RESUMEN
Although the development of bone metastasis is a major detrimental event in prostate cancer, the molecular mechanisms responsible for bone homing and destruction remain largely unknown. Here we show that loss of miR-15 and miR-16 in cooperation with increased miR-21 expression promote prostate cancer spreading and bone lesions. This combination of microRNA endows bone-metastatic potential to prostate cancer cells. Concomitant loss of miR-15/miR-16 and gain of miR-21 aberrantly activate TGF-ß and Hedgehog signaling, that mediate local invasion, distant bone marrow colonization and osteolysis by prostate cancer cells. These findings establish a new molecular circuitry for prostate cancer metastasis that was validated in patients' cohorts. Our data indicate a network of biomarkers and druggable pathways to improve patient treatment.
Asunto(s)
Biomarcadores de Tumor/biosíntesis , Neoplasias Óseas/genética , MicroARNs/biosíntesis , Neoplasias de la Próstata/genética , Animales , Neoplasias Óseas/patología , Neoplasias Óseas/secundario , Línea Celular Tumoral , Transición Epitelial-Mesenquimal/genética , Regulación Neoplásica de la Expresión Génica , Proteínas Hedgehog/biosíntesis , Humanos , Masculino , MicroARNs/genética , Invasividad Neoplásica/genética , Neoplasias de la Próstata/patología , Transducción de Señal/genética , Factor de Crecimiento Transformador beta/biosíntesisRESUMEN
Stemness was recently depicted as a dynamic condition in normal and tumor cells. We found that the embryonic protein Cripto-1 (CR1) was expressed by normal stem cells at the bottom of colonic crypts and by cancer stem cells (CSCs) in colorectal tumor tissues. CR1-positive populations isolated from patient-derived tumor spheroids exhibited increased clonogenic capacity and expression of stem-cell-related genes. CR1 expression in tumor spheroids was variable over time, being subject to a complex regulation of the intracellular, surface and secreted protein, which was related to changes of the clonogenic capacity at the population level. CR1 silencing induced CSC growth arrest in vitro with a concomitant decrease of Src/Akt signaling, while in vivo it inhibited the growth of CSC-derived tumor xenografts and reduced CSC numbers. Importantly, CR1 silencing in established xenografts through an inducible expression system decreased CSC growth in both primary and metastatic tumors, indicating an essential role of CR1 in the regulation the CSC compartment. These results point to CR1 as a novel and dynamically regulated effector of stem cell functions in colorectal cancer.
Asunto(s)
Neoplasias Colorrectales/metabolismo , Proteínas Ligadas a GPI/metabolismo , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Proteínas de Neoplasias/metabolismo , Células Madre Neoplásicas/metabolismo , Animales , Neoplasias Colorrectales/fisiopatología , Femenino , Proteínas Ligadas a GPI/genética , Proteínas Ligadas a GPI/fisiología , Regulación Neoplásica de la Expresión Génica , Genes src , Humanos , Péptidos y Proteínas de Señalización Intercelular/genética , Péptidos y Proteínas de Señalización Intercelular/fisiología , Ratones , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/fisiología , Células Madre Neoplásicas/fisiología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Esferoides Celulares , Células Tumorales CultivadasRESUMEN
As part of the scientific tasks coordinated throughout The 'New Methodologies and Protocols of Forensic Identification by Craniofacial Superimposition (MEPROCS)' project, the current study aims to analyse the performance of a diverse set of CFS methodologies and the corresponding technical approaches when dealing with a common dataset of real-world cases. Thus, a multiple-lab study on craniofacial superimposition has been carried out for the first time. In particular, 26 participants from 17 different institutions in 13 countries were asked to deal with 14 identification scenarios, some of them involving the comparison of multiple candidates and unknown skulls. In total, 60 craniofacial superimposition problems divided in two set of females and males. Each participant follow her/his own methodology and employed her/his particular technological means. For each single case they were asked to report the final identification decision (either positive or negative) along with the rationale supporting the decision and at least one image illustrating the overlay/superimposition outcome. This study is expected to provide important insights to better understand the most convenient characteristics of every method included in this study.
Asunto(s)
Toma de Decisiones , Cara/anatomía & histología , Antropología Forense/métodos , Cráneo/anatomía & histología , Conjuntos de Datos como Asunto , Femenino , Humanos , Imagenología Tridimensional , Masculino , Fotograbar , Reproducibilidad de los Resultados , Programas InformáticosRESUMEN
Lung cancer is the most common cause of cancer-related mortality worldwide, urging the discovery of novel molecular targets and therapeutic strategies. Stem cells have been recently isolated from non-small cell lung cancer (NSCLC), thus allowing the investigation of molecular pathways specifically active in the tumorigenic population. We have found that Bcl-XL is constantly expressed by lung cancer stem cells (LCSCs) and has a prominent role in regulating LCSC survival. Whereas chemotherapeutic agents were scarcely effective against LCSC, the small molecule Bcl-2/Bcl-XL inhibitor ABT-737, but not the selective Bcl-2 inhibitor ABT-199, induced LCSC death at nanomolar concentrations. Differently from gemcitabine, which preferentially eliminated proliferating LCSC, ABT-737 had an increased cytotoxic activity in vitro towards quiescent/slow-proliferating LCSC, which expressed high levels of Bcl-XL. In vivo, ABT-737 as a single agent was able to inhibit the growth of LCSC-derived xenografts and to reduce cancer stem cell content in treated tumors. Altogether, these results indicate that quiescent/slow-proliferating LCSC strongly depend on Bcl-XL for their survival and indicate Bcl-XL inhibition as a potential therapeutic avenue in NSCLC.
Asunto(s)
Antineoplásicos/farmacología , Compuestos de Bifenilo/farmacología , Carcinoma de Pulmón de Células no Pequeñas/patología , Neoplasias Pulmonares/patología , Células Madre Neoplásicas/fisiología , Nitrofenoles/farmacología , Sulfonamidas/farmacología , Proteína bcl-X/antagonistas & inhibidores , Animales , Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Línea Celular Tumoral , Proliferación Celular , Supervivencia Celular/efectos de los fármacos , Femenino , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Neoplasias Pulmonares/metabolismo , Ratones Endogámicos NOD , Ratones SCID , Células Madre Neoplásicas/efectos de los fármacos , Piperazinas/farmacología , Carga Tumoral , Ensayos Antitumor por Modelo de Xenoinjerto , Proteína bcl-X/metabolismoRESUMEN
Prostate cancer is one of the leading causes of cancer-related death in men. Despite significant advances in prostate cancer diagnosis and management, the molecular events involved in the transformation of normal prostate cells into cancer cells have not been fully understood. It is generally accepted that prostate cancer derives from the basal compartment while expressing luminal markers. We investigated whether downregulation of the basal protein B-cell translocation gene 2 (BTG2) is implicated in prostate cancer transformation and progression. Here we show that BTG2 loss can shift normal prostate basal cells towards luminal markers expression, a phenotype also accompanied by the appearance of epithelial-mesenchymal transition (EMT) traits. We also show that the overexpression of microRNA (miR)-21 suppresses BTG2 levels and promotes the acquisition of luminal markers and EMT in prostate cells. Furthermore, by using an innovative lentiviral vector able to compete with endogenous mRNA through the overexpression of the 3'-untranslated region of BTG2, we demonstrate that in prostate tumor cells, the levels of luminal and EMT markers can be reduced by derepression of BTG2 from microRNA-mediated control. Finally, we show that the loss of BTG2 expression confers to non-tumorigenic prostate cells ability to grow in an orthotopic murine model, thus demonstrating the central role of BTG2 downregulaton in prostate cancer biology.
Asunto(s)
Biomarcadores de Tumor/genética , Transformación Celular Neoplásica/patología , Transición Epitelial-Mesenquimal , Proteínas Inmediatas-Precoces/metabolismo , MicroARNs/genética , Próstata/patología , Neoplasias de la Próstata/patología , Proteínas Supresoras de Tumor/metabolismo , Animales , Apoptosis , Biomarcadores de Tumor/metabolismo , Western Blotting , Línea Celular Tumoral , Proliferación Celular , Células Cultivadas , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica , Humanos , Proteínas Inmediatas-Precoces/antagonistas & inhibidores , Proteínas Inmediatas-Precoces/genética , Masculino , Ratones , Próstata/metabolismo , Neoplasias de la Próstata/genética , Neoplasias de la Próstata/metabolismo , ARN Mensajero/genética , ARN Interferente Pequeño/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Proteínas Supresoras de Tumor/antagonistas & inhibidores , Proteínas Supresoras de Tumor/genéticaRESUMEN
Cancer stem cell (SC) chemoresistance may be responsible for the poor clinical outcome of non-small-cell lung cancer (NSCLC) patients. In order to identify the molecular events that contribute to NSCLC chemoresistance, we investigated the DNA damage response in SCs derived from NSCLC patients. We found that after exposure to chemotherapeutic drugs NSCLC-SCs undergo cell cycle arrest, thus allowing DNA damage repair and subsequent cell survival. Activation of the DNA damage checkpoint protein kinase (Chk) 1 was the earliest and most significant event detected in NSCLC-SCs treated with chemotherapy, independently of their p53 status. In contrast, a weak Chk1 activation was found in differentiated NSCLC cells, corresponding to an increased sensitivity to chemotherapeutic drugs as compared with their undifferentiated counterparts. The use of Chk1 inhibitors in combination with chemotherapy dramatically reduced NSCLC-SC survival in vitro by inducing premature cell cycle progression and mitotic catastrophe. Consistently, the co-administration of the Chk1 inhibitor AZD7762 and chemotherapy abrogated tumor growth in vivo, whereas chemotherapy alone was scarcely effective. Such increased efficacy in the combined use of Chk1 inhibitors and chemotherapy was associated with a significant reduction of NSCLC-SCs in mouse xenografts. Taken together, these observations support the clinical evaluation of Chk1 inhibitors in combination with chemotherapy for a more effective treatment of NSCLC.
Asunto(s)
Carcinoma de Pulmón de Células no Pequeñas/tratamiento farmacológico , Carcinoma de Pulmón de Células no Pequeñas/metabolismo , Células Madre Neoplásicas/citología , Células Madre Neoplásicas/efectos de los fármacos , Proteínas Quinasas/metabolismo , Animales , Western Blotting , Carcinoma de Pulmón de Células no Pequeñas/genética , Ciclo Celular/efectos de los fármacos , Diferenciación Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Quinasa 1 Reguladora del Ciclo Celular (Checkpoint 1) , Cisplatino/uso terapéutico , Daño del ADN/efectos de los fármacos , Desoxicitidina/análogos & derivados , Desoxicitidina/uso terapéutico , Inhibidores Enzimáticos/farmacología , Femenino , Técnica del Anticuerpo Fluorescente , Humanos , Ratones , Ratones Endogámicos NOD , Ratones SCID , Proteínas Quinasas/genética , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de Xenoinjerto , GemcitabinaRESUMEN
Stem cell factor (SCF), the ligand for the c-kit receptor, is essential for the production of red blood cells during development and stress erythropoiesis. SCF promotes erythroblast proliferation and survival, while delaying erythroid differentiation through mechanisms that are largely unknown. In cultures of primary human differentiating erythroblasts, we found that SCF induces an increase in the expression of Notch2, a member of the Notch family implicated in the control of cell growth and differentiation. Functional inhibition of either Notch or its ligand Jagged1 inhibited the effects of SCF on erythroid cell expansion. SCF also induced the expression of Hes-1 and GATA-2, which may contribute to transduce Notch2 signals in response to SCF. Transduction of primary erythroid precursors with a dominant-negative Notch2 mutant inhibited both basal and SCF-mediated erythroblast expansion, and counteracted the effects of SCF on erythroblast differentiation. These findings provide a clue to understand the effects of increased proliferation and delayed differentiation elicited by SCF on the erythroid compartment and indicate Notch2 as a new player in the regulation of red cell differentiation.
Asunto(s)
Proteínas de Unión al Calcio/metabolismo , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Proteínas de la Membrana/metabolismo , Receptor Notch2/metabolismo , Factor de Células Madre/metabolismo , Antígenos CD34/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Diferenciación Celular , Proliferación Celular , Células Cultivadas , Eritroblastos/citología , Eritroblastos/metabolismo , Factor de Transcripción GATA2/metabolismo , Proteínas de Homeodominio/metabolismo , Humanos , Proteína Jagged-1 , Receptor Notch2/genética , Proteínas Serrate-Jagged , Transducción de Señal , Factor de Transcripción HES-1Asunto(s)
Neoplasias del Colon/patología , Células Madre Neoplásicas/patología , Adenoma/patología , Células Madre Adultas/patología , Animales , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/patología , Neoplasias del Colon/diagnóstico , Neoplasias del Colon/terapia , Modelos Animales de Enfermedad , Humanos , RatonesAsunto(s)
Antineoplásicos/farmacología , Resistencia a Múltiples Medicamentos , Resistencia a Antineoplásicos , Células Madre Neoplásicas/efectos de los fármacos , Animales , Antineoplásicos/uso terapéutico , Apoptosis/efectos de los fármacos , Neoplasias Encefálicas/tratamiento farmacológico , Neoplasias Encefálicas/patología , Cisplatino/farmacología , Cisplatino/uso terapéutico , Doxorrubicina/farmacología , Doxorrubicina/uso terapéutico , Etopósido/farmacología , Etopósido/uso terapéutico , Glioblastoma/tratamiento farmacológico , Glioblastoma/patología , Humanos , Células Jurkat , Ratones , Ratones Desnudos , Células Madre Neoplásicas/patología , Factores de Tiempo , Células Tumorales Cultivadas , Ensayos Antitumor por Modelo de XenoinjertoRESUMEN
SCL/Tal-1 is a helix-loop-helix (HLH) transcription factor required for blood cell development, whose abnormal expression is responsible for induction of T-cell acute lymphoblastic leukemia. We show here that SCL/Tal-1 is a key target of caspases in developing erythroblasts. SCL/Tal-1 degradation occurred rapidly after caspase activation and preceded the cleavage of the major erythroid transcription factor GATA-1. Expression of a caspase-resistant SCL/Tal-1 in erythroid progenitors was able to prevent amplification of caspase activation, GATA-1 degradation and impaired erythropoiesis induced by growth factor deprivation or death receptor triggering. The potent proerythropoietic activity of uncleavable SCL/Tal-1 was clearly evident in the absence of erythropoietin, a condition that did not allow survival of normal erythroid cells or expansion of erythroblasts expressing caspase-resistant GATA-1. In the absence of erythropoietin, cells expressing caspase-resistant SCL/Tal-1 maintain high levels of Bcl-X(L), which inhibits amplification of the caspase cascade and mediates protection from apoptosis. Thus, SCL/TAL-1 is a survival factor for erythroid cells, whereas caspase-mediated cleavage of SCL/Tal-1 results in amplification of caspase activation, GATA-1 degradation and impaired erythropoiesis.
Asunto(s)
Caspasas/metabolismo , Proteínas de Unión al ADN/metabolismo , Eritropoyesis/fisiología , Proteínas Proto-Oncogénicas/metabolismo , Factores de Transcripción/metabolismo , Clorometilcetonas de Aminoácidos/farmacología , Anticuerpos/farmacología , Apoptosis/efectos de los fármacos , Linfocitos B/citología , Linfocitos B/efectos de los fármacos , Linfocitos B/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , Western Blotting , Caspasa 3 , Caspasa 7 , Caspasa 8 , División Celular/efectos de los fármacos , Clonación Molecular , Proteínas de Unión al ADN/genética , Regulación hacia Abajo , Precursores Enzimáticos/metabolismo , Eritroblastos/citología , Eritroblastos/efectos de los fármacos , Eritroblastos/metabolismo , Factores de Unión al ADN Específico de las Células Eritroides , Eritropoyetina/deficiencia , Eritropoyetina/farmacología , Factor de Transcripción GATA1 , Factor de Transcripción GATA2 , Regulación de la Expresión Génica , Proteínas Fluorescentes Verdes , Secuencias Hélice-Asa-Hélice/genética , Secuencias Hélice-Asa-Hélice/fisiología , Humanos , Proteínas Luminiscentes/genética , Proteínas Luminiscentes/metabolismo , Microscopía Fluorescente , Mutagénesis Sitio-Dirigida , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Proteína 1 de la Leucemia Linfocítica T Aguda , Factores de Transcripción/genética , Proteína bcl-X , Receptor fas/inmunología , Receptor fas/fisiologíaAsunto(s)
Apoptosis/genética , Proteínas de Unión al ADN/metabolismo , Monocitos/metabolismo , Fosfoproteínas/metabolismo , Receptor fas/genética , Apoptosis/efectos de los fármacos , Proteínas de Unión al ADN/genética , Expresión Génica , Humanos , Factor 1 Regulador del Interferón , Interferón gamma/farmacología , Monocitos/citología , Monocitos/efectos de los fármacos , Oligonucleótidos Antisentido/farmacología , Fosfoproteínas/genética , Factores de Tiempo , Células U937 , Receptor fas/metabolismoRESUMEN
Hashimoto's thyroiditis is a common chronic autoimmune disease characterized by the loss of thyroid follicular cells (thyrocytes) that are gradually replaced by lymphocytic infiltration and diffuse fibrosis. These morphological findings suggested that autoreactive T-cell clones were responsible for thyrocyte destruction and hypothyroidism through effector-target cytotoxic recognition. Later, autonomous interaction between thyrocyte Fas and FasL has been proposed as a major mechanism of thyrocyte depletion in Hashimoto's thyroiditis. Here, we analyze the possible role of Fas and FasL in the pathogenesis of Hashimoto's thyroiditis. We suggest that the Fas-FasL system dictates the outcome of the autoimmune response by acting on both immune and target cells.
Asunto(s)
Glicoproteínas de Membrana/fisiología , Tiroiditis Autoinmune/etiología , Receptor fas/fisiología , Apoptosis , Proteína Ligando Fas , HumanosRESUMEN
CD95 (Fas/Apo-1) is a broadly expressed death receptor involved in a variety of physiological and pathological apoptotic processes. Since its discovery, defects in CD95/CD95L system have been proposed as major pathogenic factors responsible for impaired immunological tolerance to self antigens and autoimmunity. Later, analysis of altered sensitivity to CD95-induced apoptosis in cells targeted by the immune response has revealed an unexpected role for CD95 and CD95L in organ-specific autoimmunity. CD95 has been shown to be expressed and functional in virtually all cell types that are target of the organ-specific autoimmune response. Here we review some of the major findings concerning the role of CD95 in autoimmunity, in dysfunctions due to increased or decreased CD95-induced apoptosis.
Asunto(s)
Autoinmunidad/fisiología , Glicoproteínas de Membrana/inmunología , Receptor fas/inmunología , Animales , Apoptosis/inmunología , Enfermedades Autoinmunes/inmunología , Enfermedades Autoinmunes/patología , Proteína Ligando Fas , HumanosAsunto(s)
Apoptosis/fisiología , Caspasas/metabolismo , Glicoproteínas de Membrana/metabolismo , Mitocondrias/fisiología , Factor de Necrosis Tumoral alfa/metabolismo , Animales , Proteínas Reguladoras de la Apoptosis , Humanos , Modelos Biológicos , Transducción de Señal/fisiología , Ligando Inductor de Apoptosis Relacionado con TNFRESUMEN
After autoimmune inflammation, interactions between CD95 and its ligand (CD95L) mediate thyrocyte destruction in Hashimoto's thyroiditis (HT). Conversely, thyroid autoimmune processes that lead to Graves' disease (GD) result in autoantibody-mediated thyrotropin receptor stimulation without thyrocyte depletion. We found that GD thyrocytes expressed CD95 and CD95L in a similar manner to HT thyrocytes, but did not undergo CD95-induced apoptosis either in vivo or in vitro. This pattern was due to the differential production of TH1 and TH2 cytokines. Interferon gamma promoted caspase up-regulation and CD95-induced apoptosis in HT thyrocytes, whereas interleukin 4 and interleukin 10 protected GD thyrocytes by potent up-regulation of cFLIP and Bcl-xL, which prevented CD95-induced apoptosis in sensitized thyrocytes. Thus, modulation of apoptosis-related proteins by TH1 and TH2 cytokines controls thyrocyte survival in thyroid autoimmunity.
Asunto(s)
Citocinas/metabolismo , Péptidos y Proteínas de Señalización Intracelular , Glicoproteínas de Membrana/metabolismo , Linfocitos T Colaboradores-Inductores/inmunología , Glándula Tiroides/inmunología , Glándula Tiroides/patología , Tiroiditis Autoinmune/inmunología , Tiroiditis Autoinmune/patología , Adulto , Animales , Apoptosis , Proteína Reguladora de Apoptosis Similar a CASP8 y FADD , Proteínas Portadoras/genética , Proteínas Portadoras/metabolismo , Supervivencia Celular , Proteína Ligando Fas , Enfermedad de Graves/inmunología , Enfermedad de Graves/metabolismo , Enfermedad de Graves/patología , Humanos , Técnicas In Vitro , Ratones , Ratones Transgénicos , Persona de Mediana Edad , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Células TH1/inmunología , Células Th2/inmunología , Glándula Tiroides/metabolismo , Tiroiditis Autoinmune/metabolismo , Proteína bcl-X , Receptor fas/metabolismoRESUMEN
Since molecular cloning of the C. elegans ced-3 gene revealed its homology with mammalian IL-1beta-converting enzyme,1 14 members of the caspase family have been identified, which have often been involved as mediators of one or more phases of the apoptotic process. 2,3 However, an over-simplified role of these proteases may be insufficient to explain the usually constitutive expression of such a large and complex family of enzymes, many of which display overlapping specificity. In addition to the well-established role of caspase-1 in the production of active IL-1beta and IL-18 in inflammation,4 an increasing number of reports has recently suggested that caspases may have a function outside of apoptosis. In this review, the situations in which cells survive despite the presence of activated caspases in their cytoplasm will be examined and discussed, with the intent to gather all recent advances in this new field that promises to be a focus for caspase research in the near future.
Asunto(s)
Apoptosis , Caspasas/metabolismo , Animales , Caspasa 1/inmunología , Caspasas/inmunología , Caspasas/fisiología , Diferenciación Celular , Activación Enzimática , Humanos , Interleucina-1/inmunología , Interleucina-18/inmunologíaRESUMEN
The production of red blood cells follows the sequential formation of proerythroblasts and basophilic, polychromatophilic and orthochromatic erythroblasts, and is promoted by the hormone erythropoietin (Epo) in response to tissue hypoxia. However, little is known about the negative regulation of this process. Death receptors are a family of surface molecules that trigger caspase activation and apoptosis in a variety of cell types. Here we show that immature erythroid cells express several death receptors whose ligands are produced by mature erythroblasts. Exposure of erythroid progenitors to mature erythroblasts or death-receptor ligands resulted in caspase-mediated degradation of the transcription factor GATA-1, which is associated with impaired erythroblast development. Expression of a caspase-resistant GATA-1 mutant, but not of the wild-type gene, completely restored erythroid expansion and differentiation following the triggering of death receptors, indicating that there is regulatory feedback between mature and immature erythroblasts through caspase-mediated cleavage of GATA-1. Similarly, erythropoiesis blockade following Epo deprivation was largely prevented by the expression of caspase-inhibitory proteins or caspase-resistant GATA-1 in erythroid progenitors. Caspase-mediated cleavage of GATA-1 may therefore represent an important negative control mechanism in erythropoiesis.
Asunto(s)
Apoptosis , Caspasas/metabolismo , Proteínas de Unión al ADN/fisiología , Eritropoyesis/fisiología , Factores de Transcripción/fisiología , Receptor fas/fisiología , Células Cultivadas , Clonación Molecular , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Activación Enzimática , Eritroblastos/fisiología , Factores de Unión al ADN Específico de las Células Eritroides , Eritropoyetina/fisiología , Proteína Ligando Fas , Factor de Transcripción GATA1 , Factor de Transcripción GATA2 , Humanos , Glicoproteínas de Membrana/fisiología , Mutagénesis , Mutación , Receptores de Superficie Celular/fisiología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Receptor fas/inmunologíaRESUMEN
The possible involvement of Fas and Fas ligand (FasL) in the regulation of erythropoiesis was evaluated. Immunohistochemistry of normal bone marrow specimens revealed that several immature erythroblasts undergo apoptosis in vivo. Analysis of bone marrow erythroblasts and purified progenitors undergoing unilineage erythroid differentiation showed that Fas is rapidly upregulated in early erythroblasts and expressed at high levels through terminal maturation. However, Fas crosslinking was effective only in less mature erythroblasts, particularly at basophilic level, where it induced apoptosis antagonized by high levels of erythropoietin (Epo). In contrast, FasL was selectively induced in late differentiating Fas-insensitive erythroblasts, mostly at the orthochromatic stage. FasL is functional in mature erythroblasts, as it was able to kill Fas-sensitive lymphoblast targets in a Fas-dependent manner. Importantly, FasL-bearing mature erythroblasts displayed a Fas-based cytotoxicity against immature erythroblasts, which was abrogated by high levels of Epo. These findings suggest the existence of a negative regulatory feedback between mature and immature erythroid cells, whereby the former cell population might exert a cytotoxic effect on the latter one in the erythroblastic island. Hypothetically, this negative feedback operates at low Epo levels to moderate the erythropoietic rate; however, it is gradually inhibited at increasing Epo concentrations coupled with enhanced erythrocyte production. Thus, the interaction of Fas and FasL may represent an apoptotic control mechanism for erythropoiesis, contributing to the regulation of red blood cell homeostasis.
Asunto(s)
Apoptosis/fisiología , Eritropoyesis/fisiología , Glicoproteínas de Membrana/fisiología , Receptor fas/fisiología , Adulto , Caspasas/fisiología , Diferenciación Celular/efectos de los fármacos , Células Cultivadas , Células Precursoras Eritroides/citología , Células Precursoras Eritroides/metabolismo , Proteína Ligando Fas , Retroalimentación , Homeostasis , Humanos , Masculino , Glicoproteínas de Membrana/biosíntesis , Receptor fas/biosíntesisRESUMEN
Therapeutic preparations of normal human IgG for i.v. use (i.v.Ig) exhibit a broad spectrum of immunoregulatory activities in vitro and in vivo. I.v.Ig has been shown to inhibit the proliferation of activated B and T lymphocytes and of several autonomously growing cell lines. In this study, we demonstrate that i.v.Ig induces apoptosis in leukemic cells of lymphocyte and monocyte lineage and in CD40-activated normal tonsillar B cells, involving, at least in part, Fas (CD95/APO-1) and activation of caspases. I.v.Ig-induced apoptosis was higher in Fas-sensitive HuT78 cells than in Fas-resistant HuT78.B1 mutant cells, and soluble Fas inhibited IVIg-induced apoptosis. I.v.Ig immunoprecipitated Fas from Fas-expressing transfectants and recognized purified Fas/glutathione-S-transferase fusion proteins upon immunoblotting. Affinity-purified anti-Fas Abs from i.v.Ig induced apoptosis of CEM T cells at a 120-fold lower concentration than unfractionated i.v.Ig. Inhibitors of cysteine proteases of the caspase family, caspase 1 (IL-1beta-converting enzyme) and caspase 3 (Yama/CPP32b), partially inhibited i.v.Ig-induced apoptosis of CEM cells. Furthermore, cleavage of poly(A)DP-ribose polymerase into an 85-kDa signature death fragment was observed in CEM cells following i.v.Ig treatment. Thus, normal IgG induces apoptosis in lymphocytes and monocytes. Our results provide evidence for a role of Fas, bring new insights into the mechanisms of action of i.v.Ig in autoimmune diseases, and suggest a role of normal Ig in controlling cell death and proliferation.