Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA123361 | ENA |
REPOSITORIES: ENA
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Project description:Microarray-based gene expression analysis of peripheral whole blood is a common strategy in the development of clinically relevant biomarker panels for a variety of human diseases. However, the results of such an analysis are often plagued by decreased sensitivity and reliability due to the effects of relatively high levels of globin mRNA in whole blood. Globin reduction assays have been shown to overcome such effects, but they require large amounts of total RNA and may induce distinct gene expression profiles. The Illumina whole-genome DASL (WG-DASL) assay can detect gene expression levels using partially degraded RNA samples and has the potential to detect rare transcripts present in highly heterogeneous whole blood samples without the need for globin reduction. We therefore assessed the utility of the WG-DASL assay in the analysis of peripheral whole blood gene expression profiles. We find that gene expression detection is significantly increased with the use of WG-DASL compared to the standard in vitro transcription-based direct hybridization (IVT), while globin-probe-negative WG-DASL did not exhibit significant improvements over globin-probe-positive WG-DASL. Globin reduction increases the detection sensitivity and reliability of both WG-DASL and IVT with little effect on raw intensity correlations: raw intensity correlations between total RNA and globin-reduced RNA were 0.970 for IVT and 0.981 for WG-DASL. Overall, the detection sensitivity of the WG-DASL assay is higher than the IVT-based direct hybridization assay, with or without globin reduction, and should be considered in conjunction with globin reduction methods for future blood-based gene expression studies.
2011-04-01 | GSE28064 | GEO
Project description:Cross-platform comparison between WG-DASL and IVT-based assays
2010-01-13 | GSE17575 | GEO
Project description:Microarray-based gene expression analysis of peripheral whole blood is a common strategy in the development of clinically relevant biomarker panels for a variety of human diseases. However, the results of such an analysis are often plagued by decreased sensitivity and reliability due to the effects of relatively high levels of globin mRNA in whole blood. Globin reduction assays have been shown to overcome such effects, but they require large amounts of total RNA and may induce distinct gene expression profiles. The Illumina whole-genome DASL (WG-DASL) assay can detect gene expression levels using partially degraded RNA samples and has the potential to detect rare transcripts present in highly heterogeneous whole blood samples without the need for globin reduction. We therefore assessed the utility of the WG-DASL assay in the analysis of peripheral whole blood gene expression profiles. We find that gene expression detection is significantly increased with the use of WG-DASL compared to the standard in vitro transcription-based direct hybridization (IVT), while globin-probe-negative WG-DASL did not exhibit significant improvements over globin-probe-positive WG-DASL. Globin reduction increases the detection sensitivity and reliability of both WG-DASL and IVT with little effect on raw intensity correlations: raw intensity correlations between total RNA and globin-reduced RNA were 0.970 for IVT and 0.981 for WG-DASL. Overall, the detection sensitivity of the WG-DASL assay is higher than the IVT-based direct hybridization assay, with or without globin reduction, and should be considered in conjunction with globin reduction methods for future blood-based gene expression studies. Peripheral whole blood samples were collected from eight human donors in PAXGene tubes. RNA was isolated after freezing and storage, and then prepared for gene expression analysis using the Illumina Human-Ref8 v3.0 BeadChip. Alpha and beta globin were reduced from a portion of the total RNA using the GLOBINclear assay (Ambion, Austin, TX, USA). Two methods of microarray target preparation were examined: Illumina IVT-based direct hybridization (IVT) and Illumina Whole-Genome DASL (WG-DASL). Two DASL Assay Oligo pools (DAP) were utilized for DASL target preparation: the DASL Assay Oligo Pool with globin probes (DAP +) and the DASL Asssay Oligo Pool without globin probes (DAP-).
2011-04-01 | E-GEOD-28064 | biostudies-arrayexpress
Project description:The use of Affymetrix U133 2.0 Plus chips on FFPE samples when coupled with a qPCR-based sample pre-assessment step, yielded satisfactory results from the point of view of biological reliability. When compared with the Illumina DASL WG platform, specifically designed for degraded RNA, the data generated with the Affymetrix platform showed a wider interquartile range (1.32 vs 0.57, p<2.2x10-16) suggesting a superior discriminatory power within samples as indicated by the good agreement with the immunohistiochemically derived ER status. FFPE primary breast cancer samples profiled using Illumina DASL WG platform after RNA amplification with the Nugen WT-Ovation FFPE System
2015-02-25 | GSE51451 | GEO
Project description:Comparison between in vitro transcription- and cDNA-mediated annealing, selection and ligation (DASL)-based assays on brain-specific reference RNA, and postmortem frozen and formalin fixed brain tissue from autistic and control cases. Investigation of data preprocessing techniques for DASL-assayed RNA samples from frozen brain tissue. IVT- and DASL-based expression assays were performed on 10 reference RNA samples (brain and pooled artificially degraded at 0, 10, 30, and 60 min), 4 formalin-fixed tissue-extracted RNA samples with replicates, and 57 frozen tissue-extracted RNA samples with replicates. A subset of the 57 (N=33 samples) from frozen brain tissue assayed using the DASL-based platform were then used to test different dataset preprocessing strategies implemented in the lumi package in R/Bioconductor. The data from frozen-tissue extracted DASL-processed RNA samples passing exclusion criteria were log2 transformed and normalized using quantile normalisation with lumi in R (quantile-normalized data available as a supplementary file linked to the Series record).
2012-04-02 | E-GEOD-28475 | biostudies-arrayexpress
Project description:Gene expression profiling of FFPE breast cancer samples [Illumina DASL WG platform]
| PRJNA223226 | ENA
Project description:The use of Affymetrix U133 2.0 Plus chips on FFPE samples when coupled with a qPCR-based sample pre-assessment step, yielded satisfactory results from the point of view of biological reliability. When compared with the Illumina DASL WG platform, specifically designed for degraded RNA, the data generated with the Affymetrix platform showed a wider interquartile range (1.32 vs 0.57, p<2.2x10-16) suggesting a superior discriminatory power within samples as indicated by the good agreement with the immunohistiochemically derived ER status. FFPE primary breast cancer samples profiled using Illumina DASL WG platform after RNA amplification with the Nugen WT-Ovation FFPE System The following criteria were considered for a direct comparison of 12 GEPs obtained from Affymetrix and DASL platforms: gene variability as defined by IQR, ESR1 expression in ER status subgroups defined by IHC, distribution of fold changes for predefined ER related genes when comparing ER positive and negative samples.
2015-02-25 | E-GEOD-51451 | biostudies-arrayexpress
Project description:Over 20 million archival tissue samples are stored annually in the United States as formalin-fixed, paraffin-embedded (FFPE) tissue blocks, but only recently has whole-genome expression profiling from these samples become technically feasible. Here, we introduce novel general methods for assessing, summarizing, and visualizing expression data quality from archival samples. We validated these methods in technical study of 144 clinical breast cancer and autopsy samples and in an overview of all current publicly available FFPE whole-genome expression data. We additionally performed a case study incorporating over 1,000 colorectal cancer (CRC) samples collected from patients across the United States over a period of more than 25 years, integrating clinicopathological information, tumor molecular data, and archival tissue gene expression on an unparalleled scale. Both large-scale clinical studies presented a much greater range of data quality than previous smaller studies, emphasizing the need for rigorous quality control in translational applications of archival tissue gene expression profiling. This series includes 1,003 FFPE-preserved CRC tumors, assayed by Illumina HumanRef-v3 WG-DASL microarray.
2012-10-02 | E-GEOD-32651 | biostudies-arrayexpress
Project description:Tissue sample acquisition is a limiting step in many studies. There are many thousands of formalin fixed paraffin embedded archival blocks collected around the world, but in contrast relatively few fresh frozen samples in tumor banks. Once samples are fixed in formalin the RNA is degraded and traditional methods for gene expression profiling are not suitable. In this study we have evaluated the whole genome DASL assay from Illumina to perform transcriptomic analysis from archived breast tumor tissue fixed in formalin paraffin embedded blocks. We profiled 76 familial breast tumors from cases carrying a BRCA1, BRCA2 or ATM mutation, or from non-BRCA1/2 families. We found that replicate samples correlated well with each other (r2=0.9-0.98). In 12/15 cases, the matched formalin-fixed and frozen samples predicted the same tumor molecular subtypes with confidence. These results demonstrate that the whole genome DASL assay is a valuable tool to profile degraded RNA from archival FFPE material. This assay will enable transcriptomic analysis of a large number of archival samples that are stored in pathology archives around the globe and consequently will have the potential to improve our understanding and characterisation of many diseases. RNA was extracted from FFPE Familial breast tumours and analysed using the WG-DASL assay for Illumina.
2010-06-16 | E-GEOD-21921 | biostudies-arrayexpress
Project description:The use of Affymetrix U133 2.0 Plus chips on FFPE samples when coupled with a qPCR-based sample pre-assessment step, yielded satisfactory results from the point of view of biological reliability. When compared with the Illumina DASL WG platform, specifically designed for degraded RNA, the data generated with the Affymetrix platform showed a wider interquartile range (IQR 1.32 vs 0.57, p<2.2x10-16) suggesting a superior discriminatory power within samples as indicated by the good agreement with the immunohistiochemically derived ER status.
2015-02-25 | GSE51450 | GEO