RESUMEN
Salmonella enterica subsp. enterica serovar 4,[5],12:i:- is a monophasic variant of Salmonella Typhimurium. In this study, a total of 651 human and 107 food and environmental isolates of serovar 4,[5],12:i:- recovered from 2007 through 2011 in Switzerland were characterized by antibiotic resistance profiles and pulsed-field gel electrophoresis (PFGE). In addition, a selection of isolates belonging to the most frequent PFGE patterns was further subjected to multilocus variable-number tandem-repeat analysis (MLVA) and phage typing. Over the years 2007-2011, the reports of salmonellosis caused by Salmonella enterica serovar 4,[5],12:i:- significantly increased. A high prevalence of multidrug-resistant isolates, mainly showing an ampicillin-streptomycin-sulfonamide-tetracycline resistance pattern (ASSuT), was observed. In addition, four extended spectrum beta lactamase (ESBL) (CTX-M-55)-producing isolates were found. XbaI PFGE analysis of all isolates revealed over 150 different pulsotypes, and generally showed a considerable diversity within the monophasic isolates. Nevertheless, among these we identified seven dominant profiles, which encompassed 66% of all isolates tested. The PFGE type STYMXB.0131 dominated among human as well as food isolates. Multilocus variable-number tandem-repeat analysis profile 3-12-10-0-0211, which, in many cases, coincided with PFGE type STYMXB.0131 and phage type DT193 were the most prevalent types found for the isolates further characterized by these typing methods. Our data provide strong evidence for a spread of two specific Salmonella serovar 4,[5],12:i:- clones (PFGE pattern STYMXB.0131, resistance type ASSuT) and (PFGE pattern STYMXB.0131, resistance type SSuT). In contrast to the human isolates, the pork/poultry isolates expressed predominantly the SSuT resistance type.
Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple , Carne/microbiología , Infecciones por Salmonella/microbiología , Salmonella enterica/efectos de los fármacos , Salmonella typhimurium/efectos de los fármacos , Microbiología del Agua , Animales , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Tipificación de Bacteriófagos , Bacteriófagos/clasificación , Bacteriófagos/crecimiento & desarrollo , Bacteriófagos/aislamiento & purificación , Pollos/microbiología , Monitoreo del Ambiente , Heces/microbiología , Humanos , Pruebas de Sensibilidad Microbiana , Tipificación de Secuencias Multilocus , Salmonella enterica/clasificación , Salmonella enterica/aislamiento & purificación , Salmonella enterica/virología , Salmonella typhimurium/clasificación , Salmonella typhimurium/aislamiento & purificación , Salmonella typhimurium/virología , Metiltransferasa de ADN de Sitio Específico (Adenina Especifica)/genética , Metiltransferasa de ADN de Sitio Específico (Adenina Especifica)/metabolismo , Sus scrofa/microbiología , SuizaRESUMEN
Cancer stem cells are known for their inherent resistance to therapy. Here we investigated whether normal stem cells with acquired resistance to stress can be used to identify novel markers of cancer stem cells. For this, we generated a human embryonic stem cell line resistant to Trichostatin A and analyzed changes in its gene expression. The resistant cells over-expressed various genes associated with tumor aggressiveness, many of which are also expressed in the CD133+ glioma cancer stem cells. These findings suggest that stress-resistant stem cells generated in vitro may be useful for the discovery of novel markers of cancer stem cells.
Asunto(s)
Antígenos CD/metabolismo , Biomarcadores de Tumor/genética , Resistencia a Antineoplásicos , Células Madre Embrionarias/metabolismo , Regulación Neoplásica de la Expresión Génica/fisiología , Glicoproteínas/metabolismo , Ácidos Hidroxámicos/farmacología , Células Madre Neoplásicas/metabolismo , Péptidos/metabolismo , Antígeno AC133 , Western Blotting , Diferenciación Celular , Células Cultivadas , Células Madre Embrionarias/patología , Perfilación de la Expresión Génica , Humanos , Técnicas para Inmunoenzimas , Células Madre Neoplásicas/patología , Análisis de Secuencia por Matrices de Oligonucleótidos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Increased neovasculature and resistance to chemotherapy are hallmarks of aggressive cancer; therefore, the development of approaches to simultaneously inhibit these two processes is highly desirable. Previous findings from our laboratory have demonstrated that cathepsin L plays a key role in the development of drug resistance in cancer, and that its inhibition reversed this phenomenon. The goal of the present study was to determine whether targeting cathepsin L would inhibit angiogenesis. For this, the effects of a specific cathepsin L inhibitor, Napsul-Ile-Trp-CHO (NSITC), were tested in vitro on endothelial cell proliferation and interaction with the extracellular matrix, and also in vivo, by measuring its effect on angiogenesis in the chick chorioallantoic membrane (CAM) and mouse matrigel models. The results indicated that NSITC readily inhibits the proliferation of endothelial cells by inducing cell cycle arrest at the G(0)/G(1) phase, and suppresses cell adhesion to different substrates. Investigation of the underlying mechanism(s) indicated that NSITC was able to reduce expression of the adhesion molecule alphaVbeta3 integrin, inhibit cathepsin L-mediated degradation of the extracellular matrix, and disrupt secretion of the pro-angiogenic factors fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF). NSITC demonstrated potent efficacy in inhibiting growth factor- and tumor mediated-angiogenesis in the CAM and mouse matrigel models of angiogenesis. The anti-angiogenic effects of NSITC resulted in inhibition of tumor growth in the CAM and in nude mouse xenograft models. Together, these findings provide evidence that cathepsin L plays an important role in angiogenesis and suggest that NSITC represents a potential drug for the treatment of aggressive cancer.
Asunto(s)
Inhibidores de la Angiogénesis/farmacología , Catepsina L/antagonistas & inhibidores , Dipéptidos/farmacología , Células Endoteliales/efectos de los fármacos , Inhibidores de Proteasas/farmacología , Animales , Adhesión Celular/efectos de los fármacos , Movimiento Celular/efectos de los fármacos , Embrión de Pollo , Células Endoteliales/citología , Células Endoteliales/enzimología , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Neovascularización Fisiológica/efectos de los fármacosRESUMEN
The organism's ability to regulate oxidative stress and metabolism is well recognized as a major determinant of longevity. While much research interest in this area is directed towards the study of genes that inhibit oxidative stress and/or improve metabolism, contribution to the aging process of genes with antagonistic effects on these two pathways is still less understood. The present study investigated the respective roles of the histone deacetylase Sirt1 and the thioredoxin binding protein TXNIP, two genes with opposite effects on oxidative stress and metabolism, in mediating the action of putative anti-aging interventions. Experiments were carried out in vitro and in vivo to determine the effect of proven, limited calorie availability, and unproven, resveratrol and dehydroepiandrosterone (DHEA), on the expression of Sirt1 and TXNIP. The results indicated that limited calorie availability consistently inhibited TXNIP in cancer and in normal cells including stem cells, however, it only slightly induced Sirt1expression in cancer cells. In contrast, resveratrol had a biphasic effect, and DHEA inhibited the expression of these two genes in a tissue specific manner, both in vitro and in vivo. Whereas all the three approaches tested inhibited TXNIP through the glycolytic pathway, DHEA acted by inhibiting G6PD and resveratrol through the activation of AMPK. In light of previous reports that Sirt1 induces AMPK-mediated signaling pathway, our findings point to the possibility of a negative relationship between Sirt1 and TXNIP that, if validated, can be exploited to improve the efficacy of putative anti-aging interventions.
Asunto(s)
Proteínas Portadoras/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/fisiología , Tiorredoxinas/metabolismo , Proteínas Quinasas Activadas por AMP/genética , Proteínas Quinasas Activadas por AMP/metabolismo , Animales , Proteínas Portadoras/genética , Células Cultivadas , Deshidroepiandrosterona/farmacología , Glucosa/farmacología , Humanos , Ratones , Ratas , Resveratrol , Sirtuina 1 , Estilbenos/farmacología , Tiorredoxinas/genéticaRESUMEN
Cathepsin L is a lysosomal enzyme thought to play a key role in malignant transformation. Recent work from our laboratory has demonstrated that this enzyme may also regulate cancer cell resistance to chemotherapy. The present study was undertaken to define the relevance of targeting cathepsin L in the suppression of drug resistance in vitro and in vivo and also to understand the mechanism(s) of its action. In vitro experiments indicated that cancer cell adaptation to increased amounts of doxorubicin over time was prevented in the presence of a cathepsin L inhibitor, suggesting that inhibition of this enzyme not only reverses but also prevents the development of drug resistance. The combination of the cathepsin L inhibitor with doxorubicin also strongly suppressed the proliferation of drug-resistant tumors in nude mice. An investigation of the underlying mechanism(s) led to the finding that the active form of this enzyme shuttles between the cytoplasm and nucleus. As a result, its inhibition stabilizes and enhances the availability of cytoplasmic and nuclear protein drug targets including estrogen receptor-alpha, Bcr-Abl, topoisomerase-IIalpha, histone deacetylase 1, and the androgen receptor. In support of this, the cellular response to doxorubicin, tamoxifen, imatinib, trichostatin A, and flutamide increased in the presence of the cathepsin L inhibitor. Together, these findings provided evidence for the potential role of cathepsin L as a target to suppress cancer resistance to chemotherapy and uncovered a novel mechanism by which protease inhibition-mediated drug target stabilization may enhance cellular visibility and, thus, susceptibility to anticancer agents.
Asunto(s)
Protocolos de Quimioterapia Combinada Antineoplásica/farmacología , Catepsinas/antagonistas & inhibidores , Resistencia a Antineoplásicos/efectos de los fármacos , Neuroblastoma/tratamiento farmacológico , Osteosarcoma/tratamiento farmacológico , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Animales , Antibióticos Antineoplásicos/administración & dosificación , Antígenos de Neoplasias/metabolismo , Catepsina L , Catepsinas/metabolismo , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Cisteína Endopeptidasas/metabolismo , Inhibidores de Cisteína Proteinasa/administración & dosificación , ADN-Topoisomerasas de Tipo II/metabolismo , Proteínas de Unión al ADN/metabolismo , Relación Dosis-Respuesta a Droga , Doxorrubicina/administración & dosificación , Humanos , Ratones , Ratones Desnudos , Neuroblastoma/enzimología , Neuroblastoma/patología , Osteosarcoma/enzimología , Osteosarcoma/patología , Estabilidad Proteica , Transporte de Proteínas , Factores de TiempoRESUMEN
The focus of this review is to discuss the hypothesis that justifies the use of dual antiplatelet therapy of aspirin and clopidogrel versus monotherapy with aspirin in arterial vascular disease. By analyzing the CLARITY-TIMI and COMMIT trials, the authors discuss the appropriate use of aspirin plus clopidogrel for patients suffering acute myocardial infarction. In contrast, in the CHARISMA trial, the combination was not justified in stable high-risk patients with documented coronary disease, cerebrovascular disease or symptomatic peripheral artery disease. In two additional cardiovascular studies, the CURE and the PCI-CURE trials, the benefit of the drug combination was evident in those patients who underwent percutaneous coronary intervention and coronary artery bypass grafting. Finally, two focused cerebrovascular studies, the CARESS and the MATCH trials, were analyzed. The CARESS trial demonstrated the clinical benefit of this combination in an acute clinical setting. However, the combination proved to be ineffective in the longer-term MATCH trial. It appears from these large clinical trials that the risk-benefit of dual antiplatelet therapy with aspirin and clopidogrel is justified in high-risk symptomatic patients but not in asymptomatic patients. The exact dose regimen and duration of combination therapy await definition and require careful assessment to optimize the anticoagulant benefit, while minimizing the hemorrhagic risk.