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Characterizing transcriptomic differences between between primary colorectal adenocarcinomas and distant metastases reveals subtypes of metastatic colorectal cancer

ABSTRACT: We present a novel approach for investigating transcriptomic differences between primary colorectal cancers (CRC) and distant CRC metastases, which may help to identify primaries at high risk for future dissemination and to inform the development of metastasis-targeted therapies. Eliminating tissue specificity of the “host” organs where tumors are located and adjusting for confounders such as exposure to chemotherapy and radiation, allows for an effective comparison of primary CRC and metastatic lesion transcriptomes at both the gene and pathway levels. Using this approach, our discovery-validation design identified that metastases are characterized by reduced epithelial-mesenchymal-transition (EMT) but increased MYC target and DNA repair pathway activities. The most significant gene-level expression differences between primaries and metastases were in FBN2 and MMP3, which showed over a 7-fold difference. In addition, we uncovered two distinct subtypes of CRC metastases that are characterized by either EMT-inflammatory or proliferative phenotypes, and demonstrated that none of the metastases examined were of consensus molecular subtype (CMS) 3 suggesting subtype exclusivity. Highlighting transcriptome differences between primary tumors and CRC metastases delineates pathways that may be activated in metastases and may assist in the development and/or selection of existing targeted treatment regimens for individuals with metastatic disease.

ORGANISM(S): Homo sapiens

PROVIDER: GSE131418 | GEO | 2019/05/18

REPOSITORIES: GEO

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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).

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Characterizing transcriptomic differences between between primary colorectal adenocarcinomas and distant metastases reveals subtypes of metastatic colorectal cancer

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