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Pancreatic cancer_Affymetrix 100K SNP arrays

ABSTRACT: To identify genomic abnormalities characteristic of pancreatic ductal adenocarcinoma (PDAC) in vivo, a panel of 27 microdissected PDAC specimens were analyzed using high-density microarrays representing ~116 000 single nucleotide polymorphism (SNP) loci. We detected frequent gains of 1q, 2, 3, 5, 7p, 8q, 11, 14q and 17q (>78% of cases), and losses of 1p, 3p, 6, 9p, 13q, 14q, 17p and 18q (>44%). Although the results were comparable with those from array CGH, regions of those genetic changes were defined more accurately by SNP arrays. Integrating the Ensembl public data, we have generated "gene" copy number indices that facilitate the search for novel candidates involved in pancreatic carcinogenesis. Copy numbers in a subset of the genes were validated using quantitative real-time PCR. The SKAP2/SCAP2 gene (7p15.2), which belongs to the src family kinases, was most frequently (63%) amplified in our sample set and its recurrent over-expression (67%) was confirmed by reverse transcription-PCR. Furthermore, fluorescence in situ hybridization and in situ RNA hybridization analyses for this gene have demonstrated a significant correlation between DNA copy number and mRNA expression level in an independent sample set (p<0.001). These findings indicate that the dysregulation of SKAP2/SCAP2, which is mostly caused by its increased gene copy number, is likely to be associated with the development of PDAC. Keywords: pancreatic cancer; tissue microdissection; SNP array; DNA copy number; LOH

ORGANISM(S): Homo sapiens

PROVIDER: GSE7130 | GEO | 2007/10/22

SECONDARY ACCESSION(S): PRJNA98215

REPOSITORIES: GEO

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Project description:To identify genomic abnormalities characteristic of pancreatic ductal adenocarcinoma (PDAC) in vivo, a panel of 27 microdissected PDAC specimens were analyzed using high-density microarrays representing ~116 000 single nucleotide polymorphism (SNP) loci. We detected frequent gains of 1q, 2, 3, 5, 7p, 8q, 11, 14q and 17q (>78% of cases), and losses of 1p, 3p, 6, 9p, 13q, 14q, 17p and 18q (>44%). Although the results were comparable with those from array CGH, regions of those genetic changes were defined more accurately by SNP arrays. Integrating the Ensembl public data, we have generated "gene" copy number indices that facilitate the search for novel candidates involved in pancreatic carcinogenesis. Copy numbers in a subset of the genes were validated using quantitative real-time PCR. The SKAP2/SCAP2 gene (7p15.2), which belongs to the src family kinases, was most frequently (63%) amplified in our sample set and its recurrent over-expression (67%) was confirmed by reverse transcription-PCR. Furthermore, fluorescence in situ hybridization and in situ RNA hybridization analyses for this gene have demonstrated a significant correlation between DNA copy number and mRNA expression level in an independent sample set (p<0.001). These findings indicate that the dysregulation of SKAP2/SCAP2, which is mostly caused by its increased gene copy number, is likely to be associated with the development of PDAC. Experiment Overall Design: A total of 27 fresh-frozen PDAC tissue specimens were obtained surgically or at autopsy from Yamaguchi University School of Medicine, Japan. All the tissues were confirmed histologically by a pathologist. Tissue microdissection was manually performed to collect more than 90% of tumor cells in all cases and DNA was extracted using a DNA extraction kit (SepaGene). Reference DNA was obtained from lymphocytes of total 13 healthy volunteers (six males and seven females). To assess DNA copy number alterations and LOH, we used the Copy Number Analyzer for Affymetrix GeneChipÂ® (CNAG, Ver2.0) software (Nannya et al. Cancer Res. 2005 Jul 15;65(14):6071-9). Experiment Overall Design: The following Samples were added to the Series after this study was published: PC5_Hind (GSM278031), PC5_Xba (GSM278032), PC11-Hind (GSM278043), and PC19_Hind (GSM278057). A supplementary file describing the clinical data of 28 microdissected PDAC samples is linked at the bottom of the Series.

Project description:BACKGROUND: Cervical carcinoma develops as a result of multiple genetic alterations. Different studies investigated genomic alterations in cervical cancer mainly by means of metaphase comparative genomic hybridization (mCGH) and microsatellite marker analysis for the detection of loss of heterozygosity (LOH). Currently, high throughput methods such as array comparative genomic hybridization (array CGH), single nucleotide polymorphism array (SNP array) and gene expression arrays are available to study genome-wide alterations. Integration of these 3 platforms allows detection of genomic alterations at high resolution and investigation of an association between copy number changes and expression. RESULTS: Genome-wide copy number and genotype analysis of 10 cervical cancer cell lines by array CGH and SNP array showed highly complex large-scale alterations. A comparison between array CGH and SNP array revealed that the overall concordance in detection of the same areas with copy number alterations (CNA) was above 90%. The use of SNP arrays demonstrated that about 75% of LOH events would not have been found by methods which screen for copy number changes, such as array CGH, since these were LOH events without CNA. Regions frequently targeted by CNA, as determined by array CGH, such as amplification of 5p and 20q, and loss of 8p were confirmed by fluorescent in situ hybridization (FISH). Genome-wide, we did not find a correlation between copy-number and gene expression. At chromosome arm 5p however, 22% of the genes were significantly upregulated in cell lines with amplifications as compared to cell lines without amplifications, as measured by gene expression arrays. For 3 genes, SKP2, ANKH and TRIO, expression differences were confirmed by quantitative real-time PCR (qRT-PCR). CONCLUSION: This study showed that copy number data retrieved from either array CGH or SNP array are comparable and that the integration of genome-wide LOH, copy number and gene expression is useful for the identification of gene specific targets that could be relevant for the development and progression in cervical cancer. Keywords: DNA copynumber RNA expression correlation

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Pancreatic cancer_Affymetrix 100K SNP arrays

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