RESUMEN
Follicular lymphoma (FL) cells are malignant counterparts of germinal centre (GC) B cells. Microenvironment of FL B cells has an important role in the progression of FL and might also have an impact on the treatment of FL. CD40 is an important mediator of microenvironmental survival signals in GCs. Here we studied responses of CD40 signalling on TRAIL-, dexamethasone- and doxorubicin-induced apoptosis in three human FL cell lines. In two of the FL cell lines, CD40 protected cells from apoptosis which was entirely dependent on the activation of NF-kappaB. In one of the FL cell lines, CD40 induced apoptosis itself. However, inhibition of NF-kappaB induced apoptosis in all three FL cell lines. Therefore, our results indicate that inhibitors of NF-kappaB or critical downstream anti-apoptotic targets of NF-kappaB instead of blocking CD40 antibodies in combination with TRAIL or other cytotoxic agents should be considered in the treatment of FL in order to prevent the protective effect of the microenvironment.
Asunto(s)
Apoptosis/inmunología , Antígenos CD40/inmunología , Quinasa I-kappa B/inmunología , Linfoma Folicular/inmunología , FN-kappa B/inmunología , Antibióticos Antineoplásicos/farmacología , Anticuerpos/farmacología , Antioxidantes/farmacología , Apoptosis/efectos de los fármacos , Proteína Reguladora de Apoptosis Similar a CASP8 y FADD/inmunología , Proteína Reguladora de Apoptosis Similar a CASP8 y FADD/metabolismo , Antígenos CD40/agonistas , Antígenos CD40/metabolismo , Antígenos CD40/farmacología , Línea Celular Tumoral , Dexametasona/farmacología , Doxorrubicina/farmacología , Glucocorticoides/farmacología , Humanos , Quinasa I-kappa B/antagonistas & inhibidores , Quinasa I-kappa B/metabolismo , Imidazoles/farmacología , Linfoma Folicular/metabolismo , FN-kappa B/antagonistas & inhibidores , FN-kappa B/metabolismo , Prolina/análogos & derivados , Prolina/farmacología , Quinoxalinas/farmacología , Transducción de Señal/efectos de los fármacos , Transducción de Señal/inmunología , Ligando Inductor de Apoptosis Relacionado con TNF/farmacología , Tiocarbamatos/farmacología , Proteína bcl-X/inmunología , Proteína bcl-X/metabolismoRESUMEN
During the germinal centre reaction (GC), B cells with non-functional or self-reactive antigen receptors are negatively selected by apoptosis to generate B cell repertoire with appropriate antigen specificities. We studied the molecular mechanism of Fas/CD95- and B cell receptor (BCR)-induced apoptosis to shed light on the signalling events involved in the negative selection of GC B cells. As an experimental model, we used human follicular lymphoma (FL) cell line HF1A3, which originates from a GC B cell, and transfected HF1A3 cell lines overexpressing Bcl-x(L), c-FLIP(long) or dominant negative (DN) caspase-9. Fas-induced apoptosis was dependent on the caspase-8 activation, since the overexpression of c-FLIP(long), a natural inhibitor of caspase-8 activation, blocked apoptosis induced by Fas. In contrast, caspase-9 activation was not involved in Fas-induced apoptosis. BCR-induced apoptosis showed the typical characteristics of mitochondria-dependent (intrinsic) apoptosis. Firstly, the activation of caspase-9 was involved in BCR-induced DNA fragmentation, while caspase-8 showed only marginal role. Secondly, overexpression of Bcl-x(L) could block all apoptotic changes induced by BCR. As a novel finding, we demonstrate that caspase-9 can enhance the cytochrome-c release and collapse of mitochondrial membrane potential (DeltaPsi(m)) during BCR-induced apoptosis. The requirement of different signalling pathways in apoptosis induced by BCR and Fas may be relevant, since Fas- and BCR-induced apoptosis can thus be regulated independently, and targeted to different subsets of GC B cells.
Asunto(s)
Apoptosis/inmunología , Linfocitos B/inmunología , Proteína Reguladora de Apoptosis Similar a CASP8 y FADD/inmunología , Caspasa 9/inmunología , Receptores de Antígenos de Linfocitos B/inmunología , Proteína bcl-X/inmunología , Clorometilcetonas de Aminoácidos/farmacología , Anticuerpos Monoclonales/farmacología , Apoptosis/efectos de los fármacos , Linfocitos B/efectos de los fármacos , Linfocitos B/metabolismo , Proteína Reguladora de Apoptosis Similar a CASP8 y FADD/metabolismo , Caspasa 8/inmunología , Caspasa 8/metabolismo , Caspasa 9/metabolismo , Inhibidores de Caspasas , Línea Celular Tumoral , Inhibidores de Cisteína Proteinasa/farmacología , Citocromos c/inmunología , Citocromos c/metabolismo , Fragmentación del ADN/efectos de los fármacos , Retroalimentación Fisiológica , Centro Germinal/inmunología , Centro Germinal/metabolismo , Humanos , Factores Inmunológicos/farmacología , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Potencial de la Membrana Mitocondrial/fisiología , Mitocondrias/efectos de los fármacos , Mitocondrias/enzimología , Mitocondrias/inmunología , Oligopéptidos/farmacología , Receptores de Antígenos de Linfocitos B/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/inmunología , Proteína bcl-X/metabolismo , Receptor fas/agonistas , Receptor fas/inmunología , Receptor fas/metabolismoRESUMEN
Urokinase-type plasminogen activator receptor (uPAR) is functionally a pleiotropic mediator involved in cell adhesion, proliferation, differentiation and migration as well as in matrix degradation, apoptosis, and angiogenesis in cancer tissue. Comparable cellular alterations occur in the brain during post-injury tissue repair. As the first step to assess the role of uPAR in brain tissue remodeling, we tested a hypothesis that uPAR expression is altered in the hippocampus during epilepsy-related circuitry reorganization. Epileptogenesis was triggered by inducing status epilepticus (SE) with electrical stimulation of the amygdala in rats. To monitor the development of SE and the occurrence of spontaneous seizures animals were continuously video-EEG monitored until sacrificed (1, 2, 4 or 14 days after SE). The hippocampal expression of uPAR was studied with real time qPCR and immunohistochemistry. Double-immunohistochemistry and confocal microscopy were used to investigate the expression of uPAR in astrocytes, microglia and neurons. We show that in the normal hippocampus the expression of uPAR was low and confined to small population of astrocytes and interneurons. In animals undergoing SE, uPAR expression increased dramatically, peaking at 1 and 4 days after SE. According to double-immunohistochemistry, uPAR was highly expressed in parvalbumin positive interneurons in the hippocampus and dentate gyrus, and in a subgroup of somatostatin and neuropeptide Y positive hilar interneurons. Increased uPAR expression during post-injury phase supports its contribution to tissue remodeling in the brain. Surviving hilar interneurons that are known to be denervated due to loss of afferent inputs in post-SE brain provide a target for future studies to investigate the contribution of uPAR in reinnervation of these cells, and to identify the signaling cascades that mediate the effects of uPAR.
Asunto(s)
Epilepsia/metabolismo , Hipocampo/metabolismo , Degeneración Nerviosa/metabolismo , Receptores del Activador de Plasminógeno Tipo Uroquinasa/metabolismo , Animales , Astrocitos/metabolismo , Línea Celular , Modelos Animales de Enfermedad , Estimulación Eléctrica , Epilepsia/patología , Epilepsia/fisiopatología , Regulación de la Expresión Génica/fisiología , Hipocampo/fisiopatología , Humanos , Inmunohistoquímica , Interneuronas/metabolismo , Excitación Neurológica , Masculino , Degeneración Nerviosa/etiología , Degeneración Nerviosa/fisiopatología , Neuropéptido Y/metabolismo , Parvalbúminas/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores del Activador de Plasminógeno Tipo Uroquinasa/genética , Transducción de Señal/fisiología , Somatostatina/metabolismo , Regulación hacia Arriba/fisiologíaRESUMEN
Cancer suicide gene therapy based on herpes simplex virus type I thymidine kinase (HSV-TK) and ganciclovir (GCV) suffers from the lack of efficacy in clinical use, which is mostly due to low gene-transfer efficiency and absence of bystander effect in tumors. We have previously demonstrated the enhancement of GCV cytotoxicity by fusing the HSV-TK with the cell penetrating peptide from HIV-1 transactivator protein transduction domain (TAT PTD). Despite the earlier promising results, we found that the triple fusion protein HIV-1 transactivator protein transduction domain-thymidine kinase suicide gene-green fluorescent protein marker gene (TAT-TK-GFP) increased GCV cytotoxicity only in 3/12 of different human tumor cell lines. Extended GCV exposure enhanced the cytotoxic effect of HSV-TK/GCV gene therapy, but the difference between TK-GFP and TAT-TK-GFP was not statistically significant. The modest improvement on cell killing mediated by TAT PTD in Chinese hamster ovary cells appeared to be associated with cell-surface heparan sulfate proteoglycan (HSPG) composition. However, TAT-mediated increased cell death did not correlate with the density of cell-surface HSPG expression in different tumor cell lines. In conclusion, although some degree of enhancement by TAT was shown in certain tumor cells in vitro, it is unlikely that TAT peptide linked to a suicide protein could be a useful booster of in vivo gene therapy trials.
Asunto(s)
Ganciclovir/uso terapéutico , Terapia Genética/métodos , Herpesvirus Humano 1/genética , Neoplasias/genética , Neoplasias/terapia , Fragmentos de Péptidos/uso terapéutico , Timidina Quinasa/genética , Productos del Gen tat del Virus de la Inmunodeficiencia Humana/uso terapéutico , Animales , Antivirales/uso terapéutico , Células CHO , Muerte Celular/efectos de los fármacos , Cricetinae , Cricetulus , Humanos , Timidina Quinasa/uso terapéutico , Productos del Gen tat del Virus de la Inmunodeficiencia Humana/químicaRESUMEN
Using an absorption cell, we measured the Doppler shifts of the interstellar hydrogen resonance glow to show the direction of the neutral hydrogen flow as it enters the inner heliosphere. The neutral hydrogen flow is found to be deflected relative to the helium flow by about 4 degrees . The most likely explanation of this deflection is a distortion of the heliosphere under the action of an ambient interstellar magnetic field. In this case, the helium flow vector and the hydrogen flow vector constrain the direction of the magnetic field and act as an interstellar magnetic compass.
RESUMEN
The atmospheric air pollutant ozone (O3) is one of the environmental stresses that induce formation of reactive oxygen species (ROS) in plants. Previously, the toxicity of O3 has been believed to be a result of ROS formation from O3-degradation. Recently, however, it has been shown that O3 induces active ROS production, which suggests that O3-responses may be mechanistically similar to pathogen-induced responses and that O3-damage could be a result of deleterious firing by the ROS of pathways normally associated with the HR. The subcellular localization of O3-induced H2O2 production was studied in birch (Betula pendula). O3 induced H2O2 accumulation first on the plasma membrane and cell wall. Experiments with inhibitors of possible sources for H2O2 in the cell wall suggested that both NADPH-dependent superoxide synthase and the cell wall peroxidases are involved in this H2O2 production. The H2O2 production continued in the cytoplasm, mitochondria and peroxisomes when the O3-exposure was over, but not in chloroplasts. The timing of mitochondrial H2O2 accumulation coincided with the first symptoms of visible damage and, at the same time, the mitochondria showed disintegration of the matrix. These responses may not be directly connected with defense against oxidative stress, but may rather indicate changes in oxidative balance within the cells that affect mitochondrial metabolism and the homeostasis of the whole cell, possibly leading into induction of programmed cell death.
Asunto(s)
Contaminantes Atmosféricos/toxicidad , Peróxido de Hidrógeno/metabolismo , Ozono/toxicidad , Hojas de la Planta/metabolismo , Árboles/metabolismo , Microscopía Electrónica , Hojas de la Planta/ultraestructura , Especies Reactivas de Oxígeno/metabolismoRESUMEN
A mission to Mars including two Small Stations, two Penetrators and an Orbiter was launched at Baikonur, Kazakhstan, on 16 November 1996. This was called the Mars-96 mission. The Small Stations were expected to land in September 1997 (Ls approximately 178 degrees), nominally to Amazonis-Arcadia region on locations (33 N, 169.4 W) and (37.6 N, 161.9 W). The fourth stage of the Mars-96 launcher malfunctioned and hence the mission was lost. However, the state of the art concept of the Small Station can be applied to future Martian lander missions. Also, from the manufacturing and performance point of view, the Mars-96 Small Station could be built as such at low cost, and be fairly easily accommodated on almost any forthcoming Martian mission. This is primarily due to the very simple interface between the Small Station and the spacecraft. The Small Station is a sophisticated piece of equipment. With the total available power of approximately 400 mW the Station successfully supports an ambitious scientific program. The Station accommodates a panoramic camera, an alpha-proton-x-ray spectrometer, a seismometer, a magnetometer, an oxidant instrument, equipment for meteorological observations, and sensors for atmospheric measurement during the descent phase, including images taken by a descent phase camera. The total mass of the Small Station with payload on the Martian surface, including the airbags, is only 32 kg. Lander observations on the surface of Mars combined with data from Orbiter instruments will shed light on the contemporary Mars and its evolution. As in the Mars-96 mission, specific science goals could be exploration of the interior and surface of Mars, investigation of the structure and dynamics of the atmosphere, the role of water and other materials containing volatiles and in situ studies of the atmospheric boundary layer processes. To achieve the scientific goals of the mission the lander should carry a versatile set of instruments. The Small Station accommodates devices for atmospheric measurements, geophysical and geochemical studies of the Martian surface and interior, and cameras for descent phase and panoramic views. These instruments would be able to contribute remarkably to the process of solving some of the scientific puzzles of Mars.