Nuestros investigadores

Javier Sáez Castresana

Bioquímica y Genética
Facultad de Ciencias. Universidad de Navarra

Publicaciones científicas más recientes (desde 2010)

Autores: RodrIguez-Losada, N.; de la Rosa Fernández-Pacheco, Francisco Javier; Larriva Hormigos, María; et al.
ISSN 2090-1232  Vol. 23  2020  págs. 37 - 45
Alpha-Synuclein (aSyn) is a chameleon-like protein. Its overexpression and intracellular deposition defines neurodegenerative alpha-synucleinopathies including Parkinson's disease. Whether aSyn upregulation is the cause or the protective reaction to alpha-synucleinopathies remains unresolved. Remarkably, the accumulation of aSyn is involved in cancer. Here, the neuroblastoma SH-SY5Y cell line was genetically engineered to overexpress aSyn at low and at high levels. aSyn cytotoxicity was assessed by the MIT and vital-dye exclusion methods, observed at the beginning of the sub-culture of low-aSyn overexpressing neurons when cells can barely proliferate exponentially. Conversely, high-aSyn overexpressing cultures grew at high rates while showing enhanced colony formation compared to low-aSyn neurons. Cytotoxicity of aSyn overexpression was indirectly revealed by the addition of pro-oxidant rotenone. Pretreatment with partially reduced graphene oxide, an apoptotic agent, increased toxicity of rotenone in low-aSyn neurons, but, it did not in high-aSyn neurons. Consistent with their enhanced proliferation, high-aSyn neurons showed elevated levels of SMP30, a senescence-marker protein, and the mitosis Ki-67 marker.
Autores: Urdiciain Ezpeleta, Alejandro; Erausquin, E.; Meléndez, B.; et al.
ISSN 1019-6439  Vol. 54  Nº 5  2019  págs. 1797 - 1808
Glioblastoma or grade IV astrocytoma is the most common and lethal form of glioma. Current glioblastoma treatment strategies use surgery followed by chemotherapy with temozolomide. Despite this, numerous glioblastoma cases develop resistance to temozolomide treatments, resulting in a poor prognosis for the patients. Novel approaches are being investigated, including the inhibition of histone deacetylase 6 (HDAC6), an enzyme that deacetylates a-tubulin, and whose overexpression in glioblastoma is associated with the loss of primary cilia. The aim of the present study was to treat glioblastoma cells with a selective HDAC6 inhibitor, tubastatin A, to determine if the malignant phenotype may be reverted. The results demonstrated a notable increase in acetylated a-tubulin levels in treated cells, which associated with downregulation of the sonic hedgehog pathway, and may hypothetically promote ciliogenesis in those cells. Treatment with tubastatin A also reduced glioblastoma clonogenicity and migration capacities, and accelerated temozolomide-induced apoptosis. Finally, HDAC6 inhibition decreased the expression of mesenchymal markers, contributing to reverse epithelial-mesenchymal transition in glioblastoma cells.
Autores: Tayyab, M.; Shahi, M. H., (Autor de correspondencia); Farheen, S.; et al.
ISSN 0360-4012  Vol. 96  Nº 1  2018  págs. 53 - 62
There are various theories to explain the pathophysiology of depression and support its diagnosis and treatment. The roles of monoamines, brain-derived neurotrophic factor (BDNF), and Wnt signaling are well researched, but sonic hedgehog (Shh) signaling and its downstream transcription factor Gli1 are not well studied in depression. Shh signaling plays a fundamental role in embryonic development and adult hippocampal neurogenesis and also involved in the growth of cancer. In this article, we summarize the evidence for the Shh signaling pathway in depression and the potential crosstalk of Shh with Wnt and BDNF. Antidepressants are known to upregulate the adult hippocampal neurogenesis to treat depression. Shh plays an important role in adult hippocampal neurogenesis, and its downstream signaling components regulate the synthesis of Wnt proteins. Moreover, the expression of Gli1 and Smo is downregulated in depression. BDNF and Wnt signaling are also regulated by various available antidepressants, so there is the possibility that Shh may be involved in the pathophysiology of depression. Therefore, the crosstalk between the Shh, Wnt, and BDNF signaling pathways is being discussed to identify the potential targets. Specifically, the potential role of the Shh signaling pathway in depression is explored as a new target for better therapies for depression.
Autores: Cantero, D.; Rodríguez de Lope, A.; Moreno de la Presa, R.; et al.
ISSN 0022-3069  Vol. 77  Nº 8  2018  págs. 710 - 716
Glioblastoma (GBM) is the most common malignant adult primary brain tumor. Despite its high lethality, a small proportion of patients have a relatively long overall survival (OS). Here we report a study of a series of 74 GBM samples from 29 long-term survivors ([LTS] OS >= 36 months) and 45 non-LTS. Using next-generation sequencing, we analyzed genetic alterations in the genes most frequently altered in gliomas. Approximately 20% of LTS had a mutation in the IDH1 or IDH2 (IDH) genes, denoting the relevance of this molecular prognostic factor. A new molecular group of GBMs harbored alterations in ATRX or DAXX genes in the absence of driver IDH or H3F3A mutations. These patients tended to have a slightly better prognosis, to be younger at diagnosis, and to present frontal or temporal tumors, and, morphologically, to present giant tumor cells. A significant fraction of LTS GBM patients had tumors with 1 or more alterations in the relevant GBM signaling pathways (RTK/PI3K, TP53 and RB1). In these patients, the PDGFRA alteration is suggested to be a favorable molecular factor. Our findings here are relevant for developing future targeted therapies and for identifying molecular prognostic factors in GBM patients.
Autores: Urdiciain Ezpeleta, Alejandro; Melendez, B.; Rey, J. A.; et al.
ISSN 2075-4655  Vol. 2  Nº 1  2018 
Glioblastoma is the most common form of glioma, as well as the most aggressive. Patients suffering from this disease have a very poor prognosis. Surgery, radiotherapy, and temozolomide are the only approved treatments nowadays. Panobinostat is a pan-inhibitor of histone deacetylases (HDACs) that has been shown to break some pathways which play an important role in cancer development. A global intention of using panobinostat as a therapeutic agent against glioblastoma is beginning to be a reality. We have treated the LN405 glioblastoma cell line with temozolomide, panobinostat, and combined treatment, in order to test apoptosis, colony formation, and a possible molecular reversion of the mesenchymal phenotype of the cells to an epithelial one. Our results show that panobinostat decreased N-cadherin levels in the LN405 glioblastoma cell line while it increased the expression of E-cadherin, which might be associated with a mesenchymal-epithelial transition in glioblastoma cells. Colony formation was reduced, and apoptosis was increased with treatments. Our research highlights the importance of panobinostat as a potential adjuvant therapy to be used with temozolomide to treat glioblastoma and the advantages of the combined treatment versus temozolomide alone, which is currently the first-line treatment used to treat this tumor.
Autores: Shahi, M. H.; Farheen, S.; Mariyath, M. P.; et al.
ISSN 1010-4283  Vol. 37  Nº 11  2016  págs. 15107 - 15114
Chemoresistance is a common hurdle for the proper treatment of gliomas. The role of Shh-Gli1 signaling in glioma progression has been reported. However, its role in glioma chemoresistance has not been well studied yet. In this work, we found that Shh-Gli1 signaling regulates the expression of one stem cell marker, BMI1 (B cell-specific Moloney murine leukemia virus), in glioma. Interestingly, we also demonstrated high expression of MRP1 (multi-drug resistance protein 1) in glioma. MRP1 expression was decreased by BMI1 siRNA and Shh-Gli1 cell signaling specific inhibitor GANT61 in our experiments. GANT61 very efficiently inhibited cell colony growth in glioma cell lines, compared to temozolomide. Moreover, a synergic effect of GANT61 and temozolomide drastically decreased the LD50 of temozolomide in the cell colony experiments. Therefore, our results suggest that there is a potential nexus of Shh-Gli1-BMI1 cell signaling to regulate MRP1 and to promote chemoresistance in glioma. Henceforth, our study opens the possibility of facing new targets, Gli1 and BMI1, for the effective treatment of glioma suppression of chemoresistance with adjuvant therapy of GANT61 and temozolomide.
Autores: Gallo Oller, Gabriel Osvaldo; Vollmann-Zwerenz, A.; Meléndez, B.; et al.
ISSN 0304-3835  Vol. 381  Nº 1  2016  págs. 67 - 75
Glioblastoma (GBM) is the most prevalent malignant primary brain tumor, accounting for 60-70% of all gliomas. Current median patient survival time is 14-16 months after diagnosis. Numerous efforts in therapy have not significantly altered the nearly uniform lethality of this malignancy. The Transforming Growth Factor beta (TGF-beta) signaling pathway plays a key role in GBM and is implicated in proliferation, invasion and therapy resistance. Several inhibitors of the TGF-beta pathway have entered clinical trials or are under development. In this work, the therapeutic potential of P144, a TGF-beta inhibitor peptide, was analyzed. P144 decreased proliferation, migration, invasiveness, and tumorigenicity in vitro, whereas apoptosis and anoikis were significantly increased for GBM cell lines. SMAD2 phosphorylation was reduced, together with a downregulation of SKI and an upregulation of SMAD7 at both transcriptional and translational levels. Additionally, P144 was able to impair tumor growth and increase survival in an in vivo flank model. Our findings suggest a potential effect of P144 in vitro and in vivo that is mediated by regulation of transcriptional target genes of the TGF-beta pathway, suggesting a therapeutic potential of P144 for GBM treatment.
Autores: de la Rosa Fernández-Pacheco, Francisco Javier; Sáenz Antoñanzas, A.; Shahi, M. H.; et al.
ISSN 1010-4283  Vol. 37  Nº 9  2016  págs. 12359 - 12370
Medulloblastoma (MB) is a highly malignant tumor of childhood. MB seems to be initiated and maintained by a small group of cells, known as cancer stem cells (CSCs). The CSC hypothesis suggests that a subset of tumor cells is able to proliferate, sustain the tumor, and develop chemoresistance, all of which make of CSC an interesting target for new anticancer therapies. The MB cell line DAOY was cultured in suspension by a medullosphere traditional culturing method and in adherent conditions by laminin-pre-coated flasks and serum-free medium enriched with specific growth factors. An increase in the stem features was shown when cells were successively cultured in hypoxia conditions. By contrast, a reduction in these properties was appreciated when cells were exposed to differentiation conditions. In addition, the CD133+ and CD133- subpopulations were isolated from cells grown in laminin-pre-coated flasks, and in vitro experiments showed that the CD133+ fraction represented the stem population and it could have CSC with a higher probability than the CD133- fraction. We can conclude that the laminin culture method in adherent conditions and the medullosphere traditional culturing method in suspension are similarly good for obtaining stem-like cells in the DAOY cell line.
Autores: Vera, B.; Martínez-Vélez, N.; Xipell Badals, Enric; et al.
Revista: PLOS ONE
ISSN 1932-6203  Vol. 11  Nº 1  2016  págs. e0147211
Despite the recent advances in the development of antitumor therapies, the prognosis for patients with malignant gliomas remains dismal. Therapy with tumor-selective viruses is emerging as a treatment option for this devastating disease. In this study we characterize the anti-glioma effect of VCN-01, an improved hyaluronidase-armed pRB-pathway-selective oncolytic adenovirus that has proven safe and effective in the treatment of several solid tumors. VCN-01 displayed a significant cytotoxic effect on glioma cells in vitro. In vivo, in two different orthotopic glioma models, a single intra-tumoral administration of VCN-01 increased overall survival significantly and led to long-term survivors free of disease.
Autores: de la Rosa Fernández-Pacheco, Francisco Javier; Iraburu, M.; Gallo Oller, Gabriel Osvaldo; et al.
ISSN 2157-2518  Vol. 7  Nº 6  2016  págs. 1000278
Glioblastoma is the most common malignant brain tumor in adults and it is currently treated with a combination of surgery, radiotherapy and chemotherapy with temozolomide (TMZ). Many patients show resistance to TMZ, which is a challenge in the treatment of this type of brain cancer. New strategies are being tested, like the inhibition of EZH2, a histone methyltransferase which is overexpressed in cancer cells, leading to angiogenesis and metastasis. In this work, the EZH2 inhibitor DZNeP was tested in A172 glioblastoma cells and in A172-TMZ-resistant glioblastoma cells. Inhibition of cell proliferation, adhesion, colony formation, and migration was noted in control and TMZresistant glioblastoma cells after DZNeP treatment. At the level of EZH2 target gene expression, DZNeP decreased EZH2 expression, and increased the expression of its target genes (E-cadherin and TIMP3), which might probably contribute to inhibiting the development of a cancer metastatic phenotype. Finally, DZNeP negatively regulated the TGFß pathway. In conclusion, we propose that inhibition of EZH2 might be considered as a therapeutic strategy against glioblastoma.
Autores: Sáez Castresana, Javier
ISSN 2157-2518  Vol. 6  Nº 6  2015  págs. e119
Autores: Torres-Martín, M.; Lassaletta, L.; De Campos, J.M.; et al.
ISSN 1045-2257  Vol. 54  Nº 4  2015  págs. 197 - 209
Schwannomas are tumors that develop from Schwann cells in the peripheral nerves and commonly arise from the vestibular nerve. Vestibular schwannomas can present unilaterally and sporadically or bilaterally when the tumor is associated with neurofibromatosis Type 2 (NF2) syndrome. The molecular hallmark of the disease is biallelic inactivation of the NF2 gene. The epigenetic signature of schwannomas remains poorly understood and is mostly limited to DNA methylation of the NF2 gene, whose altered expression due to epigenetic factors in this tumor is controversial. In this study, we tested the genomewide DNA methylation pattern of schwannomas to shed light on this epigenetic alteration in these particular tumors. The methodology used includes Infinium Human Methylation 450K BeadChip microarrays in a series of 36 vestibular schwannomas, 4 nonvestibular schwannomas, and 5 healthy nerves. Our results show a trend toward hypomethylation in schwannomas. Furthermore, homeobox (HOX) genes, located at four clusters in the genome, displayed hypomethylation in several CpG sites in the vestibular schwannomas but not in the nonvestibular schwannomas. Several microRNA (miRNA) and protein-coding genes were also found to be hypomethylated at promoter regions and were confirmed as upregulated by expression analysis; including miRNA-21, Met Proto-Oncogene (MET), and PMEPA1. We also detected methylation patterns that might be involved in alternative transcripts of several genes such as NRXN1 or MBP, which would increase the complexity of the methylation and expression patterns. Overall, our results show specific epigenetic signatures in several coding genes and miRNAs that could potentially be used as therapeutic targets.
Autores: Mur, P.; Mollejo, M.; Hernández-Iglesias, T.; et al.
ISSN 0022-3069  Vol. 74  Nº 3  2015  págs. 241 - 249
According to World Health Organization criteria, diffuse gliomas are divided into several histological subtypes, including astrocytomas, oligodendrogliomas, and oligoastrocytomas, and 4 malignancy grades (I-IV). Molecular alterations, such as the isocitrate dehydrogenase gene (IDH) mutation or 1p/19q loss, are found in these tumors but are not included in the current classification system. Recently, mutation of ¿ thalassemia/mental retardation syndrome X-linked (ATRX) gene and its loss of expression have been reported in infiltrating gliomas. We evaluated ATRX protein expression in 272 gliomas and its association with molecular and clinical features. Loss of ATRX expression was more common in tumors with an astrocytic component (astrocytomas II/III, 46.4%; oligoastrocytomas, 47.5%) but was uncommon in oligodendrogliomas (7.3%) and glioblastomas (0.9%). In astrocytic tumors, loss of ATRX expression was significantly associated with longer overall survival. Remarkably, on the basis of IDH mutation, 1p/19q codeletion, and ATRX expression, our study defined 4 molecularly and prognostically different groups of gliomas, showing the relevance of ATRX expression as a new marker for refining the molecular classification of gliomas and for distinguishing clinically distinct prognostic subgroups of patients.
Autores: Shahi, M.H.; Zazpe, I.; Afzal, M.; et al.
ISSN 1010-4283  Vol. 36  Nº 4  2015  págs. 2383 - 2391
Glioma constitutes one of the most common groups of brain tumors, and its prognosis is influenced by different genetic and epigenetic modulations. In this study, we demonstrated low or no expression of hedgehog interacting protein (HHIP) in most of the cell lines and primary glioma tumor samples. We further proceeded to promoter methylation study of this gene in the same cell lines and primary tumor samples and found 87 % (7/8) HHIP methylation in glioblastoma cell lines and 75 % (33/44) in primary tumor samples. These methylation pattern correlates with low or unexpressed HHIP in both cell lines and primary tumor samples. Our results suggest the possibility of epigenetic regulation of this gene in glioma, similarly to medulloblastoma, gastric, hepatic, and pancreatic cancers. Also, HHIP might be a diagnostic or prognostic marker in glioma and help to the detection of these tumors in early stages of disease.
Autores: Torres-Martín, M.; Kusak, M.E.; Isla, A.; et al.
ISSN 2210-7762  Vol. 208  Nº 6  2015  págs. 327 - 332
Meningiomas are common intracranial tumors derived from arachnoid cells. Multiple meningiomas are occasionally present even in patients with no history of neurofibromatosis type 2, a condition that can cause the formation of this neoplasm. Previous studies have shown that most multiple meningiomas are monoclonal in origin. In this study, exome sequencing was performed on four meningiomas and the corresponding peripheral blood DNA from a 61-year-old woman with sporadic multiple meningioma. At least three common mutational events (at the NF2, FAM109B, and TPRXL genes) were detected in the tumors' DNA when they were compared with the lymphocyte DNA from the patient as control. Additionally, an array of unique mutations was detected in each tumor, including in SMARCB1 in two of the samples, a gene whose alteration leads to the development of meningioma. Mutations in other genes, such as IRS4, GULP1, NHSL1, and C10orf53, accounted for one alteration in each meningioma nodule. Our data suggest a monoclonal origin of the meningiomas in this patient, although the numerous alterations contained in each sample indicated multiple secondary variable changes in each tumor nodule. Whether the alterations described in this work are drivers of tumorigenesis or are simply passengers requires further study.
Autores: Ordóñez Ciriza, Raquel; Gallo Oller, Gabriel Osvaldo; Martínez-Soto, S.; et al.
Revista: PLOS ONE
ISSN 1932-6203  Vol. 9  Nº 11  2014  págs. e113105
Neuroblastoma has a very diverse clinical behaviour: from spontaneous regression to a very aggressive malignant progression and resistance to chemotherapy. This heterogeneous clinical behaviour might be due to the existence of Cancer Stem Cells (CSC), a subpopulation within the tumor with stem-like cell properties: a significant proliferation capacity, a unique self-renewal capacity, and therefore, a higher ability to form new tumors. We enriched the CSC-like cell population content of two commercial neuroblastoma cell lines by the use of conditioned cell culture media for neurospheres, and compared genomic gains and losses and genome expression by array-CGH and microarray analysis, respectively (in CSC-like versus standard tumor cells culture). Despite the array-CGH did not show significant differences between standard and CSC-like in both analyzed cell lines, the microarray expression analysis highlighted some of the most relevant biological processes and molecular functions that might be responsible for the CSC-like phenotype. Some signalling pathways detected seem to be involved in self-renewal of normal tissues (Wnt, Notch, Hh and TGF-ß) and contribute to CSC phenotype. We focused on the aberrant activation of TGF-ß and Hh signalling pathways, confirming the inhibition of repressors of TGF-ß pathway, as SMAD6 and SMAD7 by RT-qPCR. The analysis of the Sonic Hedgehog pathway showed overexpression of PTCH1, GLI1 and SMO. We found overexpression of CD133 and CD15 in SIMA neurospheres, confirming that this cell line was particularly enriched in stem-like cells. This work shows a cross-talk among different pathways in neuroblastoma and its importance in CSC-like cells.
Autores: Torres-Martín, M.; Lassaletta, L.; Isla, A.; et al.
ISSN 1021-335X  Vol. 32  Nº 6  2014  págs. 2327 - 2334
Schwannomas and grade I meningiomas are non-metastatic neoplasms that share the common mutation of gene NF2. They usually appear in neurofibromatosis type 2 patients. Currently, there is no drug treatment available for both tumors, thus the use of wide expression technologies is crucial to identify therapeutic targets. Affymetrix Human Gene 1.0 ST was used to test global gene expression in 22 meningiomas, 31 schwannomas and, as non-tumoral controls, 3 healthy meningeal tissues, 8 non-tumoral nerves and 1 primary Schwann cell culture. A non-stringent P-value cut-off and fold change were used to establish deregulated genes. We identified a subset of genes that were upregulated in meningiomas and schwannomas when compared to their respectively healthy tissues, including PDGFD, CDH1 and SLIT2. Thus, these genes should be thoroughly studied as targets in a possible combined treatment.
Autores: Torres-Martín, M.; Peña-Granero, C.; Carceller, F.; et al.
ISSN 1755-8166  Vol. 7  Nº 1  2014 
Background: Pediatric oligodendrogliomas are rare and appear to show a different molecular profile from adult tumors. Some gliomas display allelic losses at 1p/19q in pediatric patients, although less frequently than in adult patients, but this is rare in tumors with an oligodendroglial component. The molecular basis of this genomic abnormality is unknown in pediatric gliomas, but it represents a relatively common finding in pediatric oligodendroglioma-like neoplasms with leptomeningeal dissemination. Results: Multiplex ligation-dependent probe amplification (MLPA) analysis using SALSA P088-B1 for the analysis of the 1p/19q allelic constitution in a pediatric anaplastic (oligodendro) glioma showed homozygous co deletion for markers: TNFRSF4 (located at 1p36.33), TP73 (1p36.32), PPAP2B (1pter-p22.1), DPYD (1p21.3), and PDCD5 (19q13.12), and hemizygous deletion of BAX (19q13.3-q13.4). No sequence changes for R132 and R172 of the IDH1/2 genes were identified. Conclusions: The molecular findings in this pediatric anaplastic glioma do not allow for a clearly definitive pathological diagnosis. However, the findings provide data on a number of 1p/19q genomic regions that, because of homozygotic deletion, might be the location of genes that are important for the development and clinical evolution of some malignant gliomas in children.
Autores: Gallo Oller, Gabriel Osvaldo; Rey, J.A.; Dotor de las Herrerías, Javier; et al.
ISSN 0301-4851  Vol. 41  Nº 10  2014  págs. 6335 - 6341
The determination of cell invasion by matrigel assay is usually evaluated by counting cells able to pass through a porous membrane and attach themselves to the other side, or by an indirect quantification of eluted specific cell staining dye by means of optical density measurement. This paper describes a quantitative analytical imaging approach for determining the invasiveness of tumor cells using a simple method, based on images processing with the public domain software, ImageJ. Images obtained by direct capture are split into the red channel, and the generated image is used to measure the area that cells cover in the picture. To overcome the several disadvantages that classical cell invasion determinations present, we propose this method because it generates more accurate and sensitive determinations, and it could be a reasonable option for improving the quality of the results. The cost-effective alternative method proposed is based on this simple and robust software that is worldwide affordable.
Autores: Gaitán Mantaras, Leandro Martín; Sáez Castresana, Javier
ISSN 1662-5161  Vol. 8  2014  págs. 684
Autores: Ugur, H.C.; Taspinar, M.; Ilgaz, S.; et al.
ISSN 0301-4851  Vol. 41  Nº 2  2014  págs. 697 - 703
The treatment of anaplastic astrocytoma (AA) is controversial. New chemotherapeutic approaches are needed for AA treatment. Temozolomide (TMZ) is one of the chemotherapeutic drugs for the treatment of AA. The cytotoxic effects of TMZ can be removed by the MGMT (O(6)-methylguanine-DNA methyltransferase) enzyme. Then, chemotherapeutic resistance to TMZ occurs. MGMT inhibition by MGMT inactivators (such as lomeguatrib) is an important anticancer therapeutic approach to circumvent TMZ resistance. We aim to investigate the effect of TMZ-lomeguatrib combination on MGMT expression and TMZ sensitivity of SW1783 and GOS-3 AA cell lines. The sensitivity of SW1783 and GOS-3 cell lines to TMZ and to the combination of TMZ and lomeguatrib was determined by a cytotoxicity assay. MGMT methylation was detected by MS-PCR. MGMT and p53 expression were investigated by real-time PCR after drug treatment, and the proportion of apoptotic cells was analyzed by flow cytometry. When the combination of TMZ-lomeguatrib (50 mu M) was used in AA cell lines, IC50 values were reduced compared to only using TMZ. MGMT expression was decreased, p53 expression was increased, and the proportion of apoptotic cells was induced in both cell lines. The lomeguatrib-TMZ combination did not have any effect on the cell cycle and caused apoptosis by increasing p53 expression and decreasing MGMT expression. Our study is a pilot study investigating a new therapeutic approach for AA treatment, but further research is needed.
Autores: Mur, P.; Mollejo, M.; Ruano, Y.; et al.
ISSN 0001-6322  Vol. 126  Nº 2  2013  págs. 277 - 289
Oligodendroglial tumors (OTs) are primary brain tumors that show variable clinical and biological behavior. The 1p/19q codeletion is frequent in these tumors, indicating a better prognosis and/or treatment response. Recently, the prognostically favorable CpG island methylator phenotype (CIMP) in gliomas (G-CIMP+) was associated with mutations in the isocitrate dehydrogenase 1 and isocitrate dehydrogenase 2 (IDH) genes, as opposed to G-CIMP- tumors, highlighting the relevance of epigenetic mechanisms. We performed a whole-genome methylation study in 46 OTs, and a gene expression study of 25 tumors, correlating the methylation and transcriptomic profiles with molecular and clinical variables. Here, we identified two different epigenetic patterns within the previously described main G-CIMP+ profile. Both IDH mutation-associated methylation profiles featured one group of OTs with 1p/19q loss (CD-CIMP+), most of which were pure oligodendrogliomas, and a second group with intact 1p/19q and frequent TP53 mutation (CIMP+), most of which exhibited a mixed histopathology. A third group of OTs lacking the CIMP profile (CIMP-), and with a wild-type IDH and an intact 1p/19q, similar to the G-CIMP- subgroup, was also observed. The three CIMP groups presented a significantly better (CD-CIMP+), intermediate (CIMP+) or worse (CIMP-) prognosis. Furthermore, transcriptomic analyses revealed CIMP-specific gene expression signatures, indicating the impact of genetic status (IDH mutation, 1p/19q codeletion, TP53 mutation) on gene expression, and pointing to candidate biomarkers. Therefore, the CIMP profiles contributed to the identification of subgroups of OTs characterized by different prognoses, histopathologies, molecular features and gene expression signatures, which may help in the classification of OTs.
Autores: Lassaletta, L.; Torres-Martín, M.; San Román-Montero, J.M.; et al.
ISSN 0937-4477  Vol. 270  Nº 9  2013  págs. 2433 - 2438
DNA copy gains are a common event in tumor growth. This study determines the gene dosage/amplification of seven tumor-related genes in patients undergoing vestibular schwannoma (VS) surgery and analyzes its clinical implications. Thirty-three patients undergoing surgery for VS were studied. Seven genes (EGFR, ERBB2, ERBB3, ERBB4, MDM2, MDM4, and NMYC) were analyzed by Quantitative real-time PCR. Copy gains were correlated with demographic, clinical and radiological data. Of the 33 samples, 48 % were positive for copy gains in at least one gene. There were no positive samples for gene amplification. A clinical correlation between tumor size and copy gains of ERBB2 was found. Patients with copy gains of this gene had larger tumors measured by diameter (p = 0.027) and volume (p = 0.005). Copy gains of EGFR, ERBB2, ERBB4, and MDM4 were associated with preoperative tinnitus. Contrary to other tumors of the central nervous system, development of VS does not appear to involve gene amplification. However, copy gains of certain tumor-related genes may play a role in the biological behavior of these neoplasms. Our findings support the role of ERBB2 in VS development and growth.
Autores: Celay Leoz, Ion; Blanco, I.; Lázcoz Ripoll, Paula; et al.
Revista: PLOS ONE
ISSN 1932-6203  Vol. 8  Nº 5  2013  págs. e62771
To determine the effect of retinoic acid (RA) in neuroblastoma we treated RA sensitive neuroblastoma cell lines with 9-cis RA or ATRA for 9 days, or for 5 days followed by absence of RA for another 4 days. Both isomers induced apoptosis and reduced cell density as a result of cell differentiation and/or apoptosis. Flow cytometry revealed that 9-cis RA induced apoptosis more effectively than ATRA. The expression profile of apoptosis and survival pathways was cell line specific and depended on the isomer used.
Autores: Torres-Martín, M.; Martínez-González, V.; Peña-Granero, C.; et al.
ISSN 1699-048X  Vol. 15  Nº 5  2013  págs. 409 - 411
Gene expression array analysis is providing key data on the potential candidate genes and biological pathways involved in schwannoma origin and development. In this way we performed expression array studies on tumor-related genes in schwannomas. The GE Array Q Series HS-006 (SuperArray, Bethesda, MD, USA) was used to determine the expression levels of 96 genes corresponding to 6 primary biological regulatory pathways in a series of 23 schwannomas. We identified 15 genes down-regulated, primarily corresponding to signal transduction functions, and 26 genes up-regulated, most frequently involving cell adhesion functions. In addition to the NF2 inactivation (considered as an early step), variations of other biological regulatory pathways might play a key role in schwannoma.
Autores: Taspinar, M.; Ilgaz, S.; Ozdemir, M.; et al.
ISSN 1010-4283  Vol. 34  Nº 3  2013  págs. 1935 - 1947
Temozolomide (TMZ) is commonly used in the treatment of glioblastoma (GBM). The MGMT repair enzyme (O (6)-methylguanine-DNA methyltransferase) is an important factor causing chemotherapeutic resistance. MGMT prevents the formation of toxic effects of alkyl adducts by removing them from the DNA. Therefore, MGMT inhibition is an interesting therapeutic approach to circumvent TMZ resistance. The aim of the study was to investigate the effect of the combination of lomeguatrib (an MGMT inactivator) with TMZ, on MGMT expression and methylation. Primary cell cultures were obtained from GBM tumor tissues. The sensitivity of primary GBM cell cultures and GBM cell lines to TMZ, and to the combination of TMZ and lomeguatrib, was determined by a cytotoxicity assay (MTT). MGMT and p53 expression, and MGMT methylation were investigated after drug application. In addition, the proportion of apoptotic cells and DNA fragmentation was analyzed. The combination of TMZ and lomeguatrib in primary GBM cell cultures and glioma cell lines decreased MGMT expression, increased p53 expression, and did not change MGMT methylation. Moreover, apoptosis was induced and DNA fragmentation was increased in cells. In addition, we also showed that lomeguatrib-TMZ combination did not have any effect on the cell cycle. Finally, we determined that the sensitivity of each primary GBM cells and glioma cell lines to the lomeguatrib-TMZ combination was different and significantly associated with the structure of MGMT methylation. Our study suggests that lomeguatrib can be used with TMZ for GBM treatment, although further clinical studies will be needed so as to determine the feasibility of this therapeutic approach.
Autores: Torres-Martín, M.; Lassaletta, L.; De Campos, J.M.; et al.
Revista: PLOS ONE
ISSN 1932-6203  Vol. 8  Nº 6  2013  págs. e65868
Background: Vestibular schwannomas are benign tumors that arise from Schwann cells in the VIII cranial pair and usually present NF2 gene mutations and/or loss of heterozygosity on chromosome 22q. Deregulation has also been found in several genes, such as ERBB2 and NRG1. MicroRNAs are non-coding RNAs approximately 21 to 23 nucleotides in length that regulate mRNAs, usually by degradation at the post-transcriptional level. Methods: We used microarray technology to test the deregulation of miRNAs and other non-coding RNAs present in GeneChip miRNA 1.0 (Affymetrix) over 16 vestibular schwannomas and 3 control-nerves, validating 10 of them by qRT-PCR. Findings: Our results showed the deregulation of 174 miRNAs, including miR-10b, miR-206, miR-183 and miR-204, and the upregulation of miR-431, miR-221, miR-21 and miR-720, among others. The results also showed an aberrant expression of other non-coding RNAs. We also found a general upregulation of the miRNA cluster located at chromosome 14q32. Conclusion: Our results suggest that several miRNAs are involved in tumor formation and/or maintenance and that global upregulation of the 14q32 chromosomal site contains miRNAs that may represent a therapeutic target for this neoplasm.
Autores: Torres-Martín, M.; Martínez-González, V.; Peña-Granero, C.; et al.
ISSN 1792-1074  Vol. 6  Nº 1  2013  págs. 275 - 279
Examining aberrant pathway alterations is one method for understanding the abnormal signals that are involved in tumorigenesis and tumor progression. In the present study, expression arrays were performed on tumor-related genes in meningiomas. The GE Array Q Series HS-006 was used to determine the expression levels of 96 genes that corresponded to six primary biological regulatory pathways in a series of 42 meningiomas, including 32 grade I, four recurrent grade I and six grade II tumors, in addition to three normal tissue controls. Results showed that 25 genes that were primarily associated with apoptosis and angiogenesis functions were downregulated and 13 genes frequently involving DNA damage repair functions were upregulated. In addition to the inactivation of the neurofibromin gene, NF2, which is considered to be an early step in tumorigenesis, variations of other biological regulatory pathways may play a significant role in the development of meningioma.
Autores: Torres-Martín, M.; Lassaletta, L.; San Román-Montero, J.; et al.
ISSN 1019-6439  Vol. 42  Nº 3  2013  págs. 848 - 862
Vestibular schwannomas are benign neoplasms that arise from the vestibular nerve. The hallmark of these tumors is the biallelic inactivation of neurofibromin 2 (NF2). Transcriptomic alterations, such as the neuregulin 1 (NRG1)/ErbB2 pathway, have been described in schwannomas. In this study, we performed a whole transcriptome analysis in 31 vestibular schwannomas and 9 control nerves in the Affymetrix Gene 1.0 ST platform, validated by quantitative real-time PCR (qRT-PCR) using Taq Man Low Density arrays. We performed a mutational analysis of NF2 by PCR/denaturing high-performance liquid chromatography (dHPLC) and multiplex ligation-dependent probe amplification (MLPA), as well as a microsatellite marker analysis of the loss of heterozygosity (LOH) of chromosome 22q. The microarray analysis demonstrated that 1,516 genes were deregulated and 48 of the genes were validated by qRT-PCR. At least 2 genetic hits (allelic loss and/or gene mutation) in NF2 were found in 16 tumors, seven cases showed 1 hit and 8 tumors showed no NF2 alteration. MET and associated genes, such as integrin, alpha 4 (ITGA4)/B6, PLEXNB3/SEMA5 and caveolin-1 (CAV1) showed a clear deregulation in vestibular schwannomas. In addition, androgen receptor (AR) downregulation may denote a hormonal effect or cause in this tumor. Furthermore, the osteopontin gene (SPP1), which is involved in merlin protein degradation, was upregulated, which suggests that this mechanism may also exert a pivotal role in schwannoma merlin depletion. Finally, no major differences were observed among tumors of different size, histological type or NF2 status, which suggests that, at the mRNA level, all schwannomas, regardless of their molecular and clinical characteristics, may share common features that can be used in their treatment.
Autores: Lassaletta, L.; Torres-Martín, M.; Peña-Granero, C.; et al.
ISSN 1531-7129  Vol. 34  Nº 7  2013  págs. 1355 - 1361
Hypothesis: NF2 gene alterations may have a clinical impact in non-NF2 vestibular schwannomas (VSs). Background: It has been suggested that NF2 mutations might correlate with clinical expression of VS in NF2 patients. The aim of this study was to analyze the impact of genetic alterations in the NF2 gene on epidemiologic, clinical, and radiologic features of patients with sporadic VS. The association between cigarette consumption and the molecular genetic findings was also studied. Methods: The study group consisted of 51 patients who underwent surgery for removal of vestibular schwannoma in our institution between January 2006 and December 2010. Five highly polymorphic microsatellite DNA markers were used to observe the frequency of loss of heterozygosity (LOH) in chromosome 22. The NF2 gene mutations were detected using polymerase chain reaction amplification and denaturing high-performance liquid chromatography analysis (PCR/dHPLC), and direct sequencing of NF2. Multiplex ligation-dependent probe amplification (MLPA) of the NF2 gene was also performed. Results: An NF2 mutation was identified in 49%, 22q LOH in 57%, and MLPA alterations in 13.7% of the cases. One mutational hit was present in 27%, and 2 hits were present in 45% of the tumors. No association was found between the type of NF2 mutation and relevant clinical parameters. The presence of NF2 mutations detected by PCR/dHPLC was associated with no complaint of hearing loss at the time of diagnosis (p = 0.023), with subjective aural fullness (p = 0.022) and with an absence of tumor involvement of the internal auditory canal (p = 0.029). Patients with NF2 mutations had lower mean corrected PTA thresholds compared with those with no NF2 mutation (p = 0.037). Inactivation of the NF2 gene by mutation, MLPA, or LOH was more frequent in smokers when compared with never smokers (p = 0.048). Conclusion: NF2 mutations may play a role in the pathophysiology of hearing loss as well as in the pattern of growth of VS. Cigarette smoking in patients with VS seems to play a role in both the risk of developing the tumor and also in its genetic profile. More studies are needed to corroborate these results and, more broadly, to establish links between molecular and clinical data.
Autores: García López, Ricardo; Vera-Cano, B.; Vacas-Oleas, A.; et al.
ISSN 0008-5472  Vol. 73  Nº 8 Supl.1  2013  págs. 5053
Autores: Shahi, M.H.; Rey, J.A.; Sáez Castresana, Javier
ISSN 1472-8222  Vol. 16  Nº 12  2012  págs. 1227 - 1238
Introduction: The sonic hedgehog (Shh) pathway is a regulatory network involved in development and cancer. Proteins like Ptch, SMO, and Gli are central to the Shh pathway. Other proteins like HHIP, SUFU, Bmi-1, Cyclin D2, Plakoglobin, PAX6, Nkx2.2, and SFRP1 are not so well understood in Shh regulation as Gli-1 downstream target genes. Areas covered: In this review we try to explain the Shh pathway components and their role in development and cancer, mainly of the brain. A summary of each of the proteins is presented together with an overview of their involvement in cancer. Expert opinion: Genetic alterations of the Shh pathway have been detected in cancer stem cells, a subgroup of tumor cells implicated in the origin and maintenance of tumors, being responsible for cancer recurrence and chemotherapy resistance. Cancer stem cells constitute a novel target for biomedical researchers. Specifically, the Shh pathway is being explored as a new opportunity for targeted therapies against tumors. Therefore, a better knowledge of every of the regulators of the Shh pathway is needed.
Autores: Muñoz, J.; Inda Pérez, María del Mar; Lázcoz Ripoll, Paula; et al.
ISSN 2090-5505  Vol. 2012  2012  págs. 576578
While allelic losses and mutations of tumor suppressor genes implicated in the etiology of astrocytoma have been widely assessed, the role of epigenetics is still a matter of study. We analyzed the frequency of promoter hypermethylation by methylation-specific PCR (MSP) in five tumor suppressor genes (PTEN, MGMT, RASSF1A, p14(ARF), and p16(INK4A)), in astrocytoma samples and cell lines. RASSF1A was the most frequently hypermethylated gene in all grades of astrocytoma samples, in cell lines, and in adult secondary GBM. It was followed by MGMT. PTEN showed a slight methylation signal in only one GBM and one pilocytic astrocytoma, and in two cell lines; while p14(ARF) and p16(INK4A) did not show any evidence of methylation in primary tumors or cell lines. In pediatric GBM, RASSF1A was again the most frequently altered gene, followed by MGMT; PTEN, p14 and p16 showed no alterations. Lack or reduced expression of RASSF1A in cell lines was correlated with the presence of methylation. RASSF1A promoter hypermethylation might be used as a diagnostic marker for secondary GBM and pediatric GBM. Promoter hypermethylation might not be an important inactivation mechanism in other genes like PTEN, p14(ARF) and p16(INK4A), in which other alterations (mutations, homozygous deletions) are prevalent.
Autores: Celis-Aguilar, E.; Lassaletta, L.; Torres-Martín, M.; et al.
ISSN 2090-3154  Vol. 2012  2012  págs. 856157
Hearing loss is the most common symptom in patients with vestibular schwannoma (VS). In the past, compressive mechanisms caused by the tumoral mass and its growth have been regarded as the most likely causes of the hearing loss associated with VS. Interestingly, new evidence proposes molecular mechanisms as an explanation for such hearing loss. Among the molecular mechanisms proposed are methylation of TP73, negative expression of cyclin D1, expression of B7-H1, increased expression of the platelet-derived growth factor A, underexpression of PEX5L, RAD54B, and PSMAL, and overexpression of CEA. Many molecular mechanisms are involved in vestibular schwannoma development; we review some of these mechanisms with special emphasis on hearing loss associated with vestibular schwannoma.
Autores: Enguita Germán, Mónica; Schiapparelli, Paula Valentina; Rey, JA; et al.
ISSN 1010-4283  Vol. 31  Nº 5  2011  págs. 381 - 390
Autores: Hayat Shahi, Mehdi; Afzal, M; Sinha, S; et al.
ISSN 0167-594X  Vol. 103  Nº 2  2011  págs. 287 - 296
Autores: Schiapparelli, Paula Valentina; Hayat Shahi, Mehdi; Enguita Germán, Mónica; et al.
Revista: Cancer Letters
ISSN 0304-3835  Vol. 310  Nº 2  2011  págs. 222 - 231
Autores: Balbuena Delgado, Jana; Pachon, Gisela; Lopez-Torrents, Guillermo; et al.
ISSN 1552-4922  Vol. 79A  Nº 9  2011  págs. 672 - 683
The Sonic Hedgehog (Hh) pathway has been implicated in the maintenance of stem or progenitor cells in many adult tissues. Importantly, abnormal Hh pathway activation is also associated with initiation of neoplasia, but its role in tumor growth is still unclear. Here, we demonstrate that cyclopamine, a plant-derived alkaloid product used to inhibit the Hh signaling pathway, reduces the Side Population (SP) obtained by Hoechst 33342 (Ho342) dye measurements. In addition, cyclopamine is able to modulate, along with oxysterols and other products, the ABCG2 transporter by increasing Ho342 and mitoxantrone uptake. Therefore, if the SP is solely measured as a Ho342 dye extruding fraction, this may be significantly modulated by the inhibition of ABCG2 transport fraction, independently from the action of cyclopamine on the Hh pathway. Our results indicate that ABCG2 may act in the upstream regulation of the Hh signaling pathway to protect the stemness of the SP compartment, giving support to the cancer stem cell hypothesis and suggesting that ABCG2 is not only critical for increased resistance to anticancer agents.
Autores: Enguita Germán, Mónica; Gurrea Rubio, Mikel; Schiapparelli, Paula Valentina; et al.
ISSN 0167-594X  Vol. 103  Nº 2  2011  págs. 247 - 253
Autores: Hayat Shahi, Mehdi; Schiapparelli, Paula Valentina; Afzal, M; et al.
ISSN 1010-4283  Vol. 32  Nº 1  2011  págs. 113 - 127
Autores: Schiapparelli, Paula Valentina; Enguita Germán, Mónica; Balbuena, Jana; et al.
ISSN 1021-335X  Vol. 24  Nº 5  2010  págs. 1355 - 1362
Autores: Arrastia, Maria P.; Sáez Castresana, Javier
ISSN 0973-1040  Vol. 6  2010  págs. 35 - 43
Primary brain tumors, benign and malignant, constitute a great number of very different tumors from the point of view of pathology and neuro-oncology. Astrocytomas are the most frequent ones, with various grades of malignacy, from pilocytic astrocytoma (grade I) to glioblastoma (grade IV), the most malignant brain tumor. The incidence of brain tumors has been increased, and no cure exists for them. The use of mathematics and computer models is useful for hypothesis generation on cancer etiology, evolution and prognosis. In this review we try to analyze some of the different growth models applied from mathematics to the biology of brain tumors, like continuum models, the cellular automaton model and the agent-based model.
Autores: Martínez-Glez, V; Alvarez, L; Franco-Hernández, C; et al.
ISSN 0165-4608  Vol. 196  Nº 1  2010  págs. 1 - 6
Autores: Hayat Shahi, Mehdi; Afzal, M; Sinha, S; et al.
ISSN 1471-2407  Vol. 10  2010  págs. 614
Autores: Hossain, M. M.; Meléndez, B.; Rey, J. A.; et al.
Libro:  Molecular considerations and evolving surgical management issues in the treatment of patients with a brain tumor
2015  págs. 103 - 113
Autores: Pérez-Magán, E. ; Rey, J. A. ; Meléndez, B.; et al.
Libro:  Tumor suppressor genes
2012  págs. 247 - 268
Autores: Inda Pérez, María del Mar; Rey, Juan; Fan, Xing; et al.
Libro:  Tumors of the central nervosu sytem
2011  págs. 3-12
Autores: Martínez-Glez, Víctor; Torres-Martín, Miguel; Sáez Castresana, Javier; et al.
Libro:  Tumors of the Central Nervous System
2011  págs. 217-223
Schwannomas are benign tumors that arise sporadically or associated to the NF2 syndrome. The characteristic alteration in schwannomas is the loss of heterozygosity of 22q (up to 50%), where NF2 gene is located. Inactivating mutations of this gene have been found up to 66% of sporadic schwannomas and 33% of NF2-associated tumors. NF2 nonsense and frameshift mutations, both causing truncated proteins, are associated with more severe phenotypes. Merlin, the product of NF2 gene, belongs to the ERM family of proteins that connect the actin cytoskeleton with plasma membrane. Merlin functions as a tumor suppressor and is involved in cell-cell and cell-matrix interactions through an array of molecular pathways. Merlin over-expression can inhibit both cell proliferation and the transformation induced by oncogenes, and its down-regulation cause a lack in contact inhibition, leading to neoplastic transformation. Another oncogenic mechanism studied in schwannomas is the epigenetic hypermethylation of genic promoters. The study of epigenetic gene silencing in schwannomas has shown high frequencies of promoter hypermethylation in some well known cancer-related genes, and specifically on NF2 gene. There are many unknown aspects in the molecular biology of schwannomas. However, current knowledge and technical advances allows us to be optimistic about future perspectives.
Autores: Franco-Hernandez, Carmen; Torres-Martin, Miguel; Martinez-Glez, Victor; et al.
Libro:  Brain Cancer
2011  págs. 65-69