Fortes, P. (Puri)

Filtering

2003 - 2009162010 - 20209

Settings

Author search.filters.isAuthorOfPublication.4b719a39-983d-402a-bb2a-2bdd276be18e

Search Results

Now showing 1 - 10 of 25
  • No Thumbnail Available
    microRNA-451 regulates macrophage migration inhibitory factor production and proliferation of gastrointestinal cancer cells
    (American Association of Cancer Research, 2009-04-01) Bitarte, N. (Nerea); Agorreta, J. (Jackeline); Zarate, R. (Ruth); Rodriguez, J. (Javier); Bandres, E. (Eva); Ramirez, N. (Natalia); Garcia-Foncillas, J. (Jesús); Jimenez, P. (P.); Fortes, P. (Puri); Arias, F. (F.); Aguirre-Ena, X. (Xabier); Diaz-Gonzalez, J.A. (Juan Antonio); Sola, J.J. (Jesús Javier)
    Purpose:microRNAs (miRNA) are small RNAs that function as post-transcriptional regulators of gene expression.R ecent evidence has shown that somemiRNAs can act as oncogenes or tumor suppressors.This study was conducted to evaluate the potential association of miRNA expression with clinical outcome in patients with gastric cancer. Experimental Design: Expression of 250 human mature miRNAs was measured by real-time PCR on paraffin-embedded tumor samples of 21patients with gastric cancer stage III uniformly treated with surgical resection followed by chemoradiation.We identified the miRNAs correlated with disease-free and overall survival times, and the results were evaluated including 24 other patients. In vitro cell proliferation and radiosensitivity studies were done to support clinical data. Results:The results revealed that down-regulation ofmiR-451was associatedwithworse prognosis. m iR-451was detected by in situ hybridization in epithelial cells and showed decreased expression in gastric and colorectal cancer versus nontumoral tissues.O verexpression of miR-451in gastric and colorectal cancer cells reduced cell proliferation and increased sensitivity to radiotherapy.Microarray and bioinformatic analysis identified the novel oncogene macrophage migration inhibitory factor (MIF) as a potential target of miR-451.In fact, overexpression of miR- 451down-regulatedmRNA and proteinlevels ofMIF and decreased expression of reporter genes with MIF target sequences.M oreover, we found a significant inverse correlation between miR- 451and MIF expression in tumoral gastric biopsies. Conclusions:These findings support the role ofmiR-451as a regulatorof cancerproliferationand opennewperspectives for thedevelopmentof effectivetherapies forchemoradioresistantcancers
  • Thumbnail Image
    LncRNAs in HCV Infection and HCV-Related Liver Disease
    (MDPI AG, 2020) Unfried, J.P. (Juan P.); Fortes, P. (Puri)
    Long non-coding RNAs (lncRNAs) are transcripts with poor coding capacity that may interact with proteins, DNA, or other RNAs to perform structural and regulatory functions. The lncRNA transcriptome changes significantly in most diseases, including cancer and viral infections. In this review, we summarize the functional implications of lncRNA-deregulation after infection with hepatitis C virus (HCV). HCV leads to chronic infection in many patients that may progress to liver cirrhosis and hepatocellular carcinoma (HCC). Most lncRNAs deregulated in infected cells that have been described function to potentiate or block the antiviral response and, therefore, they have a great impact on HCV viral replication. In addition, several lncRNAs upregulated by the infection contribute to viral release. Finally, many lncRNAs have been described as deregulated in HCV-related HCC that function to enhance cell survival, proliferation, and tumor progression by different mechanisms. Interestingly, some HCV-related HCC lncRNAs can be detected in bodily fluids, and there is great hope that they could be used as biomarkers to predict cancer initiation, progression, tumor burden, response to treatment, resistance to therapy, or tumor recurrence. Finally, there is high confidence that lncRNAs could also be used to improve the suboptimal long-term outcomes of current HCC treatment options.
  • Thumbnail Image
    Regulation of the Interferon Response by lncRNAs in HCV Infection
    (Frontiers Media, 2018) Fortes, P. (Puri); Valadkhan, S. (Saba)
    The interferon (IFN) response is a critical component of the innate immunity antiviral pathways in mammalians. IFN signaling results in increased expression of cellular factors that block key steps in the viral replication cycle. Many IFN-induced antiviral factors act through decreasing viral entry, replication, transcription, translation, packaging and release. However, these effects are also deleterious for the viability of the cell, which necessitates a tight control over the magnitude and duration of the IFN response. This is partially achieved through the IFN-mediated activation of negative regulatory factors that help in termination of the IFN response and return to a normal homeostatic state. Such built-in negative regulatory mechanisms are frequently hijacked by viruses such as the Hepatitis C virus (HCV) to increase viral replication and productive infections. We and others have shown that long non-coding RNAs (lncRNAs) play prominent roles in regulation of the IFN response. Activation of the IFN cascade alters the expression of a large number of lncRNAs, many of which are directly induced by the JAK/STAT pathway and thus, resemble the well-studied protein-coding interferon-stimulated genes (ISGs). While only a handful of IFN- and virally induced lncRNAs have been characterized, recent studies have identified several lncRNAs that act as positive or negative regulators of expression of ISGs during the IFN response. A number of such regulatory lncRNAs have multiple ISG targets, while others act on a single neighboring ISG. Another group of studied lncRNAs act further upstream and regulate the expression of IFN genes or factors that sense the presence of viral genome or replication products. The large number of unstudied IFN- and virally induced lncRNAs makes it highly likely that future studies will reveal a much greater share for this class of transcripts in regulation of the antiviral response. In addition to their physiological roles, the expression of such lncRNAs is frequently modulated by virally encoded factors to interfere with the antiviral response and promote viral replication, thus making them ideal targets for therapeutic intervention.
  • Thumbnail Image
    Durable cytotoxic immune responses against gp120 elicited by recombinant SV40 vectors encoding HIV-1 gp120 +/- IL-15
    (BioMed Central, 2004) T'sao, P.Y. (Patricia Y.); Vera, M. (María); McKee, H.J. (Harley J.); Fortes, P. (Puri); Strayer, D.S. (David S.)
    BACKGROUND: A vaccine that elicits durable, powerful anti-HIV immunity remains an elusive goal. In these studies we tested whether multiple treatments with viral vector-delivered HIV envelope antigen (gp120), with and without IL-15, could help to approach that goal. For this purpose, we used recombinant Tag-deleted SV40-derived vectors (rSV40s), since they do not elicit neutralizing antibody responses, and so can be given multiply without loss of transduction efficiency. METHODS: SV(gp120) carried the coding sequences for HIV-1NL4-3 Env, and SV(mIL-15) carried the cDNA for mouse IL-15. Singly, and in combination, these two vectors were given monthly to BALB/cJ mice. Cytotoxic immunity and cytotoxic memory were tested in direct cytotoxicity assays using unselected effector cells. Antibody vs. gp120 was measured in a binding assay. In both cases, targets were P815 cells that were stably transfected with gp120. RESULTS: Multiple injections of SV(gp120) elicited powerful anti-gp120 cytolytic activity (>70% specific lysis) by unselected spleen cells. Cells from multiply-immunized mice that were rested 1 year after their last injections still showed >60% gp120-specific lysis. Anti-gp120 antibody was first detected after 2 monthly injections of SV(gp120) and remained elevated thereafter. Adding SV(mIL-15) to the immunization regimen dramatically accelerated the development of memory cytolytic responses, with >/= 50% specific lysis seen 1 month after two treatments. IL-15 did not alter the development of antibody responses. CONCLUSIONS: Thus, rSV40s encoding antigens and immunostimulatory cytokines may be useful tools for priming and/or boosting immune responses against HIV.
  • Thumbnail Image
    Down-Regulation of hsa-miR-10a in Chronic Myeloid Leukemia CD34+ Cells Increases USF2-Mediated Cell Growth
    (American Association for Cancer Research, 2008) Vilas, A. (Amaia); Cordeu, L. (Lucía); Jimenez-Velasco, A. (A.); Aparicio, O. (Óscar); Roman-Gomez, J. (José); San-Jose-Eneriz, E. (Edurne); Heiniger, A. (A.); Garate, L. (Leire); Navarro, G. (Germán); Bandres, E. (Eva); Garcia-Foncillas, J. (Jesús); Fortes, P. (Puri); Prosper-Cardoso, F. (Felipe); Calasanz-Abinzano, M.J. (Maria Jose); Aguirre-Ena, X. (Xabier); Perez-Roger, I. (Ignacio); Saez, B. (Borja)
    MicroRNAs (miRNA) are small noncoding, single-stranded RNAs that inhibit gene expression at a posttranscriptional level, whose abnormal expression has been described in different tumors. The aim of our study was to identify miRNAs potentially implicated in chronic myeloid leukemia (CML). We detected an abnormal miRNA expression profile in mononuclear and CD34+ cells from patients with CML compared with healthy controls. Of 157 miRNAs tested, hsa-miR-10a, hsa-miR-150, and hsa-miR-151 were down-regulated, whereas hsa-miR-96 was up-regulated in CML cells. Down-regulation of hsa-miR-10a was not dependent on BCR-ABL1 activity and contributed to the increased cell growth of CML cells. We identified the upstream stimulatory factor 2 (USF2) as a potential target of hsa-miR-10a and showed that overexpression of USF2 also increases cell growth. The clinical relevance of these findings was shown in a group of 85 newly diagnosed patients with CML in which expression of hsa-miR-10a was down-regulated in 71% of the patients, whereas expression of USF2 was up-regulated in 60% of the CML patients, with overexpression of USF2 being significantly associated with decreased expression of hsa-miR-10a (P = 0.004). Our results indicate that down-regulation of hsa-miR-10a may increase USF2 and contribute to the increase in cell proliferation of CML implicating a miRNA in the abnormal behavior of CML.
  • No Thumbnail Available
    Epigenetic Silencing of the Tumor Suppressor MicroRNA Hsa-miR-124a Regulates CDK6 Expression and Confers a Poor Prognosis in Acute Lymphoblastic Leukemia
    (American Association for Cancer Research, 2009) Vilas, A. (Amaia); Cordeu, L. (Lucía); Jimenez-Velasco, A. (A.); Roman-Gomez, J. (José); San-Jose-Eneriz, E. (Edurne); Martin, V. (Vanesa); Heiniger, A. (A.); Garate, L. (Leire); Rifon, J. J. (Jose J.); Bandres, E. (Eva); Siebert, R. (Reiner); Rodriguez-Otero, P. (Paula); Fortes, P. (Puri); Prosper-Cardoso, F. (Felipe); Torres, A. (Antonio); Calasanz-Abinzano, M.J. (Maria Jose); Aguirre-Ena, X. (Xabier); Abizanda-Sarasa, G. (Gloria); Martin-Subero, J.I. (Jose Ignacio)
    Whereas transcriptional silencing of genes due to epigenetic mechanisms is one of the most important alterations in acute lymphoblastic leukemia (ALL), some recent studies indicate that DNA methylation contributes to down-regulation of miRNAs during tumorigenesis.T o explore the epigenetic alterations of miRNAs in ALL, we analyzed the methylation and chromatin status of the miR-124a loci in ALL.E xpression of miR-124a was down-regulated in ALL by hypermethylation of the promoter and histone modifications including decreased levels of 3mk4H3 and AcH3 and increased levels of 2mK9H3, 3mK9H3, and 3mK27H3.Epigenetic down-regulation of miR-124a induced an up-regulation of its target, CDK6, and phosphorylation of retinoblastoma (Rb) and contributed to the abnormal proliferation of ALL cells both in vitro and in vivo.Cyc lin-dependent kinase 6 (CDK6) inhibition by sodium butyrate or PD-0332991 decreased ALL cell growth in vitro, whereas overexpression of pre-miR124a led to decreased tumorigenicity in a xenogeneic in vivo Rag2 / ;c / mouse model.The clinical implications of these findings were analyzed in a group of 353 patients diagnosed with ALL.M ethylation of hsa-miR-124a was observed in 59% of the patients, which correlated with down-regulation of miR-124a (P < 0.001). Furthermore, hypermethylation of hsa-miR-124a was associated with higher relapse rate (P = 0.001) and mortality rate (P < 0.001), being an independent prognostic factor for disease-free survival (P < 0.001) and overall survival (P = 0.005) in the multivariate analysis.These results provide the grounds for new therapeutic strategies in ALL either targeting the epigenetic regulation of microRNAs and/or directly targeting the CDK6-Rb pathway.
  • Thumbnail Image
    Requirements for gene silencing mediated by U1 snRNA binding to a target sequence
    (Oxford University Press, 2008) Oswald, E. (Evelyn); Amin, V. (Vaibhav); Vera, M. (María); Gunderson, S.I. (Samuel I.); Abad, X. (Xabier); Fortes, P. (Puri); Jung, S.P. (Stephen P.); Romero, I. (Inés)
    U1 interference (U1i) is a novel method to block gene expression. U1i requires expression of a 5'-end-mutated U1 snRNA designed to base pair to the 3'-terminal exon of the target gene's pre-mRNA that leads to inhibition of polyadenylation. Here, we show U1i is robust (> or =95%) and a 10-nt target length is sufficient for good silencing. Surprisingly, longer U1 snRNAs, which could increase annealing to the target, fail to improve silencing. Extensive mutagenesis of the 10-bp U1 snRNA:target duplex shows that any single mismatch different from GU at positions 3-8, destroys silencing. However, mismatches within the other positions give partial silencing, suggesting that off-target inhibition could occur. The specificity of U1i may be enhanced, however, by the fact that silencing is impaired by RNA secondary structure or by splicing factors binding nearby, the latter mediated by Arginine-Serine (RS) domains. U1i inhibition can be reconstituted in vivo by tethering of RS domains of U1-70K and U2AF65. These results help to: (i) define good target sites for U1i; (ii) identify and understand natural cellular examples of U1i; (iii) clarify the contribution of hydrogen bonding to U1i and to U1 snRNP binding to 5' splice sites and (iv) understand the mechanism of U1i.
  • Thumbnail Image
    Methionine adenosyltransferase II beta subunit gene expression provides a proliferative advantage in human hepatoma
    (WB Saunders, 2003) Latasa, M.U. (María Ujué); Martin-Duce, A. (Antonio); Avila, M.A. (Matías Antonio); Ruiz Garcia-Trevijano, E. (Elena); Fortes, P. (Puri); Caballeria, J. (Juan); Mato, J.M. (José María); Martinez-Chantar, M.L. (María Luz)
    BACKGROUND & AIMS: Of the 2 genes (MAT1A, MAT2A) encoding methionine adenosyltransferase, the enzyme that synthesizes S-adenosylmethionine, MAT1A, is expressed in liver, whereas MAT2A is expressed in extrahepatic tissues. In liver, MAT2A expression associates with growth, dedifferentiation, and cancer. Here, we identified the beta subunit as a regulator of proliferation in human hepatoma cell lines. The beta subunit has been cloned and shown to lower the K(m) of methionine adenosyltransferase II alpha2 (the MAT2A product) for methionine and to render the enzyme more susceptible to S-adenosylmethionine inhibition. METHODS: Methionine adenosyltransferase II alpha2 and beta subunit expression was analyzed in human and rat liver and hepatoma cell lines and their interaction studied in HuH7 cells. beta Subunit expression was up- and down-regulated in human hepatoma cell lines and the effect on DNA synthesis determined. RESULTS: We found that beta subunit is expressed in rat extrahepatic tissues but not in normal liver. In human liver, beta subunit expression associates with cirrhosis and hepatoma. beta Subunit is expressed in most (HepG2, PLC, and Hep3B) but not all (HuH7) hepatoma cell lines. Transfection of beta subunit reduced S-adenosylmethionine content and stimulated DNA synthesis in HuH7 cells, whereas down-regulation of beta subunit expression diminished DNA synthesis in HepG2. The interaction between methionine adenosyltransferase II alpha2 and beta subunit was demonstrated in HuH7 cells. CONCLUSIONS: Our findings indicate that beta subunit associates with cirrhosis and cancer providing a proliferative advantage in hepatoma cells through its interaction with methionine adenosyltransferase II alpha2 and down-regulation of S-adenosylmethionine levels.
  • Thumbnail Image
    Adenovirus virus-associated RNA is processed to functional interfering RNAs involved in virus production
    (American Society for Microbiology, 2006) Aparicio, O. (Óscar); Zaratiegui, M. (Mikel); Narvaiza, I. (Íñigo); Razquin, N. (Nerea); Fortes, P. (Puri)
    Posttranscriptional gene silencing allows sequence-specific control of gene expression. Specificity is guaranteed by small antisense RNAs such as microRNAs (miRNAs) or small interfering RNAs (siRNAs). Functional miRNAs derive from longer double-stranded RNA (dsRNA) molecules that are cleaved to pre-miRNAs in the nucleus and are transported by exportin 5 (Exp 5) to the cytoplasm. Adenovirus-infected cells express virus-associated (VA) RNAs, which are dsRNA molecules similar in structure to pre-miRNAs. VA RNAs are also transported by Exp 5 to the cytoplasm, where they accumulate. Here we show that small RNAs derived from VA RNAs (svaRNAs), similar to miRNAs, can be found in adenovirus-infected cells. VA RNA processing to svaRNAs requires neither viral replication nor viral protein expression, as evidenced by the fact that svaRNA accumulation can be detected in cells transfected with VA sequences. svaRNAs are efficiently bound by Argonaute 2, the endonuclease of the RNA-induced silencing complex, and behave as functional siRNAs, in that they inhibit the expression of reporter genes with complementary sequences. Blocking svaRNA-mediated inhibition affects efficient adenovirus production, indicating that svaRNAs are required for virus viability. Thus, svaRNA-mediated silencing could represent a novel mechanism used by adenoviruses to control cellular or viral gene expression.
  • Thumbnail Image
    Factors influencing the production of recombinant SV40 vectors
    (Nature Publishing Group, 2004) Prieto, J. (Jesús); Vera, M. (María); Fortes, P. (Puri); Strayer, D.S. (David S.)
    Most gene therapy approaches employ viral vectors for gene delivery. Ideally, these vectors should be produced at high titer and purity with well-established protocols. Standardized methods to measure the quality of the vectors produced are imperative, as are techniques that allow reproducible quantitation of viral titer. We devised a series of protocols that achieve high-titer production and reproducible purification and provide for quality control and titering of recombinant simian virus 40 vectors (rSV40s). rSV40s are good candidate vehicles for gene transfer: they are easily modified to be nonreplicative and they are nonimmunogenic. Further, they infect a wide variety of cells and allow long-term transgene expression. We report here these protocols to produce rSV40 vectors in high yields, describe their purification, and characterize viral stocks using quality control techniques that monitor the presence of wild-type SV40 revertants and defective interfering particles. Several methods for reproducible titration of rSV40 viruses have been compared. We believe that these techniques can be widely applied to obtain high concentrations of high-quality rSV40 viruses reproducibly.