Project description:The main aim of the study was to compare genome-wide gene expression profiles obtained from the two widely used commercially available whole blood RNA collection systems - PAXgeneTM and TempusTM tubes. Comparisons of present call rates, variances, correlations and influence of globin reduction across the two collection systems was performed using in vivo glucocorticoid stimulation in 24 peripheral blood samples from three individuals. Three healthy male volunteers aged 30-35 years with body mass index of 20-25 were enrolled in the study.1.5 mg dexamethasone stimulated peripheral blood samples were drawn 3 hours later. For each sample, duplicate measures of 2.5 ml and 3ml blood was collected in PAXgeneTM tubes (PreAnalytiX GmbH, Hombrechtikon, Switzerland) and TempusTM tubes (Applied Biosystems, Foster City, CA, USA) respectively. The PAXgeneTM and TempusTM tubes were stored for 2.5 hours at room temperature and then transferred to -20°C. Due to the lower RNA yield from the PAXgeneTM tubes, RNA from two PAXgeneTM tubes was pooled together for the experiment . Total RNA was isolated from whole blood stored in PAXgeneTM and TempusTM tubes according to the respective manufacturer's instructions. The PAXgeneTM samples were processed using the PAXgeneTM Blood RNA Kit based on the Quiagen method for column purification of nucleic acids (PreAnalytiX GmbH, Hombrechtikon, Switzerland, catalogue number 762174). The TempusTM samples were isolated using the TempusTM Spin RNA Isolation Kit (Applied Biosystems, Foster City, CA, USA, catalogue number 4380204). RNA quality was assessed using an Agilent 2100 Bioanalyzer (Agilent Technologies, Palo Alto, CA, USA). The concentration and purity of total RNA was independently assessed by 260/280 UV absorption ratios, respectively (Nanophotometer, Implen, Munich, Germany). RNA samples were divided into non-globin reduced and globin reduced groups. The GLOBINclearTM-Human Kit (Ambion, Inc., Texas, USA, catalogue number #AM1980) was used to remove globin mRNA. Sample amplification and labeling for both globin-reduced and non-reduced samples was performed using the IlluminaR TotalPrep RNA Amplification Kit (Ambion, Inc., Texas, USA, catalogue number AMIL1791). RNA quality, yield and numbers of detected transcripts from the two RNA collection systems was comparable, with no significant differences between the tube types. Globin reduction resulted in a significant increase in present call rates in PAXgeneTM and TempusTM tubes and significant decrease in gene expression variance in both RNA collection tubes . Comparisons of glucocorticoid receptor-stimulated gene expression profiles between the two collection tube systems revealed an overlap of only 17 to 54%, depending on the stringency level of the statistical thresholds. This overlap increased by 1-8% when the RNA samples were processed to remove the globin mRNA. These results indicate that gene expression profiles obtained from PAXgeneTM and TempusTM differ drastically and should not be analyzed together. These data suggest that researchers must exert caution while interpreting expression profiles obtained through different RNA collection tubes.

Project description:Background: Inter-patient prostate cancer (PrCa) heterogeneity results in highly variable patient outcomes. Multi-purpose biomarkers to dissect this heterogeneity are urgently required to improve treatment and accelerate drug development in PrCa. Circulating biomarkers are most practical for evaluating this disease. We pursued the analytical validation and clinical qualification of blood mRNA expression arrays. Methods: Whole blood samples were collected into PaxGeneTM tubes from PrCa patients: 31 good prognosis patients selected for active surveillance (AS) and 63 advanced castration resistant PrCa (CRPC) patients. RNA was extracted, amplified, biotinylated, and hybridised to Affymetrix U133plus2 microarrays and analysis of genome-wide expression profiles were analysed using Bayesian Latent Process Decomposition (LPD). Findings: LPD analysis of the mRNA expression data divided the evaluable patients (n=94) into 4 separate groups. LPD1 and LPD2 consisted almost entirely of CRPC patients (14/14; 17/18); LPD3 (15/31) and LDP4 (12/21) comprised both AS and CRPC. Ten patients were unclassifiable by LPD analysis. LPD1 CRPC patients had significantly poorer overall survival (median 10.7 months, CI-95% 4.2-17.2) than CRPC patients in LPD2 to 4 (median 26.5 months, CI-95% 18.1-34.9, p=0.00007). LPD 1 membership remained the strongest prognostic factor in a multivariate analysis (HR 5.0, CI-95% 2.1-11.9, p=0.0002). Gene signatures in the poor prognosis LPD group 1 were associated with increased CD71+ early erythroid cells and decreased B-cell and T-cell immune response. A 9-gene signature, that was validated by RT-PCR studies, classified patients as group LPD 1 with a very low misclassification rate (1.2%). Interpretation: Poor PrCa outcome can be predicted using gene expression signatures from whole blood and merits further evaluation in predictive and pharmacodynamic biomarker studies for novel anticancer drugs including immune therapies. 107 blood samples were collected in paxgene tubes from 94 prostate cancer patients (31 good prognosis & 63 advanced castration resistant PrCa). Replicates include 9 biological replicates and four technical replicates

Project description:The degree to which the level of genetic variation for gene expression is shared across multiple tissues has important implications for research investigating the role of expression on the aetiology of complex human traits and diseases. In the last few years, a number of studies have been published reporting the extent of overlap in expression quantitative trait loci (eQTL) identified in multiple tissues or cell types. Whilst these studies provide important information on the regulatory control of genes across tissues, their limited power means they can typically only explain a small proportion of genetic variation for gene expression. Here, using expression data from monozygotic twins (MZ), we investigate the genetic control of gene expression in lymphoblastoid cell lines (LCL) and whole blood (WB). We estimate the genetic correlation which represents the combined effects of all causal loci across the whole genome and is a measure of the level of common genetic control of gene expression between the two RNA sources. Our results show that, when averaged across the genome, mean levels of genetic correlation for gene expression in LCL and WB samples are close to zero. We support our results with evidence from gene expression in an independent sample of LCL, T-cells and Fibroblasts. In addition, we provide evidence that housekeeping genes, which maintain basic cellular functions, are more likely to have high genetic correlations between the RNA sources than non-housekeeping gene, implying a relationship between the transcript function and the degree to which a gene has tissue specific genetic regulatory control. In this study, the global genetic control of expression levels for 9555 genes were examined from two samples of RNA sources, collected on pairs of monozygotic (MZ) twins. From each individual, gene expression profiles were generated whole blood (WB), collected using the PAXgeneTM tube system, and lymphoblastoid cell lines (LCL). Using expression data collected from MZ twins is a powerful means of estimating the genetic contribution of expression variation. In particular, the observed phenotypic covariance in gene expression in LCLs and WBs between MZ twins can be partitioned into variation due to within-person environmental effects and between-person genetic effects.

Project description:The main aim of the study was to compare genome-wide gene expression profiles obtained from the two widely used commercially available whole blood RNA collection systems - PAXgeneTM and TempusTM tubes. Comparisons of present call rates, variances, correlations and influence of globin reduction across the two collection systems was performed using in vivo glucocorticoid stimulation in 24 peripheral blood samples from three individuals. Three healthy male volunteers aged 30-35 years with body mass index of 20-25 were enrolled in the study.1.5 mg dexamethasone stimulated peripheral blood samples were drawn 3 hours later. For each sample, duplicate measures of 2.5 ml and 3ml blood was collected in PAXgeneTM tubes (PreAnalytiX GmbH, Hombrechtikon, Switzerland) and TempusTM tubes (Applied Biosystems, Foster City, CA, USA) respectively. The PAXgeneTM and TempusTM tubes were stored for 2.5 hours at room temperature and then transferred to -20°C. Due to the lower RNA yield from the PAXgeneTM tubes, RNA from two PAXgeneTM tubes was pooled together for the experiment . Total RNA was isolated from whole blood stored in PAXgeneTM and TempusTM tubes according to the respective manufacturer's instructions. The PAXgeneTM samples were processed using the PAXgeneTM Blood RNA Kit based on the Quiagen method for column purification of nucleic acids (PreAnalytiX GmbH, Hombrechtikon, Switzerland, catalogue number 762174). The TempusTM samples were isolated using the TempusTM Spin RNA Isolation Kit (Applied Biosystems, Foster City, CA, USA, catalogue number 4380204). RNA quality was assessed using an Agilent 2100 Bioanalyzer (Agilent Technologies, Palo Alto, CA, USA). The concentration and purity of total RNA was independently assessed by 260/280 UV absorption ratios, respectively (Nanophotometer, Implen, Munich, Germany). RNA samples were divided into non-globin reduced and globin reduced groups. The GLOBINclearTM-Human Kit (Ambion, Inc., Texas, USA, catalogue number #AM1980) was used to remove globin mRNA. Sample amplification and labeling for both globin-reduced and non-reduced samples was performed using the IlluminaR TotalPrep RNA Amplification Kit (Ambion, Inc., Texas, USA, catalogue number AMIL1791).

Dataset Information

Whole Blood Gene Expression Analysis of Controls and CRC Patients

Publications

Identification and validation of a blood-based 18-gene expression signature in colorectal cancer.

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