Gene expression profile of an adenomyoepithelioma of the breast with a reciprocal ranslocation involving chromosomes 8 and 16.
Department of Pathology, Creighton University School of Medicine, 601 North 30th Street, Omaha, NE 68131-2197. Cancer Genetics and Cytogenetics
(Impact Factor: 1.93).
02/2005; 156(1):14-22. DOI: 10.1016/j.cancergencyto.2004.04.024
Myoepithelium is an integral part of the mammary ductal and lobular architecture, positioned between luminal cells and the basement membrane. We describe the first report on cytogenetic findings in an adenomyoepithelioma of the breast with a balanced t(8;16)(p23;q21), and provide gene expression profile using Affymetrix GeneChip U95AV2 (Affymetrix, Santa Clara, CA). Differential analysis identified 857 genes with 2-fold or more mRNA change in comparison to pooled normal breast control; immunohistochemical analysis was used to confirm these results in a limited number of genes. Expression results were grouped based on the chromosomal location of the genes and associated protein function, and identified several potential pathogenetic mechanisms (autocrine and paracrine growth stimuli) in the development of myoepithelial tumors.
Available from: Jaroslav P Novak
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ABSTRACT: DNA microarrays are a powerful technology that can provide a wealth of gene expression data for disease studies, drug development, and a wide scope of other investigations. Because of the large volume and inherent variability of DNA microarray data, many new statistical methods have been developed for evaluating the significance of the observed differences in gene expression. However, until now little attention has been given to the characterization of dispersion of DNA microarray data.
Here we examine the expression data obtained from 682 Affymetrix GeneChips with 22 different types and we demonstrate that the Gaussian (normal) frequency distribution is characteristic for the variability of gene expression values. However, typically 5 to 15% of the samples deviate from normality. Furthermore, it is shown that the frequency distributions of the difference of expression in subsets of ordered, consecutive pairs of genes (consecutive samples) in pair-wise comparisons of replicate experiments are also normal. We describe a consecutive sampling method, which is employed to calculate the characteristic function approximating standard deviation and show that the standard deviation derived from the consecutive samples is equivalent to the standard deviation obtained from individual genes. Finally, we determine the boundaries of probability intervals and demonstrate that the coefficients defining the intervals are independent of sample characteristics, variability of data, laboratory conditions and type of chips. These coefficients are very closely correlated with Student's t-distribution.
In this study we ascertained that the non-systematic variations possess Gaussian distribution, determined the probability intervals and demonstrated that the K(alpha) coefficients defining these intervals are invariant; these coefficients offer a convenient universal measure of dispersion of data. The fact that the K(alpha) distributions are so close to t-distribution and independent of conditions and type of arrays suggests that the quantitative data provided by Affymetrix technology give "true" representation of physical processes, involved in measurement of RNA abundance.
This article was reviewed by Yoav Gilad (nominated by Doron Lancet), Sach Mukherjee (nominated by Sandrine Dudoit) and Amir Niknejad and Shmuel Friedland (nominated by Neil Smalheiser).
Available from: Kennichi Kakudo
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ABSTRACT: Adenomyoepithelioma (AME) of the breast is an uncommon tumor characterized by biphasic proliferation of both epithelial and myoepithelial cells. In rare instances, the epithelial, the myoepithelial or both components of an AME may become malignant. Described herein is the case of a 69-year-old woman who presented with myoepithelial carcinoma of the breast in an AME. Malignancy of myoepithelial component (MEC) was evidenced by the presence of cytological atypia, high mitotic rate, necrosis and local invasion. Immunohistochemical study demonstrated strong expression of P53 and phosphorylated extracellular signal-regulated kinase 1/2 in MEC. Laser capture microdissection technique and mutational analysis further revealed point mutation of the p53 gene (T-->G transversion at codon 270) in this population, but not in glandular epithelial cells or adjacent normal ductal epithelium. No mutations in exons 1 and 2 of the K-, H-, and N-ras genes were identified in any of the neoplastic component. To the authors' knowledge this is the first report of a mutation in the p53 gene in a malignant AME of the breast.
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ABSTRACT: Cytogenetic and molecular studies have shown that approximately 80% of cases of alveolar rhabdomyosarcoma (ARMS) have consistent chromosomal translocation of either t(2;13) or t(1;13), resulting in either PAX3-FKHR or PAX7-FKHR gene fusions. However, 20% of the cases diagnosed histologically are negative for these fusion genes. The clinical and pathological properties of the so-called fusion gene negative tumors remain to be defined. We present an unusual case of a 7-year-old boy who developed three separate primary ARMS over a 5-year period, with the first tumor diagnosed at the age of 12 months. The tumors were negative for the characteristic translocations, t(2;13) or t(1;13), but showed evidence of low-level chromosomal instability and a reciprocal chromosomal translocation t(6;11)(q27;q13). PCR amplification of the p53 gene, exons 2-11, followed by DNA sequencing did not detect any germline p53 mutation. These clinical and cytogenetic features have not been reported previously in ARMS. The findings suggest that cytogenetic abnormalities of chromosome 6 may be associated with the development of early onset multiple ARMS in a subgroup of pediatric patients as seen in this case.
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