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High-resolution genomic and expression profiling reveals 105 putative amplification target genes in pancreatic cancer.

ABSTRACT: Comparative genomic hybridization (CGH) studies have provided a wealth of information on common copy number aberrations in pancreatic cancer, but the genes affected by these aberrations are largely unknown. To identify putative amplification target genes in pancreatic cancer, we performed a parallel copy number and expression survey in 13 pancreatic cancer cell lines using a 12,232-clone cDNA microarray, providing an average resolution of 300 kb throughout the human genome. CGH on cDNA microarray allowed highly accurate mapping of copy number increases and resulted in identification of 24 independent amplicons, ranging in size from 130 kb to 11 Mb. Statistical evaluation of gene copy number and expression data across all 13 cell lines revealed a set of 105 genes whose elevated expression levels were directly attributable to increased copy number. These included genes previously reported to be amplified in cancer as well as several novel targets for copy number alterations, such as p21-activated kinase 4 (PAK4), which was previously shown to be involved in cell migration, cell adhesion, and anchorage-independent growth. In conclusion, our results implicate a set of 105 genes that is likely to be actively involved in the development and progression of pancreatic cancer.

SUBMITTER: Mahlamaki EH

PROVIDER: S-EPMC1550328 | biostudies-literature | 2004 Sep-Oct

REPOSITORIES: biostudies-literature

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High-resolution genomic and expression profiling reveals 105 putative amplification target genes in pancreatic cancer.

Mahlamäki Eija H EH Kauraniemi Päivikki P Monni Outi O Wolf Maija M Hautaniemi Sampsa S Kallioniemi Anne A

Neoplasia (New York, N.Y.) 20040901 5

Comparative genomic hybridization (CGH) studies have provided a wealth of information on common copy number aberrations in pancreatic cancer, but the genes affected by these aberrations are largely unknown. To identify putative amplification target genes in pancreatic cancer, we performed a parallel copy number and expression survey in 13 pancreatic cancer cell lines using a 12,232-clone cDNA microarray, providing an average resolution of 300 kb throughout the human genome. CGH on cDNA microarra ...[more]

PMID: 15548351

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Project description:A better understanding of the consequences of recurrent (epi)genetic alterations that occur during cervical carcinogenesis is essential in the search for novel biomarkers. In this study we determined genome-wide expression profiles of 10 squamous cell carcinomas (SCCs), 5 adenocarcinomas (AdCAs) and 6 normal epithelial samples. Expression patterns were subsequently combined with previously determined chromosomal profiles in the same carcinomas. Differential gene expression analysis identified 76 genes with altered expression in carcinomas compared to normal epithelium. Microarray results for a subset of these genes were validated by real-time RT-PCR. Among the differentially expressed genes a relative overrepresentation of genes located at chromosome 3q, one of the most frequently gained areas in SCCs, was observed (false discovery rate (FDR)<0.005). To further investigate the relationship between gene expression and chromosomal alterations 2 statistical approaches were used, i.e. differential gene locus mapping (DIGMAP) and the array CGH expression integration tool (ACE-it). Using these methods we found that increased gene expression was linked to increased gene copy numbers at 1q32.1, 3q13.32-22.3, 3q26.32-27.3, and 20q11.21-13.33, whereas a loss at 11q22.3-25 correlated with recurrent decreased gene expression. Integrated genome-wide chromosomal and transcriptional analysis of cervical carcinomas highlighted 7 genes (i.e. FLJ21291, DTX3L, CCDC14, MCM2, PIK3R4, ATP2C1 and SLC25A36), which were identified by differential gene expression analysis and were located within the chromosomal regions identified by DIGMAP and/or ACE-it as well. Further investigations of these promising marker genes in warranted. Keywords: microarray analysis, array CGH, cervical cancer For microarray mRNA expression analysis 10 SCCs, 5 AdCAs and 6 normal epithelial controls were used. Normal cervical controls consisted of 1 pool of 3 normal cervices distant from tumour, 1 pool of 4 normal ectocervical smears and 1 pool of 5 normal endocervical smears. To expand our number of normal squamous epithelial controls, we included expression profiles of 3 uvulas of non-cancer patients who underwent uvulopalatopharyngoplasty. In addition, we hybridised RNA isolated from 2 different biopsies of the same SCC (SCC12 and SCC13) as a biological replicate. The pool of 4 normal ectocervical smears was hybridised twice as a technical replicate to determine technical variation. Genomic profiling of the same 10 SCCs and 5 AdCAs was done using array CGH (Wilting et al, J Pathol 2006, volume 209, p 220-30).

Project description:BackgroundUrothelial carcinoma (UC) is characterized by nonrandom chromosomal aberrations, varying from one or a few changes in early-stage and low-grade tumors, to highly rearranged karyotypes in muscle-invasive lesions. Recent array-CGH analyses have shed further light on the genomic changes underlying the neoplastic development of UC, and have facilitated the molecular delineation amplified and deleted regions to the level of specific candidate genes. In the present investigation we combine detailed genomic information with expression information to identify putative target genes for genomic amplifications.MethodsWe analyzed 38 urothelial carcinomas by whole-genome tiling resolution array-CGH and high density expression profiling to identify putative target genes in common genomic amplifications. When necessary expression profiling was complemented with Q-PCR of individual genes.ResultsThree genomic segments were frequently and exclusively amplified in high grade tumors; 1q23, 6p22 and 8q22, respectively. Detailed mapping of the 1q23 segment showed a heterogeneous amplification pattern and no obvious commonly amplified region. The 6p22 amplicon was defined by a 1.8 Mb core region present in all amplifications, flanked both distally and proximally by segments amplified to a lesser extent. By combining genomic profiles with expression profiles we could show that amplification of E2F3, CDKAL1, SOX4, and MBOAT1 as well as NUP153, AOF1, FAM8A1 and DEK in 6p22 was associated with increased gene expression. Amplification of the 8q22 segment was primarily associated with YWHAZ (14-3-3-zeta) and POLR2K over expression. The possible importance of the YWHA genes in the development of urothelial carcinomas was supported by another recurrent amplicon paralogous to 8q22, in 2p25, where increased copy numbers lead to enhanced expression of YWHAQ (14-3-3-theta). Homozygous deletions were identified at 10 different genomic locations, most frequently affecting CDKN2A/CDKN2B in 9p21 (32%). Notably, the latter occurred mutually exclusive with 6p22 amplifications.ConclusionThe presented data indicates 6p22 as a composite amplicon with more than one possible target gene. The data also suggests that amplification of 6p22 and homozygous deletions of 9p21 may have complementary roles. Furthermore, the analysis of paralogous regions that showed genomic amplification indicated altered expression of YWHA (14-3-3) genes as important events in the development of UC.

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High-resolution genomic and expression profiling reveals 105 putative amplification target genes in pancreatic cancer.

Publications

High-resolution genomic and expression profiling reveals 105 putative amplification target genes in pancreatic cancer.

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