Unknown,Transcriptomics,Genomics,Proteomics

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Colorectal cancer cell lines are representative models of the main molecular subtypes of primary cancer

ABSTRACT: Human colorectal cancer (CRC) cell lines are a used widely-used to model system for investigation investigate of tumour biology, experimental therapytherapeutic and biomarkers discovery. However, to what extent these established CRC cell lines represent and maintain the genetic diversity of primary cancers is uncertain. In this study, we analyzed 70 CRC cell lines were analysed for mutations using whole exome sequencing and DNA copy-number using by whole-exome sequencing and SNP microarray profilings, respectively. Presence of gGene expression was defined using RNA-Seq. Data from cellCell line datas were was compared to those that published from for primary CRCs published by in The the Cancer Genome Atlas Network. Notably, we found that The spectrum of exome mutations and DNA copy-number aberrations spectra in 70 CRC cell lines closely resembled those seen inat of primary colorectal tumours. Similarities included the presence of at least two hypermutation phenotypes, as defined by signatures of for defective DNA mismatch repair and DNA polymerase ? (POLE) proof-reading deficiency, and along with concordant mutation profiles in the broadly altered WNT, MAPK, PI3K, TGF? and p53 pathways. In additionFurther, we documented mutations were enriched in genes involved in chromatin remodelling (ARID1A, CHD6, SRCAP) and histone methylation or acetylation (ASH1L, EP300, EP400, MLL2, MLL3, PRDM2, TRRAP). Chromosomal instability was prevalent in non-hypermutated cases, with similar patterns of whole, partial and focal chromosomal aberrations and overlapping significant minimal regions ofchromosomal gains and losses. While paired cell lines derived from the same tumour were found to exhibited considerable mutation and DNA copy-number differences, in silico simulations suggest that these differenceslargely mainly reflected a pre-existing heterogeneity in the tumour cells heterogeneity. In conclusion, our results establish that human CRC lines are representative of the main subtypes of primary tumours at the genomic level, further validating underscoring their utility as tools for to investigating investigate CRC biology and drug responses. 69 colorectal cancer cell lines were analysed for DNA copy number profiles.

ORGANISM(S): Homo sapiens

SUBMITTER: Oliver Sieber

PROVIDER: E-GEOD-55832 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Human colorectal cancer (CRC) cell lines are a used widely-used to model system for investigation investigate of tumour biology, experimental therapytherapeutic and biomarkers discovery. However, to what extent these established CRC cell lines represent and maintain the genetic diversity of primary cancers is uncertain. In this study, we analyzed 70 CRC cell lines were analysed for mutations using whole exome sequencing and DNA copy-number using by whole-exome sequencing and SNP microarray profilings, respectively. Presence of gGene expression was defined using RNA-Seq. Data from cellCell line datas were was compared to those that published from for primary CRCs published by in The the Cancer Genome Atlas Network. Notably, we found that The spectrum of exome mutations and DNA copy-number aberrations spectra in 70 CRC cell lines closely resembled those seen inat of primary colorectal tumours. Similarities included the presence of at least two hypermutation phenotypes, as defined by signatures of for defective DNA mismatch repair and DNA polymerase ε (POLE) proof-reading deficiency, and along with concordant mutation profiles in the broadly altered WNT, MAPK, PI3K, TGFβ and p53 pathways. In additionFurther, we documented mutations were enriched in genes involved in chromatin remodelling (ARID1A, CHD6, SRCAP) and histone methylation or acetylation (ASH1L, EP300, EP400, MLL2, MLL3, PRDM2, TRRAP). Chromosomal instability was prevalent in non-hypermutated cases, with similar patterns of whole, partial and focal chromosomal aberrations and overlapping significant minimal regions ofchromosomal gains and losses. While paired cell lines derived from the same tumour were found to exhibited considerable mutation and DNA copy-number differences, in silico simulations suggest that these differenceslargely mainly reflected a pre-existing heterogeneity in the tumour cells heterogeneity. In conclusion, our results establish that human CRC lines are representative of the main subtypes of primary tumours at the genomic level, further validating underscoring their utility as tools for to investigating investigate CRC biology and drug responses.

Project description:In colorectal cancer (CRC), chromosomal instability (CIN) is typically studied using comparative-genomic hybridization (CGH) arrays. We studied paired (tumor and surrounding healthy) fresh-frozen tissue from 86 CRC patients using Illumina’s Infinium-based SNP array. This method allowed us to study CIN in CRC, with simultaneous analysis of copy number (CN) and B-allele frequency (BAF), which is a representation of allelic composition. This data helped us to detect mono-allelic and bi-allelic amplifications/deletion, copy neutral loss of heterozygosity, and levels of mosaicism for mixed cell populations, some of which can not be assessed with other methods that do not measure BAF. We identified associations between CN abnormalities and different CRC phenotypes (MSI, histological diagnosis, location, tumor grade, stage, MSI and presence of lymph node metastasis). We showed commonalities between regions of CN change observed in CRC and the regions reported in previous studies of other solid cancers (e.g., amplifications of 20q, 13q, 8q, 5p and deletions of 18q, 17p and 8p). From the Therapeutic Target Database we found relevant drugs, targeted to the genes located in these regions with CN changes, approved or in trials for other cancers and common diseases. These drugs may be considered for future therapeutic trials in CRC, based on personalized cytogenetic diagnosis. We also found many regions harboring genes which are not currently targeted by any relevant drugs that may be considered for future drug discovery studies. Our study shows the application of high-density SNP arrays for cytogenetic study in CRC and its importance for personalized treatment. DNA was extracted from colon tissue samples provided by 86 CRC patients. Each patient provided paired CRC tumor tissue and adjacent normal colon mucosa samples, which were fresh-frozen after resection. Samples were genotyped using Illumina's Infinium-based 610 Quad and CytoSNP 12 microarray chips. The genotype data from paired tumor and normal samples was used to detect tumor-specific chromosomal instabilities in copy number, including copy-neutral LOH, which cannot be assessed by many other cytogenetic methods. Supplementary file "GSE34678_raw_GPL8887.txt" includes the raw data for Samples using GPL8887 (GSM853162-GSM853239); supplementary file "GSE34678_raw_GPL13829.txt" includes the raw data for Samples using GPL13829 (GSM853240-GSM853363).

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:Background: Liver metastasis is the major cause of death following a diagnosis of colorectal cancer (CRC) and is a major health burden. Most molecular studies of CRC have profiled primary tumor samples and not the metastasis samples. In this study, we compared the copy number profiles of matched primary and liver metastatic CRC to better understand how the genomic structure of primary CRC differs from the metastasis. This has important implications for whether it is justified to base therapeutic approaches solely on data from the primary tumour. Methods: Paired primary and metastatic tumours from 16 patients and their adjacent normal tissue samples were analyzed using Single-Nucleotide-Polymorphism (SNP) arrays to determine copy number alterations. Nine patients had a synchronous liver metastasis at the time of CRC diagnosis and 7 patients developed a liver metastasis metachronously. Genome-wide chromosomal copy number alterations were assessed, with particular attention to 189 genes known to be somatically altered in CRC and 25 genes that are clinically actionable in CRC. These data were analyzed with respect to the timing of primary and metastatic tissue resection and with exposure to chemotherapy. Results: The genomic divergence with the whole genome duplication correction applied the average percent copy number discordance across all pairs of samples was 22.02%. The pairs of tumour samples collected prior to treatment revealed a significantly higher copy number differences compared to previously treated liver metastasis samples (P=0.024). However, loss of heterozygosity (LOH) acquired in metastasis was significantly higher in previously treated liver metastasis samples compared to treatment naïve liver metastasis samples (P= 0.0064) and which included where KRAS mutation was present in the primary cancers but was not detectable in the metastatic sample following chemotherapy. With regard to 25 genes that are clinically actionable in CRC, amplification of the genes ERBB2, FGFR1, CDK8 or PIK3CA was observed in the metastatic tissue of 4 patients but not in the matched primary CRC. In these cases, knowledge of these metastatic specific alterations could have informed therapeutic decision making and may have improved patient outcome. Conclusion: Intra-patient genomic discrepancies observed between primary and metastatic tissue

Project description:Background: In vitro models are an essential tool towards understanding the molecular characteristics of colorectal cancer (CRC) and the testing of therapies for CRC. To this end we established 21 novel CRC cell lines of which six were derived from liver metastases. Extensive genetic, genomic, transcriptomic and methylomic profiling was performed in order to characterize these new cell lines and all data is made publically available. Additionally, sensitivity of oxaliplatin was tested as a measure for chemotherapy resistance. Results: DNA copy-number alterations (CNA) were compared between primary and metastasis derived cell lines. In concordance with previous studies copy-number gain of chr20, and loss of chr8p were found highly specific for liver metastases. Previously reported BRAF-mutation associated DNA methylation profiles could be validated on the genome-wide DNA methylation profiles of these cell lines. 47.6% of the loci previously reported to associate with BRAF mutation status were reproduced in this dataset. When examining the gene expression profiles in conjunction with these DNA methylation results, we identified 20 genes of which the gene expression correlated with the DNA methylation status, including MEIS1, LRAT and STC2. These genes have previously been reported to be subject to transcriptional regulation through DNA hypermethylation, validating our approach. Conclusions: By combining mutation profiles with CNA and gene expression profiles we constructed an overview of the alterations in the major CRC-related signalling pathways. The mutation profiles, along with the genome, transcriptome and methylome data of these cell lines will be made publically available . This combined dataset puts these cell lines among the best characterized CRC cell lines, allowing researchers to select appropriate cell line models for their particular experiment, making optimal use of these novel cell lines as in vitro model for CRC. 21 CRC cell lines were analyzed

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Colorectal cancer cell lines are representative models of the main molecular subtypes of primary cancer

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