Dataset Information

CytoScanHD array Data for 15 normal, 15 primary colorectal carcinomas and their 15 matched liver metastases

ABSTRACT: We performed whole exome sequencing and copy number analysis for 15 triplets, each comprising normal colorectal tissue, primary colorectal carcinoma, and its synchronous matched liver metastasis. We analyzed the similarities and differences between primary colorectal carcinoma and matched liver metastases in regards to somatic mutations and somatic copy number alterationss (SCNAs). The genomic profiling demonstrated mutations in APC(73%), KRAS (33%), ARID1A and PIK3CA (6.7%) genes between primary colorectal and metastatic liver tumors. TP53 mutation was observed in 47% of the primary samples and 67% in liver metastatic samples. The grouped pairs, in hierarchical clustering showed similar SCNA patterns, in contrast to the ungrouped pairs. Many mutations (including those of known key cancer driver genes) were shared in the grouped pairs. The ungrouped pairs exhibited distinct mutation patterns with no shared mutations in key driver genes. Four ungrouped liver metastasis samples had mutations in DNA mismatch repair genes along with hypermutations and a substantial number of copy number of alterations. Genomically, colorectal and metastatic liver tumors were very similar. However, in a subgroup of patients, there were genetic variations in liver metastases in the loss of DNA mismatch repair genes.

ORGANISM(S): Homo sapiens

PROVIDER: GSE53799 | GEO | 2014/03/01

SECONDARY ACCESSION(S): PRJNA233312

REPOSITORIES: GEO

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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 & 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: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.

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CytoScanHD array Data for 15 normal, 15 primary colorectal carcinomas and their 15 matched liver metastases

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