Impacto del miRNA-200c sobre el mecanismo de migración celular en el glioblastoma.Relación con los patrones de amplificación de EGFR.

El Glioblastoma Multiforme (GB), la neoplasia primaria del SNC más importante en adultos, por su frecuencia y agresividad, se muestra como paradigmática de los procesos de infiltración y angiogénesis en las neoplasias. Su localización en el sistema nerviosos central, su alta capacidad invasiva y las consecuencias de una angiogénesis displasica hacen del GB una enfermedad neoplásicas altamente invalidante y de evolución fatal, en la que las distintas acciones terapéuticas se muestran ineficaces. Este trabajo realiza un estudio clínico, morfológico ,genético y epigenético de 46 casos de GB primarios. Se describe un grupo de miRNAs no descritos anteriormente en el GB. Se estableció la correlación entre la expresión de miRNA-200 (down-regulated) y el status de amplificación de EGFR. Este miRNA, podría estar implicado en la modulación de procesos como la movilidad celular y la capacidad de migración e infiltración neoplásica. El objetivo de este estudio es el análisis in vitro de la modulación por miR-200c de “EGFR-vía de señalización – infiltración/cambios fenotípicos EMT”, generando un modelo experimental de transfección en cultivos primarios y líneas celulares de GBMs. Presentamos en este trabajo un estudio in vitro del miR-200c en el GBM primario, su capacidad de modular: la capacidad infiltrativa en esta neoplasia a través de cambios en el perfil “Mesenchymal Mode of Migration and Invasion” (MMMI) de las células neoplásicas. Analizamos para ello la acción de este miRNA, silenciando EGFR y modificando su expresión en condiciones experimentales en seis cultivos primarios y dos líneas celulares establecidas. En el estudio señalamos una fuerte relación entre miRNA-200c y el perfil molecular asociado a su capacidad infiltrativa (MMMI) a través de ZEB-1, ZEB-2 y CDH1. Definir la acción moduladora del miR-200c en este estudio permitirá una posible utilización diagnostica, pronóstica y aplicación terapéutica

The Status of EGFR Modulates the Effect of miRNA-200c on ZEB1 Expression and Cell Migration in Glioblastoma Cells

Migration of glioblastoma cells into surrounding tissue is one of the main features that makes this tumor incurable. We evaluated whole-genome miRNA expression profiling associated with different EGFR amplification patterns in 30 cases of primary glioblastoma. From the 64 miRNAs that showed differential expression between tumors with a high level of EGFR amplification and tumors without EGFR amplification, 40% were related with cell migration, being miR-200c the most differentially expressed between these two groups. We investigated the effect of miR-200c on ZEB1 expression and cell migration in an in vitro transfection model with a miR-200c mimic, a miR-200c inhibitor and siRNA targeting EGFR in three short-term cultures with different levels of EGFR amplification obtained from resected glioblastomas. The cell culture with the highest EGFR amplification level presented the lowest miR-200c expression and the status of EGFR modulated the effect of miR-200c on ZEB1 expression. Silencing EGFR led to miR-200c upregulation and ZEB1 downregulation in transfected cultures, except in the presence of high levels of EGFR. Likewise, miR-200c upregulation decreased ZEB1 expression and inhibited cell migration, especially when EGFR was not amplified. Our results suggest that modulating miR-200c may serve as a novel therapeutic approach for glioblastoma depending on EGFR status

Identification of New Genetic Clusters in Glioblastoma Multiforme: EGFR Status and ADD3 Losses Influence Prognosis

Glioblastoma multiforme (GB) is one of the most aggressive tumors. Despite continuous efforts to improve its clinical management, there is still no strategy to avoid a rapid and fatal outcome. EGFR amplification is the most characteristic alteration of these tumors. Although effective therapy against it has not yet been found in GB, it may be central to classifying patients. We investigated somatic-copy number alterations (SCNA) by multiplex ligation-dependent probe amplification in a series of 137 GB, together with the detection of EGFRvIII and FISH analysis for EGFR amplification. Publicly available data from 604 patients were used as a validation cohort. We found statistical associations between EGFR amplification and/or EGFRvIII, and SCNA in CDKN2A, MSH6, MTAP and ADD3. Interestingly, we found that both EGFRvIII and losses on ADD3 were independent markers of bad prognosis (p = 0.028 and 0.014, respectively). Finally, we got an unsupervised hierarchical classification that differentiated three clusters of patients based on their genetic alterations. It offered a landscape of EGFR co-alterations that may improve the comprehension of the mechanisms underlying GB aggressiveness. Our findings can help in defining different genetic profiles, which is necessary to develop new and different approaches in the management of our patients

Correlation between EGFR amplification and the expression of microRNA-200c in primary glioblastoma multiforme.

Extensive infiltration of the surrounding healthy brain tissue is a critical feature in glioblastoma. Several miRNAs have been related to gliomagenesis, some of them related with the EGFR pathway. We have evaluated whole-genome miRNA expression profiling associated with different EGFR amplification patterns, studied by fluorescence in situ hybridization in tissue microarrays, of 30 cases of primary glioblastoma multiforme, whose clinicopathological and immunohistochemical features have also been analyzed. MicroRNA-200c showed a very significant difference between tumors having or not EGFR amplification. This microRNA plays an important role in epithelial-mesenchymal transition, but its implication in the behavior of glioblastoma is largely unknown. With respect to EGFR status our cases were categorized into three groups: high level EGFR amplification, low level EGFR amplification, and no EGFR amplification. Our results showed that microRNA-200c and E-cadherin expression are down-regulated, while ZEB1 is up-regulated, when tumors showed a high level of EGFR amplification. Conversely, ZEB1 mRNA expression levels were significantly lower in the group of tumors without EGFR amplification. Tumors with a low level of EGFR amplification showed ZEB1 expression levels comparable to those detected in the group with a high level of amplification. In this study we provide what is to our knowledge the first report of association between microRNA-200c and EGFR amplification in glioblastomas

Pam3CSK4, a TLR2 ligand, induces differentiation of glioblastoma stem cells and confers susceptibility to temozolomide

Glioblastoma multiforme (GBM) is the most aggressive human brain tumor, and GBM stem cells (GSC) may be responsible for its recurrence and therapeutic resistance. Toll-like receptors (TLRs), which recognize multiple ligands (endogenous and pathogen-associated) and trigger the immune response of mature immune cells, are also expressed by hematopoietic stem and progenitor cells, where their activation results in the differentiation of these cells into myeloid cells. Since TLR expression has been recently described in neural cells, including neural stem cells, we studied TLR expression by GSCs and the effect of stimulation by TLR ligands on promoting GSC differentiation into mature GBM cells. First, our results showed heterogeneous TLR expression by GBM cells from human tumors and, for the first time, by human GSCs defined by their CD133+ and CD44+ phenotypes. Next, the effect of TLR ligands was studied in in vitro cell cultures of neurospheres and CD44+ cells obtained from two GBM cell lines (U-87 and U-118). The expression of GSC markers diminished in the presence of Pam3CSK4 or LPS (TLR2 and TLR4 ligands, respectively), thus indicating TLR-dependent differentiation. Interestingly, simultaneous treatment with Pam3CSK4 plus temozolomide (TMZ), the reference drug in GBM treatment, significantly increased cell death compared to the effect of the ligand alone, which showed no toxicity, or TMZ alone. These results suggest a synergistic effect between Pam3CSK4 and TMZ based on the induction of TLR-dependent GSC differentiation towards mature GBM cells, which exhibited increased sensitivity to chemotherapy, and provide new perspectives in GBM therapy

Real-Time RT-PCR analysis of EGFR, mir-200c, CDH1 and ZEB1 expression.

<p>Results are representative of 30 different samples. Changes in mRNA expression are reported as mean and standard error with respect to non-amplified <i>EGFR</i> group using the 2^−ΔΔCt method. Statistically significant expression changes (p<0.05) are marked with an *. <b>A.</b> EGFR mRNA expression in the GBM groups with different levels of <i>EGFR</i> amplification. The results were normalized to the actin housekeeping gene. <b>B.</b> miR-200c expression in tumor biopsies from the three studied groups. The results were normalized to the U66 housekeeping gene for miR-200c. <b>C.</b> CDH1 mRNA expression and <b>D</b>. ZEB1 mRNA expression in biopsies from the three studied groups. The results were normalized to the actin housekeeping gene.</p

Microarray analysis of miRNA expression in 30 GBMs.

<p><b>A.</b> Unsupervised hierarchical clustering of GBMs (horizontal dimension) and 102 miRNAs (vertical dimension) derived from a variance analysis. Over-expressed genes are represented in red and under-expressed ones in blue. <b>B.</b> The projection to latent structures discriminant analysis (PLS-DA) score scatter plot of the first 2 components. This PLSDA analysis discriminates the differences between GBM with high-level of <i>EGFR</i> amplification (n = 13) versus GBM non-amplified <i>EGFR</i> (n = 10). The symbols correspond as follows: red triangle, GMB with high level of amplified <i>EGFR</i> samples; blue square, non-amplified <i>EGFR</i> samples; green circle, samples with a low level of <i>EFGR</i> amplification.</p