Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

A new classification of chromosome instability (CIN) phynotype, CIN-high and CIN-low (validation dataset)

ABSTRACT: Samples were taken from colorectal cancers in surgically resected specimens in 33 colorectal cancer patients. The expression profiles were determined using Affymetrix Human Genome U133 Plus 2.0 arrays. Comparison between the sample groups allow to identify a set of discriminating genes that can be used for molecular markers for CIN phynotype Specimens from 33 consecutive stage II and stage III patients who had undergone surgical resection of CRC were studied. Patients with familial adenomatous polyposis and HNPCC were excluded from the study. Specimens from tumors and corresponding normal tissues in surgically resected specimens were snap-frozen in liquid nitrogen and stored at -80degreesC until use. Parallel tumor specimens were formalin fixed and paraffin embedded for histological examination. DNA and RNA was extracted from paired tumor and normal tissue using frozen samples. The patients provided written, informed consent to the collection of specimens, and the local Ethics Committee approved the study protocol. MSI and LOH phenotype analysis were done as follows; Using DNA, we performed the polymerase chain reaction (PCR) and determined the MSI status. In addition to five microsatellite markers recommended by the National Cancer Institute workshop, we also used TP53, D18S46, D18S363 and D18S474.9 We determined LOH status in non–MSI-high tumors, because LOH is rare in MSI-high tumors and also interpretation of LOH is difficult in MSI-high tumors. We defined LOH at each locus as a 50% reduction in the height of one of two allele peaks in tumor DNA relative to non-neoplastic control DNA. LOH was defined as present if any of the markers on the same chromosome show LOH. In order to evaluate the severity of chromosomal instability based on the actual frequency of LOH among evaluable loci, we defined the LOH Ratio (%) as: LOH Ratio (%) = Total number of chromosomes with LOH / Total number of chromosomes that could be evaluated for LOH × 100. Depending on the LOH Ratio, we classified tumors as having high levels of chromosomal instability (CIN-high) (33% < LOH Ratio < 100%) or low levels of chromosomal instability (CIN-low) (0% < LOH Ratio <33%). Furthermore, CIN-high tumors were divided into two subgroups; CIN-high (mild type) (33% < LOH Ratio < 75%) and CIN-high (severe type) (75% < LOH Ratio <100%).

ORGANISM(S): Homo sapiens

SUBMITTER: Toshiaki Watanabe

PROVIDER: E-GEOD-34489 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

ACCESS DATA

Similar Datasets

Project description:Samples were taken from colorectal cancers in surgically resected specimens in 35 colorectal cancer patients. The expression profiles were determined using Affymetrix Human Genome U133 Plus 2.0 arrays. Comparison between the sample groups allow to identify a set of discriminating genes that can be used for molecular markers for CIN phynotype. Specimens from 35 consecutive stage II and stage III patients who had undergone surgical resection of CRC were studied. Patients with familial adenomatous polyposis and HNPCC were excluded from the study. Specimens from tumors and corresponding normal tissues in surgically resected specimens were snap-frozen in liquid nitrogen and stored at -80 ºC until use. Parallel tumor specimens were formalin fixed and paraffin embedded for histological examination. DNA and RNA was extracted from paired tumor and normal tissue using frozen samples. The patients provided written, informed consent to the collection of specimens, and the local Ethics Committee approved the study protocol. MSI and LOH phenotype analysis were done as follows; Using DNA, we performed the polymerase chain reaction (PCR) and determined the MSI status. In addition to five microsatellite markers recommended by the National Cancer Institute workshop, we also used TP53, D18S46, D18S363 and D18S474.9 We determined LOH status in non–MSI-high tumors, because LOH is rare in MSI-high tumors and also interpretation of LOH is difficult in MSI-high tumors. We defined LOH at each locus as a 50% reduction in the height of one of two allele peaks in tumor DNA relative to non-neoplastic control DNA. LOH was defined as present if any of the markers on the same chromosome show LOH. In order to evaluate the severity of chromosomal instability based on the actual frequency of LOH among evaluable loci, we defined the LOH Ratio (%) as: LOH Ratio (%) = Total number of chromosomes with LOH / Total number of chromosomes that could be evaluated for LOH × 100. Depending on the LOH Ratio, we classified tumors as having high levels of chromosomal instability (CIN-high) (33% < LOH Ratio < 100%) or low levels of chromosomal instability (CIN-low) (0% < LOH Ratio <33%). Furthermore, CIN-high tumors were divided into two subgroups; CIN-high (mild type) (33% < LOH Ratio < 75%) and CIN-high (severe type) (75% < LOH Ratio <100%).

Project description:Colorectal cancer, one of the most frequent types of malignancy in the Western world, develops through a multi-step process. The main pathways establishing transformation of normal mucosa to invasive carcinoma include chromosomal instability (CIN), microsatellite instability (MSI) or epigenetic silencing through the CpG Island Methylator Phenotype (CIMP). These pathways have distinct clinical, pathological and genetic characteristics. In general, altered cell surface glycosylation has been linked to colorectal cancer progression, however the impact of MSI-specific pathways on the glycosylation machinery of MSI colon cancer cells has not been investigated yet. In a recent study (Patsos et al., 2009) we have shown that MSI-specific mutations induce marked alterations in cell surface glycosylation, indicating specific changes in the expression of glyco-genes. Therefore the purpose of our experiment is to define these changes by glyco-gene chip analysis. Biallelic mutational inactivation of MSI target genes is believed to drive MSI tumorigenesis. TGFBR2, ACVR2 and AIM2 are among the most frequently mutated genes in MSI colorectal adenomas and carcinomas and functional studies indicate their contribution to MSI-carcinogenesis. A first general screening approach by lectin FACS analysis indicated a correlation between functional inactivation of these genes and cell surface glycosylation of the MSI colon cell line HCT116 (Patsos et al., 2009). For detailed analysis of the altered glycosylation pattern and the underlying molecular mechanisms we have established HCT116 double stable transfectants that allow doxycycline-inducible expression of the three MSI target genes TGFBR2, ACVR2 and AIM2 in a reversible manner. Thus we can experimentally control the expression of the MSI-genes and analyze short and long-term effects on different cell functions, including glycosylation. From the application of the glyco-gene chip for analysis of the transfectants we expect to gain seminal information on the influence of MSI-target genes on glycan expression and function in MSI tumor cells. Correlating loss-of-function of MSI target genes not yet linked with glycosylation to the regulation of the glycophenotype is a novel approach to investigate the glycobiology of tumor cells. In addition it is also suitable to detect new MSI-(glyco)markers for clinical applications, including diagnostic tumor markers and specific targets for immunotherapies.

Dataset Information

A new classification of chromosome instability (CIN) phynotype, CIN-high and CIN-low (validation dataset)

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets