Analysis Of Copy Number Changes Research Articles

Abstract 820: Genomics based personalized oncology of cancer of unknown primary

Abstract Cancers of unknown primary site (CUPs) represent a heterogeneous group of metastatic tumors, which accounts for 3-5% of malignancies. Due to the poor prognosis and limited local and systemic treatment options, there is an urgent need for improvement of molecularly driven treatment strategies. We investigated the molecular profile and clinical course of 70 patients enrolled in a prospective precision oncology registry trial conducted by the National Center for Tumor Diseases (NCT) Heidelberg/Dresden and the German Cancer Consortium (DKTK) that addresses younger adults with advanced-stage cancer across histologies as well as patients with rare tumors (NCT/DKTK MASTER). Molecular analyses included whole genome sequencing (WGS, n=29), whole exome sequencing (WES, n=41) and transcriptome analysis (n=55). All patients were diagnosed with CUP-syndrome, 61/70 (87.1%) of diagnoses fulfilled the ESMO Clinical Practice Guidelines. Progression free survival (PFS) of the first treatment based on MASTER (PFS2) was compared to the PFS of the last prior systemic treatment (PFS1) in each individual patient. Within the coding sequence, we identified 0 to 1386 nonsynonymous point mutations (SNVs, median=41) and 0 to 38 insertions/deletions (indels, median=3) per sample. Hypermutation (≥100 SNVs and indels) was observed in 14 samples. Mutations of TP53 and KRAS were significantly enriched. Analysis of copy-number changes (CNVs) was performed in 51 samples (27 WGS and 24 WES) and revealed complex CNV profiles in most cases. Gains and losses involved single arms or whole chromosomes. Gains in chromosome 8q, 1q and 7 and losses in chromosome 6q and 17p occurred in more than 40% of the patients. Fusions of EML4-ALK and FGFR2 were found in three and six cases, respectively. In one case, pathological reevaluation for NUT midline carcinoma was recommended based on a NUTM1-MXI1 fusion. In total, pathological reevaluation based on characteristic genetic events was recommended in five cases. Germline analysis of 70 cases revealed five pathogenic variants (ACMG Class 5) in CHEK2, BRCA1, CDKN2A, NBN and ERCC3. In addition, one likely pathogenic variant (ACMG Class 4) was found in FH. The molecular tumor board recommended targeted therapy in 56/70 (80.0%) patients which could be applied in 20/56 (35.7%) cases. The molecularly driven treatment approaches translated into a median PFS2/1 ratio of 2.25 (n=17). Median PFS1 was 89 days (range 31-304, n=17) compared to a median PFS2 of 180 days (range 50-805, n=17). For three patients in which PFS1 could not be determined median PFS2 was 305 days (range 182-336). We demonstrate that a comprehensive molecular analysis of CUPs provides clinically relevant information and additional, molecularly stratified treatment approaches in many cases. These targeted therapies can be highly beneficial even in heavily pretreated patients. Citation Format: Maximilian Werner, Lino Möhrmann, Małgorzata Oleś, Andreas Mock, Arne Jahn, Simon Kreutzfeldt, Sebastian Uhrig, Martina Fröhlich, Barbara Hutter, Daniela Richter, Gina Rüter, Ivan Jelas, Rainer Hamacher, Johanna Falkenhorst, Sebastian Wagner, Christian Brandts, Melanie Börries, Anna Illert, Klaus Metzeler, Benedikt Westphalen, Alexander Desuki, Thomas Kindler, Albrecht Stenzinger, Evelin Schröck, Benedikt Brors, Peter Horak, Christoph Heining, Stefan Fröhling, Hanno Glimm. Genomics based personalized oncology of cancer of unknown primary [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 820.

Simultaneous FLT3, NPM1 and DNMT3A mutations in adult patients with acute myeloid leukemia – case study

Abstract Background: Nowadays, cytogenetics and molecular genetics, but not only, are mandatory in acute myeloid leukemia (AML) management, as a consequence of their impact on AML pathogenesis, classification, risk-stratification, prognosis and treatment. Objective: The aim of our study was to present our algorithm for the analysis of copy number changes, aneuploidies and somatic mutations focusing on a rare AML case positive for four somatic mutations. Methods: Cytogenetic analysis, Multiplex Ligationdependent Probe Amplification (MLPA) analysis, somatic mutation analysis (for FLT3 ITD, FLT3 D835, DNMT3A R882 and NPM1 c.863_864ins) by using several PCR techniques and also next-generation sequencing (NGS) analysis were performed. Results: Cytogenetic analysis did not reveal structural or numerical chromosomal anomalies. The patient’s DNA showed no copy number changes or aberrations (CNAs) following the MLPA analysis. By using several molecular technologies we found four mutations: FLT3-ITD, FLT3 D835 (c.2504A>T, D835V), DNMT3A R882C, and NPM1 c.863_864insTCTG. Challenges, benefits, applications and the limitations of each molecular technique used for the investigation of the mentioned mutation, and not only, are also described. Conclusion: All these techniques can be useful in the diagnosis of AML patients, each of them covering the limits of the other technique. New strategies for a positive, fast, accurate and reliable diagnosis are mandatory in cases with AML.

Highly Multiplexed Fluorescence in Situ Hybridization for in Situ Genomics

The quantification of changes in gene copy number is critical to our understanding of tumor biology and for the clinical management of cancer patients. DNA fluorescence in situ hybridization is the gold standard method to detect copy number alterations, but it is limited by the number of genes one can quantify simultaneously. To increase the throughput of this informative technique, a fluorescent bar-code system for the unique labeling of dozens of genes and an automated image analysis algorithm that enabled their simultaneous hybridization for the quantification of gene copy numbers were devised. We demonstrate the reliability of this multiplex approach on normal human lymphocytes, metaphase spreads of transformed cell lines, and cultured circulating tumor cells. It also opens the door to the development of gene panels for more comprehensive analysis of copy number changes in tissue, including the study of heterogeneity and of high-throughput clinical assays that could provide rapid quantification of gene copy numbers in samples with limited cellularity, such as circulating tumor cells.

Pan-cancer analysis of copy number changes in programmed death-ligand 1 (PD-L1, CD274) - associations with gene expression, mutational load, and survival.

Inhibition of the PD-L1 (CD274) - PD-1 axis has emerged as a powerful cancer therapy that prevents evasion of tumor cells from the immune system. While immunohistochemical detection of PD-L1 was introduced as a predictive biomarker with variable power, much less is known about copy number alterations (CNA) affecting PD-L1 and their associations with expression levels, mutational load, and survival. To gain insight, we employed The Cancer Genome Atlas (TCGA) datasets to comprehensively analyze 22 major cancer types for PD-L1 CNAs. We observed a diverse landscape of PD-L1 CNAs, which affected focal regions, chromosome 9p or the entire chromosome 9. Deletions of PD-L1 were more frequent than gains (31% vs. 12%) with deletions being most prevalent in melanoma and non-small cell lung cancer. Copy number gains most frequently occurred in ovarian cancer, head and neck cancer, bladder cancer, cervical and endocervical cancer, sarcomas, and colorectal cancers. Fine-mapping of the genetic architecture revealed specific recurrently amplified and deleted core regions across cancers with putative biological and clinical consequences. PD-L1 CNAs correlated significantly with PD-L1 mRNA expression changes in many cancer types, and tumors with PD-L1 gains harbored significantly higher mutational load compared to non-amplified cases (median: 78 non-synonymous mutations vs. 40, P = 7.1e-69). Moreover, we observed that, in general, both PD-L1 amplifications and deletions were associated with dismal prognosis. In conclusion, PD-L1 CNAs, in particular PD-L1 copy number gains, represent frequent genetic alterations across many cancers, which influence PD-L1 expression levels, are associated with higher mutational loads, and may be exploitable as predictive biomarker for immunotherapy regimens. © 2016 Wiley Periodicals, Inc.

Abstract 4922: Analysis of copy number changes in HNSCC by MLPA

Abstract Gene amplification is a common finding in a broad spectrum of tumor types, often leading to increased levels of gene expression, a mechanism by which genetic changes contribute to the initiation or progression of cancer. HNSCC is among the neoplasias that frequently show amplification of specific genomic regions. Previous cytogenetic and molecular genetic studies by Fluorescence in situ Hybridization (FISH) and comperative genome hybridization (CGH) and other molecular methods showed that frequently amplified chromosomal regions in primary HNSCC tumors are 3q, 8q, 8p, 11q, 9q. Generally, proto-oncogenes reside in these amplified regions and amplification of these often leads to increased levels of gene expression. Therefore, in this study we investigated amplification of 22 different oncogenes mapping to these regions. The analyses were performed by MLPA on an ABI 3100 genetic analyzer and relative peak areas of the amplification products were evaluated using the Coffalyser MLPA analysis software. Analysis of 50 HNSCC tumor tissue samples showed that the most frequently amplified genes were from the regions 17q12 (MED1), 11q13.3 (CCND1), 8q (MYC and MTDH) and 8p (ZNF703) with frequencies of 24%, 24%, 20%, 20% and 18%, respectively. In total, Copy Number Alterations of the CCND1 and MED1 genes were observed in 12 of 50 tumor samples. For the CCND1 gene 6 of these alterations were heterozygous duplications and the remaining 6 were triplications. On the other hand, for the MED1 gene duplications were observed in 8 samples and trriplications were detected in 4 samples. Triplication of the MTDH gene was not observed in any of the amplified samples. However, one third of the ZNF703 amplifications were triplications. Amplification of the CCND1 and MYC genes are frequently observed in different types of cancers including HNSCC. More recently overexpression of MTDH has been associated with lymph node metastasis and poor-survival in HNSCC. However, to our knowledge there is no data in the literature investigating the ZNF703 gene in HNSCC. Our data indicate that ZNF703 may represent a candidate gene the role of which warrants more detailed analysis in HNSCC. Citation Format: Nejat Dalay, Orkun Gurbuz, Elif Baltaci, Emin Karaman, Nur Buyru. Analysis of copy number changes in HNSCC by MLPA. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4922. doi:10.1158/1538-7445.AM2015-4922

Novel genetic aberrations in breast phyllodes tumours: comparison between prognostically distinct groups.

Phyllodes tumours of the breast are uncommon fibroepithelial neoplasms which pose management challenges due to difficulties in accurate prediction of clinical behaviour, as histological assessment has its limitations. Molecular studies have improved the understanding of these rare tumours but such findings are scant. We aimed to investigate genetic aberrations in phyllodes tumours stratified according to clinical behaviour, to identify potential genes contributing to disease progression. Twenty phyllodes tumours were separated into prognostically distinct categories depending on whether they had recurred/metastasized within the follow-up period. DNA extracted from FFPE materials was subjected to Affymetrix OncoScan™ FFPE Express molecular inversion probe microarray platform for analysis of copy number changes and mutational status. Results were cross validated with Sanger sequencing, FISH and immunohistochemistry. A higher number of chromosomal aberrations were observed in cases which recurred/metastasized, with median events of 19 compared to 3.5 in cases which did not recur/metastasize. High-level amplification and homozygous deletions were detected exclusively in the former group. Regions of high-level amplification included MDM4 (1q32.1), RAF1 (3p25), EGFR (7p12) and PDZD2 (5p13.3). EGFR amplification was confirmed on FISH and accompanied by intense EGFR immunostaining. Regions of homozygous deletion included CDKN2A (9p21) and MACROD2 (20p12.1). Homozygous deletion of 9p21 which involved CDKN2A was accompanied by loss of protein expression. No mutations were identified in all samples. These findings provide insights into identifying target genes and pathways exploited by phyllodes tumours, which would aid future development of individualised therapy.

Analysis of copy number changes on chromosome 16q in male breast cancer by multiplex ligation-dependent probe amplification

Gene copy number changes have an important role in carcinogenesis and could serve as potential biomarkers for prognosis and targets for therapy. Copy number changes mapping to chromosome 16 have been reported to be the most frequent alteration observed in female breast cancer and a loss on 16q has been shown to be associated with low grade and better prognosis. In the present study, we aimed to characterize copy number changes on 16q in a group of 135 male breast cancers using a novel multiplex ligation-dependent probe amplification kit. One hundred and twelve out of 135 (83%) male breast cancer showed copy number changes of at least one gene on chromosome 16, with frequent loss of 16q (71/135; 53%), either partial (66/135; 49%) or whole arm loss (5/135; 4%). Losses on 16q were thereby less often seen in male breast cancer than previously described in female breast cancer. Loss on 16q was significantly correlated with favorable clinicopathological features such as negative lymph node status, small tumor size, and low grade. Copy number gain of almost all genes on the short arm was also significantly correlated with lymph node negative status. A combination of 16q loss and 16p gain correlated even stronger with negative lymph node status (n=112; P=0.012), which was also underlined by unsupervised clustering. In conclusion, copy number loss on 16q is less frequent in male breast cancer than in female breast cancer, providing further evidence that male breast cancer and female breast cancer are genetically different. Gain on 16p and loss of 16q identify a group of male breast cancer with low propensity to develop lymph node metastases.

Genome-Wide DNA Copy Number Analysis of Desmoplastic Infantile Astrocytomas and Desmoplastic Infantile Gangliogliomas

Little is known about the molecular features of desmoplastic infantile ganglioglioma (DIG) and desmoplastic infantile astrocytoma (DIA). We performed a genome-wide DNA copy number analysis in combination with a multiplex ligation-dependent probe amplification-based analysis of copy number changes of candidate genes in 4 DIAs and 10 DIGs. Molecular inversion probe (MIP) assay showed that large chromosomal alterations were rare among DIG and DIA. Focal recurrent genomic losses were observed in chromosome regions such as 5q13.3, 21q22.11, and 10q21.3 in both DIA and DIG. Principal component analysis did not show any significant differences between the molecular profiles of DIG and DIA, and a hierarchical cluster analysis did not clearly separate the 2 tumor groups according to their molecular profiles. In 6 cases, gain of genomic material at 7q31 (corresponding to MET gene) was found in multiplex ligation-dependent probe amplification (MLPA) analysis. Furthermore, two cases showed gain at 4q12, and a single case showed BRAF mutation. In agreement with previous analyses, this study demonstrates the absence of consistent recurrent chromosomal alterations in DIA and DIG and overall rarity of the BRAF mutation in these tumors. Notably, these results suggest that DIA and DIG represent a histologic spectrum of the same tumor rather than 2 separate entities.

Association between genomic alterations and metastatic behavior of colorectal cancer identified by array‐based comparative genomic hybridization

Colorectal cancers (CRCs) exhibit multiple genetic alterations, including allelic imbalances (copy number alterations, CNAs) at various chromosomal loci. In addition to genetic aberrations, DNA methylation also plays important roles in the development of CRC. To better understand the clinical relevance of these genetic and epigenetic abnormalities in CRC, we performed an integrative analysis of copy number changes on a genome-wide scale and assessed mutations of TP53, KRAS, BRAF, and PIK3CA and DNA methylation of six marker genes in single glands isolated from 39 primary tumors. Array-based comparative genomic hybridization (array-CGH) analysis revealed that genomic losses commonly occurred at 3q26.1, 4q13.2, 6q21.32, 7q34, 8p12-23.3, 15qcen and 18, while gains were commonly found at 1q21.3-23.1, 7p22.3-q34, 13q12.11-14.11, and 20. The total numbers and lengths of the CNAs were significantly associated with the aberrant DNA methylation and Dukes' stages. Moreover, hierarchical clustering analysis of the array-CGH data suggested that tumors could be categorized into four subgroups. Tumors with frequent DNA methylation were most strongly enriched in subgroups with infrequent CNAs. Importantly, Dukes' D tumors were enriched in the subgroup showing the greatest genomic losses, whereas Dukes' C tumors were enriched in the subgroup with the greatest genomic gains. Our data suggest an inverse relationship between chromosomal instability and aberrant methylation and a positive association between genomic losses and distant metastasis and between genomic gains and lymph node metastasis in CRC. Therefore, DNA copy number profiles may be predictive of the metastatic behavior of CRCs.

Assessment of chromosomal imbalances in CIMP-high and CIMP-low/CIMP-0 colorectal cancers

Data presented in a number of recent studies have revealed a negative correlation between CpG island methylator phenotype (CIMP) and chromosomal instability (CIN) measured by a loss of heterozygosity (LOH) of selected loci, suggesting that CIN and CIMP represent two independent mechanisms in sporadic colorectal cancer (CRC) carcinogenesis. However, CIN is a heterogeneous phenomenon, which may be studied not only by employing LOH analysis but also by observing chromosomal imbalances (gains and deletions). The current study aimed to investigate the relationship between CIMP and chromosomal gains and deletions (assessed by comparative genomic hybridization) in a group of 20 CIMP-high and 79 CIMP-low/CIMP-0 CRCs. Our results revealed that the mean numbers of gains and of total chromosomal imbalances were significantly greater (p = 0.004 and p = 0.007, respectively) in the CIMP-low/CIMP-0 group compared to the CIMP-high group, while no significant difference was observed between the mean numbers of losses (p = 0.056). The analysis of copy number changes of 41 cancer-related genes by multiplex ligation-dependent probe amplification showed that CRK gene was exclusively deleted in CIMP-low/CIMP-0 tumors (p = 0.02). Given that chromosomal losses play an important role in tumor suppressor inactivation and chromosomal gains, in the activation of proto-oncogenes, we hypothesize that tumor suppressor inactivation plays similar roles in both CIMP-high and CIMP-low/CIMP-0 CRCs, while the predominance of chromosomal gains in CIMP-low/CIMP-0 tumors may suggest that the activation of proto-oncogenes is the underlying mechanism of CIMP-low/CIMP-0 CRC progression.

Application of multiplex ligation-dependent probe amplification to diagnosis and prenatal diagnosis of common aneuploidies

To investigate the application value of the multiplex ligation-dependent probe amplification (MLPA) technique in diagnosis and prenatal diagnosis of chromosomes 13, 18, 21, X and Y aneuploidy. Forty-four cases including 30 peripheral blood samples, 10 fetal cord blood samples, and 4 amniotic fluid samples were collected in this study. DNA was isolated from the samples and detected by MLPA, followed by analyzing in ABI310 Genetic Analyzer. Analysis of copy number changes for chromosomes 13, 18, 21, X and Y was carried out with RH-MLPA-analysis software. The routine karyotype analyses were also done for all the samples. Of 44 samples, the results of 42 by MLPA method was consistent with that by chromosome karyotyping. Only one case with trisomy 21 chimerism was failed to reach conclusion. In addition, one case of mark chromosome segment was identified as Y-chromosome segment by MLPA, while karyotyping failed to make judgment. The accurate rate of MLPA was 97.7% (43/44). The MLPA technique can simultaneously detect dozens of different target sequences and their copy number changes in a single reaction. It showed high specificity, good reproducibility, was fast and high-throughput. The MLPA technique can be applied to diagnosis and prenatal diagnosis of the common chromosomal aneuploidy.

Innovative technology for cancer risk analysis

After completion of the Human Genome Project, analysis of genetic and genomic variations in different pathological states became possible. The capillary system based on Sanger methods is still very expensive in terms of time, cost and professionalism required. For this reason, the National Human Genome Institute proposed an 'advanced sequencing technology development' project with the aim of sequencing a genome in 1 day for $1000. Three validated platforms are commercially available and single molecule sequencing methods have been recently introduced, which are not only competitive in time and costs, but display greater accuracy than 'past generation' sequencing. Next generation technology allows, in a single experiment, the identification of copy number variation and large rearrangements, or detection of fusion transcripts analysis thus permitting the evaluation of cancer risk at multiple levels (genomic, transcriptomic, proteomic, epigenetic).

Abstract 4728: Genome-wide analysis of genetic alterations in seminoma using high resolution single Nucleotide polymorphism (SNP) arrays

Abstract Testicular germ cell tumors (TGCT's) represent the most common malignancy among young males between the ages 15-40 years. Many genomic alterations have been observed in testicular cancer, however very few of these alterations have been associated with deregulation of gene function. The impact of CNVs on cancer susceptibility and tumor progression is only recently been explored in different cancer types. To our knowledge no comprehensive studies of testicular cancer using high-resolution SNP array have been performed, partially due to the rarity of this disease and low resolution of previous cytogenetic techniques. To identify new genomic alterations we performed a genome-wide analysis of copy-number changes and loss of heterozygosity (LOH) in 24 seminomas and validated our findings by a complementary approach. We have also confirmed the several previously reported genomic alterations in seminoma and discovered eight novel genomic alterations including amplifications and homozygous deletions. Moreover, a comparison of genomic alterations of early stage and late stage identified CNV that correlate with progression which included deletions in chromosome 4q, 5p, 9q, 13q and 20p and amplifications in chromosomes 9q and 13q. CNV aberrations for candidate genes within selected regions these regions were further validated using quantitative PCR (QPCR). 40-75% correlation was observed between CNV by SNP analysis and QPCR. In conclusion, SNP microarrays are a valuable tool to measure and identify genomic alterations in seminoma, and we identified several genomic alterations, which may help pinpoint cancer causing genes and strengthen our understanding the biology of seminoma. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4728.

Abstract 2131: Accurate quantitation of absolute allelic copy-numbers in primary solid tumor samples from SNP-array / WGS data reveals patterns of tumor progression

Abstract Genomic imbalances are a hallmark of cancer cells. Genomic regions recurrently gained or lost in many cancer samples often harbor oncogenes or tumor suppressors, making whole-genome characterization of copy-number a widely adopted strategy for the study of cancer In practice, copy-number analysis is typically performed using techniques such as array-CGH, SNP-array, or whole genome sequencing (WGS) analysis. Because a fixed quantity of DNA is extracted from a tumor sample for each of these methods, the concentration of each genomic locus is dependant on both the fraction of tumor cells and the ploidy (DNA mass) of each tumor cell. Because these quantities are generally unknown, downstream analysis of copy-number changes has been limited to consideration of relative gains/losses. Here we describe a recently developed computational method capable of accurately inferring the tumor purity, ploidy, and genome-wide absolute allelic copy-numbers from data obtained by either SNP-array (several platforms are supported), or WGS. Validation data comprised of tumor-normal cell-line mixing experiments verify the accuracy of the method. Application of these methods to large tumor-cohorts allowed for systematic re-assessment of homozygous deletion and LOH in heavily contaminated samples. These results allow for the assessment of preferential allelic deletion or amplification in genomic regions of recurrent copy loss or gain, respectively. Our data suggest that the distribution of tumor-ploidy is bi-modal for many common epithelial tumor types, with a hypo-diploid subset and a second subset of samples with ploidy ranging from three to five [haploid genomes]. The observed patterns of allelic copy-number are consistent with a model of tumor progression by which high-ploidy samples arose via whole-genome doubling from an intermediate hypo-diploid state. These analyses allow us to define characteristic “early” genomic events in several tumor types. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2131.

Patterns of Gene Expression and Copy-Number Alterations in von-Hippel Lindau Disease-Associated and Sporadic Clear Cell Carcinoma of the Kidney

Recent insights into the role of the von-Hippel Lindau (VHL) tumor suppressor gene in hereditary and sporadic clear-cell renal cell carcinoma (ccRCC) have led to new treatments for patients with metastatic ccRCC, although virtually all patients eventually succumb to the disease. We performed an integrated, genome-wide analysis of copy-number changes and gene expression profiles in 90 tumors, including both sporadic and VHL disease-associated tumors, in hopes of identifying new therapeutic targets in ccRCC. We identified 14 regions of nonrandom copy-number change, including 7 regions of amplification (1q, 2q, 5q, 7q, 8q, 12p, and 20q) and 7 regions of deletion (1p, 3p, 4q, 6q, 8p, 9p, and 14q). An analysis aimed at identifying the relevant genes revealed VHL as one of three genes in the 3p deletion peak, CDKN2A and CDKN2B as the only genes in the 9p deletion peak, and MYC as the only gene in the 8q amplification peak. An integrated analysis to identify genes in amplification peaks that are consistently overexpressed among amplified samples confirmed MYC as a potential target of 8q amplification and identified candidate oncogenes in the other regions. A comparison of genomic profiles revealed that VHL disease-associated tumors are similar to a subgroup of sporadic tumors and thus more homogeneous overall. Sporadic tumors without evidence of biallelic VHL inactivation fell into two groups: one group with genomic profiles highly dissimilar to the majority of ccRCC and a second group with genomic profiles that are much more similar to tumors with biallelic inactivation of VHL.

Genome-wide analysis of genetic alterations in Barrett's adenocarcinoma using single nucleotide polymorphism arrays

We performed genome-wide analysis of copy-number changes and loss of heterozygosity (LOH) in Barrett's esophageal adenocarcinoma by single nucleotide polymorphism (SNP) microarrays to identify associated genomic alterations. DNA from 27 esophageal adenocarcinomas and 14 matching normal tissues was subjected to SNP microarrays. The data were analyzed using dChipSNP software. Copy-number changes occurring in at least 25% of the cases and LOH occurring in at least 19% were regarded as relevant changes. As a validation, fluorescence in situ hybridization (FISH) of 8q24.21 (CMYC) and 8p23.1 (SOX7) was performed. Previously described genomic alterations in esophageal adenocarcinomas could be confirmed by SNP microarrays, such as amplification on 8q (CMYC, confirmed by FISH) and 20q13 or deletion/LOH on 3p (FHIT) and 9p (CDKN2A). Moreover, frequent gains were detected on 2p23.3, 7q11.22, 13q31.1, 14q32.31, 17q23.2 and 20q13.2 harboring several novel candidate genes. The highest copy numbers were seen on 8p23.1, the location of SOX7, which could be demonstrated to be involved in amplification by FISH. A nuclear overexpression of the transcription factor SOX7 could be detected by immunohistochemistry in two amplified tumors. Copy-number losses were seen on 18q21.32 and 20p11.21, harboring interesting candidate genes, such as CDH20 and CST4. Finally, a novel LOH region could be identified on 6p in at least 19% of the cases. In conclusion, SNP microarrays are a valuable tool to detect DNA copy-number changes and LOH at a high resolution. Using this technique, we identified several novel genes and DNA regions associated with esophageal adenocarcinoma.

Allelic Imbalance Analysis Using a Single-Nucleotide Polymorphism Microarray for the Detection of Bladder Cancer Recurrence

Non-muscle-invasive bladder cancer is a frequently occurring cancer, with an extremely high recurrence risk. Recurrence detection is based on cytology and urethrocystoscopy. A previous study suggested that a single-nucleotide polymorphism (SNP) array may be effective for noninvasive detection of allelic imbalances in urine. We investigated whether this method is suitable to detect allelic imbalance as an indicator of recurrences in non-muscle-invasive bladder cancer follow-up. DNA from blood and urine from 158 patients (113 with and 45 without recurrence) was hybridized to the Affymetrix GeneChip Mapping 10K 2.0. Allelic imbalance detection was based on SNPs showing changes from heterozygosity in blood to homozygosity in urine and on automatic analysis of copy number changes using Copy Number Analyser for GeneChip. Urine samples with tumor showed allelic imbalance at 0.4% of all informative SNPs. In samples without tumors, 0.04% of these SNPs were affected (P = 0.07). In addition, Copy Number Analyser for GeneChip analysis showed more copy number changes in samples with a tumor (P = 0.001). Losses and gains of chromosomal regions showed clustering, overlapping with known bladder cancer loci. However, 25 (22%) patients with a tumor recurrence did not display any regions with copy number changes, whereas 24 (53%) individuals without a recurrence did. Receiver operating characteristic curve analysis using the number of SNPs displaying copy number changes from the Copy Number Analyser for GeneChip analysis resulted in an area under the curve of only 0.67 (95% confidence interval, 0.58-0.76). Single-nucleotide polymorphism microarray analysis of allelic imbalance in urine cannot replace urethrocystoscopy and cytology for the detection of recurrences in non-muscle-invasive bladder cancer follow-up.

Integrated analysis of homozygous deletions, focal amplifications, and sequence alterations in breast and colorectal cancers

We have performed a genome-wide analysis of copy number changes in breast and colorectal tumors using approaches that can reliably detect homozygous deletions and amplifications. We found that the number of genes altered by major copy number changes, deletion of all copies or amplification to at least 12 copies per cell, averaged 17 per tumor. We have integrated these data with previous mutation analyses of the Reference Sequence genes in these same tumor types and have identified genes and cellular pathways affected by both copy number changes and point alterations. Pathways enriched for genetic alterations included those controlling cell adhesion, intracellular signaling, DNA topological change, and cell cycle control. These analyses provide an integrated view of copy number and sequencing alterations on a genome-wide scale and identify genes and pathways that could prove useful for cancer diagnosis and therapy.

Genome-wide analysis of copy number changes and loss of heterozygosity in myelodysplastic syndrome with del(5q) using high-density single nucleotide polymorphism arrays

We undertook a genome wide single nucleotide polymorphism analysis of a spectrum of patients with myelodysplastic syndrome del(5q) in order to investigate whether additional genomic abnormalities occur. Single nucleotide polymorphism array analysis has been shown to detect not only gene deletions but also regions of uniparental disomy that can pinpoint particular regions for mutation analysis. We studied 42 cases of myelodysplastic syndrome with del(5q), comprising 21 patients with 5q- syndrome and 21 with del(5q) (not 5q- syndrome), and 45 healthy controls by genome wide single nucleotide polymorphism analysis with the 50K Affymetrix single nucleotide polymorphism arrays. The del(5q) was characterized in all cases. The commonly deleted region of the 5q- syndrome extends between the genes SH3TC2 (proximal boundary) and GLRA1 (distal boundary) and measures 2.9 Mb. Copy number changes in addition to the del(5q) were observed in 10 of 21 patients with del(5q) myelodysplastic syndrome but in none of the patients with the 5q- syndrome. A total of 63 regions of uniparental disomy greater than 2 Mb were detected in 40 of 42 patients, dispersed on 18/23 chromosomes. In the 5q- syndrome group 31 regions of uniparental disomy were identified in 19 of 21 patients, the largest one being 7.6 Mb. All 21 patients with del(5q) myelodysplastic syndrome had uniparental disomy; in total 32 regions of uniparental disomy were identified in the 21 patients, including six regions of uniparental disomy > 10 Mb. Eight recurrent regions of uniparental disomy were observed among the 42 patients. For eight patients we had T-cell DNA as a germline control and four recurrent regions of uniparental disomy were identified that were present only in the neutrophil and not T-cell DNA. One small region of uniparental disomy at 10p12.31-p12.2 was observed in four patients with the 5q- syndrome. This study shows that regions of uniparental disomy greater than 2 Mb are found in the 5q-syndrome and del(5q) myelodysplastic syndrome, although large regions of uniparental disomy (>10 Mb) are only found in the latter group. The recurrent regions of uniparental disomy may indicate the position of novel leukemia-associated genes.

Assessment of algorithms for high throughput detection of genomic copy number variation in oligonucleotide microarray data

BackgroundGenomic deletions and duplications are important in the pathogenesis of diseases, such as cancer and mental retardation, and have recently been shown to occur frequently in unaffected individuals as polymorphisms. Affymetrix GeneChip whole genome sampling analysis (WGSA) combined with 100 K single nucleotide polymorphism (SNP) genotyping arrays is one of several microarray-based approaches that are now being used to detect such structural genomic changes. The popularity of this technology and its associated open source data format have resulted in the development of an increasing number of software packages for the analysis of copy number changes using these SNP arrays.ResultsWe evaluated four publicly available software packages for high throughput copy number analysis using synthetic and empirical 100 K SNP array data sets, the latter obtained from 107 mental retardation (MR) patients and their unaffected parents and siblings. We evaluated the software with regards to overall suitability for high-throughput 100 K SNP array data analysis, as well as effectiveness of normalization, scaling with various reference sets and feature extraction, as well as true and false positive rates of genomic copy number variant (CNV) detection.ConclusionWe observed considerable variation among the numbers and types of candidate CNVs detected by different analysis approaches, and found that multiple programs were needed to find all real aberrations in our test set. The frequency of false positive deletions was substantial, but could be greatly reduced by using the SNP genotype information to confirm loss of heterozygosity.