Homo sapiens
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ABSTRACT:
PROVIDER: PRJNA139701 | 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: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:Gene expression profiling of FFPE breast cancer samples [Illumina DASL WG platform]
| PRJNA223226 | ENA
Project description:Triple negative breast tumours from archived formalin fixed paraffin embeded samples of the National Cancer Institute of Mexico were analyzed for differential gene expressión. Transcriptomic analysis of the 12 tumor samples was done with the FFPE-designed WG-DASL HT assay (Illumina) according to manufacturer’s instructions. This assay measures 29,285 annotated transcripts derived from the RefSeq database corresponding to 20,727 unique genes. Briefly, 200ng of total RNA were reverse-transcribed into biotinylated cDNA, which was then primer-extended with the Assay Specific Oligos. The cDNA was then amplified with universal primers and hybridized to Illumina Human WG DASL HT Expression BeadChip arrays. The Illumina Genome Studio V2010.2 was used to obtain the signal values (AVG-Signal), with no normalization and no background subtraction.The performance of hybridizations was evaluated by assessing the presence of outliers and the noise-to-signal ratios by calculating the ratio of centiles P95/P05 prior to normalisation for each sample. We defined outliers as samples with P95/P05 ratio <9.5. All samples were found to show a correct noise-to-signal ratio (P95/P05>9.6). For differential gene expression analysis, the public dataset GSE32124, which includes 33 fresh frozen tissue samples, generated on the Illumina HumanHT-12 v4.0 beadChip, and which contains 99.98% of the 29,285 probes of the Human WG DASL HT BeadChip was used as normal breast tissue control.
2015-05-12 | E-GEOD-62502 | 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: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:Gene expression profiling was performed on tissue samples via a complementary DNA-mediated annealing, selection, extension, and ligation (DASL) assay (Illumina). 1536 were selected for profiling. 210 prostate cancer samples were used.Random forests classifcation was applied to the DASL data, and a set of genes was selected for further development.
2013-04-01 | GSE44353 | GEO
Project description:We performed an expression profiling study of 168 primary breast tumors, lymph node metastases, and autopsy samples of primary breast tumours and metastases to liver, chest wall, lymph node, lung, and spleen, as well as positive and negative RNA controls, with technical replicates, to assess quality control methodology and probe-level reproducibility of the Illumina DASL microarray assay. The experiment included both Illumina DASL HumanRef-v3 and DASL HT-12; this series includes only the 120 HumanRef-v3 samples .
2012-10-02 | GSE32489 | GEO
Project description:We performed an expression profiling study of 168 primary breast tumors, lymph node metastases, and autopsy samples of primary breast tumours and metastases to liver, chest wall, lymph node, lung, and spleen, as well as positive and negative RNA controls, with technical replicates, to assess quality control methodology and probe-level reproducibility of the Illumina DASL microarray assay. The experiment included both Illumina DASL HumanRef-v3 and DASL HT-12; this series includes only the 48 HT12 samples .
2012-10-02 | GSE32488 | GEO
Project description:Whole-Genome Gene Expression Profiling of FFPE Tissue Samples with WG-DASL and IVT-based assays
| PRJNA123361 | ENA