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1.
Oncogene ; 30(12): 1460-9, 2011 Mar 24.
Article in English | MEDLINE | ID: mdl-21102524

ABSTRACT

Expression of the intrinsic cellular caspase inhibitor XIAP is regulated primarily at the level of protein synthesis. The 5' untranslated region harbours an Internal Ribosome Entry Site (IRES) motif that supports cap-independent translation of XIAP mRNA during conditions of cellular stress. In this study, we show that the RNA-binding protein HuR, which is known to orchestrate an antiapoptotic cellular program, stimulates translation of XIAP mRNA through XIAP IRES. We further show that HuR binds to XIAP IRES in vitro and in vivo, and stimulates recruitment of the XIAP mRNA into polysomes. Importantly, protection from the apoptosis-inducing agent etoposide by overexpression of HuR requires the presence of XIAP, suggesting that HuR-mediated cytoprotection is partially executed through enhanced XIAP translation. Our data suggest that XIAP belongs to the HuR-regulated RNA operon of antiapoptotic genes, which, along with Bcl-2, Mcl-1 and ProTα, contributes to the regulation of cell survival.


Subject(s)
Antigens, Surface/metabolism , Protein Biosynthesis , RNA-Binding Proteins/metabolism , Ribosomes/metabolism , X-Linked Inhibitor of Apoptosis Protein/biosynthesis , Amino Acid Sequence , Cell Survival/genetics , Cytoprotection , ELAV Proteins , ELAV-Like Protein 1 , Gene Expression Regulation , HEK293 Cells , Humans , Molecular Sequence Data
2.
Cell Death Differ ; 17(7): 1189-98, 2010 Jul.
Article in English | MEDLINE | ID: mdl-20111042

ABSTRACT

It is commonly believed that neurons remain in G(0) phase of the cell cycle indefinitely. Cell-cycle re-entry, however, is known to contribute to neuronal apoptosis. Moreover, recent evidence demonstrates the expression of cell-cycle proteins in differentiated neurons under physiological conditions. The functional roles of such expression remain unclear. Since DNA repair is generally attenuated by differentiation in most cell types, the cell-cycle-associated events in postmitotic cells may reflect the need to re-enter the cell cycle to activate DNA repair. We show that cyclin-C-directed, pRb-dependent G(0) exit activates the non-homologous end joining pathway of DNA repair (NHEJ) in postmitotic neurons. Using RNA interference, we found that abrogation of cyclin-C-mediated exit from G(0) compromised DNA repair but did not initiate apoptosis. Forced G(1) entry combined with prevention of G(1) --> S progression triggered NHEJ activation even in the absence of DNA lesions, but did not induce apoptosis in contrast to unrestricted progression through G(1) --> S. We conclude that G(0) --> G(1) transition is functionally significant for NHEJ repair in postmitotic neurons. These findings reveal the importance of cell-cycle activation for controlling both DNA repair and apoptosis in postmitotic neurons, and underline the particular role of G(1) --> S progression in apoptotic signaling, providing new insights into the mechanisms of DNA damage response (DDR) in postmitotic neurons.


Subject(s)
Cell Cycle , Cyclin C/metabolism , DNA Repair , Neurons/metabolism , Apoptosis , Cyclin-Dependent Kinase Inhibitor p21/genetics , Cyclin-Dependent Kinase Inhibitor p21/metabolism , G1 Phase , Hydrogen Peroxide/pharmacology , Neurons/cytology , Phosphorylation , RNA Interference , RNA, Small Interfering/metabolism , Resting Phase, Cell Cycle , Retinoblastoma Protein/metabolism
3.
Oncogene ; 27(47): 6151-63, 2008 Oct 16.
Article in English | MEDLINE | ID: mdl-18641687

ABSTRACT

In a breast tumor xenograft model, the MCT-1 oncogene increases the in vivo tumorgenicity of MCF7 cells by promoting angiogenesis and inhibiting apoptosis. Increases in the tumor microvascular density are accompanied by a strong reduction in the levels of the angiogenesis inhibitor thrombospondin-1 (TSP1), but the mechanisms underlying this process are unknown. We show that TSP1 expression is controlled, at least in part, by post-transcriptional events. Using RNA interference to knock down the expression of the RNA-binding protein HuR in MCF7 cells as well as HuR overexpression, we demonstrate that HuR plays an important role in translation of the TSP1 mRNA. Furthermore, employing the RIP-Chip assay yielded 595 transcripts with significantly altered binding to HuR in the more tumorigenic breast cancer clones compared with the weakly tumorigenic clones. These mRNAs clustered in several pathways implicated in the transformed phenotype, such as the RAS pathway (involved in mitogenesis), the PI3K pathway (evasion of apoptosis) and pathways mediating angiogenesis and the cellular response to hypoxia. These findings demonstrate for the first time that global changes in HuR-bound mRNAs are implicated in the evolution to a more tumorigenic phenotype in an in vivo tumor model and underscore the role of global mRNA-protein interactions toward tumor progression.


Subject(s)
Antigens, Surface/physiology , Breast Neoplasms/metabolism , Gene Expression Regulation, Neoplastic , RNA-Binding Proteins/physiology , Thrombospondin 1/genetics , Breast Neoplasms/pathology , Cell Cycle Proteins/physiology , Cell Line, Tumor , ELAV Proteins , ELAV-Like Protein 1 , Female , Humans , Oncogene Proteins/physiology , Phenotype , Phosphatidylinositol 3-Kinases/physiology , Protein Biosynthesis , RNA, Messenger/analysis , RNA, Messenger/metabolism , RNA-Binding Proteins/antagonists & inhibitors , Signal Transduction , Transcription, Genetic
4.
Eur Respir J ; 26(5): 933-47, 2005 Nov.
Article in English | MEDLINE | ID: mdl-16264057

ABSTRACT

The aim of this review is to discuss recent advances in the understanding of the regulation of chemokine expression occurring during chronic inflammatory conditions, such as allergic diseases. The focus will be on current data, which suggest that post-transcriptional regulation plays a larger role in chemokine gene regulation than previously recognised. In particular, a growing body of data indicates that mechanisms controlling mRNA stability may be relevant in determining, or maintaining, the increased levels of chemokine gene expression in this context. Such regulatory pathways may be important targets of novel anti-inflammatory strategies.


Subject(s)
Chemokines/immunology , Gene Expression Regulation/immunology , Hypersensitivity/immunology , Inflammation/immunology , Models, Immunological , Protein Processing, Post-Translational/immunology , RNA Processing, Post-Transcriptional/immunology , Animals , Humans
5.
Acta Otorrinolaringol Esp ; 55(3): 131-8, 2004 Mar.
Article in Spanish | MEDLINE | ID: mdl-15253340

ABSTRACT

OBJECTIVE: To study in an animal model the local healing process after partial cricoid resection with thyrotracheal anastomosis. MATERIAL AND METHODS: Partial cricoid resection with thyrotracheal anastomosis was performed in 17 New Zealand rabbits. Experimental animals were gradually sacrificed and the laryngotracheal complex was removed to proceed to a histopathological study. RESULTS: An acute inflammatory response followed by a chronic inflammatory process was found in the surgical site. Normal tissue architecture was established after an eight week period. Anteroposterior and transverse diameters at all levels of the upper respiratory tract were not significantly altered at any time along the healing process. Experimental animals remained free from symptoms during the follow-up period. CONCLUSIONS: These results support that partial cricoid resection with thyrotracheal anastomosis is a safe procedure for the treatment of severe laryngotracheal stenosis.


Subject(s)
Cricoid Cartilage/pathology , Cricoid Cartilage/surgery , Thyroid Gland/pathology , Thyroid Gland/surgery , Trachea/pathology , Trachea/surgery , Anastomosis, Surgical/methods , Animals , Rabbits
6.
Acta otorrinolaringol. esp ; 55(3): 131-138, mar. 2004. ilus, tab
Article in Es | IBECS | ID: ibc-30542

ABSTRACT

Objetivo: Estudiar en un modelo animal el proceso de reparación tisular que tiene lugar tras la realización de una resección cricoidea parcial con anastomosis tirotraqueal. Material y métodos: Realizamos un estudio experimental en 17 conejos New Zealand a los que se realizó el citado procedimiento. Los animales fueron sacrificados escalonadamente y el complejo laringotraqueal fue extraído y sometido a un estudio histopatológico. Resultados: La zona operada mostró una reacción inflamatoria primero aguda y luego crónica que se fue resolviendo a lo largo del tiempo, restableciéndose una arquitectura tisular normal alrededor de las ocho semanas de la intervención; los diámetros anteroposterior y transverso de la vía aérea superior a sus distintos niveles no se vieron alterados de manera significativa en ningún momento. Los animales permanecieron asintomáticos durante todo el período postoperatorio. Conclusiones: La resección cricoidea parcial con anastomosis tirotraqueal es un procedimiento seguro para el tratamiento de las estenosis laringotraqueales severas (AU)


OBJECTIVE: To study in an animal model the local healing process after partial cricoid resection with thyrotracheal anastomosis. MATERIAL AND METHODS: Partial cricoid resection with thyrotracheal anastomosis was performed in 17 New Zealand rabbits. Experimental animals were gradually sacrificed and the laryngotracheal complex was removed to proceed to a histopathological study. RESULTS: An acute inflammatory response followed by a chronic inflammatory process was found in the surgical site. Normal tissue architecture was established after an eight week period. Anteroposterior and transverse diameters at all levels of the upper respiratory tract were not significantly altered at any time along the healing process. Experimental animals remained free from symptoms during the follow-up period. CONCLUSIONS: These results support that partial cricoid resection with thyrotracheal anastomosis is a safe procedure for the treatment of severe laryngotracheal stenosis (AU)


Subject(s)
Animals , Rabbits , Trachea/pathology , Thyroid Gland/pathology , Cricoid Cartilage/pathology , Cricoid Cartilage/surgery , Thyroid Gland/surgery , Trachea/surgery , Anastomosis, Surgical/methods
7.
Arch Bronconeumol ; 38(1): 51-4, 2002 Jan.
Article in Spanish | MEDLINE | ID: mdl-11809138

ABSTRACT

Postpneumonectomy syndrome is a rare complication of pneumonectomy that develops as a result of excessive displacement of mediastinal structures into the empty cavity. We report the case of a 72-year-old man who developed dysphagia and progressive weakness, along with signs of hypotension due to low cardiac output, following removal of the left lung for lung cancer. Intubation and transfer to the intensive care unit was necessary. When such causes as pulmonary embolism, pneumonia and COPD exacerbation had been ruled out, postpneumonectomy syndrome was diagnosed. Two tissue expansion prostheses (100 mL and 400 mL) were implanted surgically to keep the mediastinum in position and reverse symptoms immediately. We conclude that postpneumonectomy syndrome after left pneumonectomy is a rare complication that may be more frequent than the literature suggests, given that signs may be masked by a diagnosis of cardiogenic shock that leads to death. Surgical repair is simple, reversing symptoms immediately.


Subject(s)
Pneumonectomy/adverse effects , Postoperative Complications/surgery , Vascular Diseases/surgery , Aged , Humans , Male , Postoperative Complications/etiology , Syndrome , Vascular Diseases/etiology
8.
Arch. bronconeumol. (Ed. impr.) ; 38(1): 51-54, ene. 2002.
Article in Es | IBECS | ID: ibc-6623

ABSTRACT

El síndrome posneumonectomía es una complicación inusual de la neumonectomía, consecuencia del desplazamiento excesivo de las estructuras mediastínicas hacia el espacio pleural vacío. Presentamos el caso de un varón de 72 años que, tras ser sometido a una neumonectomía izquierda por una neoplasia de pulmón, desarrolló un cuadro de disfagia y fatigabilidad progresiva, junto con un signo de hipotensión arterial por bajo gasto cardíaco, lo que obligó a una intubación e ingreso en la UCI. Descartadas alteraciones como embolismo pulmonar, neumonía, reagudización de una enfermedad pulmonar obstructiva crónica, etc., y tras comprobar el excesivo desplazamiento del mediastino, se diagnosticó de síndrome posneumonectomía. Se intervino quirúrgicamente, introduciéndose dos prótesis de expansión tisular de 1.000 ml y 400 ml, para mantener la recolocación del mediastino, corrigiéndose el cuadro de forma inmediata. Concluimos que el síndrome posneumonectomía tras la neumonectomía izquierda es una complicación inusual, pero que puede ser más alta de lo que se ha publicado, ya que el cuadro puede quedar enmascarado como un shock cardiogénico y conducir a la muerte del paciente, sin llegar a realizarse un diagnóstico etiológico. Además su corrección quirúrgica es sencilla y determina la desaparición inmediata de los síntomas (AU)


Subject(s)
Aged , Male , Humans , Vascular Diseases , Syndrome , Postoperative Complications , Pneumonectomy
9.
Mol Cell Biol ; 21(23): 8213-24, 2001 Dec.
Article in English | MEDLINE | ID: mdl-11689710

ABSTRACT

Mitogen-activated protein (MAP) kinase phosphatase 1 (MKP-1) has been shown to play a critical role in mediating the feedback control of MAP kinase cascades in a variety of cellular processes, including proliferation and stress responsiveness. Although MKP-1 expression is induced by a broad array of extracellular stimuli, the mechanisms mediating its induction remain poorly understood. Here we show that MKP-1 mRNA was potently induced by arsenite and ultraviolet light and modestly increased by heat shock and hydrogen peroxide. Interestingly, arsenite also dramatically induces phosphorylation-acetylation of histone H3 at a global level which precedes the induction of MKP-1 mRNA. The transcriptional induction of MKP-1, histone H3 modification, and elevation in MKP-1 mRNA in response to arsenite are all partially prevented by the p38 MAP kinase inhibitor SB203580, suggesting that the p38 pathway is involved in these processes. Finally, analysis of the DNA brought down by chromatin immunoprecipitation (ChIP) reveals that arsenite induces phosphorylation-acetylation of histone H3 associated with the MKP-1 gene and enhances binding of RNA polymerase II to MKP-1 chromatin. ChIP assays following exposure to other stress agents reveal various degrees of histone H3 modification at the MKP-1 chromatin. The differential contribution of p38 and ERK MAP kinases in mediating MKP-1 induction by different stress agents further illustrates the complexity and versatility of stress-induced MKP-1 expression. Our results strongly suggest that chromatin remodeling after stress contributes to the transcriptional induction of MKP-1.


Subject(s)
Cell Cycle Proteins , Enzyme Induction/physiology , Fibroblasts/metabolism , Histones/metabolism , Immediate-Early Proteins/metabolism , Phosphoprotein Phosphatases , Protein Tyrosine Phosphatases/metabolism , Ribosomal Protein S6 Kinases, 90-kDa , Stress, Physiological/metabolism , Acetylation/drug effects , Acetylation/radiation effects , Animals , Arsenites/pharmacology , Calcium-Calmodulin-Dependent Protein Kinases/metabolism , Cell Line , Chromatin/metabolism , Dual Specificity Phosphatase 1 , Enzyme Induction/drug effects , Enzyme Induction/radiation effects , Enzyme Inhibitors/pharmacology , Fibroblasts/cytology , Heat-Shock Response/physiology , Histone Deacetylase Inhibitors , Histones/chemistry , Humans , Hydrogen Peroxide/pharmacology , Immediate-Early Proteins/genetics , Mice , Mice, Inbred C3H , Mitogen-Activated Protein Kinases/antagonists & inhibitors , Mitogen-Activated Protein Kinases/metabolism , Oxidants/pharmacology , Phosphorylation/drug effects , Phosphorylation/radiation effects , Protein Phosphatase 1 , Protein Tyrosine Phosphatases/genetics , RNA Polymerase II/metabolism , RNA, Messenger/metabolism , Ultraviolet Rays , p38 Mitogen-Activated Protein Kinases
10.
Med. cután. ibero-lat.-am ; 29(5): 285-288, sept. 2001. ilus
Article in Es | IBECS | ID: ibc-14868

ABSTRACT

El tumor de Abrikossoff o tumor de células granulares es una rara entidad y su presentación cutánea multiple es infrecuente.Se describe un caso de localización en cuello, espalda y antebrazo. Se comenta su histología, inmunohistoquímica y las hipótesis histopatogénicas más aceptadas (AU)


Subject(s)
Adult , Female , Humans , Granular Cell Tumor/diagnosis , Skin Neoplasms/diagnosis , Granular Cell Tumor/surgery , Granular Cell Tumor/pathology , Biopsy , Neck/pathology , Back/pathology , Forearm/pathology , Immunohistochemistry , Skin Neoplasms/surgery , Skin Neoplasms/pathology
11.
Mol Cell Biol ; 21(17): 5889-98, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11486028

ABSTRACT

Cellular aging is accompanied by alterations in gene expression patterns. Here, using two models of replicative senescence, we describe the influence of the RNA-binding protein HuR in regulating the expression of several genes whose expression decreases during senescence. We demonstrate that HuR levels, HuR binding to target mRNAs encoding proliferative genes, and the half-lives of such mRNAs are lower in senescent cells. Importantly, overexpression of HuR in senescent cells restored a "younger" phenotype, while a reduction in HuR expression accentuated the senescent phenotype. Our studies highlight a critical role for HuR during the process of replicative senescence.


Subject(s)
Aging/genetics , Antigens, Surface , Gene Expression Regulation , RNA-Binding Proteins/metabolism , Aged , Aging/metabolism , Cell Line , Cellular Senescence , ELAV Proteins , ELAV-Like Protein 1 , Fibroblasts/cytology , Fibroblasts/metabolism , Humans , Phenotype , RNA, Messenger , Skin/cytology
12.
J Biol Chem ; 276(31): 29440-9, 2001 Aug 03.
Article in English | MEDLINE | ID: mdl-11387337

ABSTRACT

MKP-2 is a member of the mitogen-activated protein (MAP) kinase phosphatase family which has been suggested to play an important role in the feedback control of MAP kinase-mediated gene expression. Although MKP-2 preferentially inactivates extracellular signal-regulated kinase (ERK) and c-Jun NH(2)-terminal kinase (JNK) MAP kinase subfamilies, the mechanisms underlying its own regulation remain unclear. In this report, we have examined the MKP-2 interaction with and catalytic activation by distinct MAP kinase subfamilies. We found that the catalytic activity of MKP-2 was enhanced dramatically by ERK and JNK but was affected only minimally by p38. By contrast, p38 and ERK bound MKP-2 with comparably strong affinities, whereas JNK and MKP-2 interacted very weakly. Through site-directed mutagenesis, we defined the ERK/p38-binding site as a cluster of arginine residues in the NH(2)-terminal domain of MKP-2. Mutation of the basic motif abrogated its interaction with both ERK and p38 and severely compromised the catalytic activation of MKP-2 by these kinases. Unexpectedly, such mutations had little effect on JNK-triggered catalytic activation. Both in vitro and in vivo, wild type MKP-2 effectively inactivated ERK2 whereas MKP-2 mutants incapable of binding to ERK/p38 did not. Finally, in addition to its role as a docking site for ERK and p38, the MKP-2 basic motif plays a role in regulating its nuclear localization. Our studies provided a mechanistic explanation for the substrate preference of MKP-2 and suggest that catalytic activation of MKP-2 upon binding to its substrates is crucial for its function.


Subject(s)
MAP Kinase Signaling System/physiology , Mitogen-Activated Protein Kinases/metabolism , Protein Tyrosine Phosphatases/metabolism , Amino Acid Substitution , Binding Sites , Cell Line , Dual-Specificity Phosphatases , Enzyme Activation , Genetic Vectors , Glutathione Transferase/metabolism , HeLa Cells , Humans , Kinetics , Mitogen-Activated Protein Kinase 1/metabolism , Mitogen-Activated Protein Kinase 3 , Mitogen-Activated Protein Kinase 8 , Mitogen-Activated Protein Kinase Phosphatases , Mitogen-Activated Protein Kinases/chemistry , Mutagenesis, Site-Directed , Protein Phosphatase 2 , Protein Tyrosine Phosphatases/chemistry , Recombinant Fusion Proteins/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Transfection , p38 Mitogen-Activated Protein Kinases
13.
Cancer Res ; 61(4): 1493-9, 2001 Feb 15.
Article in English | MEDLINE | ID: mdl-11245456

ABSTRACT

Fatty acid synthetic metabolism is abnormally elevated in tumor cells, and pharmacological inhibitors of the anabolic enzyme fatty acid synthase (FAS), including the natural product cerulenin and the novel synthetic compound c75, are selective inhibitors of tumor cell growth. We have recently reported that these two FAS inhibitors both produce rapid, potent inhibition of DNA replication and S-phase progression in human cancer cells, as well as apoptotic death. Here we report an additional characterization of the cellular response to FAS inhibition. RKO colon carcinoma cells were selected for study because they undergo little apoptosis within the first 24 h after FAS inhibition. Instead, RKO cells exhibited a biphasic stress response with a transient accumulation in S and G2 at 4 and 8 h that corresponds to a marked reduction in cyclin A- and B1-associated kinase activities, and then by accumulation of p53 and p21 proteins at 16 and 24 h and growth arrest in G1 and G2. The response of RKO cells to FAS inhibition resembled a genotoxic stress response, but DNA damage did not appear to be an important downstream effect of FAS inhibition, because none was detected using the single cell gel electrophoresis assay (comet assay) to assess DNA damage. p53 function is probably important in protecting RKO cells from FAS inhibition because, similar to many other tumor lines, RKO cells expressing a dominant negative mutant p53 gene underwent extensive apoptosis within 24 h after FAS inhibition. Sensitization of cells to FAS inhibitors by the loss of p53 raises the possibility that these agents may be clinically useful against malignancies carrying p53 mutations. Whereas induction of apoptosis appeared related to accumulation of the substrate, malonyl-CoA, after FAS inhibition, the cytostatic effects were independent of malonyl-CoA accumulation and may have resulted from product depletion.


Subject(s)
Fatty Acid Synthases/antagonists & inhibitors , Tumor Suppressor Protein p53/physiology , Colonic Neoplasms/enzymology , Colonic Neoplasms/pathology , Cyclin-Dependent Kinase Inhibitor p21 , Cyclin-Dependent Kinases/antagonists & inhibitors , Cyclin-Dependent Kinases/metabolism , Cyclins/biosynthesis , Enzyme Activation , G2 Phase/drug effects , Humans , Malonyl Coenzyme A/metabolism , S Phase/drug effects , Tumor Cells, Cultured , Tumor Suppressor Protein p53/biosynthesis
14.
Free Radic Biol Med ; 29(11): 1166-76, 2000 Dec.
Article in English | MEDLINE | ID: mdl-11121725

ABSTRACT

While the Ku complex, comprised of Ku70 and Ku80, is primarily involved in the repair of DNA double-strand breaks, it is also believed to participate in additional cellular processes. Here, treatment of embryo fibroblasts (MEFs) derived from either wild-type or Ku80-null (Ku80(-/-)) mice with various stress agents revealed that hydrogen peroxide (H(2)O(2)) was markedly more cytotoxic for Ku80(-/-) MEFs and led to their long-term accumulation in the G2 phase. This differential response was not due to differences in DNA repair, since H(2)O(2)-triggered DNA damage was repaired with comparable efficiency in both Wt and Ku80(-/-) MEFs, but was associated with differences in the expression of important cell cycle regulatory genes. Our results support the notion that Ku80-mediated cytoprotection and G2-progression are not only dependent on the cell's DNA repair but also may reflect Ku80's influence on additional cellular processes such as gene expression.


Subject(s)
Antigens, Nuclear , DNA Helicases , DNA Repair , DNA-Binding Proteins/deficiency , G2 Phase/drug effects , Hydrogen Peroxide/pharmacology , Nuclear Proteins/deficiency , Animals , Cell Line , Cell Survival/drug effects , Colony-Forming Units Assay , Cyclins/genetics , DNA Damage , DNA-Binding Proteins/physiology , Embryo, Mammalian , Fibroblasts/cytology , Fibroblasts/drug effects , Fibroblasts/metabolism , Flow Cytometry , Free Radicals , Gamma Rays , Immunosorbent Techniques , Ku Autoantigen , Mice , Mice, Knockout , Nuclear Proteins/physiology
15.
Mol Cell Biol ; 20(21): 7903-13, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11027261

ABSTRACT

Prostaglandin A(2) (PGA(2)), an experimental chemotherapeutic agent, causes growth arrest associated with decreased cyclin D1 expression in several cancer cell lines. Here, using human non-small-cell lung carcinoma H1299 cells, we investigated the mechanisms whereby PGA(2) down-regulates cyclin D1 expression. Transcription rates of the cyclin D1 gene, studied using a cyclin D1 promoter-luciferase construct and nuclear run-on assays, were not affected by PGA(2) treatment. Instead, the cyclin D1 mRNA was rendered unstable after exposure to PGA(2). Since the stability of labile mRNA is modulated through binding of proteins to specific mRNA sequences, we sought to identify protein(s) recognizing the cyclin D1 mRNA. In electrophoretic mobility-shift assays using radiolabeled RNA probes derived from different regions of cyclin D1 mRNA, we observed that (i) lysates prepared from PGA(2)-treated cells exhibited enhanced protein-cyclin D1 RNA complex formation; (ii) the kinetics of complex formation correlated closely with that of cyclin D1 mRNA loss; and (iii) binding occurred within a 390-base cyclin D1 3' untranslated region (UTR) (K12). This binding activity could be cross-linked, revealing proteins ranging from 30 to 47 kDa. The RNA-binding protein AUF1, previously associated with the degradation of target mRNAs, bound cyclin D1 mRNA, because anti-AUF1 antibodies were capable of supershifting or immunoprecipitating cyclin D1 mRNA-protein complexes. Finally, insertion of K12 in the 3'UTR of reporter genes markedly reduced the expression and half-life of the resulting chimeric mRNAs in transfected, PGA(2)-treated cells. Our data demonstrate that PGA(2) down-regulates cyclin D1 expression by decreasing cyclin D1 mRNA stability and implicates a 390-base element in the 3'UTR in this regulation.


Subject(s)
Cyclin D1/genetics , Cyclin D1/metabolism , Down-Regulation , Heterogeneous-Nuclear Ribonucleoprotein D , Prostaglandins A/metabolism , RNA, Messenger/metabolism , 3' Untranslated Regions , Blotting, Northern , Blotting, Western , Cell Division/drug effects , Cell Nucleus/metabolism , Cross-Linking Reagents/pharmacology , Cytoplasm/metabolism , Dose-Response Relationship, Drug , Genes, Reporter , Heterogeneous Nuclear Ribonucleoprotein D0 , Humans , Kinetics , Models, Genetic , Precipitin Tests , Promoter Regions, Genetic , Prostaglandins A/genetics , Protein Binding , RNA/metabolism , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Subcellular Fractions , Time Factors , Transcription, Genetic , Transcriptional Activation , Transfection , Tumor Cells, Cultured
16.
EMBO J ; 19(10): 2340-50, 2000 May 15.
Article in English | MEDLINE | ID: mdl-10811625

ABSTRACT

Colorectal carcinoma RKO cells expressing reduced levels of the RNA-binding protein HuR (ASHuR) displayed markedly reduced growth. In synchronous RKO populations, HuR was almost exclusively nuclear during early G(1), increasing in the cytoplasm during late G(1), S and G(2). The expression and half-life of mRNAs encoding cyclins A and B1 similarly increased during S and G(2), then declined, indicating that mRNA stabilization contributed to their cell cycle-regulated expression. In gel-shift assays using radiolabeled cyclin RNA transcripts and RKO protein extracts, only those transcripts corresponding to the 3'-untranslated regions of cyclins A and B1 formed RNA-protein complexes in a cell cycle-dependent fashion. HuR directly bound mRNAs encoding cyclins A and B1, as anti-HuR antibodies supershifted such RNA-protein complexes. Importantly, the expression and half-life of mRNAs encoding cyclins A and B1 were reduced in ASHuR RKO cells. Our results indicate that HuR may play a critical role in cell proliferation, at least in part by mediating cell cycle-dependent stabilization of mRNAs encoding cyclins A and B1.


Subject(s)
Antigens, Surface , Cell Cycle/genetics , Cyclin A/genetics , Cyclin B/genetics , RNA, Messenger/genetics , RNA-Binding Proteins/genetics , Cell Division/genetics , Cyclin B1 , ELAV Proteins , ELAV-Like Protein 1 , Gene Expression Regulation, Neoplastic , Humans , Transcription, Genetic , Tumor Cells, Cultured
17.
J Biol Chem ; 275(32): 24767-75, 2000 Aug 11.
Article in English | MEDLINE | ID: mdl-10825181

ABSTRACT

The c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK) pathway is activated by numerous cellular stresses. Although it has been implicated in mediating apoptosis and growth factor signaling, its role in regulating cell growth is not yet clear. Here, the influence of JNK on basal (unstimulated) growth of human tumor glioblastoma T98G cells was investigated using highly specific JNK antisense oligonucleotides to inhibit JNK expression. Transient depletion of either JNK1 or JNK2 suppressed cell growth associated with an inhibition of DNA synthesis and cell cycle arrest in S phase. The growth-inhibitory potency of JNK2 antisense ((JNK)2 IC(50) = 0.14 micrometer) was greater than that of JNK1 antisense ((JNK)1 IC(50) = 0.37 micrometer), suggesting that JNK2 plays a dominant role in regulating growth of T98G cells. Indeed, JNK2 antisense-treated populations exhibited greater inhibition of DNA synthesis and accumulation of S-phase cells than did the JNK1 antisense-treated cultures, with a significant proportion of these cells detaching from the tissue culture plate. JNK2 (but not JNK1) antisense-treated cultures exhibited marked elevation in the expression of the cyclin-dependent kinase inhibitor p21(cip1/waf1) accompanied by inhibition of Cdk2/Cdc2 kinase activities. Taken together, these results indicate that JNK is required for growth of T98G cells in nonstress conditions and that p21(cip1/waf1) may contribute to the sustained growth arrest of JNK2-depleted T98G cultures.


Subject(s)
Cell Cycle/drug effects , Cell Division/physiology , Mitogen-Activated Protein Kinases/genetics , Oligodeoxyribonucleotides, Antisense/pharmacology , Transcription, Genetic/drug effects , Cell Division/drug effects , DNA, Neoplasm/biosynthesis , Gene Expression Regulation, Neoplastic/drug effects , Glioblastoma , Humans , JNK Mitogen-Activated Protein Kinases , Kinetics , Mitogen-Activated Protein Kinase 8 , Mitogen-Activated Protein Kinase 9 , Mitogen-Activated Protein Kinases/metabolism , S Phase , Thionucleotides , Tumor Cells, Cultured
18.
Mol Cell Biol ; 20(5): 1713-22, 2000 Mar.
Article in English | MEDLINE | ID: mdl-10669748

ABSTRACT

c-Jun N-terminal kinase (JNK) plays a critical role in coordinating the cellular response to stress and has been implicated in regulating cell growth and transformation. To investigate the growth-regulatory functions of JNK1 and JNK2, we used specific antisense oligonucleotides (AS) to inhibit their expression. A survey of several human tumor cell lines revealed that JNKAS treatment markedly inhibited the growth of cells with mutant p53 status but not that of cells with normal p53 function. To further examine the influence of p53 on cell sensitivity to JNKAS treatment, we compared the responsiveness of RKO, MCF-7, and HCT116 cells with normal p53 function to that of RKO E6, MCF-7 E6, and HCT116 p53(-/-), which were rendered p53 deficient by different methods. Inhibition of JNK2 (and to a lesser extent JNK1) expression dramatically reduced the growth of p53-deficient cells but not that of their normal counterparts. JNK2AS-induced growth inhibition was correlated with significant apoptosis. JNK2AS treatment induced the expression of the cyclin-dependent kinase inhibitor p21(Cip1/Waf1) in parental MCF-7, RKO, and HCT116 cells but not in the p53-deficient derivatives. That p21(Cip1/Waf1) expression contributes to the survival of JNK2AS-treated cells was supported by additional experiments demonstrating that p21(Cip1/Waf1) deficiency in HCT116 cells also results in heightened sensitivity to JNKAS treatment. Our results indicate that perturbation of JNK2 expression adversely affects the growth of otherwise nonstressed cells. p53 and its downstream effector p21(Cip1/Waf1) are important in counteracting these detrimental effects and promoting cell survival.


Subject(s)
Apoptosis , Mitogen-Activated Protein Kinases , Protein Kinases/genetics , Tumor Suppressor Protein p53/genetics , Apoptosis/genetics , Cell Division/genetics , Cell Survival/genetics , Female , Gene Expression Regulation, Enzymologic , Gene Expression Regulation, Neoplastic , Humans , Mitogen-Activated Protein Kinase 9 , Protein Kinases/biosynthesis , Signal Transduction/genetics , Tumor Cells, Cultured , Tumor Suppressor Protein p53/metabolism
19.
Mol Cell Biol ; 20(3): 760-9, 2000 Feb.
Article in English | MEDLINE | ID: mdl-10629032

ABSTRACT

Expression of the cyclin-dependent kinase inhibitor p21 is highly induced by many stresses, including exposure to short-wavelength UV light (UVC), which increases p21 mRNA stability. Investigation into the mechanisms underlying this stabilization process revealed that proteins present in cytoplasmic lysates of human RKO colorectal carcinoma cells formed complexes with p21 mRNA that were inducible by treatment with UVC and other stress agents. The ubiquitous Elav-type RNA-binding protein HuR was identified within the p21 mRNA-protein complexes, as antibodies recognizing HuR supershifted these complexes and revealed HuR-immunoreactive proteins complexing with p21 mRNA on Western blots. Lowering of endogenous HuR levels through expression of antisense HuR decreased p21 RNA-protein complexes, greatly reduced the UVC inducibility and half-life of p21 mRNA, and prevented UVC-mediated induction of luciferase activity in p21 3' untranslated region-containing reporter constructs. Our findings indicate that HuR plays a major role in regulating stress-induced p21 expression by enhancing p21 mRNA stability and that these effects are coupled to HuR's elevated presence in the cytoplasm.


Subject(s)
Antigens, Surface , Cyclins/genetics , Cyclins/metabolism , Gene Expression Regulation, Neoplastic/radiation effects , RNA-Binding Proteins/metabolism , Ultraviolet Rays , Blotting, Western , Cell Nucleus/metabolism , Colorectal Neoplasms , Cyclin-Dependent Kinase Inhibitor p21 , Cyclins/isolation & purification , Cytoplasm/metabolism , Dactinomycin/pharmacology , ELAV Proteins , ELAV-Like Protein 1 , Enzyme Inhibitors/metabolism , Gene Expression Regulation, Neoplastic/drug effects , Gene Expression Regulation, Neoplastic/physiology , Green Fluorescent Proteins , Humans , Hydrogen Peroxide/pharmacology , Luminescent Proteins/genetics , Methyl Methanesulfonate/pharmacology , Polymerase Chain Reaction , RNA, Messenger/genetics , RNA, Messenger/radiation effects , RNA-Binding Proteins/genetics , RNA-Binding Proteins/isolation & purification , Signal Transduction , Transcription, Genetic/drug effects , Transcription, Genetic/radiation effects , Transfection , Tumor Cells, Cultured
20.
Arch Bronconeumol ; 35(9): 417-21, 1999 Oct.
Article in Spanish | MEDLINE | ID: mdl-10596337

ABSTRACT

This paper analyzes the influence of perioperative transfusion on survival after lung cancer surgery. Between January 1991 and December 1995, we enrolled 405 patients, 196 of whom received transfusions and 209 of whom did not. Follow-up extended to December 1997. Excluded were patients undergoing exploratory thoracotomy (n = 92), those who died during the postoperative period (n = 19) and those lost to follow-up (n = 13). The final number of patients in the study was 281 (136 who received transfusions and 145 who did not). We analyzed age, sex, general clinical status measured on the Eastern Cooperative Oncology Group (ECOG) scale, histological type and TNM staging. Single and multiple variable analyses were performed. At the end of the study 158 patients were alive and 123 had died. Transfusions were used more often in pneumonectomies (p < 0.001) and in patients with an ECOG score of 2 (p < 0.01). Survival at 36 and 60 months, calculated using the Kaplan-Meier method was 52% and 30%, respectively, for those who had received transfusions, and 53% and 49%, respectively, for those who had not. The differences were not statistically significant (p > 0.1). Multivariant analysis failed to demonstrate an influence of transfusion on survival (relative risk of 1.08; 95% confidence interval 0.72-1.61; p > 0.1). We conclude that there is no negative prognostic effect of perioperative transfusion.


Subject(s)
Adenocarcinoma/mortality , Blood Transfusion , Carcinoma, Large Cell/mortality , Carcinoma, Squamous Cell/mortality , Intraoperative Care , Lung Neoplasms/mortality , Pneumonectomy/mortality , Adenocarcinoma/pathology , Adenocarcinoma/surgery , Blood Transfusion/statistics & numerical data , Carcinoma, Large Cell/pathology , Carcinoma, Large Cell/surgery , Carcinoma, Squamous Cell/pathology , Carcinoma, Squamous Cell/surgery , Female , Follow-Up Studies , Humans , Intraoperative Care/statistics & numerical data , Lung Neoplasms/pathology , Lung Neoplasms/surgery , Male , Middle Aged , Multivariate Analysis , Neoplasm Staging , Pneumonectomy/statistics & numerical data , Retrospective Studies , Spain/epidemiology
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