Unknown,Transcriptomics,Genomics,Proteomics

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BAC CGH array profiling using Phi29-amplified colon mucosa of microdissected samples from APC and MYH mutation carriers.

ABSTRACT: Details of the series are available in the publication Cardoso J. et al., âChromosomal instability in MYH- and APC-mutant adenomatous polypsâ, Cancer Research, accepted for publication. Abstract of the publication: âThe vast majority of colorectal cancers display genetic instability, either in the chromosomal (CIN) or microsatellite (MIN) forms. While CIN tumors are per definition aneuploid, MIN colorectal cancers, caused by loss of mismatch repair function, are usually near-diploid. Recently, bi-allelic germline mutations in the MYH gene, were found to be responsible for MAP (MYH associated polyposis), an autosomal recessive predisposition to multiple colorectal polyps, often indistinguishable from the dominant FAP (familial adenomatous polyposis) syndrome caused by inherited APC mutations. Here, we analyzed MYH- and APC-mutant polyps by combining laser-capture microdissection, isothermal genomic DNA amplification, and array-CGH (comparative genomic hybridization). Smoothed quantile regression methods were applied to the MAP and FAP genomic profiles to discriminate chromosomes predominantly affected by gains and losses. Up to 80% of the MAP polyps showed aneuploid changes, which is significantly higher than the 60% found among FAP polyps. Both MAP and FAP adenomas were characterized by frequent losses at chromosome 1p, 17, 19 and 22, and gains affecting chromosome 7 and 13. The observation that aneuploidy is already detectable at early stages of MYH-driven tumorigenesis raises the possibility that CIN may contribute significantly to accelerated tumor progression, increased cancer risk, and poor prognosis in MAP.â Details of the series are available in the publication Cardoso J. et al., âChromosomal instability in MYH- and APC-mutant adenomatous polypsâ, Cancer Research, accepted for publication.

ORGANISM(S): Homo sapiens

SUBMITTER: Julian Sampson

PROVIDER: E-GEOD-3898 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Expression profiling is a well established tool for the genome-wide analysis of the transcriptional activity of human neoplasia. However, the high sensitivity of this approach combined with the well-known cellular and molecular heterogeneity of cancer often result in extremely complex and extended expression signatures of difficult functional interpretation. The majority of sporadic colorectal cancer cases are triggered by mutations in the APC tumor suppressor gene leading to constitutive activation of the Wnt/b-catenin signaling pathway and adenoma formation. Notwithstanding this common genetic basis, colorectal cancers are very heterogeneous in their degree of differentiation, growth rate and malignant potential. Here, we applied cross-species comparison of expression profiles of intestinal polyps derived from hereditary colorectal cancer patients carrying APC germline mutations, and from a mouse model carrying a targeted inactivating mutation in the mouse homologue Apc. This comparative approach resulted in the establishment of a conserved signature encompassing 166 genes differentially expressed between adenomas and normal intestinal mucosa in both species. Functional analysis of the conserved genes revealed a general increase in cell proliferation and the activation of the Wnt/b-catenin signal transduction pathway, as expected from the selection of APC/Apc-mutant intestinal adenomas. Moreover, the conserved signature is able to resolve expression profiles from hereditary polyposis patients carrying APC germline mutations from those with bi-allelic incativation of the MYH gene. Keywords: normal versus tumor comparison; compare expression profiles from microdissected samples with distinct germline mutations (FAP vs. MAP). Here, we report the expression profiles from normal and intestinal adenomatous tissue from FAP (familial adenomatous polyposis) and MAP (MUTY-associated polyposis) patients with established APC and MUTY germline mutations. Total RNA samples were obtianed by laser capture microdissection.

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BAC CGH array profiling using Phi29-amplified colon mucosa of microdissected samples from APC and MYH mutation carriers.

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