[Identification of genetic alterations by multiple ligation-dependent probe amplification (MLPA) analysis in oligodendrogliomas]. / Identificación de alteraciones genéticas en oligodendrogliomas mediante amplificación dependiente de ligasa de múltiples sondas (MLPA) (multiple ligation-dependent probe amplification).

Concurrent deletion at 1p/19q is a common signature of oligodendrogliomas, and it may be identified in low-grade tumours (grade II) suggesting it represents an early event in the development of these brain neoplasms. Additional non-random changes primarily involve CDKN2A, PTEN and EGFR. Identification of all of these genetic changes has become an additional parameter in the evaluation of the clinical patients' prognosis, including good response to conventional chemotherapy. Multiple ligation-dependent probe amplification (MLPA) analysis is a new methodology that allows an easy identification of the oligodendrogliomas' abnormalities in a single step. No need of the respective constitutional DNA from each patient is another advantage of this method. We used MLPA kits P088 and P105 to determine the molecular characteristics of a series of 40 oligodendrogliomas. Deletions at l p and 19q were identified in 45% and 65% of cases, respectively. Alterations of EGFR, CDKN2A, ERBB2, PTEN and TP53 were also identified in variable frequencies among 7% to 35% of tumours. These findings demonstrate that MLPA is a reliable technique to the detection of molecular genetic changes in oligodendrogliomas.

Microarray gene expression profiling in meningiomas and schwannomas.

Microarray gene expression profiling is a high throughput system recently used in basic and applied research. It provides a large amount of data -at molecular level- that once acquired, must be functionally integrated in order to find common patterns within a defined group of biological samples. In addition to identification of differentially expressed genes and the establishment of gene regulation patterns, microarrays may also allow us to discover new tumor markers that could have a great impact on the improvement of clinical practice and therapeutics for cancer. The classification method used for cancer is currently based on the morphological characteristics of the biological samples. The information obtained with this method is limited, omitting many important tumor characteristics like the proliferation rate, the capacity of invasion and metastases, as well as the possible development of mechanisms of cellular resistance to treatment. Microarrays can be used in combination with conventional diagnostics as a helpful complement. In this review we focus on how this technology has contributed to our knowledge of the molecular pathogenesis of meningiomas and schwannomas, its potential role as a useful tool for tumor classification and its application in clinical practice.

DAPK1 promoter hypermethylaiton in brain metastases and peripheral blood.

The DAPK1 gene works as a regulator of apoptosis and is frequently inactivated in cancer by aberrant promoter hypermethylation. Loss of DAPK1 expression is associated with a selective advantage for tumor cells to resist apoptotic stimuli, allowing them to separate from the original tumor; from this point of view, DAPK1 could be considered a tumor metastases inhibitor gene. To verify the participation of DAPK1 silencing in cerebral invasion, we analyzed its promoter methylation status in a series of 28 samples from cerebral metastases using MSP and sequencing of the MSP-product. We have found hypermethylation in 53.6% (15/28) metastatic tumor samples as well as in 27.8% (5/18) of its peripheral blood samples. Our data suggest an important role of DAPK1 for silencing through promoter CpG island hypermethylation in the development of brain metastases from solid tumors. The detection of aberrant hypermethylation on DAPK1 promoter from peripheral blood samples has potential clinical implications as a tumor prognosis marker.

[Biology molecular of glioblastomas]. / Biología molecular de los glioblastomas.

Glioblastomas, the most frequent and malignant human brain tumors, may develop de novo (primary glioblastoma) or by progression from low-grade or anapalsic astrocytoma (secondary glioblastoma). The molecular alteration most frequent in these tumor-like types is the loss of heterozygosity on chromosome 10, in which several genes have been identified as tumors suppressor. The TP53/MDM2/P14arf and CDK4/RB1/ P16ink4 genetic pathways involved in cycle control are deregulated in the majority of gliomas as well as genes that promote the cellular division, EGFR. Finally the increase of growth and angiogenics factors is also involved in the development of glioblastomas. One of the objectives of molecular biology in tumors of glial ancestry is to try to find the genetic alterations that allow to approach better the classification of glioblastomas, its evolution prediction and treatment. The new pathmolecular classification of gliomas should improve the old one, especially being concerned about the oncogenesis and heterogeneity of these tumors. It is desirable that this classification had clinical applicability and integrates new molecular findings with some known histological features with pronostic value. In this paper we review the most frequent molecular mechanisms involved in the patogenesis of glioblastomas.

Identificación de alteraciones genéticas en oligodendrogliomas mediante amplificacióndependiente de ligasa de múltiples sondas (MLPA) (multiple ligationdependentprobe amplification) / Identification of genetic alterations by multiple ligation- dependent probe amplification (MLPA) analysis in oligodendrogliomas

La alteración genética más frecuente en oligodendrogliomases la pérdida conjunta de lp/19q. Este eventoya acontece en etapas primarias del desarrollo deestos tumores. Es de gran valor clínico conocersi dichos tumores poseen esta deleción ya que seha correlacionado con un mejor pronóstico de lospacientes. Además de esta alteración. también se haobservado la deleción de CDKN2A y PTEN y la amplificaciónde EGFR; estos cambios parecen asociarse auna mayor agresividad tumoral. Mediante la técnicade MLPA en una misma reacción podemos determinarsi existe pérdida de lp/19q y deleciones/amplificacionesde los genes anteriormente mencionados en el ADNprocedente de muestras tumorales. En este trabajohemos analizado 40 oligodendrogliomas y el kit MLPAP088 para determinar el estado alélico de lp/19q, asícomo el kit MLPA P105 para observar la amplificación/deleción de los genes CDKN2A, PTEN, ERBB2, TP53 yEGFR. Mostraron pérdida de 1p el 45% de los tumores(18/40) y el 65% (26/40) de los oligodendrogliomaspresentaron deleción de las sondas que hibridan en lasregiones de 19q. Para el kit MLPA P105, mostraronduplicación/deleción de EGFR en el 7,5% (3/41) y 35%(14/40) de las muestras, respectivamente. El 60% de loscasos (24/40) mostraron deleción de CDKN2 y ningunamuestra presentó duplicación de las sondas para estegen. El gen ERBB2 se presentó duplicado en el 12,5%de los tumores (5/40) y un único tumor mostró pérdidasde dicho gen. El 30% (12/40) de las muestras presentódeleción para PTEN y el 12,5% (5/40) mostró duplicaciónde dicho gen y, por último, 12,5% de los casos(5/40) presentaron duplicaciones de TP53. Estos resultadosindican que la técnica de MLPA es idónea para laidentificación de las alteraciones moleculares característicasde oligodendrogliomas. Estas alteraciones estaríancontribuyendo a la formación del tumor, siendola anomalía más significativa en oligodendrogliomas la (...) (AU)

Concurrent deletion at 1p/19q is a common signatureof oligodendrogliomas, and it may be identified inlow-grade tumours (grade II) suggesting it representsan early event in the development of these brain neoplasms.Additional non-random changes primarilyinvolve CDKN2A, PTEN and EGFR. Identification ofall of these genetic changes has become an additionalparameter in the evaluation of the clinical patients' prognosis, including good response to conventional chemotherapy.Multiple ligation-dependent probe amplification(MLPA) analysis is a new methodology thatallows an easy identification of the oligodendrogliomas'abnormalities in a single step. No need of the respectiveconstitutional DNA from each patient is anotheradvantage of this method. We used MLPA kits P088and P105 to determine the molecular characteristics ofa series of 40 oligodendrogliomas. Deletions at l p and19q were identified in 45% and 65% of cases, respectively.Alterations of EGFR, CDKN2A, ERBB2, PTENand TP53 were also identified in variable frequenciesamong 7% to 35% of tumours. These findings demonstratethat MLPA is a reliable technique to the detectionof molecular genetic changes in oligodendrogliomas (AU)

Biología molecular de los glioblastomas / Biology molecular of glioblastomas

La formación de los glioblastomas es muy diversa, pudiendo presentarse de “novo” o provenir de recidivas de astrocitomas que van progresando hacia mayores grados de malignidad. La alteración molecular más frecuente que se encuentra en estos tipos tumorales es la pérdida de heterocigocidad del cromosoma 10en el que se han identificado varios genes supresores de tumores. Las vías genéticas TP53/MDM2/ P14arf yCDK4/RB1/P16ink4 implicadas en división celular, se encuentran desreguladas en la mayoría de los gliomas así como los genes que promueven la división celular, entre ellos EGFR. Por último el aumento de factores decrecimiento y angiogénicos también está involucrado en el desarrollo de estos tipos tumorales. Uno de los objetivos de la biología molecular en tumores de estirpeglial es intentar encontrar marcadores o alteraciones genéticas que permitan abordar mejor la clasificación de los glioblastomas, su evolución y pronóstico así como su tratamiento. La diversidad y la cantidad de las alteraciones moleculares presentes en glioblastomas probablemente sea el motivo por el que todavía no se han encontrado fármacos efectivos para combatirlos. En la actualidad, con la aparición de nuevas técnicas de biología molecular, se puede intentar individualizar y clasificara los pacientes en función de su expresión génica. Esto abre una ventana esperanzadora a la aparición de nuevos fármacos que tengan como diana exclusiva a los genes y/o proteínas alterados de las células tumorales en función de su patrón de expresión génica individualizado para cada tumor. En este artículo revisamos los mecanismos moleculares más frecuentes en la patogénesis de los glioblastomas

Glioblastomas, the most frequent and malignant human brain tumors, may develop de novo (primaryglioblastoma) or by progression from low-grade or anapalsic astrocytoma (secondary glioblastoma). The molecular alteration most frequent in these tumor like types is the loss of heterozygosity on chromosome 10,in wich several genes have been identified as tumors suppressor. The TP53/MDM2/P14arf and CDK4/RB1/P16ink4 genetic pathways involved in cycle control are deregulated in the majority of gliomas as well as genes that promote the cellular division, EGFR. Finally the increase of growth and angiogenics factors is also involved in the development of glioblastomas. One of the objetives of molecular biology in tumors of glial an cestryis to try to find the genetic alterations that allow to approach better the classification of glioblastomas, its evolution prediction and treatment. The new path molecular classification of gliomas should improve the old one, especially being concerned about the oncogenesis and heterogenity of these tumors. It is desirable that this classification had clinical applicability and integrates new molecular findings with some known histological features with prognostic value. In this paper we review the most frequent molecular mechanisms involved in the patogenesis of glioblastomas

Expresión de Oncogenes y Oncosupresores en Meningiomas / Oncogenes and Tumor Suppressor Genes Expression

Los meningiomas son tumores compuestos por células neoplásicas de la capa aracnoide y constituyen aproximadamente el 20% de todos los tumores intracraneales primarios. Hemos estudiado en una serie de meningiomas los niveles de expresión de 96 genes asociados con vías biológicas específicas relacionadas con cáncer. Para ello hemos usado membranas de microarray de expresión validadas por PCR cuantitativa. El estudio se completó con la búsqueda de la pérdida del gen NF2, principal candidato en la génesis de meningiomas, por medio de una amplificación múltipledependiente de ligasa (MLPA). El 78% de las muestras presentó deleción de un alelo del gen NF2. No se encontró ninguna relación significativa entre genes específicos y la pérdida de NF2 encontradas por MLPA. El análisis de expresión por microarray identificó 4 genes con expresión significativamente menor (BAD, BAX, FOS y TNFRSF25) y uno con expresión significativamente mayor (ITGAV) en las muestras de meningioma comparado con las correspondientes expresiones en los controles de meninge no tumoral. La expresión incrementada del gen ITGAV ha sido ya descrita en meningiomas. Por otro lado, la expresión significativamente menor de los genes BAD, BAX, FOS y TNFRSF25, es descrita en este trabajo por primera vez para este tipo tumoral. Estudios específicos para cada gen o sus interacciones aportarán mayor conocimiento sobre los procesos de transformación neoplásica y progresión tumoral en meningiomas

Meningiomas are tumors arising from aracnoid layer cellsand make up 20% of all intracranial tumours. We havestudied in a series of meningiomas the expression levelsof 96 genes associated with specific biological cancer related pathways. We have used expression microarrays validated by quantitative PCR. The study was completed with the search for losses in the NF2 gene, main candidate in the genesis of meningiomas, using multiplex ligase-dependent polymerase amplification (MLPA). 78% of the samples showed deletion for one copy of the NF2 gene. We have not found significant relation between specific genes and the loss of NF2 found by MLPA. The expression analysis by microarray identified 4 genes with significant decreased expression (BAD, BAX, FOS and TNFRSF25) and one with significant increased expression (ITGAV) in the samples of meningioma compared with the corresponding expressions in the controls from non-tumoral cerebral meninges. Increased expression of ITGAV gene has been already described in meningiomas. On the other hand, the significant decreased expression of BAD, BAX, FOS and TNFRSF25 is described in this work for the first time in meningiomas. Specific studies for each gene or its interactions will contribute to a better understanding on the processes of neoplastic transformation and progression in meningiomas