Involvement of miRNAs in the differentiation of human glioblastoma multiforme stem-like cells

Glioblastoma multiforme (GBM)-initiating cells (GICs) represent a tumor subpopulation with neural stem cell-like properties that is responsible for the development, progression and therapeutic resistance of human GBM. We have recently shown that blockade of NFκB pathway promotes terminal differentiation and senescence of GICs both in vitro and in vivo, indicating that induction of differentiation may be a potential therapeutic strategy for GBM. MicroRNAs have been implicated in the pathogenesis of GBM, but a high-throughput analysis of their role in GIC differentiation has not been reported. We have established human GIC cell lines that can be efficiently differentiated into cells expressing astrocytic and neuronal lineage markers. Using this in vitro system, a microarray-based high-throughput analysis to determine global expression changes of microRNAs during differentiation of GICs was performed. A number of changes in the levels of microRNAs were detected in differentiating GICs, including over-expression of hsa-miR-21, hsa-miR-29a, hsa-miR-29b, hsa-miR-221 and hsa-miR-222, and down-regulation of hsa-miR-93 and hsa-miR-106a. Functional studies showed that miR-21 over-expression in GICs induced comparable cell differentiation features and targeted SPRY1 mRNA, which encodes for a negative regulator of neural stem-cell differentiation. In addition, miR-221 and miR-222 inhibition in differentiated cells restored the expression of stem cell markers while reducing differentiation markers. Finally, miR-29a and miR-29b targeted MCL1 mRNA in GICs and increased apoptosis. Our study uncovers the microRNA dynamic expression changes occurring during differentiation of GICs, and identifies miR-21 and miR-221/222 as key regulators of this process

A cyclin-D1 interaction with BAX underlies its oncogenic role and potential as a therapeutic target in mantle cell lymphoma

The chromosomal translocation t(11;14)(q13;q32) leading to cyclin-D1 overexpression plays an essential role in the development of mantle cell lymphoma (MCL), an aggressive tumor that remains incurable with current treatment strategies. Cyclin-D1 has been postulated as an effective therapeutic target, but the evaluation of this target has been hampered by our incomplete understanding of its oncogenic functions and by the lack of valid MCL murine models. To address these issues, we generated a cyclin-D1-driven mouse model in which cyclin-D1 expression can be regulated externally. These mice developed cyclin-D1-expressing lymphomas capable of recapitulating features of human MCL. We found that cyclin-D1 inactivation was not sufficient to induce lymphoma regression in vivo; however, using a combination of in vitro and in vivo assays, we identified a novel prosurvival cyclin-D1 function in MCL cells. Specifically, we found that cyclin-D1, besides increasing cell proliferation through deregulation of the cell cycle at the G(1)-S transition, sequestrates the proapoptotic protein BAX in the cytoplasm, thereby favoring BCL2's antiapoptotic function. Accordingly, cyclin-D1 inhibition sensitized the lymphoma cells to apoptosis through BAX release. Thus, genetic or pharmacologic targeting of cyclin-D1 combined with a proapoptotic BH3 mimetic synergistically killed the cyclin-D1-expressing murine lymphomas, human MCL cell lines, and primary lymphoma cells. Our study identifies a role of cyclin-D1 in deregulating apoptosis in MCL cells, and highlights the potential benefit of simultaneously targeting cyclin-D1 and survival pathways in patients with MCL. This effective combination therapy also might be exploited in other cyclin-D1-expressing tumors

Expression of MALT1 oncogene in hematopoietic stem/progenitor cells recapitulates the pathogenesis of human lymphoma in mice

Chromosomal translocations involving the MALT1 gene are hallmarks of mucosa-associated lymphoid tissue (MALT) lymphoma. To date, targeting these translocations to mouse B cells has failed to reproduce human disease. Here, we induced MALT1 expression in mouse Sca1(+)Lin(-) hematopoietic stem/progenitor cells, which showed NF-κB activation and early lymphoid priming, being selectively skewed toward B-cell differentiation. These cells accumulated in extranodal tissues and gave rise to clonal tumors recapitulating the principal clinical, biological, and molecular genetic features of MALT lymphoma. Deletion of p53 gene accelerated tumor onset and induced transformation of MALT lymphoma to activated B-cell diffuse large-cell lymphoma (ABC-DLBCL). Treatment of MALT1-induced lymphomas with a specific inhibitor of MALT1 proteolytic activity decreased cell viability, indicating that endogenous Malt1 signaling was required for tumor cell survival. Our study shows that human-like lymphomas can be modeled in mice by targeting MALT1 expression to hematopoietic stem/progenitor cells, demonstrating the oncogenic role of MALT1 in lymphomagenesis. Furthermore, this work establishes a molecular link between MALT lymphoma and ABC-DLBCL, and provides mouse models to test MALT1 inhibitors. Finally, our results suggest that hematopoietic stem/progenitor cells may be involved in the pathogenesis of human mature B-cell lymphomas

Nota corta: Actividad antagonista de Bacillus subtilis sobre Xanthomonas campestris pv. Glycines en condiciones controladas

Xanthomonas campestris pv. glycines (Nakano) Dye is the causal agent of bacterial pustule in soybean (Glycinemax L.) Merrill. Two tests were carried out using 175 bacteria isolated in a previous work from the soybean leafletsor phyllosphere: the first one for susceptibility to three antimicrobial agents (penicillin, streptomycin and rifampicin)applied at two different doses (20 and 100 µg ml-1), and the second one for antagonism towards X. campestris. Eighteenbacterial isolates (10.3%) were resistant to penicillin and five (2.8%) to streptomycin at 100 µg ml-1; only 2% ofthe phyllosphere bacteria were resistant to rifampicin at 20 µg ml-1. Isolate 210, identified as Bacillus subtilis, was resistantto rifampicin at 20 µg ml-1, showed the highest degree of antibiosis against the pathogen and was further testedfor antagonism against the pathogenic bacteria under greenhouse conditions. In the inoculation study, treatmentof soybean leaf surfaces with B. subtilis 210 72 h before the inoculation with the pathogenic bacteria, reduced thenumber of lesions by X. campestris. There were significant differences with other treatments (PXanthomonas campestris pv. glycines (Nakano) Dye es el agente causal de la pústula bacteriana de la soja (Glycine max L.) Merrill. Se determinó la susceptibilidad in vitro a tres agentes antimicrobianos (penicilina, estreptomicina y rifampicina) aplicados a dos dosis diferentes (20 y 100 micro g ml sup(-1)) y la capacidad para inhibir Xanthomonas campestris de 175 bacterias aisladas de la filosfera de soja en un trabajo anterior. Dieciocho cepas bacterianas (10.3% ) fueron resistentes a penicilina y cinco a estreptomicina (2.8% ) en la dosis de 100 micro g ml sup(-1), pero sólo un 2% fueron resistentes a rifampicina en la dosis de 20 micro g ml sup(-1). El aislado 210, identificado como Bacillus subtilis, fue resistente a rifampicina en la dosis de 20 micro g ml sup (-1) y exhibió el mayor grado de antibiosis contra el patógeno (...

Antagonistic activity by "Bacillus subtilis" against "Xanthomonas campestris" pv. "glycines" aunder controlled conditions: Short communication

Xanthomonas campestris pv. glycines (Nakano) Dye es el agente causal de la pústula bacteriana de la soja (Glycine max L.) Merrill. Se determinó la susceptibilidad in vitro a tres agentes antimicrobianos (penicilina, estreptomicina y rifampicina) aplicados a dos dosis diferentes (20 y 100 mg ml-1) y la capacidad para inhibir Xanthomonas campestris de 175 bacterias aisladas de la filosfera de soja en un trabajo anterior. Dieciocho cepas bacterianas (10,3%) fueron resistentes a penicilina y cinco a estreptomicina (2,8%) en la dosis de 100 mg ml-1, pero sólo un 2% fueron resistentes a rifampicina en la dosis de 20 mg ml-1. El aislado 210, identificado como Bacillus subtilis, fue resistente a rifampicina en la dosis de 20 mg ml-1 y exhibió el mayor grado de antibiosis contra el patógeno. Cuando el efecto antagónico del bacilo esporulado fue estudiado en invernadero, se observó que aplicado 72 h antes de la inoculación de la cepa del patógeno, redujo el número de lesiones producidas por Xanthomonas campestris en las hojas de soja. La comparación estadística con otros tratamientos dio diferencias significativas (P<0,05). Los resultados de este trabajo, aunque preliminares, indican las posibilidades de B. subtilis 210 como agente antagonista para el control de la pústula bacteriana de la soj

Mus musculus lesions inoculated with Mycobacterium phlei, Mycobacterium kansasii and Mycobacterium fortuitum isolated from soil of La Pampa Province (R. Argentina)

The study objective was to determine the capacity of originate macroscopic and microscopic lesions of nine atypical mycobacteria inoculated in albino rats. The mycobacteria were isolated from farms soil samples at different places from La Pampa province (Argentina). It was investigated the three most frequent species (M. fortuitum, M. phlei and M. kansasii). The animals were endovenously inoculated with 1 mg of bacteria/ml-1 of fresh culture and kept in a restricted area during 60 days. After euthanasia, samples from different organs, for bacteriologic and histopathologic studies, were collected. M. phlei and M. kansasii showed lesions resemble to that produced by M. tuberculosis or M. bovis, whereas M. fortuitum did not show lesions in the animal model descript in this study. It is necessary to value other atypical mycobacterium isolated from soil and other inoculation ways in order to assist in clarifying the differential diagnosis in tuberculosis and other granulomatose diseases.Fil: Oriani, D.S. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias. Departamento de Epizootiología y Salud Pública. La Pampa, ArgentinaFil: Sagardoy, M.A. Universidad Nacional del Sur. Departamento de Agronomía. Buenos Aires, ArgentinaEl objetivo de este trabajo fue determinar la capacidad para producir lesiones macro y microscópicas de nueve aislamientos de micobacterias no tuberculosas (MNT) cuando eran inoculadas en ratones albinos (Mus musculus). Las micobacterias fueron aisladas de muestras de suelos destinados a la agricultura y ganadería de la provincia de La Pampa, Argentina. Se investigaron tres especies ambientales (M. fortuitum, M. phlei y M. kansasii) que eran dominantes en los suelos estudiados. Los animales fueron inoculados por vía endovenosa, con una suspensión de cultivos frescos de MNT, equivalente a 1 mg de bacterias mL1. Los animales se mantuvieron en un área restringida durante 60 días, en ese momento se les efectuó la eutanasia y la necropsia, recolectando órganos para realizar estudios bacteriológicos e histopatológicos. Las cepas de M. phlei y M. kansasii inoculadas produjeron lesiones en los ratones similares a las producidas por M. tuberculosis y/o bovis, mientras que M. fortuitum no desarrollo patogenicidad en el modelo animal utilizado bajo las condiciones en que se realizó este estudio. Es necesario continuar valorando otras micobacterias ambientales aisladas de suelos y otras vías de inoculación contribuyendo a colaborar en el diagnostico diferencial de la tuberculosis y las enfermedades granulomatosas

Susceptibility of Mycobacterium fortuitum, Mycobacterium phlei and Mycobacterium kansasii to three different germicide solutions

An investigation was carried out to measure the in vitro susceptibility of opportunistic mycobacteria to three antimicrobial agents. Field strains of nontuberculous mycobacteria were obtained of soil samples from La Pampa province (Argentina). Strains of the following species were tested: Mycobacterium fortuitum, M. phlei and M. kansasii. The antimicrobial agents were: 2% and 4% formaldehyde solutions, 3% and 5% phenol solutions and 70% alcohol solution. At 20o C, suspensions of the test strains were exposed to the germicides and samples were taken at defined intervals (25 min and 45 min) to determine the concentration of survivors. From these data, the decimal reduction times (D) were calculated for each test strain. The results obtained indicated that the nontuberculous mycobacteria were resistant to formaldehyde 2% during 25 min. The D values found revealed considerable differences in the chemical susceptibilities of the test strains. However, all the tested strains were susceptible to formaldehyde 4%, phenol solutions, and alcohol solution 70%. It is necessary to continue evaluating other germicide agents and their effects on Mycobacterium bovis in order to find effective disinfectants for animal waters and field facilities, thus contributing to the control of tuberculosis in cattle.Fil: Oriani, D.S. Universidad Nacional de La Pampa. Facultad de Ciencias Veterinarias. Departamento de Epizootiología y Salud Pública. La Pampa, ArgentinaFil: Sagardoy, M.A. Universidad Nacional del Sur. Departamento de Agronomía. Buenos Aires, ArgentinaEl objetivo de este trabajo fue evaluar la susceptibilidad in vitro de nueve micobacterias no tuberculosas frente a tres agentes antimicrobianos de amplio uso. Las micobacterias fueron aisladas de muestras de suelos de la provincia de La Pampa (Argentina). Se utilizaron tres especies ambientales (Mycobacterium fortuitum, M. phlei y M. kansasii), tres agentes químicos (formaldehído 2% y 4 %, fenol 3% y 5% y alcohol 70%) y dos tiempos de exposición (25 min y 45 min). Las micobacterias eran sólo resistentes al formaldehído 2% después de 25 min de exposición. Los valores de reducción decimal (D) calculados con ese tratamiento mostraron que las cepas tenían grandes diferencias de susceptibilidad al formaldehído 2%. Sin embargo, todas las micobacterias fueron eliminadas cuando se usó formaldehído 4%, fenol 3% y 5 % y alcohol 70% (25 min). Es necesario continuar valorando otros agentes germicidas y sus efectos frente a Mycobacterium bovis con el objeto de encontrar desinfectantes efectivos para instalaciones y aguadas, contribuyendo de esta forma en el control de la tuberculosis de los rodeos

Sporulation at minimum specific growth rate in Aspergillus nidulans chemostat culture predicted using protein synthesis efficiency estimations

Ribosomal efficiency (RE) estimates provide a quantitative descriptor of intrinsic growth rate of cell populations using readily-obtainable experimental data. In Aspergillus nidulans chemostat cultures, RE increased linearly with growth rate over the range 25-60% of maximum growth rate (mu(max)) consistent with increasing ribosomal usage with increased growth rate. Above 60%, RE did not in crease significantly, suggesting that all ribosomes were functional at 60% of mu(max), further increases in growth rate, presumably resulting from increased polypeptide chain elongation rate. Extrapolating the linear part of the RE/growth rate curve predicted zero RE at a growth rate of 0.04 h(-1). Chemostat steady state cultures at 0.04 h(-1) contained spores (conidia), apparently undergoing a continuous sporulation/germination cycle. We propose that the RE estimates provide a means of predicting the value of minimum specific growth rate (mu(min)) below which net growth cannot take place