p16INK4A (CDKN2A) gene deletion is a frequent genetic event in synovial sarcomas.

We assessed the frequency of genomic deletion of p16 INK4A (CDKN2A) in synovial sarcomas (SSs) and its possible association with immunoexpression of p16 and cyclin D1 and the Ki-67 proliferation index using dualcolor fluorescence in situ hybridization (FISH) on tissue microarray sections of 41 histologically and molecularly confirmed SSs. A heterozygous p16 INK4A gene deletion was identified in 28 (74%) of 38 cases, with 25 (89%) of them showing abnormal p16 protein expression (20 negative and 5 heterogeneous). Of 25 cases, 19 (76%) exhibiting increased cyclin D1 expression also demonstrated heterozygous p16 INK4A deletion. No significant association was observed between p16 INK4A deletion …

Fluorescence In Situ Hybridization (FISH) on Formalin-Fixed Paraffin-Embedded (FFPE) Tissue Sections

Fluorescence In Situ Hybridization (FISH) is a powerful technique for localizing specific DNA targets directly in the fixed tissue or cells. Bacterial artificial chromosome (BAC) as well as commercial probes, which could be supplied ready for use or concentrated and must be diluted following the manufacturers instructions, can be used. The technique requires 2 days, as an overnight incubation of the FISH probes is needed for optimal hybridization. The critical steps include deparaffinization of tissue sections, optimal pretreatment (target retrieval and protein digestion), and probe hybridization. In this chapter, the described FISH protocol provides a methodology for analyzing the cytogene…

Expresión inmunohistoquímica de la proteína mycN y el estado del gen MYCN en tumores neuroblásticos

Antecedentes: Los tumores neuroblásticos son de los tumores pediátricos más frecuentes. A pesar de su gran variedad genética, clínica e histopatológica, la amplificación del gen MYCN es siempre un indicador de mal pronóstico. Este oncogen codifica una proteína nuclear que se une al ADN y activa la transcripción de sus genes diana. Un aumento en el número de copias del gen no se corresponde siempre con sobreexpresión de su proteína. El valor pronóstico de la detección de la proteína es controvertido. Métodos: Se han analizado 220 muestras de NB. Mediante la técnica de FISH se ha establecido el estado del gen, mientras que la inmunohistoquímica ha permitido el estudio de la expresión de la pr…

A Comprehensive Tissue Microarray-Based FISH Screen of ALK Gene in Neuroblastomas

The heterogeneity of neuroblastic tumors added to the immense biological complexity has led to an unprecedented scale of investigations and a growing list of molecular genetic targets for prognosis as well as therapy. Recently, Anaplastic Lymphoma Kinase (ALK) has been identified as a major predisposing gene as well as a potential therapeutic target for neuroblastoma. Individuals with ALK-related neuroblastoma susceptibility (i.e., heterozygous for an ALK mutation) are at risk of developing neuroblastic tumors. Aberrant copy number or mutations in ALK gene and overexpression of its protein tyrosine-kinase receptor have been related to poor prognosis of this disease, although a great degree …

Evaluation of genetic stability of the SYT gene rearrangement by break-apart FISH in primary and xenotransplanted synovial sarcomas

Synovial sarcomas (SS) are infrequent and morphologically heterogeneous soft tissue sarcomas. The t(X;18)(p11.2;q11.2), which results in fusion of the SYT gene at 18q11 with the SSX1, SSX2, or (rarely) SSX4 gene is a primary genetic event in 90% of SS. To determine whether the t(X;18) present in the original tumor is maintained in its passages, a dual-color break-apart FISH assay for SYT gene disruption was performed in two tissue microarrays (TMA) comprising eight molecularly confirmed primary SSs and their xenografts, which were followed for several generations. A simplified scoring system was applied to the FISH results of the primary and xenotransplanted SS to classify the FISH data int…

Aberrant copy numbers of ALK gene is a frequent genetic alteration in neuroblastomas.

A total of 50 neuroblastomas were assessed for frequency of ALK gene copy number aberrations by interphase fluorescence in situ hybridization using a break-apart fluorescence in situ hybridization probe. The data were compared with status of MYCN, 11q, 17q, and 1p36. We observed ALK aberrations (amplification, 1 of 45; gain, 15 of 45 and loss/imbalance, 11 of 45) in a total of 27 (60%) of 45 neuroblastomas. Synchronic MYCN and ALK aberrations accounted for 23 of 45 (51%) tumors; however, MYCN alterations were also detected in 11 (60%) of 18 tumors without ALK aberrations. Our data suggest that copy number aberrations of the ALK gene is a frequent genetic event in the development of neurobla…

Mutational analysis of E-cadherin, β-catenin and APC genes in synovial sarcomas

Immunohistochemical study of correlation between histologic subtype and expression of epithelial-mesenchymal transition-related proteins in synovial sarcomas.

Context.—Synovial sarcomas are mesenchymal tumors with epithelial nature and comprise biphasic and monophasic fibrous subtypes. However, factors determining epithelial or spindle cell differentiation are still unexplored. Aberrant epithelial-mesenchymal transition has been implicated in the pathogenesis of diverse human malignancies.Objective.—To analyze the correlation between cellular phenotype and expression of proteins associated with different epithelial-mesenchymal transition-related pathways.Design.—Immunohistochemical analysis of E-cadherin, Snail, Slug, and dysadherin, components of the Wnt/wingless and PI3K/Akt pathways, was performed on 14 biphasic and 27 monophasic fibrous tumor…