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Candidate driver genes in focal chromosomal aberrations of stage II colon cancer

ABSTRACT: Chromosomal instable colorectal cancer is marked by specific large chromosomal copy number aberrations. Recently, focal aberrations of 3Mb or smaller have been identified as a common phenomenon in cancer. Inherent to their limited size, these aberrations harbour one or few genes. The aim of this study is to identify recurrent focal chromosomal aberrations and their candidate driver genes in a well defined series of stage II colon cancers and assess their potential clinical relevance. High resolution DNA copy number profiles were obtained from 38 formalin fixed paraffin embedded colon cancer samples with matched normal mucosa as a reference using array comparative genomic hybridization. In total, 81 focal chromosomal aberrations were identified that harboured 177 genes. Statistical validation of focal aberrations and identification of candidate driver genes was performed by enrichment analysis and mapping copy number and mutation data of colorectal-, breast-, pancreatic cancer and glioblastomas to loci of focal aberrations in stage II colon cancer. This analysis demonstrated a significant overlap with previously identified focal amplifications in colorectal cancer, but not with cancers from other sites. In contrast, focal deletions seem less tumour type specific since they also show significant overlap with focal deletions of other sites. Focal deletions detected are significantly enriched for cancer genes and genes frequently mutated in colorectal cancer. The mRNA expression of these genes is significantly correlated with DNA copy number status, supporting the relevance of focal aberrations. Loss of 5q34 and gain of 13q22.1 were identified as independent prognostic factors of survival in this series of patients. In conclusion, focal chromosomal copy number aberrations in stage II colon cancer are enriched in cancer genes which contribute to and drive the process of colorectal cancer development. DNA copy number status of these genes correlate with mRNA expression and some are associated with clinical outcome. 38 Stage II colorectal cancer (CRC) tissue samples (FFPE) of which 19 were done on expression arrays. One sample (Stage II colorectal cancer tissue samples (FFPE) 26) was also done on the 135K NimbleGen array. Fresh frozen and FFPE of the same CRC stage I sample was done on 105K agilent. The fresh frozen was across array in silico set out against a pool of blood of 18 healthy females.

ORGANISM(S): Homo sapiens

SUBMITTER: Serge Smeets

PROVIDER: E-GEOD-17047 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Candidate driver genes in focal chromosomal aberrations of stage II colon cancer.

Brosens Rebecca P M RP Haan Josien C JC Carvalho Beatriz B Rustenburg François F Grabsch Heike H Quirke Philip P Engel Alexander F AF Cuesta Miguel A MA Maughan Nicola N Flens Marcel M Meijer Gerrit A GA Ylstra Bauke B

The Journal of pathology 20100801 4

Chromosomal instable colorectal cancer is marked by specific large chromosomal copy number aberrations. Recently, focal aberrations of 3 Mb or smaller have been identified as a common phenomenon in cancer. Inherent to their limited size, these aberrations harbour one or few genes. The aim of this study was to identify recurrent focal chromosomal aberrations and their candidate driver genes in a well-defined series of stage II colon cancers and assess their potential clinical relevance. High-reso ...[more]

PMID: 20593488

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Project description:Background & Aims: The metastatic process is complex and remains a major obstacle in the management of colorectal cancer (CRC). To gain a better insight into the biologic events driving the metastatic process we investigated genomic aberrations in a large cohort of matched CRC primaries and distant metastases from various sites. Methods: In total, 62 primary colorectal cancers, 62 matched normal specimens, and 68 matched metastases (from liver, lung, ovary, omentum, and distant lymph nodes) were analyzed by high resolution array comparative genomic hybridization (array CGH) for DNA copy number changes. Findings were validated using a publicly available dataset consisting of 21 primary tumors and matched liver metastases. Fluorescence in situ hybridization (FISH) was used to confirm some of the DNA copy number changes observed. Results: Overall patterns of DNA copy number aberrations were highly similar between primary tumors and their metastases, confirming clonality. Additional copy number aberrations in metastasis are rare and rather than recurrent they were sporadic for individual patients. The only recurrent differences between primary tumors and their metastases were two chromosomal regions, 6q21 and 8q24.21 encompassing the MYC oncogene, that coamplified in three metastases of two patients (3.2%). FISH analysis confirmed the high level co-amplification in the metastasis, which were not detected in their primary tumors. Conclusions: Primary CRC and their metastases show highly similar patterns of DNA copy number changes, additional copy number aberrations in metastasis are rare and recurrences exceptional. These observations are consistent with the hypothesis that the metastatic potential is predestined early in the development of the primary tumor. In total, 62 primary colorectal cancers, 62 matched normal specimens, and 68 matched metastases (liver, lung, ovarian, omentum and distant lymph nodes) were analyzed by high resolution array comparative genomic hybridization (array CGH).

Project description:Chromosomal instable colorectal cancer is marked by specific large chromosomal copy number aberrations. Recently, focal aberrations of 3Mb or smaller have been identified as a common phenomenon in cancer. Inherent to their limited size, these aberrations harbour one or few genes. The aim of this study is to identify recurrent focal chromosomal aberrations and their candidate driver genes in a well defined series of stage II colon cancers and assess their potential clinical relevance. High resolution DNA copy number profiles were obtained from 38 formalin fixed paraffin embedded colon cancer samples with matched normal mucosa as a reference using array comparative genomic hybridization. In total, 81 focal chromosomal aberrations were identified that harboured 177 genes. Statistical validation of focal aberrations and identification of candidate driver genes was performed by enrichment analysis and mapping copy number and mutation data of colorectal-, breast-, pancreatic cancer and glioblastomas to loci of focal aberrations in stage II colon cancer. This analysis demonstrated a significant overlap with previously identified focal amplifications in colorectal cancer, but not with cancers from other sites. In contrast, focal deletions seem less tumour type specific since they also show significant overlap with focal deletions of other sites. Focal deletions detected are significantly enriched for cancer genes and genes frequently mutated in colorectal cancer. The mRNA expression of these genes is significantly correlated with DNA copy number status, supporting the relevance of focal aberrations. Loss of 5q34 and gain of 13q22.1 were identified as independent prognostic factors of survival in this series of patients. In conclusion, focal chromosomal copy number aberrations in stage II colon cancer are enriched in cancer genes which contribute to and drive the process of colorectal cancer development. DNA copy number status of these genes correlate with mRNA expression and some are associated with clinical outcome.

Project description:Cervical cancer results from the accumulation of (epi)genetic aberrations following persistent infection with high-risk human papillomavirus (HPV). In order to define genetic aberrations associated with cervical carcinogenesis, chromosomal profiles of high-grade cervical intraepithelial neoplasia (CIN) were generated. Common aberrations usually encompass large genomic regions and contain numerous genes, hampering identification of actual driver genes. Consequently, direct evidence of chromosomal alterations actively contributing to cervical carcinogenesis has been lacking so far. By analyzing 60 high-grade CIN with high resolution arrayCGH we identified focal chromosomal aberrations that each harbour only one or a few genes. In total 74 focal aberrations were identified encoding 305 genes. Analysis of genes located within these focal aberrations, using two independent expression microarray datasets, revealed concurrent altered expression in high-grade CIN and/or cervical carcinomas compared to normal cervical samples for 8 genes: ATP13A3, HES1, OPA1, HRASLS, EYA2, ZMYND8, APOBEC2 and NCR2. Gene silencing of EYA2, located within a focal gain at 20q13, significantly reduced viability and migratory capacity of HPV16-transformed keratinocytes. Interestingly, for hsa-miR-375, located within the most frequently identified focal loss at 2q35, a direct correlation between a (focal) loss and significantly reduced expression was found. Down-regulation of hsa-miR-375 expression during cervical carcinogenesis was confirmed in a second independent series of cervical tissues. Moreover, ectopic expression of hsa-miR-375 in 2 cervical carcinoma cell lines reduced cellular viability. In conclusion, our data provide a proof of concept that chromosomal aberrations are actively contributing to HPV-induced carcinogenesis and identify EYA2 and hsa-mir-375 as oncogene and tumor suppressor gene, respectively. DNA from microdissected tissues: 60 samples total. 11 high-grade CIN, <5yr preceding hrHPV infection, 43 high-grade CIN >5yr preceding hrHPV infection, 6 CIN3 adjacent to SCC

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.

Project description:Formalin-fixed, paraffin-embedded (FFPE) archival tissue is an important source of DNA material. The most commonly used technique to identify copy number aberrations from chromosomal DNA in tumorigenesis is array comparative genomic hybridization (aCGH). Although copy number analysis using DNA from FFPE archival tissue is challenging, several research groups have reported high quality and reproducible DNA copy number results using aCGH. Aim of the present study is to compare aCGH platforms suitable for copy number analysis using FFPE derived DNA. Two dual channel aCGH platforms (Agilent and NimbleGen) and a single channel SNP based platform (Affymetrix), were evaluated using seven FFPE colon cancer samples, median absolute deviation (MAD), deflection, signal-to-noise ratio (SNR) and DNA input requirements were used as quality criteria. Large differences were observed in MAD values and deflection between platforms; Agilent and NimbleGen showed better MAD values (0.13 for both) compared to Affymetrix (0.22). Contrary, Affymetrix showed a better deflection of 0.94, followed by 0.71 for Agilent and 0.51 for NimbleGen. Since the deflection compensates for the MAD the Signal to Noise Ratios (SNR) were comparable; Agilent ranks first, Affymetrix second and NimbleGen third with SNRs of 3.9, 3.6 and 3.3 respectively. DNA input amounts of 40ng are sufficient for high quality profiles with Affymetrix. For Agilent DNA input amounts of 50ng are sufficient for high quality profiles. For results of similar quality NimbleGen requires at least 100ng. Copy number analysis using DNA derived from FFPE archival material is feasible and shows reproducible results on high-resolution copy number platforms. Input amounts of DNA from FFPE material lower than recommended still yield high quality profiles without additional amplification steps. Overall study comprises 6 samples analyzed across three platforms with an additional dilution range (5 concentrations) of a seventh sample on two platforms. This Series represents Agilent platform-derived data.

Project description:Individuals who present with premalignant endobronchial lesions are considered at high risk of lung cancer. Nonetheless, premalignant lesions behave erratically and only a minority progresses towards lung cancer. Therefore, biomarkers need to be discovered that can aid in assessing an individual’s risk for subsequent cancer to better tailor treatment choices and avoid unnecessary follow-up procedures. We recently proposed a classifier of DNA copy number alterations (CNAs) at 3p26.3-p11.1, 3q26.2-29, and 6p25.3-24.3 as risk predictor for endobronchial cancer. The current study was set out to validate the classifier among an independent series of premalignant endobronchial lesions with various histological grades. A series of 36 endobronchial premalignant lesions (8 squamous metaplasia, and 28 various grades of dysplasia) identified during autofluorescence bronchoscopy of 12 case subjects who had carcinoma in situ or carcinoma (≥CIS) during follow-up bronchoscopy at the initial site and 24 control subjects who remained cancer-free, was subjected to array Comparative Genomic Hybridization (arrayCGH). DNA copy number profiles were related to lesion outcome. Prediction accuracy of the previously defined molecular classifier to predict endobronchial cancer in this series was determined. Unsupervised hierarchical clustering analysis revealed a significant association between cluster assignment and lesion outcome (p< 0.001), independent of histological grade, with quiescent profiles in controls (24/24) and aberrant profiles in the majority of cases (9/12). Our pre-defined classifier demonstrated 92% accuracy for predicting cancer outcome in the current sample series. Our validated classifier holds great promise for stratification of patients with premalignant endobronchial lesions for risk of subsequent cancer. Fresh frozen specimens of 36 premalignant endobronchial biopsies. Test samples were compared to an external pool of normal male/female reference DNA.

Dataset Information

Candidate driver genes in focal chromosomal aberrations of stage II colon cancer

Publications

Candidate driver genes in focal chromosomal aberrations of stage II colon cancer.

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