Publications by authors named "María Dolores Pastor"

17 Publications

  • Page 1 of 1

Identification of Predictive Biomarkers of Response to HSP90 Inhibitors in Lung Adenocarcinoma.

Int J Mol Sci 2021 Mar 3;22(5). Epub 2021 Mar 3.

CIBERONC, Respiratory Tract Tumors Program, 28029 Madrid, Spain.

Heat shock protein 90 (HSP90) plays an essential role in lung adenocarcinoma, acting as a key chaperone involved in the correct functioning of numerous highly relevant protein drivers of this disease. To this end, HSP90 inhibitors have emerged as promising therapeutic strategies, even though responses to them have been limited to date. Given the need to maximize treatment efficacy, the objective of this study was to use isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic techniques to identify proteins in human lung adenocarcinoma cell lines whose basal abundances were correlated with response to HSP90 inhibitors (geldanamycin and radicicol derivatives). From the protein profiles identified according to response, the relationship between lactate dehydrogenase B (LDHB) and DNA topoisomerase 1 (TOP1) with respect to sensitivity and resistance, respectively, to geldanamycin derivatives is noteworthy. Likewise, rhotekin (RTKN) and decaprenyl diphosphate synthase subunit 2 (PDSS2) were correlated with sensitivity and resistance to radicicol derivatives. We also identified a relationship between resistance to HSP90 inhibition and the p53 pathway by glucose deprivation. In contrast, arginine biosynthesis was correlated with sensitivity to HSP90 inhibitors. Further study of these outcomes could enable the development of strategies to improve the clinical efficacy of HSP90 inhibition in patients with lung adenocarcinoma.
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http://dx.doi.org/10.3390/ijms22052538DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7962034PMC
March 2021

Impact of Heat Shock Protein 90 Inhibition on the Proteomic Profile of Lung Adenocarcinoma as Measured by Two-Dimensional Electrophoresis Coupled with Mass Spectrometry.

Cells 2019 07 31;8(8). Epub 2019 Jul 31.

H12O-CNIO Lung Cancer Clinical Research Unit, Instituto de Investigación Hospital 12 de Octubre & Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain.

Heat shock protein 90 (HSP90) is an important chaperone in lung adenocarcinoma, with relevant protein drivers such as EGFR (epidermal growth factor receptor) and EML4-ALK (echinoderm microtubule-associated protein-like protein4 fused to anaplastic lymphoma kinase) depending on it for their correct function, therefore HSP90 inhibitors show promise as potential treatments for lung adenocarcinoma. To study responses to its inhibition, HSP90 was pharmacologically interrupted by geldanamycin and resorcinol derivatives or with combined inhibition of HSP90 plus HSP70 in lung adenocarcinoma cell lines. Two-dimensional electrophoresis was performed to identify proteomic profiles associated with inhibition which will help to understand the biological basis for the responses. HSP90 inhibition resulted in altered protein profiles that differed according the treatment condition studied. Results revealed 254 differentially expressed proteins after treatments, among which, eukaryotic translation initiation factor3 subunit I (eIF3i) and citrate synthase demonstrated their potential role as response biomarkers. The differentially expressed proteins also enabled signalling pathways involved in responses to be identified; these included apoptosis, serine-glycine biosynthesis and tricarboxylic acid cycle. The proteomic profiles identified here contribute to an improved understanding of HSP90 inhibition and open possibilities for the detection of potential response biomarkers which will be essential to maximize treatment efficacy in lung adenocarcinoma.
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http://dx.doi.org/10.3390/cells8080806DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6721529PMC
July 2019

PKCα-Mediated Downregulation of RhoA Activity in Depolarized Vascular Smooth Muscle: Synergistic Vasorelaxant Effect of PKCα and ROCK Inhibition.

Cell Physiol Biochem 2019 18;52(1):76-93. Epub 2019 Feb 18.

Instituto de Biomedicina de Sevilla (IBiS)/Hospital Universitario Virgen del Rocío/CSIC/ Departamento de Fisiología Médica y Biofísica, Universidad de Sevilla, Sevilla, Spain.

Background/aims: Protein kinase C (PKC)- and RhoA/Rho-associated kinase (ROCK) play important roles in arterial sustained contraction. Although depolarization-elicited RhoA/ROCK activation is accepted, the role of PKC in depolarized vascular smooth muscle cells (VSMCs) is a subject of controversy. Our aim was to study the role of PKC in arterial contraction and its interaction with RhoA/ROCK.

Methods: Mass spectrometry was used to identify the PKC isoenzymes. PKCα levels and RhoA activity were analyzed by western blot and G-LISA, respectively, and isometric force was measured in arterial rings.

Results: In depolarized VSMCs RhoA and PKCα were translocated to the plasma membrane, where they colocalize and coimmunoprecipitate. Interestingly, depolarization-induced RhoA activation was downregulated by PKCα, effect reverted by PKCα inhibition. Phorbol 12,13-dibutyrate (PDBu) induced the translocation of PKCα to the plasma membrane, increased the level of RhoA in the cytosol and reduced RhoA/ROCK activity. These effects were reverted when PKC was inhibited. Pharmacological or siRNA inhibition of PKCα synergistically potentiated the vasorelaxant effect of RhoA/ROCK inhibition.

Conclusion: The present study provides the first evidence that RhoA activity is downregulated by PKCα in depolarized and PDBu treated freshly isolated VSMCs and arteries, with an important physiological role on arterial contractility.
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http://dx.doi.org/10.33594/000000006DOI Listing
March 2019

Antibiotic resistance and population structure of cystic fibrosis Pseudomonas aeruginosa isolates from a Spanish multi-centre study.

Int J Antimicrob Agents 2017 Sep 20;50(3):334-341. Epub 2017 Jul 20.

University Hospital Clinic of Valencia, University of Valencia, Valencia, Spain.

The first Spanish multi-centre study on the microbiology of cystic fibrosis (CF) was conducted from 2013 to 2014. The study involved 24 CF units from 17 hospitals, and recruited 341 patients. The aim of this study was to characterise Pseudomonas aeruginosa isolates, 79 of which were recovered from 75 (22%) patients. The study determined the population structure, antibiotic susceptibility profile and genetic background of the strains. Fifty-five percent of the isolates were multi-drug-resistant, and 16% were extensively-drug-resistant. Defective mutS and mutL genes were observed in mutator isolates (15.2%). Considerable genetic diversity was observed by pulsed-field gel electrophoresis (70 patterns) and multi-locus sequence typing (72 sequence types). International epidemic clones were not detected. Fifty-one new and 14 previously described array tube (AT) genotypes were detected by AT technology. This study found a genetically unrelated and highly diverse CF P. aeruginosa population in Spain, not represented by the epidemic clones widely distributed across Europe, with multiple combinations of virulence factors and high antimicrobial resistance rates (except for colistin).
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http://dx.doi.org/10.1016/j.ijantimicag.2017.03.034DOI Listing
September 2017

Emergence of cfr-Mediated Linezolid Resistance in a Methicillin-Resistant Staphylococcus aureus Epidemic Clone Isolated from Patients with Cystic Fibrosis.

Antimicrob Agents Chemother 2015 Dec 14;60(3):1878-82. Epub 2015 Dec 14.

Servicio de Microbiología, Hospital Universitario Ramón y Cajal and Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain Red Española de Investigación en Patología Infecciosa (REIPI), Madrid, Spain.

Resistance to linezolid (LZD) in methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients with cystic fibrosis (CF) is due mainly to ribosomal mutations. We report on four CF patients with LZD-resistant MRSA bronchopulmonary infections by strains carrying the cfr gene. Strains from one patient also harbored the G2576U mutation (23S rRNA) and the G139R substitution (L3 protein). All strains belonged to the epidemic clone ST125 MRSA IVc. Our results support the monitoring of LZD resistance emergence in CF and non-CF MRSA isolates.
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http://dx.doi.org/10.1128/AAC.02067-15DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4775957PMC
December 2015

Elevated levels of the complement activation product C4d in bronchial fluids for the diagnosis of lung cancer.

PLoS One 2015 23;10(3):e0119878. Epub 2015 Mar 23.

Program in Solid Tumors and Biomarkers, Center for Applied Medical Research (CIMA), Pamplona, Spain; Department of Biochemistry and Genetics, School of Sciences, University of Navarra, Pamplona, Spain.

Molecular markers in bronchial fluids may contribute to the diagnosis of lung cancer. We previously observed a significant increase of C4d-containing complement degradation fragments in bronchoalveolar lavage (BAL) supernatants from lung cancer patients in a cohort of 50 cases and 22 controls (CUN cohort). The present study was designed to determine the diagnostic performance of these complement fragments (hereinafter jointly referred as C4d) in bronchial fluids. C4d levels were determined in BAL supernatants from two independent cohorts: the CU cohort (25 cases and 26 controls) and the HUVR cohort (60 cases and 98 controls). A series of spontaneous sputum samples from 68 patients with lung cancer and 10 controls was also used (LCCCIO cohort). Total protein content, complement C4, complement C5a, and CYFRA 21-1 were also measured in all cohorts. C4d levels were significantly increased in BAL samples from lung cancer patients. The area under the ROC curve was 0.82 (95%CI = 0.71-0.94) and 0.67 (95%CI = 0.58-0.76) for the CU and HUVR cohorts, respectively. In addition, unlike the other markers, C4d levels in BAL samples were highly consistent across the CUN, CU and HUVR cohorts. Interestingly, C4d test markedly increased the sensitivity of bronchoscopy in the two cohorts in which cytological data were available (CUN and HUVR cohorts). Finally, in the LCCCIO cohort, C4d levels were higher in sputum supernatants from patients with lung cancer (area under the ROC curve: 0.7; 95%CI = 0.56-0.83). In conclusion, C4d is consistently elevated in bronchial fluids from lung cancer patients and may be used to improve the diagnosis of the disease.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119878PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4370816PMC
March 2016

Gene expression profile predictive of response to chemotherapy in metastatic colorectal cancer.

Oncotarget 2015 Mar;6(8):6151-9

Laboratorio de Oncología Molecular y Nuevas Terapias, Instituto de Biomedicina de Sevilla (IBIS) (HUVR, CSIC, Universidad de Sevilla), Sevilla, Spain.

Fluoropyrimidine-based chemotherapy (CT) has been the mainstay of care of metastatic colorectal cancer (mCRC) for years. Response rates are only observed, however, in about half of treated patients, and there are no reliable tools to prospectively identify patients more likely to benefit from therapy. The purpose of our study was to identify a gene expression profile predictive of CT response in mCRC. Whole genome expression analyses (Affymetrix GeneChip HG-U133 Plus 2.0) were performed in fresh frozen tumor samples of 37 mCRC patients (training cohort). Differential gene expression profiles among the two study conditions (responders versus non-responders) were assessed using supervised class prediction algorithms. A set of 161 differentially expressed genes in responders (23 patients; 62%) versus non-responders (14 patients; 38%) was selected for further assessment and validation by RT-qPCR (TaqMan Low Density Arrays (TLDA) 7900 HT Micro Fluidic Cards) in an independent multi-institutional cohort (53 mCRC patients). Seven of these genes were confirmed as significant predictors of response. Patients with a favorable predictive signature had significantly greater response rate (58% vs. 13%, p = 0.024), progression-free survival (61% vs. 13% at 1 year, HR = 0.32, p = 0.009) and overall survival (32 vs. 16 months, HR = 0.21, p = 0.003) than patients with an unfavorable gene signature. This is the first study to validate a gene-expression profile predictive of response to CT in mCRC patients. Larger and prospective confirmatory studies are required, however, in order to successfully provide oncologists with adequate tools to optimize treatment selection in routine clinical practice.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4467428PMC
http://dx.doi.org/10.18632/oncotarget.3152DOI Listing
March 2015

Spanish consensus on the prevention and treatment of Pseudomonas aeruginosa bronchial infections in cystic fibrosis patients.

Arch Bronconeumol 2015 Mar 20;51(3):140-50. Epub 2015 Jan 20.

Unidad de Trasplante Pulmonar y Fibrosis Quística, Hospital Universitario y Politécnico la Fe, Valencia, España. Electronic address:

Pseudomonas aeruginosa is the main pathogen in bronchopulmonary infections in cystic fibrosis (CF) patients. It can only be eradicated at early infection stages while reduction of its bacterial load is the therapeutic goal during chronic infection or exacerbations. Neonatal screening and pharmacokinetic/pharmacodynamic knowledge has modified the management of CF-patients. A culture based microbiological follow-up should be performed in patients with no infection with P.aeruginosa. At initial infection, inhaled colistin (0,5-2MU/tid), tobramycin (300mg/bid) or aztreonam (75mg/tid) with or without oral ciprofloxacin (15-20mg/kg/bid, 2-3weeks) are recommended. In chronic infections, treatment is based on continuous administration of colistin or with a 28-day on-off regimen with tobramycin or aztreonam. During mild-moderate exacerbations oral ciprofloxacin (2-3weeks) can be administered while serious exacerbations must be treated with intravenous combination therapy (beta-lactam with an aminoglycoside or a fluoroquinolone). Future studies will support antibiotic rotation and/or new combination therapies. Epidemiological measures are also recommended to avoid new P.aeruginosa infections and "patient-to-patient transmission" of this pathogen.
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http://dx.doi.org/10.1016/j.arbres.2014.09.021DOI Listing
March 2015

MiR-107 and miR-99a-3p predict chemotherapy response in patients with advanced colorectal cancer.

BMC Cancer 2014 Sep 7;14:656. Epub 2014 Sep 7.

Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocio/CSIC/Universidad de Sevilla, Manuel Siurot s/n, 41013 Seville, Spain.

Background: MicroRNAs (miRNAs) are involved in numerous biological and pathological processes including colorectal cancer (CRC). The aim of our study was to evaluate the ability of miRNA expression patterns to predict chemotherapy response in a cohort of 78 patients with metastatic CRC (mCRC).

Methods: We examined expression levels of 667 miRNAs in the training cohort and evaluated their potential association with relevant clinical endpoints. We identified a miRNA profile that was analysed by RT-qPCR in an independent cohort. For a set of selected miRNAs, bioinformatic target predictions and pathway analysis were also performed.

Results: Eight miRNAs (let-7 g*, miR-107, miR-299-5p, miR-337-5p, miR-370, miR-505*, miR-889 and miR-99a-3p) were significant predictors of response to chemotherapy in the training cohort. In addition, overexpression of miR-107, miR-337-5p and miR-99a-3p, and underexpression of miR-889, were also significantly associated with improved progression-free and/or overall survival. MicroRNA-107 and miR-99a-3p were further validated in an independent cohort as predictive markers for chemotherapy response. In addition, an inverse correlation was confirmed in our study population between miR-107 levels and mRNA expression of several potential target genes (CCND1, DICER1, DROSHA and NFKB1).

Conclusions: MiR-107 and miR-99a-3p were validated as predictors of response to standard fluoropyrimidine-based chemotherapy in patients with mCRC.
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http://dx.doi.org/10.1186/1471-2407-14-656DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4167263PMC
September 2014

MicroRNA-dependent regulation of transcription in non-small cell lung cancer.

PLoS One 2014 13;9(3):e90524. Epub 2014 Mar 13.

Molecular Oncology and New Therapies Group. Instituto de Biomedicina de Sevilla (IBIS) (HUVR, CSIC, Universidad de Sevilla), Sevilla, Spain; Medical Oncology Department, Hospital Universitario Virgen del Rocio, Sevilla, Spain.

Squamous cell lung cancer (SCC) and adenocarcinoma are the most common histological subtypes of non-small cell lung cancer (NSCLC), and have been traditionally managed in the clinic as a single entity. Increasing evidence, however, illustrates the biological diversity of these two histological subgroups of lung cancer, and supports the need to improve our understanding of the molecular basis beyond the different phenotypes if we aim to develop more specific and individualized targeted therapy. The purpose of this study was to identify microRNA (miRNA)-dependent transcriptional regulation differences between SCC and adenocarcinoma histological lung cancer subtypes. In this work, paired miRNA (667 miRNAs by TaqMan Low Density Arrays (TLDA)) and mRNA profiling (Whole Genome 44 K array G112A, Agilent) was performed in tumor samples of 44 NSCLC patients. Nine miRNAs and 56 mRNAs were found to be differentially expressed in SCC versus adenocarcinoma samples. Eleven of these 56 mRNA were predicted as targets of the miRNAs identified to be differently expressed in these two histological conditions. Of them, 6 miRNAs (miR-149, miR-205, miR-375, miR-378, miR-422a and miR-708) and 9 target genes (CEACAM6, CGN, CLDN3, ABCC3, MLPH, ACSL5, TMEM45B, MUC1) were validated by quantitative PCR in an independent cohort of 41 lung cancer patients. Furthermore, the inverse correlation between mRNAs and microRNAs expression was also validated. These results suggest miRNA-dependent transcriptional regulation differences play an important role in determining key hallmarks of NSCLC, and may provide new biomarkers for personalized treatment strategies.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0090524PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3953115PMC
January 2016

Identification of oxidative stress related proteins as biomarkers for lung cancer and chronic obstructive pulmonary disease in bronchoalveolar lavage.

Int J Mol Sci 2013 Feb 6;14(2):3440-55. Epub 2013 Feb 6.

Biomedicine Institute of Seville, Seville 41013, Spain.

Lung cancer (LC) and chronic obstructive pulmonary disease (COPD) commonly coexist in smokers, and the presence of COPD increases the risk of developing LC. Cigarette smoke causes oxidative stress and an inflammatory response in lung cells, which in turn may be involved in COPD and lung cancer development. The aim of this study was to identify differential proteomic profiles related to oxidative stress response that were potentially involved in these two pathological entities. Protein content was assessed in the bronchoalveolar lavage (BAL) of 60 patients classified in four groups: COPD, COPD and LC, LC, and control (neither COPD nor LC). Proteins were separated into spots by two dimensional polyacrylamide gel electrophoresis (2D-PAGE) and examined by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/TOF). A total of 16 oxidative stress regulatory proteins were differentially expressed in BAL samples from LC and/or COPD patients as compared with the control group. A distinct proteomic reactive oxygen species (ROS) protein signature emerged that characterized lung cancer and COPD. In conclusion, our findings highlight the role of the oxidative stress response proteins in the pathogenic pathways of both diseases, and provide new candidate biomarkers and predictive tools for LC and COPD diagnosis.
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http://dx.doi.org/10.3390/ijms14023440DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3588051PMC
February 2013

Paediatric patients with a tracheostomy: a multicentre epidemiological study.

Eur Respir J 2012 Dec 10;40(6):1502-7. Epub 2012 Apr 10.

Hospital Carlos Haya y Universidad de Málaga, Malaga, Spain.

Changes in the indications for tracheostomy in children have led to the progressively greater involvement of the paediatric pulmonologist in the care of these patients. The aim of this study was to review the current profile of tracheostomised children in Spain. We undertook a longitudinal, multicentre study over 2 yrs (2008 and 2009) of all patients aged between 1 day and 18 yrs who had a tracheostomy. The study, involving 18 Spanish hospitals, included 249 patients, of whom 150 (60.2%) were <1 yr of age. The main indications for the procedure were prolonged ventilation (n=156, 62.6%), acquired subglottic stenosis (n=34, 13.6%), congenital or acquired craniofacial anomalies (n=25, 10%) and congenital airway anomalies (n=24, 9.6%). The most frequent underlying disorders were neurological diseases (n=126, 50.6%) and respiratory diseases (n=98, 39.3%). Over the 2-yr study period, 92 (36.9%) children required ventilatory support, and decannulation was achieved in 59 (23.7%). Complications arose in 117 patients (46.9%). Mortality attributed to the underlying condition was 12.5% and that related directly to the tracheostomy was 3.2%. Respiratory complexity of tracheostomised children necessitates prolonged, multidisciplinary follow-up, which can often extend to adulthood.
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http://dx.doi.org/10.1183/09031936.00164611DOI Listing
December 2012

Association between the miRNA signatures in plasma and bronchoalveolar fluid in respiratory pathologies.

Dis Markers 2012 ;32(4):221-30

Department of Medical Oncology, University Hospital Virgen del Rocío, Instituto de Biomedicina de Sevilla, Seville, Spain.

The identification of new less invasive biomarkers is necessary to improve the detection and prognostic outcome of respiratory pathological processes. The measurement of miRNA expression through less invasive techniques such as plasma and serum have been suggested to analysis of several lung malignancies including lung cancer. These studies are assuming a common deregulated miRNA expression both in blood and lung tissue. The present study aimed to obtain miRNA representative signatures both in plasma and bronchoalveolar cell fraction that could serve as biomarker in respiratory diseases. Ten patients were evaluated to assess the expression levels of 381 miRNAs. We found that around 50% miRNAs were no detected in both plasma and bronchoalveolar cell fraction and only 20% of miRNAs showed similar expression in both samples. These results show a lack of association of miRNA signatures between plasma and bronchoalveolar cytology in the same patient. The profiles are not comparable; however, there is a similarity in the relative expression in a very small subset of miRNAs (miR-17, miR-19b, miR-195 and miR-20b) between both biological samples in all patients. This finding supports that the miRNAs profiles obtained from different biological samples have to be carefully validated to link with respiratory diseases.
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http://dx.doi.org/10.3233/DMA-2011-0882DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3826892PMC
July 2012

Down-regulation of spinophilin in lung tumours contributes to tumourigenesis.

J Pathol 2011 Sep 19;225(1):73-82. Epub 2011 May 19.

Instituto de Biomedicina de Sevilla, IBIS/HUVR Sevilla, Spain.

The scaffold protein spinophilin (Spn, PPP1R9B) is one of the regulatory subunits of phosphatase-1a (PP1), targeting it to distinct subcellular locations and to its target. Loss of Spn reduces PPP1CA levels, thereby maintaining higher levels of phosphorylated pRb. This effect contributes to an increase in p53 activity. However, in the absence of p53, reduced levels of Spn increase the tumourigenic properties of cells. In addition, Spn knockout mice have a reduced lifespan, an increased number of tumours and increased cellular proliferation in some tissues, such as the mammary ducts. In addition, the combined loss of Spn and p53 activity leads to an increase in mammary carcinomas, confirming the functional relationship between p53 and Spn. In this paper, we report that Spn is absent in 20% and reduced in another 37% of human lung tumours. Spn reduction correlates with malignant grade. Furthermore, the loss of Spn also correlates with p53 mutations. Analysis of miRNAs in a series of lung tumours showed that miRNA106a* targeting Spn is over-expressed in some patients, correlating with decreased Spn levels. Proof-of-concept experiments over-expressing miRNA106a* or Spn shRNA in lung tumour cells showed increased tumourigenicity. In conclusion, our data showed that miRNA106a* over-expression found in lung tumours might contribute to tumourigenesis through Spn down-regulation in the absence of p53.
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http://dx.doi.org/10.1002/path.2905DOI Listing
September 2011

Caspase-11 mediates ischemia-induced astrocyte death: involvement of endoplasmic reticulum stress and C/EBP homologous protein.

J Neurosci Res 2010 Apr;88(5):1094-105

Departamento de Ciencias Médicas and Centro Regional de Investigaciones Biomédicas, Facultad de Medicina, Universidad de Castilla-La Mancha, Albacete, Spain.

Astrocytes are essential cells for maintaining brain integrity. We have recently shown that the transcription factor C/EBP homologous protein (CHOP), associated with endoplasmic reticulum (ER) stress, plays a key role in the astrocyte death induced by ischemia. Meanwhile, mediators of apoptosis downstream of CHOP in the ER stress-dependent pathway remain to be elucidated. Our aim in this work was to determine whether caspase-11, able to activate apoptotic and proinflammatory pathways, is implicated in ER stress-dependent astrocyte death in ischemic conditions. According to our results, caspase-11 is up-regulated in primary astrocyte cultures following either oxygen and glucose deprivation (OGD) or treatment with the ER-stress inducers thapsigargin and tunicamycin. Moreover, these same stimuli increased caspase-11 mRNA levels and luciferase activity driven by a caspase-11 promoter, indicating that caspase-11 is regulated at the transcriptional level. Our data also illustrate the involvement of ER stress-associated CHOP in caspase-11 regulation, insofar as CHOP overexpression by means of an adenoviral vector caused a significant raise in caspase-11. In turn, caspase-11 suppression with siRNA rescued astrocytes from OGD- and ER stress-induced death, supporting the idea that caspase-11 is responsible for the deleterious effects of ischemia on astrocytes. Finally, inhibition of caspase-1 and caspase-3 significantly reduced astrocyte death, which indicates that these proteases act as death effectors of caspase-11. In conclusion, our work contributes to clarifying the pathways leading to astrocyte death in response to ischemia by defining caspase-11 as a key mediator of the ER stress response acting downstream of CHOP.
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http://dx.doi.org/10.1002/jnr.22280DOI Listing
April 2010

mTOR/S6 kinase pathway contributes to astrocyte survival during ischemia.

J Biol Chem 2009 Aug 17;284(33):22067-22078. Epub 2009 Jun 17.

Department of Medical Sciences, Medical School, Universidad de Castilla La Mancha, 02006 Albacete, Spain.

Neurons are highly dependent on astrocyte survival during brain damage. To identify genes involved in astrocyte function during ischemia, we performed mRNA differential display in astrocytes after oxygen and glucose deprivation (OGD). We detected a robust down-regulation of S6 kinase 1 (S6K1) mRNA that was accompanied by a sharp decrease in protein levels and activity. OGD-induced apoptosis was increased by the combined deletion of S6K1 and S6K2 genes, as well as by treatment with rapamycin that inhibits S6K1 activity by acting on the upstream regulator mTOR (mammalian target of rapamycin). Astrocytes lacking S6K1 and S6K2 (S6K1;S6K2-/-) displayed a defect in BAD phosphorylation and in the expression of the anti-apoptotic factors Bcl-2 and Bcl-xL. Furthermore reactive oxygen species were increased while translation recovery was impaired in S6K-deficient astrocytes following OGD. Rescue of either S6K1 or S6K2 expression by adenoviral infection revealed that protective functions were specifically mediated by S6K1, because this isoform selectively promoted resistance to OGD and reduction of ROS levels. Finally, "in vivo" effects of S6K suppression were analyzed in the permanent middle cerebral artery occlusion model of ischemia, in which absence of S6K expression increased mortality and infarct volume. In summary, this article uncovers a protective role for astrocyte S6K1 against brain ischemia, indicating a functional pathway that senses nutrient and oxygen levels and may be beneficial for neuronal survival.
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http://dx.doi.org/10.1074/jbc.M109.033100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2755931PMC
August 2009

SEPS1 gene is activated during astrocyte ischemia and shows prominent antiapoptotic effects.

J Mol Neurosci 2008 Jul 23;35(3):259-65. Epub 2008 May 23.

Pharmacology Unit, Facultad de Medicina, Departamento de Ciencias Médicas and Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, Albacete, Spain.

Contrarily to neurons, astrocytes can survive short periods of ischemia. We have searched for genes implicated in astrocyte resistance to ischemia using oxygen and glucose deprivation (OGD) as a stroke model. A RNA differential display approach uncovered the OGD induction of selenoprotein-S-encoding gene SEPS1. This endoplasmic reticulum (ER) resident protein is known to promote cell survival regulating the ER stress as well as inflammation. We found that suppression of SEPS1 by small interfering RNA severely increases astrocyte injure caused by OGD, suggesting that selenoprotein S protects astrocytes against ischemia. Our data also support that modulation of ER stress is implicated in this effect.
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http://dx.doi.org/10.1007/s12031-008-9069-3DOI Listing
July 2008