Unknown,Transcriptomics,Genomics,Proteomics

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Multiple genes at the chromosome 20q amplicon contribute to colorectal adenoma to carcinoma progression

ABSTRACT: Chromosomal instability (CIN) is the hallmark of colorectal adenoma to carcinoma progression in 85% of cases, with 20q gain as the most prominent aberration. Yet, the oncogenes at this chromosomal gain are still largely unknown. Here, we aimed to identify oncogenes at 20q involved in colorectal adenoma to carcinoma progression by measuring the effect of 20q gain on gene expression in this amplicon. Segmentation of DNA copy number changes on 20q was performed by array CGH in 67 colorectal adenomas and carcinomas. Additionally, robust analysis of mRNA expression in these segments was performed in 68 adenomas and carcinomas. This approach revealed seven genes to be important in CIN related adenoma to carcinoma progression. These genes may both serve as highly specific biomarkers for presence of high-risk precursor lesions as well as potential targets for pharmaceutical intervention. Keywords: Integration of array CGH and expression microarrays in colorectal cancer progression We performed array CGH on a panel of 41 progressed adenomas, from which the adenoma and carcinoma components were separately analysed (total, 82 samples). The DNA obtained from these samples was extracted from formalin-fixed, paraffin-embedded material. Additionally we analysed a series of independent frozen adenomas and carcinomas by array CGH (34 adenomas and 33 carcinomas) and expression microarrays (37 adenomas and 31 carcinomas). For array-CGH we used as reference DNA for all samples, a pool of 10 normal individuals. For expression microarrays we used as reference a commercial available RNA (pool of different cancer cell lines), from Strategene. No replicates nor dye swaps were done.

ORGANISM(S): Homo sapiens

SUBMITTER: Gerrit Meijer

PROVIDER: E-GEOD-8067 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Multiple putative oncogenes at the chromosome 20q amplicon contribute to colorectal adenoma to carcinoma progression.

Carvalho B B Postma C C Mongera S S Hopmans E E Diskin S S van de Wiel M A MA van Criekinge W W Thas O O Matthäi A A Cuesta M A MA Terhaar Sive Droste J S JS Craanen M M Schröck E E Ylstra B B Meijer G A GA

Gut 20081001 1

<h4>Objective</h4>This study aimed to identify the oncogenes at 20q involved in colorectal adenoma to carcinoma progression by measuring the effect of 20q gain on mRNA expression of genes in this amplicon.<h4>Methods</h4>Segmentation of DNA copy number changes on 20q was performed by array CGH (comparative genomic hybridisation) in 34 non-progressed colorectal adenomas, 41 progressed adenomas (ie, adenomas that present a focus of cancer) and 33 adenocarcinomas. Moreover, a robust analysis of alt ...[more]

PMID: 18829976

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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:Cervical cancer develops from pre-cancerous high-grade cervical intraepithelial neoplasia (CIN) lesions harbouring a transforming infection with high-risk human papillomavirus (hrHPV), which is characterised by p16INK4a overexpression. Since it takes one or more decades for these pre-cancerous lesions to progress to invasive squamous cell carcinomas (SCCs), it is obvious that they are heterogeneous in terms of duration of existence and progression risk. We performed array-based comparative genomic hybridisation (array CGH) of 46 p16INK4a immuno-positive CIN2/3 lesions to determine whether this heterogeneity is reflected in their chromosomal profiles. Chromosomal profiles of CIN2/3 lesions were related to those of invasive cervical squamous cell carcinomas (SCCs) and promoter methylation of the CADM1 gene, a tumour suppressor gene known to be functionally involved in the tumorigenic phenotype of cervical cancer cells. Frequent alterations found in CIN2/3 lesions included gains located at chromosome 1, 3, 7 and 20 and losses located at 4, 11, 16, 17 and 19. Unsupervised hierarchical clustering identified two subsets of CIN2/3 lesions, chromosomal profiles of one of which closely resembled invasive SCCs. Gains of 1, 3q and 20 were characteristic for CIN2/3 lesions with chromosomal signatures resembling carcinomas. In addition, dense promoter methylation of the CADM1 gene was significantly more frequent in these CIN2/3 lesions (p=0.004). No chromosomal alterations were detected in one p16INK4a positive and five p16INK4a negative CIN1 lesions. These findings suggest that biomarkers associated with gains at chromosomes 1, 3q and 20 are potential hallmarks of advanced p16INK4a positive CIN2/3 lesions with a high short-term risk of progression. Genomic DNA of 46 high-grade cervical lesions was hybridised to 5K CGH BAC microarrays (5K) produced at the Microarray facility of the VU Medical Center. In total 4632 BAC clones with known chromosomal location were spotted in triplicate, which included the 1Mb resolution Sanger BAC clone set and a subset of clones from the Children’s Hospital Oakland Research Institute (CHORI). All samples were labelled with Cy3 and hybridised together with a pool of normal male reference DNA labelled with Cy5. Hybridisations were essentially performed as described by Snijders et al (Nature Genetics 2001). Both pre-hybridisation and hybridisation were performed in a hybridisation station (HybStation12 – Perkin Elmer Life Sciences). Hybridised arrays were scanned using a G2505B scanner (Agilent, Wilmington, DE, USA). Spots were quantified using ImaGene 5.6.1 software (BioDiscovery Ltd, Marina del Rey, CA, USA) with default settings for the flagging of bad quality spots. Genomic DNA of 6 CIN1 lesions was hybridised on CGH oligo microarrays (44K) produced by Agilent following the manufacturer’s protocol against the same normal reference pool. Hybridised arrays were scanned using the same scanner (G2505B, Agilent). Quantification of these arrays was done using Feature Extraction software version 9.5.1 (Agilent).

Project description:We superimposed array comparative genomic hybridization (aCGH) data onto existing expression array profiles (GSE3892) to sift out the pivotal genes underlying the pathogenesis of a well defined series of diffuse large B-cell lymphomas (DLBCL). 280 gained and over-expressed genes were identified, located on chromosomes 1q, 3q, 7, 12p12, 18q and 21q. At the most frequently gained region the oncogene MDMX/MDM4 was concurrently over-expressed, which is a critical regulator of p53 function. In regions of frequent chromosomal loss, 36 genes were concurrently down-regulated, restricted to 6q and 15p. These putative tumor suppressor genes included PERP, MAP3K5, CCNDBP1 and Î²2M, and loss of 6q was associated with poor clinical outcome. Genes identified and chromosomal regions validated in an independent series of DLBCL patients. Overall design fields: Copy number profiles (array CGH) of a series of 42 Diffuse large B-cell lymphoma patient samples were analyzed a) for frequency of aberrations and b) for impact on gene expression. No duplicate samples or dye-swaps were analyzed. a) Statistical analysis of Array CGH data Calling: Areas of gains and losses and their frequencies throughout the dataset were determined from the Bluefuse ratios within the statistical package â??CGHcallâ?? (van de Wiel et al., 2007). Briefly, after smoothing outliers and median normalization, â??DNAcopyâ?? segmentation (Olshen et al., 2004) was applied within CGHcall, after which a call was assigned to each position on the genome. Within CGHcall the probabilities of the calls were determined per chromosomal arm, and a cellularity correction of 0.75 was applied to each sample because tumor cellularity in all DLBCL is estimated to be maximal 75%, taking into account all stromal, endothelial en infiltrating lymphocytes. After calling, we applied â??CGHregionsâ?? (van de Wiel and van Wieringen 2007) to determine regions of consecutive clones with highly similar calls for all samples. This dimension reduction further increases robustness and statistical power for downstream statistical analyses. Called data were used for all downstream analyses. b) Integration with expression data To integrate called array CGH data with expression array data, the array CGH and expression integration tool, ACE-it (van Wieringen et al., 2006), was used. For ACE-it analysis chromosomal amplifications were included in the gains. ACE-it uses the one-sided Wilcoxon rank sum to test which chromosomal aberrations recurrently affect RNA expression and adjust p-values for multiple testing. Only those clones were taken into account which had at least 20% (9) of the samples in one of the other calling states (gain or loss). Only genes were considered relevant with a false discovery rate of <0.1. References - Olshen AB, Venkatraman ES, Lucito R, Wigler M (2004) Circular binary segmentation for the analysis of array-based DNA copy number data. Biostatistics 5: 557-72. - van de Wiel MA, Kim KI, Vosse SJ, van Wieringen WN, Wilting SM, Ylstra B (2007) CGHcall: calling aberrations for array CGH tumor profiles. Bioinformatics 23: 892-4. - van de Wiel MA, van Wieringen WN. CGHregions: dimension reduction for array CGH data with minimal information loss. Cancer Informatics. In press 2007. - van Wieringen WN, Belien JA, Vosse SJ, Achame EM, Ylstra B (2006) ACE-it: a tool for genome-wide integration of gene dosage and RNA expression data. Bioinformatics 22: 1919-20.

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Dataset Information

Multiple genes at the chromosome 20q amplicon contribute to colorectal adenoma to carcinoma progression

Publications

Multiple putative oncogenes at the chromosome 20q amplicon contribute to colorectal adenoma to carcinoma progression.

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