment of distilled water. Induction of the highly toxic alkaloid ergovaline was also inhibited in plants from the core of F. rubra's distribution when treated with moose saliva following simulated grazing. In genotypes from the southern limit of the species' distribution, ergovaline was constitutively expressed, as predicted where growth is environmentally limited. Our results now present the first evidence, to our knowledge, that ungulate saliva can combat plant defences produced by a grass-endophyte mutualism. PMID:25055816

  5. An obligatory bacterial mutualism in a multi-drug environment exhibits strong oscillatory population dynamics

    NASA Astrophysics Data System (ADS)

    Conwill, Arolyn; Yurtsev, Eugene; Gore, Jeff

    2014-03-01

    A common mechanism of antibiotic resistance in bacteria involves the production of an enzyme that inactivates the antibiotic. By inactivating the antibiotic, resistant cells can protect other cells in the population that would otherwise be sensitive to the drug. In a multidrug environment, an obligatory mutualism arises because populations of different strains rely on each other to breakdown antibiotics in the environment. Here, we experimentally track the population dynamics of two E. coli strains in the presence of two different antibiotics: ampicillin and chloramphenicol. Together the strains are able to grow in antibiotic concentrations that inhibit growth of either one of the strains alone. Although mutualisms are often thought to stabilize population dynamics, we observe strong oscillatory dynamics even when there is long-term coexistence between the two strains. We expect that our results will provide insight into the evolution of antibiotic resistance and, more generally, the evolutionary origin of phenotypic diversity, cooperation, and ecological stability.

  6. Drug interactions: inhibition of acetaminophen glucuronidation by drugs.

    PubMed

    Bolanowska, W; Gessner, T

    1978-07-01

    Glucuronidation of [3H]acetaminophen (APAP) was studied in rat liver preparations. Both Triton X-100 and UDP-N acetylglucosamine (UDPAG) activated 3- to 4-fold the glucuronidation of APAP by liver homogenates or microsomes. Prednisolone inhibited microsomal glucuronidation of APAP, yielding apparent noncompetitive kinetics in native and in UDPAG-activated microsomes. Studies with UDPAG-activated microsomal preparations show that many drugs can inhibit glucuronidation of APAP markedly; among the most poten inhibitors are: morphine, dicumarol, hydroxyzine, phenolphthalein, chloramphenicol and tetracycline. PMID:660554

  7. Flurbiprofen-antioxidant mutual prodrugs as safer nonsteroidal anti-inflammatory drugs: synthesis, pharmacological investigation, and computational molecular modeling.

    PubMed

    Ashraf, Zaman; Alamgeer; Kanwal, Munazza; Hassan, Mubashir; Abdullah, Sahar; Waheed, Mamuna; Ahsan, Haseeb; Kim, Song Ja

    2016-01-01

    Flurbiprofen-antioxidant mutual prodrugs were synthesized to reduce the gastrointestinal (GI) effects associated with flurbiprofen. For reducing the GI toxicity, the free carboxylic group (-COOH) was temporarily masked by esterification with phenolic -OH of natural antioxidants vanillin, thymol, umbelliferone, and sesamol. The in vitro hydrolysis of synthesized prodrugs showed that they were stable in buffer solution at pH 1.2, indicating their stability in the stomach. The synthesized prodrugs undergo significant hydrolysis in 80% human plasma and thus release free flurbiprofen. The minimum reversion was observed at pH 1.2, suggesting that prodrugs are less irritating to the stomach than flurbiprofen. The anti-inflammatory, analgesic, antipyretic, and ulcerogenic activities of prodrugs were evaluated. All the synthesized prodrugs significantly (P<0.001) reduced the inflammation against carrageenan and egg albumin-induced paw edema at 4 hours of study. The reduction in the size of the inflamed paw showed that most of the compounds inhibited the later phase of inflammation. The prodrug 2-oxo-2H-chromen-7-yl-2-(2-fluorobiphenyl-4-yl)propanoate (4b) showed significant reduction in paw licking with percentage inhibition of 58%. It also exhibited higher analgesic activity, reducing the number of writhes with a percentage of 75%, whereas flurbiprofen showed 69% inhibition. Antipyretic activity was investigated using brewer's yeast-induced pyrexia model, and significant (P<0.001) reduction in rectal temperature was shown by all prodrugs at all times of assessment. The results of ulcerogenic activity showed that all prodrugs produced less GI irritation than flurbiprofen. Molecular docking and simulation studies were carried out with cyclooxygenase (COX-1 and COX-2) proteins, and it was observed that our prodrugs have more potential to selectively bind to COX-2 than to COX-1. It is concluded that the synthesized prodrugs have promising pharmacological activities with

  8. Flurbiprofen–antioxidant mutual prodrugs as safer nonsteroidal anti-inflammatory drugs: synthesis, pharmacological investigation, and computational molecular modeling

    PubMed Central

    Ashraf, Zaman; Alamgeer; Kanwal, Munazza; Hassan, Mubashir; Abdullah, Sahar; Waheed, Mamuna; Ahsan, Haseeb; Kim, Song Ja

    2016-01-01

    Flurbiprofen–antioxidant mutual prodrugs were synthesized to reduce the gastrointestinal (GI) effects associated with flurbiprofen. For reducing the GI toxicity, the free carboxylic group (–COOH) was temporarily masked by esterification with phenolic –OH of natural antioxidants vanillin, thymol, umbelliferone, and sesamol. The in vitro hydrolysis of synthesized prodrugs showed that they were stable in buffer solution at pH 1.2, indicating their stability in the stomach. The synthesized prodrugs undergo significant hydrolysis in 80% human plasma and thus release free flurbiprofen. The minimum reversion was observed at pH 1.2, suggesting that prodrugs are less irritating to the stomach than flurbiprofen. The anti-inflammatory, analgesic, antipyretic, and ulcerogenic activities of prodrugs were evaluated. All the synthesized prodrugs significantly (P<0.001) reduced the inflammation against carrageenan and egg albumin-induced paw edema at 4 hours of study. The reduction in the size of the inflamed paw showed that most of the compounds inhibited the later phase of inflammation. The prodrug 2-oxo-2H-chromen-7-yl-2-(2-fluorobiphenyl-4-yl)propanoate (4b) showed significant reduction in paw licking with percentage inhibition of 58%. It also exhibited higher analgesic activity, reducing the number of writhes with a percentage of 75%, whereas flurbiprofen showed 69% inhibition. Antipyretic activity was investigated using brewer’s yeast-induced pyrexia model, and significant (P<0.001) reduction in rectal temperature was shown by all prodrugs at all times of assessment. The results of ulcerogenic activity showed that all prodrugs produced less GI irritation than flurbiprofen. Molecular docking and simulation studies were carried out with cyclooxygenase (COX-1 and COX-2) proteins, and it was observed that our prodrugs have more potential to selectively bind to COX-2 than to COX-1. It is concluded that the synthesized prodrugs have promising pharmacological activities

  9. Mutual inhibition of insulin signaling and PHLPP-1 determines cardioprotective efficiency of Akt in aged heart.

    PubMed

    Xing, Yuan; Sun, Wanqing; Wang, Yishi; Gao, Feng; Ma, Heng

    2016-05-01

    Insulin protects cardiomyocytes from myocardial ischemia/reperfusion (MI/R) injury through activating Akt. However, phosphatase PHLPP-1 (PH domain leucine-rich repeat protein phosphatase-1) dephosphorylates and inactivates Akt. The balanced competitive interaction of insulin and PHLPP-1 has not been directly examined. In this study, we have identified the effect of mutual inhibition of insulin signaling and PHLPP-1 on the cardioprotective efficiency of Akt in aged heart. Young (3 months) and aged (20 months) Sprague Dawley (SD) rats were subjected to MI/Rin vivo. The PHLPP-1 level was higher in aged vs. young hearts at base. But, insulin treatment failed to decrease PHLPP-1 level during reperfusion in the aged hearts. Consequently, the cardioprotection of insulin-induced Akt activation was impaired in aged hearts, resulting in more susceptible to MI/R injury. In cultured rat ventricular myocytes, PHLPP-1 knockdown significantly enhanced insulin-induced Akt phosphorylation and reduced simulated hypoxia/reoxygenation-induced apoptosis. Contrary, PHLPP-1 overexpression terminated Akt phosphorylation and deteriorated myocytes apoptosis. Using in vivo aged animal models, we confirmed that cardiac PHLPP-1 knockdown or enhanced insulin sensitivity by exercise training dramatically increased insulin-induced Akt phosphorylation. Specifically, MI/R-induced cardiomyocyte apoptosis and infarct size were decreased and cardiac function was increased. More importantly, we found that insulin regulated the degradation of PHLPP-1 and insulin treatment could enhance the binding between PHLPP-1 and β-transducin repeat-containing protein (β-TrCP) to target for ubiquitin-dependent degradation. Altogether, we have identified a new mechanism by which insulin suppresses PHLPP-1 to enhance Akt activation. But, aged heart possesses lower insulin effectiveness and fails to decrease PHLPP-1 during MI/R, which subsequently limited Akt activity and cardioprotection. PHLPP-1 could be a

  10. Mutual inhibition of insulin signaling and PHLPP-1 determines cardioprotective efficiency of Akt in aged heart

    PubMed Central

    Xing, Yuan; Sun, Wanqing; Wang, Yishi; Gao, Feng; Ma, Heng

    2016-01-01

    Insulin protects cardiomyocytes from myocardial ischemia/reperfusion (MI/R) injury through activating Akt. However, phosphatase PHLPP-1 (PH domain leucine-rich repeat protein phosphatase-1) dephosphorylates and inactivates Akt. The balanced competitive interaction of insulin and PHLPP-1 has not been directly examined. In this study, we have identified the effect of mutual inhibition of insulin signaling and PHLPP-1 on the cardioprotective efficiency of Akt in aged heart. Young (3 mon) and aged (20 mon) Sprague Dawley (SD) rats were subjected to MI/R in vivo. The PHLPP-1 level was higher in aged vs. young hearts at base. But, insulin treatment failed to decrease PHLPP-1 level during reperfusion in the aged hearts. Consequently, the cardioprotection of insulin-induced Akt activation was impaired in aged hearts, resulting in more susceptible to MI/R injury. In cultured rat ventricular myocytes, PHLPP-1 knockdown significantly enhanced insulin-induced Akt phosphorylation and reduced simulated hypoxia/reoxygenation-induced apoptosis. Contrary, PHLPP-1 overexpression terminated Akt phosphorylation and deteriorated myocytes apoptosis. Using in vivo aged animal models, we confirmed that cardiac PHLPP-1 knockdown or enhanced insulin sensitivity by exercise training dramatically increased insulin-induced Akt phosphorylation. Specifically, MI/R-induced cardiomyocyte apoptosis and infarct size were decreased and cardiac function was increased. More importantly, we found that insulin regulated the degradation of PHLPP-1 and insulin treatment could enhance the binding between PHLPP-1 and β-transducin repeat-containing protein (β-TrCP) to target for ubiquitin-dependent degradation. Altogether, we have identified a new mechanism by which insulin suppresses PHLPP-1 to enhance Akt activation. But, aged heart possesses lower insulin effectiveness and fails to decrease PHLPP-1 during MI/R, which subsequently limited Akt activity and cardioprotection. PHLPP-1 could be a promising

  11. Mathematical Models for Sleep-Wake Dynamics: Comparison of the Two-Process Model and a Mutual Inhibition Neuronal Model

    PubMed Central

    Skeldon, Anne C.; Dijk, Derk-Jan; Derks, Gianne

    2014-01-01

    Sleep is essential for the maintenance of the brain and the body, yet many features of sleep are poorly understood and mathematical models are an important tool for probing proposed biological mechanisms. The most well-known mathematical model of sleep regulation, the two-process model, models the sleep-wake cycle by two oscillators: a circadian oscillator and a homeostatic oscillator. An alternative, more recent, model considers the mutual inhibition of sleep promoting neurons and the ascending arousal system regulated by homeostatic and circadian processes. Here we show there are fundamental similarities between these two models. The implications are illustrated with two important sleep-wake phenomena. Firstly, we show that in the two-process model, transitions between different numbers of daily sleep episodes can be classified as grazing bifurcations. This provides the theoretical underpinning for numerical results showing that the sleep patterns of many mammals can be explained by the mutual inhibition model. Secondly, we show that when sleep deprivation disrupts the sleep-wake cycle, ostensibly different measures of sleepiness in the two models are closely related. The demonstration of the mathematical similarities of the two models is valuable because not only does it allow some features of the two-process model to be interpreted physiologically but it also means that knowledge gained from study of the two-process model can be used to inform understanding of the behaviour of the mutual inhibition model. This is important because the mutual inhibition model and its extensions are increasingly being used as a tool to understand a diverse range of sleep-wake phenomena such as the design of optimal shift-patterns, yet the values it uses for parameters associated with the circadian and homeostatic processes are very different from those that have been experimentally measured in the context of the two-process model. PMID:25084361

  12. Inhibition of immune functions by antiviral drugs.

    PubMed Central

    Heagy, W; Crumpacker, C; Lopez, P A; Finberg, R W

    1991-01-01

    Immune functions were evaluated in vitro for PBMC isolated from healthy donors and cultured with the antiviral agents, 3'-azido-3'-deoxythymidine (AZT), ribavirin, ganciclovir, 2'3'-dideoxyinosine (ddI), or acyclovir. To identify methods for assessing the effects of antiviral drugs on immune cells, the PBMC response to mitogens, Con A, or phytohemagglutinin was evaluated from measurements of [3H]thymidine and [14C]-leucine incorporation, cell growth, cellular RNA, DNA, and protein levels, and the PBMC proliferative cycle (i.e., progression from G0----G1----S----G2 + M). At clinically relevant concentrations, AZT, ribavirin, or ganciclovir diminished PBMC responsiveness to mitogen. The numbers of proliferating cells in G1, S, and G2 + M phases of the cell cycle, DNA content, and [3H]thymidine uptake were decreased in cultures treated with AZT, ribavirin, or ganciclovir. AZT or ribavirin but not ganciclovir reduced RNA and protein in the cultures and inhibited cell growth. Whereas AZT, ribavirin, or ganciclovir were antiproliferative, ddI or acyclovir had little, if any, effect on PBMC mitogenesis. The inhibitory effects of antivirals on immune cells may contribute to the immune deterioration observed in patients following prolonged use of the drugs. PMID:1904068

  13. Reliable Attention Network Scores and Mutually Inhibited Inter-network Relationships Revealed by Mixed Design and Non-orthogonal Method

    PubMed Central

    Wang, Yi-Feng; Jing, Xiu-Juan; Liu, Feng; Li, Mei-Ling; Long, Zhi-Liang; Yan, Jin H.; Chen, Hua-Fu

    2015-01-01

    The attention system can be divided into alerting, orienting, and executive control networks. The efficiency and independence of attention networks have been widely tested with the attention network test (ANT) and its revised versions. However, many studies have failed to find effects of attention network scores (ANSs) and inter-network relationships (INRs). Moreover, the low reliability of ANSs can not meet the demands of theoretical and empirical investigations. Two methodological factors (the inter-trial influence in the event-related design and the inter-network interference in orthogonal contrast) may be responsible for the unreliability of ANT. In this study, we combined the mixed design and non-orthogonal method to explore ANSs and directional INRs. With a small number of trials, we obtained reliable and independent ANSs (split-half reliability of alerting: 0.684; orienting: 0.588; and executive control: 0.616), suggesting an individual and specific attention system. Furthermore, mutual inhibition was observed when two networks were operated simultaneously, indicating a differentiated but integrated attention system. Overall, the reliable and individual specific ANSs and mutually inhibited INRs provide novel insight into the understanding of the developmental, physiological and pathological mechanisms of attention networks, and can benefit future experimental and clinical investigations of attention using ANT. PMID:25997025

  14. Evaluation of Mutual Drug-Drug Interaction within Geneva Cocktail for Cytochrome P450 Phenotyping using Innovative Dried Blood Sampling Method.

    PubMed

    Bosilkovska, Marija; Samer, Caroline; Déglon, Julien; Thomas, Aurélien; Walder, Bernhard; Desmeules, Jules; Daali, Youssef

    2016-09-01

    Cytochrome P450 (CYP) activity can be assessed using a 'cocktail' phenotyping approach. Recently, we have developed a cocktail (Geneva cocktail) which combines the use of low-dose probes with a low-invasiveness dried blood spots (DBS) sampling technique and a single analytical method for the phenotyping of six major CYP isoforms. We have previously demonstrated that modulation of CYP activity after pre-treatment with CYP inhibitors/inducer could be reliably predicted using Geneva cocktail. To further validate this cocktail, in this study, we have verified whether probe drugs contained in the latter cause mutual drug-drug interactions. In a randomized, four-way, Latin-square crossover study, 30 healthy volunteers received low-dose caffeine, flurbiprofen, omeprazole, dextromethorphan and midazolam (a previously validated combination with no mutual drug-drug interactions); fexofenadine alone; bupropion alone; or all seven drugs simultaneously (Geneva cocktail). Pharmacokinetic profiles of the probe drugs and their metabolites were determined in DBS samples using both conventional micropipette sampling and new microfluidic device allowing for self-sampling. The 90% confidence intervals for the geometric mean ratios of AUC metabolite/AUC probe for CYP probes administered alone or within Geneva cocktail fell within the 0.8-1.25 bioequivalence range indicating the absence of pharmacokinetic interaction. The same result was observed for the chosen phenotyping indices, that is metabolic ratios at 2 hr (CYP1A2, CYP3A) or 3 hr (CYP2B6, CYP2C9, CYP2C19, CYP2D6) post-cocktail administration. DBS sampling could successfully be performed using a new microfluidic device. In conclusion, Geneva cocktail combined with an innovative DBS sampling device can be used routinely as a test for simultaneous CYP phenotyping. PMID:27009433

  15. Inhibition of 5-methyltetrahydrofolic acid transport by amphipathic drugs.

    PubMed

    Branda, R F; Nelson, N L

    1981-01-01

    Numerous chemically unrelated drugs after the membrane transport of folate compounds. To investigate drug structure-activity relationships, we measured the effect of amphipathic drugs (that is, compounds with polar-apolar character) on 5-methyltetrahydrofolic acid permeability of human erythrocytes. All drugs tested were inhibitory, but only compounds that exist at least partially in the anionic form were highly active. Ethacrynic acid, sulfinpyrazone, phenylbutazone, sulfasalazine, and furosemide were effective transport inhibitors in micromolar concentrations. In contrast, compounds that are capable of forming cations at physiologic pH, such as chlorpromazine, procaine, tetracaine, and papaverine, were inhibitory only in millimolar concentrations or caused hemolysis before major inhibition was seen. Inhibitory activity correlated with drug dissociation constant (r = 0.87). A double-reciprocal plot analysis of drug effect on 5-methyltetrahydrofolic acid transport showed changes in both Km and Vmax (indicating a mixture of competitive and noncompetitive inhibition) by ethacrynic acid, sulfasalazine, and phlorizin. Inhibitory activity of a series of eight phenoxyacetic derivatives, including ethacrynic acid, correlated highly with measurements of liposolubility (r = 0.87) but only weakly with the Hammet substituent constant (r = 0.56). These results suggest that the effect of amphipathic drugs on 5-methyltetrahydrofolic acid transport is influenced by drug pKa and by the presence of hydrophobic substituents, but is relatively independent of electron-attracting groups. PMID:6926815

  16. Computational Analysis of an Autophagy/Translation Switch Based on Mutual Inhibition of MTORC1 and ULK1

    PubMed Central

    Szymańska, Paulina; Martin, Katie R.; MacKeigan, Jeffrey P.; Hlavacek, William S.; Lipniacki, Tomasz

    2015-01-01

    We constructed a mechanistic, computational model for regulation of (macro)autophagy and protein synthesis (at the level of translation). The model was formulated to study the system-level consequences of interactions among the following proteins: two key components of MTOR complex 1 (MTORC1), namely the protein kinase MTOR (mechanistic target of rapamycin) and the scaffold protein RPTOR; the autophagy-initiating protein kinase ULK1; and the multimeric energy-sensing AMP-activated protein kinase (AMPK). Inputs of the model include intrinsic AMPK kinase activity, which is taken as an adjustable surrogate parameter for cellular energy level or AMP:ATP ratio, and rapamycin dose, which controls MTORC1 activity. Outputs of the model include the phosphorylation level of the translational repressor EIF4EBP1, a substrate of MTORC1, and the phosphorylation level of AMBRA1 (activating molecule in BECN1-regulated autophagy), a substrate of ULK1 critical for autophagosome formation. The model incorporates reciprocal regulation of mTORC1 and ULK1 by AMPK, mutual inhibition of MTORC1 and ULK1, and ULK1-mediated negative feedback regulation of AMPK. Through analysis of the model, we find that these processes may be responsible, depending on conditions, for graded responses to stress inputs, for bistable switching between autophagy and protein synthesis, or relaxation oscillations, comprising alternating periods of autophagy and protein synthesis. A sensitivity analysis indicates that the prediction of oscillatory behavior is robust to changes of the parameter values of the model. The model provides testable predictions about the behavior of the AMPK-MTORC1-ULK1 network, which plays a central role in maintaining cellular energy and nutrient homeostasis. PMID:25761126

  17. Computational analysis of an autophagy/translation switch based on mutual inhibition of MTORC1 and ULK1

    DOE PAGESBeta

    Szymańska, Paulina; Martin, Katie R.; MacKeigan, Jeffrey P.; Hlavacek, William S.; Lipniacki, Tomasz

    2015-03-11

    We constructed a mechanistic, computational model for regulation of (macro)autophagy and protein synthesis (at the level of translation). The model was formulated to study the system-level consequences of interactions among the following proteins: two key components of MTOR complex 1 (MTORC1), namely the protein kinase MTOR (mechanistic target of rapamycin) and the scaffold protein RPTOR; the autophagy-initiating protein kinase ULK1; and the multimeric energy-sensing AMP-activated protein kinase (AMPK). Inputs of the model include intrinsic AMPK kinase activity, which is taken as an adjustable surrogate parameter for cellular energy level or AMP:ATP ratio, and rapamycin dose, which controls MTORC1 activity. Outputsmore » of the model include the phosphorylation level of the translational repressor EIF4EBP1, a substrate of MTORC1, and the phosphorylation level of AMBRA1 (activating molecule in BECN1-regulated autophagy), a substrate of ULK1 critical for autophagosome formation. The model incorporates reciprocal regulation of mTORC1 and ULK1 by AMPK, mutual inhibition of MTORC1 and ULK1, and ULK1-mediated negative feedback regulation of AMPK. Through analysis of the model, we find that these processes may be responsible, depending on conditions, for graded responses to stress inputs, for bistable switching between autophagy and protein synthesis, or relaxation oscillations, comprising alternating periods of autophagy and protein synthesis. A sensitivity analysis indicates that the prediction of oscillatory behavior is robust to changes of the parameter values of the model. The model provides testable predictions about the behavior of the AMPK-MTORC1-ULK1 network, which plays a central role in maintaining cellular energy and nutrient homeostasis.« less

  18. Computational analysis of an autophagy/translation switch based on mutual inhibition of MTORC1 and ULK1

    SciTech Connect

    Szymańska, Paulina; Martin, Katie R.; MacKeigan, Jeffrey P.; Hlavacek, William S.; Lipniacki, Tomasz

    2015-03-11

    We constructed a mechanistic, computational model for regulation of (macro)autophagy and protein synthesis (at the level of translation). The model was formulated to study the system-level consequences of interactions among the following proteins: two key components of MTOR complex 1 (MTORC1), namely the protein kinase MTOR (mechanistic target of rapamycin) and the scaffold protein RPTOR; the autophagy-initiating protein kinase ULK1; and the multimeric energy-sensing AMP-activated protein kinase (AMPK). Inputs of the model include intrinsic AMPK kinase activity, which is taken as an adjustable surrogate parameter for cellular energy level or AMP:ATP ratio, and rapamycin dose, which controls MTORC1 activity. Outputs of the model include the phosphorylation level of the translational repressor EIF4EBP1, a substrate of MTORC1, and the phosphorylation level of AMBRA1 (activating molecule in BECN1-regulated autophagy), a substrate of ULK1 critical for autophagosome formation. The model incorporates reciprocal regulation of mTORC1 and ULK1 by AMPK, mutual inhibition of MTORC1 and ULK1, and ULK1-mediated negative feedback regulation of AMPK. Through analysis of the model, we find that these processes may be responsible, depending on conditions, for graded responses to stress inputs, for bistable switching between autophagy and protein synthesis, or relaxation oscillations, comprising alternating periods of autophagy and protein synthesis. A sensitivity analysis indicates that the prediction of oscillatory behavior is robust to changes of the parameter values of the model. The model provides testable predictions about the behavior of the AMPK-MTORC1-ULK1 network, which plays a central role in maintaining cellular energy and nutrient homeostasis.

  19. Drug-Eluting Fibers for HIV-1 Inhibition and Contraception

    PubMed Central

    Ball, Cameron; Krogstad, Emily; Chaowanachan, Thanyanan; Woodrow, Kim A.

    2012-01-01

    Multipurpose prevention technologies (MPTs) that simultaneously prevent sexually transmitted infections (STIs) and unintended pregnancy are a global health priority. Combining chemical and physical barriers offers the greatest potential to design effective MPTs, but integrating both functional modalities into a single device has been challenging. Here we show that drug-eluting fiber meshes designed for topical drug delivery can function as a combination chemical and physical barrier MPT. Using FDA-approved polymers, we fabricated nanofiber meshes with tunable fiber size and controlled degradation kinetics that facilitate simultaneous release of multiple agents against HIV-1, HSV-2, and sperm. We observed that drug-loaded meshes inhibited HIV-1 infection in vitro and physically obstructed sperm penetration. Furthermore, we report on a previously unknown activity of glycerol monolaurate (GML) to potently inhibit sperm motility and viability. The application of drug-eluting nanofibers for HIV-1 prevention and sperm inhibition may serve as an innovative platform technology for drug delivery to the lower female reproductive tract. PMID:23209601

  20. Drug-eluting fibers for HIV-1 inhibition and contraception.

    PubMed

    Ball, Cameron; Krogstad, Emily; Chaowanachan, Thanyanan; Woodrow, Kim A

    2012-01-01

    Multipurpose prevention technologies (MPTs) that simultaneously prevent sexually transmitted infections (STIs) and unintended pregnancy are a global health priority. Combining chemical and physical barriers offers the greatest potential to design effective MPTs, but integrating both functional modalities into a single device has been challenging. Here we show that drug-eluting fiber meshes designed for topical drug delivery can function as a combination chemical and physical barrier MPT. Using FDA-approved polymers, we fabricated nanofiber meshes with tunable fiber size and controlled degradation kinetics that facilitate simultaneous release of multiple agents against HIV-1, HSV-2, and sperm. We observed that drug-loaded meshes inhibited HIV-1 infection in vitro and physically obstructed sperm penetration. Furthermore, we report on a previously unknown activity of glycerol monolaurate (GML) to potently inhibit sperm motility and viability. The application of drug-eluting nanofibers for HIV-1 prevention and sperm inhibition may serve as an innovative platform technology for drug delivery to the lower female reproductive tract. PMID:23209601

  1. Flagging Drugs That Inhibit the Bile Salt Export Pump.

    PubMed

    Montanari, Floriane; Pinto, Marta; Khunweeraphong, Narakorn; Wlcek, Katrin; Sohail, M Imran; Noeske, Tobias; Boyer, Scott; Chiba, Peter; Stieger, Bruno; Kuchler, Karl; Ecker, Gerhard F

    2016-01-01

    The bile salt export pump (BSEP) is an ABC-transporter expressed at the canalicular membrane of hepatocytes. Its physiological role is to expel bile salts into the canaliculi from where they drain into the bile duct. Inhibition of this transporter may lead to intrahepatic cholestasis. Predictive computational models of BSEP inhibition may allow for fast identification of potentially harmful compounds in large databases. This article presents a predictive in silico model based on physicochemical descriptors that is able to flag compounds as potential BSEP inhibitors. This model was built using a training set of 670 compounds with available BSEP inhibition potencies. It successfully predicted BSEP inhibition for two independent test sets and was in a further step used for a virtual screening experiment. After in vitro testing of selected candidates, a marketed drug, bromocriptin, was identified for the first time as BSEP inhibitor. This demonstrates the usefulness of the model to identify new BSEP inhibitors and therefore potential cholestasis perpetrators. PMID:26642869

  2. 5-Aminosalicylic Acid Azo-Linked to Procainamide Acts as an Anticolitic Mutual Prodrug via Additive Inhibition of Nuclear Factor kappaB.

    PubMed

    Kim, Wooseong; Nam, Joon; Lee, Sunyoung; Jeong, Seongkeun; Jung, Yunjin

    2016-06-01

    To improve the anticolitic efficacy of 5-aminosalicylic acid (5-ASA), a colon-specific mutual prodrug of 5-ASA was designed. 5-ASA was coupled to procainamide (PA), a local anesthetic, via an azo bond to prepare 5-(4-{[2-(diethylamino)ethyl]carbamoyl}phenylazo)salicylic acid (5-ASA-azo-PA). 5-ASA-azo-PA was cleaved to 5-ASA and PA up to about 76% at 10 h in the cecal contents while remaining stable in the small intestinal contents. Oral gavage of 5-ASA-azo-PA and sulfasalazine, a colon-specific prodrug currently used in clinic, to rats showed similar efficiency in delivery of 5-ASA to the large intestine, and PA was not detectable in the blood after 5-ASA-azo-PA administration. Oral gavage of 5-ASA-azo-PA alleviated 2,4,6-trinitrobenzenesulfonic acid-induced rat colitis. Moreover, combined intracolonic treatment with 5-ASA and PA elicited an additive ameliorative effect. Furthermore, combined treatment with 5-ASA and PA additively inhibited nuclear factor-kappaB (NFκB) activity in human colon carcinoma cells and inflamed colonic tissues. Finally, 5-ASA-azo-PA administered orally was able to reduce inflammatory mediators, NFκB target gene products, in the inflamed colon. 5-ASA-azo-PA may be a colon-specific mutual prodrug acting against colitis, and the mutual anticolitic effects occurred at least partly through the cooperative inhibition of NFκB activity. PMID:27112518

  3. Inhibition of recombinant Pneumocystis carinii dihydropteroate synthetase by sulfa drugs.

    PubMed Central

    Hong, Y L; Hossler, P A; Calhoun, D H; Meshnick, S R

    1995-01-01

    Forty-four sulfa drugs were screened against crude preparations of recombinant Pneumocystis carinii dihydropteroate synthetase. The apparent Michaelis-Menten constants (Km) for p-aminobenzoic acid and 7,8-dihydro-6-hydroxymethylpterin pyrophosphate were 0.34 +/- 0.02 and 2.50 +/- 0.71 microM, respectively. Several sulfa drugs, including sulfathiazole, sulfachlorpyridazine, sulfamethoxypyridazine, and sulfathiourea, inhibited dihydropteroate synthetase approximately as well as sulfamethoxazole, as determined by the concentrations which cause 50% inhibition and/or by Ki. For all sulfones and sulfonamides tested, unsubstituted p-amino groups were necessary for activity, and sulfonamides containing an N1-heterocyclic substituent were found to be the most effective inhibitors. Folate biosynthesis in isolated intact P. carinii was approximately equally sensitive to inhibition by sulfamethoxazole, sulfachlorpyridazine, sulfamethoxypyridazine, sulfisoxazole, and sulfathiazole. Two of these drugs, sulfamethoxypyridazine and sulfisoxazole, are known to be less toxic than sulfamethoxazole and should be further evaluated for the treatment of P. carinii pneumonia. PMID:7486915

  4. Nanodrug Formed by Coassembly of Dual Anticancer Drugs to Inhibit Cancer Cell Drug Resistance.

    PubMed

    Zhao, Yuanyuan; Chen, Fei; Pan, Yuanming; Li, Zhipeng; Xue, Xiangdong; Okeke, Chukwunweike Ikechukwu; Wang, Yifeng; Li, Chan; Peng, Ling; Wang, Paul C; Ma, Xiaowei; Liang, Xing-Jie

    2015-09-01

    Carrier-free pure nanodrugs (PNDs) that are composed entirely of pharmaceutically active molecules are regarded as promising candidates to be the next generation of drug formulations and are mainly formulated from supramolecular self-assembly of drug molecules. It benefits from the efficient use of drug compounds with poor aqueous solubility and takes advantage of nanoscale drug delivery systems. Here, a type of all-in-one nanoparticle consisting of multiple drugs with enhanced synergistic antiproliferation efficiency against drug-resistant cancer cells has been created. To nanoparticulate the anticancer drugs, 10-hydroxycamptothecin (HCPT) and doxorubicin (DOX) were chosen as a typical model. The resulting HD nanoparticles (HD NPs) were formulated by a "green" and convenient self-assembling method, and the water-solubility of 10-hydroxycamptothecin (HCPT) was improved 50-fold after nanosizing by coassembly with DOX. The formation process was studied by observing the morphological changes at various reaction times and molar ratios of DOX to HCPT. Molecular dynamics (MD) simulations showed that DOX molecules tend to assemble around HCPT molecules through intermolecular forces. With the advantage of nanosizing, HD NPs could improve the intracellular drug retention of DOX to as much as 2-fold in drug-resistant cancer cells (MCF-7R). As a dual-drug-loaded nanoformulation, HD NPs effectively enhanced drug cytotoxicity to drug-resistant cancer cells. The combination of HCPT and DOX exhibited a synergistic effect as the nanosized HD NPs improved drug retention in drug-resistant cancer cells against P-gp efflux in MCF-7R cells. Furthermore, colony forming assays were applied to evaluate long-term inhibition of cancer cell proliferation, and these assays confirmed the greatly improved cytotoxicity of HD NPs in drug-resistant cells compared to free drugs. PMID:26270258

  5. Nanodrug Formed by Coassembly of Dual Anticancer Drugs to Inhibit Cancer Cell Drug Resistance

    PubMed Central

    Zhao, Yuanyuan; Chen, Fei; Pan, Yuanming; Li, Zhipeng; Xue, Xiangdong; Okeke, Chukwunweike Ikechukwu; Wang, Yifeng; Li, Chan; Peng, Ling; Wang, Paul C.; Ma, Xiaowei; Liang, Xing-Jie

    2016-01-01

    Carrier-free pure nanodrugs (PNDs) that are composed entirely of pharmaceutically active molecules are regarded as promising candidates to be the next generation of drug formulations and are mainly formulated from supramolecular self-assembly of drug molecules. It benefits from the efficient use of drug compounds with poor aqueous solubility and takes advantage of nanoscale drug delivery systems. Here, a type of all-in-one nanoparticle consisting of multiple drugs with enhanced synergistic antiproliferation efficiency against drug-resistant cancer cells has been created. To nanoparticulate the anticancer drugs, 10-hydroxycamptothecin (HCPT) and doxorubicin (DOX) were chosen as a typical model. The resulting HD nanoparticles (HD NPs) were formulated by a “green” and convenient self-assembling method, and the water-solubility of 10-hydroxycamptothecin (HCPT) was improved 50-fold after nanosizing by coassembly with DOX. The formation process was studied by observing the morphological changes at various reaction times and molar ratios of DOX to HCPT. Molecular dynamics (MD) simulations showed that DOX molecules tend to assemble around HCPT molecules through intermolecular forces. With the advantage of nanosizing, HD NPs could improve the intracellular drug retention of DOX to as much as 2-fold in drug-resistant cancer cells (MCF-7R). As a dual-drug-loaded nanoformulation, HD NPs effectively enhanced drug cytotoxicity to drug-resistant cancer cells. The combination of HCPT and DOX exhibited a synergistic effect as the nanosized HD NPs improved drug retention in drug-resistant cancer cells against P-gp efflux in MCF-7R cells. Furthermore, colony forming assays were applied to evaluate long-term inhibition of cancer cell proliferation, and these assays confirmed the greatly improved cytotoxicity of HD NPs in drug-resistant cells compared to free drugs. PMID:26270258

  6. The role of metabolites in predicting drug-drug interactions: Focus on irreversible P450 inhibition

    PubMed Central

    VandenBrink, Brooke M.; Isoherranen, Nina

    2010-01-01

    Irreversible inhibition of cytochrome P450 enzymes can cause significant drug-drug interactions (DDIs). Formation of metabolites is fundamental for the inactivation of P450 enzymes. Of the 19 inactivators with a known mechanism of inactivation, 10 have circulating metabolites that are known to be on path to inactive P450. The fact that inactivation usually requires multiple metabolic steps implies that predicting in vivo interactions may require complex models, and in vitro data generated from each metabolite. The data reviewed here suggest that circulating metabolites are much more important in in vivo P450 inhibition than is currently acknowledged. PMID:20047147

  7. Pharmacological telomerase inhibition can sensitize drug-resistant and drug-sensitive cells to chemotherapeutic treatment.

    PubMed

    Ward, Ryan J; Autexier, Chantal

    2005-09-01

    Effective strategies to reverse or prevent chemotherapeutic resistance are required before cancer therapies can be curative. Telomerase is the ribonucleoprotein responsible for de novo synthesis and maintenance of telomeres, and its activity is predominantly observed in cancer cells. The telomerase enzyme has been successfully inhibited or inactivated to sensitize cells to cellular stresses; however, no studies have determined yet the effect of combining a pharmacological inhibitor of telomerase catalysis and traditional chemotherapeutics for the treatment of drug-sensitive or drug-resistant cancers. Here, we describe the effect of 2-[(E)-3-naphtalen-2-yl-but-2-enoylamino]-benzoic acid (BIBR1532), a small-molecule inhibitor of telomerase catalytic activity, on drug-resistant leukemia and breast cancer cells and their parental counterparts when treated in combination with chemotherapeutics. We observed that BIBR1532-treated cells show progressive telomere shortening, decreased proliferative capacity, and sensitization to chemotherapeutic treatment. These effects are telomere length-dependent, because cells insensitive to BIBR1532 or cells released from telomerase inhibition did not demonstrate changes in growth ability or drug sensitivity. Our novel observations suggest that pharmacological telomerase inhibition in combination therapy may be a valid strategy for the treatment of both drug-sensitive and drug-resistant cancers. PMID:15939802

  8. Pharmacological diversity among drugs that inhibit bone resorption.

    PubMed

    Russell, R Graham G

    2015-06-01

    Drugs that inhibit bone resorption ('anti-resorptives') continue to dominate the therapy of bone diseases characterized by enhanced bone destruction, including Paget's disease, osteoporosis and cancers. The historic use of oestrogens for osteoporosis led on to SERMs (Selective Estrogen Receptor Modulators, e.g. raloxifene and bazedoxifene). Currently the mainstay of treatment worldwide is still with bisphosphonates, as used clinically for over 40 years. The more recently introduced anti-RANK-ligand antibody, denosumab, is also very effective in reducing vertebral, non-vertebral and hip fractures. Odanacatib is the only cathepsin K inhibitor likely to be registered for clinical use. The pharmacological basis for the action of each of these drug classes is different, enabling choices to be made to ensure their optimal use in clinical practice. PMID:26048735

  9. Alleviating Cancer Drug Toxicity by Inhibiting a Bacterial Enzyme

    SciTech Connect

    Wallace, Bret D.; Wang, Hongwei; Lane, Kimberly T.; Scott, John E.; Orans, Jillian; Koo, Ja Seol; Venkatesh, Madhukumar; Jobin, Christian; Yeh, Li-An; Mani, Sridhar; Redinbo, Matthew R.

    2011-08-12

    The dose-limiting side effect of the common colon cancer chemotherapeutic CPT-11 is severe diarrhea caused by symbiotic bacterial {beta}-glucuronidases that reactivate the drug in the gut. We sought to target these enzymes without killing the commensal bacteria essential for human health. Potent bacterial {beta}-glucuronidase inhibitors were identified by high-throughput screening and shown to have no effect on the orthologous mammalian enzyme. Crystal structures established that selectivity was based on a loop unique to bacterial {beta}-glucuronidases. Inhibitors were highly effective against the enzyme target in living aerobic and anaerobic bacteria, but did not kill the bacteria or harm mammalian cells. Finally, oral administration of an inhibitor protected mice from CPT-11-induced toxicity. Thus, drugs may be designed to inhibit undesirable enzyme activities in essential microbial symbiotes to enhance chemotherapeutic efficacy.

  10. The Synthetic Antiviral Drug Arbidol Inhibits Globally Prevalent Pathogenic Viruses

    PubMed Central

    Pécheur, Eve-Isabelle; Borisevich, Viktoriya; Halfmann, Peter; Morrey, John D.; Smee, Donald F.; Prichard, Mark; Mire, Chad E.; Kawaoka, Yoshihiro; Geisbert, Thomas W.

    2016-01-01

    ABSTRACT Arbidol (ARB) is a synthetic antiviral originally developed to combat influenza viruses. ARB is currently used clinically in several countries but not in North America. We have previously shown that ARB inhibits in vitro hepatitis C virus (HCV) by blocking HCV entry and replication. In this report, we expand the list of viruses that are inhibited by ARB and demonstrate that ARB suppresses in vitro infection of mammalian cells with Ebola virus (EBOV), Tacaribe arenavirus, and human herpesvirus 8 (HHV-8). We also confirm suppression of hepatitis B virus and poliovirus by ARB. ARB inhibited EBOV Zaire Kikwit infection when added before or at the same time as virus infection and was less effective when added 24 h after EBOV infection. Experiments with recombinant vesicular stomatitis virus (VSV) expressing the EBOV Zaire glycoprotein showed that infection was inhibited by ARB at early stages, most likely at the level of viral entry into host cells. ARB inhibited HHV-8 replication to a similar degree as cidofovir. Our data broaden the spectrum of antiviral efficacy of ARB to include globally prevalent viruses that cause significant morbidity and mortality. IMPORTANCE There are many globally prevalent viruses for which there are no licensed vaccines or antiviral medicines. Some of these viruses, such as Ebola virus or members of the arenavirus family, rapidly cause severe hemorrhagic diseases that can be fatal. Other viruses, such as hepatitis B virus or human herpesvirus 8 (HHV-8), establish persistent infections that cause chronic illnesses, including cancer. Thus, finding an affordable, effective, and safe drug that blocks many viruses remains an unmet medical need. The antiviral drug arbidol (ARB), already in clinical use in several countries as an anti-influenza treatment, has been previously shown to suppress the growth of many viruses. In this report, we expand the list of viruses that are blocked by ARB in a laboratory setting to include Ebola virus

  11. Binding and inhibition of drug transport proteins by heparin

    PubMed Central

    Chen, Yunliang; Scully, Michael; Petralia, Gloria; Kakkar, Ajay

    2014-01-01

    A major problem in cancer treatment is the development of resistance to chemotherapeutic agents, multidrug resistance (MDR), associated with increased activity of transmembrane drug transporter proteins which impair cytotoxic treatment by rapidly removing the drugs from the targeted cells. Previously, it has been shown that heparin treatment of cancer patients undergoing chemotherapy increases survival. In order to determine whether heparin is capable reducing MDR and increasing the potency of chemotherapeutic drugs, the cytoxicity of a number of agents toward four cancer cell lines (a human enriched breast cancer stem cell line, two human breast cancer cell lines, MCF-7 and MDA-MB-231, and a human lung cancer cell line A549) was tested in the presence or absence of heparin. Results demonstrated that heparin increased the cytotoxicity of a range of chemotherapeutic agents. This effect was associated with the ability of heparin to bind to several of the drug transport proteins of the ABC and non ABC transporter systems. Among the ABC system, heparin treatment caused significant inhibition of the ATPase activity of ABCG2 and ABCC1, and of the efflux function observed as enhanced intracellular accumulation of specific substrates. Doxorubicin cytoxicity, which was enhanced by heparin treatment of MCF-7 cells, was found to be under the control of one of the major non-ABC transporter proteins, lung resistance protein (LRP). LRP was also shown to be a heparin-binding protein. These findings indicate that heparin has a potential role in the clinic as a drug transporter modulator to reduce multidrug resistance in cancer patients. PMID:24253450

  12. The Involvement of Mutual Inhibition of ERK and mTOR in PLCγ1-Mediated MMP-13 Expression in Human Osteoarthritis Chondrocytes

    PubMed Central

    Liu, Zejun; Cai, Heguo; Zheng, Xinpeng; Zhang, Bing; Xia, Chun

    2015-01-01

    The issue of whether ERK activation determines matrix synthesis or degradation in osteoarthritis (OA) pathogenesis currently remains controversial. Our previous study shows that PLCγ1 and mTOR are involved in the matrix metabolism of OA cartilage. Investigating the interplays of PLCγ1, mTOR and ERK in matrix degradation of OA will facilitate future attempts to manipulate ERK in OA prevention and therapy. Here, cultured human normal chondrocytes and OA chondrocytes were treated with different inhibitors or transfected with expression vectors, respectively. The levels of ERK, p-ERK, PLCγ1, p-PLCγ1, mTOR, p-mTOR and MMP-13 were then evaluated by Western blotting analysis. The results manifested that the expression level of ERK in human OA chondrocytes was lower than that in human normal articular chondrocytes, and the up-regulation of ERK could promote matrix synthesis, including the decrease in MMP-13 level and the increase in Aggrecan level in human OA chondrocytes. Furthermore, the PLCγ1/ERK axis and a mutual inhibition of mTOR and ERK were observed in human OA chondrocytes. Interestingly, activated ERK had no inhibitory effect on MMP-13 expression in PLCγ1-transformed OA chondrocytes. Combined with our previous study, the non-effective state of ERK activation by PLCγ1 on MMP-13 may be partly attributed to the inhibition of the PLCγ1/mTOR axis on the PLCγ1/ERK axis. Therefore, the study indicates that the mutual inhibition of ERK and mTOR is involved in PLCγ1-mediated MMP-13 expression in human OA chondrocytes, with important implication for the understanding of OA pathogenesis as well as for its prevention and therapy. PMID:26247939

  13. Synthesis of biocompatible nanoparticle drug complexes for inhibition of mycobacteria

    NASA Astrophysics Data System (ADS)

    Bhave, Tejashree; Ghoderao, Prachi; Sanghavi, Sonali; Babrekar, Harshada; Bhoraskar, S. V.; Ganesan, V.; Kulkarni, Anjali

    2013-12-01

    Tuberculosis (TB) is one of the most critical infectious diseases affecting the world today. Current TB treatment involves six months long daily administration of four oral doses of antibiotics. Due to severe side effects and the long treatment, a patient's adherence is low and this results in relapse of symptoms causing an alarming increase in the prevalence of multi-drug resistant (MDR) TB. Hence, it is imperative to develop a new drug delivery technology wherein these effects can be reduced. Rifampicin (RIF) is one of the widely used anti-tubercular drugs (ATD). The present study discusses the development of biocompatible nanoparticle-RIF complexes with superior inhibitory activity against both Mycobacterium smegmatis (M. smegmatis) and Mycobacterium tuberculosis (M. tuberculosis). Iron oxide nanoparticles (NPs) synthesized by gas phase condensation and NP-RIF complexes were tested against M. smegmatis SN2 strain as well as M. tuberculosis H37Rv laboratory strain. These complexes showed significantly better inhibition of M. smegmatis SN2 strain at a much lower effective concentration (27.5 μg ml-1) as compared to neat RIF (125 μg ml-1). Similarly M. tuberculosis H37Rv laboratory strain was susceptible to both nanoparticle-RIF complex and neat RIF at a minimum inhibitory concentration of 0.22 and 1 μg ml-1, respectively. Further studies are underway to determine the efficacy of NPs-RIF complexes in clinical isolates of M. tuberculosis as well as MDR isolates.

  14. Characterizing Septum Inhibition in Mycobacterium tuberculosis for Novel Drug Discovery

    SciTech Connect

    Respicio,L.; Nair, P.; Huang, Q.; Anil, B.; Tracz, S.; Truglio, J.; Kisker, C.; Raleigh, D.; Ojima, I.; et al

    2008-01-01

    A temperature sensitive mutation in the cell division protein FtsZ was used in combination with transcriptional analysis to identify biomarkers for inhibition of septum formation. Crystallography and modeling revealed that the glycine for aspartate substitution at amino acid 210 was located in helix 8 of the protein, adjacent to the T7 synergy loop. To verify the molecular behavior of FtsZD210G, the in vitro activity and structural stability were evaluated as a function of temperature. These analyses confirmed that the FtsZD210G mutant had reduced GTPase and polymerization activity compared to wild-type FtsZ, and CD spectroscopy demonstrated that both FtsZD210G and wild-type FtsZ had similar structure and stability. Significantly, the FtsZD210G merodiploid strain of M. tuberculosis had compromised growth at 37 C, substantiating the suitability of FtsZD210G as a molecular tool for global analysis in response to improper FtsZ polymerization and septum inhibition. Advanced model-based bioinformatics and transcriptional mapping were used to identify high-content multiple features that provide biomarkers for the development of a rational drug screening platform for discovering novel chemotherapeutics that target cell division.

  15. Discovery of BC-01, a novel mutual prodrug (hybrid drug) of ubenimex and fluorouracil as anticancer agent.

    PubMed

    Jiang, Yuqi; Li, Xiaoyang; Hou, Jinning; Huang, Yongxue; Jia, Yuping; Zou, Mingming; Zhang, Jian; Wang, Xuejian; Xu, Wenfang; Zhang, Yingjie

    2016-10-01

    We designed and synthesized a novel mutual prodrug, named BC-01 (3), by integrating ubenimex and Fluorouracil (5-FU) into one molecule based on prior research results that showed that a combination of the aminopeptidase N (CD13) inhibitor, ubenimex, and the cytotoxic antitumor agent, 5-FU, exhibited improved in vitro and in vivo antitumor efficiency. 3 showed potent inhibitory activity against CD13 enzymatic activity. Compared with ubenimex, 3 exhibited more potent anti-angiogenesis effects, and compared with the approved 5-FU prodrug, capecitabine, 3 exhibited more potent tumor growth inhibitory and anti-metastasis effects. Additionally, compared with 5-FU or 5-FU plus ubenimex, 3 also exhibited a superior antitumor efficiency even in our 5-FU-resistant mice model. Other antitumor agents could be conjugated with ubenimex using this strategy to obtain novel mutual prodrugs with promising antitumor potency. PMID:27322756

  16. DMSO inhibits human platelet activation through cyclooxygenase-1 inhibition. A novel agent for drug eluting stents?

    SciTech Connect

    Asmis, Lars; Tanner, Felix C.; Sudano, Isabella; Luescher, Thomas F.; Camici, Giovanni G.

    2010-01-22

    Background: DMSO is routinely infused together with hematopoietic cells in patients undergoing myeloablative therapy and was recently found to inhibit smooth muscle cells proliferation and arterial thrombus formation in the mouse by preventing tissue factor (TF), a key activator of the coagulation cascade. This study was designed to investigate whether DMSO prevents platelet activation and thus, whether it may represent an interesting agent to be used on drug eluting stents. Methods and results: Human venous blood from healthy volunteers was collected in citrated tubes and platelet activation was studied by cone and platelet analyzer (CPA) and rapid-platelet-function-assay (RPFA). CPA analysis showed that DMSO-treated platelets exhibit a lower adherence in response to shear stress (-15.54 {+-} 0.9427%, n = 5, P < 0.0001 versus control). Additionally, aggregometry studies revealed that DMSO-treated, arachidonate-stimulated platelets had an increased lag phase (18.0% {+-} 4.031, n = 9, P = 0.0004 versus control) as well as a decreased maximal aggregation (-6.388 {+-} 2.212%, n = 6, P = 0.0162 versus control). Inhibitory action of DMSO could be rescued by exogenous thromboxane A2 and was mediated, at least in part, by COX-1 inhibition. Conclusions: Clinically relevant concentrations of DMSO impair platelet activation by a thromboxane A2-dependent, COX-1-mediated effect. This finding may be crucial for the previously reported anti-thrombotic property displayed by DMSO. Our findings support a role for DMSO as a novel drug to prevent not only proliferation, but also thrombotic complications of drug eluting stents.

  17. Inhibition of Plasmodium falciparum dihydropteroate synthetase and growth in vitro by sulfa drugs.

    PubMed Central

    Zhang, Y; Meshnick, S R

    1991-01-01

    The Michaelis-Menten inhibitory constants (Kis) and the concentrations required for 50% inhibition of the Plasmodium falciparum dihydropteroate synthetase were determined for six sulfa drugs. These drugs inhibited the in vitro growth of P. falciparum (50% lethal concentration) at concentrations of 30 to 500 nM; these concentrations were 100 to 1,000 times lower than the concentrations required for 50% inhibition and Kis (6 to 500 microM). The uptake of p-aminobenzoic acid was not inhibited by the sulfa drugs. However, infected erythrocytes took up more labeled sulfamethoxazole than did uninfected erythrocytes. Thus, the concentration of sulfa drugs by malaria parasites may explain how sulfa drugs inhibit in vitro growth of parasites through the inhibition of dihydropteroate synthetase. PMID:2024960

  18. New Life for an Old Drug: the Anthelmintic Drug Niclosamide Inhibits Pseudomonas aeruginosa Quorum Sensing

    PubMed Central

    Imperi, Francesco; Massai, Francesco; Ramachandran Pillai, Cejoice; Longo, Francesca; Zennaro, Elisabetta; Rampioni, Giordano; Visca, Paolo

    2013-01-01

    The need for novel antibacterial strategies and the awareness of the importance of quorum sensing (QS) in bacterial infections have stimulated research aimed at identifying QS inhibitors (QSIs). However, clinical application of QSIs identified so far is still distant, likely due to their unsuitability for use in humans. A promising way to overcome this problem is searching for anti-QS side activity among the thousands of drugs approved for clinical use in the treatment of different diseases. Here, we applied this strategy to the search for QSIs, by screening a library of FDA-approved compounds for their ability to inhibit the QS response in the Gram-negative pathogen Pseudomonas aeruginosa. We found that the anthelmintic drug niclosamide strongly inhibits the P. aeruginosa QS response and production of acyl-homoserine lactone QS signal molecules. Microarray analysis showed that niclosamide affects the transcription of about 250 genes, with a high degree of target specificity toward the QS-dependent regulon. Phenotypic assays demonstrated that niclosamide suppresses surface motility and production of the secreted virulence factors elastase, pyocyanin, and rhamnolipids, and it reduces biofilm formation. In accordance with the strong antivirulence activity disclosed in vitro, niclosamide prevented P. aeruginosa pathogenicity in an insect model of acute infection. Besides the finding that an FDA-approved drug has a promising antivirulence activity against one of the most antibiotic-resistant bacterial pathogens, this work provides a proof of concept that a lateral anti-QS activity can be detected among drugs already used in humans, validating a new approach to identify QSIs that could easily move into clinical applications. PMID:23254430

  19. Smooth muscle-specific switching of alpha-tropomyosin mutually exclusive exon selection by specific inhibition of the strong default exon.

    PubMed

    Gooding, C; Roberts, G C; Moreau, G; Nadal-Ginard, B; Smith, C W

    1994-08-15

    Exons 2 and 3 of alpha-tropomyosin are spliced in a strict mutually exclusive manner. Exon 3 is a default choice, being selected in almost all cell types where the gene is expressed. The default selection arises from a competition between the two exons, in which the stronger branch point/pyrimidine tract elements of exon 3 win. Exon 2 is selected predominantly or exclusively only in smooth muscle cells. We show here that the basis for the smooth muscle-specific switching of exon selection is inhibition of exon 3. Exon 3 is still skipped with smooth muscle specificity, even in the absence of exon 2. We have defined two conserved sequence elements, one in each of the introns flanking exon 3, that are essential for this regulation. Mutation of either element severely impairs regulated suppression of exon 3. No other exon or intron sequences appear to be necessary for regulation. We have also demonstrated skipping of exon 3 that is dependent upon both regulatory elements in an in vitro splicing assay. We further show that both splice sites of exon 3 must be inhibited in a concerted fashion to switch to selection of exon 2. This may relate to the requirement for negative elements on both sides of the exon. PMID:8070413

  20. Importance of multi-P450 inhibition in drug-drug interactions: evaluation of incidence, inhibition magnitude and prediction from in vitro data

    PubMed Central

    Isoherranen, Nina; Lutz, Justin D; Chung, Sophie P; Hachad, Houda; Levy, Rene H; Ragueneau-Majlessi, Isabelle

    2012-01-01

    Drugs that are mainly cleared by a single enzyme are considered more sensitive to drug-drug interactions (DDIs) than drugs cleared by multiple pathways. However, whether this is true when a drug cleared by multiple pathways is co-administered with an inhibitor of multiple P450 enzymes (multi-P450 inhibition) is not known. Mathematically, simultaneous equipotent inhibition of two elimination pathways that each contributes half of the drug clearance is equal to equipotent inhibition of a single pathway that clears the drug. However, simultaneous strong or moderate inhibition of two pathways by a single inhibitor is perceived as an unlikely scenario. The aim of this study was (i) to identify P450 inhibitors currently in clinical use that can inhibit more than one clearance pathway of an object drug in vivo, and (ii) to evaluate the magnitude and predictability of DDIs caused by these multi-P450 inhibitors. Multi-P450 inhibitors were identified using the Metabolism and Transport Drug Interaction Database™. A total of 38 multi-P450 inhibitors, defined as inhibitors that increased the AUC or decreased the clearance of probes of two or more P450’s, were identified. Seventeen (45 %) multi-P450 inhibitors were strong inhibitors of at least one P450 and an additional 12 (32 %) were moderate inhibitors of one or more P450s. Only one inhibitor (fluvoxamine) was a strong inhibitor of more than one enzyme. Fifteen of the multi-P450 inhibitors also inhibit drug transporters in vivo, but such data are lacking on many of the inhibitors. Inhibition of multiple P450 enzymes by a single inhibitor resulted in significant (>2-fold) clinical DDIs with drugs that are cleared by multiple pathways such as imipramine and diazepam while strong P450 inhibitors resulted in only weak DDIs with these object drugs. The magnitude of the DDIs between multi-P450 inhibitors and diazepam, imipramine and omeprazole could be predicted using in vitro data with similar accuracy as probe substrate

  1. Reversible and irreversible inhibition of thyroid peroxidase-catalyzed iodination by thioureylene drugs.

    PubMed

    Engler, H; Taurog, A; Luthy, C; Dorris, M L

    1983-01-01

    The mechanism of reversible and irreversible inhibition of thyroid peroxidase (TPO)-catalyzed iodination by thioureylene drugs was investigated using a model incubation system. The major observations may be summarized as follows. 1) TPO is inactivated by 1-methyl-2-mercaptoimidazole and propylthiouracil even in the presence of a relatively high concentration of iodide. The extent of this inactivation depends on the ratio of iodide to drug. 2) Spectral changes observed on oxidation of the drugs with the peroxidase-iodide system were very similar to those observed when the drugs were oxidized nonenzymatically with I3-. These findings support the view that oxidized iodine is an intermediate in TPO-catalyzed oxidation of the drugs. 3) Under conditions where TPO is largely inactivated, inhibition of iodination is complete and irreversible. Drug metabolism, on the other hand, occurs to a limited extent. 4) Under conditions where TPO is only partially inactivated, inhibition of iodination is transient (reversible). In this case, drug metabolism is extensive, and higher oxidation products (sulfate and sulfinic acid) are observed. Inhibition of iodination occurs only during the interval required to reduce the drug concentration to a low level. Thereafter, iodination may occur at a rate close to that observed in the absence of drug. Based on these and other observations, a scheme is presented to explain the mechanism of reversible and irreversible inhibition of iodination. In essence, the type of inhibition depends on the relative rates and extent of TPO inactivation and drug oxidation. These rates, in turn, depend primarily on the iodide to drug concentration ratio. A high ratio favors extensive drug oxidation and reversible inhibition. A low ratio favors TPO inactivation and irreversible inhibition. PMID:6847836

  2. A Key Commitment Step in Erythropoiesis Is Synchronized with the Cell Cycle Clock through Mutual Inhibition between PU.1 and S-Phase Progression

    PubMed Central

    Pop, Ramona; Shearstone, Jeffrey R.; Shen, Qichang; Liu, Ying; Hallstrom, Kelly; Koulnis, Miroslav; Gribnau, Joost; Socolovsky, Merav

    2010-01-01

    Hematopoietic progenitors undergo differentiation while navigating several cell division cycles, but it is unknown whether these two processes are coupled. We addressed this question by studying erythropoiesis in mouse fetal liver in vivo. We found that the initial upregulation of cell surface CD71 identifies developmentally matched erythroblasts that are tightly synchronized in S-phase. We show that DNA replication within this but not subsequent cycles is required for a differentiation switch comprising rapid and simultaneous committal transitions whose precise timing was previously unknown. These include the onset of erythropoietin dependence, activation of the erythroid master transcriptional regulator GATA-1, and a switch to an active chromatin conformation at the β-globin locus. Specifically, S-phase progression is required for the formation of DNase I hypersensitive sites and for DNA demethylation at this locus. Mechanistically, we show that S-phase progression during this key committal step is dependent on downregulation of the cyclin-dependent kinase p57KIP2 and in turn causes the downregulation of PU.1, an antagonist of GATA-1 function. These findings therefore highlight a novel role for a cyclin-dependent kinase inhibitor in differentiation, distinct to their known function in cell cycle exit. Furthermore, we show that a novel, mutual inhibition between PU.1 expression and S-phase progression provides a “synchromesh” mechanism that “locks” the erythroid differentiation program to the cell cycle clock, ensuring precise coordination of critical differentiation events. PMID:20877475

  3. Drug-induced Inhibition and Trafficking Disruption of ion Channels: Pathogenesis of QT Abnormalities and Drug-induced Fatal Arrhythmias.

    PubMed

    Cubeddu, Luigi X

    2016-01-01

    Risk of severe and fatal ventricular arrhythmias, presenting as Torsade de Pointes (TdP), is increased in congenital and acquired forms of long QT syndromes (LQTS). Drug-induced inhibition of K+ currents, IKs, IKr, IK1, and/or Ito, delay repolarization, prolong QT, and increase the risk of TdP. Drug-induced interference with IKr is the most common cause of acquired LQTS/TdP. Multiple drugs bind to KNCH2-hERG-K+ channels affecting IKr, including antiarrythmics, antibiotics, antivirals, azole-antifungals, antimalarials, anticancer, antiemetics, prokinetics, antipsychotics, and antidepressants. Azithromycin has been recently added to this list. In addition to direct channel inhibition, some drugs interfere with the traffic of channels from the endoplasmic reticulum to the cell membrane, decreasing mature channel membrane density; e.g., pentamidine, geldalamicin, arsenic trioxide, digoxin, and probucol. Other drugs, such as ketoconazole, fluoxetine, norfluoxetine, citalopram, escitalopram, donepezil, tamoxifen, endoxifen, atazanavir, and roxitromycin, induce both direct channel inhibition and impaired channel trafficking. Although many drugs prolong the QT interval, TdP is a rare event. The following conditions increase the risk of drug-induced TdP: a) Disease states/electrolyte levels (heart failure, structural cardiac disease, bradycardia, hypokalemia); b) Pharmacogenomic variables (presence of congenital LQTS, subclinical ion-channel mutations, history of or having a relative with history of drug-induced long QT/TdP); c) Pharmacodynamic and kinetic factors (high doses, women, elderly, metabolism inhibitors, combining two or more QT prolonging drugs, drugs that prolong the QT and increase QT dispersion, and drugs with multiple actions on ion channels). Because most of these conditions are preventable, careful evaluation of risk factors and increased knowledge of drug use associated with repolarization abnormalities are strongly recommended. PMID:26926294

  4. Conjugation to polymeric chains of influenza drugs targeting M2 ion channels partially restores inhibition of drug-resistant mutants

    PubMed Central

    Larson, Alyssa M.; Chen, Jianzhu; Klibanov, Alexander M.

    2013-01-01

    By attaching multiple copies of the influenza M2 ion channel inhibitors amantadine (1) and rimantadine (2) to polymeric chains we endeavored to recover their potency in inhibiting drug-resistant influenza viruses. Depending on loading densities, as well as the nature of the drug, the polymer, and the spacer arm, polymer-conjugated drugs were up to 30-fold more potent inhibitors of drug-resistant strains than their monomeric parents. In particular, a 20% loading density and a short linker group on the negatively charged poly-L-glutamate resulted in some of the most potent inhibitors for 2′s conjugates against drug-resistant influenza strains. Although full recovery of the inhibitory action against drug-resistant strains was not achieved, this study may be a step toward salvaging anti-influenza drugs that are no longer effective. PMID:23832466

  5. Conjugation to polymeric chains of influenza drugs targeting M2 ion channels partially restores inhibition of drug-resistant mutants.

    PubMed

    Larson, Alyssa M; Chen, Jianzhu; Klibanov, Alexander M

    2013-08-01

    By attaching multiple copies of the influenza M2 ion channel inhibitors amantadine (1) and rimantadine (2) to polymeric chains, we endeavored to recover their potency in inhibiting drug-resistant influenza viruses. Depending on loading densities, as well as the nature of the drug, the polymer, and the spacer arm, polymer-conjugated drugs were up to 30-fold more potent inhibitors of drug-resistant strains than their monomeric parents. In particular, a 20% loading density and a short linker group on the negatively charged poly-l-glutamate resulted in one of the most potent inhibitors for 2's conjugates against drug-resistant influenza strains. Although full recovery of the inhibitory action against drug-resistant strains was not achieved, this study may be a step toward salvaging anti-influenza drugs that are no longer effective. PMID:23832466

  6. Assessment of cytochrome p450 enzyme inhibition and inactivation in drug discovery and development.

    PubMed

    Nettleton, David O; Einolf, Heidi J

    2011-01-01

    Evaluation of the potential of a drug candidate to inhibit or inactivate cytochrome P450 (CYP) enzymes remains an important part of pharmaceutical drug Discovery and Development programs. CYP enzymes are considered to be one of the most important enzyme families involved in the metabolic clearance of the vast majority of prescribed drugs. Clinical drug-drug interactions (DDI) involving inhibition or time-dependent inactivation of these enzymes can result in dangerous side effects resulting from reduced clearance/increased exposure of the drug being affected (the 'victim' drug). In this regard, pharmaceutical companies have become quite vigilant in mitigating CYP inhibition/inactivation liabilities of drug candidates early in Discovery including continued risk assessment throughout Development. In this review, common strategies and decision making processes for the assessment of DDI risk in the different stages of pharmaceutical development are discussed. In addition, in vitro study designs, analysis, and interpretation of CYP inhibition and inactivation data are described in stage appropriate context. The in vitro tools and knowledge available now enable the Discovery Chemist to place the potential CYP DDI liability of a drug candidate into perspective and to aid in the optimization of chemical drug design to further mitigate this risk. PMID:21320066

  7. Use of Human Plasma Samples to Identify Circulating Drug Metabolites that Inhibit Cytochrome P450 Enzymes.

    PubMed

    Eng, Heather; Obach, R Scott

    2016-08-01

    Drug interactions elicited through inhibition of cytochrome P450 (P450) enzymes are important in pharmacotherapy. Recently, greater attention has been focused on not only parent drugs inhibiting P450 enzymes but also on possible inhibition of these enzymes by circulating metabolites. In this report, an ex vivo method whereby the potential for circulating metabolites to be inhibitors of P450 enzymes is described. To test this method, seven drugs and their known plasma metabolites were added to control human plasma at concentrations previously reported to occur in humans after administration of the parent drug. A volume of plasma for each drug based on the known inhibitory potency and time-averaged concentration of the parent drug was extracted and fractionated by high-pressure liquid chromatography-mass spectrometry, and the fractions were tested for inhibition of six human P450 enzyme activities (CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4). Observation of inhibition in fractions that correspond to the retention times of metabolites indicates that the metabolite has the potential to contribute to P450 inhibition in vivo. Using this approach, norfluoxetine, hydroxyitraconazole, desmethyldiltiazem, desacetyldiltiazem, desethylamiodarone, hydroxybupropion, erythro-dihydrobupropion, and threo-dihydrobupropion were identified as circulating metabolites that inhibit P450 activities at a similar or greater extent as the parent drug. A decision tree is presented outlining how this method can be used to determine when a deeper investigation of the P450 inhibition properties of a drug metabolite is warranted. PMID:27271369

  8. Inhibition of P-glycoprotein by psychotherapeutic drugs in a canine cell model.

    PubMed

    Schrickx, J A; Fink-Gremmels, J

    2014-10-01

    Drug-drug interactions related to long-term therapies are of increasing concern. Psychotherapeutic drugs, licensed for the use in dogs for the management of separation anxiety and other behavioural disorders, are examples of drugs used in long-term therapies. In an in vitro system with canine P-glycoprotein (P-gp) expressing cell lines, three psychotherapeutic drugs with a different mode of action were tested for their ability to inhibit the canine multidrug transporter P-gp. At 10 μm, the selective serotonin reuptake inhibitor fluoxetine and the tricyclic antidepressant clomipramine inhibited P-gp for 41% and 59%, respectively. In contrast, selegeline did not inhibit the function of the canine P-gp. PMID:24602126

  9. Organ Impairment—Drug–Drug Interaction Database: A Tool for Evaluating the Impact of Renal or Hepatic Impairment and Pharmacologic Inhibition on the Systemic Exposure of Drugs

    PubMed Central

    Yeung, CK; Yoshida, K; Kusama, M; Zhang, H; Ragueneau-Majlessi, I; Argon, S; Li, L; Chang, P; Le, CD; Zhao, P; Zhang, L; Sugiyama, Y; Huang, S-M

    2015-01-01

    The organ impairment and drug–drug interaction (OI-DDI) database is the first rigorously assembled database of pharmacokinetic drug exposure data from publicly available renal and hepatic impairment studies presented together with the maximum change in drug exposure from drug interaction inhibition studies. The database was used to conduct a systematic comparison of the effect of renal/hepatic impairment and pharmacologic inhibition on drug exposure. Additional applications are feasible with the public availability of this database. PMID:26380158

  10. Stage-dependent inhibition of HIV-1 replication by antiretroviral drugs in cell culture.

    PubMed

    Donahue, Daniel A; Sloan, Richard D; Kuhl, Björn D; Bar-Magen, Tamara; Schader, Susan M; Wainberg, Mark A

    2010-03-01

    Recent clinical trials have shown that the use of the HIV-1 integrase (IN) inhibitor raltegravir (RAL) results in drops in the viral load that are more rapid than those achieved by use of the reverse transcriptase (RT) inhibitor efavirenz. Previously, mathematical modeling of viral load decay that takes into account the stage of viral replication targeted by a drug has yielded data that closely approximate the clinical trial results. This model predicts greater inhibition of viral replication by drugs that act later in the viral replication cycle. In the present study, we have added drugs that target entry, reverse transcription, integration, or proteolytic processing to acutely infected cells and have shown modest viral inhibition by entry inhibitors, intermediate levels of inhibition by RT and IN inhibitors, and high levels of inhibition by protease inhibitors relative to the levels of growth for the no-drug controls. When dual or triple combinations of these drugs were added to acutely infected cells, we found that the levels of inhibition achieved by any given combination were comparable to those achieved by the latest-acting drug in the combination. In single-round infections in which the kinetics of reverse transcription and integration had been determined by quantitative PCR, addition of IN inhibitors at various times postinfection resulted in levels of inhibition equal to or greater than those achieved by addition of RT inhibitors. Collectively, our data provide in vitro evidence of the stage-dependent inhibition of HIV-1 by clinically relevant drugs. We discuss how stage-dependent inhibition helps to explain the unique viral load decay dynamics observed clinically with RAL. PMID:20038621

  11. Photodegradation and inhibition of drug-resistant influenza virus neuraminidase using anthraquinone-sialic acid hybrids.

    PubMed

    Aoki, Yusuke; Tanimoto, Shuho; Takahashi, Daisuke; Toshima, Kazunobu

    2013-02-11

    The anthraquinone-sialic acid hybrids designed effectively degraded not only non-drug-resistant neuraminidase but also drug-resistant neuraminidase, which is an important target of anti-influenza therapy. Degradation was achieved using long-wavelength UV radiation in the absence of any additives and under neutral conditions. Moreover, the hybrids efficiently inhibited neuraminidase activities upon photo-irradiation. PMID:23282898

  12. Drug inhibition profile prediction for NFκB pathway in multiple myeloma.

    PubMed

    Peng, Huiming; Wen, Jianguo; Li, Hongwei; Chang, Jeff; Zhou, Xiaobo

    2011-01-01

    Nuclear factor κB (NFκB) activation plays a crucial role in anti-apoptotic responses in response to the apoptotic signaling during tumor necrosis factor (TNFα) stimulation in Multiple Myeloma (MM). Although several drugs have been found effective for the treatment of MM by mainly inhibiting NFκB pathway, there are not any quantitative or qualitative results of comparison assessment on inhibition effect between different drugs either used alone or in combinations. Computational modeling is becoming increasingly indispensable for applied biological research mainly because it can provide strong quantitative predicting power. In this study, a novel computational pathway modeling approach is employed to comparably assess the inhibition effects of specific drugs used alone or in combinations on the NFκB pathway in MM and to predict the potential synergistic drug combinations. PMID:21408099

  13. Inhibition of Pneumocystis carinii dihydropteroate synthetase by sulfa drugs.

    PubMed Central

    Merali, S; Zhang, Y; Sloan, D; Meshnick, S

    1990-01-01

    A new reversed-phase high-pressure liquid chromatography assay procedure for dihydropteroate synthetase (DHPS) that involves the elution of the enzyme incubation solution with a series of three solvents of decreasing polarity (ammonium phosphate buffer, 10% methanol, and 50% methanol) was designed. By this procedure DHPS was detected in Escherichia coli and Pneumocystis carinii with specific activities of 450 and 14 U/mg, respectively. A comparison of the effects of five sulfa drugs on P. carinii DHPS activity revealed that dapsone is the most potent of these drugs. PMID:2203302

  14. Cognitive control of drug craving inhibits brain reward regions in cocaine abusers

    SciTech Connect

    Volkow, N.D.; Fowler, J.; Wang, G.J.; Telang, F.; Logan, J.; Jayne, M.; Ma, Y.; Pradhan, K.; Wong, C.T.; Swanson, J.M.

    2010-01-01

    Loss of control over drug taking is considered a hallmark of addiction and is critical in relapse. Dysfunction of frontal brain regions involved with inhibitory control may underlie this behavior. We evaluated whether addicted subjects when instructed to purposefully control their craving responses to drug-conditioned stimuli can inhibit limbic brain regions implicated in drug craving. We used PET and 2-deoxy-2[18F]fluoro-D-glucose to measure brain glucose metabolism (marker of brain function) in 24 cocaine abusers who watched a cocaine-cue video and compared brain activation with and without instructions to cognitively inhibit craving. A third scan was obtained at baseline (without video). Statistical parametric mapping was used for analysis and corroborated with regions of interest. The cocaine-cue video increased craving during the no-inhibition condition (pre 3 {+-} 3, post 6 {+-} 3; p < 0.001) but not when subjects were instructed to inhibit craving (pre 3 {+-} 2, post 3 {+-} 3). Comparisons with baseline showed visual activation for both cocaine-cue conditions and limbic inhibition (accumbens, orbitofrontal, insula, cingulate) when subjects purposefully inhibited craving (p < 0.001). Comparison between cocaine-cue conditions showed lower metabolism with cognitive inhibition in right orbitofrontal cortex and right accumbens (p < 0.005), which was associated with right inferior frontal activation (r = -0.62, p < 0.005). Decreases in metabolism in brain regions that process the predictive (nucleus accumbens) and motivational value (orbitofrontal cortex) of drug-conditioned stimuli were elicited by instruction to inhibit cue-induced craving. This suggests that cocaine abusers may retain some ability to inhibit craving and that strengthening fronto-accumbal regulation may be therapeutically beneficial in addiction.

  15. Tyrosine Kinase Inhibition: An Approach to Drug Development

    NASA Astrophysics Data System (ADS)

    Levitzki, Alexander; Gazit, Aviv

    1995-03-01

    Protein tyrosine kinases (PTKs) regulate cell proliferation, cell differentiation, and signaling processes in the cells of the immune system. Uncontrolled signaling from receptor tyrosine kinases and intracellular tyrosine kinases can lead to inflammatory responses and to diseases such as cancer, atherosclerosis, and psoriasis. Thus, inhibitors that block the activity of tyrosine kinases and the signaling pathways they activate may provide a useful basis for drug development. This article summarizes recent progress in the development of PTK inhibitors and demonstrates their potential use in the treatment of disease.

  16. Microencapsulated drug delivery: a new approach to pro-inflammatory cytokine inhibition

    PubMed Central

    Oettinger, Carl W.; D'Souza, Martin J.

    2012-01-01

    Context: This article reviews the use of albumin microcapsules 3–4 mm in size containing cytokine inhibiting drugs which include neutralizing antibodies to TNF and IL1, CNI-1493, antisense oligonucleotides to TNF and NF-kappaB, and the antioxidant catalase. Objective: Describe the effects, cellular uptake and distribution of microencapsulated drugs and the effect in both a peritonitis model of infection and a model of adjuvant-induced arthritis. Methods: The studies performed by our group are reviewed, the only such studies available. Results: Microencapsulation of these compounds produced high intracellular drug concentrations due to rapid uptake by phagocytic cells, including endothelial cells, without toxicity. All compounds produced excellent inhibition of TNF and IL1 resulting in improved animal survival in a peritonitis model of septic shock and inflammation in an arthritis model. Conclusion: Albumin microencapsulated pro-inflammatory cytokine inhibiting compounds are superior to equivalent concentration of these compounds administered in solution form. PMID:22348221

  17. Modeling synergistic drug inhibition of Mycobacterium tuberculosis growth in murine macrophages.

    PubMed

    Fang, Xin; Wallqvist, Anders; Reifman, Jaques

    2011-09-01

    We developed a metabolism-based systems biology framework to model drug-induced growth inhibition of Mycobacterium tuberculosis in murine macrophage cells. We used it to simulate ex vivo bacterial growth inhibition due to 3-nitropropionate (3-NP) and calculated the corresponding time- and drug concentration-dependent dose-response curves. 3-NP targets the isocitrate lyase 1 (ICL1) and ICL2 enzymes in the glyoxylate shunt, an essential component in carbon metabolism of many important prokaryotic organisms. We used the framework to in silico mimic drugging additional enzymes in combination with 3-NP to understand how synergy can arise among metabolic enzyme targets. In particular, we focused on exploring additional targets among the central carbon metabolism pathways and ascertaining the impact of jointly inhibiting these targets and the ICL1/ICL2 enzymes. Thus, additionally inhibiting the malate synthase (MS) enzyme in the glyoxylate shunt did not produce synergistic effects, whereas additional inhibition of the glycerol-3-phosphate dehydrogenase (G3PD) enzyme showed a reduction in bacterial growth beyond what each single inhibition could achieve. Whereas the ICL1/ICL2-MS pair essentially works on the same branch of the metabolic pathway processing lipids as carbon sources (the glyoxylate shunt), the ICL1/ICL2-G3PD pair inhibition targets different branches among the lipid utilization pathways. This allowed the ICL1/ICL2-G3PD drug combination to synergistically inhibit carbon processing and ultimately affect cellular growth. Our previously developed model for in vitro conditions failed to capture these effects, highlighting the importance of constructing accurate representations of the experimental ex vivo macrophage system. PMID:21713281

  18. Inhibitions of several antineoplastic drugs on serum sialic Acid levels in mice bearing tumors.

    PubMed

    Lu, Da-Yong; Xu, Jing; Lu, Ting-Ren; Wu, Hong-Ying; Xu, Bin

    2013-03-01

    Six murine tumors, including ascetic tumors HepA, EC, P388 leukemia, S180 and solid tumor S180, and Lewis lung carcinoma, were employed in this work. The free sialic acid concentrations in both blood and ascites were measured in tumor-bearing mice. The results showed that the content of sialic acids in blood was increased in tumor growth and certain tumor types. Higher sialic acid content was observed in ascites than that present in blood. The influence of antineoplastic agents (vincristine, thiotepa, adriamycin, probimane, cisplatin, oxalysine, cortisone, nitrogen mustard, lycobetaine, Ara-C, harringtonine, and cyclophosphamide) on the content of sialic acids in mice blood bearing solid tumors of either S180 or Lewis lung carcinoma was observed. Different inhibitions of antineoplastic drugs on both tumor growth and serum sialic acid levels in mice bearing tumors were found. Among these antineoplastic drugs, probimane, cisplatin, nitrogen mustard, and lycobetaine were able to decrease the serum sialic acid levels in mice bearing tumors. Since these four antineoplastic drugs are all DNA chelating agents, it was proposed that the inhibition of tumor sialic acids by these drugs might be through the DNA template via two ways. Since we have found no effect of antineoplastic drugs on serum sialic acid levels in normal mice, this suggests that the inhibition of antineoplastic drugs on sialic acids is by tumor involvement. PMID:23641340

  19. Inhibition of mast cell-dependent conversion of cultured macrophages into foam cells with antiallergic drugs.

    PubMed

    Ma, H; Kovanen, P T

    2000-12-01

    Degranulation of isolated, rat peritoneal mast cells in the presence of low density lipoprotein (LDL) induces cholesteryl ester accumulation in cocultured macrophages with ensuing foam cell formation. This event occurs when the macrophages phagocytose LDL particles that have been bound to the heparin proteoglycans of exocytosed granules. In an attempt to inhibit such foam cell formation pharmacologically, rat peritoneal mast cells that had been passively sensitized with anti-ovalbumin-IgE were treated with 2 mast cell-stabilizing antianaphylactic drugs, MY-1250 or disodium cromoglycate (DSCG). Both drugs were found to inhibit antigen (ovalbumin)-triggered release of histamine from the mast cells, revealing mast cell stabilization. In cocultures of rat peritoneal macrophages and passively sensitized mast cells, addition of MY-1250 before addition of the antigen resulted in parallel reductions in histamine release from mast cells, uptake of [(14)C]sucrose-LDL, and accumulation of LDL-derived cholesteryl esters in the cocultured macrophages. Similarly, when passively sensitized mast cells were stimulated with antigen in the presence of DSCG and the preconditioned media containing all substances released from the drug-treated mast cells were collected and added to macrophages cultured in LDL-containing medium, uptake and esterification of LDL cholesterol by the macrophages were inhibited. The inhibitory effects of both drugs were mast cell-specific because neither drug inhibited the ability of macrophages to take up and esterify LDL cholesterol. Analysis of heparin proteoglycan contents of the incubation media revealed that both drugs had inhibited mast cells from expelling their granule remnants. Thus, both MY-1250 and DSCG prevent mast cells from releasing the heparin proteoglycan-containing vehicles that bind LDL and carry it into macrophages. This study suggests that antiallergic pharmacological agents could be used in animal models to prevent mast cell

  20. Use-dependent inhibition of synaptic transmission by the secretion of intravesicularly accumulated antipsychotic drugs.

    PubMed

    Tischbirek, Carsten H; Wenzel, Eva M; Zheng, Fang; Huth, Tobias; Amato, Davide; Trapp, Stefan; Denker, Annette; Welzel, Oliver; Lueke, Katharina; Svetlitchny, Alexei; Rauh, Manfred; Deusser, Janina; Schwab, Annemarie; Rizzoli, Silvio O; Henkel, Andreas W; Müller, Christian P; Alzheimer, Christian; Kornhuber, Johannes; Groemer, Teja W

    2012-06-01

    Antipsychotic drugs are effective for the treatment of schizophrenia. However, the functional consequences and subcellular sites of their accumulation in nervous tissue have remained elusive. Here, we investigated the role of the weak-base antipsychotics haloperidol, chlorpromazine, clozapine, and risperidone in synaptic vesicle recycling. Using multiple live-cell microscopic approaches and electron microscopy of rat hippocampal neurons as well as in vivo microdialysis experiments in chronically treated rats, we demonstrate the accumulation of the antipsychotic drugs in synaptic vesicles and their release upon neuronal activity, leading to a significant increase in extracellular drug concentrations. The secreted drugs exerted an autoinhibitory effect on vesicular exocytosis, which was promoted by the inhibition of voltage-gated sodium channels and depended on the stimulation intensity. Taken together, these results indicate that accumulated antipsychotic drugs recycle with synaptic vesicles and have a use-dependent, autoinhibitory effect on synaptic transmission. PMID:22681688

  1. The Interactions of P-Glycoprotein with Antimalarial Drugs, Including Substrate Affinity, Inhibition and Regulation.

    PubMed

    Senarathna, S M D K Ganga; Page-Sharp, Madhu; Crowe, Andrew

    2016-01-01

    The combination of passive drug permeability, affinity for uptake and efflux transporters as well as gastrointestinal metabolism defines net drug absorption. Efflux mechanisms are often overlooked when examining the absorption phase of drug bioavailability. Knowing the affinity of antimalarials for efflux transporters such as P-glycoprotein (P-gp) may assist in the determination of drug absorption and pharmacokinetic drug interactions during oral absorption in drug combination therapies. Concurrent administration of P-gp inhibitors and P-gp substrate drugs may also result in alterations in the bioavailability of some antimalarials. In-vitro Caco-2 cell monolayers were used here as a model for potential drug absorption related problems and P-gp mediated transport of drugs. Artemisone had the highest permeability at around 50 x 10(-6) cm/sec, followed by amodiaquine around 20 x 10(-6) cm/sec; both mefloquine and artesunate were around 10 x 10(-6) cm/sec. Methylene blue was between 2 and 6 x 10(-6) cm/sec depending on the direction of transport. This 3 fold difference was able to be halved by use of P-gp inhibition. MRP inhibition also assisted the consolidation of the methylene blue transport. Mefloquine was shown to be a P-gp inhibitor affecting our P-gp substrate, Rhodamine 123, although none of the other drugs impacted upon rhodamine123 transport rates. In conclusion, mefloquine is a P-gp inhibitor and methylene blue is a partial substrate; methylene blue may have increased absorption if co-administered with such P-gp inhibitors. An upregulation of P-gp was observed when artemisone and dihydroartemisinin were co-incubated with mefloquine and amodiaquine. PMID:27045516

  2. The Interactions of P-Glycoprotein with Antimalarial Drugs, Including Substrate Affinity, Inhibition and Regulation

    PubMed Central

    Senarathna, S M D K Ganga; Page-Sharp, Madhu; Crowe, Andrew

    2016-01-01

    The combination of passive drug permeability, affinity for uptake and efflux transporters as well as gastrointestinal metabolism defines net drug absorption. Efflux mechanisms are often overlooked when examining the absorption phase of drug bioavailability. Knowing the affinity of antimalarials for efflux transporters such as P-glycoprotein (P-gp) may assist in the determination of drug absorption and pharmacokinetic drug interactions during oral absorption in drug combination therapies. Concurrent administration of P-gp inhibitors and P-gp substrate drugs may also result in alterations in the bioavailability of some antimalarials. In-vitro Caco-2 cell monolayers were used here as a model for potential drug absorption related problems and P-gp mediated transport of drugs. Artemisone had the highest permeability at around 50 x 10−6 cm/sec, followed by amodiaquine around 20 x 10−6 cm/sec; both mefloquine and artesunate were around 10 x 10−6 cm/sec. Methylene blue was between 2 and 6 x 10−6 cm/sec depending on the direction of transport. This 3 fold difference was able to be halved by use of P-gp inhibition. MRP inhibition also assisted the consolidation of the methylene blue transport. Mefloquine was shown to be a P-gp inhibitor affecting our P-gp substrate, Rhodamine 123, although none of the other drugs impacted upon rhodamine123 transport rates. In conclusion, mefloquine is a P-gp inhibitor and methylene blue is a partial substrate; methylene blue may have increased absorption if co-administered with such P-gp inhibitors. An upregulation of P-gp was observed when artemisone and dihydroartemisinin were co-incubated with mefloquine and amodiaquine. PMID:27045516

  3. Role of Molecular Interactions for Synergistic Precipitation Inhibition of Poorly Soluble Drug in Supersaturated Drug-Polymer-Polymer Ternary Solution.

    PubMed

    Prasad, Dev; Chauhan, Harsh; Atef, Eman

    2016-03-01

    We are reporting a synergistic effect of combined Eudragit E100 and PVP K90 in precipitation inhibition of indomethacin (IND) in solutions at low polymer concentration, a phenomenon that has significant implications on the usefulness of developing novel ternary solid dispersion of poorly soluble drugs. The IND supersaturation was created by cosolvent technique, and the precipitation studies were performed in the absence and the presence of individual and combined PVP K90 and Eudragit E100. The studies were also done with PEG 8000 as a noninteracting control polymer. A continuous UV recording of the IND absorption was used to observe changes in the drug concentration over time. The polymorphic form and morphology of precipitated IND were characterized by Raman spectroscopy and scanning electron microscopy. The change in the chemical shift in solution (1)H NMR was used as novel approach to probe IND-polymer interactions. Molecular modeling was used for calculating binding energy between IND-polymer as another indication of IND-polymer interaction. Spontaneous IND precipitation was observed in the absence of polymers. Eudragit E100 showed significant inhibitory effect on nuclei formation due to stronger interaction as reflected in higher binding energy and greater change in chemical shift by NMR. PVP K90 led to significant crystal growth inhibition due to adsorption on growing IND crystals as confirmed by modified crystal habit of precipitate in the presence of PVP K90. Combination of polymers resulted in a synergistic precipitation inhibition and extended supersaturation. The NMR confirmed interaction between IND-Eudragit E100 and IND-PVP K90 in solution. The combination of polymers showed similar peak shift albeit using lower polymer concentration indicating stronger interactions. The results established the significant synergistic precipitation inhibition effect upon combining Eudragit E100 and PVP K90 due to drug-polymer interaction. PMID:26866895

  4. Computational models for drug inhibition of the human apical sodium-dependent bile acid transporter.

    PubMed

    Zheng, Xiaowan; Ekins, Sean; Raufman, Jean-Pierre; Polli, James E

    2009-01-01

    The human apical sodium-dependent bile acid transporter (ASBT; SLC10A2) is the primary mechanism for intestinal bile acid reabsorption. In the colon, secondary bile acids increase the risk of cancer. Therefore, drugs that inhibit ASBT have the potential to increase the risk of colon cancer. The objectives of this study were to identify FDA-approved drugs that inhibit ASBT and to derive computational models for ASBT inhibition. Inhibition was evaluated using ASBT-MDCK monolayers and taurocholate as the model substrate. Computational modeling employed a HipHop qualitative approach, a Hypogen quantitative approach, and a modified Laplacian Bayesian modeling method using 2D descriptors. Initially, 30 compounds were screened for ASBT inhibition. A qualitative pharmacophore was developed using the most potent 11 compounds and applied to search a drug database, yielding 58 hits. Additional compounds were tested, and their K(i) values were measured. A 3D-QSAR and a Bayesian model were developed using 38 molecules. The quantitative pharmacophore consisted of one hydrogen bond acceptor, three hydrophobic features, and five excluded volumes. Each model was further validated with two external test sets of 30 and 19 molecules. Validation analysis showed both models exhibited good predictability in determining whether a drug is a potent or nonpotent ASBT inhibitor. The Bayesian model correctly ranked the most active compounds. In summary, using a combined in vitro and computational approach, we found that many FDA-approved drugs from diverse classes, such as the dihydropyridine calcium channel blockers and HMG CoA-reductase inhibitors, are ASBT inhibitors. PMID:19673539

  5. Computational Models for Drug Inhibition of the Human Apical Sodium-dependent Bile Acid Transporter

    PubMed Central

    Zheng, Xiaowan; Ekins, Sean; Raufman, Jean-Pierre; Polli, James E.

    2009-01-01

    The human apical sodium-dependent bile acid transporter (ASBT; SLC10A2) is the primary mechanism for intestinal bile acid re-absorption. In the colon, secondary bile acids increase the risk of cancer. Therefore, drugs that inhibit ASBT have the potential to increase the risk of colon cancer. The objectives of this study were to identify FDA-approved drugs that inhibit ASBT and to derive computational models for ASBT inhibition. Inhibition was evaluated using ASBT-MDCK monolayers and taurocholate as the model substrate. Computational modeling employed a HipHop qualitative approach, a Hypogen quantitative approach, as well as a modified Laplacian Bayesian modeling method using 2D descriptors. Initially, 30 compounds were screened for ASBT inhibition. A qualitative pharmacophore was developed using the most potent 11 compounds and applied to search a drug database, yielding 58 hits. Additional compounds were tested and their Ki values were measured. A 3D-QSAR and a Bayesian model were developed using 38 molecules. The quantitative pharmacophore consisted of one hydrogen bond acceptor, three hydrophobic features, and five excluded volumes. Each model was further validated with two external test sets of 30 and 19 molecules. Validation analysis showed both models exhibited good predictability in determining whether a drug is a potent or non-potent ASBT inhibitor. The Bayesian model correctly ranked the most active compounds. In summary, using a combined in vitro and computational approach, we found that many FDA-approved drugs from diverse classes, such as the dihydropyridine calcium channel blockers and HMG CoA-reductase inhibitors, are ASBT inhibitors. PMID:19673539

  6. Biomarker- versus drug-driven tumor growth inhibition models: an equivalence analysis.

    PubMed

    Sardu, Maria Luisa; Poggesi, Italo; De Nicolao, Giuseppe

    2015-12-01

    The mathematical modeling of tumor xenograft experiments following the dosing of antitumor drugs has received much attention in the last decade. Biomarker data can further provide useful insights on the pathological processes and be used for translational purposes in the early clinical development. Therefore, it is of particular interest the development of integrated pharmacokinetic-pharmacodynamic (PK-PD) models encompassing drug, biomarker and tumor-size data. This paper investigates the reciprocal consistency of three types of models: drug-to-tumor, such as established drug-driven tumor growth inhibition (TGI) models, drug-to-biomarker, e.g. indirect response models, and biomarker-to-tumor, e.g. the more recent biomarker-driven TGI models. In particular, this paper derives a mathematical relationship that guarantees the steady-state equivalence of the cascade of drug-to-biomarker and biomarker-to-tumor models with a drug-to-tumor TGI model. Using the Simeoni TGI model as a reference, conditions for steady-state equivalence are worked out and used to derive a new biomarker-driven model. Simulated and real data are used to show that in realistic cases the steady-state equivalence extends also to transient responses. The possibility of predicting the drug-to-tumor potency of a new candidate drug based only on biomarker response is discussed. PMID:26209955

  7. Sulfa Drugs Inhibit Sepiapterin Reduction and Chemical Redox Cycling by Sepiapterin Reductase

    PubMed Central

    Yang, Shaojun; Jan, Yi-Hua; Mishin, Vladimir; Richardson, Jason R.; Hossain, Muhammad M.; Heindel, Ned D.; Heck, Diane E.; Laskin, Debra L.

    2015-01-01

    Sepiapterin reductase (SPR) catalyzes the reduction of sepiapterin to dihydrobiopterin (BH2), the precursor for tetrahydrobiopterin (BH4), a cofactor critical for nitric oxide biosynthesis and alkylglycerol and aromatic amino acid metabolism. SPR also mediates chemical redox cycling, catalyzing one-electron reduction of redox-active chemicals, including quinones and bipyridinium herbicides (e.g., menadione, 9,10-phenanthrenequinone, and diquat); rapid reaction of the reduced radicals with molecular oxygen generates reactive oxygen species (ROS). Using recombinant human SPR, sulfonamide- and sulfonylurea-based sulfa drugs were found to be potent noncompetitive inhibitors of both sepiapterin reduction and redox cycling. The most potent inhibitors of sepiapterin reduction (IC50s = 31–180 nM) were sulfasalazine, sulfathiazole, sulfapyridine, sulfamethoxazole, and chlorpropamide. Higher concentrations of the sulfa drugs (IC50s = 0.37–19.4 μM) were required to inhibit redox cycling, presumably because of distinct mechanisms of sepiapterin reduction and redox cycling. In PC12 cells, which generate catecholamine and monoamine neurotransmitters via BH4-dependent amino acid hydroxylases, sulfa drugs inhibited both BH2/BH4 biosynthesis and redox cycling mediated by SPR. Inhibition of BH2/BH4 resulted in decreased production of dopamine and dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, and 5-hydroxytryptamine. Sulfathiazole (200 μM) markedly suppressed neurotransmitter production, an effect reversed by BH4. These data suggest that SPR and BH4-dependent enzymes, are “off-targets” of sulfa drugs, which may underlie their untoward effects. The ability of the sulfa drugs to inhibit redox cycling may ameliorate ROS-mediated toxicity generated by redox active drugs and chemicals, contributing to their anti-inflammatory activity. PMID:25550200

  8. Sulfa drugs inhibit sepiapterin reduction and chemical redox cycling by sepiapterin reductase.

    PubMed

    Yang, Shaojun; Jan, Yi-Hua; Mishin, Vladimir; Richardson, Jason R; Hossain, Muhammad M; Heindel, Ned D; Heck, Diane E; Laskin, Debra L; Laskin, Jeffrey D

    2015-03-01

    Sepiapterin reductase (SPR) catalyzes the reduction of sepiapterin to dihydrobiopterin (BH2), the precursor for tetrahydrobiopterin (BH4), a cofactor critical for nitric oxide biosynthesis and alkylglycerol and aromatic amino acid metabolism. SPR also mediates chemical redox cycling, catalyzing one-electron reduction of redox-active chemicals, including quinones and bipyridinium herbicides (e.g., menadione, 9,10-phenanthrenequinone, and diquat); rapid reaction of the reduced radicals with molecular oxygen generates reactive oxygen species (ROS). Using recombinant human SPR, sulfonamide- and sulfonylurea-based sulfa drugs were found to be potent noncompetitive inhibitors of both sepiapterin reduction and redox cycling. The most potent inhibitors of sepiapterin reduction (IC50s = 31-180 nM) were sulfasalazine, sulfathiazole, sulfapyridine, sulfamethoxazole, and chlorpropamide. Higher concentrations of the sulfa drugs (IC50s = 0.37-19.4 μM) were required to inhibit redox cycling, presumably because of distinct mechanisms of sepiapterin reduction and redox cycling. In PC12 cells, which generate catecholamine and monoamine neurotransmitters via BH4-dependent amino acid hydroxylases, sulfa drugs inhibited both BH2/BH4 biosynthesis and redox cycling mediated by SPR. Inhibition of BH2/BH4 resulted in decreased production of dopamine and dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, and 5-hydroxytryptamine. Sulfathiazole (200 μM) markedly suppressed neurotransmitter production, an effect reversed by BH4. These data suggest that SPR and BH4-dependent enzymes, are "off-targets" of sulfa drugs, which may underlie their untoward effects. The ability of the sulfa drugs to inhibit redox cycling may ameliorate ROS-mediated toxicity generated by redox active drugs and chemicals, contributing to their anti-inflammatory activity. PMID:25550200

  9. Isonicotinic acid hydrazide: an anti-tuberculosis drug inhibits malarial transmission in the mosquito gut.

    PubMed

    Arai, Meiji; Alavi, Yasmene I H; Mendoza, Jacqueline; Billker, Oliver; Sinden, Robert E

    2004-01-01

    We studied the transmission-blocking effect of isonicotinic acid hydrazide (INH), a widely used anti-tuberculosis drug, against Plasmodium gallinaceum and Plasmodium berghei. INH-treatment of infected animals did not inhibit parasite development in the blood of the vertebrate host, but did inhibit exflagellation, ookinete formation, and oocyst development in the mosquito. Oocyst development was inhibited in a dose-dependent manner. The ED(50) in the P. gallinaceum/chicken/Aedes aegypti model and P. berghei/mouse/Anopheles stephensi model was 72 and 109 mg/kg, respectively. In marked contrast, in vitro exflagellation and ookinete development were not directly affected by physiological concentrations of INH. We suggest that INH exerts its inhibitory effects on the mosquito stages of the malaria parasite by an indirect, and at present undefined mechanism. Further elucidation of the mechanism how INH inhibits parasite development specifically on mosquito stages may allow us to identify new targets for malaria control strategy. PMID:15013786

  10. The current status of time dependent CYP inhibition assay and in silico drug-drug interaction predictions.

    PubMed

    Yan, Zhengyin; Caldwell, Gary W

    2012-01-01

    Various CYP time-dependent inhibition (TDI) assays have been widely implemented in drug discovery and development which has led to great success in positively identifying compounds with mechanism-base inhibition liability. However, drug-drug interaction (DDI) predictions by various in-silico models utilizing kinetic parameters obtained from TDI assays have met with significant challenges including questionable kinetic data, over-simplified in-vitro models and unreliable mathematic algorithms. Although significant efforts have been made to standardize the TDI assay and refine mathematical models, recent evaluation studies have revealed that the kinetic parameters of TDI, the most important in-vitro data required by all DDI prediction models, are significantly impacted by a variety of experimental variables including microsomal protein concentration, metabolic stability, CYP-specific probes, and post-incubation time. This review attempts to provide medicinal chemists a brief overview on the current status of TDI assays, determination of kinetic parameters and in silico DDI predictions with emphasis on the complexity of the TDI kinetics and limitations of current in-vitro models and DDI prediction methodologies. PMID:22571791

  11. Inhibition of topoisomerase I activity and efflux drug transporters' expression by xanthohumol. from hops.

    PubMed

    Lee, Sung Ho; Kim, Hyun Jung; Lee, Jung Sun; Lee, Ik-Soo; Kang, Bok Yun

    2007-11-01

    Xanthohumol (XN) and its related compounds were evaluated for their cytotoxicity against four different human cancer cell lines, A549 (lung), SK-OV-3 (ovarian), SK-MEL-2 (melanoma), and HCT-15 (colon) using a sulforhodamine B assay. XN showed the most active cytotoxicity against the human cancer cell lines. Isoxanthohumol, 8-prenylnaringenin, and xanthohumol 4'-O-beta-D-glucopyranoside showed comparable cytotoxicity and (2S)-5-methoxy-8-prenylnaringenin 7-O-beta-D-glucopyranoside was the least cytotoxic compound. The anticancer properties of XN, the most active cytotoxic compound, were further investigated. XN showed an inhibitory effect on the activity of DNA topoisomerase I (topo I), which was measured from the relaxation of supercoiled DNA. The inhibition of topo I by XN might explain the cytotoxicity against the human cancer cell lines. Moreover, the expression of the drug efflux genes was investigated to predict the drug resistance. XN clearly decreased the mRNA levels of ABCB1 (MDR1), ABCC1 (MRP1), ABCC2 (MRP2), and ABCC3 (MRP3). These results suggest that XN has anticancer properties by inhibiting the topo I activity and it might be used in conjunction with other anticancer chemotherapeutic agents to reduce the drug resistance inhibiting the efflux drug transporters. PMID:18087812

  12. Mechanisms of cell death pathway activation following drug-induced inhibition of mitochondrial complex I

    PubMed Central

    Imaizumi, Naoki; Kwang Lee, Kang; Zhang, Carmen; Boelsterli, Urs A.

    2015-01-01

    Respiratory complex I inhibition by drugs and other chemicals has been implicated as a frequent mode of mitochondria-mediated cell injury. However, the exact mechanisms leading to the activation of cell death pathways are incompletely understood. This study was designed to explore the relative contributions to cell injury of three distinct consequences of complex I inhibition, i.e., impairment of ATP biosynthesis, increased formation of superoxide and, hence, peroxynitrite, and inhibition of the mitochondrial protein deacetylase, Sirt3, due to imbalance of the NADH/NAD+ ratio. We used the antiviral drug efavirenz (EFV) to model drug-induced complex I inhibition. Exposure of cultured mouse hepatocytes to EFV resulted in a rapid onset of cell injury, featuring a no-effect level at 30 µM EFV and submaximal effects at 50 µM EFV. EFV caused a concentration-dependent decrease in cellular ATP levels. Furthermore, EFV resulted in increased formation of peroxynitrite and oxidation of mitochondrial protein thiols, including cyclophilin D (CypD). This was prevented by the superoxide scavenger, Fe-TCP, or the peroxynitrite decomposition catalyst, Fe-TMPyP. Both ferroporphyrins completely protected from EFV-induced cell injury, suggesting that peroxynitrite contributed to the cell injury. Finally, EFV increased the NADH/NAD+ ratio, inhibited Sirt3 activity, and led to hyperacetylated lysine residues, including those in CypD. However, hepatocytes isolated from Sirt3-null mice were protected against 40 µM EFV as compared to their wild-type controls. In conclusion, these data are compatible with the concept that chemical inhibition of complex I activates multiple pathways leading to cell injury; among these, peroxynitrite formation may be the most critical. PMID:25625582

  13. Esterase inhibition attribute of grapefruit juice leading to a new drug interaction.

    PubMed

    Li, Ping; Callery, Patrick S; Gan, Liang-Shang; Balani, Suresh K

    2007-07-01

    This report describes a newly identified potential of grapefruit juice (GFJ) in mediating pharmacokinetic drug interactions due to its capability to inhibit esterase. The study demonstrates that GFJ inhibits purified porcine esterase activity toward p-nitrophenyl acetate and the prodrugs lovastatin and enalapril. In rat and human hepatic or gut S9 fractions and rat gut lumen, GFJ inhibited the hydrolysis of enalapril and lovastatin, which are known to be metabolized principally by esterases, lovastatin being metabolized also by CYP3A. In Caco-2 cells, with minimal CYP3A activity, permeability of these prodrugs was increased in the presence of GFJ. In rats, oral coadministration of GFJ or an esterase inhibitor, bis-(p-nitrophenylphosphate), with the prodrugs led to respective increases in plasma area under the curve by 70% or 57% for enalaprilat and 279% or 141% for lovastatin acid. In addition, portal vein-cannulated rats pretreated with GFJ at -15 and -2 h before lovastatin administration (10 mg/kg p.o.) as a solution, 1) in water and 2) in GFJ, showed, respectively, a 49% increase (CYP3A-inhibited) and a 116% increase (both CYP3A and gut esterase-inhibited) in the portal plasma exposure to the active acid, compared with a non-GFJ pretreatment group. Overall, along with the CYP3A inactivation by GFJ, the decreased esterase activity also played a significant role in increasing the metabolic stability and permeability of esters leading to enhancement of exposure to the active drugs in rats. These new esterase inhibition findings indicate that the potential of drug interaction between ester prodrugs and GFJ should also be considered in the clinic. PMID:17392396

  14. Fruit juice inhibition of uptake transport: a new type of food–drug interaction

    PubMed Central

    Bailey, David G

    2010-01-01

    A new type of interaction in which fruit juices diminish oral drug bioavailability through inhibition of uptake transport is the focus of this review. The discovery was based on an opposite to anticipated finding when assessing the possibility of grapefruit juice increasing oral fexofenadine bioavailability in humans through inhibition of intestinal MDR1-mediated efflux transport. In follow-up investigations, grapefruit or orange juice at low concentrations potentially and selectively inhibited in vitro OATP1A2-mediated uptake compared with MDR1-caused efflux substrate transport. These juices at high volume dramatically depressed oral fexofenadine bioavailability. Grapefruit was the representative juice to characterize the interaction subsequently. A volume–effect relationship study using a normal juice amount halved average fexofenadine absorption. Individual variability and reproducibility data indicated the clinical interaction involved direct inhibition of intestinal OATP1A2. Naringin was a major causal component suggesting that other flavonoids in fruits and vegetables might also produce the effect. Duration of juice clinical inhibition of fexofenadine absorption lasted more than 2 h but less than 4 h indicating the interaction was avoidable with appropriate interval of time between juice and drug consumption. Grapefruit juice lowered the oral bioavailability of several medications transported by OATP1A2 (acebutolol, celiprolol, fexofenadine, talinolol, L-thyroxine) while orange juice did the same for others (atenolol, celiprolol, ciprofloxacin, fexofenadine). Juice clinical inhibition of OATP2B1 was unresolved while that of OATP1B1 seemed unlikely. The interaction between grapefruit juice and etoposide also seemed relevant. Knowledge of both affected uptake transporter and drug hydrophilicity assisted prediction of the clinical interaction with grapefruit or orange juice. PMID:21039758

  15. Modulation of insulin/IGFs pathways by sirtuin-7 inhibition in drug-induced chemoreistance

    PubMed Central

    2014-01-01

    Background Insulin and insulin-like growth factors (IGFs) are key regulators of metabolism and growth. Recent evidences suggest a key role of these pathways in non-classical tissues and the metabolic pathways by which these hormones exert their effects in neoplasia is unclear. Aims To study insulin/IGFs pathways in drug sensitive and resistant cancer cells representing breast cancer (MCF-7), osteosarcoma (SaOS-2), and ovarian cancer (A2780) and to examine the effect of Sirtuin-7 (Sirt7) inhibition on insulin/IGFs pathways in MCF-7 cell line. Methods Drug resistant cells were generated by continuous incubation of parental cell lines with stepwise increases in Doxorubicin or Cisplatin over a period of 3 to 6 months. MCF-7 cells were transfected with cloned hairpin siRNA template for Sirt7 using the Amaxa GmbH transfection system. mRNA expression of Sirt7, INSR, IRS-1, IRS-2, IRS-4, IGF-1, IGF-2, MDR-1, MRP-1, BCRP was measured by qPCR and Sirt7 by standard Western blotting. FITC-insulin uptake was imaged with Leica Confocal Microscope. Results Insulin receptor (INSR), insulin receptor substrate-1 (IRS-1) were inhibited in drug-induced resistance, whereas IRS-2 was significantly induced in all the chemoresistant cells tested when compared to their parental counterparts. IGF-1 and IGF-2 were also upregulated in all the drug resistant cells tested. Sirt7 was significantly reduced in all chemoresistant cells tested. Knockdown of Sirt7 expression in human breast MCF-7 cell line by siRNA induced premature senescence-like phenotype and multi-drug resistance, suggesting that this gene may play an active role in regulating cancer cell response to stress. Suppression of Sirt7 selectively inhibited INSR and IRS-1, whereas it had minimal effect on that of IRS-2. Sirt7 suppression in MCF-7 also inhibited insulin uptake. Additionally, Sirt7 inhibition upregulated IGF-1, IGF-2 and IGFR expression. Conclusion Our data demonstrate that stress-induced Sirt7 inhibition significantly

  16. Mechanisms Underlying Food-Drug Interactions: Inhibition of Intestinal Metabolism and Transport

    PubMed Central

    Won, Christina S.; Oberlies, Nicholas H.; Paine, Mary F.

    2012-01-01

    Food-drug interaction studies are critical to evaluate appropriate dosing, timing, and formulation of new drug candidates. These interactions often reflect prandial-associated changes in the extent and/or rate of systemic drug exposure. Physiologic and physicochemical mechanisms underlying food effects on drug disposition are well-characterized. However, biochemical mechanisms involving drug metabolizing enzymes and transport proteins remain underexplored. Several plant-derived beverages have been shown to modulate enzymes and transporters in the intestine, leading to altered pharmacokinetic (PK) and potentially negative pharmacodynamic (PD) outcomes. Commonly consumed fruit juices, teas, and alcoholic drinks contain phytochemicals that inhibit intestinal cytochrome P450 and phase II conjugation enzymes, as well as uptake and efflux transport proteins. Whereas myriad phytochemicals have been shown to inhibit these processes in vitro, translation to the clinic has been deemed insignificant or undetermined. An overlooked prerequisite for elucidating food effects on drug PK is thorough knowledge of causative bioactive ingredients. Substantial variability in bioactive ingredient composition and activity of a given dietary substance poses a challenge in conducting robust food-drug interaction studies. This confounding factor can be addressed by identifying and characterizing specific components, which could be used as marker compounds to improve clinical trial design and quantitatively predict food effects. Interpretation and integration of data from in vitro, in vivo, and in silico studies require collaborative expertise from multiple disciplines, from botany to clinical pharmacology (i.e., plant to patient). Development of more systematic methods and guidelines is needed to address the general lack of information on examining drug-dietary substance interactions prospectively. PMID:22884524

  17. Mechanisms of hematin crystallization and inhibition by the antimalarial drug chloroquine.

    PubMed

    Olafson, Katy N; Ketchum, Megan A; Rimer, Jeffrey D; Vekilov, Peter G

    2015-04-21

    Hematin crystallization is the primary mechanism of heme detoxification in malaria parasites and the target of the quinoline class of antimalarials. Despite numerous studies of malaria pathophysiology, fundamental questions regarding hematin growth and inhibition remain. Among them are the identity of the crystallization medium in vivo, aqueous or organic; the mechanism of crystallization, classical or nonclassical; and whether quinoline antimalarials inhibit crystallization by sequestering hematin in the solution, or by blocking surface sites crucial for growth. Here we use time-resolved in situ atomic force microscopy (AFM) and show that the lipid subphase in the parasite may be a preferred growth medium. We provide, to our knowledge, the first evidence of the molecular mechanisms of hematin crystallization and inhibition by chloroquine, a common quinoline antimalarial drug. AFM observations demonstrate that crystallization strictly follows a classical mechanism wherein new crystal layers are generated by 2D nucleation and grow by the attachment of solute molecules. We identify four classes of surface sites available for binding of potential drugs and propose respective mechanisms of drug action. Further studies reveal that chloroquine inhibits hematin crystallization by binding to molecularly flat {100} surfaces. A 2-μM concentration of chloroquine fully arrests layer generation and step advancement, which is ∼10(4)× less than hematin's physiological concentration. Our results suggest that adsorption at specific growth sites may be a general mode of hemozoin growth inhibition for the quinoline antimalarials. Because the atomic structures of the identified sites are known, this insight could advance the future design and/or optimization of new antimalarials. PMID:25831526

  18. Esterase inhibition by grapefruit juice flavonoids leading to a new drug interaction.

    PubMed

    Li, Ping; Callery, Patrick S; Gan, Liang-Shang; Balani, Suresh K

    2007-07-01

    Our previous studies described a newly identified potential of grapefruit juice (GFJ) in mediating pharmacokinetic drug interactions due to its capability of esterase inhibition. The current study identifies the active components in GFJ responsible for its esterase-inhibitory effect. The esterase-inhibitory potential of 10 constitutive flavonoids and furanocoumarins toward p-nitrophenylacetate (PNPA) hydrolysis was investigated. The furanocoumarins bergamottin, 6',7'-dihydroxybergamottin, and bergapten, and the glycoside flavonoids naringin and hesperidin, at concentrations found in GFJ or higher, did not inhibit the hydrolysis of PNPA by purified porcine esterase and human liver microsomes. However, the flavonoid aglycones morin, galangin, kaempferol, quercetin, and naringenin showed appreciable inhibition of PNPA hydrolysis in purified porcine esterase, and human and rat liver systems. In Caco-2 cells, demonstrated to contain minimal CYP3A activity, the permeability coefficient of the prodrugs lovastatin and enalapril was increased in the presence of the active flavonoids kaempferol and naringenin, consistent with inhibition of esterase activity. In rats, oral coadministration of kaempferol and naringenin with these prodrugs led to significant increases in plasma exposure to the active acids. In addition, in portal vein-cannulated rats, coadministration of lovastatin with kaempferol (10 mg/kg) led to a 154% and a 113% increase in the portal plasma exposure to the prodrug and active acid, respectively, compared with coadministration with water. The contribution of CYP3A inhibition was demonstrated to be minimal. Overall, a series of flavonoids present in GFJ are identified as esterase inhibitors, of which kaempferol and naringenin are shown to mediate pharmacokinetic drug interaction with the prodrugs lovastatin and enalapril due to their capability of esterase inhibition. PMID:17452418

  19. BSEP inhibition: in vitro screens to assess cholestatic potential of drugs.

    PubMed

    Kis, Emese; Ioja, Enikő; Rajnai, Zsuzsa; Jani, Márton; Méhn, Dóra; Herédi-Szabó, Krisztina; Krajcsi, Peter

    2012-12-01

    Bile salt export pump (BSEP, ABC11) is a membrane protein that is localized in the cholesterol-rich canalicular membrane of hepatocytes. Its function is to eliminate unconjugated and conjugated bile acids/salts from hepatocyte into the bile. In humans there is no compensatory mechanism for the loss of this transporter. Mutations of BSEP result in a genetic disease, called progressive familial intrahepatic cholestasis type 2 (PFIC2), that is characterized with decreased biliary bile salt secretion, leading to decreased bile flow and accumulation of bile salts inside the hepatocyte, inflicting damage. BSEP inhibitor drugs produce similar bile salt retention that may lead to severe cholestasis and liver damage. Drug-induced liver injury is a relevant clinical issue, in severe cases ending in liver transplantation. Therefore, measurement of BSEP inhibition by candidate drugs has high importance in drug discovery and development. Although several methods are suitable to detect BSEP-drug interactions, due to interspecies differences in bile acid composition, differences in hepatobiliary transporter modulation, they have limitations. This review summarizes appropriate in vitro methods that could be able to predict BSEP-drug candidate interactions in humans before the start of clinical phases. PMID:22120137

  20. Cardiotoxicity of copper-based antineoplastic drugs casiopeinas is related to inhibition of energy metabolism

    SciTech Connect

    Hernandez-Esquivel, Luz; Marin-Hernandez, Alvaro; Pavon, Natalia; Carvajal, Karla; Moreno-Sanchez, Rafael . E-mail: rafael.moreno@cardiologia.org.mx

    2006-04-01

    Isolated rat hearts were perfused with glucose, octanoate or glucose + octanoate and different concentrations of the copper-based antineoplastic drugs casiopeina II-gly (CSII) or casiopeina III-i-a (CSIII). In isolated perfused hearts with glucose + octanoate, both casiopeinas induced diminution in cardiac work and O{sub 2} consumption with half-maximal inhibitory concentrations (IC{sub 5}) of 4 (CSII) and 4.6 (CSIII) {mu}M, after 1 h of perfusion. Strong inhibition of the pyruvate and 2-oxoglutarate dehydrogenases as well as total creatine kinase by casiopeinas suggested that ATP generation by oxidative phosphorylation and its transfer towards myofibrils were targets for these drugs. In consequence, the cellular contents of ATP and phosphocreatine were also lowered by casiopeinas. Remarkably, casiopeinas were less toxic than adriamycin (IC{sub 5} = 2.6 {mu}M), a well-known potent cardiotoxic and antineoplastic drug, which has a wide clinical use. In an open-chest animal, which is a more physiological model than the isolated heart, femoral administration of 1 {mu}M drug revealed that CSII was innocuous very likely due to strong binding to serum albumin, whereas adriamycin induced again a potent cardiotoxic effect (diminution in heart rate and severe depression of systolic blood pressure). Thus, it seems that casiopeinas are a group of new antineoplastic drugs with milder secondary toxic effects than proven drugs such as adriamycin.

  1. Inhibiting Drivers of Non-mutational Drug Tolerance Is a Salvage Strategy for Targeted Melanoma Therapy.

    PubMed

    Smith, Michael P; Brunton, Holly; Rowling, Emily J; Ferguson, Jennifer; Arozarena, Imanol; Miskolczi, Zsofia; Lee, Jessica L; Girotti, Maria R; Marais, Richard; Levesque, Mitchell P; Dummer, Reinhard; Frederick, Dennie T; Flaherty, Keith T; Cooper, Zachary A; Wargo, Jennifer A; Wellbrock, Claudia

    2016-03-14

    Once melanomas have progressed with acquired resistance to mitogen-activated protein kinase (MAPK)-targeted therapy, mutational heterogeneity presents a major challenge. We therefore examined the therapy phase before acquired resistance had developed and discovered the melanoma survival oncogene MITF as a driver of an early non-mutational and reversible drug-tolerance state, which is induced by PAX3-mediated upregulation of MITF. A drug-repositioning screen identified the HIV1-protease inhibitor nelfinavir as potent suppressor of PAX3 and MITF expression. Nelfinavir profoundly sensitizes BRAF and NRAS mutant melanoma cells to MAPK-pathway inhibitors. Moreover, nelfinavir is effective in BRAF and NRAS mutant melanoma cells isolated from patients progressed on MAPK inhibitor (MAPKi) therapy and in BRAF/NRAS/PTEN mutant tumors. We demonstrate that inhibiting a driver of MAPKi-induced drug tolerance could improve current approaches of targeted melanoma therapy. PMID:26977879

  2. Mechanism of human telomerase inhibition by BIBR1532, a synthetic, non-nucleosidic drug candidate.

    PubMed

    Pascolo, Emanuelle; Wenz, Christian; Lingner, Joachim; Hauel, Norbert; Priepke, Henning; Kauffmann, Iris; Garin-Chesa, Pilar; Rettig, Wolfgang J; Damm, Klaus; Schnapp, Andreas

    2002-05-01

    Telomerase, a ribonucleoprotein acting as a reverse transcriptase, has been identified as a target for cancer drug discovery. The synthetic, non-nucleosidic compound, BIBR1532, is a potent and selective telomerase inhibitor capable of inducing senescence in human cancer cells (). In the present study, the mode of drug action was characterized. BIBR1532 inhibits the native and recombinant human telomerase, comprising the human telomerase reverse transcriptase and human telomerase RNA components, with similar potency primarily by interfering with the processivity of the enzyme. Enzyme-kinetic experiments show that BIBR1532 is a mixed-type non-competitive inhibitor and suggest a drug binding site distinct from the sites for deoxyribonucleotides and the DNA primer, respectively. Thus, BIBR1532 defines a novel class of telomerase inhibitor with mechanistic similarities to non-nucleosidic inhibitors of HIV1 reverse transcriptase. PMID:11854300

  3. Inhibiting Drivers of Non-mutational Drug Tolerance Is a Salvage Strategy for Targeted Melanoma Therapy

    PubMed Central

    Smith, Michael P.; Brunton, Holly; Rowling, Emily J.; Ferguson, Jennifer; Arozarena, Imanol; Miskolczi, Zsofia; Lee, Jessica L.; Girotti, Maria R.; Marais, Richard; Levesque, Mitchell P.; Dummer, Reinhard; Frederick, Dennie T.; Flaherty, Keith T.; Cooper, Zachary A.; Wargo, Jennifer A.; Wellbrock, Claudia

    2016-01-01

    Summary Once melanomas have progressed with acquired resistance to mitogen-activated protein kinase (MAPK)-targeted therapy, mutational heterogeneity presents a major challenge. We therefore examined the therapy phase before acquired resistance had developed and discovered the melanoma survival oncogene MITF as a driver of an early non-mutational and reversible drug-tolerance state, which is induced by PAX3-mediated upregulation of MITF. A drug-repositioning screen identified the HIV1-protease inhibitor nelfinavir as potent suppressor of PAX3 and MITF expression. Nelfinavir profoundly sensitizes BRAF and NRAS mutant melanoma cells to MAPK-pathway inhibitors. Moreover, nelfinavir is effective in BRAF and NRAS mutant melanoma cells isolated from patients progressed on MAPK inhibitor (MAPKi) therapy and in BRAF/NRAS/PTEN mutant tumors. We demonstrate that inhibiting a driver of MAPKi-induced drug tolerance could improve current approaches of targeted melanoma therapy. PMID:26977879

  4. Inhibition of Microglia Activation as a Phenotypic Assay in Early Drug Discovery

    PubMed Central

    Figuera-Losada, Mariana; Rojas, Camilo; Slusher, Barbara S.

    2014-01-01

    Complex biological processes such as inflammation, cell death, migration, proliferation, and the release of biologically active molecules can be used as outcomes in phenotypic assays during early stages of drug discovery. Although target-based approaches have been widely used over the past decades, a disproportionate number of first-in-class drugs have been identified using phenotypic screening. This review details phenotypic assays based on inhibition of microglial activation and their utility in primary and secondary screening, target validation, and pathway elucidation. The role of microglia, both in normal as well as in pathological conditions such as chronic neurodegenerative diseases, is reviewed. Methodologies to assess microglia activation in vitro are discussed in detail, and classes of therapeutic drugs known to decrease the proinflammatory and cytotoxic responses of activated microglia are appraised, including inhibitors of glutaminase, cystine/glutamate antiporter, nuclear factor κB, and mitogen-activated protein kinases. PMID:23945875

  5. Point-of-care platelet function tests: detection of platelet inhibition induced by nonopioid analgesic drugs.

    PubMed

    Scharbert, Gisela; Gebhardt, Kristina; Sow, Zacharia; Duris, Monika; Deusch, Engelbert; Kozek-Langenecker, Sibylle

    2007-12-01

    Detection of platelet inhibition is of clinical relevance in the preinterventional risk-benefit assessment in chronic low-back-pain patients scheduled for invasive pain therapy. We evaluated the sensitivity of various point-of-care platelet function tests for the detection of platelet inhibition induced by nonopioid analgesic drugs. After Institutional Review Board approval and informed consent, citrated whole blood from 40 patients with chronic unspecific low back pain was investigated before and 30 min after intravenous infusion of the study medication consisting of diclofenac 75 mg (plus orphenadrin 30 mg; Neodolpasse; Fresenius Kabi Austria GmbH, Austria), parecoxib 40 mg (Dynastat; Pharmacia Europe EEIG, UK), paracetamol 1 g (Perfalgan; Bieffe Medital S.P.A., Italy), or normal saline in a randomized, cross-over, double-blinded, placebo-controlled study. Platelet function was assessed using the PFA-100 platelet function analyzer and thromboelastometry, as well as impedance aggregometry (in the last 17 patients recruited after it became commercially available). Sensitivity for detecting diclofenac-induced platelet inhibition was 85% for the PFA-100 using epinephrine as agonist and 94% for arachidonic acid-induced impedance aggregometry. ADP-induced platelet function tests, as well as cytochalasin D-modified thromboelastometry were unreliable. All tests had a low incidence of false-positive test results after normal saline. Paracetamol and parecoxib had no significant platelet inhibiting effect. The PFA-100 using epinephrine as agonist and arachidonic acid-induced impedance aggregometry are recommended for the detection of cyclooxygenase-I-inhibiting effects of nonsteroidal anti-inflammatory drugs such as diclofenac. Our findings confirm that a single rescue dose of paracetamol and parecoxib has no antiplatelet effect. PMID:17982319

  6. Inhibition of endosomal sequestration of basic anticancer drugs: influence on cytotoxicity and tissue penetration

    PubMed Central

    Lee, C M; Tannock, I F

    2006-01-01

    The basic drugs doxorubicin and mitoxantrone are known to be concentrated in acidic endosomes of cells. Here, we address the hypotheses that raising endosomal pH with the modifying agents chloroquine, omeprazole or bafilomycin A might decrease sequestration of anticancer drugs in endosomes, thereby increasing their cytotoxicity and availability for tissue penetration. Chloroquine, omeprazole and bafilomycin A showed concentration-dependent effects to raise endosomal pH, and to inhibit sequestration of doxorubicin in endosomes. Chloroquine and omeprazole but not bafilomycin A decreased the net uptake of doxorubicin into cells, but there was no significant effect on uptake of mitoxantrone. Omeprazole and bafilomycin A increased the cytotoxicity of the anticancer drugs for cultured cells, as measured in a clonogenic assay, whereas chloroquine had minimal effects on cytotoxicity despite reduced uptake of doxorubicin. Omeprazole but not chloroquine or bafilomycin A increased the penetration of anticancer drugs through multicellular layers of tumour tissue. We conclude that modifiers of endosomal pH might increase therapeutic effectiveness of basic drugs by increasing their toxicity and/or tissue penetration in solid tumours. PMID:16495919

  7. Ultrasound triggered image-guided drug delivery to inhibit vascular reconstruction via paclitaxel-loaded microbubbles

    PubMed Central

    Zhu, Xu; Guo, Jun; He, Cancan; Geng, Huaxiao; Yu, Gengsheng; Li, Jinqing; Zheng, Hairong; Ji, Xiaojuan; Yan, Fei

    2016-01-01

    Paclitaxel (PTX) has been recognized as a promising drug for intervention of vascular reconstructions. However, it is still difficult to achieve local drug delivery in a spatio-temporally controllable manner under real-time image guidance. Here, we introduce an ultrasound (US) triggered image-guided drug delivery approach to inhibit vascular reconstruction via paclitaxel (PTX)-loaded microbubbles (PLM) in a rabbit iliac balloon injury model. PLM was prepared through encapsulating PTX in the shell of lipid microbubbles via film hydration and mechanical vibration technique. Our results showed PLM could effectively deliver PTX when exposed to US irradiation and result in significantly lower viability of vascular smooth muscle cells. Ultrasonographic examinations revealed the US signals from PLM in the iliac artery were greatly increased after intravenous administration of PLM, making it possible to identify the restenosis regions of iliac artery. The in vivo anti-restenosis experiments with PLM and US greatly inhibited neointimal hyperplasia at the injured site, showing an increased lumen area and reduced the ratio of intima area and the media area (I/M ratio). No obvious functional damages to liver and kidney were observed for those animals. Our study provided a promising approach to realize US triggered image-guided PTX delivery for therapeutic applications against iliac restenosis. PMID:26899550

  8. Anthocyanidins but not anthocyanins inhibit P-glycoprotein-mediated calcein extrusion - possible implication for orally administered drugs.

    PubMed

    Vrzal, Radim

    2016-06-01

    P-glycoprotein (P-gp) inhibition represents a promising therapeutic strategy for oncologic patients. The inhibition by naturally occurring anthocyans would bring certain benefits. Unfortunately, due to the low bioavailability and consequently low blood level, they cannot be used for cancer therapy. However, due to the food supplementation, significant concentration can raise up in the intestine, where P-gp is abundantly expressed. As many drugs are orally taken, simultaneous administration might affect the concentration of these drugs in the blood. Here, we found that anthocyanidins (aglycons) but not anthocyanins (glycosides) can significantly inhibit P-gp up to 60% of positive control, verapamil. This inhibitory activity was observed for 500 μm concentrations of malvidin and pelargonidin. We conclude that these compounds may be the source of food-drug interactions either for orally taken drugs or for intravenously administered drugs eliminated via biliary excretion which are the substrates of P-gp. PMID:26821071

  9. Sodium channel-inhibiting drugs and survival of breast, colon and prostate cancer: a population-based study

    PubMed Central

    Fairhurst, Caroline; Watt, Ian; Martin, Fabiola; Bland, Martin; Brackenbury, William J.

    2015-01-01

    Metastasis is the leading cause of cancer-related deaths. Voltage-gated sodium channels (VGSCs) regulate invasion and metastasis. Several VGSC-inhibiting drugs reduce metastasis in murine cancer models. We aimed to test the hypothesis that patients taking VGSC-inhibiting drugs who developed cancer live longer than those not taking these drugs. A cohort study was performed on primary care data from the QResearch database, including patients with breast, bowel or prostate cancer. Cox proportional hazards regression was used to compare the survival from cancer diagnosis of patients taking VGSC-inhibiting drugs with those not exposed to these drugs. Median time to death was 9.7 years in the exposed group and 18.4 years in the unexposed group, and exposure to these medications significantly increased mortality. Thus, exposure to VGSC-inhibiting drugs associates with reduced survival in breast, bowel and prostate cancer patients. This finding is not consistent with the preclinical data. Despite the strengths of this study including the large sample size, the study is limited by missing information on potentially important confounders such as cancer stage, co-morbidities and cause of death. Further research, which is able to account for these confounding issues, is needed to investigate the relationship between VGSC-inhibiting drugs and cancer survival. PMID:26577038

  10. The antiviral drug ganciclovir does not inhibit microglial proliferation and activation

    PubMed Central

    Skripuletz, Thomas; Salinas Tejedor, Laura; Prajeeth, Chittappen K.; Hansmann, Florian; Chhatbar, Chintan; Kucman, Valeria; Zhang, Ning; Raddatz, Barbara B.; Detje, Claudia N.; Sühs, Kurt-Wolfram; Pul, Refik; Gudi, Viktoria; Kalinke, Ulrich; Baumgärtner, Wolfgang; Stangel, Martin

    2015-01-01

    Ganciclovir is effective in the treatment of human infections with viruses of the Herpesviridae family. Beside antiviral properties, recently ganciclovir was described to inhibit microglial proliferation and disease severity of experimental autoimmune encephalomyelitis, an inflammatory model of multiple sclerosis. Microglial activation and proliferation are main characteristics of neuroinflammatory CNS diseases and inhibition of microglial functions might be beneficial in autoimmune diseases, or detrimental in infectious diseases. The objective of this study was to determine potential inhibitory effects of ganciclovir in three different murine animal models of CNS neuroinflammation in which microglia play an important role: Theiler´s murine encephalomyelitis, the cuprizone model of de- and remyelination, and the vesicular stomatitis virus encephalitis model. In addition, in vitro experiments with microglial cultures were performed to test the hypothesis that ganciclovir inhibits microglial proliferation. In all three animal models, neither microglial proliferation or recruitment nor disease activity was changed by ganciclovir. In vitro experiments confirmed that microglial proliferation was not affected by ganciclovir. In conclusion, our results show that the antiviral drug ganciclovir does not inhibit microglial activation and proliferation in the murine CNS. PMID:26447351

  11. The antiviral drug ganciclovir does not inhibit microglial proliferation and activation.

    PubMed

    Skripuletz, Thomas; Salinas Tejedor, Laura; Prajeeth, Chittappen K; Hansmann, Florian; Chhatbar, Chintan; Kucman, Valeria; Zhang, Ning; Raddatz, Barbara B; Detje, Claudia N; Sühs, Kurt-Wolfram; Pul, Refik; Gudi, Viktoria; Kalinke, Ulrich; Baumgärtner, Wolfgang; Stangel, Martin

    2015-01-01

    Ganciclovir is effective in the treatment of human infections with viruses of the Herpesviridae family. Beside antiviral properties, recently ganciclovir was described to inhibit microglial proliferation and disease severity of experimental autoimmune encephalomyelitis, an inflammatory model of multiple sclerosis. Microglial activation and proliferation are main characteristics of neuroinflammatory CNS diseases and inhibition of microglial functions might be beneficial in autoimmune diseases, or detrimental in infectious diseases. The objective of this study was to determine potential inhibitory effects of ganciclovir in three different murine animal models of CNS neuroinflammation in which microglia play an important role: Theiler´s murine encephalomyelitis, the cuprizone model of de- and remyelination, and the vesicular stomatitis virus encephalitis model. In addition, in vitro experiments with microglial cultures were performed to test the hypothesis that ganciclovir inhibits microglial proliferation. In all three animal models, neither microglial proliferation or recruitment nor disease activity was changed by ganciclovir. In vitro experiments confirmed that microglial proliferation was not affected by ganciclovir. In conclusion, our results show that the antiviral drug ganciclovir does not inhibit microglial activation and proliferation in the murine CNS. PMID:26447351

  12. Antibiotic drug tigecycline inhibited cell proliferation and induced autophagy in gastric cancer cells

    SciTech Connect

    Tang, Chunling; Yang, Liqun; Jiang, Xiaolan; Xu, Chuan; Wang, Mei; Wang, Qinrui; Zhou, Zhansong; Xiang, Zhonghuai; Cui, Hongjuan

    2014-03-28

    Highlights: • Tigecycline inhibited cell growth and proliferation in human gastric cancer cells. • Tigecycline induced autophagy not apoptosis in human gastric cancer cells. • AMPK/mTOR/p70S6K pathway was activated after tigecycline treatment. • Tigecycline inhibited tumor growth in xenograft model of human gastric cancer cells. - Abstract: Tigecycline acts as a glycylcycline class bacteriostatic agent, and actively resists a series of bacteria, specifically drug fast bacteria. However, accumulating evidence showed that tetracycline and their derivatives such as doxycycline and minocycline have anti-cancer properties, which are out of their broader antimicrobial activity. We found that tigecycline dramatically inhibited gastric cancer cell proliferation and provided an evidence that tigecycline induced autophagy but not apoptosis in human gastric cancer cells. Further experiments demonstrated that AMPK pathway was activated accompanied with the suppression of its downstream targets including mTOR and p70S6K, and ultimately induced cell autophagy and inhibited cell growth. So our data suggested that tigecycline might act as a candidate agent for pre-clinical evaluation in treatment of patients suffering from gastric cancer.

  13. Non Steroidal Anti Inflammatory Drugs As Gatekeepers Of Colon Carcinoma Highlight New Scenarios Beyond Cyclooxygenases Inhibition.

    PubMed

    Guarnieri, Tiziana

    2016-01-01

    Epidemiological data suggest that Non Steroidal Anti Inflammatory Drugs (NSAIDs) and Cyclooxygenase 2 (COX2) inhibitors (COXibs) can exert chemopreventive and antitumour effects in many human neoplasia. This is particularly true in colon cancer (CC), where the regular assumption of these molecules has been shown to exert chemopreventive and chemotherapeutic effects. Since the late '90s, there has been a progressive increase in experimental evidence, indicating that in CC the antiproliferative effects of NSAIDs and COXibs could be both dependent on and independent of COXs inhibition, and that these effects do not necessarily exclude each other. This review will examine some of these COX-independent cellular pathways, with a focus on those involved in the inhibition of CC cells proliferation through transcription factors crosstalk. PMID:26310524

  14. Glipizide, an antidiabetic drug, suppresses tumor growth and metastasis by inhibiting angiogenesis.

    PubMed

    Qi, Cuiling; Zhou, Qin; Li, Bin; Yang, Yang; Cao, Liu; Ye, Yuxiang; Li, Jiangchao; Ding, Yi; Wang, Huiping; Wang, Jintao; He, Xiaodong; Zhang, Qianqian; Lan, Tian; Lee, Kenneth Ka Ho; Li, Weidong; Song, Xiaoyu; Zhou, Jia; Yang, Xuesong; Wang, Lijing

    2014-10-30

    Angiogenesis is involved in the development, progression and metastasis of various human cancers. Herein, we report the discovery of glipizide, a widely used drug for type 2 diabetes mellitus, as a promising anticancer agent through the inhibition of tumor angiogenesis. By high-throughput screening (HTS) of an FDA approved drug library utilizing our in vivo chick embryo chorioallantoic membrane (CAM) and yolk sac membrane (YSM) models, glipizide has been identified to significantly inhibit blood vessel formation and development. Moreover, glipizide was found to suppress tumor angiogenesis, tumor growth and metastasis using xenograft tumor and MMTV-PyMT transgenic mouse models. We further revealed that the anticancer capability of glipizide is not attributed to its antiproliferative effects, which are not significant against various human cancer cell lines. To investigate whether its anticancer efficacy is associated with the glucose level alteration induced by glipizide application, glimepiride, another medium to long-acting sulfonylurea antidiabetic drug in the same class, was employed for the comparison studies in the same fashion. Interestingly, glimepiride has demonstrated no significant impact on the tumor growth and metastasis, indicating that the anticancer effects of glipizide is not ascribed to its antidiabetic properties. Furthermore, glipizide suppresses endothelial cell migration and the formation of tubular structures, thereby inhibiting angiogenesis by up-regulating the expression of natriuretic peptide receptor A. These findings uncover a novel mechanism of glipizide as a potential cancer therapy, and also for the first time, provide direct evidence to support that treatment with glipizide may reduce the cancer risk for diabetic patients. PMID:25294818

  15. [A SOS induction test screening study for vegetables inhibiting mutagenicity caused by antineoplastic drugs].

    PubMed

    Zhao, Z Z; Huang, M T

    1992-03-01

    Using mutational and anti-mutational synchronous in SOS inductest (+/- S9), We found that 7 out of 11 kinds of commonly eaten vegetables had the ability to inhibit mutagenicity caused by chemical drugs such as Mitomycin C, Bleomycinia, Fluorouracil, Cis-Diaminodichloroplatinum, Arabinosylcytosin and mustargen, They were garlic, green Chinese onion, onion, garlic bulb, tomato, cucumber and water radish. The other 4 lacking this ability were rape, chinese toon, ginger and asparagus lettuce stalk. We believe that our results can be helpful in the preparation. of cancer patients' diet, who are receiving chemotherapy and in the prevention of cancer. PMID:1451586

  16. [Effects of psychotropic drugs on lateral hypothalamic self-stimulation behavior in rats: correlation between self-stimulation behavior inhibition and striatal dopaminergic blockade by neuroleptic drugs].

    PubMed

    Fukuda, T; Tsumagari, T

    1984-06-01

    The effects of neuroleptic drugs on self-stimulation behavior were investigated in rats with electrodes chronically implanted in the lateral hypothalamus. Except for sulpiride and carpipramine, the neuroleptic drugs chlorpromazine, thioridazine, perphenazine, haloperidol, floropipamide, pimozide, clocapramine and oxypertine all suppressed self-stimulation behavior dose-dependently. The anti-anxiety drugs chlordiazepoxide, diazepam, clotiazepam and etizolam facilitated this behavior. The antidepressant drugs imipramine and amitriptyline suppressed this behavior slightly at the dose of 40 mg/kg. The alpha-antagonist phenoxybenzamine also suppressed this behavior, but the slope of its dose-response curve was gentle compared with those of the neuroleptic drugs. The inhibition produced by the neuroleptic drugs is considered to be mediated primarily at the dopaminergic receptors. Turning behavior induced by methamphetamine in rats with unilateral 6-hydroxydopamine lesions of the caudate nucleus was used to assess the striatal dopaminergic blocking potency of the neuroleptic drugs. No correlation was found between the ED50 values for the turning behavior inhibition and the ED50 values for the self-stimulation behavior inhibition produced by these drugs, so the dopaminergic receptors in the striatum are apparently not involved in the mediation of self-stimulation behavior. PMID:6149172

  17. Drug CRL 40 028-induced inhibition of pancreatic secretion in rats.

    PubMed

    Rozé, C; Chariot, J; Vaille, C

    1983-09-01

    The drug CRL 40 028 increases spontaneous motility through an action on central adrenergic receptors. The effects of this drug have been tested in rats on the external pancreatic secretion induced by secretin, CCK, acetylcholine, vagal electrical stimulation or 2 deoxy-D-glucose. CRL 40 028 had no effect on basal secretion nor on secretion stimulated by agents acting directly on pancreatic secretory cells (secretin, CCK, acetylcholine), but decreased significantly secretion induced by central or peripheral stimulation of the vagus nerves. CRL 40 028-induced inhibition of 2 DG effect was reduced by yohimbine, suggesting a participation of alpha 2-adrenergic receptors in the action of CRL 40 028 on the exocrine pancreas secretion of rats. PMID:6139981

  18. Inhibition of cation channel function at the nicotinic acethylcholine receptor from Torpedo: Agonist self-inhibition and anesthetic drugs

    SciTech Connect

    Forman, S.A.

    1989-01-01

    Modulation of the nicotinic acethylcholine receptor from Torpedo by cholinergic agonists, local anesthetics, and n-alkanols was studied using {sup 86}Rb{sup +} flux studies in sealed native Torpedo electroplaque membrane vesicles. Reliable concentration-response and kinetic data were obtained using manual ten sec filtration assays in vesicles partially blocked with alpha-bungarotoxin to remove spare receptors and quenched-flow assays to assess initial {sup 86}Rb{sup +} flux rates or the rate of drug-induced receptor inactivation. Concentration response relationships for the agonists acetylcholine, carbamylcholine, suberyldicholine, phenyltrimethylammonium, and (-)-nicotine are all bell-shape due to stimulation of cation channel opening at low concentrations and inhibition of channels at higher concentrations. The rate of agonist-induced fast desensitization (k{sub d}) increases with (acetylcholine) in parallel with channel activation, suggesting that desensitization proceeds from the open state and/or states in rapid equilibrium with it. At self-inhibitory acetylcholine concentrations, a new rapid inactivation (rate = k{sub f}) is observed before fast desensitization. The rate and extent of rapid inactivation is compatible with bimolecular association between acethylcholine and inhibitory site with K{sub B} = 40 mM.

  19. Antidepressant drugs specifically inhibiting noradrenaline reuptake enhance recognition memory in rats.

    PubMed

    Feltmann, Kristin; Konradsson-Geuken, Åsa; De Bundel, Dimitri; Lindskog, Maria; Schilström, Björn

    2015-12-01

    Patients suffering from major depression often experience memory deficits even after the remission of mood symptoms, and many antidepressant drugs do not affect, or impair, memory in animals and humans. However, some antidepressant drugs, after a single dose, enhance cognition in humans (Harmer et al., 2009). To compare different classes of antidepressant drugs for their potential as memory enhancers, we used a version of the novel object recognition task in which rats spontaneously forget objects 24 hr after their presentation. Antidepressant drugs were injected systemically 30 min before or directly after the training phase (Session 1 [S1]). Post-S1 injections were used to test for specific memory-consolidation effects. The noradrenaline reuptake inhibitors reboxetine and atomoxetine, as well as the serotonin noradrenaline reuptake inhibitor duloxetine, injected prior to S1 significantly enhanced recognition memory. In contrast, the serotonin reuptake inhibitors citalopram and paroxetine and the cyclic antidepressant drugs desipramine and mianserin did not enhance recognition memory. Post-S1 injection of either reboxetine or citalopram significantly enhanced recognition memory, indicating an effect on memory consolidation. The fact that citalopram had an effect only when injected after S1 suggests that it may counteract its own consolidation-enhancing effect by interfering with memory acquisition. However, pretreatment with citalopram did not attenuate reboxetine's memory-enhancing effect. The D1/5-receptor antagonist SCH23390 blunted reboxetine's memory-enhancing effect, indicating a role of dopaminergic transmission in reboxetine-induced recognition memory enhancement. Our results suggest that antidepressant drugs specifically inhibiting noradrenaline reuptake enhance cognition and may be beneficial in the treatment of cognitive symptoms of depression. PMID:26501179

  20. Composite fiber structures with antiproliferative agents exhibit advantageous drug delivery and cell growth inhibition in vitro.

    PubMed

    Kraitzer, Amir; Kloog, Yoel; Haklai, Roni; Zilberman, Meital

    2011-01-01

    Composite core/shell fiber structures loaded with the antiproliferative drugs paclitaxel or farnesylthiosalicylate (FTS) were developed and studied. The latter is a specific nontoxic Ras inhibitor with a mild hydrophobic nature, which can also be used for local cancer treatment and stent applications. The fibers were composed of a dense polyglyconate core and a porous drug-loaded poly(D,L-lactic-glycolic acid) shell, prepared using freeze drying of inverted emulsions. Our study focused on the release profile of the antiproliferative drugs from the fibers, the shell morphology and its degradation and erosion. The postfabrication antiproliferative effect of the drugs was tested in a cell culture. The process parameters were found to affect the drug-release profile via two routes: (1) direct, through water uptake and swelling of the structure leading to FTS release, or through degradation of the host polymer leading to paclitaxel release at a later stage; (2) indirect effect of the microstructure on the release profile. The fabrication process did not reduce the pharmacological activity of either paclitaxel or FTS. FTS-eluting composite fibers proved to effectively induce growth inhibition or cell death by a gradient effect and dose-dependent manner. The combined effect of the targeted mechanism of FTS as a Ras inhibitor together with the localized and controlled release characteristics of the fiber is an advantageous antiproliferative quality. It is therefore suggested that our drug-eluting fibers may be used in biomedical applications that require short release (restenosis) or prolonged release (cancer therapy). PMID:20623695

  1. Inhibition of West Nile Virus Multiplication in Cell Culture by Anti-Parkinsonian Drugs

    PubMed Central

    Blázquez, Ana B.; Martín-Acebes, Miguel A.; Saiz, Juan-Carlos

    2016-01-01

    West Nile virus (WNV) is a mosquito-borne flavivirus maintained in a transmission cycle between mosquitoes and birds, but it can also infect other vertebrates, including humans, in which it can cause neuroinvasive diseases. To date, no licensed vaccine or therapy for human use against this pathogen is yet available. A recent approach to search for new antiviral agent candidates is the assessment of long-used drugs commonly administered by clinicians to treat human disorders in drug antiviral development. In this regard, as patients with West Nile encephalitis frequently develop symptoms and features of parkinsonism, and cellular factors altered in parkinsonism, such as alpha-synuclein, have been shown to play a role on WNV infection, we have assessed the effect of four drugs (L-dopa, Selegiline, Isatin, and Amantadine), that are used as therapy for Parkinson’s disease in the inhibition of WNV multiplication. L-dopa, Isatin, and Amantadine treatments significantly reduced the production of infectious virus in all cell types tested, but only Amantadine reduced viral RNA levels. These results point to antiparkinsonian drugs as possible therapeutic candidates for the development of antiviral strategies against WNV infection. PMID:27014219

  2. Inhibition of West Nile Virus Multiplication in Cell Culture by Anti-Parkinsonian Drugs.

    PubMed

    Blázquez, Ana B; Martín-Acebes, Miguel A; Saiz, Juan-Carlos

    2016-01-01

    West Nile virus (WNV) is a mosquito-borne flavivirus maintained in a transmission cycle between mosquitoes and birds, but it can also infect other vertebrates, including humans, in which it can cause neuroinvasive diseases. To date, no licensed vaccine or therapy for human use against this pathogen is yet available. A recent approach to search for new antiviral agent candidates is the assessment of long-used drugs commonly administered by clinicians to treat human disorders in drug antiviral development. In this regard, as patients with West Nile encephalitis frequently develop symptoms and features of parkinsonism, and cellular factors altered in parkinsonism, such as alpha-synuclein, have been shown to play a role on WNV infection, we have assessed the effect of four drugs (L-dopa, Selegiline, Isatin, and Amantadine), that are used as therapy for Parkinson's disease in the inhibition of WNV multiplication. L-dopa, Isatin, and Amantadine treatments significantly reduced the production of infectious virus in all cell types tested, but only Amantadine reduced viral RNA levels. These results point to antiparkinsonian drugs as possible therapeutic candidates for the development of antiviral strategies against WNV infection. PMID:27014219

  3. Structural Basis for Inhibition of Histamine N-Methyltransferase by Diverse Drugs

    SciTech Connect

    Horton,J.; Sawada, K.; Nishibori, M.; Cheng, X.

    2005-01-01

    In mammals, histamine action is terminated through metabolic inactivation by histamine N-methyltransferase (HNMT) and diamine oxidase. In addition to three well-studied pharmacological functions, smooth muscle contraction, increased vascular permeability, and stimulation of gastric acid secretion, histamine plays important roles in neurotransmission, immunomodulation, and regulation of cell proliferation. The histamine receptor H1 antagonist diphenhydramine, the antimalarial drug amodiaquine, the antifolate drug metoprine, and the anticholinesterase drug tacrine (an early drug for Alzheimer's disease) are surprisingly all potent HNMT inhibitors, having inhibition constants in the range of 10-100 nM. We have determined the structural mode of interaction of these four inhibitors with HNMT. Despite their structural diversity, they all occupy the histamine-binding site, thus blocking access to the enzyme's active site. Near the N terminus of HNMT, several aromatic residues (Phe9, Tyr15, and Phe19) adopt different rotamer conformations or become disordered in the enzyme-inhibitor complexes, accommodating the diverse, rigid hydrophobic groups of the inhibitors. The maximized shape complementarity between the protein aromatic side-chains and aromatic ring(s) of the inhibitors are responsible for the tight binding of these varied inhibitors.

  4. Experimental Anti-Inflammatory Drug Semapimod Inhibits TLR Signaling by Targeting the TLR Chaperone gp96.

    PubMed

    Wang, Jin; Grishin, Anatoly V; Ford, Henri R

    2016-06-15

    Semapimod, a tetravalent guanylhydrazone, suppresses inflammatory cytokine production and has potential in a variety of inflammatory and autoimmune disorders. The mechanism of action of Semapimod is not well understood. In this study, we demonstrate that in rat IEC-6 intestinal epithelioid cells, Semapimod inhibits activation of p38 MAPK and NF-κB and induction of cyclooxygenase-2 by TLR ligands, but not by IL-1β or stresses. Semapimod inhibits TLR4 signaling (IC50 ≈0.3 μmol) and acts by desensitizing cells to LPS; it fails to block responses to LPS concentrations of ≥5 μg/ml. Inhibition of TLR signaling by Semapimod is almost instantaneous: the drug is effective when applied simultaneously with LPS. Semapimod blocks cell-surface recruitment of the MyD88 adapter, one of the earliest events in TLR signaling. gp96, the endoplasmic reticulum-localized chaperone of the HSP90 family critically involved in the biogenesis of TLRs, was identified as a target of Semapimod using ATP-desthiobiotin pulldown and mass spectroscopy. Semapimod inhibits ATP-binding and ATPase activities of gp96 in vitro (IC50 ≈0.2-0.4 μmol). On prolonged exposure, Semapimod causes accumulation of TLR4 and TLR9 in perinuclear space, consistent with endoplasmic reticulum retention, an anticipated consequence of impaired gp96 chaperone function. Our data indicate that Semapimod desensitizes TLR signaling via its effect on the TLR chaperone gp96. Fast inhibition by Semapimod is consistent with gp96 participating in high-affinity sensing of TLR ligands in addition to its role as a TLR chaperone. PMID:27194788

  5. Polymer-drug conjugates for intracellar molecule-targeted photoinduced inactivation of protein and growth inhibition of cancer cells

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Yuan, Huanxiang; Zhu, Chunlei; Yang, Qiong; Lv, Fengting; Liu, Libing; Wang, Shu

    2012-10-01

    For most molecule-targeted anticancer systems, intracellular protein targets are very difficult to be accessed by antibodies, and also most efforts are made to inhibit protein activity temporarily rather than inactivate them permanently. In this work we firstly designed and synthesized multifunctional polymer-drug conjugates (polythiophene-tamoxifen) for intracellular molecule-targeted binding and inactivation of protein (estrogen receptor α, ERα) for growth inhibition of MCF-7 cancer cells. Small molecule drug was conjugated to polymer side chain for intracellular signal protein targeting, and simultaneously the fluorescent characteristic of polymer for tracing the cellular uptake and localization of polythiophene-drug conjugates by cell imaging. Under light irradiation, the conjugated polymer can sensitize oxygen to produce reactive oxygen species (ROS) that specifically inactivate the targeted protein, and thus inhibit the growth of tumor cells. The conjugates showed selective growth inhibition of ERα positive cancer cells, which exhibits low side effect for our intracellular molecule-targeted therapy system.

  6. Drug Repurposing Screening Identifies Novel Compounds That Effectively Inhibit Toxoplasma gondii Growth

    PubMed Central

    Dittmar, Ashley J.; Drozda, Allison A.

    2016-01-01

    ABSTRACT The urgent need to develop new antimicrobial therapies has spawned the development of repurposing screens in which well-studied drugs and other types of compounds are tested for potential off-label uses. As a proof-of-principle screen to identify compounds effective against Toxoplasma gondii, we screened a collection of 1,120 compounds for the ability to significantly reduce Toxoplasma replication. A total of 94 compounds blocked parasite replication with 50% inhibitory concentrations of <5 µM. A significant number of these compounds are established inhibitors of dopamine or estrogen signaling. Follow-up experiments with the dopamine receptor inhibitor pimozide revealed that the drug impacted both parasite invasion and replication but did so independently of inhibition of dopamine or other neurotransmitter receptor signaling. Tamoxifen, which is an established inhibitor of the estrogen receptor, also reduced parasite invasion and replication. Even though Toxoplasma can activate the estrogen receptor, tamoxifen inhibits parasite growth independently of this transcription factor. Tamoxifen is also a potent inducer of autophagy, and we find that the drug stimulates recruitment of the autophagy marker light chain 3-green fluorescent protein onto the membrane of the vacuolar compartment in which the parasite resides and replicates. In contrast to other antiparasitic drugs, including pimozide, tamoxifen treatment of infected cells leads to a time-dependent elimination of intracellular parasites. Taken together, these data suggest that tamoxifen restricts Toxoplasma growth by inducing xenophagy or autophagic destruction of this obligate intracellular parasite. IMPORTANCE There is an urgent need to develop new therapies to treat microbial infections, and the repurposing of well-characterized compounds is emerging as one approach to achieving this goal. Using the protozoan parasite Toxoplasma gondii, we screened a library of 1,120 compounds and identified several

  7. Drug Repurposing Screening Identifies Novel Compounds That Effectively Inhibit Toxoplasma gondii Growth.

    PubMed

    Dittmar, Ashley J; Drozda, Allison A; Blader, Ira J

    2016-01-01

    The urgent need to develop new antimicrobial therapies has spawned the development of repurposing screens in which well-studied drugs and other types of compounds are tested for potential off-label uses. As a proof-of-principle screen to identify compounds effective against Toxoplasma gondii, we screened a collection of 1,120 compounds for the ability to significantly reduce Toxoplasma replication. A total of 94 compounds blocked parasite replication with 50% inhibitory concentrations of <5 µM. A significant number of these compounds are established inhibitors of dopamine or estrogen signaling. Follow-up experiments with the dopamine receptor inhibitor pimozide revealed that the drug impacted both parasite invasion and replication but did so independently of inhibition of dopamine or other neurotransmitter receptor signaling. Tamoxifen, which is an established inhibitor of the estrogen receptor, also reduced parasite invasion and replication. Even though Toxoplasma can activate the estrogen receptor, tamoxifen inhibits parasite growth independently of this transcription factor. Tamoxifen is also a potent inducer of autophagy, and we find that the drug stimulates recruitment of the autophagy marker light chain 3-green fluorescent protein onto the membrane of the vacuolar compartment in which the parasite resides and replicates. In contrast to other antiparasitic drugs, including pimozide, tamoxifen treatment of infected cells leads to a time-dependent elimination of intracellular parasites. Taken together, these data suggest that tamoxifen restricts Toxoplasma growth by inducing xenophagy or autophagic destruction of this obligate intracellular parasite. IMPORTANCE There is an urgent need to develop new therapies to treat microbial infections, and the repurposing of well-characterized compounds is emerging as one approach to achieving this goal. Using the protozoan parasite Toxoplasma gondii, we screened a library of 1,120 compounds and identified several

  8. Molecular Basis for Cyclooxygenase Inhibition by the Non-steroidal Anti-inflammatory Drug Naproxen

    SciTech Connect

    Duggan, Kelsey C.; Walters, Matthew J.; Musee, Joel; Harp, Joel M.; Kiefer, James R.; Oates, John A.; Marnett, Lawrence J.

    2010-11-15

    Naproxen ((S)-6-methoxy-{alpha}-methyl-2-naphthaleneacetic acid) is a powerful non-selective non-steroidal anti-inflammatory drug that is extensively used as a prescription and over-the-counter medication. Naproxen exhibits gastrointestinal toxicity, but its cardiovascular toxicity may be reduced compared with other drugs in its class. Despite the fact that naproxen has been marketed for many years, the molecular basis of its interaction with cyclooxygenase (COX) enzymes is unknown. We performed a detailed study of naproxen-COX-2 interactions using site-directed mutagenesis, structure-activity analysis, and x-ray crystallography. The results indicate that each of the pendant groups of the naphthyl scaffold are essential for COX inhibition, and only minimal substitutions are tolerated. Mutation of Trp-387 to Phe significantly reduced inhibition by naproxen, a result that appears unique to this inhibitor. Substitution of S or CH2 for the O atom of the p-methoxy group yielded analogs that were not affected by the W387F substitution and that exhibited increased COX-2 selectivity relative to naproxen. Crystallization and x-ray analysis yielded structures of COX-2 complexed to naproxen and its methylthio analog at 1.7 and 2.3 {angstrom} resolution, respectively. The combination of mutagenesis, structure analysis, and x-ray crystallography provided comprehensive information on the unique interactions responsible for naproxen binding to COX-2.

  9. Additive inhibition of human α1β2γ2 GABAA receptors by mixtures of commonly used drugs of abuse.

    PubMed

    Hondebrink, Laura; Tan, Sijie; Hermans, Elise; van Kleef, Regina G D M; Meulenbelt, Jan; Westerink, Remco H S

    2013-03-01

    Yearly, exposure to drugs of abuse results in ∼1 million emergency department visits in the US. In ∼50% of the visits, stimulant drugs like cocaine and amphetamine-like substances (e.g. 3,4-methylenedioxymethamphetamine (MDMA, the main active ingredient of ecstasy)) are involved, whereas in ∼60% multiple drugs are involved. These drugs induce higher dopamine and serotonin levels resulting in drug-induced toxicity. Since GABA receptors (GABA-R) provide the main inhibitory input on dopaminergic and serotonergic neurons, drug-induced inhibition of GABA-R could contribute to higher neurotransmitter levels and thus toxicity. We therefore investigated the effects of combinations of commonly abused stimulant drugs (cocaine, MDMA, 3,4-methylenedioxyamphetamine (MDA) and meta-chlorophenylpiperazine (mCPP)) on the function of the human α1β2γ2 GABAA receptor (hGABAA-R), expressed in Xenopus oocytes, using the two-electrode voltage-clamp technique. These drugs concentration-dependently inhibited the GABA-evoked current (mCPP>cocaine>MDMA>MDA). Most drug combinations decreased the GABA-evoked current stronger than the single drug. Additivity was observed during combined exposure to low concentrations of cocaine and mCPP as well as during combined exposure to MDA with cocaine or mCPP. However, combinations containing MDMA mainly resulted in sub-additivity or no additivity. At drug concentrations relevant for clinical toxicology, co-exposure to ≥2 drugs can decrease the GABA-evoked current in an additive manner. Thus, in patients exposed to multiple drugs, inhibitory GABA-ergic input is reduced more prominently, likely resulting in higher brain dopamine levels. As this will increase the risk for drug-induced toxicity, treatment of drug-intoxicated patients with drugs that enhance GABA-ergic input should be further optimized. PMID:23266428

  10. Reversal of efflux of an anticancer drug in human drug-resistant breast cancer cells by inhibition of protein kinase Cα (PKCα) activity.

    PubMed

    Kim, Chan Woo; Asai, Daisuke; Kang, Jeong-Hun; Kishimura, Akihiro; Mori, Takeshi; Katayama, Yoshiki

    2016-02-01

    P-glycoprotein (Pgp) is a 170-kDa transmembrane protein that mediates the efflux of anticancer drugs from cells. Pgp overexpression has a distinct role in cells exhibiting multidrug resistance (MDR). We examined reversal of drug resistance in human MDR breast cancer cells by inhibition of protein kinase Cα (PKCα) activity, which is associated with Pgp-mediated efflux of anticancer drugs. PKCα activity was confirmed by measurement of phosphorylation levels of a PKCα-specific peptide substrate (FKKQGSFAKKK-NH2), showing relatively higher basal activity in drug-resistant MCF-7/ADR cells (84 %) than that in drug-sensitive MCF-7 cells (63 %). PKCα activity was effectively suppressed by the PKC inhibitor, Ro-31-7549, and reversal of intracellular accumulation of doxorubicin was observed by inhibition of PKCα activity in MCF-7/ADR cells compared with their intrinsic drug resistance. Importantly, increased accumulation of doxorubicin could enhance the therapeutic efficacy of doxorubicin in MDR cells significantly. These results suggest a potential for overcoming MDR via inhibition of PKCα activity with conventional anticancer drugs. PMID:26323260

  11. Interleukin-1β biosynthesis inhibition reduces acute seizures and drug resistant chronic epileptic activity in mice.

    PubMed

    Maroso, Mattia; Balosso, Silvia; Ravizza, Teresa; Iori, Valentina; Wright, Christopher Ian; French, Jacqueline; Vezzani, Annamaria

    2011-04-01

    Experimental evidence and clinical observations indicate that brain inflammation is an important factor in epilepsy. In particular, induction of interleukin-converting enzyme (ICE)/caspase-1 and activation of interleukin (IL)-1β/IL-1 receptor type 1 axis both occur in human epilepsy, and contribute to experimentally induced acute seizures. In this study, the anticonvulsant activity of VX-765 (a selective ICE/caspase-1 inhibitor) was examined in a mouse model of chronic epilepsy with spontaneous recurrent epileptic activity refractory to some common anticonvulsant drugs. Moreover, the effects of this drug were studied in one acute model of seizures in mice, previously shown to involve activation of ICE/caspase-1. Quantitative analysis of electroencephalogram activity was done in mice exposed to acute seizures or those developing chronic epileptic activity after status epilepticus to assess the anticonvulsant effects of systemic administration of VX-765. Histological and immunohistochemical analysis of brain tissue was carried out at the end of pharmacological experiments in epileptic mice to evaluate neuropathology, glia activation and IL-1β expression, and the effect of treatment. Repeated systemic administration of VX-765 significantly reduced chronic epileptic activity in mice in a dose-dependent fashion (12.5-200 mg/kg). This effect was observed at doses ≥ 50 mg/kg, and was reversible with discontinuation of the drug. Maximal drug effect was associated with inhibition of IL-1β synthesis in activated astrocytes. The same dose regimen of VX-765 also reduced acute seizures in mice and delayed their onset time. These results support a new target system for anticonvulsant pharmacological intervention to control epileptic activity that does not respond to some common anticonvulsant drugs. PMID:21431948

  12. Drugs Which Inhibit Osteoclast Function Suppress Tumor Growth through Calcium Reduction in Bone

    PubMed Central

    Li, Xin; Liao, Jinhui; Park, Serk In; Koh, Amy J; Sadler, William D; Pienta, Kenneth J; Rosol, Thomas J; McCauley, Laurie K

    2011-01-01

    Prostate carcinoma frequently metastasizes to bone where the microenvironment facilitates its growth. Inhibition of bone resorption is effective in reducing tumor burden and bone destruction in prostate cancer. However, whether drugs that inhibit osteoclast function inhibit tumor growth independent of inhibition of bone resorption is unclear. Calcium is released during bone resorption and the calcium sensing receptor is an important regulator of cancer cell proliferation. The goal of this investigation was to elucidate the role of calcium released during bone resorption and to determine the impact of drugs which suppress bone resorption on tumor growth in bone. To compare tumor growth in a skeletal versus non-skeletal site, equal numbers of canine prostate cancer cells expressing luciferase (ACE-1luc) prostate cancer cells were inoculated into a simple collagen matrix, neonatal mouse vertebrae (vossicles), human de-proteinized bone, or a mineralized collagen matrix. Implants were placed subcutaneously into athymic mice. Luciferase activity was used to track tumor growth weekly and at one month tumors were dissected for histologic analysis. Luciferase activity and tumor size were greater in vossicles, de-proteinized bone and mineralized collagen matrix versus non-mineralized collagen implants. The human osteoblastic prostate carcinoma cell line C4-2b also grew better in a mineral rich environment with a greater proliferation of C4-2b cells reflected by Ki-67 staining. Zoledronic acid (ZA), a bisphosphonate, and recombinant OPG-Fc, a RANKL inhibitor, were administered to mice bearing vertebral implants (vossicles) containing ACE-1 osteoblastic prostate cancer cells. Vossicles or collagen matrices were seeded with ACE-1luc cells subcutaneously in athymic mice (2 vossicles, 2 collagen implants/mouse). Mice received ZA (5μg/mouse, twice/week), (OPG-Fc at 10mg/kg, 3 times/week) or vehicle, and luciferase activity was measured weekly. Histologic analysis of the tumors

  13. Effect of dicycloplatin, a novel platinum chemotherapeutical drug, on inhibiting cell growth and inducing cell apoptosis.

    PubMed

    Li, Guang-quan; Chen, Xing-gui; Wu, Xing-ping; Xie, Jing-dun; Liang, Yong-ju; Zhao, Xiao-qin; Chen, Wei-qiang; Fu, Li-wu

    2012-01-01

    Dicycloplatin, a new supramolecular platinum-based antitumor drug, has been approved by the State Food and Administration (SFDA) of China. In this study, we investigated the anticancer activity of dicycloplatin in cancer cells and signaling pathways involved in dicycloplatin-induced apoptosis. Dicycloplatin inhibited the proliferation of cancer cells and increased the percentage of apoptosis in a concentration-dependent manner. Besides, some apoptosis related events were observed after treatment with dicycloplatin, including increase of reactive oxygen species (ROS), collapse of mitochondrial membrane potential (Δψm), release of cytochrome c from the mitochondria to the cytosol, upregulation of p53, which were accompanied by activation of caspase-9, caspase-3, caspase-8, and poly (ADP-ribose) polymerase cleavage in a concentration-dependent manner. The role of apoptosis in dicycloplatin-mediated cell death was further confirmed by the concomitant treatment with caspase-8 or caspase-9 inhibitors, which inhibited apoptosis and PARP cleavage. Intracellular glutathione (GSH) was also found to inhibit the cytotoxic effect of dicycloplatin. In conclusion, these findings suggest that dicycloplatin induces apoptosis through ROS stress-mediated death receptor pathway and mitochondrial pathway which is similar to carboplatin. PMID:23152837

  14. Inhibition mechanism exploration of investigational drug TAK-441 as inhibitor against Vismodegib-resistant Smoothened mutant.

    PubMed

    Ishii, Tsuyoshi; Shimizu, Yuji; Nakashima, Kosuke; Kondo, Shigeru; Ogawa, Kazumasa; Sasaki, Satoshi; Matsui, Hideki

    2014-01-15

    Hedgehog signaling is a driving force in medulloblastoma and basal cell carcinoma (BCC), making it an attractive therapeutic target. Vismodegib recently received FDA approval for the treatment of inoperable BCC, but a drug-resistant Smoothened (Smo) mutant (D473H) was identified in a clinical study. TAK-441 is a pyrrolo[3,2-c]pyridine-4-one derivative that potently inhibits Hh signal transduction and is currently under investigation in clinical trials. We demonstrated that TAK-441 inhibits reporter activity in D473H-transfected cells with an IC50 of 79nM, while Vismodegib showed an IC50=7100nM. In order to investigate the mode of inhibition, we evaluated the Smo inhibitors with three different binding assays, such as [(3)H]-TAK-441 membrane binding assay, affinity selection-MS detection assay, and bodipy-cylopamine whole cell assay. In three different assays, Vismodegib and cyclopamine showed lower affinity for the D473H mutant in comparison with wild-type Smo. On the other hand, TAK-441 showed almost equal binding affinity for the D473H mutant compared with wild-type Smo in the binding assays, although TAK-441 binds to the same binding site as two other well-known inhibitors. These in vitro findings suggest that TAK-441 has the potential for clinical use in cancers that are dependent on Hedgehog signaling, including wild-type tumors and Vismodegib-resistant D473H mutants. PMID:24291104

  15. Inhibition of thioredoxin 1 leads to apoptosis in drug-resistant multiple myeloma

    PubMed Central

    Raninga, Prahlad V.; Di Trapani, Giovanna; Vuckovic, Slavica; Bhatia, Maneet; Tonissen, Kathryn F.

    2015-01-01

    Multiple myeloma (MM) is a hematological malignancy characterized by the aberrant accumulation of clonal plasma cells in the bone marrow. Despite recent advancement in anti-myeloma treatment, MM remains an incurable disease. This study showed higher intrinsic oxidative stress and higher Trx1 and TrxR1 protein levels in MM cells compared to normal cells. Drug-induced Trx1 (PX-12) and TrxR1 (Auranofin) inhibition disrupted redox homeostasis resulting in ROS-induced apoptosis in MM cells and a reduction in clonogenic activity. Knockdown of either Trx1 or TrxR1 reduced MM cell viability. Trx1 inhibition by PX-12 sensitized MM cells to undergo apoptosis in response to the NF-кβ inhibitors, BAY 11-7082 and curcumin. PX-12 treatment decreased the expression of the NF-кβ subunit p65 in MM cells. Bortezomib-resistant MM cells contained higher Trx1 protein levels compared to the parental cells and PX-12 treatment resulted in apoptosis. Thus, increased Trx1 enhances MM cell growth and survival and exerts resistance to NF-кβ inhibitors. Therefore inhibiting the thioredoxin system may be an effective therapeutic strategy to treat newly diagnosed as well as relapsed/refractory MM. PMID:25945832

  16. Inhibition of thioredoxin 1 leads to apoptosis in drug-resistant multiple myeloma.

    PubMed

    Raninga, Prahlad V; Di Trapani, Giovanna; Vuckovic, Slavica; Bhatia, Maneet; Tonissen, Kathryn F

    2015-06-20

    Multiple myeloma (MM) is a hematological malignancy characterized by the aberrant accumulation of clonal plasma cells in the bone marrow. Despite recent advancement in anti-myeloma treatment, MM remains an incurable disease. This study showed higher intrinsic oxidative stress and higher Trx1 and TrxR1 protein levels in MM cells compared to normal cells. Drug-induced Trx1 (PX-12) and TrxR1 (Auranofin) inhibition disrupted redox homeostasis resulting in ROS-induced apoptosis in MM cells and a reduction in clonogenic activity. Knockdown of either Trx1 or TrxR1 reduced MM cell viability. Trx1 inhibition by PX-12 sensitized MM cells to undergo apoptosis in response to the NF-κβ inhibitors, BAY 11-7082 and curcumin. PX-12 treatment decreased the expression of the NF-κβ subunit p65 in MM cells. Bortezomib-resistant MM cells contained higher Trx1 protein levels compared to the parental cells and PX-12 treatment resulted in apoptosis. Thus, increased Trx1 enhances MM cell growth and survival and exerts resistance to NF-κβ inhibitors. Therefore inhibiting the thioredoxin system may be an effective therapeutic strategy to treat newly diagnosed as well as relapsed/refractory MM. PMID:25945832

  17. Identification of synthetic lethality of PLK1 inhibition and microtubule-destabilizing drugs.

    PubMed

    Hugle, M; Belz, K; Fulda, S

    2015-12-01

    Polo-like kinase 1 (PLK1) is frequently overexpressed in cancer, which correlates with poor prognosis. Therefore, we investigated PLK1 as therapeutic target using rhabdomyosarcoma (RMS) as a model. Here, we identify a novel synthetic lethal interaction of PLK1 inhibitors and microtubule-destabilizing drugs in preclinical RMS models and elucidate the underlying molecular mechanisms of this synergism. PLK1 inhibitors (i.e., BI 2536 and BI 6727) synergistically induce apoptosis together with microtubule-destabilizing drugs (i.e., vincristine (VCR), vinblastine (VBL) and vinorelbine (VNR)) in several RMS cell lines (combination index <0.9) including a patient-derived primary RMS culture. Importantly, PLK1 inhibitors and VCR cooperate to significantly suppress RMS growth in two in vivo models, including a mouse xenograft model, without causing additive toxicity. In addition, no toxicity was observed in non-malignant fibroblast or myoblast cultures. Mechanistically, BI 2536/VCR co-treatment triggers mitotic arrest, which initiates mitochondrial apoptosis by inactivation of antiapoptotic BCL-2 family proteins, followed by BAX/BAK activation, production of reactive oxygen species (ROS) and activation of caspase-dependent or caspase-independent effector pathways. This conclusion is supported by data showing that BI 2536/VCR-induced apoptosis is significantly inhibited by preventing cells to enter mitosis, by overexpression of BCL-2 or a non-degradable MCL-1 mutant, by BAK knockdown, ROS scavengers, caspase inhibition or endonuclease G silencing. This identification of a novel synthetic lethality of PLK1 inhibitors and microtubule-destabilizing drugs has important implications for developing PLK1 inhibitor-based combination treatments. PMID:26024389

  18. Identification of approved and investigational drugs that inhibit hypoxia-inducible factor-1 signaling

    PubMed Central

    Hsu, Chia-Wen; Huang, Ruili; Khuc, Thai; Shou, David; Bullock, Joshua; Grooby, Suzanne; Griffin, Sue; Zou, Chaozhong; Little, Annette; Astley, Holly; Xia, Menghang

    2016-01-01

    One of the requirements for tumor development is blood supply, most often driven by hypoxia-induced angiogenesis. Hypoxia induces the stabilization of hypoxia-inducible factor-1 alpha (HIF-1α), which induces expression of an angiogenic factor, vascular endothelial growth factor (VEGF). The purpose of this study is to validate a new screening platform combined with orthogonal assays to rapidly identify HIF-1 inhibitors and to evaluate the effectiveness of approved drugs on modulating HIF-1 signaling. We generated an endogenous HIF-1α–NanoLuc luciferase reporter allele in the human HCT116 colon cancer cell line using genome editing and screened a panel of small interfering RNAs (siRNAs) to 960 druggable targets and approximately 2,500 drugs on a quantitative high-throughput screening (qHTS) platform. Selected compounds were further investigated with secondary assays to confirm their anti-HIF activity and to study their mode of action. The qHTS assay identified over 300 drugs that inhibited HIF-1α-NanoLuc expression. The siRNA screening results supported the effectiveness of several target-specific inhibitors. Moreover, the identified HIF-1 inhibitors, such as mycophenolate mofetil, niclosamide, and trametinib, were able to suppress cancer cell proliferation and angiogenesis. Our study indicates that blocking the mitogen-activated protein kinase (MAPK) and phosphoinositol 3-kinase (PI3K) pathways effectively inhibits hypoxia-induced HIF-1α accumulation and HIF-1α transactivation and that proteasome inhibitors induce accumulation and decrease transcriptional activity of HIF-1α. These findings underline the importance of developing a battery of robust assay platforms and confirmation studies that focus on endogenous protein targets so that only relevant and reliable data will be taken into pre-clinical and clinical studies. PMID:26882567

  19. Inhibition of the enzyme, GABA-aminotransferase in human platelets by vigabatrin, a potential antiepileptic drug.

    PubMed Central

    Rimmer, E; Kongola, G; Richens, A

    1988-01-01

    1. The effect of the new antiepileptic drug, vigabatrin (gamma-vinyl GABA), on the platelet enzyme, GABA-aminotransferase (GABA-T) was investigated in volunteers and patients. Platelets GABA-T activity was assayed using a radioenzymic method. 2. Three single oral doses of vigabatrin (1 g, 2 g and 4 g) were given to six healthy male volunteers in an open randomised cross over study and compared with a baseline period preceding the three treatments. 3. Significant inhibition of the platelet GABA-T was produced by treatment with all three doses and a dose-response relationship was demonstrated. The minimum enzyme activities after 1 g, 2 g and 4 g doses were 43%, 30% and 21% respectively compared with the control values. 4. A significant depression of enzyme activity occurred at 30 min after drug administration and the values remained below control values for 72 h post-dose, outlasting the presence of the drug itself in the plasma. 5. Eight patients with chronic refractory epilepsy were treated with vigabatrin for 6 weeks. After taking the 2 g daily dose for 1 week there was a marked reduction in platelet enzyme activity in all subjects but the enzyme inhibition produced by the 3 g dose was not significantly different from that produced by the 2 g dose, even after 4 weeks treatment with the larger dose. The mean enzyme activity was approximately 30% throughout the active treatment period. One week after stopping vigabatrin, the enzyme levels were not significantly different from the baseline values.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3358887

  20. Identification of approved and investigational drugs that inhibit hypoxia-inducible factor-1 signaling.

    PubMed

    Hsu, Chia-Wen; Huang, Ruili; Khuc, Thai; Shou, David; Bullock, Joshua; Grooby, Suzanne; Griffin, Sue; Zou, Chaozhong; Little, Annette; Astley, Holly; Xia, Menghang

    2016-02-16

    One of the requirements for tumor development is blood supply, most often driven by hypoxia-induced angiogenesis. Hypoxia induces the stabilization of hypoxia-inducible factor-1 alpha (HIF-1α), which induces expression of an angiogenic factor, vascular endothelial growth factor (VEGF). The purpose of this study is to validate a new screening platform combined with orthogonal assays to rapidly identify HIF-1 inhibitors and to evaluate the effectiveness of approved drugs on modulating HIF-1 signaling. We generated an endogenous HIF-1α-NanoLuc luciferase reporter allele in the human HCT116 colon cancer cell line using genome editing and screened a panel of small interfering RNAs (siRNAs) to 960 druggable targets and approximately 2,500 drugs on a quantitative high-throughput screening (qHTS) platform. Selected compounds were further investigated with secondary assays to confirm their anti-HIF activity and to study their mode of action. The qHTS assay identified over 300 drugs that inhibited HIF-1α-NanoLuc expression. The siRNA screening results supported the effectiveness of several target-specific inhibitors. Moreover, the identified HIF-1 inhibitors, such as mycophenolate mofetil, niclosamide, and trametinib, were able to suppress cancer cell proliferation and angiogenesis. Our study indicates that blocking the mitogen-activated protein kinase (MAPK) and phosphoinositol 3-kinase (PI3K) pathways effectively inhibits hypoxia-induced HIF-1α accumulation and HIF-1α transactivation and that proteasome inhibitors induce accumulation and decrease transcriptional activity of HIF-1α. These findings underline the importance of developing a battery of robust assay platforms and confirmation studies that focus on endogenous protein targets so that only relevant and reliable data will be taken into pre-clinical and clinical studies. PMID:26882567

  1. Challenges for drug discovery - a case study of urokinase receptor inhibition

    PubMed Central

    Chen, Zhuo; Lin, Lin; Huai, Qing; Huang, Mingdong

    2009-01-01

    Urokinase receptor (uPAR) is a widely recognized target for potential treatment of cancer. The development of uPAR inhibitors has been going on for over a decade. Despite the identification and validation of many highly potent hits using screening or medicinal approaches, none of them has been moved further along the drug discovery pipeline. The development of uPAR inhibitors exemplifies several challenges now faced by drug discovery. These include 1) hydrophobicity and thus poor bioavailability of the inhibitors from screening approaches; 2) specificity of the inhibitor, where a peptidyl inhibitor causes conformational change of the receptor; 3) species specificity, where some inhibitors developed based on the human receptor do not inhibit the murine receptor and thus cannot be validated in mouse models. The recently determined crystal structures of uPAR in complex with its ligand or inhibitor not only provide the structural insight to understand these challenges but also offer a potential solution for further inhibitor development and thus illustrate the importance of structural information in facilitating drug discovery. PMID:20025562

  2. Evolution of mutualism between species

    SciTech Connect

    Post, W.M.; Travis, C.C.; DeAngelis, D.L.

    1980-01-01

    Recent theoretical work on mutualism, the interaction between species populations that is mutually beneficial, is reviewed. Several ecological facts that should be addressed in the construction of dynamic models for mutualism are examined. Basic terminology is clarified. (PSB)

  3. Exploring BSEP inhibition-mediated toxicity with a mechanistic model of drug-induced liver injury

    PubMed Central

    Woodhead, Jeffrey L.; Yang, Kyunghee; Siler, Scott Q.; Watkins, Paul B.; Brouwer, Kim L. R.; Barton, Hugh A.; Howell, Brett A.

    2014-01-01

    Inhibition of the bile salt export pump (BSEP) has been linked to incidence of drug-induced liver injury (DILI), presumably by the accumulation of toxic bile acids in the liver. We have previously constructed and validated a model of bile acid disposition within DILIsym®, a mechanistic model of DILI. In this paper, we use DILIsym® to simulate the DILI response of the hepatotoxic BSEP inhibitors bosentan and CP-724,714 and the non-hepatotoxic BSEP inhibitor telmisartan in humans in order to explore whether we can predict that hepatotoxic BSEP inhibitors can cause bile acid accumulation to reach toxic levels. We also simulate bosentan in rats in order to illuminate potential reasons behind the lack of toxicity in rats compared to the toxicity observed in humans. DILIsym® predicts that bosentan, but not telmisartan, will cause mild hepatocellular ATP decline and serum ALT elevation in a simulated population of humans. The difference in hepatotoxic potential between bosentan and telmisartan is consistent with clinical observations. However, DILIsym® underpredicts the incidence of bosentan toxicity. DILIsym® also predicts that bosentan will not cause toxicity in a simulated population of rats, and that the difference between the response to bosentan in rats and in humans is primarily due to the less toxic bile acid pool in rats. Our simulations also suggest a potential synergistic role for bile acid accumulation and mitochondrial electron transport chain (ETC) inhibition in producing the observed toxicity in CP-724,714, and suggest that CP-724,714 metabolites may also play a role in the observed toxicity. Our work also compares the impact of competitive and noncompetitive BSEP inhibition for CP-724,714 and demonstrates that noncompetitive inhibition leads to much greater bile acid accumulation and potential toxicity. Our research demonstrates the potential for mechanistic modeling to contribute to the understanding of how bile acid transport inhibitors cause DILI

  4. Behavioral Ecology: Manipulative Mutualism.

    PubMed

    Hughes, David P

    2015-09-21

    A new study reveals that an apparent mutualism between lycaenid caterpillars and their attendant ants may not be all it seems, as the caterpillars produce secretions that modify the brains and behavior of their attendant ants. PMID:26394105

  5. Prediction of CYP2D6 drug interactions from in vitro data: evidence for substrate-dependent inhibition.

    PubMed

    VandenBrink, Brooke M; Foti, Robert S; Rock, Dan A; Wienkers, Larry C; Wahlstrom, Jan L

    2012-01-01

    Predicting the magnitude of potential drug-drug interactions is important for underwriting patient safety in the clinical setting. Substrate-dependent inhibition of cytochrome P450 enzymes may confound extrapolation of in vitro results to the in vivo situation. However, the potential for substrate-dependent inhibition with CYP2D6 has not been well characterized. The inhibition profiles of 20 known inhibitors of CYP2D6 were characterized in vitro against four clinically relevant CYP2D6 substrates (desipramine, dextromethorphan, metoprolol, and thioridazine) and bufuralol. Dextromethorphan exhibited the highest sensitivity to in vitro inhibition, whereas metoprolol was the least sensitive. In addition, when metoprolol was the substrate, inhibitors with structurally constrained amino moieties (clozapine, debrisoquine, harmine, quinidine, and yohimbine) exhibited at least a 5-fold decrease in inhibition potency when results were compared with those for dextromethorphan. Atypical inhibition kinetics were observed for these and other inhibitor-substrate pairings. In silico docking studies suggested that interactions with Glu216 and an adjacent hydrophobic binding pocket may influence substrate sensitivity and inhibition potency for CYP2D6. The in vivo sensitivities of the clinically relevant CYP2D6 substrates desipramine, dextromethorphan, and metoprolol were determined on the basis of literature drug-drug interaction (DDI) outcomes. Similar to the in vitro results, dextromethorphan exhibited the highest sensitivity to CYP2D6 inhibition in vivo. Finally, the magnitude of in vivo CYP2D6 DDIs caused by quinidine was predicted using desipramine, dextromethorphan, and metoprolol. Comparisons of the predictions with literature results indicated that the marked decrease in inhibition potency observed for the metoprolol-quinidine interaction in vitro translated to the in vivo situation. PMID:21976621

  6. Altiratinib Inhibits Tumor Growth, Invasion, Angiogenesis, and Microenvironment-Mediated Drug Resistance via Balanced Inhibition of MET, TIE2, and VEGFR2.

    PubMed

    Smith, Bryan D; Kaufman, Michael D; Leary, Cynthia B; Turner, Benjamin A; Wise, Scott C; Ahn, Yu Mi; Booth, R John; Caldwell, Timothy M; Ensinger, Carol L; Hood, Molly M; Lu, Wei-Ping; Patt, Tristan W; Patt, William C; Rutkoski, Thomas J; Samarakoon, Thiwanka; Telikepalli, Hanumaiah; Vogeti, Lakshminarayana; Vogeti, Subha; Yates, Karen M; Chun, Lawrence; Stewart, Lance J; Clare, Michael; Flynn, Daniel L

    2015-09-01

    Altiratinib (DCC-2701) was designed based on the rationale of engineering a single therapeutic agent able to address multiple hallmarks of cancer (1). Specifically, altiratinib inhibits not only mechanisms of tumor initiation and progression, but also drug resistance mechanisms in the tumor and microenvironment through balanced inhibition of MET, TIE2 (TEK), and VEGFR2 (KDR) kinases. This profile was achieved by optimizing binding into the switch control pocket of all three kinases, inducing type II inactive conformations. Altiratinib durably inhibits MET, both wild-type and mutated forms, in vitro and in vivo. Through its balanced inhibitory potency versus MET, TIE2, and VEGFR2, altiratinib provides an agent that inhibits three major evasive (re)vascularization and resistance pathways (HGF, ANG, and VEGF) and blocks tumor invasion and metastasis. Altiratinib exhibits properties amenable to oral administration and exhibits substantial blood-brain barrier penetration, an attribute of significance for eventual treatment of brain cancers and brain metastases. PMID:26285778

  7. Inhibition of bile canalicular network formation in rat sandwich cultured hepatocytes by drugs associated with risk of severe liver injury.

    PubMed

    Takemura, Akinori; Izaki, Aya; Sekine, Shuichi; Ito, Kousei

    2016-09-01

    Idiosyncratic drug-induced liver injury is a clinical concern with serious consequences. Although many preclinical screening methods have been proposed, it remains difficult to identify compounds associated with this rare but potentially fatal liver condition. Here, we propose a novel assay system to assess the risk of liver injury. Rat primary hepatocytes were cultured in a sandwich configuration, which enables the formation of a typical bile canalicular network. From day 2 to 3, test drugs, mostly selected from a list of cholestatic drugs, were administered, and the length of the network was semi-quantitatively measured by immunofluorescence. Liver injury risk information was collected from drug labels and was compared with in vitro measurements. Of 23 test drugs examined, 15 exhibited potent inhibition of bile canalicular network formation (<60% of control). Effects on cell viability were negligible or minimal as confirmed by lactate dehydrogenase leakage and cellular ATP content assays. For the potent 15 drugs, IC50 values were determined. Finally, maximum daily dose divided by the inhibition constant gave good separation of the highest risk of severe liver toxicity drugs such as troglitazone, benzbromarone, flutamide, and amiodarone from lower risk drugs. In conclusion, inhibitory effect on the bile canalicular network formation observed in in vitro sandwich cultured hepatocytes evaluates a new aspect of drug toxicity, particularly associated with aggravation of liver injury. PMID:27256767

  8. Common Drugs Inhibit Human Organic Cation Transporter 1 (OCT1)-Mediated Neurotransmitter Uptake

    PubMed Central

    Boxberger, Kelli H.; Hagenbuch, Bruno

    2014-01-01

    The human organic cation transporter 1 (OCT1) is a polyspecific transporter involved in the uptake of positively charged and neutral small molecules in the liver. To date, few endogenous compounds have been identified as OCT1 substrates; more importantly, the effect of drugs on endogenous substrate transport has not been examined. In this study, we established monoamine neurotransmitters as substrates for OCT1, specifically characterizing serotonin transport in human embryonic kidney 293 cells. Kinetic analysis yielded a Km of 197 micomolar and a Vmax of 561 pmol/mg protein/minute for serotonin. Furthermore, we demonstrated that serotonin uptake was inhibited by diphenhydramine, fluoxetine, imatinib, and verapamil, with IC50 values in the low micromolar range. These results were recapitulated in primary human hepatocytes, suggesting that OCT1 plays a significant role in hepatic elimination of serotonin and that xenobiotics may alter the elimination of endogenous compounds as a result of interactions at the transporter level. PMID:24688079

  9. Capsaicin Enhances the Drug Sensitivity of Cholangiocarcinoma through the Inhibition of Chemotherapeutic-Induced Autophagy

    PubMed Central

    Hong, Zai-Fa; Zhao, Wen-Xiu; Yin, Zhen-Yu; Xie, Cheng-Rong; Xu, Ya-Ping; Chi, Xiao-Qin; Zhang, Sheng; Wang, Xiao-Min

    2015-01-01

    Cholangiocarcinoma (CCA), a devastating cancer with a poor prognosis, is resistant to the currently available chemotherapeutic agents. Capsaicin, the major pungent ingredient found in hot red chili peppers of the genus Capsicum, suppresses the growth of several malignant cell lines. Our aims were to investigate the role and mechanism of capsaicin with respect to the sensitivity of CCA cells to chemotherapeutic agents. The effect of capsaicin on CCA tumor sensitivity to 5-fluorouracil (5-FU) was assessed in vitro in CCA cells and in vivo in a xenograft model. The drug sensitivity of QBC939 to 5-FU was significantly enhanced by capsaicin compared with either agent alone. In addition, the combination of capsaicin with 5-FU was synergistic, with a combination index (CI) < 1, and the combined treatment also suppressed tumor growth in the CCA xenograft to a greater extent than 5-FU alone. Further investigation revealed that the autophagy induced by 5-FU was inhibited by capsaicin. Moreover, the decrease in AKT and S6 phosphorylation induced by 5-FU was effectively reversed by capsaicin, indicating that capsaicin inhibits 5-FU-induced autophagy by activating the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway in CCA cells. Taken together, these results demonstrate that capsaicin may be a useful adjunct therapy to improve chemosensitivity in CCA. This effect likely occurs via PI3K/AKT/mTOR pathway activation, suggesting a promising strategy for the development of combination drugs for CCA. PMID:25933112

  10. A thiopurine drug inhibits West Nile virus production in cell culture, but not in mice.

    PubMed

    Lim, Pei-Yin; Keating, Julie A; Hoover, Spencer; Striker, Rob; Bernard, Kristen A

    2011-01-01

    Many viruses within the Flavivirus genus cause significant disease in humans; however, effective antivirals against these viruses are not currently available. We have previously shown that a thiopurine drug, 6-methylmercaptopurine riboside (6MMPr), inhibits replication of distantly related viruses within the Flaviviridae family in cell culture, including bovine viral diarrhea virus and hepatitis C virus replicon. Here we further examined the potential antiviral effect of 6MMPr on several diverse flaviviruses. In cell culture, 6MMPr inhibited virus production of yellow fever virus, dengue virus-2 (DENV-2) and West Nile virus (WNV) in a dose-dependent manner, and DENV-2 was significantly more sensitive to 6MMPr treatment than WNV. We then explored the use of 6MMPr as an antiviral against WNV in an immunocompetent mouse model. Once a day treatment of mice with 0.5 mg 6MMPr was just below the toxic dose in our mouse model, and this dose was used in subsequent studies. Mice were treated with 6MMPr immediately after subcutaneous inoculation with WNV for eight consecutive days. Treatment with 6MMPr exacerbated weight loss in WNV-inoculated mice and did not significantly affect mortality. We hypothesized that 6MMPr has low bioavailability in the central nervous system (CNS) and examined the effect of pre-treatment with 6MMPr on viral loads in the periphery and CNS. Pre-treatment with 6MMPr had no significant effect on viremia or viral titers in the periphery, but resulted in significantly higher viral loads in the brain, suggesting that the effect of 6MMPr is tissue-dependent. In conclusion, despite being a potent inhibitor of flaviviruses in cell culture, 6MMPr was not effective against West Nile disease in mice; however, further studies are warranted to reduce the toxicity and/or improve the bioavailability of this potential antiviral drug. PMID:22039536

  11. Capsaicin Enhances the Drug Sensitivity of Cholangiocarcinoma through the Inhibition of Chemotherapeutic-Induced Autophagy.

    PubMed

    Hong, Zai-Fa; Zhao, Wen-Xiu; Yin, Zhen-Yu; Xie, Cheng-Rong; Xu, Ya-Ping; Chi, Xiao-Qin; Zhang, Sheng; Wang, Xiao-Min

    2015-01-01

    Cholangiocarcinoma (CCA), a devastating cancer with a poor prognosis, is resistant to the currently available chemotherapeutic agents. Capsaicin, the major pungent ingredient found in hot red chili peppers of the genus Capsicum, suppresses the growth of several malignant cell lines. Our aims were to investigate the role and mechanism of capsaicin with respect to the sensitivity of CCA cells to chemotherapeutic agents. The effect of capsaicin on CCA tumor sensitivity to 5-fluorouracil (5-FU) was assessed in vitro in CCA cells and in vivo in a xenograft model. The drug sensitivity of QBC939 to 5-FU was significantly enhanced by capsaicin compared with either agent alone. In addition, the combination of capsaicin with 5-FU was synergistic, with a combination index (CI) < 1, and the combined treatment also suppressed tumor growth in the CCA xenograft to a greater extent than 5-FU alone. Further investigation revealed that the autophagy induced by 5-FU was inhibited by capsaicin. Moreover, the decrease in AKT and S6 phosphorylation induced by 5-FU was effectively reversed by capsaicin, indicating that capsaicin inhibits 5-FU-induced autophagy by activating the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway in CCA cells. Taken together, these results demonstrate that capsaicin may be a useful adjunct therapy to improve chemosensitivity in CCA. This effect likely occurs via PI3K/AKT/mTOR pathway activation, suggesting a promising strategy for the development of combination drugs for CCA. PMID:25933112

  12. Classification of Drugs Based on Properties of Sodium Channel Inhibition: A Comparative Automated Patch-Clamp Study

    PubMed Central

    Lenkey, Nora; Karoly, Robert; Lukacs, Peter; Vizi, E. Sylvester; Sunesen, Morten; Fodor, Laszlo; Mike, Arpad

    2010-01-01

    Background There is only one established drug binding site on sodium channels. However, drug binding of sodium channels shows extreme promiscuity: ∼25% of investigated drugs have been found to potently inhibit sodium channels. The structural diversity of these molecules suggests that they may not share the binding site, and/or the mode of action. Our goal was to attempt classification of sodium channel inhibitors by measuring multiple properties of inhibition in electrophysiology experiments. We also aimed to investigate if different properties of inhibition correlate with specific chemical properties of the compounds. Methodology/Principal Findings A comparative electrophysiological study of 35 compounds, including classic sodium channel inhibitors (anticonvulsants, antiarrhythmics and local anesthetics), as well as antidepressants, antipsychotics and neuroprotective agents, was carried out using rNav1.2 expressing HEK-293 cells and the QPatch automatic patch-clamp instrument. In the multi-dimensional space defined by the eight properties of inhibition (resting and inactivated affinity, potency, reversibility, time constants of onset and offset, use-dependence and state-dependence), at least three distinct types of inhibition could be identified; these probably reflect distinct modes of action. The compounds were clustered similarly in the multi-dimensional space defined by relevant chemical properties, including measures of lipophilicity, aromaticity, molecular size, polarity and electric charge. Drugs of the same therapeutic indication typically belonged to the same type. We identified chemical properties, which were important in determining specific properties of inhibition. State-dependence correlated with lipophilicity, the ratio of the neutral form of molecules, and aromaticity: We noticed that the highly state dependent inhibitors had at least two aromatic rings, logP>4.0, and pKa<8.0. Conclusions/Significance The correlations of inhibition properties

  13. Anti-inflammatory drug (BW755C) inhibits airway hyperresponsiveness induced by ozone in dogs

    SciTech Connect

    Fabbri, L.M.; Aizawa, H.; O'Byrne, P.M.; Bethel, R.A.; Walters, E.H.; Holtzman, M.J.; Nadel, J.A.

    1985-08-01

    To follow up a previous observation that airway hyperresponsiveness induced by ozone is linked to airway inflammation, the authors investigated the effect of BW755C, an anti-inflammatory drug, on ozone-induced hyperresponsiveness in dogs. Airway responsiveness was assessed with dose-response curves of acetylcholine aerosol versus pulmonary resistance in two sets of experiments. In one set (placebo treatment), five dogs were given only saline solution treatment and were studied before treatment or ozone exposure and then after treatment both before and after ozone (3.0 ppm, 2 hours); in another set (BW755C treatment), the same dogs were studied before BW755C treatment or ozone and then after treatment (10 mg/kg intravenously) both before and after ozone. When the dogs were given no BW755C treatment, ozone induced a marked increase in airway responsiveness to acetylcholine. When the dogs were given BW755C, responsiveness was no different during treatment than before treatment but, more importantly, responsiveness did not increase significantly after ozone. The authors conclude that BW755C markedly inhibits ozone-induced airway hyperresponsiveness in dogs, probably by inhibiting the formation of oxygenation products of arachidonic acid.

  14. Antipsychotic Drugs Inhibit Platelet Aggregation via P2Y1 and P2Y12 Receptors

    PubMed Central

    Wu, Chang-Chieh; Tsai, Fu-Ming; Chen, Mao-Liang; Wu, Semon; Lee, Ming-Cheng; Tsai, Tzung-Chieh; Wang, Lu-Kai; Wang, Chun-Hua

    2016-01-01

    Antipsychotic drugs (APDs) used to treat clinical psychotic syndromes cause a variety of blood dyscrasias. APDs suppress the aggregation of platelets; however, the underlying mechanism remains unknown. We first analyzed platelet aggregation and clot formation in platelets treated with APDs, risperidone, clozapine, or haloperidol, using an aggregometer and rotational thromboelastometry (ROTEM). Our data indicated that platelet aggregation was inhibited, that clot formation time was increased, and that clot firmness was decreased in platelets pretreated with APDs. We also examined the role two major adenosine diphosphate (ADP) receptors, P2Y1 and P2Y12, play in ADP-mediated platelet activation and APD-mediated suppression of platelet aggregation. Our results show that P2Y1 receptor stimulation with ADP-induced calcium influx was inhibited by APDs in human and rats' platelets, as assessed by in vitro or ex vivo approach, respectively. In contrast, APDs, risperidone and clozapine, alleviated P2Y12-mediated cAMP suppression, and the release of thromboxane A2 and arachidonic acid by activated platelets decreased after APD treatment in human and rats' platelets. Our data demonstrate that each APD tested significantly suppressed platelet aggregation via different mechanisms. PMID:27069920

  15. Metabolic Drug-Drug Interaction Potential of Macrolactin A and 7-O-Succinyl Macrolactin A Assessed by Evaluating Cytochrome P450 Inhibition and Induction and UDP-Glucuronosyltransferase Inhibition In Vitro

    PubMed Central

    Bae, Soo Hyeon; Kwon, Min Jo; Park, Jung Bae; Kim, Doyun; Kim, Dong-Hee; Kang, Jae-Seon; Kim, Chun-Gyu; Oh, Euichaul

    2014-01-01

    Macrolactin A (MA) and 7-O-succinyl macrolactin A (SMA), polyene macrolides containing a 24-membered lactone ring, show antibiotic effects superior to those of teicoplanin against vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus. MA and SMA are currently being evaluated as antitumor agents in preclinical studies in Korea. We evaluated the potential of MA and SMA for the inhibition or induction of human liver cytochrome P450 (CYP) enzymes and UDP-glucuronosyltransferases (UGTs) in vitro to assess their safety as new molecular entities. We demonstrated that MA and SMA are potent competitive inhibitors of CYP2C9, with Ki values of 4.06 μM and 10.6 μM, respectively. MA and SMA also weakly inhibited UGT1A1 activity, with Ki values of 40.1 μM and 65.3 μM, respectively. However, these macrolactins showed no time-dependent inactivation of the nine CYPs studied. In addition, MA and SMA did not induce CYP1A2, CYP2B6, or CYP3A4/5. On the basis of an in vitro-in vivo extrapolation, our data strongly suggested that MA and SMA are unlikely to cause clinically significant drug-drug interactions mediated via inhibition or induction of most of the CYPs involved in drug metabolism in vivo, except for the inhibition of CYP2C9 by MA. Similarly, MA and SMA are unlikely to inhibit the activity of UGT1A1, UGT1A4, UGT1A6, UGT1A9, and UGT2B7 enzymes in vivo. Although further investigations will be required to clarify the in vivo interactions of MA with CYP2C9-targeted drugs, our findings offer a clearer understanding and prediction of drug-drug interactions for the safe use of MA and SMA in clinical practice. PMID:24890600

  16. Angiotensin inhibition enhances drug delivery and potentiates chemotherapy by decompressing tumour blood vessels

    PubMed Central

    Chauhan, Vikash P.; Martin, John D.; Liu, Hao; Lacorre, Delphine A.; Jain, Saloni R.; Kozin, Sergey V.; Stylianopoulos, Triantafyllos; Mousa, Ahmed S.; Han, Xiaoxing; Adstamongkonkul, Pichet; Popović, Zoran; Huang, Peigen; Bawendi, Moungi G.; Boucher, Yves; Jain, Rakesh K.

    2013-01-01

    Cancer and stromal cells actively exert physical forces (solid stress) to compress tumour blood vessels, thus reducing vascular perfusion. Tumour interstitial matrix also contributes to solid stress, with hyaluronan implicated as the primary matrix molecule responsible for vessel compression because of its swelling behaviour. Here we show, unexpectedly, that hyaluronan compresses vessels only in collagen-rich tumours, suggesting that collagen and hyaluronan together are critical targets for decompressing tumour vessels. We demonstrate that the angiotensin inhibitor losartan reduces stromal collagen and hyaluronan production, associated with decreased expression of profibrotic signals TGF-β1, CCN2 and ET-1, downstream of angiotensin-II-receptor-1 inhibition. Consequently, losartan reduces solid stress in tumours resulting in increased vascular perfusion. Through this physical mechanism, losartan improves drug and oxygen delivery to tumours, thereby potentiating chemotherapy and reducing hypoxia in breast and pancreatic cancer models. Thus, angiotensin inhibitors —inexpensive drugs with decades of safe use — could be rapidly repurposed as cancer therapeutics. PMID:24084631

  17. The application of Fe3O4 nanoparticles in cancer research: a new strategy to inhibit drug resistance.

    PubMed

    Wang, Xuemei; Zhang, Renyun; Wu, Chunhui; Dai, Yongyuan; Song, Min; Gutmann, Sebastian; Gao, Feng; Lv, Gang; Li, Jingyuan; Li, Xiaomao; Guan, Zhiqun; Fu, Degang; Chen, Baoan

    2007-03-15

    Although much effort has been extended to the efficient cancer therapies, the drug resistance is still a major obstacle in cancer chemotherapeutic treatments. Almost 90% of the cancer therapy failure is caused by the relative problems. Recently, the application of drug coated polymer nanospheres and nanoparticles to inhibit the related drug resistance has attracted much attention. In this report, we have explored a novel strategy to inhibit the multidrug resistance of the targeted tumor cells by combining the unique properties of tetraheptylammonium capped Fe(3)O(4) magnetic nanoparticles with the drug accumulation of anticancer drug daunorubicin. Our results of confocal fluorescence and atomic force microscopy (AFM) as well as electrochemical studies demonstrate the remarkable synergistic effect of Fe(3)O(4) nanoparticles on drug uptake of daunorubicin in leukemia K562 cells. These observations indicate that the interaction between the magnetic nanoparticles Fe(3)O(4) and biologically active molecules on the membrane of leukemia cell lines may contribute to their beneficial effect on cellular uptake so that the synergistic enhanced effect of magnetic nanoparticles Fe(3)O(4) on drug uptake of drug resistance leukemia K562 cells could be observed upon application of the Fe(3)O(4) nanoparticles. PMID:17072850

  18. Melanin protects Paracoccidioides brasiliensis from the effects of antimicrobial photodynamic inhibition and antifungal drugs.

    PubMed

    Baltazar, Ludmila Matos; Werneck, Silvia Maria Cordeiro; Soares, Betânia Maria; Ferreira, Marcus Vinicius L; Souza, Danielle G; Pinotti, Marcos; Santos, Daniel Assis; Cisalpino, Patrícia Silva

    2015-07-01

    Paracoccidioidomycosis (PCM) is a public health concern in Latin America and South America that when not correctly treated can lead to patient death. In this study, the influence of melanin produced by Paracoccidioides spp. on the effects of treatment with antimicrobial photodynamic inhibition (aPI) and antifungal drugs was evaluated. aPI was performed using toluidine blue (TBO) as a photosensitizer and a 630-nm light-emitting diode (LED) light. The antifungals tested were itraconazole and amphotericin B. We evaluated the effects of each approach, aPI or antifungals, against nonmelanized and melanized yeast cells by performing susceptibility tests and by quantifying oxidative and nitrosative bursts during the experiments. aPI reduced nonmelanized cells by 3.0 log units and melanized cells by 1.3 log units. The results showed that melanization protects the fungal cell, probably by acting as a scavenger of nitric oxide and reactive oxygen species, but not of peroxynitrite. Melanin also increased the MICs of itraconazole and amphotericin B, and the drugs were fungicidal for nonmelanized and fungistatic for melanized yeast cells. Our study shows that melanin production by Paracoccidioides yeast cells serves a protective function during aPI and treatment with itraconazole and amphotericin B. The results suggest that melanin binds to the drugs, changing their antifungal activities, and also acts as a scavenger of reactive oxygen species and nitric oxide, but not of peroxynitrite, indicating that peroxynitrite is the main radical that is responsible for fungal death after aPI. PMID:25896704

  19. In Vitro Inhibition Of Three Different Drugs Used In Rheumatoid Arthritis Treatment On Human Serum Paraoxanase 1 Enzyme Activity.

    PubMed

    Dilek, Esra; Polat, M Fatih

    2016-01-01

    We studied in vitro effects of three different drugs (ibuprofen, meloxicam and methotrexate) which are often used in rheumatoid arthritis (RA) treatment on human serum paraoxanase1 (PON1) enzyme activity. The drugs used in RA treatment decreased the in vitro PON1 activity. The inhibition mechanism of ibuprofen and methotrexate were noncompetitive whereas meloxicam was a competitive inhibitor. The IC50 values for ibuprofen, meloxicam and methotrexate were calculated to be 0.35 mM, 0.10 mM, and 0.18 mM, respectively, and the Ki constants were calculated to be 0.890 mM, 0.125 mM, and 0.260 mM, respectively. The IC50 and Ki values showed the maximum inhibition of meloxicam drugs. We propose a prediction scheme for the interaction of meloxicam with the PON1 active site because we thought that meloxicam interacts with the amino acids which are in the PON1 enzyme active site. The results we found showed that these drugs which are often used in RA treatment in vitro inhibit the activity of the enzyme with different inhibition mechanisms at low doses. PMID:26458405

  20. Nanoparticle-Based ARV Drug Combinations for Synergistic Inhibition of Cell-Free and Cell-Cell HIV Transmission.

    PubMed

    Jiang, Yonghou; Cao, Shijie; Bright, Danielle K; Bever, Alaina M; Blakney, Anna K; Suydam, Ian T; Woodrow, Kim A

    2015-12-01

    Nanocarrier-based drug delivery systems are playing an emerging role in human immunodeficiency virus (HIV) chemoprophylaxis and treatment due to their ability to alter the pharmacokinetics and improve the therapeutic index of various antiretroviral (ARV) drug compounds used alone and in combination. Although several nanocarriers have been described for combination delivery of ARV drugs, measurement of drug-drug activities facilitated by the use of these nanotechnology platforms has not been fully investigated for topical prevention. Here, we show that physicochemically diverse ARV drugs can be encapsulated within polymeric nanoparticles to deliver multidrug combinations that provide potent HIV chemoprophylaxis in relevant models of cell-free, cell-cell, and mucosal tissue infection. In contrast to existing approaches that coformulate ARV drug combinations together in a single nanocarrier, we prepared single-drug-loaded nanoparticles that were subsequently combined upon administration. ARV drug-nanoparticles were prepared using emulsion-solvent evaporation techniques to incorporate maraviroc (MVC), etravirine (ETR), and raltegravir (RAL) into poly(lactic-co-glycolic acid) (PLGA) nanoparticles. We compared the antiviral potency of the free and formulated drug combinations for all pairwise and triple drug combinations against both cell-free and cell-associated HIV-1 infection in vitro. The efficacy of ARV-drug nanoparticle combinations was also assessed in a macaque cervicovaginal explant model using a chimeric simian-human immunodeficiency virus (SHIV) containing the reverse transcriptase (RT) of HIV-1. We observed that our ARV-NPs maintained potent HIV inhibition and were more effective when used in combinations. In particular, ARV-NP combinations involving ETR-NP exhibited significantly higher antiviral potency and dose-reduction against both cell-free and cell-associated HIV-1 BaL infection in vitro. Furthermore, ARV-NP combinations that showed large dose

  1. Effects of prostaglandins and COX-inhibiting drugs on skeletal muscle adaptations to exercise

    PubMed Central

    Liu, Sophia Z.

    2013-01-01

    It has been ∼40 yr since the discovery that PGs are produced by exercising skeletal muscle and since the discovery that inhibition of PG synthesis is the mechanism of action of what are now known as cyclooxygenase (COX)-inhibiting drugs. Since that time, it has been established that PGs are made during and after aerobic and resistance exercise and have a potent paracrine and autocrine effect on muscle metabolism. Consequently, it has also been determined that orally consumed doses of COX inhibitors can profoundly influence muscle PG synthesis, muscle protein metabolism, and numerous other cellular processes that regulate muscle adaptations to exercise loading. Although data from acute human exercise studies, as well as animal and cell-culture data, would predict that regular consumption of a COX inhibitor during exercise training would dampen the typical muscle adaptations, the chronic data do not support this conjecture. From the studies in young and older individuals, lasting from 1.5 to 4 mo, no interfering effects of COX inhibitors on muscle adaptations to resistance-exercise training have been noted. In fact, in older individuals, a substantial enhancement of muscle mass and strength has been observed. The collective findings of the PG/COX-pathway regulation of skeletal muscle responses and adaptations to exercise are compelling. Considering the discoveries in other areas of COX regulation of health and disease, there is certainly an interesting future of investigation in this re-emerging area, especially as it pertains to older individuals and the condition of sarcopenia, as well as exercise training and performance of individuals of all ages. PMID:23539318

  2. Peripherally administered oxytocin modulates latent inhibition in a manner consistent with antipsychotic drugs

    PubMed Central

    Feifel, D.; Shilling, P. D.; Hillman, J.; Maisel, M.; Winfield, J.; Melendez, G.

    2014-01-01

    Background Peripherally administered oxytocin (OT) has produced antipsychotic drug (APD)-like effects in animal tests that are predictive of APD efficacy. However, these effects have mainly been demonstrated using animal models of schizophrenia-like deficits in prepulse inhibition (PPI) of the startle reflex. Another schizophrenia-relevant abnormality that is the basis of a predictive animal test for APD efficacy is deficient latent inhibition (LI). LI is the normal suppression of a classically conditioned response when the subject is pre-exposed to the conditioned stimulus (CS) before it is paired with the unconditioned stimulus (UCS). Conditioned taste aversion (CTA), the normal avoidance of ingesting a food or liquid by animals when its taste is associated with an aversive experience, was used to test whether OT facilitates LI consistent with APDs. Methods Brown Norway rats, known to naturally display attenuated LI, were aversively conditioned on two consecutive exposures to flavored drinking water (0.1% saccharin) by pairing it with malaise-inducing lithium chloride injections. Concurrent with conditioning, rats received subcutaneous OT (0.02, 0.1, 0.5 mg/kg) or saline. Some rats were pre-exposed to the flavored water prior to its aversive conditioning (pre-exposed) while others were not (non pre-exposed). Two days after aversive conditioning the amount of flavored water consumed during a 20-minute session was recorded. Results As expected, LI, defined as greater consumption by pre-exposed vs. non pre-exposed rats was only weakly exhibited in Brown Norway rats and OT enhanced LI by reducing CTA in pre-exposed rats in a dose-dependent manner, with the 0.02 mg/kg dose producing the strongest effect. Conclusions The facilitation of LI by OT is consistent with the effects produced by APDs and provides further support for the notion that OT has therapeutic potential for schizophrenia. PMID:25447298

  3. Autophagy inhibition uncovers the neurotoxic action of the antipsychotic drug olanzapine

    PubMed Central

    Vucicevic, Ljubica; Misirkic-Marjanovic, Maja; Paunovic, Verica; Kravic-Stevovic, Tamara; Martinovic, Tamara; Ciric, Darko; Maric, Nadja; Petricevic, Sasa; Harhaji-Trajkovic, Ljubica; Bumbasirevic, Vladimir; Trajkovic, Vladimir

    2015-01-01

    We investigated the role of autophagy, a controlled cellular self-digestion process, in regulating survival of neurons exposed to atypical antipsychotic olanzapine. Olanzapine induced autophagy in human SH-SY5Y neuronal cell line, as confirmed by the increase in autophagic flux and presence of autophagic vesicles, fusion of autophagosomes with lysosomes, and increase in the expression of autophagy-related (ATG) genes ATG4B, ATG5, and ATG7. The production of reactive oxygen species, but not modulation of the main autophagy repressor MTOR or its upstream regulators AMP-activated protein kinase and AKT1, was responsible for olanzapine-triggered autophagy. Olanzapine-mediated oxidative stress also induced mitochondrial depolarization and damage, and the autophagic clearance of dysfunctional mitochondria was confirmed by electron microscopy, colocalization of autophagosome-associated MAP1LC3B (LC3B henceforth) and mitochondria, and mitochondrial association with the autophagic cargo receptor SQSTM1/p62. While olanzapine-triggered mitochondrial damage was not overtly toxic to SH-SY5Y cells, their death was readily initiated upon the inhibition of autophagy with pharmacological inhibitors, RNA interference knockdown of BECN1 and LC3B, or biological free radical nitric oxide. The treatment of mice with olanzapine for 14 d increased the brain levels of autophagosome-associated LC3B-II and mRNA encoding Atg4b, Atg5, Atg7, Atg12, Gabarap, and Becn1. The administration of the autophagy inhibitor chloroquine significantly increased the expression of proapoptotic genes (Trp53, Bax, Bak1, Pmaip1, Bcl2l11, Cdkn1a, and Cdkn1b) and DNA fragmentation in the frontal brain region of olanzapine-exposed animals. These data indicate that olanzapine-triggered autophagy protects neurons from otherwise fatal mitochondrial damage, and that inhibition of autophagy might unmask the neurotoxic action of the drug. PMID:25551567

  4. STAT3 Inhibition by Microtubule-Targeted Drugs: Dual Molecular Effects of Chemotherapeutic Agents

    PubMed Central

    Walker, Sarah R.; Chaudhury, Mousumi; Frank, David A.

    2011-01-01

    To improve the effectiveness of anti-cancer therapies, it is necessary to identify molecular targets that are essential to a tumor cell but dispensable in a normal cell. Increasing evidence indicates that the transcription factor STAT3, which regulates the expression of genes controlling proliferation, survival, and self-renewal, constitutes such a target. Recently it has been found that STAT3 can associate with the cytoskeleton. Since many of the tumors in which STAT3 is activated, such as breast cancer and ovarian cancer, are responsive to drugs that target microtubules, we examined the effect of these compounds on STAT3. We found that microtubule stabilizers, such as paclitaxel, or microtubule inhibitors, such as vinorelbine, decrease the activating tyrosine phosphorylation of STAT3 in tumor cells and inhibit the expression of STAT3 target genes. Paclitaxel decreases the association between STAT3 and microtubules, and appears to decrease STAT3 phosphorylation through induction of a negative feedback regulator. The cytotoxic activity of paclitaxel in breast cancer cell lines correlates with its ability to decrease STAT3 phosphorylation. However, consistent with the necessity for expression of a negative regulator, treatment of resistant MDA-MB-231 cells with the DNA demethylating agent 5-azacytidine restores the ability of paclitaxel to block STAT3-dependent gene expression. Finally, the combination of paclitaxel and agents that directly target STAT3 has beneficial effects in killing STAT3-dependent cell lines. Thus, microtubule-targeted agents may exert some of their effects by inhibiting STAT3, and understanding this interaction may be important for optimizing rational targeted cancer therapies. PMID:21949561

  5. Autophagy inhibition uncovers the neurotoxic action of the antipsychotic drug olanzapine.

    PubMed

    Vucicevic, Ljubica; Misirkic-Marjanovic, Maja; Paunovic, Verica; Kravic-Stevovic, Tamara; Martinovic, Tamara; Ciric, Darko; Maric, Nadja; Petricevic, Sasa; Harhaji-Trajkovic, Ljubica; Bumbasirevic, Vladimir; Trajkovic, Vladimir

    2014-01-01

    We investigated the role of autophagy, a controlled cellular self-digestion process, in regulating survival of neurons exposed to atypical antipsychotic olanzapine. Olanzapine induced autophagy in human SH-SY5Y neuronal cell line, as confirmed by the increase in autophagic flux and presence of autophagic vesicles, fusion of autophagosomes with lysosomes, and increase in the expression of autophagy-related (ATG) genes ATG4B, ATG5, and ATG7. The production of reactive oxygen species, but not modulation of the main autophagy repressor MTOR or its upstream regulators AMP-activated protein kinase and AKT1, was responsible for olanzapine-triggered autophagy. Olanzapine-mediated oxidative stress also induced mitochondrial depolarization and damage, and the autophagic clearance of dysfunctional mitochondria was confirmed by electron microscopy, colocalization of autophagosome-associated MAP1LC3B (LC3B henceforth) and mitochondria, and mitochondrial association with the autophagic cargo receptor SQSTM1/p62. While olanzapine-triggered mitochondrial damage was not overtly toxic to SH-SY5Y cells, their death was readily initiated upon the inhibition of autophagy with pharmacological inhibitors, RNA interference knockdown of BECN1 and LC3B, or biological free radical nitric oxide. The treatment of mice with olanzapine for 14 d increased the brain levels of autophagosome-associated LC3B-II and mRNA encoding Atg4b, Atg5, Atg7, Atg12, Gabarap, and Becn1. The administration of the autophagy inhibitor chloroquine significantly increased the expression of proapoptotic genes (Trp53, Bax, Bak1, Pmaip1, Bcl2l11, Cdkn1a, and Cdkn1b) and DNA fragmentation in the frontal brain region of olanzapine-exposed animals. These data indicate that olanzapine-triggered autophagy protects neurons from otherwise fatal mitochondrial damage, and that inhibition of autophagy might unmask the neurotoxic action of the drug. PMID:25551567

  6. Mutually Exclusive, Complementary, or . . .

    ERIC Educational Resources Information Center

    Schloemer, Cathy G.

    2016-01-01

    Whether students are beginning their study of probability or are well into it, distinctions between complementary sets and mutually exclusive sets can be confusing. Cathy Schloemer writes in this article that for years she used typical classroom examples but was not happy with the student engagement or the level of understanding they produced.…

  7. Mutual Adaptaion in Action

    ERIC Educational Resources Information Center

    Siskin, Leslie Santee

    2016-01-01

    Building on an expanded concept of mutual adaptation, this chapter explores a distinctive and successful aspect of International Baccalaureate's effort to scale up, as they moved to expand their programs and support services in Title I schools. Based on a three-year, mixed-methods study, it offers a case where we see not only local adaptations…

  8. Efficient inhibition of colorectal peritoneal carcinomatosis by drug loaded micelles in thermosensitive hydrogel composites

    NASA Astrophysics Data System (ADS)

    Gong, Changyang; Wang, Cheng; Wang, Yujun; Wu, Qinjie; Zhang, Doudou; Luo, Feng; Qian, Zhiyong

    2012-05-01

    In this work, we aim to develop a dual drug delivery system (DDDS) of self-assembled micelles in thermosensitive hydrogel composite to deliver hydrophilic and hydrophobic drugs simultaneously for colorectal peritoneal carcinomatosis (CRPC) therapy. In our previous studies, we found that poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCEC) copolymers with different molecular weight and PEG/PCL ratio could be administered to form micelles or thermosensitive hydrogels, respectively. Therefore, the DDDS was constructed from paclitaxel (PTX) encapsulated PCEC micelles (PTX-micelles) and a fluorouracil (Fu) loaded thermosensitive PCEC hydrogel (Fu-hydrogel). PTX-micelles were prepared by self-assembly of biodegradable PCEC copolymer (Mn = 3700) and PTX without using any surfactants or excipients. Meanwhile, biodegradable and injectable thermosensitive Fu-hydrogel (Mn = 3000) with a lower sol-gel transition temperature at around physiological temperature was also prepared. The obtained PTX-micelles in thermosensitive Fu-hydrogel (PTX-micelles-Fu-hydrogel) composite is a free-flowing sol at ambient temperature and rapidly turned into a non-flowing gel at physiological temperature. In addition, the results of cytotoxicity, hemolytic study, and acute toxicity evaluation suggested that the PTX-micelles-Fu-hydrogel was non-toxic and biocompatible. In vitro release behaviors of PTX-micelles-Fu-hydrogel indicated that both PTX and Fu have a sustained release behavior. Furthermore, intraperitoneal application of PTX-micelles-Fu-hydrogel effectively inhibited growth and metastasis of CT26 peritoneal carcinomatosis in vivo (p < 0.001), and induced a stronger antitumor effect than that of Taxol® plus Fu (p < 0.001). The pharmacokinetic study indicated that PTX-micelles-Fu-hydrogel significantly increased PTX and Fu concentration and residence time in peritoneal fluids compared with Taxol® plus Fu group. Thus, the results suggested the micelles-hydrogel DDDS may

  9. Investigation of the impact of substrate selection on in vitro organic anion transporting polypeptide 1B1 inhibition profiles for the prediction of drug-drug interactions.

    PubMed

    Izumi, Saki; Nozaki, Yoshitane; Maeda, Kazuya; Komori, Takafumi; Takenaka, Osamu; Kusuhara, Hiroyuki; Sugiyama, Yuichi

    2015-02-01

    The risk assessment of organic anion transporting polypeptide (OATP) 1B1-mediated drug-drug interactions (DDIs) is an indispensable part of drug development. We previously reported that in vitro inhibitory potencies of several inhibitors on OATP1B1 depend on the substrates when prototypical substrates, estradiol-17β-glucuronide (E₂G), estrone-3-sulfate, and sulfobromophthalein were used as test substrates. The purpose of this study was to comprehensively investigate this substrate-dependent inhibition of OATP1B1 using clinically relevant OATP1B1 inhibitors and substrate drugs. Effects of cyclosporine A (CsA), rifampin, and gemfibrozil on OATP1B1-mediated uptake of 12 substrate drugs were examined in OATP1B1-expressing human embryonic kidney 293 cells. The Ki values (μM) for CsA varied from 0.0771 to 0.486 (6.3-fold), for rifampin from 0.358 to 1.23 (3.4-fold), and for gemfibrozil from 9.65 to 252 (26-fold). Except for the inhibition of torasemide uptake by CsA and that of nateglinide uptake by gemfibrozil, the Ki values were within 2.8-fold of those obtained using E₂G as a substrate. Preincubation potentiated the inhibitory effect of CsA on OATP1B1 with similar magnitude regardless of the substrates. R values calculated based on a static model showed some variation depending on the Ki values determined with various substrates, and such variability could have an impact on the DDI predictions particularly for a weak-to-moderate inhibitor (gemfibrozil). OATP1B1 substrate drugs except for torasemide and nateglinide, or E₂G as a surrogate, is recommended as an in vitro probe in the inhibition experiments, which will help mitigate the risk of false-negative DDI predictions potentially caused by substrate-dependent Ki variation. PMID:25414411

  10. Inhibition of respiratory burst activity in alveolar macrophages by bisbenzylisoquinoline alkaloids: characterization of drug-cell interaction.

    PubMed

    Ma, J Y; Barger, M W; Ma, J K; Castranova, V

    1992-01-01

    The objective of this study was to investigate the effects of various bisbenzylisoquinoline (BBIQ) alkaloids on respiratory burst activity of alveolar macrophages and to characterize the interaction of these drugs with alveolar phagocytes. BBIQ alkaloids were chosen for study because they exhibit a wide range of antifibrotic potencies in a rat model, with tetrandrine being very effective and tubocurarine being ineffective. These drugs inhibited zymosan-stimulated oxygen consumption with a potency sequence of tetrandrine (TT) approximately fangchinoline (FA) > berbamine (BE) approximately cepharanthine (CE) approximately cycleanine (CY) > tubocurarine (TU). This inhibition of respiratory burst activity could not be attributed to a drug-induced decline in the ATP content of these pneumocytes. Drug binding to alveolar macrophages was directly dependent on temperature and drug concentration. The sequence for binding capacity was FA > TT approximately BE approximately CY > CE > TU. Therefore, there was no simple relationship between binding capacity and inhibitory potency. Binding capacity was not related to lipophilicity of these alkaloids. In addition, tetrandrine failed to bind to metabolically dead cells or sonicated macrophage preparations. These data suggest that the interaction of BBIQ alkaloids with phagocytes is not simply nonspecific binding to membrane lipids. Alteration of the cytoskeletal system with vinblastine, taxol, or cytochalasin B decreased tetrandrine binding by approximately 33% when added separately and by 93% when added jointly. Pre-exposure of alveolar macrophages to stimulants increased the ability of BBIQ alkaloids to inhibit both oxygen consumption and superoxide release. These data suggest that the mechanism by which BBIQ alkaloids inhibit activation of phagocytes involves microtubules and bules and microfilaments. Pre-exposure of macrophages to stimulants would change the conformation of cytoskeletal components and may make these structures

  11. Efficacy and selectivity of phosphodiesterase-targeted drugs to inhibit photoreceptor phosphodiesterase (PDE6) in retinal photoreceptors*

    PubMed Central

    Zhang, Xiujun; Feng, Qing; Cote, Rick H.

    2005-01-01

    Purpose: Phosphodiesterase (PDE) inhibitors are important therapeutic agents, but their effects on photoreceptor PDE (PDE6) and photoreceptor cells are poorly understood. We characterized the potency and selectivity of various classes of PDE inhibitors on purified rod and cone PDE6 and on intact rod outer segments (ROS). Methods: The inhibition constant (KI) of isozyme-selective PDE inhibitors was determined for purified rod and cone PDE6. Perturbations of cGMP levels in isolated ROS suspensions by PDE inhibitors were quantitated by a cGMP enzyme-linked immunoassay. Results: Most PDE5-selective inhibitors are excellent PDE6 inhibitors. Vardenafil, a potent PDE5 inhibitor (KI = 0.2 nM), is the most potent PDE6 inhibitor tested (KI = 0.7 nM). Zaprinast is the only drug that inhibits PDE6 more potently than PDE5. PDE1-selective inhibitors were equally effective in inhibiting PDE6. In intact ROS, PDE inhibitors elevated cGMP levels but none fully inhibited PDE6. Their potency to elevate cGMP levels in ROS was much lower than their ability to inhibit the purified enzyme. Competition between PDE5/6-selective drugs and the inhibitory γ subunit for the active site of PDE6 is proposed to reduce the effectiveness of drugs at the enzyme active site. Conclusions: Several classes of PDE inhibitors equally well inhibit PDE6 as the PDE family to which they are targeted. In intact ROS, high PDE6 concentrations, binding of the γ subunit to the active site, and calcium feedback mechanisms attenuate the effectiveness of PDE inhibitors to inhibit PDE6 and disrupt the cGMP signaling pathway during visual transduction. PMID:16123402

  12. Gemfibrozil, a Lipid-lowering Drug, Inhibits the Induction of Nitric-oxide Synthase in Human Astrocytes*

    PubMed Central

    Pahan, Kalipada; Jana, Malabendu; Liu, Xiaojuan; Taylor, Bradley S.; Wood, Charles; Fischer, Susan M.

    2007-01-01

    Gemfibrozil, a lipid-lowering drug, inhibited cytokine-induced production of NO and the expression of inducible nitric-oxide synthase (iNOS) in human U373MG astroglial cells and primary astrocytes. Similar to gemfibrozil, clofibrate, another fibrate drug, also inhibited the expression of iNOS. Inhibition of human iNOS promoter-driven luciferase activity by gemfibrozil in cytokine-stimulated U373MG astroglial cells suggests that this compound inhibits the transcription of iNOS. Since gemfibrozil is known to activate peroxisome proliferator-activated receptor-α (PPAR-α), we investigated the role of PPAR-α in gemfibrozil-mediated inhibition of iNOS. Gemfibrozil induced peroxisome proliferator-responsive element (PPRE)-dependent luciferase activity, which was inhibited by the expression of ΔhPPAR-α, the dominant-negative mutant of human PPAR-α. However, ΔhPPAR-α was unable to abrogate gemfibrozil-mediated inhibition of iNOS suggesting that gemfibrozil inhibits iNOS independent of PPAR-α. The human iNOS promoter contains consensus sequences for the binding of transcription factors, including interferon-γ (IFN-γ) regulatory factor-1 (IRF-1) binding to interferon-stimulated responsive element (ISRE), signal transducer and activator of transcription (STAT) binding to γ-activation site (GAS), nuclear factor-κB (NF-κB), activator protein-1 (AP-1), and CCAAT/enhancer-binding protein β (C/EBPβ); therefore, we investigated the effect of gemfibrozil on the activation of these transcription factors. The combination of interleukin (IL)-1β and IFN-γ induced the activation of NF-κB, AP-1, C/EBPβ, and GAS but not that of ISRE, suggesting that IRF-1 may not be involved in cytokine-induced expression of iNOS in human astrocytes. Interestingly, gemfibrozil strongly inhibited the activation of NF-κB, AP-1, and C/EBPβ but not that of GAS in cytokine-stimulated astroglial cells. These results suggest that gemfibrozil inhibits the induction of iNOS probably by

  13. A high-throughput chemical screen with FDA approved drugs reveals that the antihypertensive drug Spironolactone impairs cancer cell survival by inhibiting homology directed repair

    PubMed Central

    Shahar, Or David; Kalousi, Alkmini; Eini, Lital; Fisher, Benoit; Weiss, Amelie; Darr, Jonatan; Mazina, Olga; Bramson, Shay; Kupiec, Martin; Eden, Amir; Meshorer, Eran; Mazin, Alexander V.; Brino, Laurent; Goldberg, Michal; Soutoglou, Evi

    2014-01-01

    DNA double-strand breaks (DSBs) are the most severe type of DNA damage. DSBs are repaired by non-homologous end-joining or homology directed repair (HDR). Identifying novel small molecules that affect HDR is of great importance both for research use and therapy. Molecules that elevate HDR may improve gene targeting whereas inhibiting molecules can be used for chemotherapy, since some of the cancers are more sensitive to repair impairment. Here, we performed a high-throughput chemical screen for FDA approved drugs, which affect HDR in cancer cells. We found that HDR frequencies are increased by retinoic acid and Idoxuridine and reduced by the antihypertensive drug Spironolactone. We further revealed that Spironolactone impairs Rad51 foci formation, sensitizes cancer cells to DNA damaging agents, to Poly (ADP-ribose) polymerase (PARP) inhibitors and cross-linking agents and inhibits tumor growth in xenografts, in mice. This study suggests Spironolactone as a new candidate for chemotherapy. PMID:24682826

  14. Antidiabetic drug metformin inhibits esophageal adenocarcinoma cell proliferation in vitro and in vivo.

    PubMed

    Fujihara, Shintaro; Kato, Kiyohito; Morishita, Asahiro; Iwama, Hisakazu; Nishioka, Tomoko; Chiyo, Taiga; Nishiyama, Noriko; Miyoshi, Hisaaki; Kobayashi, Mitsuyoshi; Kobara, Hideki; Mori, Hirohito; Okano, Keiichi; Suzuki, Yasuyuki; Masaki, Tsutomu

    2015-05-01

    Esophageal carcinoma is the eighth most common cancer worldwide and the sixth leading cause of cancer-related deaths, with one of the worst prognoses of any form of cancer. Treatment with the anti-diabetic drug metformin has been associated with reduced cancer incidence in patients with type 2 diabetes. This study therefore evaluated the effects of metformin on the proliferation, in vitro and in vivo, of human esophageal adenocarcinoma cells, as well as the microRNAs associated with the antitumor effects of metformin. Metformin inhibited the proliferation of the esophageal adenocarcinoma cell lines OE19, OE33, SK-GT4 and OACM 5.1C, blocking the G0 to G1 transition in the cell cycle. This was accompanied by strong reductions in G1 cyclins, especially cyclin D1, cyclin-dependent kinase (Cdk)4, and Cdk6, and decreases in retinoblastoma protein phosphorylation. In addition, metformin reduced the phosphorylation of epidermal growth factor receptor and insulin-like growth factor and insulin-like growth factor-1 receptor, as well as angiogenesis-related proteins, such as vascular endothelial growth factor, tissue inhibitor of metalloproteinases (TIMP)-1, and TIMP-2. Metformin also markedly altered microRNA expression. Treatment with metformin of athymic nude mice bearing xenograft tumors reduced tumor proliferation. These findings suggest that metformin may have clinical use in the treatment of esophageal adenocarcinoma. PMID:25709052

  15. The anthelmintic drug mebendazole inhibits growth, migration and invasion in gastric cancer cell model.

    PubMed

    Pinto, Laine Celestino; Soares, Bruno Moreira; Pinheiro, João de Jesus Viana; Riggins, Gregory J; Assumpção, Paulo Pimentel; Burbano, Rommel Mário Rodriguez; Montenegro, Raquel Carvalho

    2015-12-01

    The present study aimed to investigate the effects of MBZ on a human malignant ascites cell line derived from a primary gastric cancer tumor. Our data reveal that MBZ showed high cytotoxicity in vitro, displaying an IC50 of 0.39 μM and 1.25 μM in ACP-02 and ACP-03, respectively. The association between MBZ and 5-FU increased slightly the cytotoxicity when compared to MBZ and 5-FU alone. Furthermore, MBZ disrupted the microtubule structure of AGP-01 cells and inhibited significantly the invasion and migration of these cells. Activity of active MMP-2 significantly decreased at all tested concentration of MBZ compared to negative control. These results support the indication of MBZ in combination with chemotherapeutic agents as a possible adjuvant therapy for the management/treatment of patients with advanced gastric cancer since MBZ is a drug of low cost with acceptable safety profile and reduced toxicity to normal cells. However, clinical trials must be performed in o to evaluate its efficacy in gastric cancer patients. PMID:26315676

  16. Structural basis of DNA gyrase inhibition by antibacterial QPT-1, anticancer drug etoposide and moxifloxacin.

    PubMed

    Chan, Pan F; Srikannathasan, Velupillai; Huang, Jianzhong; Cui, Haifeng; Fosberry, Andrew P; Gu, Minghua; Hann, Michael M; Hibbs, Martin; Homes, Paul; Ingraham, Karen; Pizzollo, Jason; Shen, Carol; Shillings, Anthony J; Spitzfaden, Claus E; Tanner, Robert; Theobald, Andrew J; Stavenger, Robert A; Bax, Benjamin D; Gwynn, Michael N

    2015-01-01

    New antibacterials are needed to tackle antibiotic-resistant bacteria. Type IIA topoisomerases (topo2As), the targets of fluoroquinolones, regulate DNA topology by creating transient double-strand DNA breaks. Here we report the first co-crystal structures of the antibacterial QPT-1 and the anticancer drug etoposide with Staphylococcus aureus DNA gyrase, showing binding at the same sites in the cleaved DNA as the fluoroquinolone moxifloxacin. Unlike moxifloxacin, QPT-1 and etoposide interact with conserved GyrB TOPRIM residues rationalizing why QPT-1 can overcome fluoroquinolone resistance. Our data show etoposide's antibacterial activity is due to DNA gyrase inhibition and suggests other anticancer agents act similarly. Analysis of multiple DNA gyrase co-crystal structures, including asymmetric cleavage complexes, led to a 'pair of swing-doors' hypothesis in which the movement of one DNA segment regulates cleavage and religation of the second DNA duplex. This mechanism can explain QPT-1's bacterial specificity. Structure-based strategies for developing topo2A antibacterials are suggested. PMID:26640131

  17. Structural basis of DNA gyrase inhibition by antibacterial QPT-1, anticancer drug etoposide and moxifloxacin

    PubMed Central

    Chan, Pan F.; Srikannathasan, Velupillai; Huang, Jianzhong; Cui, Haifeng; Fosberry, Andrew P.; Gu, Minghua; Hann, Michael M.; Hibbs, Martin; Homes, Paul; Ingraham, Karen; Pizzollo, Jason; Shen, Carol; Shillings, Anthony J.; Spitzfaden, Claus E.; Tanner, Robert; Theobald, Andrew J.; Stavenger, Robert A.; Bax, Benjamin D.; Gwynn, Michael N.

    2015-01-01

    New antibacterials are needed to tackle antibiotic-resistant bacteria. Type IIA topoisomerases (topo2As), the targets of fluoroquinolones, regulate DNA topology by creating transient double-strand DNA breaks. Here we report the first co-crystal structures of the antibacterial QPT-1 and the anticancer drug etoposide with Staphylococcus aureus DNA gyrase, showing binding at the same sites in the cleaved DNA as the fluoroquinolone moxifloxacin. Unlike moxifloxacin, QPT-1 and etoposide interact with conserved GyrB TOPRIM residues rationalizing why QPT-1 can overcome fluoroquinolone resistance. Our data show etoposide's antibacterial activity is due to DNA gyrase inhibition and suggests other anticancer agents act similarly. Analysis of multiple DNA gyrase co-crystal structures, including asymmetric cleavage complexes, led to a ‘pair of swing-doors' hypothesis in which the movement of one DNA segment regulates cleavage and religation of the second DNA duplex. This mechanism can explain QPT-1's bacterial specificity. Structure-based strategies for developing topo2A antibacterials are suggested. PMID:26640131

  18. Inhibition of wnt/β-catenin Signaling in Hepatocellular Carcinoma by an Antipsychotic Drug Pimozide

    PubMed Central

    Fako, Valerie; Yu, Zhipeng; Henrich, Curtis J.; Ransom, Tanya; Budhu, Anuradha S.; Wang, Xin W.

    2016-01-01

    Hepatocellular carcinoma (HCC) is one of the most common forms of malignant cancers in the world, yet very few effective systemic treatments for HCC patients exist. Thus, the development of new treatment modalities presents a great need. The wnt/β-catenin signaling pathway is highly activated in stem cell-like aggressive HCC, which is associated with chemoresistance and poor survival in HCC patients. In a previous study, we found that an FDA-approved psychiatric drug, pimozide (PMZ), has anti-cancer properties in HCC cell lines that express epithelial cell adhesion molecule (EpCAM), a hepatic stem cell marker that is a functional down-stream target of the wnt/β-catenin pathway. In this study, we demonstrate that PMZ effectively inhibits cell growth of HCC cells by disrupting the wnt/β-catenin signaling pathway and reducing EpCAM expression. Thus, PMZ may be a useful molecular entity that could be repurposed as an anti-cancer therapy for treatment of HCC. PMID:27313491

  19. Phosphorus-32, a Clinically Available Drug, Inhibits Cancer Growth by Inducing DNA Double-Strand Breakage

    PubMed Central

    Cheng, Yulan; Kiess, Ana P.; Herman, Joseph M.; Pomper, Martin G.; Meltzer, Stephen J.; Abraham, John M.

    2015-01-01

    Radioisotopes that emit electrons (beta particles), such as radioiodine, can effectively kill target cells, including cancer cells. Aqueous 32P[PO4] is a pure beta-emitter that has been used for several decades to treat non-malignant human myeloproliferative diseases. 32P[PO4] was directly compared to a more powerful pure beta-emitter, the clinically important 90Y isotope. In vitro, 32P[PO4] was more effective at killing cells than was the more powerful isotope 90Y (P ≤ 0.001) and also caused substantially more double-stranded DNA breaks than did 90Y. In vivo, a single low-dose intravenous dose of aqueous elemental 32P significantly inhibited tumor growth in the syngeneic murine cancer model (P ≤ 0.001). This effect is exerted by direct incorporation into nascent DNA chains, resulting in double-stranded breakage, a unique mechanism not duplicatable by other, more powerful electron-emitting radioisotopes. 32P[PO4] should be considered for human clinical trials as a potential novel anti-cancer drug. PMID:26030880

  20. Anti-addiction drug ibogaine inhibits voltage-gated ionic currents: a study to assess the drug's cardiac ion channel profile.

    PubMed

    Koenig, Xaver; Kovar, Michael; Rubi, Lena; Mike, Agnes K; Lukacs, Peter; Gawali, Vaibhavkumar S; Todt, Hannes; Hilber, Karlheinz; Sandtner, Walter

    2013-12-01

    The plant alkaloid ibogaine has promising anti-addictive properties. Albeit not licensed as a therapeutic drug, and despite hints that ibogaine may perturb the heart rhythm, this alkaloid is used to treat drug addicts. We have recently reported that ibogaine inhibits human ERG (hERG) potassium channels at concentrations similar to the drugs affinity for several of its known brain targets. Thereby the drug may disturb the heart's electrophysiology. Here, to assess the drug's cardiac ion channel profile in more detail, we studied the effects of ibogaine and its congener 18-Methoxycoronaridine (18-MC) on various cardiac voltage-gated ion channels. We confirmed that heterologously expressed hERG currents are reduced by ibogaine in low micromolar concentrations. Moreover, at higher concentrations, the drug also reduced human Nav1.5 sodium and Cav1.2 calcium currents. Ion currents were as well reduced by 18-MC, yet with diminished potency. Unexpectedly, although blocking hERG channels, ibogaine did not prolong the action potential (AP) in guinea pig cardiomyocytes at low micromolar concentrations. Higher concentrations (≥ 10 μM) even shortened the AP. These findings can be explained by the drug's calcium channel inhibition, which counteracts the AP-prolonging effect generated by hERG blockade. Implementation of ibogaine's inhibitory effects on human ion channels in a computer model of a ventricular cardiomyocyte, on the other hand, suggested that ibogaine does prolong the AP in the human heart. We conclude that therapeutic concentrations of ibogaine have the propensity to prolong the QT interval of the electrocardiogram in humans. In some cases this may lead to cardiac arrhythmias. PMID:23707769

  1. Anti-addiction drug ibogaine inhibits voltage-gated ionic currents: A study to assess the drug's cardiac ion channel profile☆

    PubMed Central

    Koenig, Xaver; Kovar, Michael; Rubi, Lena; Mike, Agnes K.; Lukacs, Peter; Gawali, Vaibhavkumar S.; Todt, Hannes; Hilber, Karlheinz; Sandtner, Walter

    2013-01-01

    The plant alkaloid ibogaine has promising anti-addictive properties. Albeit not licenced as a therapeutic drug, and despite hints that ibogaine may perturb the heart rhythm, this alkaloid is used to treat drug addicts. We have recently reported that ibogaine inhibits human ERG (hERG) potassium channels at concentrations similar to the drugs affinity for several of its known brain targets. Thereby the drug may disturb the heart's electrophysiology. Here, to assess the drug's cardiac ion channel profile in more detail, we studied the effects of ibogaine and its congener 18-Methoxycoronaridine (18-MC) on various cardiac voltage-gated ion channels. We confirmed that heterologously expressed hERG currents are reduced by ibogaine in low micromolar concentrations. Moreover, at higher concentrations, the drug also reduced human Nav1.5 sodium and Cav1.2 calcium currents. Ion currents were as well reduced by 18-MC, yet with diminished potency. Unexpectedly, although blocking hERG channels, ibogaine did not prolong the action potential (AP) in guinea pig cardiomyocytes at low micromolar concentrations. Higher concentrations (≥ 10 μM) even shortened the AP. These findings can be explained by the drug's calcium channel inhibition, which counteracts the AP-prolonging effect generated by hERG blockade. Implementation of ibogaine's inhibitory effects on human ion channels in a computer model of a ventricular cardiomyocyte, on the other hand, suggested that ibogaine does prolong the AP in the human heart. We conclude that therapeutic concentrations of ibogaine have the propensity to prolong the QT interval of the electrocardiogram in humans. In some cases this may lead to cardiac arrhythmias. PMID:23707769

  2. Quantification of Drug-Induced Inhibition of Canalicular Cholyl-l-Lysyl-Fluorescein Excretion From Hepatocytes by High Content Cell Imaging.

    PubMed

    Barber, Jane A; Stahl, Simone H; Summers, Claire; Barrett, Gillian; Park, B Kevin; Foster, John R; Kenna, J Gerald

    2015-11-01

    We describe the use of a commercially available high content cell imaging algorithm (Cellomics Arrayscan Spot Detector) to quantify biliary excretion of the fluorescent probe substrate cholyl-l-lysyl-fluorescein (CLF) from rat hepatocytes cultured in collagen/matrigel sandwich configuration and to explore inhibition of this process by a variety of test compounds. The method provided robust, reproducible data. Twenty-nine pharmaceuticals inhibited biliary CLF efflux from hepatocytes and a broad range of potencies of inhibition were observed (IC50 values ranged between <1 and 794 µM). Thirteen drugs that inhibited CLF efflux also inhibited hepatocellular uptake of the probe substrate [(3)H]-taurocholate. Although no clear correlation between the potencies of inhibition of the 2 processes was evident, these data highlight the need to consider possible uptake transporter inhibition when interpreting hepatocyte CLF inhibition data. It has been reported that CLF is transported by MRP2. The CLF efflux inhibition data correlated closely with published data on inhibition by the drugs of the bile salt export pump (Bsep), which suggests that the tested drugs inhibit both Bsep and Mrp2. Calculation of the ratios between the maximum human plasma concentrations of the drugs and their CLF efflux inhibition IC50 values raised the possibility that for many, but not all, of them the in vitro effects may be functionally significant in vivo and that Mrp2 inhibition might be a drug-induced liver injury (DILI) risk factor. These data indicate that imaging hepatocyte CLF inhibition is a promising new method for quantification of biliary efflux inhibition by drugs, which could aid assessment of compound-related DILI risk. PMID:26220638

  3. Inhibition of Lysyl Oxidases Improves Drug Diffusion and Increases Efficacy of Cytotoxic Treatment in 3D Tumor Models

    PubMed Central

    Schütze, Friedrich; Röhrig, Florian; Vorlová, Sandra; Gätzner, Sabine; Kuhn, Anja; Ergün, Süleyman; Henke, Erik

    2015-01-01

    Tumors are characterized by a rigid, highly cross-linked extracellular matrix (ECM), which impedes homogeneous drug distribution and potentially protects malignant cells from exposure to therapeutics. Lysyl oxidases are major contributors to tissue stiffness and the elevated expression of these enzymes observed in most cancers might influence drug distribution and efficacy. We examined the effect of lysyl oxidases on drug distribution and efficacy in 3D in vitro assay systems. In our experiments elevated lysyl oxidase activity was responsible for reduced drug diffusion under hypoxic conditions and consequently impaired cytotoxicity of various chemotherapeutics. This effect was only observed in 3D settings but not in 2D-cell culture, confirming that lysyl oxidases affect drug efficacy by modification of the ECM and do not confer a direct desensitizing effect. Both drug diffusion and efficacy were strongly enhanced by inhibition of lysyl oxidases. The results from the in vitro experiments correlated with tumor drug distribution in vivo, and predicted response to therapeutics in murine tumor models. Our results demonstrate that lysyl oxidase activity modulates the physical barrier function of ECM for small molecule drugs influencing their therapeutic efficacy. Targeting this process has the potential to significantly enhance therapeutic efficacy in the treatment of malignant diseases. PMID:26620400

  4. Inhibition of bacterial growth by iron oxide nanoparticles with and without attached drug: Have we conquered the antibiotic resistance problem?

    NASA Astrophysics Data System (ADS)

    Armijo, Leisha M.; Jain, Priyanka; Malagodi, Angelina; Fornelli, F. Zuly; Hayat, Allison; Rivera, Antonio C.; French, Michael; Smyth, Hugh D. C.; Osiński, Marek

    2015-03-01

    Pseudomonas aeruginosa is among the top three leading causative opportunistic human pathogens, possessing one of the largest bacterial genomes and an exceptionally large proportion of regulatory genes therein. It has been known for more than a decade that the size and complexity of the P. aeruginosa genome is responsible for the adaptability and resilience of the bacteria to include its ability to resist many disinfectants and antibiotics. We have investigated the susceptibility of P. aeruginosa bacterial biofilms to iron oxide (magnetite) nanoparticles (NPs) with and without attached drug (tobramycin). We also characterized the susceptibility of zero-valent iron NPs, which are known to inactivate microbes. The particles, having an average diameter of 16 nm were capped with natural alginate, thus doubling the hydrodynamic size. Nanoparticle-drug conjugates were produced via cross-linking drug and alginate functional groups. Drug conjugates were investigated in the interest of determining dosage, during these dosage-curve experiments, NPs unbound to drug were tested in cultures as a negative control. Surprisingly, we found that the iron oxide NPs inhibited bacterial growth, and thus, biofilm formation without the addition of antibiotic drug. The inhibitory dosages of iron oxide NPs were investigated and the minimum inhibitory concentrations are presented. These findings suggest that NP-drug conjugates may overcome the antibiotic drug resistance common in P. aeruginosa infections.

  5. Melatonin not only restores but also prevents the inhibition of the intestinal Ca(2+) absorption caused by glutathione depleting drugs.

    PubMed

    Areco, Vanessa; Rodriguez, Valeria; Marchionatti, Ana; Carpentieri, Agata; Tolosa de Talamoni, Nori

    2016-07-01

    We have previously demonstrated that melatonin (MEL) blocks the inhibition of the intestinal Ca(2+) absorption caused by menadione (MEN). The purpose of this study were to determine whether MEL not only restores but also prevents the intestinal Ca(2+) absorption inhibited either by MEN or BSO, two drugs that deplete glutathione (GSH) in different ways, and to analyze the mechanisms by which MEN and MEL alter the movement of Ca(2+) across the duodenum. To know this, chicks were divided into four groups: 1) controls, 2) MEN treated, 3) MEL treated, and 4) treated sequentially with MEN and MEL or with MEN and MEL at the same time. In a set of experiments, chicks treated with BSO or sequentially with BSO and MEL or with BSO and MEL at the same time were used. MEL not only restored but also prevented the inhibition of the chick intestinal Ca(2+) absorption produced by either MEN or BSO. MEN altered the protein expression of molecules involved in the transcellular as well as in the paracellular pathway of the intestinal Ca(2+) absorption. MEL restored partially both pathways through normalization of the O2(-) levels. The nitrergic system was not altered by any treatment. In conclusion, MEL prevents or restores the inhibition of the intestinal Ca(2+) absorption caused by different GSH depleting drugs. It might become one drug for the treatment of intestinal Ca(2+) absorption under oxidant conditions having the advantage of low or null side effects. PMID:26970583

  6. Most drugs that reverse multidrug resistance also inhibit photoaffinity labeling of P-glycoprotein by a vinblastine analog

    SciTech Connect

    Akiyama, S.; Cornwell, M.M.; Kuwano, M.; Pastan, I.; Gottesman, M.M.

    1988-02-01

    Multidrug-resistant human KB carcinoma cells express a 170,000-dalton membrane glycoprotein (P-glycoprotein) that can be photoaffinity labeled with the vinblastine analog N-(p-azido-(3-/sup 125/I)salicyl)-N'-(beta-aminoethyl)vindesine. Several agents that suppress the multidrug-resistant phenotype, including N-solanesyl-N,N'-bis(3,4-dimethylbenzyl)ethylenediamine, cepharanthine, quinidine, and reserpine, were found to inhibit photolabeling of P-glycoprotein at doses comparable to those that reverse multidrug resistance. However, the phenothiazines chlorpromazine and trifluoperazine, which also effectively reverse multidrug resistance, were poor inhibitors of the photoaffinity labeling of P-glycoprotein. Chloroquine, propranolol, or atropine, which only partially reversed the drug resistance, also did not inhibit photolabeling. Naphthalene sulfonamide calmodulin inhibitors, W7 and W5, as well as many other drugs that did not circumvent multidrug resistance, did not inhibit photolabeling. These studies suggest that most, but not all, agents that phenotypically suppress multidrug resistance also inhibit drug binding to a site on P-glycoprotein with which a photoaffinity analog of vinblastine interacts.

  7. Vandetanib inhibits both VEGFR-2 and EGFR signalling at clinically relevant drug levels in preclinical models of human cancer.

    PubMed

    Brave, Sandra R; Odedra, Rajesh; James, Neil H; Smith, Neil R; Marshall, Gayle B; Acheson, Kerry L; Baker, Dawn; Howard, Zoe; Jackson, Lynsay; Ratcliffe, Kirsty; Wainwright, Anna; Lovick, Susan C; Hickinson, D Mark; Wilkinson, Robert W; Barry, Simon T; Speake, Georgina; Ryan, Anderson J

    2011-07-01

    Vandetanib is a multi-targeted receptor tyrosine kinase inhibitor that is in clinical development for the treatment of solid tumours. This preclinical study examined the inhibition of two key signalling pathways (VEGFR-2, EGFR) at drug concentrations similar to those achieved in the clinic, and their contribution to direct and indirect antitumour effects of vandetanib. For in vitro studies, receptor phosphorylation was assessed by Western blotting and ELISA, cell proliferation was assessed using a cell viability endpoint, and effects on cell cycle determined using flow cytometry. For in vivo studies, Western blotting, ELISA and immunohistochemistry (IHC) were used to assess receptor phosphorylation. Cell culture experiments demonstrated that anti-proliferative effects of vandetanib resulted from inhibition of either EGFR or VEGFR-2 signalling in endothelial cells, but were associated with inhibition of EGFR signalling in tumour cells. Vandetanib inhibited both EGFR and VEGFR-2 signalling in normal lung tissue and in tumour xenografts. In a lung cancer model expressing an activating EGFR mutation, the activity of vandetanib was similar to that of a highly selective EGFR inhibitor (gefitinib), and markedly greater than that of a highly selective VEGFR inhibitor (vatalanib). These data suggest that at the plasma exposures achieved in the clinic, vandetanib will significantly inhibit both VEGFR-2 and EGFR signalling, and that both inhibition of angiogenesis and direct inhibition of tumour cell growth can contribute to treatment response. PMID:21537841

  8. Mutually unbiased bases

    NASA Astrophysics Data System (ADS)

    Chaturvedi, S.

    2002-08-01

    After a brief review of the notion of a full set of mutually unbiased bases in an N-dimensional Hilbert space, we summarize the work of Wootters and Fields (W K Wootters and B C Fields, Ann. Phys. 191, 363 (1989)) which gives an explicit construction for such bases for the case N=pr, where p is a prime. Further, we show how, by exploiting certain freedom in the Wootters-Fields construction, the task of explicitly writing down such bases can be simplified for the case when p is an odd prime. In particular, we express the results entirely in terms of the character vectors of the cyclic group G of order p. We also analyse the connection between mutually unbiased bases and the representations of G.

  9. Drug-protein hydrogen bonds govern the inhibition of the ATP hydrolysis of the multidrug transporter P-glycoprotein.

    PubMed

    Chufan, Eduardo E; Kapoor, Khyati; Ambudkar, Suresh V

    2016-02-01

    P-glycoprotein (P-gp) is a member of the ATP-binding cassette transporter superfamily. This multidrug transporter utilizes energy from ATP hydrolysis for the efflux of a variety of hydrophobic and amphipathic compounds including anticancer drugs. Most of the substrates and modulators of P-gp stimulate its basal ATPase activity, although some inhibit it. The molecular mechanisms that are in play in either case are unknown. In this report, mutagenesis and molecular modeling studies of P-gp led to the identification of a pair of phenylalanine-tyrosine structural motifs in the transmembrane region that mediate the inhibition of ATP hydrolysis by certain drugs (zosuquidar, elacridar and tariquidar), with high affinity (IC50's ranging from 10 to 30nM). Upon mutation of any of these residues, drugs that inhibit the ATPase activity of P-gp switch to stimulation of the activity. Molecular modeling revealed that the phenylalanine residues F978 and F728 interact with tyrosine residues Y953 and Y310, respectively, in an edge-to-face conformation, which orients the tyrosines in such a way that they establish hydrogen-bond contacts with the inhibitor. Biochemical investigations along with transport studies in intact cells showed that the inhibitors bind at a high affinity site to produce inhibition of ATP hydrolysis and transport function. Upon mutation, they bind at lower affinity sites, stimulating ATP hydrolysis and only poorly inhibiting transport. These results also reveal that screening chemical compounds for their ability to inhibit the basal ATP hydrolysis can be a reliable tool to identify modulators with high affinity for P-gp. PMID:26686578

  10. Anti-addiction drug ibogaine inhibits voltage-gated ionic currents: A study to assess the drug's cardiac ion channel profile

    SciTech Connect

    Koenig, Xaver; Kovar, Michael; Rubi, Lena; Mike, Agnes K.; Lukacs, Peter; Gawali, Vaibhavkumar S.; Todt, Hannes; Hilber, Karlheinz; Sandtner, Walter

    2013-12-01

    The plant alkaloid ibogaine has promising anti-addictive properties. Albeit not licenced as a therapeutic drug, and despite hints that ibogaine may perturb the heart rhythm, this alkaloid is used to treat drug addicts. We have recently reported that ibogaine inhibits human ERG (hERG) potassium channels at concentrations similar to the drugs affinity for several of its known brain targets. Thereby the drug may disturb the heart's electrophysiology. Here, to assess the drug's cardiac ion channel profile in more detail, we studied the effects of ibogaine and its congener 18-Methoxycoronaridine (18-MC) on various cardiac voltage-gated ion channels. We confirmed that heterologously expressed hERG currents are reduced by ibogaine in low micromolar concentrations. Moreover, at higher concentrations, the drug also reduced human Na{sub v}1.5 sodium and Ca{sub v}1.2 calcium currents. Ion currents were as well reduced by 18-MC, yet with diminished potency. Unexpectedly, although blocking hERG channels, ibogaine did not prolong the action potential (AP) in guinea pig cardiomyocytes at low micromolar concentrations. Higher concentrations (≥ 10 μM) even shortened the AP. These findings can be explained by the drug's calcium channel inhibition, which counteracts the AP-prolonging effect generated by hERG blockade. Implementation of ibogaine's inhibitory effects on human ion channels in a computer model of a ventricular cardiomyocyte, on the other hand, suggested that ibogaine does prolong the AP in the human heart. We conclude that therapeutic concentrations of ibogaine have the propensity to prolong the QT interval of the electrocardiogram in humans. In some cases this may lead to cardiac arrhythmias. - Highlights: • We study effects of anti-addiction drug ibogaine on ionic currents in cardiomyocytes. • We assess the cardiac ion channel profile of ibogaine. • Ibogaine inhibits hERG potassium, sodium and calcium channels. • Ibogaine’s effects on ion channels are a

  11. Azvudine, a novel nucleoside reverse transcriptase inhibitor showed good drug combination features and better inhibition on drug-resistant strains than lamivudine in vitro.

    PubMed

    Wang, Rui-Rui; Yang, Qing-Hua; Luo, Rong-Hua; Peng, You-Mei; Dai, Shao-Xing; Zhang, Xing-Jie; Chen, Huan; Cui, Xue-Qing; Liu, Ya-Juan; Huang, Jing-Fei; Chang, Jun-Biao; Zheng, Yong-Tang

    2014-01-01

    Azvudine is a novel nucleoside reverse transcriptase inhibitor with antiviral activity on human immunodeficiency virus, hepatitis B virus and hepatitis C virus. Here we reported the in vitro activity of azvudine against HIV-1 and HIV-2 when used alone or in combination with other antiretroviral drugs and its drug resistance features. Azvudine exerted highly potent inhibition on HIV-1 (EC(50)s ranging from 0.03 to 6.92 nM) and HIV-2 (EC(50)s ranging from 0.018 to 0.025 nM). It also showed synergism in combination with six approved anti-HIV drugs on both C8166 and PBMC. In combination assay, the concentrations of azvudine used were 1000 or 500 fold lower than other drugs. Azvudine also showed potent inhibition on NRTI-resistant strains (L74V and T69N). Although M184V caused 250 fold reduction in susceptibility, azvudine remained active at nanomolar range. In in vitro induced resistant assay, the frequency of M184I mutation increased with induction time which suggests M184I as the key mutation in azvudine treatment. As control, lamivudine treatment resulted in a higher frequency of M184I/V given the same induction time and higher occurrence of M184V was found. Molecular modeling analysis suggests that steric hindrance is more pronounced in mutant M184I than M184V due to the azido group of azvudine. The present data demonstrates the potential of azvudine as a complementary drug to current anti-HIV drugs. M184I should be the key mutation, however, azvudine still remains active on HIV-1LAI-M184V at nanomolar range. PMID:25144636

  12. Small molecule inhibition of CBP/catenin interactions eliminates drug resistant clones in acute lymphoblastic leukemia

    PubMed Central

    Gang, Eun Ji; Hsieh, Yao-Te; Pham, Jennifer; Zhao, Yi; Nguyen, Cu; Huantes, Sandra; Park, Eugene; Naing, Khatija; Klemm, Lars; Swaminathan, Srividya; Conway, Edward M.; Pelus, Louis M.; Crispino, John; Mullighan, Charles; McMillan, Michael; Müschen, Markus; Kahn, Michael; Kim, Yong-Mi

    2014-01-01

    Drug resistance in acute lymphoblastic leukemia (ALL) remains a major problem warranting new treatment strategies. Wnt/catenin signaling is critical for the self-renewal of normal hematopoietic progenitor cells. Deregulated Wnt signaling is evident in chronic and acute myeloid leukemia, however little is known about ALL. Differential interaction of catenin with either the Kat3 coactivator CREBBP (CBP) or the highly homologous EP300 (p300) is critical to determine divergent cellular responses and provides a rationale for the regulation of both proliferation and differentiation by the Wnt signaling pathway. Usage of the coactivator CBP by catenin leads to transcriptional activation of cassettes of genes that are involved in maintenance of progenitor cell self-renewal. However, the use of the coactivator p300, leads to activation of genes involved in the initiation of differentiation. ICG-001 is a novel small molecule modulator of Wnt/catenin signaling, which specifically binds to the N-terminus of CBP and not p300, within amino acids 1–110, thereby disrupting the interaction between CBP and catenin. Here, we report that selective disruption of the CBP/β- and γ-catenin interactions using ICG-001 leads to differentiation of pre-B ALL cells and loss of self-renewal capacity. Survivin, an inhibitor-of-apoptosis protein, was also downregulated in primary ALL after treatment with ICG-001. Using ChIP assay, we demonstrate occupancy by CBP of the survivin promoter, which is decreased by ICG-001 in primary ALL. CBP-mutations have been recently identified in a significant percentage of ALL patients, however, almost all of the identified mutations reported occur C-terminal to the binding site for ICG-001. Importantly, ICG-001, regardless of CBP mutational status and chromosomal aberration, leads to eradication of drug-resistant primary leukemia in combination with conventional therapy in vitro and significantly prolongs the survival of NOD/SCID mice engrafted with primary

  13. Synergistic Effect of Cold Atmospheric Plasma and Drug Loaded Core-shell Nanoparticles on Inhibiting Breast Cancer Cell Growth

    PubMed Central

    Zhu, Wei; Lee, Se-Jun; Castro, Nathan J.; Yan, Dayun; Keidar, Michael; Zhang, Lijie Grace

    2016-01-01

    Nano-based drug delivery devices allowing for effective and sustained targeted delivery of therapeutic agents to solid tumors have revolutionized cancer treatment. As an emerging biomedical technique, cold atmospheric plasma (CAP), an ionized non-thermal gas mixture composed of various reactive oxygen species, reactive nitrogen species, and UV photons, shows great potential for cancer treatment. Here we seek to develop a new dual cancer therapeutic method by integrating promising CAP and novel drug loaded core-shell nanoparticles and evaluate its underlying mechanism for targeted breast cancer treatment. For this purpose, core-shell nanoparticles were synthesized via co-axial electrospraying. Biocompatible poly (lactic-co-glycolic acid) was selected as the polymer shell to encapsulate anti-cancer therapeutics. Results demonstrated uniform size distribution and high drug encapsulation efficacy of the electrosprayed nanoparticles. Cell studies demonstrated the effectiveness of drug loaded nanoparticles and CAP for synergistic inhibition of breast cancer cell growth when compared to each treatment separately. Importantly, we found CAP induced down-regulation of metastasis related gene expression (VEGF, MTDH, MMP9, and MMP2) as well as facilitated drug loaded nanoparticle uptake which may aid in minimizing drug resistance-a major problem in chemotherapy. Thus, the integration of CAP and drug encapsulated nanoparticles provides a promising tool for the development of a new cancer treatment strategy. PMID:26917087

  14. Synergistic Effect of Cold Atmospheric Plasma and Drug Loaded Core-shell Nanoparticles on Inhibiting Breast Cancer Cell Growth.

    PubMed

    Zhu, Wei; Lee, Se-Jun; Castro, Nathan J; Yan, Dayun; Keidar, Michael; Zhang, Lijie Grace

    2016-01-01

    Nano-based drug delivery devices allowing for effective and sustained targeted delivery of therapeutic agents to solid tumors have revolutionized cancer treatment. As an emerging biomedical technique, cold atmospheric plasma (CAP), an ionized non-thermal gas mixture composed of various reactive oxygen species, reactive nitrogen species, and UV photons, shows great potential for cancer treatment. Here we seek to develop a new dual cancer therapeutic method by integrating promising CAP and novel drug loaded core-shell nanoparticles and evaluate its underlying mechanism for targeted breast cancer treatment. For this purpose, core-shell nanoparticles were synthesized via co-axial electrospraying. Biocompatible poly (lactic-co-glycolic acid) was selected as the polymer shell to encapsulate anti-cancer therapeutics. Results demonstrated uniform size distribution and high drug encapsulation efficacy of the electrosprayed nanoparticles. Cell studies demonstrated the effectiveness of drug loaded nanoparticles and CAP for synergistic inhibition of breast cancer cell growth when compared to each treatment separately. Importantly, we found CAP induced down-regulation of metastasis related gene expression (VEGF, MTDH, MMP9, and MMP2) as well as facilitated drug loaded nanoparticle uptake which may aid in minimizing drug resistance-a major problem in chemotherapy. Thus, the integration of CAP and drug encapsulated nanoparticles provides a promising tool for the development of a new cancer treatment strategy. PMID:26917087

  15. VX-509 (Decernotinib)-Mediated CYP3A Time-Dependent Inhibition: An Aldehyde Oxidase Metabolite as a Perpetrator of Drug-Drug Interactions.

    PubMed

    Zetterberg, Craig; Maltais, Francois; Laitinen, Leena; Liao, Shengkai; Tsao, Hong; Chakilam, Ananthsrinivas; Hariparsad, Niresh

    2016-08-01

    (R)-2-((2-(1H-pyrrolo[2,3-b]pyridin-3-yl)pyrimidin-4-yl)amino)-2-methyl-N-(2,2,2-trifluoroethyl)butanamide (VX-509, decernotinib) is an oral Janus kinase 3 inhibitor that has been studied in patients with rheumatoid arthritis. Patients with rheumatoid arthritis often receive multiple medications, such as statins and steroids, to manage the signs and symptoms of comorbidities, which increases the chances of drug-drug interactions (DDIs). Mechanism-based inhibition is a subset of time-dependent inhibition (TDI) and occurs when a molecule forms a reactive metabolite which irreversibly binds and inactivates drug-metabolizing enzymes, potentially increasing the systemic load to toxic concentrations. Traditionally, perpetrating compounds are screened using human liver microsomes (HLMs); however, this system may be inadequate when the precipitant is activated by a non-cytochrome P450 (P450)-mediated pathway. Even though studies assessing competitive inhibition and TDI using HLM suggested a low risk for CYP3A4-mediated DDI in the clinic, VX-509 increased the area under the curve of midazolam, atorvastatin, and methyl-prednisolone by approximately 12.0-, 2.7-, and 4.3-fold, respectively. Metabolite identification studies using human liver cytosol indicated that VX-509 is converted to an oxidative metabolite, which is the perpetrator of the DDIs observed in the clinic. As opposed to HLM, hepatocytes contain the full complement of drug-metabolizing enzymes and transporters and can be used to assess TDI arising from non-P450-mediated metabolic pathways. In the current study, we highlight the role of aldehyde oxidase in the formation of the hydroxyl-metabolite of VX-509, which is involved in clinically significant TDI-based DDIs and represents an additional example in which a system-dependent prediction of TDI would be evident. PMID:27298338

  16. Differential involvement of 5-HT projections within the amygdala in prepulse inhibition but not in psychotomimetic drug-induced hyperlocomotion.

    PubMed

    Kusljic, Snezana; van den Buuse, Maarten

    2006-03-15

    While there is abundant evidence for a role of 5-HT and the amygdala in anxiety and depression, the role of 5-HT in this brain region in schizophrenia is less well understood. We therefore examined the effects of local 5-HT depletion in the amygdala on psychotomimetic drug-induced locomotor hyperactivity and prepulse inhibition, two animal model of aspects of schizophrenia. Pentobarbital-anaesthetized (60 mg/kg, i.p.) male Sprague-Dawley rats were stereotaxically micro-injected with 0.5 microl of a 5 microg/mul solution of the 5-HT neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) into either the basolateral (BLA) or central nucleus of amygdala (CeN). Two weeks after the surgery, rats with BLA lesions did not show changes in either psychotomimetic drug-induced locomotor hyperactivity or prepulse inhibition. In contrast, rats with CeN lesions showed significant disruption of prepulse inhibition, but no changes in psychotomimetic drug-induced locomotor hyperactivity. Neurochemical analysis and autoradiographic labelling of 5-HT transporter sites showed that a good degree of anatomical selectivity was obtained. Following administration of 5,7-DHT into the amygdala, the concentration of 5-HT was significantly reduced. Similarly, 5-HT transporter autoradiographs showed differential and selective lesions of 5-HT innervation in targeted subregions of the amygdala. These results provide evidence for differential involvement of 5-HT projections within the amygdala in prepulse inhibition but not locomotor hyperactivity. Thus, the present study supports the view that 5-HT in the amygdala may be involved in aspects of schizophrenia and a target for antipsychotic drug action. PMID:16303186

  17. EGFR inhibition evokes innate drug resistance in lung cancer cells by preventing Akt activity and thus inactivating Ets-1 function.

    PubMed

    Phuchareon, Janyaporn; McCormick, Frank; Eisele, David W; Tetsu, Osamu

    2015-07-21

    Nonsmall cell lung cancer (NSCLC) is the leading cause of cancer death worldwide. About 14% of NSCLCs harbor mutations in epidermal growth factor receptor (EGFR). Despite remarkable progress in treatment with tyrosine kinase inhibitors (TKIs), only 5% of patients achieve tumor reduction >90%. The limited primary responses are attributed partly to drug resistance inherent in the tumor cells before therapy begins. Recent reports showed that activation of receptor tyrosine kinases (RTKs) is an important determinant of this innate drug resistance. In contrast, we demonstrate that EGFR inhibition promotes innate drug resistance despite blockade of RTK activity in NSCLC cells. EGFR TKIs decrease both the mitogen-activated protein kinase (MAPK) and Akt protein kinase pathways for a short time, after which the Ras/MAPK pathway becomes reactivated. Akt inhibition selectively blocks the transcriptional activation of Ets-1, which inhibits its target gene, dual specificity phosphatase 6 (DUSP6), a negative regulator specific for ERK1/2. As a result, ERK1/2 is activated. Furthermore, elevated c-Src stimulates Ras GTP-loading and activates Raf and MEK kinases. These observations suggest that not only ERK1/2 but also Akt activity is essential to maintain Ets-1 in an active state. Therefore, despite high levels of ERK1/2, Ets-1 target genes including DUSP6 and cyclins D1, D3, and E2 remain suppressed by Akt inhibition. Reduction of DUSP6 in combination with elevated c-Src renews activation of the Ras/MAPK pathway, which enhances cell survival by accelerating Bim protein turnover. Thus, EGFR TKIs evoke innate drug resistance by preventing Akt activity and inactivating Ets-1 function in NSCLC cells. PMID:26150526

  18. EGFR inhibition evokes innate drug resistance in lung cancer cells by preventing Akt activity and thus inactivating Ets-1 function

    PubMed Central

    Phuchareon, Janyaporn; McCormick, Frank; Eisele, David W.; Tetsu, Osamu

    2015-01-01

    Nonsmall cell lung cancer (NSCLC) is the leading cause of cancer death worldwide. About 14% of NSCLCs harbor mutations in epidermal growth factor receptor (EGFR). Despite remarkable progress in treatment with tyrosine kinase inhibitors (TKIs), only 5% of patients achieve tumor reduction >90%. The limited primary responses are attributed partly to drug resistance inherent in the tumor cells before therapy begins. Recent reports showed that activation of receptor tyrosine kinases (RTKs) is an important determinant of this innate drug resistance. In contrast, we demonstrate that EGFR inhibition promotes innate drug resistance despite blockade of RTK activity in NSCLC cells. EGFR TKIs decrease both the mitogen-activated protein kinase (MAPK) and Akt protein kinase pathways for a short time, after which the Ras/MAPK pathway becomes reactivated. Akt inhibition selectively blocks the transcriptional activation of Ets-1, which inhibits its target gene, dual specificity phosphatase 6 (DUSP6), a negative regulator specific for ERK1/2. As a result, ERK1/2 is activated. Furthermore, elevated c-Src stimulates Ras GTP-loading and activates Raf and MEK kinases. These observations suggest that not only ERK1/2 but also Akt activity is essential to maintain Ets-1 in an active state. Therefore, despite high levels of ERK1/2, Ets-1 target genes including DUSP6 and cyclins D1, D3, and E2 remain suppressed by Akt inhibition. Reduction of DUSP6 in combination with elevated c-Src renews activation of the Ras/MAPK pathway, which enhances cell survival by accelerating Bim protein turnover. Thus, EGFR TKIs evoke innate drug resistance by preventing Akt activity and inactivating Ets-1 function in NSCLC cells. PMID:26150526

  19. Vitamin D Enhances the Efficacy of Irinotecan through miR-627-Mediated Inhibition of Intratumoral Drug Metabolism.

    PubMed

    Sun, Meiyan; Zhang, Qunshu; Yang, Xiaoyu; Qian, Steven Y; Guo, Bin

    2016-09-01

    Cytochrome P450 enzyme CYP3A4 is an important drug-metabolizing enzyme, and high levels of tumoral expression of CYP3A4 are linked to drug resistance. We investigated the function of vitamin D-regulated miR-627 in intratumoral CYP3A4 suppression and its role in enhancing the efficacy of chemotherapy. We found that miR-627 targets CYP3A4 and suppresses CYP3A4 expression in colon cancer cell lines. Furthermore, calcitriol (the active form of vitamin D) suppressed CYP3A4 expression by activating miR-627. As a result, calcitriol inhibited CYP3A4-mediated metabolism of irinotecan (a topoisomerase I inhibitor) in cancer cells. We show that calcitriol enhanced the efficacy of irinotecan in growth inhibition and apoptosis induction. When miR-627 is inhibited, calcitriol fails to enhance the activity of irinotecan. In addition, overexpression of miR-627 or siRNA knockdown of CYP3A4 enhanced the efficacy of irinotecan in growth inhibition and apoptosis induction. In contrast, overexpression of CYP3A4 abolished the effects of calcitriol on the activity of irinotecan. Using a nude mouse xenograft model, we demonstrated that calcitriol inhibited CYP3A4 and enhanced the in vivo antitumor activity of irinotecan without causing side effects. Our study identified a novel target for improving cancer therapy, i.e., modulating the intratumoral CYP3A4-mediated drug metabolism with vitamin D. This strategy could enhance the therapeutic efficacy without eliciting the side effects. Mol Cancer Ther; 15(9); 2086-95. ©2016 AACR. PMID:27458137

  20. In vitro inhibition of drug-resistant and drug-sensitive strains of Mycobacterium tuberculosis by ethnobotanically selected South African plants.

    PubMed

    Lall, N; Meyer, J J

    1999-09-01

    Twenty South African medicinal plants used to treat pulmonary diseases were screened for activity against drug-resistant and drug-sensitive strains of Mycobacterium tuberculosis. A preliminary screening of acetone and water plant extracts against a drug-sensitive strain of Mycobacterium tuberculosis, H37Rv, was done by the agar plate method. Fourteen of the 20 acetone extracts showed inhibitory activity at a concentration of 0.5 mg/ml against this strain. Acetone as well as water extracts of Cryptocarya latifolia, Euclea natalensis, Helichrysum melanacme, Nidorella anomala and Thymus vulgaris inhibited the growth of M. tuberculosis. Given the activity of 14 acetone extracts at 0.5 mg/ml against the drug-sensitive strain by the agar plate method, a further study was done employing a rapid radiometric method to confirm the inhibitory activity. These active acetone extracts were screened against the H37Rv strain as well as a strain resistant to the drugs isoniazid and rifampin. The minimal inhibitory concentration of Croton pseudopulchellus, Ekebergia capensis, Euclea natalensis, Nidorella anomala and Polygala myrtifolia was 0.1 mg/ml against the H37Rv strain by the radiometric method. Extracts of Chenopodium ambrosioides, Ekebergia capensis, Euclea natalensis, Helichrysum melanacme, Nidorella anomala and Polygala myrtifolia were active against the resistant strain at 0.1 mg/ml. Eight plants showed activity against both strains at a concentration of 1.0 mg/ml. PMID:10473184

  1. Nanoparticles inhibit cancer cell invasion and enhance antitumor efficiency by targeted drug delivery via cell surface-related GRP78.

    PubMed

    Zhao, Liang; Li, Hongdan; Shi, Yijie; Wang, Guan; Liu, Liwei; Su, Chang; Su, Rongjian

    2015-01-01

    Nanoparticles (NPs) which target specific agents could effectively recognize the target cells and increase the stability of chemical agents by encapsulation. As such, NPs have been widely used in cancer treatment research. Recently, over 90% of treatment failure cases in patients with metastatic cancer were attributed to resistance to chemotherapy. Surface-exposed glucose-regulated protein of 78 kDa (GRP78) is expressed highly on many tumor cell surfaces in many human cancers and is related to the regulation of invasion and metastasis. Herein, we report that NPs conjugated with antibody against GRP78 (mAb GRP78-NPs) inhibit the adhesion, invasion, and metastasis of hepatocellular carcinoma (HCC) and promote drug delivery of 5-fluorouracil into GRP78 high-expressed human hepatocellular carcinoma cells. Our new findings suggest that mAb GRP78-NPs could enhance drug accumulation by effectively transporting NPs into cell surface GRP78-overexpressed human hepatocellular carcinoma cells and then inhibit cell proliferation and viability and induce cell apoptosis by regulating caspase-3. In brief, mAb GRP78-NPs effectively inhibit cancer cell invasion and enhance antitumor efficiency by targeted drug delivery. PMID:25565817

  2. Nanoparticles inhibit cancer cell invasion and enhance antitumor efficiency by targeted drug delivery via cell surface-related GRP78

    PubMed Central

    Zhao, Liang; Li, Hongdan; Shi, Yijie; Wang, Guan; Liu, Liwei; Su, Chang; Su, Rongjian

    2015-01-01

    Nanoparticles (NPs) which target specific agents could effectively recognize the target cells and increase the stability of chemical agents by encapsulation. As such, NPs have been widely used in cancer treatment research. Recently, over 90% of treatment failure cases in patients with metastatic cancer were attributed to resistance to chemotherapy. Surface-exposed glucose-regulated protein of 78 kDa (GRP78) is expressed highly on many tumor cell surfaces in many human cancers and is related to the regulation of invasion and metastasis. Herein, we report that NPs conjugated with antibody against GRP78 (mAb GRP78-NPs) inhibit the adhesion, invasion, and metastasis of hepatocellular carcinoma (HCC) and promote drug delivery of 5-fluorouracil into GRP78 high-expressed human hepatocellular carcinoma cells. Our new findings suggest that mAb GRP78-NPs could enhance drug accumulation by effectively transporting NPs into cell surface GRP78-overexpressed human hepatocellular carcinoma cells and then inhibit cell proliferation and viability and induce cell apoptosis by regulating caspase-3. In brief, mAb GRP78-NPs effectively inhibit cancer cell invasion and enhance antitumor efficiency by targeted drug delivery. PMID:25565817

  3. Inhibition of Human Immunodeficiency Virus and Growth of Infected T Cells by the Immunosuppressive Drugs Cyclosporin A and FK 506

    NASA Astrophysics Data System (ADS)

    Karpas, Abraham; Lowdell, Mark; Jacobson, S. Kim; Hill, Fergal

    1992-09-01

    The effects of the immunosuppressive drugs cyclosporin A and FK 506 were studied on cells chronically infected with human immunodeficiency virus type 1 (HIV-1) as well as on uninfected and newly infected cells. When cells chronically infected with HIV-1 or with HIV-2 were cocultivated with uninfected cells in the presence of cyclosporin A or FK 506 there was a delay in the formation of syncytia and of cytopathic effects. This inhibitory effect was not due to decreased membrane expression of CD4. In addition, there was an ≈100-fold reduction in the yield of infectious HIV-1 when the infected cells were grown in the presence of these drugs, a finding consistent with other evidence of decreased HIV expression. Both drugs were found to inhibit the growth of chronically infected cells at concentrations that did not inhibit the growth of the uninfected cells. These results, demonstrating that cyclosporin A and FK 506 interfere with HIV production and selectively inhibit the growth of infected cells, suggest that they may be useful in the treatment of this infection and indicate further cellular targets for antiviral agents.

  4. Risk Factors for Development of Cholestatic Drug-Induced Liver Injury: Inhibition of Hepatic Basolateral Bile Acid Transporters Multidrug Resistance-Associated Proteins 3 and 4

    PubMed Central

    Köck, Kathleen; Ferslew, Brian C.; Netterberg, Ida; Yang, Kyunghee; Urban, Thomas J.; Swaan, Peter W.; Stewart, Paul W.

    2014-01-01

    Impaired hepatic bile acid export may contribute to development of cholestatic drug-induced liver injury (DILI). The multidrug resistance-associated proteins (MRP) 3 and 4 are postulated to be compensatory hepatic basolateral bile acid efflux transporters when biliary excretion by the bile salt export pump (BSEP) is impaired. BSEP inhibition is a risk factor for cholestatic DILI. This study aimed to characterize the relationship between MRP3, MRP4, and BSEP inhibition and cholestatic potential of drugs. The inhibitory effect of 88 drugs (100 μM) on MRP3- and MRP4-mediated substrate transport was measured in membrane vesicles. Drugs selected for investigation included 50 BSEP non-inhibitors (24 non-cholestatic; 26 cholestatic) and 38 BSEP inhibitors (16 non-cholestatic; 22 cholestatic). MRP4 inhibition was associated with an increased risk of cholestatic potential among BSEP non-inhibitors. In this group, for each 1% increase in MRP4 inhibition, the odds of the drug being cholestatic increased by 3.1%. Using an inhibition cutoff of 21%, which predicted a 50% chance of cholestasis, 62% of cholestatic drugs inhibited MRP4 (P < 0.05); in contrast, only 17% of non-cholestatic drugs were MRP4 inhibitors. Among BSEP inhibitors, MRP4 inhibition did not provide additional predictive value of cholestatic potential; almost all BSEP inhibitors were also MRP4 inhibitors. Inclusion of pharmacokinetic predictor variables (e.g., maximal unbound concentration in plasma) in addition to percent MRP4 inhibition in logistic regression models did not improve cholestasis prediction. Association of cholestasis with percent MRP3 inhibition was not statistically significant, regardless of BSEP-inhibition status. Inhibition of MRP4, in addition to BSEP, may be a risk factor for the development of cholestatic DILI. PMID:24154606

  5. A retrospective drug use evaluation of cabergoline for lactation inhibition at a tertiary care teaching hospital in Qatar

    PubMed Central

    AlSaad, Doua; ElSalem, Samah; Abdulrouf, Palli Valapila; Thomas, Binny; Alsaad, Tayseer; Ahmed, Afif; AlHail, Moza

    2016-01-01

    Background Breastfeeding is considered as gold standard for infant nutrition and should be interrupted only when a compelling indication exists. Certain medical conditions such as abortion, stillbirth, HIV infection, or infant galactosemia and certain medications such as chemotherapy necessitate lactation inhibition to protect the health of mother and infant. Drug use evaluation (DUE) studies are done to explore the current practice in a setting and help to identify areas in which further information and education may be needed by clinicians. Objective The aim of this study was to conduct a DUE of cabergoline to assess indications for lactation inhibition, dosage regimen, and its safety. Method A retrospective cross-sectional DUE study was conducted over a period of 4 months from September 1, 2013, till December 31, 2013, at the Women’s Hospital, Qatar. All cabergoline prescriptions written for lactation inhibition within 10 days of delivery or abortion were included in the study. A descriptive data analysis was undertaken. Results Of the 85 patients included, stillbirth (50.6%) was considered as the main reason for lactation inhibition, followed by abortion (27.1%) and neonatal death (12.9%). The remaining 9.4% of the patients had live baby, and the majority of them were prescribed cabergoline for lactation inhibition because their maternal medical conditions required the use of drugs with insufficient safety data (n=6). Seventy-four percent of patients received cabergoline at accurate time and dose. However, 14% of the patients had preexisting hypertensive disorder and 58.3% of them were diagnosed as uncontrolled hypertension. Conclusion The current DUE study found that cabergoline was mainly used to inhibit lactation for patients with stillbirth, abortion, and neonatal death. In mothers who use medications for other medical conditions, benefits and risks of breastfeeding should be carefully balanced before prescribing cabergoline. Current prescribing pattern

  6. Inhibition of FAAH and activation of PPAR: New approaches to the treatment of cognitive dysfunction and drug addiction

    PubMed Central

    Panlilio, Leigh V.; Justinova, Zuzana; Goldberg, Steven R.

    2013-01-01

    Enhancing the effects of endogenously-released cannabinoid ligands in the brain might provide therapeutic effects more safely and effectively than administering drugs that act directly at the cannabinoid receptor. Inhibitors of fatty acid amide hydrolase (FAAH) prevent the breakdown of endogenous ligands for cannabinoid receptors and peroxisome proliferator-activated receptors (PPAR), prolonging and enhancing the effects of these ligands when they are naturally released. This review considers recent research on the effects of FAAH inhibitors and PPAR activators in animal models of addiction and cognition (specifically learning and memory). These studies show that FAAH inhibitors can produce potentially therapeutic effects, some through cannabinoid receptors and some through PPAR. These effects include enhancing certain forms of learning, counteracting the rewarding effects of nicotine and alcohol, relieving symptoms of withdrawal from cannabis and other drugs, and protecting against relapse-like reinstatement of drug self-administration. Since FAAH inhibition might have a wide range of therapeutic actions but might also share some of the adverse effects of cannabis, it is noteworthy that at least one FAAH-inhibiting drug (URB597) has been found to have potentially beneficial effects but no indication of liability for abuse or dependence. Although these areas of research are new, the preliminary evidence indicates that they might lead to improved therapeutic interventions and a better understanding of the brain mechanisms underlying addiction and memory. PMID:23333350

  7. Inhibition of liver glutathione S-transferase activity in rats by hypolipidemic drugs related or unrelated to clofibrate.

    PubMed

    Foliot, A; Touchard, D; Mallet, L

    1986-05-15

    The effects of in vivo administration of six hypolipidemic drugs on rat liver glutathione S-transferase activity were compared. This activity was measured with sulfobromophthalein (BSP), 1,2-dichloro-4-nitrobenzene (DCNB) or 1-chloro-2,4-dinitrobenzene (CDNB) as substrate. Except for the nicotinic acid derivative ethanolamine oxiniacate, all the compounds tested significantly reduced it, whether or not they were related to clofibrate. The hepatic glutathione concentration either remained unchanged or only increased slightly after treatment with the various drugs. When measured, the maximal excretion rate of bile BSP dropped significantly, but not that of phenol-3,6-dibromophthalein (DBSP). Hepatic dye uptake and storage were not impaired. These results show that hypolipidemic drugs of the peroxisome proliferator type inhibit rat liver glutathione S-transferase activity and may reduce transport of anions conjugated with glutathione before excretion. PMID:3707598

  8. Inhibition of Major Drug Metabolizing CYPs by Common Herbal Medicines used by HIV/AIDS Patients in Africa– Implications for Herb-Drug Interactions

    PubMed Central

    Awortwe, Charles; Bouic, Patrick J.; Masimirembwa, Collen M.; Rosenkranz, Bernd

    2015-01-01

    The purpose of this study was to evaluate the potential risk of common herbal medicines used by HIV-infected patients in Africa for herb-drug interactions (HDI). High throughput screening assays consisting of recombinant Cytochrome P450 enzymes (CYPs) and fluorescent probes, and parallel artificial membrane permeability assays (PAMPA) were used. The potential of herbal medicines to cause HDI was ranked according to FDA guidelines for reversible inhibition and categorization of time dependent inhibition was based on the normalized ratio. CYPs 1A2 and 3A4 were most inhibited by the herbal extracts. H. hemerocallidea (IC50 = 0.63 μg/mL and 58 μg/mL) and E. purpurea (IC50 = 20 μg/mL and 12 μg/mL) were the potent inhibitors of CYPs 1A2 and 3A4 respectively. L. frutescens and H. hemerocallidea showed clear time dependent inhibition on CYP3A4. Furthermore, the inhibitory effect of both H. hemerocallidea and L. frutescens before and after PAMPA were identical. The results indicate potential HDI of H. hemerocallidea, L. frutescens and E. purpurea with substrates of the affected enzymes if maximum in vivo concentration is achieved. PMID:24475926

  9. Class I antiarrhythmic drugs inhibit human cardiac two-pore-domain K(+) (K2 ₂p) channels.

    PubMed

    Schmidt, Constanze; Wiedmann, Felix; Schweizer, Patrick A; Becker, Rüdiger; Katus, Hugo A; Thomas, Dierk

    2013-12-01

    Class IC antiarrhythmic drugs are commonly used for rhythm control in atrial fibrillation. In addition, class I drugs are administered to suppress ventricular tachyarrhythmia in selected cases. The multichannel blocking profile of class I compounds includes reduction of cardiac potassium currents in addition to their primary mechanism of action, sodium channel inhibition. Blockade of two-pore-domain potassium (K2P) channels in the heart causes action potential prolongation and may provide antiarrhythmic action in atrial fibrillation. This study was designed to elucidate inhibitory effects of class I antiarrhythmic drugs on K2P channels. Human K2P2.1 (TREK1) and hK2P3.1 (TASK1) channels were systematically tested for their sensitivity to clinically relevant class IA (ajmaline), class IB (mexiletine), and class IC (propafenone) antiarrhythmic compounds using whole-cell patch clamp and two-electrode voltage clamp electrophysiology in Chinese hamster ovary cells and in Xenopus oocytes. Mexiletine and propafenone inhibited hK2P2.1 (IC50,mexiletine=173µM; IC50,propafenone=7.6µM) and hK2P3.1 channels (IC50,mexiletine=97.3µM; IC50,propafenone=5.1µM) in mammalian cells. Ajmaline did not significantly reduce current amplitudes. K2P channels were blocked in open and closed states, resulting in resting membrane potential depolarization. Open rectification properties of the channels were not affected by class I drugs. In summary, class I antiarrhythmic drugs target cardiac K2P K(+) channels. Blockade of hK2P2.1 and hK2P3.1 potassium currents provides mechanistic evidence to establish cardiac K2P channels as antiarrhythmic drug targets. PMID:24070813

  10. Evaluation of possible inhibition of human liver drug metabolizing cytochromes P450 by two new acetylcholinesterase oxime-type reactivators.

    PubMed

    Spicakova, Alena; Anzenbacher, Pavel; Liskova, Barbora; Kuca, Kamil; Fusek, Josef; Anzenbacherova, Eva

    2016-02-01

    Two non-symmetric bispyridine oxime - based reactivators of acetylcholinesterase enzyme (AChE), labeled as K027 (1-(4-carbamoylpyridinium)-3-(4-hydroxyiminomethylpyridinium)-propane dibromide) and K203 ((E)-1-(4- carbamoylpyridinium)-4-(4-hydroxyiminomethylpyridinium)-but-2-ene dibromide) were tested for their potential to inhibit activities of human liver microsomal cytochromes P450 (CYP). Both oximes are very potent reactivators of organophosphate-inhibited AChE. An interaction of both compounds with CYP in human liver microsomal preparation was detected using difference spectroscopy. The compounds were shown to bind to CYP enzymes with spectral binding constants of 5.04 ± 1.79 nM (K027) and 5.2 ± 2.6 nM (K203). Enzymology studies were subsequently performed aimed at determining which of the nine most important CYP involved in drug is affected by this interaction. The results have shown no prominent inhibition of individual CYP activities with either compounds except in the case of CYP2E1 and K203. Diagnostic Dixon plot revealed that K203 acted as an uncompetitive inhibitor of CYP2E1. Inhibition of this activity however is not as prominent as to make a potent drug interaction likely. Hence, the interaction of K027 and K203 oxime-type AChE reactivators with human liver microsomal CYP enzymes does not seem to be of prominent clinical importance and both compounds could be safely used in this respect as antidotes with low risk of drug interactions. PMID:26747974

  11. Identification of approved drugs that inhibit the binding of amyloid β oligomers to ephrin type-B receptor 2.

    PubMed

    Suzuki, Koichiro; Aimi, Takahiro; Ishihara, Tomoaki; Mizushima, Tohru

    2016-05-01

    Ephrin type-B receptor 2 (EphB2) is a member of the receptor tyrosine kinase family and plays an important role in learning and memory functions. In patients with Alzheimer's disease (AD) and in mouse models of AD, a reduction in the hippocampal EphB2 level is observed. It was recently reported that normalization of the EphB2 level in the dentate gyrus rescues memory function in a mouse model of AD, suggesting that drugs that restore EphB2 levels may be beneficial in the treatment of AD. Amyloid β (Aβ) oligomers, which are believed to be key molecules involved in the pathogenesis of AD, induce EphB2 degradation through their direct binding to EphB2. Thus, compounds that inhibit the binding of Aβ oligomers to EphB2 may be beneficial. Here, we screened for such compounds from drugs already approved for clinical use in humans. Utilizing a cell-free screening assay, we determined that dihydroergotamine mesilate, bromocriptine mesilate, cepharanthine, and levonorgestrel inhibited the binding of Aβ oligomers to EphB2 but not to cellular prion protein, another endogenous receptor for Aβ oligomers. Additionally, these four compounds did not affect the binding between EphB2 and ephrinB2, an endogenous ligand for EphB2, suggesting that the compounds selectively inhibited the binding of Aβ oligomers to EphB2. This is the first identification of compounds that selectively inhibit the binding of Aβ oligomers to EphB2. These results suggest that these four compounds may be safe and effective drugs for treatment of AD. PMID:27419051

  12. Herb–drug interaction prediction based on the high specific inhibition of andrographolide derivatives towards UDP-glucuronosyltransferase (UGT) 2B7

    SciTech Connect

    Ma, Hai-Ying; Sun, Dong-Xue; Cao, Yun-Feng; Ai, Chun-Zhi; Qu, Yan-Qing; Hu, Cui-Min; Jiang, Changtao; Dong, Pei-Pei; Sun, Xiao-Yu; Hong, Mo; Tanaka, Naoki; Gonzalez, Frank J.; and others

    2014-05-15

    Herb–drug interaction strongly limits the clinical application of herbs and drugs, and the inhibition of herbal components towards important drug-metabolizing enzymes (DMEs) has been regarded as one of the most important reasons. The present study aims to investigate the inhibition potential of andrographolide derivatives towards one of the most important phase II DMEs UDP-glucuronosyltransferases (UGTs). Recombinant UGT isoforms (except UGT1A4)-catalyzed 4-methylumbelliferone (4-MU) glucuronidation reaction and UGT1A4-catalyzed trifluoperazine (TFP) glucuronidation were employed to firstly screen the andrographolide derivatives' inhibition potential. High specific inhibition of andrographolide derivatives towards UGT2B7 was observed. The inhibition type and parameters (K{sub i}) were determined for the compounds exhibiting strong inhibition capability towards UGT2B7, and human liver microsome (HLMs)-catalyzed zidovudine (AZT) glucuronidation probe reaction was used to furtherly confirm the inhibition behavior. In combination of inhibition parameters (K{sub i}) and in vivo concentration of andrographolide and dehydroandrographolide, the potential in vivo inhibition magnitude was predicted. Additionally, both the in vitro inhibition data and computational modeling results provide important information for the modification of andrographolide derivatives as selective inhibitors of UGT2B7. Taken together, data obtained from the present study indicated the potential herb–drug interaction between Andrographis paniculata and the drugs mainly undergoing UGT2B7-catalyzed metabolic elimination, and the andrographolide derivatives as potential candidates for the selective inhibitors of UGT2B7. - Highlights: • Specific inhibition of andrographolide derivatives towards UGT2B7. • Herb-drug interaction related withAndrographis paniculata. • Guidance for design of UGT2B7 specific inhibitors.

  13. Implementation of the mutual recognition agreement between the United States and the European Community; pharmaceutical GMP's and medical devices; establishment of a public docket and FDA contact points. Food and Drug Administration, HHS. Establishment of a public docket and FDA contact points.

    PubMed

    1999-03-01

    The Food and Drug Administration (FDA) is announcing the establishment of a public docket for the submission and public availability of information concerning the implementation of the Mutual Recognition Agreement (MRA) between the United States and the European Community (EC) in the areas of pharmaceutical good manufacturing practices (GMP's) and medical devices. FDA is also establishing contact points for information covering particular subjects under the MRA implementation, and the agency is making appropriate information available on the FDA web site. PMID:10557625

  14. Anti-addiction drug ibogaine inhibits hERG channels: a cardiac arrhythmia risk.

    PubMed

    Koenig, Xaver; Kovar, Michael; Boehm, Stefan; Sandtner, Walter; Hilber, Karlheinz

    2014-03-01

    Ibogaine, an alkaloid derived from the African shrub Tabernanthe iboga, has shown promising anti-addictive properties in animals. Anecdotal evidence suggests that ibogaine is also anti-addictive in humans. Thus, it alleviates drug craving and impedes relapse of drug use. Although not licensed as therapeutic drug, and despite evidence that ibogaine may disturb the rhythm of the heart, this alkaloid is currently used as an anti-addiction drug in alternative medicine. Here, we report that therapeutic concentrations of ibogaine reduce currents through human ether-a-go-go-related gene potassium channels. Thereby, we provide a mechanism by which ibogaine may generate life-threatening cardiac arrhythmias. PMID:22458604

  15. Cyclodextrin-Modified Porous Silicon Nanoparticles for Efficient Sustained Drug Delivery and Proliferation Inhibition of Breast Cancer Cells.

    PubMed

    Correia, Alexandra; Shahbazi, Mohammad-Ali; Mäkilä, Ermei; Almeida, Sérgio; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2015-10-21

    Over the past decade, the potential of polymeric structures has been investigated to overcome many limitations related to nanosized drug carriers by modulating their toxicity, cellular interactions, stability, and drug-release kinetics. In this study, we have developed a successful nanocomposite consisting of undecylenic acid modified thermally hydrocarbonized porous silicon nanoparticles (UnTHCPSi NPs) loaded with an anticancer drug, sorafenib, and surface-conjugated with heptakis(6-amino-6-deoxy)-β-cyclodextrin (HABCD) to show the impact of the surface polymeric functionalization on the physical and biological properties of the drug-loaded nanoparticles. Cytocompatibility studies showed that the UnTHCPSi-HABCD NPs were not toxic to breast cancer cells. HABCD also enhanced the suspensibility and both the colloidal and plasma stabilities of the UnTHCPSi NPs. UnTHCPSi-HABCD NPs showed a significantly increased interaction with breast cancer cells compared to bare NPs and also sustained the drug release. Furthermore, the sorafenib-loaded UnTHCPSi-HABCD NPs efficiently inhibited cell proliferation of the breast cancer cells. PMID:26440739

  16. Covariant mutually unbiased bases

    NASA Astrophysics Data System (ADS)

    Carmeli, Claudio; Schultz, Jussi; Toigo, Alessandro

    2016-06-01

    The connection between maximal sets of mutually unbiased bases (MUBs) in a prime-power dimensional Hilbert space and finite phase-space geometries is well known. In this article, we classify MUBs according to their degree of covariance with respect to the natural symmetries of a finite phase-space, which are the group of its affine symplectic transformations. We prove that there exist maximal sets of MUBs that are covariant with respect to the full group only in odd prime-power dimensional spaces, and in this case, their equivalence class is actually unique. Despite this limitation, we show that in dimension 2r covariance can still be achieved by restricting to proper subgroups of the symplectic group, that constitute the finite analogues of the oscillator group. For these subgroups, we explicitly construct the unitary operators yielding the covariance.

  17. Cancer drugs inhibit morphogenesis in the human fungal pathogen, Candida albicans.

    PubMed

    Routh, Madhushree M; Chauhan, Nitin M; Karuppayil, S Mohan

    2013-01-01

    Candida infections are very common in cancer patients and it is a common practice to prescribe antifungal antibiotics along with anticancer drugs. Yeast to hyphal form switching is considered to be important in invasive candidiasis. Targeting morphogenetic switching may be useful against invasive candidiasis. In this study, we report the antimorphogenetic properties of thirty cancer drugs. PMID:24516452

  18. Fluorimetric Methods for Analysis of Permeability, Drug Transport Kinetics, and Inhibition of the ABCB1 Membrane Transporter.

    PubMed

    Armada, Ana; Martins, Célia; Spengler, Gabriella; Molnar, Joseph; Amaral, Leonard; Rodrigues, António Sebastião; Viveiros, Miguel

    2016-01-01

    The cell membrane P-glycoprotein (P-gp; MDR1, ABCB1) is an energy-dependent efflux pump that belongs to the ATP-binding cassette (ABC) family of transporters, and has been associated with drug resistance in eukaryotic cells. Multidrug resistance (MDR) is related to an increased expression and function of the ABCB1 (P-gp) efflux pump that often causes chemotherapeutic failure in cancer. Modulators of this efflux pump, such as the calcium channel blocker verapamil (VP) and cyclosporine A (CypA), can reverse the MDR phenotype but in vivo studies have revealed disappointing results due to adverse side effects. Currently available methods are unable to visualize and assess in a real-time basis the effectiveness of ABCB1 inhibitors on the uptake and efflux of ABCB1 substrates. However, predicting and testing ABCB1 modulation activity using living cells during drug development are crucial. The use of ABCB1-transfected mouse T-lymphoma cell line to study the uptake/efflux of fluorescent probes like ethidium bromide (EB), rhodamine 123 (Rh-123), and carbocyanine dye DiOC2, in the presence and absence of potential inhibitors, is currently used in our laboratories to evaluate the ability of a drug to inhibit ABCB1-mediated drug accumulation and efflux. Here we describe and compare three in vitro methods, which evaluate the permeability, transport kinetics of fluorescent substrates, and inhibition of the ABCB1 efflux pump by drugs of chemical synthesis or extracted from natural sources, using model cancer cell lines overexpressing this transporter, namely (1) real-time fluorimetry that assesses the accumulation of ethidium bromide, (2) flow cytometry, and (3) fluorescent microscopy using rhodamine 123 and DiOC2. PMID:26910071

  19. Inhibition of P-glycoprotein function by XR9576 in a solid tumour model can restore anticancer drug efficacy.

    PubMed

    Walker, J; Martin, C; Callaghan, R

    2004-03-01

    Resistance to cancer chemotherapy involves both altered drug activity at the designated target and modified intra-tumour pharmacokinetic properties (e.g. uptake, metabolism). The membrane transporter P-glycoprotein (P-gp) plays a major role in pharmacokinetic resistance by preventing sufficient intracellular accumulation of several anticancer agents. Whilst inhibiting P-gp has great potential to restore chemotherapeutic effectiveness in blood-borne cancers, the situation in solid tumours is less clear. Therefore, the degree of resistance tumours pose to the cytotoxicity of vinblastine and doxorubicin was characterised using the multicellular tumour spheroid model. Tumour spheroids were generated from either drug-sensitive MCF7(WT) breast cancer cells or a resistant P-gp-expressing variant (NCI/ADR(Res)). Drug-induced cytotoxicity in tumour spheroids was measured using an outgrowth assay and compared with that observed in monolayer cultures. As anticipated, the 3-D organisation of MCF7(WT) in tumour spheroids was associated with a reduction in the potency of doxorubicin and vinblastine-i.e. the inherent multicellular resistance phenomenon. In contrast, tumour spheroids from NCI/ADR(Res) cells did not display multicellular resistance. However their constitutive expression of P-gp reduced the potency of both anticancer drugs. Moreover, the highly potent P-gp inhibitor, the anthranilic acid derivative, XR9576, was able to restore the cytotoxic efficacy of both drugs in tumour spheroids comprising NCI/ADR(Res) cells. The results suggest that inhibition of P-gp in solid tumours is achievable and that generation of potent inhibitors will provide a significant benefit towards restoration of chemotherapy in solid tissues. PMID:14962729

  20. Inhibition of ERK pathway or protein synthesis during reexposure to drugs of abuse erases previously learned place preference

    PubMed Central

    Valjent, Emmanuel; Corbillé, Anne-Gaëlle; Bertran-Gonzalez, Jesus; Hervé, Denis; Girault, Jean-Antoine

    2006-01-01

    Repeated association of drugs of abuse with context leads to long-lasting behavioral responses that reflect reward-controlled learning and participate in the establishment of addiction. Reactivation of consolidated memories is known to produce a reconsolidation process during which memories undergo a labile state. We investigated whether reexposure to drugs had similar effects. Cocaine administration activates extracellular signal-regulated kinase (ERK) in the striatum, and ERK activation is required for the acquisition of cocaine-induced conditioned place preference (CPP). When mice previously conditioned for cocaine-place preference were reexposed to cocaine in the drug-paired compartment after systemic administration of SL327, an inhibitor of ERK activation, CPP response was abolished 24 h later. This procedure also abolished the phosphorylation of ERK and glutamate receptor-1 observed in the ventral and dorsal striatum, 24 h later, during CPP test. Erasure of CPP by SL327 required the combination of cocaine administration and drug-paired context and did not result from enhanced extinction. Similarly, reexposure to morphine in the presence of SL327 long-lastingly abolished response of previously learned morphine-CPP. The effects of SL327 on cocaine- or morphine-CPP were reproduced by protein synthesis inhibition. In contrast, protein synthesis inhibition did not alter previously acquired locomotor sensitization to cocaine. Our findings show that an established CPP can be disrupted when reactivation associates both the conditioned context and drug administration. This process involves ERK, and systemic treatment preventing ERK activation during reexposure erases the previously learned behavioral response. These results suggest potential therapeutic strategies to explore in the context of addiction. PMID:16473939

  1. Endogenous opioids mediate the sexual inhibition but not the drug hypersensitivity induced by sexual satiation in male rats.

    PubMed

    Garduño-Gutiérrez, René; Guadarrama-Bazante, Lorena; León-Olea, Martha; Rodríguez-Manzo, Gabriela

    2013-06-01

    Ejaculation promotes endogenous opioid release. Copulation to exhaustion produces several enduring behavioral and physiological changes, among which a long-lasting sexual behavior inhibition and generalized drug hypersensitivity are the most conspicuous. Because copulation to exhaustion involves multiple successive ejaculations, in this work we hypothesized that the endogenous opioids released by multiple ejaculations during the copulation to exhaustion process might mediate the abovementioned sexual satiation-induced changes. To test this hypothesis, sexually experienced male rats were injected with the opioid receptor antagonist naltrexone before copulation to exhaustion and were tested for sexual behavior or drug hypersensitivity 24 h later. The latter was assessed by the appearance of the flat body posture sign of the serotonergic syndrome, in response to doses of the 5-hydroxytryptamine-1A (5-HT1A) receptor agonist 8-hydroxy-2-di-n-propylamino-tetralin (8-OH-DPAT), lower than those normally inducing this sign. The effect of administering naltrexone to already sexually exhausted animals (i.e., 24 h after the sexual satiation process) on both responses was also tested. Results showed that endogenous opioids mediate the establishment and maintenance of the long-lasting sexual behavior inhibition but not the drug hypersensitivity (to 8-OH-DPAT) characteristic of sexually exhausted male rats. It is concluded that although both phenomena appear as a consequence of copulation to satiation and follow a same time course of recovery, they are produced by distinct mechanisms. PMID:23544597

  2. Binding and inhibition of drug transport proteins by heparin: a potential drug transporter modulator capable of reducing multidrug resistance in human cancer cells.

    PubMed

    Chen, Yunliang; Scully, Michael; Petralia, Gloria; Kakkar, Ajay

    2014-01-01

    A major problem in cancer treatment is the development of resistance to chemotherapeutic agents, multidrug resistance (MDR), associated with increased activity of transmembrane drug transporter proteins which impair cytotoxic treatment by rapidly removing the drugs from the targeted cells. Previously, it has been shown that heparin treatment of cancer patients undergoing chemotherapy increases survival. In order to determine whether heparin is capable reducing MDR and increasing the potency of chemotherapeutic drugs, the cytoxicity of a number of agents toward four cancer cell lines (a human enriched breast cancer stem cell line, two human breast cancer cell lines, MCF-7 and MDA-MB-231, and a human lung cancer cell line A549) was tested in the presence or absence of heparin. Results demonstrated that heparin increased the cytotoxicity of a range of chemotherapeutic agents. This effect was associated with the ability of heparin to bind to several of the drug transport proteins of the ABC and non ABC transporter systems. Among the ABC system, heparin treatment caused significant inhibition of the ATPase activity of ABCG2 and ABCC1, and of the efflux function observed as enhanced intracellular accumulation of specific substrates. Doxorubicin cytoxicity, which was enhanced by heparin treatment of MCF-7 cells, was found to be under the control of one of the major non-ABC transporter proteins, lung resistance protein (LRP). LRP was also shown to be a heparin-binding protein. These findings indicate that heparin has a potential role in the clinic as a drug transporter modulator to reduce multidrug resistance in cancer patients. PMID:24253450

  3. Structural basis for the inhibition of Mycobacterium tuberculosis l,d-transpeptidase by meropenem, a drug effective against extensively drug-resistant strains

    PubMed Central

    Kim, Hyoun Sook; Kim, Jieun; Im, Ha Na; Yoon, Ji Young; An, Doo Ri; Yoon, Hye Jin; Kim, Jin Young; Min, Hye Kyeoung; Kim, Soon-Jong; Lee, Jae Young; Han, Byung Woo; Suh, Se Won

    2013-01-01

    Difficulty in the treatment of tuberculosis and growing drug resistance in Mycobacterium tuberculosis (Mtb) are a global health issue. Carbapenems inactivate l,d-transpeptidases; meropenem, when administered with clavulanate, showed in vivo activity against extensively drug-resistant Mtb strains. LdtMt2 (Rv2518c), one of two functional l,d-transpeptidases in Mtb, is predominantly expressed over LdtMt1 (Rv0116c). Here, the crystal structure of N-terminally truncated LdtMt2 (residues Leu131–Ala408) is reported in both ligand-free and meropenem-bound forms. The structure of meropenem-inhibited LdtMt2 provides a detailed structural view of the interactions between a carbapenem drug and Mtb l,d-transpeptidase. The structures revealed that the catalytic l,d-­transpeptidase domain of LdtMt2 is preceded by a bacterial immunogloblin-like Big_5 domain and is followed by an extended C-terminal tail that interacts with both domains. Furthermore, it is shown using mass analyses that meropenem acts as a suicide inhibitor of LdtMt2. Upon acylation of the catalytic Cys354 by meropenem, the ‘active-site lid’ undergoes a large conformational change to partially cover the active site so that the bound meropenem is accessible to the bulk solvent via three narrow paths. This work will facilitate structure-guided discovery of l,d-transpeptidase inhibitors as novel antituberculosis drugs against drug-resistant Mtb. PMID:23519417

  4. Inhibition by morphine and morphine-like drugs of nicotine-induced emesis in cats.

    PubMed

    Beleslin, D B; Krstić, S K; Stefanović-Denić, K; Strbac, M; Mićić, D

    1981-05-01

    The effect of morphine, methadone and pethidine injected into the cerebral ventricle of the unanesthetized cat upon emesis produced by nicotine induced similarly was investigated. Morphine and morphine-like drugs depress or abolish the emetic effect of nicotine. The inhibitory effect of morphine, methadone and pethidine is observed after a transient emetic action of these drugs. The emetic and anti-emetic action of morphine, methadone and pethidine can perhaps be ascribed to an agonist/antagonist activity. Further, the possible site of inhibitory action of morphine and morphine-like drugs on the emesis produced by nicotine may be the area postrema of fourth ventricle. PMID:7248811

  5. Overexpression of uncoupling protein-2 in cancer: metabolic and heat changes, inhibition and effects on drug resistance.

    PubMed

    Pitt, Michael A

    2015-12-01

    This paper deals with the role of uncoupling protein-2 (UCP2) in cancer. UCP2 is overexpressed in cancer. This overexpression results in uncoupling of mitochondrial oxidative phosphorylation and a shift in production of ATP from mitochondrial oxidative phosphorylation to cytosolic aerobic glycolysis. UCP2 overexpression results in the following changes. Mitochondrial membrane potential (Δψ(m)) is decreased and lactate accumulates. There is a diminished production of reactive oxygen species and apoptosis is inhibited post-exposure to chemotherapeutic agents. There is an increase in heat and entropy production and a departure from the stationary state of non-cancerous tissue. Uncoupling of oxidative phosphorylation may also be caused by protonophores and non-steroidal anti-inflammatory drugs. UCP2 requires activation by superoxide and lipid peroxidation derivatives. As vitamin E inhibits lipid peroxidation, it might be expected that vitamin E would act as a chemotherapeutic agent against cancer. A recent study has shown that vitamin E and another anti-oxidant accelerate cancer progression. UCP2 is inhibited by genipin, chromane compounds and short interfering RNAs (siRNA). Genipin, chromanes and siRNA are taken up by both cancer and non-cancerous cells. Targeting the uptake of these agents by cancer cells by the enhanced permeability and retention effect is considered. Inhibition of UCP2 enhances the action of several anti-cancer agents. PMID:26542482

  6. Artemisinin-derived dimer ART-838 potently inhibited human acute leukemias, persisted in vivo, and synergized with antileukemic drugs

    PubMed Central

    Fox, Jennifer M.; Moynihan, James R.; Mott, Bryan T.; Mazzone, Jennifer R.; Anders, Nicole M.; Brown, Patrick A.; Rudek, Michelle A.; Liu, Jun O.; Arav-Boger, Ravit; Posner, Gary H.

    2016-01-01

    Artemisinins, endoperoxide-containing molecules, best known as antimalarials, have potent antineoplastic activity. The established antimalarial, artesunate (AS), and the novel artemisinin-derived trioxane diphenylphosphate dimer 838 (ART-838) inhibited growth of all 23 tested acute leukemia cell lines, reduced cell proliferation and clonogenicity, induced apoptosis, and increased intracellular levels of reactive oxygen species (ROS). ART-838 was 88-fold more potent that AS in vitro, inhibiting all leukemia cell lines at submicromolar concentrations. Both ART-838 and AS cooperated with several established antileukemic drugs and newer kinase inhibitors to inhibit leukemia cell growth. ART-838 had a longer plasma half-life than AS in immunodeficient NOD-SCID-IL2Rgnull (NSG) mice, remaining at effective antileukemic concentrations for >8h. Intermittent cycles of ART-838 inhibited growth of acute leukemia xenografts and primagrafts in NSG mice, at higher potency than AS. Based on these preclinical data, we propose that AS, with its established low toxicity and low cost, and ART-838, with its higher potency and longer persistence in vivo, should be further developed toward integration into antileukemic regimens. PMID:26771236

  7. Ingredients in fruit juices interact with dasatinib through inhibition of BCRP: a new mechanism of beverage-drug interaction.

    PubMed

    Fleisher, Brett; Unum, Jesse; Shao, Jie; An, Guohua

    2015-01-01

    Small molecule tyrosine kinase inhibitors (TKIs) are a group of highly novel and target-specific anticancer drugs. Recently, most TKIs are found to be substrates of P-glycoprotein (P-gp) and Breast Cancer Resistance Protein (BCRP). However, little information is available regarding the Pgp- or BCRP-mediated interaction of TKIs with coadministered drugs/food/beverage. Our objective was to evaluate the effect of the major ingredients of grapefruit juice (GFJ), orange juice (OJ), apple juice (AJ), and green tea on P-gp and BCRP-mediated dasatinib efflux. Among the 14 ingredients screened, only tangeretin and nobiletin moderately inhibited P-gp-mediated dasatinib efflux. In contrast, four ingredients in GFJ [i.e., bergamottin, 6',7'-dihydroxybergamottin (DHB), quercetin, and kaempferol], two ingredients in OJ (tangeretin and nobiletin), and one ingredient in AJ (i.e., hesperetin) greatly inhibited BCRP-mediated dasatinib efflux at the concentration of 50 μM (p < 0.001). Further concentration-dependent studies revealed that bergamottin, DHB, tangeretin, and nobiletin are potent BCRP inhibitors, with IC₅₀ values 3.19, 5.2, 1.19, and 1.04 μM, respectively. Further in vivo investigations are warranted to evaluate the BCRP-mediated FJ-TKI interaction. Literature reports only documented the modulatory effect of FJ and green tea on CYP3A, P-gp, and OATP. Our novel finding that FJ ingredients strongly inhibit BCRP may represent a new mechanism of beverage-drug interaction. PMID:25418056

  8. Marketed Drugs Can Inhibit Cytochrome P450 27A1, a Potential New Target for Breast Cancer Adjuvant Therapy

    PubMed Central

    Mast, Natalia; Lin, Joseph B.

    2015-01-01

    Cytochrome P450 CYP27A1 is the only enzyme in humans converting cholesterol to 27-hydroxycholesterol, an oxysterol of multiple functions, including tissue-specific modulation of estrogen and liver X receptors. Both receptors seem to mediate adverse effects of 27-hydroxycholesterol in breast cancer when the levels of this oxysterol are elevated. The present work assessed druggability of CYP27A1 as a potential antibreast cancer target. We selected 26 anticancer and noncancer medications, most approved by the Food and Drug Administration, and evaluated them first in vitro for inhibition of purified recombinant CYP27A1 and binding to the enzyme active site. Six strong CYP27A1 inhibitors/binders were identified. These were the two antibreast cancer pharmaceuticals anastrozole and fadrozole, antiprostate cancer drug bicalutamide, sedative dexmedetomidine, and two antifungals ravuconazole and posaconazole. Anastrozole was then tested in vivo on mice, which received subcutaneous drug injections for 1 week. Mouse plasma and hepatic 27-hydroxycholesterol levels were decreased 2.6- and 1.6-fold, respectively, whereas plasma and hepatic cholesterol content remained unchanged. Thus, pharmacologic CYP27A1 inhibition is possible in the whole body and individual organs, but does not negatively affect cholesterol elimination. Our results enhance the potential of CYP27A1 as an antibreast cancer target, could be of importance for the interpretation of Femara versus Anastrozole Clinical Evaluation Trial, and bring attention to posaconazole as a potential complementary anti-breast cancer medication. More medications on the US market may have unanticipated off-target inhibition of CYP27A1, and we propose strategies for their identification. PMID:26082378

  9. The enriched fraction of Elephantopus scaber Triggers apoptosis and inhibits multi-drug resistance transporters in human epithelial cancer cells

    PubMed Central

    Beeran, Asmy Appadath; Maliyakkal, Naseer; Rao, Chamallamudi Mallikarjuna; Udupa, Nayanabhirama

    2015-01-01

    Background: Medicinal plants have played an important role in the development of clinically useful anticancer agents. Elephantopus scaber (Asteraceae) (ES) is widely used in Indian traditional system of medicine for the treatment of various ailments including cancer. Objective: To investigate anticancer effects of ES in human epithelial cancer cells. Materials and Methods: Cytotoxicity of ethanolic extract of ES (ES-ET) and its fractions, such as ES Petroleum ether fraction (ES-PET), ES Dichloromethane fraction (ES DCM), n Butyl alcohol fraction (ES-BT), and ES-Rest (ES-R) were assessed in human epithelial cancer cell lines using sulforhodamine B (SRB) assay. Acridine orange/ethidium bromide assay and Hoechst 33342 assays were used to gauge induction of apoptosis. Cell cycle analysis and micronuclei assay were used to assess cell cycle specific pharmacological effects and drug induced genotoxicty. Further, the ability of ES to inhibit multi drug resistant (MDR) transporters (ABC-B1 and ABC-G2) was determined by Rhodamine (Rho) and Mitoxantrone (MXR) efflux assays. Results: The enriched fraction of ES (ES DCM) possessed dose-dependent potent cytotoxicity in human epithelial cancer cells. Further, treatment of cancer cells (HeLa, A549, MCF-7, and Caco-2) with ES DCM showed hall mark properties of apoptosis (membrane blebbing, nuclear condensation etc.). Similarly, ES DCM caused enhanced sub G0 content and micronuclei formation indicating the induction of apoptosis and drug induced genotoxicity in cancer cells, respectively. Interestingly, ES DCM inhibited MDR transporters (ABC B1 and ABC G2) in cancer cells. Conclusion: The enriched fraction of ES imparted cytotoxic effects, triggered apoptosis, induced genotoxicity, and inhibited MDR transporters in human epithelial cancer cells. Thus, ES appears to be potential anticancer agent. PMID:25829763

  10. Marketed Drugs Can Inhibit Cytochrome P450 27A1, a Potential New Target for Breast Cancer Adjuvant Therapy.

    PubMed

    Mast, Natalia; Lin, Joseph B; Pikuleva, Irina A

    2015-09-01

    Cytochrome P450 CYP27A1 is the only enzyme in humans converting cholesterol to 27-hydroxycholesterol, an oxysterol of multiple functions, including tissue-specific modulation of estrogen and liver X receptors. Both receptors seem to mediate adverse effects of 27-hydroxycholesterol in breast cancer when the levels of this oxysterol are elevated. The present work assessed druggability of CYP27A1 as a potential antibreast cancer target. We selected 26 anticancer and noncancer medications, most approved by the Food and Drug Administration, and evaluated them first in vitro for inhibition of purified recombinant CYP27A1 and binding to the enzyme active site. Six strong CYP27A1 inhibitors/binders were identified. These were the two antibreast cancer pharmaceuticals anastrozole and fadrozole, antiprostate cancer drug bicalutamide, sedative dexmedetomidine, and two antifungals ravuconazole and posaconazole. Anastrozole was then tested in vivo on mice, which received subcutaneous drug injections for 1 week. Mouse plasma and hepatic 27-hydroxycholesterol levels were decreased 2.6- and 1.6-fold, respectively, whereas plasma and hepatic cholesterol content remained unchanged. Thus, pharmacologic CYP27A1 inhibition is possible in the whole body and individual organs, but does not negatively affect cholesterol elimination. Our results enhance the potential of CYP27A1 as an antibreast cancer target, could be of importance for the interpretation of Femara versus Anastrozole Clinical Evaluation Trial, and bring attention to posaconazole as a potential complementary anti-breast cancer medication. More medications on the US market may have unanticipated off-target inhibition of CYP27A1, and we propose strategies for their identification. PMID:26082378

  11. Polysome shift assay for direct measurement of miRNA inhibition by anti-miRNA drugs

    PubMed Central

    Androsavich, John R.; Sobczynski, Daniel J.; Liu, Xueqing; Pandya, Shweta; Kaimal, Vivek; Owen, Tate; Liu, Kai; MacKenna, Deidre A.; Chau, B. Nelson

    2016-01-01

    Anti-miRNA (anti-miR) oligonucleotide drugs are being developed to inhibit overactive miRNAs linked to disease. To help facilitate the transition from concept to clinic, new research tools are required. Here we report a novel method—miRNA Polysome Shift Assay (miPSA)—for direct measurement of miRNA engagement by anti-miR, which is more robust than conventional pharmacodynamics using downstream target gene derepression. The method takes advantage of size differences between active and inhibited miRNA complexes. Active miRNAs bind target mRNAs in high molecular weight polysome complexes, while inhibited miRNAs are sterically blocked by anti-miRs from forming this interaction. These two states can be assessed by fractionating tissue or cell lysates using differential ultracentrifugation through sucrose gradients. Accordingly, anti-miR treatment causes a specific shift of cognate miRNA from heavy to light density fractions. The magnitude of this shift is dose-responsive and maintains a linear relationship with downstream target gene derepression while providing a substantially higher dynamic window for aiding drug discovery. In contrast, we found that the commonly used ‘RT-interference’ approach, which assumes that inhibited miRNA is undetectable by RT-qPCR, can yield unreliable results that poorly reflect the binding stoichiometry of anti-miR to miRNA. We also demonstrate that the miPSA has additional utility in assessing anti-miR cross-reactivity with miRNAs sharing similar seed sequences. PMID:26384419

  12. Polysome shift assay for direct measurement of miRNA inhibition by anti-miRNA drugs.

    PubMed

    Androsavich, John R; Sobczynski, Daniel J; Liu, Xueqing; Pandya, Shweta; Kaimal, Vivek; Owen, Tate; Liu, Kai; MacKenna, Deidre A; Chau, B Nelson

    2016-01-29

    Anti-miRNA (anti-miR) oligonucleotide drugs are being developed to inhibit overactive miRNAs linked to disease. To help facilitate the transition from concept to clinic, new research tools are required. Here we report a novel method--miRNA Polysome Shift Assay (miPSA)--for direct measurement of miRNA engagement by anti-miR, which is more robust than conventional pharmacodynamics using downstream target gene derepression. The method takes advantage of size differences between active and inhibited miRNA complexes. Active miRNAs bind target mRNAs in high molecular weight polysome complexes, while inhibited miRNAs are sterically blocked by anti-miRs from forming this interaction. These two states can be assessed by fractionating tissue or cell lysates using differential ultracentrifugation through sucrose gradients. Accordingly, anti-miR treatment causes a specific shift of cognate miRNA from heavy to light density fractions. The magnitude of this shift is dose-responsive and maintains a linear relationship with downstream target gene derepression while providing a substantially higher dynamic window for aiding drug discovery. In contrast, we found that the commonly used 'RT-interference' approach, which assumes that inhibited miRNA is undetectable by RT-qPCR, can yield unreliable results that poorly reflect the binding stoichiometry of anti-miR to miRNA. We also demonstrate that the miPSA has additional utility in assessing anti-miR cross-reactivity with miRNAs sharing similar seed sequences. PMID:26384419

  13. Large scale integration of drug-target information reveals poly-pharmacological drug action mechanisms in tumor cell line growth inhibition assays

    PubMed Central

    Knight, Richard A.; Gostev, Mikhail; Ilisavskii, Sergei; Willis, Anne E.; Melino, Gerry; Antonov, Alexey V.

    2014-01-01

    Understanding therapeutic mechanisms of drug anticancer cytotoxicity represents a key challenge in preclinical testing. Here we have performed a meta-analysis of publicly available tumor cell line growth inhibition assays (~ 70 assays from 6 independent experimental groups covering ~ 500 000 molecules) with the primary goal of understanding molecular therapeutic mechanisms of cancer cytotoxicity. To implement this we have collected currently available information on protein targets for molecules that were tested in the assays. We used a statistical methodology to identify protein targets overrepresented among molecules exhibiting cancer cytotoxicity with the particular focus of identifying overrepresented patterns consisting of several proteins (i.e. proteins “A” and “B” and “C”). Our analysis demonstrates that targeting individual proteins can result in a significant increase (up to 50-fold) of the observed odds for a molecule to be an efficient inhibitor of tumour cell line growth. However, further insight into potential molecular mechanisms reveals a multi-target mode of action: targeting a pattern of several proteins drastically increases the observed odds (up to 500-fold) for a molecule to be tumour cytotoxic. In contrast, molecules targeting only one protein but not targeting an additional set of proteins tend to be nontoxic. Our findings support a poly-pharmacology drug discovery paradigm, demonstrating that anticancer cytotoxicity is a product, in most cases, of multi-target mode of drug action PMID:24553133

  14. Screening of Drugs Inhibiting In vitro Oligomerization of Cu/Zn-Superoxide Dismutase with a Mutation Causing Amyotrophic Lateral Sclerosis

    PubMed Central

    Anzai, Itsuki; Toichi, Keisuke; Tokuda, Eiichi; Mukaiyama, Atsushi; Akiyama, Shuji; Furukawa, Yoshiaki

    2016-01-01

    Dominant mutations in Cu/Zn-superoxide dismutase (SOD1) gene have been shown to cause a familial form of amyotrophic lateral sclerosis (SOD1-ALS). A major pathological hallmark of this disease is abnormal accumulation of mutant SOD1 oligomers in the affected spinal motor neurons. While no effective therapeutics for SOD1-ALS is currently available, SOD1 oligomerization will be a good target for developing cures of this disease. Recently, we have reproduced the formation of SOD1 oligomers abnormally cross-linked via disulfide bonds in a test tube. Using our in vitro model of SOD1 oligomerization, therefore, we screened 640 FDA-approved drugs for inhibiting the oligomerization of SOD1 proteins, and three effective classes of chemical compounds were identified. Those hit compounds will provide valuable information on the chemical structures for developing a novel drug candidate suppressing the abnormal oligomerization of mutant SOD1 and possibly curing the disease. PMID:27556028

  15. Screening of Drugs Inhibiting In vitro Oligomerization of Cu/Zn-Superoxide Dismutase with a Mutation Causing Amyotrophic Lateral Sclerosis.

    PubMed

    Anzai, Itsuki; Toichi, Keisuke; Tokuda, Eiichi; Mukaiyama, Atsushi; Akiyama, Shuji; Furukawa, Yoshiaki

    2016-01-01

    Dominant mutations in Cu/Zn-superoxide dismutase (SOD1) gene have been shown to cause a familial form of amyotrophic lateral sclerosis (SOD1-ALS). A major pathological hallmark of this disease is abnormal accumulation of mutant SOD1 oligomers in the affected spinal motor neurons. While no effective therapeutics for SOD1-ALS is currently available, SOD1 oligomerization will be a good target for developing cures of this disease. Recently, we have reproduced the formation of SOD1 oligomers abnormally cross-linked via disulfide bonds in a test tube. Using our in vitro model of SOD1 oligomerization, therefore, we screened 640 FDA-approved drugs for inhibiting the oligomerization of SOD1 proteins, and three effective classes of chemical compounds were identified. Those hit compounds will provide valuable information on the chemical structures for developing a novel drug candidate suppressing the abnormal oligomerization of mutant SOD1 and possibly curing the disease. PMID:27556028

  16. Antibiotic drug tigecycline reduces neuroblastoma cells proliferation by inhibiting Akt activation in vitro and in vivo.

    PubMed

    Zhong, Xiaoxia; Zhao, Erhu; Tang, Chunling; Zhang, Weibo; Tan, Juan; Dong, Zhen; Ding, Han-Fei; Cui, Hongjuan

    2016-06-01

    As the first member of glycylcycline bacteriostatic agents, tigecycline is approved as a novel expanded-spectrum antibiotic, which is clinically available. However, accumulating evidence indicated that tigecycline was provided with the potential application in cancer therapy. In this paper, tigecycline was shown to exert an anti-proliferative effect on neuroblastoma cell lines. Furthermore, it was found that tigecycline induced G1-phase cell cycle arrest instead of apoptosis by means of Akt pathway inhibition. In neuroblastoma cell lines, the Akt activator insulin-like growth factor-1 (hereafter referred to as IGF-1) reversed tigecycline-induced cell cycle arrest. Besides, tigecycline inhibited colony formation and suppressed neuroblastoma cells xenograft formation and growth. After tigecycline treatment in vivo, the Akt pathway inhibition was confirmed as well. Collectively, our data provided strong evidences that tigecycline inhibited neuroblastoma cells growth and proliferation through the Akt pathway inhibition in vitro and in vivo. In addition, these results were supported by previous studies concerning the application of tigecycline in human tumors treatment, suggesting that tigecycline might act as a potential candidate agent for neuroblastoma treatment. PMID:26687647

  17. In vitro assessment of metabolic drug-drug interaction potential of apixaban through cytochrome P450 phenotyping, inhibition, and induction studies.

    PubMed

    Wang, Lifei; Zhang, Donglu; Raghavan, Nirmala; Yao, Ming; Ma, Li; Frost, Charles E; Frost, Charles A; Maxwell, Brad D; Chen, Shiang-yuan; He, Kan; Goosen, Theunis C; Humphreys, W Griffith; Grossman, Scott J

    2010-03-01

    Apixaban is an oral, direct, and highly selective factor Xa inhibitor in late-stage clinical development for the prevention and treatment of thromboembolic diseases. The metabolic drug-drug interaction potential of apixaban was evaluated in vitro. The compound did not show cytochrome P450 inhibition (IC(50) values >20 microM) in incubations of human liver microsomes with the probe substrates of CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, or 3A4/5. Apixaban did not show any effect at concentrations up to 20 muM on enzyme activities or mRNA levels of selected P450 enzymes (CYP1A2, 2B6, and 3A4/5) that are sensitive to induction in incubations with primary human hepatocytes. Apixaban showed a slow metabolic turnover in incubations of human liver microsomes with formation of O-demethylation (M2) and hydroxylation products (M4 and M7) as prominent in vitro metabolites. Experiments with human cDNA-expressed P450 enzymes and P450 chemical inhibitors and correlation with P450 activities in individual human liver microsomes demonstrated that the oxidative metabolism of apixaban for formation of all metabolites was predominantly catalyzed by CYP3A4/5 with a minor contribution of CYP1A2 and CYP2J2 for formation of M2. The contribution of CYP2C8, 2C9, and 2C19 to metabolism of apixaban was less significant. In addition, a human absorption, distribution, metabolism, and excretion study showed that more than half of the dose was excreted as unchanged parent (f(m CYP) <0.5), thus significantly reducing the overall metabolic drug-drug interaction potential of apixaban. Together with a low clinical efficacious concentration and multiple clearance pathways, these results demonstrate that the metabolic drug-drug interaction potential between apixaban and coadministered drugs is low. PMID:19940026

  18. RND-type drug efflux pumps from Gram-negative bacteria: molecular mechanism and inhibition

    PubMed Central

    Venter, Henrietta; Mowla, Rumana; Ohene-Agyei, Thelma; Ma, Shutao

    2015-01-01

    Drug efflux protein complexes confer multidrug resistance on bacteria by transporting a wide spectrum of structurally diverse antibiotics. Moreover, organisms can only acquire resistance in the presence of an active efflux pump. The substrate range of drug efflux pumps is not limited to antibiotics, but it also includes toxins, dyes, detergents, lipids, and molecules involved in quorum sensing; hence efflux pumps are also associated with virulence and biofilm formation. Inhibitors of efflux pumps are therefore attractive compounds to reverse multidrug resistance and to prevent the development of resistance in clinically relevant bacterial pathogens. Recent successes on the structure determination and functional analysis of the AcrB and MexB components of the AcrAB-TolC and MexAB-OprM drug efflux systems as well as the structure of the fully assembled, functional triparted AcrAB-TolC complex significantly contributed to our understanding of the mechanism of substrate transport and the options for inhibition of efflux. These data, combined with the well-developed methodologies for measuring efflux pump inhibition, could allow the rational design, and subsequent experimental verification of potential efflux pump inhibitors (EPIs). In this review we will explore how the available biochemical and structural information can be translated into the discovery and development of new compounds that could reverse drug resistance in Gram-negative pathogens. The current literature on EPIs will also be analyzed and the reasons why no compounds have yet progressed into clinical use will be explored. PMID:25972857

  19. Marked enhancement of lysosomal targeting and efficacy of ErbB2-targeted drug delivery by HSP90 inhibition

    PubMed Central

    Mohapatra, Bhopal; Luan, Haitao; Soni, Kruti; Zhang, Jinjin; Storck, Matthew A.; Feng, Dan; Bielecki, Timothy A.; Band, Vimla; Cohen, Samuel M.; Bronich, Tatiana K.; Band, Hamid

    2016-01-01

    Targeted delivery of anticancer drugs to tumor cells using monoclonal antibodies against oncogenic cell surface receptors is an emerging therapeutic strategy. These strategies include drugs directly conjugated to monoclonal antibodies through chemical linkers (Antibody-Drug Conjugates, ADCs) or those encapsulated within nanoparticles that in turn are conjugated to targeting antibodies (Antibody-Nanoparticle Conjugates, ANPs). The recent FDA approval of the ADC Trastuzumab-TDM1 (Kadcyla®; Genentech; San Francisco) for the treatment of ErbB2-overexpressing metastatic breast cancer patients has validated the strong potential of these strategies. Even though the activity of ANPs and ADCs is dependent on lysosomal traffic, the roles of the endocytic route traversed by the targeted receptor and of cancer cell-specific alterations in receptor dynamics on the efficiency of drug delivery have not been considered in these new targeted therapies. For example, constitutive association with the molecular chaperone HSP90 is thought to either retard ErbB2 endocytosis or to promote its recycling, traits undesirable for targeted therapy with ANPs and ADCs. HSP90 inhibitors are known to promote ErbB2 ubiquitination, targeting to lysosome and degradation. We therefore hypothesized that ErbB2-targeted drug delivery using Trastuzumab-conjugated nanoparticles could be significantly improved by HSP90 inhibitor-promoted lysosomal traffic of ErbB2. Studies reported here validate this hypothesis and demonstrate, both in vitro and in vivo, that HSP90 inhibition facilitates the intracellular delivery of Trastuzumab-conjugated ANPs carrying a model chemotherapeutic agent, Doxorubicin, specifically into ErbB2-overexpressing breast cancer cells, resulting in improved antitumor activity. These novel findings highlight the need to consider oncogene-specific alterations in receptor traffic in the design of targeted drug delivery strategies. We suggest that combination of agents that enhance

  20. Antiepileptic drugs with histone deacetylase inhibition activity and prostate cancer risk: a population-based case-control study.

    PubMed

    Salminen, Jukka K; Tammela, Teuvo L J; Auvinen, Anssi; Murtola, Teemu J

    2016-05-01

    Previous studies suggest that antiepileptic drugs with histone deacetylase (HDAC) inhibitor properties may have prostate cancer preventive effects. We evaluated the association between antiepileptic drug use and prostate cancer risk in a population-based case-control study. The study included all new prostate cancer cases diagnosed in Finland in 1995-2002 and matched controls (24,657 case-control pairs) identified from the Finnish Cancer Registry and the Population Register Center, respectively. Information on antiepileptic drug purchases was obtained from the national prescription reimbursement database. Odds ratios and their 95 % confidence intervals were estimated using age-adjusted and multivariable-adjusted conditional logistic regression analysis. Compared to never-users of antiepileptic drugs, the overall prostate cancer risk was decreased among users of phenobarbital, carbamazepine, and valproic acid (multivariable-adjusted odds ratio (OR) 0.47, 95 % CI 0.24-0.92; OR 0.82, 95 % CI 0.71-0.94, and OR 0.62, 95 % CI 0.42-0.92, respectively), but not among users of other antiepileptic drugs. Overall prostate cancer risk decreased in a dose-dependent manner by cumulative amount, duration and yearly dosage (intensity) of HDAC inhibitors valproic acid and carbamazepine. The risk of advanced prostate cancer was decreased only among carbamazepine users (OR 0.65, 95 % CI 0.44-0.96). Our results support possible prostate cancer preventive effects of HDAC inhibitors. However, also phenobarbital use was associated with decreased prostate cancer risk, despite not having HDAC inhibiting activity. The mechanism of action for antiepileptic drugs in prostate cancer deserves further study. PMID:27038166

  1. Marked enhancement of lysosomal targeting and efficacy of ErbB2-targeted drug delivery by HSP90 inhibition.

    PubMed

    Raja, Srikumar M; Desale, Swapnil S; Mohapatra, Bhopal; Luan, Haitao; Soni, Kruti; Zhang, Jinjin; Storck, Matthew A; Feng, Dan; Bielecki, Timothy A; Band, Vimla; Cohen, Samuel M; Bronich, Tatiana K; Band, Hamid

    2016-03-01

    Targeted delivery of anticancer drugs to tumor cells using monoclonal antibodies against oncogenic cell surface receptors is an emerging therapeutic strategy. These strategies include drugs directly conjugated to monoclonal antibodies through chemical linkers (Antibody-Drug Conjugates, ADCs) or those encapsulated within nanoparticles that in turn are conjugated to targeting antibodies (Antibody-Nanoparticle Conjugates, ANPs). The recent FDA approval of the ADC Trastuzumab-TDM1 (Kadcyla; Genentech; San Francisco) for the treatment of ErbB2-overexpressing metastatic breast cancer patients has validated the strong potential of these strategies. Even though the activity of ANPs and ADCs is dependent on lysosomal traffic, the roles of the endocytic route traversed by the targeted receptor and of cancer cell-specific alterations in receptor dynamics on the efficiency of drug delivery have not been considered in these new targeted therapies. For example, constitutive association with the molecular chaperone HSP90 is thought to either retard ErbB2 endocytosis or to promote its recycling, traits undesirable for targeted therapy with ANPs and ADCs. HSP90 inhibitors are known to promote ErbB2 ubiquitination, targeting to lysosome and degradation. We therefore hypothesized that ErbB2-targeted drug delivery using Trastuzumab-conjugated nanoparticles could be significantly improved by HSP90 inhibitor-promoted lysosomal traffic of ErbB2. Studies reported here validate this hypothesis and demonstrate, both in vitro and in vivo, that HSP90 inhibition facilitates the intracellular delivery of Trastuzumab-conjugated ANPs carrying a model chemotherapeutic agent, Doxorubicin, specifically into ErbB2-overexpressing breast cancer cells, resulting in improved antitumor activity. These novel findings highlight the need to consider oncogene-specific alterations in receptor traffic in the design of targeted drug delivery strategies. We suggest that combination of agents that enhance receptor

  2. The Evolution of Interspecific Mutualisms

    NASA Astrophysics Data System (ADS)

    Doebeli, Michael; Knowlton, Nancy

    1998-07-01

    Interspecific mutualisms are widespread, but how they evolve is not clear. The Iterated Prisoner's Dilemma is the main theoretical tool to study cooperation, but this model ignores ecological differences between partners and assumes that amounts exchanged cannot themselves evolve. A more realistic model incorporating these features shows that strategies that succeed with fixed exchanges (e.g., Tit-for-Tat) cannot explain mutualism when exchanges vary because the amount exchanged evolves to 0. For mutualism to evolve, increased investments in a partner must yield increased returns, and spatial structure in competitive interactions is required. Under these biologically plausible assumptions, mutualism evolves with surprising ease. This suggests that, contrary to the basic premise of past theoretical analyses, overcoming a potential host's initial defenses may be a bigger obstacle for mutualism than the subsequent recurrence and spread of noncooperative mutants.

  3. Estimating mutual information.

    PubMed

    Kraskov, Alexander; Stögbauer, Harald; Grassberger, Peter

    2004-06-01

    We present two classes of improved estimators for mutual information M(X,Y), from samples of random points distributed according to some joint probability density mu(x,y). In contrast to conventional estimators based on binnings, they are based on entropy estimates from k -nearest neighbor distances. This means that they are data efficient (with k=1 we resolve structures down to the smallest possible scales), adaptive (the resolution is higher where data are more numerous), and have minimal bias. Indeed, the bias of the underlying entropy estimates is mainly due to nonuniformity of the density at the smallest resolved scale, giving typically systematic errors which scale as functions of k/N for N points. Numerically, we find that both families become exact for independent distributions, i.e. the estimator M(X,Y) vanishes (up to statistical fluctuations) if mu(x,y)=mu(x)mu(y). This holds for all tested marginal distributions and for all dimensions of x and y. In addition, we give estimators for redundancies between more than two random variables. We compare our algorithms in detail with existing algorithms. Finally, we demonstrate the usefulness of our estimators for assessing the actual independence of components obtained from independent component analysis (ICA), for improving ICA, and for estimating the reliability of blind source separation. PMID:15244698

  4. [Biological mutualism, concepts and models].

    PubMed

    Perru, Olivier

    2011-01-01

    Mutualism is a biological association for a mutual benefit between two different species. In this paper, firstly, we examine the history and signification of mutualism in relation to symbiosis. Then, we consider the link between concepts and models of mutualism. Models of mutualism depend on different concepts we use: If mutualism is situated at populations' level, it will be expressed by Lotka-Volterra models, concerning exclusively populations' size. If mutualism is considered as a resources' exchange or a biological market increasing the fitness of these organisms, it will be described at an individual level by a cost-benefit model. Our analysis will be limited to the history and epistemology of Lotka-Volterra models and we hypothesize that these models are adapted at first to translate dynamic evolutions of mutualism. They render stability or variations of size and assume that there are clear distinctions and a state of equilibrium between populations of different species. Italian mathematician Vito Volterra demonstrated that biological associations consist in a constant relation between some species. In 1931 and 1935, Volterra described the general form of antagonistic or mutualistic biological associations by the same differential equations. We recognize that these equations have been more used to model competition or prey-predator interactions, but a simple sign change allows describing mutualism. The epistemological problem is the following: Volterra's equations help us to conceptualize a global phenomenon. However, mutualistic interactions may have stronger effects away from equilibrium and these effects may be better understood at individual level. We conclude that, between 1985 and 2000, some researchers carried on working and converting Lotka-Volterra models but this description appeared as insufficient. So, other researchers adopted an economical viewpoint, considering mutualism as a biological market. PMID:22288336

  5. Perspectives on Inhibiting β-Amyloid Aggregation through Structure-Based Drug Design.

    PubMed

    Mishra, Pankaj; Ayyannan, Senthil R; Panda, Gautam

    2015-09-01

    Targeting β-amyloid (Aβ) remains the most desired strategy in Alzheimer's disease (AD) drug discovery research. Many peptides that specifically target Aβ aggregates are known, encompassing efforts from both industrial and academic research settings. However, in clinical terms, not much success has been gained with peptide research; in turn, small drug-like molecules are already globally recognized as showing promise as an alternate approach. Aβ aggregation inhibitors are the most important part of the multifunctional drug design regimen for treating AD. Unfortunately, rational drug design approaches with small molecules are still in the initial stages. Herein we highlight, update, and elaborate on the structural anatomy of Aβ and known Aβ aggregation inhibitors in hopes of helping to optimize their use in structure-based drug design approaches toward inhibitors with greater specificity. Furthermore, we present the first review of efforts to target a previously uncharacterized region of acetylcholinesterase: the N-terminal 7-20 sub-region, which was experimentally elucidated to participate in Aβ aggregation and deposition. PMID:26230674

  6. Repurposing of antiparasitic drugs: the hydroxy-naphthoquinone buparvaquone inhibits vertical transmission in the pregnant neosporosis mouse model.

    PubMed

    Müller, Joachim; Aguado-Martínez, Adriana; Manser, Vera; Wong, Ho Ning; Haynes, Richard K; Hemphill, Andrew

    2016-01-01

    The three anti-malarial drugs artemiside, artemisone, and mefloquine, and the naphthoquinone buparvaquone known to be active against theileriosis in cattle and Leishmania infections in rodents, were assessed for activity against Neospora caninum infection. All four compounds inhibited the proliferation of N. caninum tachyzoites in vitro with IC50 in the sub-micromolar range, but artemisone and buparvaquone were most effective (IC50 = 3 and 4.9 nM, respectively). However, in a neosporosis mouse model for cerebral infection comprising Balb/c mice experimentally infected with the virulent isolate Nc-Spain7, the three anti-malarial compounds failed to exhibit any activity, since treatment did not reduce the parasite burden in brains and lungs compared to untreated controls. Thus, these compounds were not further evaluated in pregnant mice. On the other hand, buparvaquone, shown earlier to be effective in reducing the parasite load in the lungs in an acute neosporosis disease model, was further assessed in the pregnant mouse model. Buparvaquone efficiently inhibited vertical transmission in Balb/c mice experimentally infected at day 7 of pregnancy, reduced clinical signs in the pups, but had no effect on cerebral infection in the dams. This demonstrates proof-of-concept that drug repurposing may lead to the discovery of an effective compound against neosporosis that can protect offspring from vertical transmission and disease. PMID:26883424

  7. In vitro Plasmodium falciparum drug sensitivity assay: inhibition of parasite growth by incorporation of stomatocytogenic amphiphiles into the erythrocyte membrane.

    PubMed

    Ziegler, Hanne L; Staerk, Dan; Christensen, Jette; Hviid, Lars; Hägerstrand, Henry; Jaroszewski, Jerzy W

    2002-05-01

    Lupeol, which shows in vitro inhibitory activity against Plasmodium falciparum 3D7 strain with a 50% inhibitory concentration (IC50) of 27.7 +/- 0.5 microM, was shown to cause a transformation of the human erythrocyte shape toward that of stomatocytes. Good correlation between the IC50 value and the membrane curvature changes caused by lupeol was observed. Preincubation of erythrocytes with lupeol, followed by extensive washing, made the cells unsuitable for parasite growth, suggesting that the compound incorporates into erythrocyte membrane irreversibly. On the other hand, lupeol-treated parasite culture continued to grow well in untreated erythrocytes. Thus, the antiplasmodial activity of lupeol appears to be indirect, being due to stomatocytic transformation of the host cell membrane and not to toxic effects via action on a drug target within the parasite. A number of amphiphiles that cause stomatocyte formation, but not those causing echinocyte formation, were shown to inhibit growth of the parasites, apparently via a mechanism similar to that of lupeol. Since antiplasmodial agents that inhibit parasite growth through erythrocyte membrane modifications must be regarded as unsuitable as leads for development of new antimalarial drugs, care must be exercised in the interpretation of results of screening of plant extracts and natural product libraries by an in vitro Plasmodium toxicity assay. PMID:11959580

  8. In Vitro Plasmodium falciparum Drug Sensitivity Assay: Inhibition of Parasite Growth by Incorporation of Stomatocytogenic Amphiphiles into the Erythrocyte Membrane

    PubMed Central

    Ziegler, Hanne L.; Stærk, Dan; Christensen, Jette; Hviid, Lars; Hägerstrand, Henry; Jaroszewski, Jerzy W.

    2002-01-01

    Lupeol, which shows in vitro inhibitory activity against Plasmodium falciparum 3D7 strain with a 50% inhibitory concentration (IC50) of 27.7 ± 0.5 μM, was shown to cause a transformation of the human erythrocyte shape toward that of stomatocytes. Good correlation between the IC50 value and the membrane curvature changes caused by lupeol was observed. Preincubation of erythrocytes with lupeol, followed by extensive washing, made the cells unsuitable for parasite growth, suggesting that the compound incorporates into erythrocyte membrane irreversibly. On the other hand, lupeol-treated parasite culture continued to grow well in untreated erythrocytes. Thus, the antiplasmodial activity of lupeol appears to be indirect, being due to stomatocytic transformation of the host cell membrane and not to toxic effects via action on a drug target within the parasite. A number of amphiphiles that cause stomatocyte formation, but not those causing echinocyte formation, were shown to inhibit growth of the parasites, apparently via a mechanism similar to that of lupeol. Since antiplasmodial agents that inhibit parasite growth through erythrocyte membrane modifications must be regarded as unsuitable as leads for development of new antimalarial drugs, care must be exercised in the interpretation of results of screening of plant extracts and natural product libraries by an in vitro Plasmodium toxicity assay. PMID:11959580

  9. The clinically approved drugs dasatinib and bosutinib induce anti-inflammatory macrophages by inhibiting the salt-inducible kinases

    PubMed Central

    Ozanne, James; Prescott, Alan R.; Clark, Kristopher

    2014-01-01

    Macrophages switch to an anti-inflammatory, ‘regulatory’-like phenotype characterized by the production of high levels of interleukin (IL)-10 and low levels of pro-inflammatory cytokines to promote the resolution of inflammation. A potential therapeutic strategy for the treatment of chronic inflammatory diseases would be to administer drugs that could induce the formation of ‘regulatory’-like macrophages at sites of inflammation. In the present study, we demonstrate that the clinically approved cancer drugs bosutinib and dasatinib induce several hallmark features of ‘regulatory’-like macrophages. Treatment of macrophages with bosutinib or dasatinib elevates the production of IL-10 while suppressing the production of IL-6, IL-12p40 and tumour necrosis factor α (TNFα) in response to Toll-like receptor (TLR) stimulation. Moreover, macrophages treated with bosutinib or dasatinib express higher levels of markers of ‘regulatory’-like macrophages including LIGHT, SPHK1 and arginase 1. Bosutinib and dasatinib were originally developed as inhibitors of the protein tyrosine kinases Bcr-Abl and Src but we show that, surprisingly, the effects of bosutinib and dasatinib on macrophage polarization are the result of the inhibition of the salt-inducible kinases. Consistent with the present finding, bosutinib and dasatinib induce the dephosphorylation of CREB-regulated transcription co-activator 3 (CRTC3) and its nuclear translocation where it induces a cAMP-response-element-binding protein (CREB)-dependent gene transcription programme including that of IL-10. Importantly, these effects of bosutinib and dasatinib on IL-10 gene expression are lost in macrophages expressing a drug-resistant mutant of salt-inducible kinase 2 (SIK2). In conclusion, our study identifies the salt-inducible kinases as major targets of bosutinib and dasatinib that mediate the effects of these drugs on the innate immune system and provides novel mechanistic insights into the anti

  10. Inhibition of bile salt transport by drugs associated with liver injury in primary hepatocytes from human, monkey, dog, rat, and mouse.

    PubMed

    Zhang, Jie; He, Kan; Cai, Lining; Chen, Yu-Chuan; Yang, Yifan; Shi, Qin; Woolf, Thomas F; Ge, Weigong; Guo, Lei; Borlak, Jürgen; Tong, Weida

    2016-08-01

    Interference of bile salt transport is one of the underlying mechanisms for drug-induced liver injury (DILI). We developed a novel bile salt transport activity assay involving in situ biosynthesis of bile salts from their precursors in primary human, monkey, dog, rat, and mouse hepatocytes in suspension as well as LC-MS/MS determination of extracellular bile salts transported out of hepatocytes. Glycine- and taurine-conjugated bile acids were rapidly formed in hepatocytes and effectively transported into the extracellular medium. The bile salt formation and transport activities were time‒ and bile-acid-concentration‒dependent in primary human hepatocytes. The transport activity was inhibited by the bile salt export pump (BSEP) inhibitors ketoconazole, saquinavir, cyclosporine, and troglitazone. The assay was used to test 86 drugs for their potential to inhibit bile salt transport activity in human hepatocytes, which included 35 drugs associated with severe DILI (sDILI) and 51 with non-severe DILI (non-sDILI). Approximately 60% of the sDILI drugs showed potent inhibition (with IC50 values <50 μM), but only about 20% of the non-sDILI drugs showed this strength of inhibition in primary human hepatocytes and these drugs are associated only with cholestatic and mixed hepatocellular cholestatic (mixed) injuries. The sDILI drugs, which did not show substantial inhibition of bile salt transport activity, are likely to be associated with immune-mediated liver injury. Twenty-four drugs were also tested in monkey, dog, rat and mouse hepatocytes. Species differences in potency were observed with mouse being less sensitive than other species to inhibition of bile salt transport. In summary, a novel assay has been developed using hepatocytes in suspension from human and animal species that can be used to assess the potential for drugs and/or drug-derived metabolites to inhibit bile salt transport and/or formation activity. Drugs causing sDILI, except those by immune

  11. An isocorydine derivative (d-ICD) inhibits drug resistance by downregulating IGF2BP3 expression in hepatocellular carcinoma

    PubMed Central

    Ge, Chao; Chen, Lijuan; Fang, Tao; Li, Hong; Tian, Hua; Liu, Junxi; Chen, Taoyang; Jiang, Guoping; Xie, Haiyang; Cui, Ying; Yao, Ming; Li, Jinjun

    2015-01-01

    In our previous studies, we reported that CD133+ cancer stem cells (CSCs) were chemoresistant in hepatocellular carcinoma (HCC) and that isocorydine treatment decreased the percentage of CD133+ CSCs. Here, we found that a derivative of isocorydine (d-ICD) inhibited HCC cell growth, particularly among the CD133+ subpopulation, and rendered HCC cells more sensitive to sorafenib treatment. d-ICD inhibited IGF2BP3 expression in a time-dependent manner, and IGF2BP3 expression negatively correlated with d-ICD-induced growth suppression. IGF2BP3 overexpression enriched the CD133+ CSC subpopulation in HCC, enhanced tumor sphere formation and suppressed the cytotoxic effects of sorafenib and doxorubicin. The expression of drug resistance-related genes, including ABCB1 and ABCG2, and the CSC marker CD133 expression was increased after IGF2BP3 overexpression. The significance of these observations was underscored by our findings that high IGF2BP3 expression predicted poor survival in a cohort of 236 patients with HCC and positively correlated with ABCG2 and CD133 expression in vivo. These results suggested that the d-ICD may inhibit HCC cells growth by IGF2BP3 decrease and that IGF2BP3 may serve as a therapeutic target for HCC. PMID:26327240

  12. Thiopurine drugs azathioprine and 6-mercaptopurine inhibit Mycobacterium paratuberculosis growth in vitro.

    PubMed

    Shin, Sung Jae; Collins, Michael T

    2008-02-01

    The in vitro susceptibility of human- and bovine-origin Mycobacterium paratuberculosis to the thioupurine drugs 6-mercaptopurine (6-MP) and azathioprine (AZA) was established using conventional plate counting methods and the MGIT 960 ParaTB culture system. Both 6-MP and AZA had antibacterial activity against M. paratuberculosis; isolates from Crohn's disease patients tended to be more susceptible than were bovine-origin isolates. Isolates of Mycobacterium avium, used as controls, were generally resistant to both AZA and 6-MP, even at high concentrations (> or =64.0 microg/ml). Among rapidly growing mycobacteria, Mycobacterium phlei was susceptible to 6-MP and AZA whereas Mycobacterium smegmatis strains were not. AZA and 6-MP limited the growth of, but did not kill, M. paratuberculosis in a dose-dependent manner. Anti-inflammatory drugs in the sulfonamide family (sulfapyridine, sulfasalazine, and 5-aminosalycilic acid [mesalamine]) had little or no antibacterial activity against M. paratuberculosis. The conventional antibiotics azithromycin and ciprofloxacin, used as control drugs, were bactericidal for M. paratuberculosis, exerting their killing effects on the organism relatively quickly. Simultaneous exposure of M. paratuberculosis to 6-MP and ciprofloxacin resulted in significantly higher CFU than use of ciprofloxacin alone. These data may partially explain the paradoxical response of Crohn's disease patients infected with M. paratuberculosis to treatment with immunosuppressive thiopurine drugs, i.e., they do not worsen with anti-inflammatory treatment as would be expected with a microbiological etiologic pathogen. These findings also should influence the design of therapeutic trials to evaluate antibiotic treatments of Crohn's disease: AZA drugs may confound interpretation of data on therapeutic responses for both antibiotic-treated and control groups. PMID:18070971

  13. The anti-inflammatory drug nimesulide inhibits neutrophil adherence to and migration across monolayers of cytokine-activated endothelial cells.

    PubMed

    Dapino, P; Ottonello, L; Dallegri, F

    1994-01-01

    Neutrophil migration through the microvascular endothelium represents a fundamental event for the cell accumulation at sites of tissue injury. Owing to their capacity to modify the structural and functional characteristics of endothelial cells, inflammatory cytokines such as interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF alpha) play a pivotal role in directing circulating neutrophils away from the bloodstream to the interstitial tissue. In order to study neutrophil transendothelial migration, human umbilical vein endothelial cells were grown to confluence on the polycarbonate filter of two-compartment migration chambers. Pretreatment of the endothelial cell monolayers with TNF alpha for 4 h resulted in rapid migration of approximately 50% of subsequently added neutrophils across the layers. In contrast, < 10% of added neutrophils penetrated untreated endothelial monolayers. Using TNF alpha-treated endothelium, neutrophil transmigration was inhibited by the methane sulfonanilide anti-inflammatory drug nimesulide. Moreover, neutrophil adherence to TNF alpha-treated endothelial monolayers, cultured in microtiter wells, was markedly reduced by nimesulide. A linear correlation between the drug-dependent inhibition of neutrophil transmigration and neutrophil adherence was found. Finally, nimesulide did not interfere with the TNF alpha ability to convert resting endothelium into a pro-adhesive and pro-locomotory cell layer. The data suggest that nimesulide reduces neutrophil transendothelial migration primarily by limiting the cell anchorage to the TNF alpha-activated endothelium. Therefore, the drug has the potential to down-regulate neutrophil extravasation and, in turn, the burden of neutrophil oxidants and proteases leading to tissue injury at sites of inflammation. PMID:7824814

  14. Parental substance abuse and function of the motivation and behavioral inhibition systems in drug-naïve youth.

    PubMed

    Ivanov, Iliyan; Liu, Xun; Shulz, Kurt; Fan, Jin; London, Edythe; Friston, Karl; Halperin, Jeffrey M; Newcorn, Jeffrey H

    2012-02-28

    It is hypothesized that the development of substance abuse (SA) may be due to imbalance in functions of the motivation-reward and behavioral inhibition systems in the brain. This speaks to the search for biological risk factors for SA in drug-naïve children who also exhibit motivational and inhibitory control deficits; however, this type of research is currently lacking. The objective of this study was to establish a neurobiological basis for addiction vulnerability using functional magnetic resonance imaging (fMRI) in drug-naïve youth with attention deficit/hyperactivity disorder (ADHD). We hypothesized that children with ADHD alone would show higher activity in regions of the motivation-reward and behavioral inhibition systems than children with ADHD and a parental history of SA. Toward this goal we scanned 20 drug-naïve children with ADHD ages 8-13 while performing an event-related reward task. High (N=10) and low (N=10) risk subjects were identified, based on parental history of SA. The effects of anticipation, conflict, and reward were assessed with appropriate linear contrasts, and between-group differences were assessed using statistical parametric mapping. The two groups did not differ on behavioral measures of the task. The fMRI results show heightened activation in the brain motivational-reward system and reduced activation of the inhibitory control system in high-risk compared to low-risk children. These results suggest that a functional mismatch between these two systems may represent one possible biological underpinning of SA risk, which is conferred by a parental history of addiction. PMID:22386967

  15. Co-treatment with grapefruit juice inhibits while chronic administration activates intestinal P-glycoprotein-mediated drug efflux.

    PubMed

    Panchagnula, R; Bansal, T; Varma, M V S; Kaul, C L

    2005-12-01

    P-Glycoprotein (P-gp) mediated efflux is recognized as a significant biochemical barrier affecting oral absorption for a number of drugs. Various conflicting reports have been published regarding the effects of grapefruit juice (GFJ) on P-gp-mediated drug efflux, in which GFJ has been shown both to inhibit and activate it. Hence, the present study adopted a two-way approach, involving both co-treatment and chronic administration. Bi-directional transport of paclitaxel (PCL) was carried out in the absence and presence of GFJ extract, in rat everted ileum sac. Further, the effect of chronic administration of GFJ to rats was characterized by permeability studies with indinavir (INDI). Co-treatment of GFJ extract at 100% concentration reduced the asymmetric transport of PCL (efflux ratio = 20.8) by increasing absorptive (A --> B) transport by 921% and reducing secretory (B --> A) transport by 41%. Further, GFJ showed a concentration dependent effect on PCL permeability. Imipramine, a passive permeability marker with absorptive permeability of 15.33 +/- 4.26 x 10(-6) cm/s showed no asymmetric transport and also no significant (P < 0.05) change in permeability in the presence of GFJ. Chronic administration of GFJ resulted in a significant decrease in absorptive transport of indinavir, which was even greater than that produced by rifampicin pretreatment. No change in permeability of propranolol, a passive permeability marker, was observed. Further, the decrease in absorptive transport of INDI was reversed by the P-gp inhibitor verapamil. In conclusion, GFJ extract inhibited P-gp-mediated efflux in co-treatment, whereas chronic administration led to increased levels of P-gp expression, thus having a profound effect on intestinal absorption and GFJ-drug interactions in vivo. PMID:16398269

  16. Grief and Palliative Care: Mutuality

    PubMed Central

    Moon, Paul J

    2013-01-01

    Grief and palliative care are interrelated and perhaps mutually inclusive. Conceptually and practically, grief intimately relates to palliative care, as both domains regard the phenomena of loss, suffering, and a desire for abatement of pain burden. Moreover, the notions of palliative care and grief may be construed as being mutually inclusive in terms of one cueing the other. As such, the discussions in this article will center on the conceptualizations of the mutuality between grief and palliative care related to end-of-life circumstances. Specifically, the complementarity of grief and palliative care, as well as a controvertible view thereof, will be considered. PMID:25278758

  17. Individual Constituents from Essential Oils Inhibit Biofilm Mass Production by Multi-Drug Resistant Staphylococcus aureus.

    PubMed

    Espina, Laura; Pagán, Rafael; López, Daniel; García-Gonzalo, Diego

    2015-01-01

    Biofilm formation by Staphylococcus aureus represents a problem in both the medical field and the food industry, because the biofilm structure provides protection to embedded cells and it strongly attaches to surfaces. This circumstance is leading to many research programs seeking new alternatives to control biofilm formation by this pathogen. In this study we show that a potent inhibition of biofilm mass production can be achieved in community-associated methicillin-resistant S. aureus (CA-MRSA) and methicillin-sensitive strains using plant compounds, such as individual constituents (ICs) of essential oils (carvacrol, citral, and (+)-limonene). The Crystal Violet staining technique was used to evaluate biofilm mass formation during 40 h of incubation. Carvacrol is the most effective IC, abrogating biofilm formation in all strains tested, while CA-MRSA was the most sensitive phenotype to any of the ICs tested. Inhibition of planktonic cells by ICs during initial growth stages could partially explain the inhibition of biofilm formation. Overall, our results show the potential of EOs to prevent biofilm formation, especially in strains that exhibit resistance to other antimicrobials. As these compounds are food additives generally recognized as safe, their anti-biofilm properties may lead to important new applications, such as sanitizers, in the food industry or in clinical settings. PMID:26102069

  18. The antipsoriatic drug, anthralin, inhibits protein kinase C--implications for its mechanism of action.

    PubMed

    Hegemann, L; Fruchtmann, R; van Rooijen, L A; Müller-Peddinghaus, R; Mahrle, G

    1992-01-01

    In psoriatic patients, anthralin is known to attenuate lesional inflammation, but often generates perilesional dermatitis. This phenomenon is well reflected by the contrasting action of anthralin on human leukocytes. The release of reactive oxygen species (ROS) is inhibited by anthralin in phorbol ester-activated leukocytes, whereas anthralin directly induces this cellular response in unstimulated cells. In order to elaborate further the underlying mechanisms, we compared the kinetics of anthralin and different well-characterized stimuli, including the phorbol ester, phorbol-12-myristate-13-acetate, in this test system. Compared with standard stimuli, anthralin only marginally induced the release of ROS from human leukocytes and displayed different kinetics. Protein kinase C (PKC), the major cellular phorbol ester receptor, is considered to be involved in the regulation of this cellular response. Furthermore, its involvement in the pathophysiology of psoriasis has been suggested. Therefore, we also investigated the effects of anthralin on purified PKC. Anthralin was found to inhibit the enzyme activity in a dose-dependent manner but not to display any stimulatory effects. The present results provide first evidence that the therapeutic activity of anthralin, at least in part, might be mediated by inhibition of PKC. PMID:1503504

  19. Inhibition of human insulin gene transcription by peroxisome proliferator-activated receptor γ and thiazolidinedione oral antidiabetic drugs

    PubMed Central

    Schinner, S; Krätzner, R; Baun, D; Dickel, C; Blume, R; Oetjen, E

    2009-01-01

    Background and purpose: The transcription factor peroxisome proliferator-activated receptor γ (PPARγ) is essential for glucose homeostasis. PPARγ ligands reducing insulin levels in vivo are used as drugs to treat type 2 diabetes mellitus. Genes regulated by PPARγ have been found in several tissues including insulin-producing pancreatic islet β-cells. However, the role of PPARγ at the insulin gene was unknown. Therefore, the effect of PPARγ and PPARγ ligands like rosiglitazone on insulin gene transcription was investigated. Experimental approach: Reporter gene assays were used in the β-cell line HIT and in primary mature pancreatic islets of transgenic mice. Mapping studies and internal mutations were carried out to locate PPARγ-responsive promoter regions. Key results: Rosiglitazone caused a PPARγ-dependent inhibition of insulin gene transcription in a β-cell line. This inhibition was concentration-dependent and had an EC50 similar to that for the activation of a reporter gene under the control of multimerized PPAR binding sites. Also in normal primary pancreatic islets of transgenic mice, known to express high levels of PPARγ, rosiglitazone inhibited glucose-stimulated insulin gene transcription. Transactivation and mapping experiments suggest that, in contrast to the rat glucagon gene, the inhibition of the human insulin gene promoter by PPARγ/rosiglitazone does not depend on promoter-bound Pax6 and is attributable to the proximal insulin gene promoter region around the transcription start site from −56 to +18. Conclusions and implications: The human insulin gene represents a novel PPARγ target that may contribute to the action of thiazolidinediones in type 2 diabetes mellitus. PMID:19338578

  20. Differential In Vitro Inhibition of Thrombin Generation by Anticoagulant Drugs in Plasma from Patients with Cirrhosis

    PubMed Central

    Potze, Wilma; Arshad, Freeha; Adelmeijer, Jelle; Blokzijl, Hans; van den Berg, Arie P.; Meijers, Joost C. M.; Porte, Robert J.; Lisman, Ton

    2014-01-01

    Background Treatment and prevention of thrombotic complications is frequently required in patients with cirrhosis. However anticoagulant therapy is often withheld from these patients, because of the perceived bleeding diathesis. As a result of the limited clinical experience, the anticoagulant of choice for the various indications is still not known. Objectives We evaluated the in vitro effect of clinically approved anticoagulant drugs in plasma from patients with cirrhosis. Patients/Methods Thirty patients with cirrhosis and thirty healthy controls were studied. Thrombin generation assays were performed before and after addition of unfractionated heparin, low molecular weight heparin, fondaparinux, dabigatran, and rivaroxaban, to estimate anticoagulant potencies of these drugs. Results Addition of dabigatran led to a much more pronounced reduction in endogenous thrombin potential in patients compared to controls (72.6% reduction in patients vs. 12.8% reduction in controls, P<0.0001). The enhanced effect of dabigatran was proportional to the severity of disease. In contrast, only a slightly increased anticoagulant response to heparin and low molecular weight heparin and even a reduced response to fondaparinux and rivaroxaban was observed in plasma from cirrhotic patients as compared to control plasma. Conclusions The anticoagulant potency of clinically approved drugs differs substantially between patients with cirrhosis and healthy individuals. Whereas dabigatran and, to a lesser extent, heparin and low molecular weight heparin are more potent in plasma from patients with cirrhosis, fondaparinux and rivaroxaban showed a decreased anticoagulant effect. These results may imply that in addition to dose adjustments based on altered pharmacokinetics, drug-specific dose adjustments based on altered anticoagulant potency may be required in patients with cirrhosis. PMID:24505487

  1. Enhanced QSAR models for drug-triggered inhibition of the main cardiac ion currents.

    PubMed

    Wiśniowska, Barbara; Mendyk, Aleksander; Szlęk, Jakub; Kołaczkowski, Michał; Polak, Sebastian

    2015-09-01

    The currently changing cardiac safety testing paradigm suggests, among other things, a shift towards using in silico models of cellular electrophysiology and assessment of a concomitant block of multiple ion channels. In this study, a set of four enhanced QSAR models have been developed: for the rapid delayed rectifying potassium current (IKr), slow delayed rectifying potassium current (IKs), peak sodium current (INa) and late calcium current (ICaL), predicting ion currents changes for the specific in vitro experiment from the 2D structure of the compounds. The models are a combination of both in vitro study parameters and physico-chemical descriptors, which is a novel approach in drug-ion channels interactions modeling. Their predictive power assessed in the enhanced, more demanding than standard procedure, 10-fold cross validation was reasonably high. Rough comparison with published pure in silico hERG interaction models shows that the quality of the model predictions does not differ from other models available in the public domain, however, it takes its advantage in accounting for inter-experimental settings variability. Developed models are implemented in the Cardiac Safety Simulator, a commercially available platform enabling the in vitro-in vivo extrapolation of the drugs proarrhythmic effect and ECG simulation. A more comprehensive assessment of the effects of the compounds on ion channels allows for making more informed decisions regarding the risk - and thus avoidance - of exclusion of potentially safe and effective drugs. PMID:25559930

  2. Analgesic-antiinflammatory drugs inhibit orbicularis oculi reflexes in humans via a central mode of action.

    PubMed

    Ferracuti, S; Leardi, M G; Cruccu, G; Fabbri, A; Itil, T M

    1994-01-01

    1. A cross-over single blind study examined the possible central effects of non-opioid analgesic drugs on the trigeminal reflexes. 2. The corneal reflex and blink reflex (R1, R2) were recorded electromyographically and response areas measured in healthy volunteers before and after intramuscular injection of piroxicam (40 mg); and after intravenous injection of lysine acetylsalicylate (500 mg). After the last drug recording the subjects received intravenous naloxone (2 mg) followed 5 minutes later by further reflex testing. Saline was used as a placebo in control experiments. 3. Both analgesics reduced the corneal reflex: piroxicam induced a 27% and lysine acetylsalicylate a 21% a reduction that naloxone did not reverse. Neither drug reduced the early or the late component of the blink reflex. 4. The marked inhibitory changes that the two non-narcotic analgesics produced on the corneal reflex--a nociceptive response--indicate a centrally-mediated action. 5. Naloxone's failure to reverse the induced analgesia argues against opiate receptor mediation. PMID:8115666

  3. Mutually Exclusive Expression of Virulence Genes by Malaria Parasites Is Regulated Independently of Antigen Production

    PubMed Central

    Dzikowski, Ron; Frank, Matthias; Deitsch, Kirk

    2006-01-01

    The primary virulence determinant of Plasmodium falciparum malaria parasite–infected cells is a family of heterogeneous surface receptors collectively referred to as PfEMP1. These proteins are encoded by a large, polymorphic gene family called var. The family contains approximately 60 individual genes, which are subject to strict, mutually exclusive expression, with the single expressed var gene determining the antigenic, cytoadherent, and virulence phenotype of the infected cell. The mutually exclusive expression pattern of var genes is imperative for the parasite's ability to evade the host's immune response and is similar to the process of “allelic exclusion” described for mammalian Ig and odorant receptor genes. In mammalian systems, mutually exclusive expression is ensured by negative feedback inhibition mediated by production of a functional protein. To investigate how expression of the var gene family is regulated, we have created transgenic lines of parasites in which expression of individual var loci can be manipulated. Here we show that no such negative feedback system exists in P. falciparum and that this process is dependent solely on the transcriptional regulatory elements immediately adjacent to each gene. Transgenic parasites that are selected to express a var gene in which the PfEMP1 coding region has been replaced by a drug-selectable marker silence all other var genes in the genome, thus effectively knocking out all PfEMP1 expression and indicating that the modified gene is still recognized as a member of the var gene family. Mutually exclusive expression in P. falciparum is therefore regulated exclusively at the level of transcription, and a functional PfEMP1 protein is not necessary for viability or for proper gene regulation in cultured parasites. PMID:16518466

  4. Inhibition of Neuronal Degenerin/Epithelial Na+ Channels by the Multiple Sclerosis Drug 4-Aminopyridine*

    PubMed Central

    Boiko, Nina; Kucher, Volodymyr; Eaton, Benjamin A.; Stockand, James D.

    2013-01-01

    The voltage-gated K+ (Kv) channel blocker 4-aminopyridine (4-AP) is used to target symptoms of the neuroinflammatory disease multiple sclerosis (MS). By blocking Kv channels, 4-AP facilitates action potential conduction and neurotransmitter release in presynaptic neurons, lessening the effects of demyelination. Because they conduct inward Na+ and Ca2+ currents that contribute to axonal degeneration in response to inflammatory conditions, acid-sensing ion channels (ASICs) contribute to the pathology of MS. Consequently, ASICs are emerging as disease-modifying targets in MS. Surprisingly, as first demonstrated here, 4-AP inhibits neuronal degenerin/epithelial Na+ (Deg/ENaC) channels, including ASIC and BLINaC. This effect is specific for 4-AP compared with its heterocyclic base, pyridine, and the related derivative, 4-methylpyridine; and akin to the actions of 4-AP on the structurally unrelated Kv channels, dose- and voltage-dependent. 4-AP has differential actions on distinct ASICs, strongly inhibiting ASIC1a channels expressed in central neurons but being without effect on ASIC3, which is enriched in peripheral sensory neurons. The voltage dependence of the 4-AP block and the single binding site for this inhibitor are consistent with 4-AP binding in the pore of Deg/ENaC channels as it does Kv channels, suggesting a similar mechanism of inhibition in these two classes of channels. These findings argue that effects on both Kv and Deg/ENaC channels should be considered when evaluating the actions of 4-AP. Importantly, the current results are consistent with 4-AP influencing the symptoms of MS as well as the course of the disease because of inhibitory actions on Kv and ASIC channels, respectively. PMID:23404498

  5. Autophagic flux inhibition and lysosomogenesis ensuing cellular capture and retention of the cationic drug quinacrine in murine models.

    PubMed

    Parks, Alexandre; Charest-Morin, Xavier; Boivin-Welch, Michael; Bouthillier, Johanne; Marceau, Francois

    2015-01-01

    The proton pump vacuolar (V)-ATPase is the driving force that mediates the concentration of cationic drugs (weak bases) in the late endosome-lysosome continuum; secondary cell reactions include the protracted transformation of enlarged vacuoles into autophagosomes. We used the inherently fluorescent tertiary amine quinacrine in murine models to further assess the accumulation and signaling associated with cation trapping. Primary fibroblasts concentrate quinacrine ∼5,000-fold from their culture medium (KM 9.8 µM; transport studies). The drug is present in perinuclear granules that are mostly positive for Rab7 and LAMP1 (microscopy). Both drug uptake and retention are extensively inhibited by treatments with the V-ATPase inhibitor bafilomycin A1. The H(+) ionophore monensin also prevented quinacrine concentration by fibroblasts. However, inhibition of plasma membrane transporters or of the autophagic process with spautin-1 did not alter quinacrine transport parameters. Ancillary experiments did not support that low micromolar concentrations of quinacrine are substrates for organic cation transporters-1 to -3 or P-glycoprotein. The secondary autophagy induced by quinacrine in cells may derive from the accumulation of incompetent autophagolysosomes, as judged from the accumulation of p62/SQSTM1 and LC3 II (immunoblots). Accordingly, protracted lysosomogenesis is evidenced by increased expression of LAMP1 and LAMP2 in quinacrine-treated fibroblasts (48 h, immunoblots), a response that follows the nuclear translocation of the lysosomal genesis transcription factor TFEB and upregulation of LAMP1 and -2 mRNAs (24 h). Quinacrine administration to live mice evidenced variable distribution to various organs and heterogeneous accumulation within the lung (stereo-microscopy, extraction). Dose-dependent in vivo autophagic and lysosomal accumulation was observed in the lung (immunoblots). No evidence has been found for transport or extrusion mechanisms modulating the cellular

  6. Autophagic flux inhibition and lysosomogenesis ensuing cellular capture and retention of the cationic drug quinacrine in murine models

    PubMed Central

    Parks, Alexandre; Charest-Morin, Xavier; Boivin-Welch, Michael; Bouthillier, Johanne

    2015-01-01

    The proton pump vacuolar (V)-ATPase is the driving force that mediates the concentration of cationic drugs (weak bases) in the late endosome-lysosome continuum; secondary cell reactions include the protracted transformation of enlarged vacuoles into autophagosomes. We used the inherently fluorescent tertiary amine quinacrine in murine models to further assess the accumulation and signaling associated with cation trapping. Primary fibroblasts concentrate quinacrine ∼5,000-fold from their culture medium (KM 9.8 µM; transport studies). The drug is present in perinuclear granules that are mostly positive for Rab7 and LAMP1 (microscopy). Both drug uptake and retention are extensively inhibited by treatments with the V-ATPase inhibitor bafilomycin A1. The H+ ionophore monensin also prevented quinacrine concentration by fibroblasts. However, inhibition of plasma membrane transporters or of the autophagic process with spautin-1 did not alter quinacrine transport parameters. Ancillary experiments did not support that low micromolar concentrations of quinacrine are substrates for organic cation transporters-1 to -3 or P-glycoprotein. The secondary autophagy induced by quinacrine in cells may derive from the accumulation of incompetent autophagolysosomes, as judged from the accumulation of p62/SQSTM1 and LC3 II (immunoblots). Accordingly, protracted lysosomogenesis is evidenced by increased expression of LAMP1 and LAMP2 in quinacrine-treated fibroblasts (48 h, immunoblots), a response that follows the nuclear translocation of the lysosomal genesis transcription factor TFEB and upregulation of LAMP1 and −2 mRNAs (24 h). Quinacrine administration to live mice evidenced variable distribution to various organs and heterogeneous accumulation within the lung (stereo-microscopy, extraction). Dose-dependent in vivo autophagic and lysosomal accumulation was observed in the lung (immunoblots). No evidence has been found for transport or extrusion mechanisms modulating the cellular

  7. Turning Ineffective Transplatin into a Highly Potent Anticancer Drug via a Prodrug Strategy for Drug Delivery and Inhibiting Cisplatin Drug Resistance.

    PubMed

    Li, Wenliang; Jiang, Mo; Cao, Yue; Yan, Lesan; Qi, Ruogu; Li, Yuxin; Jing, Xiabin

    2016-08-17

    Clinically ineffective transplatin is highly potent against cancer cells when transformed into a transplatin(IV) prodrug nanoparticle. Herein, a hydrophobic transplatin(IV) was synthesized by H2O2-oxidization of transplatin and attachment of two hydrophobic aliphatic chains. Transplatin(IV) was subsequently encapsulated by a biodegradable amphiphilic copolymer, MPEG-PLA, forming a well-defined spherical micelles (M(TransPt)). Transplatin(IV) was protected efficiently and could be released under a simulated cancerous intracellular condition. Compared to the cisplatin and transplatin, M(TransPt) showed the highest Pt uptake and a clathrin-dependent endocytosis pathway. Most importantly, M(TransPt) displayed a nanomolar IC50 on A2780 cells and a great potency on cisplatin resistant A2780DDP cell line. Overall, this nanoplatform for delivering trans-geometry platinum(IV) drug exhibits excellent characteristics for enhancing efficacy and overcoming cisplatin drug resistance, and holds a strong promise for clinical use in the near future. PMID:27380489

  8. Adamantyl Analogues of Paracetamol as Potent Analgesic Drugs via Inhibition of TRPA1

    PubMed Central

    Fresno, Nieves; Pérez-Fernández, Ruth; Goicoechea, Carlos; Alkorta, Ibon; Fernández-Carvajal, Asia; de la Torre-Martínez, Roberto; Quirce, Susana; Ferrer-Montiel, Antonio; Martín, M. Isabel; Goya, Pilar; Elguero, José

    2014-01-01

    Paracetamol also known as acetaminophen, is a widely used analgesic and antipyretic agent. We report the synthesis and biological evaluation of adamantyl analogues of paracetamol with important analgesic properties. The mechanism of nociception of compound 6a/b, an analog of paracetamol, is not exerted through direct interaction with cannabinoid receptors, nor by inhibiting COX. It behaves as an interesting selective TRPA1 channel antagonist, which may be responsible for its analgesic properties, whereas it has no effect on the TRPM8 nor TRPV1 channels. The possibility of replacing a phenyl ring by an adamantyl ring opens new avenues in other fields of medicinal chemistry. PMID:25438056

  9. Inhibition of bone loss with surface-modulated, drug-loaded nanoparticles in an intraosseous model of prostate cancer.

    PubMed

    Adjei, Isaac M; Sharma, Blanka; Peetla, Chiranjeevi; Labhasetwar, Vinod

    2016-06-28

    Advanced-stage prostate cancer usually metastasizes to bone and is untreatable due to poor biodistribution of intravenously administered anticancer drugs to bone. In this study, we modulated the surface charge/composition of biodegradable nanoparticles (NPs) to sustain their blood circulation time and made them small enough to extravasate through the openings of the bone's sinusoidal capillaries and thus localize into marrow. NPs with a neutral surface charge, achieved by modulating the NP surface-associated emulsifier composition, were more effective at localizing to bone marrow than NPs with a cationic or anionic surface charge. These small neutral NPs (~150nm vs. the more usual ~320nm) were also ~7-fold more effective in localizing in bone marrow than large NPs. We hypothesized that NPs that effectively localize to marrow could improve NP-mediated anticancer drug delivery to sites of bone metastasis, thereby inhibiting cancer progression and preventing bone loss. In a PC-3M-luc cell-induced osteolytic intraosseous model of prostate cancer, these small neutral NPs demonstrated greater accumulation in bone within metastatic sites than in normal contralateral bone as well as co-localization with the tumor mass in marrow. Significantly, a single-dose intravenous administration of these small neutral NPs loaded with paclitaxel (PTX-NPs), but not anionic PTX-NPs, slowed the progression of bone metastasis. In addition, neutral PTX-NPs prevented bone loss, whereas animals treated with the rapid-release drug formulation Cremophor EL (PTX-CrEL) or saline (control) showed >50% bone loss. Neutral PTX-NPs did not cause acute toxicity, whereas animals treated with PTX-CrEL experienced weight loss. These results indicate that NPs with appropriate physical and sustained drug-release characteristics could be explored to treat bone metastasis, a significant clinical issue in prostate and other cancers. PMID:27090164

  10. Inhibition of primary and metastatic tumors in mice by E-selectin-targeted polymer-drug conjugates.

    PubMed

    Shamay, Yosi; Raviv, Lior; Golan, Moran; Voronov, Elena; Apte, Ron N; David, Ayelet

    2015-11-10

    There is currently no effective means to prevent or control metastatic dissemination of cancer cells. E-selectin, an adhesion molecule expressed exclusively on inflamed and angiogenic blood vessels, plays an important role in several rate-limiting steps of cancer metastasis. In this study, we assessed the in vivo antitumor efficacy of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers conjugated to an E-selectin binding peptide (Esbp, DITWDQLWDLMK) and equipped with the chemotherapeutic drug doxorubicin (P-(Esbp)-DOX) or with the proapoptotic peptide D(KLAKLAK)2 (P-(Esbp)-KLAK). Following a single intravenous injection, P-(Esbp)-DOX reduced tumor growth rate and prolonged the survival of mice bearing primary Lewis lung carcinoma (3LL) tumors significantly more than treatment with a non-targeted copolymer (P-DOX) or with free DOX. In an experimental B16-F10 lung metastasis model, a single intravenous dose of P-(Esbp)-DOX or P-(Esbp)-KLAK prolonged mice survival time significantly more than the non-targeted copolymers or the free drugs, and the percentage of complete tumor regression increased with increasing doses and with dosing frequency. In addition, mice pretreated with an E-selectin-targeted "drug-free" copolymer (P-(Esbp)-FITC) exhibited significantly fewer B16-F10 tumor foci in the lungs as compared with non-treated mice, demonstrating the anti-metastatic properties of the copolymer and its ability to control cancer spread through E-selectin-mediated interactions. Biodistribution analysis further confirmed the preferential accumulation of the E-selectin-targeted near-infrared fluorescently-labeled copolymer P-(Esbp)-IR783 in B16-F10 lung metastases. Taken together, this study demonstrates, for the first time, that the E-selectin targeted copolymer-drug conjugates can inhibit primary tumor growth and prevent metastases in vivo. PMID:26297207