Gene expression profiling identifies potential biomarkers for colorectal cancer using NanoString nCounter assay
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ABSTRACT: The purpose of this study was to identify the differentially expressed genes and new potential predictive and prognostic molecular biomarkers for CRC. We identified 101 genes that were upregulated and 76 genes that were downregulated in metastatic tumors. After validation, a reduced set of 27 genes revealed evident correlation with CRC in the tumor tissue. Several genes in the pan-cancer panel showed significant differential expression, which were more universal than others in the CRC tissue. Since some of them have not been reported as being directly related to CRC yet, future mechanism studies can be designed based on this study.Our study demonstrated NanoString nCounter assay could serve as an alternative approach for gene expression analysis and identified several unreported differently expressed genes in CRC patients, which may provide some important clues for more in-depth study of CRC and may serve as potential predictive molecular biomarkers for clinical diagnosis application as well.
Project description:Previously, using microarrays and mRNA-Sequencing (mRNA-Seq) we found that occupational exposure to a range of benzene levels perturbed gene expression in peripheral blood mononuclear cells. In the current study, we sought to identify gene expression biomarkers predictive of benzene exposure below 1 part per million (ppm), the occupational standard in the U.S. First, we used the nCounter platform to validate altered expression of 30 genes in 33 unexposed controls and 57 subjects exposed to benzene (<1 to ≥5 ppm). Second, we used SuperLearner (SL) to identify a minimal number of genes for which altered expression could predict <1 ppm benzene exposure, in 44 subjects with a mean air benzene level of 0.55±0.248 ppm (minimum 0.203ppm). nCounter and microarray expression levels were highly correlated (coefficients >0.7, p<0.05) for 26 microarray-selected genes. nCounter and mRNA-Seq levels were poorly correlated for 4 mRNA-Seq-selected genes. Using negative binomial regression with adjustment for covariates and multiple testing, we confirmed differential expression of 23 microarray-selected genes in the entire benzene-exposed group, and 27 genes in the <1 ppm-exposed subgroup, compared with the control group. Using SL, we identified 3 pairs of genes that could predict <1 ppm benzene exposure with cross-validated AUC estimates >0.9 (p<0.0001) and were not predictive of other exposures (nickel, arsenic, smoking, stress). The predictive gene pairs are PRG2/CLEC5A, NFKBI/CLEC5A, and ACSL1/CLEC5A. They play roles in innate immunity and inflammatory responses. Using nCounter and SL, we validated the altered expression of multiple mRNAs by benzene and identified gene pairs predictive of exposure to benzene at levels below the US occupational standard of 1ppm.
Project description:The prognosis of colorectal cancer (CRC) stage II and III patients is still a challenge due to the difficulties of finding robust biomarkers and assays. The majority of published gene signatures of CRC have been generated on frozen colorectal tissues. Because collection of fresh frozen tissues is not routine and the quantity and quality of RNA derived from formalin-fixed paraffin-embedded (FFPE) tissues is vastly inferior to that derived from fresh frozen tissue, a clinical test for improving staging of colon cancer will need to be designed for FFPE tissues in order to be widely applicable. We have designed a custom Nanostring nCounter assay for quantitative assessment of expression of 414 gene elements consisting of multiple published gene signatures for colon cancer prognosis, and systematically compared the gene expression quantification between nCounter data from FFPE and Affymetrix microarray array data from matched frozen tissues using 414 genes. For microarray studies, representative sections of fresh tissue specimens were flash frozen in liquid nitrogen and stored at â80°C until RNA isolation. RNA was purified from tissue sections containing >80% epithelial tumor tissue using RNeasy (QIAGEN, Valencia, CA) according to manufacturerâs instructions. Samples were hybridized to Affymetrix arrays Human Genome U133 Plus 2.0 GeneChip Expression Arrays, Santa Clara, CA). The samples included four healthy control patient tissues, 12 stage I, 17 stage II, 20 stage III and 15 stage IV CRC patient tissues. Please note that only the *matched.csv files containing matched 414 genes' microarray and nanostring data are provided without the nanostring experimental descriptions. The matching samples between GSE62932 and the Nanostring study are indicated in the matching_samples.txt.
Project description:The prognosis of colorectal cancer (CRC) stage II and III patients is still a challenge due to the difficulties of finding robust biomarkers and assays. The majority of published gene signatures of CRC have been generated on frozen colorectal tissues. Because collection of fresh frozen tissues is not routine and the quantity and quality of RNA derived from formalin-fixed paraffin-embedded (FFPE) tissues is vastly inferior to that derived from fresh frozen tissue, a clinical test for improving staging of colon cancer will need to be designed for FFPE tissues in order to be widely applicable. We have designed a custom Nanostring nCounter assay for quantitative assessment of expression of 414 gene elements consisting of multiple published gene signatures for colon cancer prognosis, and systematically compared the gene expression quantification between nCounter data from FFPE and Affymetrix microarray array data from matched frozen tissues using 414 genes.
Project description:Nanostring nCounter Human miRNA assay (v1) of esophageal mucosal biopsies from children with eosinophilic esophagitis and controls Individual esophageal mucosal biopsies from children with eosinoniphilic esophagitis and controls were analysed for detection of microRNA
Project description:SummaryThe NanoTube is an open-source pipeline that simplifies the processing, quality control, normalization and analysis of NanoString nCounter gene expression data. It is implemented in an extensible R library, which performs a variety of gene expression analysis techniques and contains additional functions for integration with other R libraries performing advanced NanoString analysis techniques. Additionally, the NanoTube web application is available as a simple tool for researchers without programming expertise.Availability and implementationThe NanoTube R package is available on Bioconductor under the GPL-3 license (https://www.bioconductor.org/packages/NanoTube/). The R-Shiny application can be downloaded at https://github.com/calebclass/Shiny-NanoTube, or a simplified version of this application can be run on all major browsers, at https://research.butler.edu/nanotube/.Supplementary informationSupplementary data are available at Bioinformatics online.