Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Transcription profiling of methotrexate-treated human colon cancer C85 cells

ABSTRACT: The experiment was aimed at identification of genes whose expression is upregulated in human colon cancer C85 cells during the process of establishment of methotrexate-induced senescence.

ORGANISM(S): Homo sapiens

SUBMITTER: Magdalena Dabrowska

PROVIDER: E-MEXP-3018 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Functional gene expression profile underlying methotrexate-induced senescence in human colon cancer cells.

Dabrowska Magdalena M Skoneczny Marek M Rode Wojciech W

Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine 20110616 5

Cellular functions accompanying establishment of premature senescence in methotrexate-treated human colon cancer C85 cells are deciphered in the present study from validated competitive expression microarray data, analyzed with the use of Ingenuity Pathways Analysis (IPA) software. The nitrosative/oxidative stress, inferred from upregulated expression of inducible nitric oxide synthase (iNOS) and mitochondrial dysfunction-associated genes, including monoamine oxidases MAOA and MAOB, β-amyloid pr ...[more]

PMID: 21678067

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Project description:We investigated the influence of genome position on propensity to amplify. First, we integrated a mutant form of DHFR into different positions in the human genome, challenged cells with methotrexate and then studied the genomic alterations arising in drug resistant cells. We observed site specific differences in methotrexate sensitivity, organization of amplicons and amplification frequency. One site was uniquely associated with a significantly enhanced propensity to amplify and recurrent amplicon boundaries, possibly implicating a rare folate sensitive fragile site in initiating amplification. Hierarchical clustering of gene expression patterns and subsequent gene enrichment analysis revealed two clusters differing significantly in expression of MYC target genes independent of integration site. We introduced a mutant form of DHFR (L22F), which confers greater resistance to methotrexate than the wild type (endogenous) gene into HCT116+chr3 cells and isolated independent clones containing DHFR* at different positions in the genome and identified genome sequences flanking the integration site of DHFR* using inverse PCR. For further analysis, we selected only clones, which were considered to have a single insertion of DHFR* by inverse PCR (13 independent insertion sites). The individual insertion site clones were further characterized with respect to genome copy number profiles. To select methotrexate resistant colonies, we exposed cells to a concentration of methotrexate that was three to four times the IC-50 for each integration site. Genomic copy number profiles were obtained for isolated resistant colonies (GSE6262) by using UCSF HumArray platform (GPL4421). Twelve methotrexate resistant colonies (four different integration sites) were selected for microarray analysis of gene expression at the mRNA level. The untreated integration site clone was used as the reference (Cy5 labeled cDNA) for each of the hybridizations with its respective resistant colonies (Cy3 labeled cDNA). Hybridizations were carried out on arrays of printed long oligonucleotides (70mers) containing 21,000 elements (Operon V2.0, printed in J. David Gladstone Institutes, Genomics Core Laboratory).

Project description:Colorectal cancer is the third most common cancer worldwide, with 1.4 million people diagnosed in 2012 according to GLOBOCAN 2012. 95% of the colon cancer cases are that of adenocarcinomas. Removal of high-risk adenomas and tumors at early stage of colorectal cancer (CRC) can prevent its onset/progression into higher grades of cancer. The prognosis of colorectal cancer and the stage of diagnosis are closely correlated. 5-year survival rate is observed among 90% patients when diagnosed early and in less than 10% when the metastases develop. This makes the implementation of screening methods aimed at early detection paramount for reduced incidence and mortality rate. Adenocarcinomas are the cancers originating from the gland forming cells of the colon and rectal lining and are known to be the most common type of colorectal cancer. The current diagnosis options for colorectal cancers are limited to biopsy, stool tests and other laboratory tests, barium enema based imaging and other imaging techniques, colonoscopy and other endoscopic procedures which are time consuming. In this study, we used proteomics approach with an aim to identify protein biomarkers which can aid in early detection of colon adenocarcinomas to be precise. Proteins from tumor tissue of colon adenocarcinoma subjects (n=11) and their matched controls were subjected to 4-plex iTRAQ labelling followed by off-gel fractionation prior to LC-MS/MS run. The mass spectrometry data was analysed independently using two different analysis software - Spectrum Mill (SM) and Trans Proteome Pipeline (TPP). The proteins identified using either SM and/or TPP were subjected to pathway analysis using the Database for Annotation, Visualization and Integrated Discovery (DAVID) v6.8 and the proteins common between the two analyses were compared with the data from CPTAC portal and Human Protein Atlas. The expression level of the shortlisted panel of proteins was studied in brain cancers as a non-colon adenocarcinoma control group and validated using MRM approach. A list of 285 unique proteins was identified to be significantly dysregulated in colon adenocarcinoma as compared to its matched controls. These proteins were found to be involved in glycolysis, pentose phosphate pathway, biosynthesis of amino acids, protein processing, spliceosome, proteosome, focal adhesion and proteoglycans in cancer. 94 of the 285 proteins were identified by both- SM and TPP. 34 of these 94 proteins were found to be dysregulated with same trend as that in data reported on CPTAC portal and 9 of these 34 proteins were validated using MRM approach. The proteins identified from this study could be validated further to investigate the role of these proteins as potential biomarkers for early detection of colon adenocarcinoma.

Dataset Information

Transcription profiling of methotrexate-treated human colon cancer C85 cells

Publications

Functional gene expression profile underlying methotrexate-induced senescence in human colon cancer cells.

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