Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

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Expression Analysis of Gastric Cancers

ABSTRACT: Microarray Expression profiles from 58 samples comprising of 3 normals and 55 gastric cancers is used for molecular subclassification of Gastric Cancers. Data Generation and Processing: The ratiometric data here is given by Ch1(Cy3)/Ch2(Cy5) where Ch2 is Universal Reference RNA from Stratagene. Two different chips were used (13K and 18k); The ratio metric is given by (Biological sample / Universal Reference). The Biological Samples are labeled with Cy3 (Green) and the Universal Reference RNA is always labeled with Cy5 (Red). Two types of spots were excluded a) Spots for which Foreground intensity was lower from background by lesser than 10 fluoresence units. b) Spots that couldnt be identified reliably by the scanner (Arrayworx) software within the "region of interest" masked by the user. The 2 channels for each array are equalized by multiplying the reference channel Ch2(Cy5) by a constant which is derived by (Total Cy3 / Total Cy5). Subsequently, all expression ratios from each array is normalized to have median expression value = 1.

ORGANISM(S): Homo sapiens

SUBMITTER: Patrick Tan

PROVIDER: E-GEOD-2637 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:To identify Six1 target genes, we chose the mK4 cell line that represents later metanephric mesenchyme of the embryonic kidney. The cells were infected with adenovirus vectors (AxCAwt) overexpressing VP16-Six1wt or VP16-Six1W171R and cultured for 24h. Total RNA was extracted using Isogen reagent (Nippon Gene), treated with RNase-free DNase (Roche Diagnostics) and purified with RNeasy Midi Kit (QIAGEN). Poly A+ RNA was selected using Oligotex-dT30 latex beads (TaKaRa). Poly A+ RNA (20 Âµg) was reverse transcribed using an oligo(dT) primer in the presence of aminoallyl dUTP without the addition of spike-in controls. Then, single-stranded cDNAs were coupled with Cy3 (AxCAwt VP16-Six1wt infected sample) or Cy5 (AxCAwt VP16-Six1W171R infected sample) dyes, and the labeled probes were purified with QIAquick PCR Purification kit (QIAGEN). Hybridization to the microarray was carried out at 65Â°C for 17h according to the manufacturer's instruction. The arrays were washed, dried and scanned using ScanArray 5000 (GSI Lumonics) at two different PMT voltage settings (high and low) to avoid signal saturation. Cy3 and Cy5 intensities for each spot on the array were determined by QuantArray software (Version 3.0.0.0, GSI Lumonics). The raw data thus obtained was processed and the Cy3 to Cy5 ratios were calculated as follows: 1) subtraction of the fluorescence intensity of negative control spots as background from the intensity of each of the Cy3 and Cy5 spots, 2) normalization of the entire data set using the global normalization method, 3) elimination of spots with high background intensity for either dye, and 4) determination of the Cy3 to Cy5 ratios. To identify Six4 target genes, we chose the mK4 cell line that represents later metanephric mesenchyme of the embryonic kidney. The cells were infected with adenovirus vectors (AxCAwt) overexpressing VP16-Six4wt or VP16-Six4W263R and cultured for 24h. Total RNA was extracted using Isogen reagent (Nippon Gene), treated with RNase-free DNase (Roche Diagnostics) and purified with RNeasy Midi Kit (QIAGEN). Poly A+ RNA was selected using Oligotex-dT30 latex beads (TaKaRa). Poly A+ RNA (20 Âµg) was reverse transcribed using an oligo(dT) primer in the presence of aminoallyl dUTP without the addition of spike-in controls. Then, single-stranded cDNAs were coupled with Cy3 (AxCAwt VP16-Six4wt infected sample) or Cy5 (AxCAwt VP16-Six4W263R infected sample) dyes, and the labeled probes were purified with QIAquick PCR Purification kit (QIAGEN). Hybridization to the microarray was carried out at 65Â°C for 17h according to the manufacturer's instruction. The arrays were washed, dried and scanned using ScanArray 5000 (GSI Lumonics) at two different PMT voltage settings (high and low) to avoid signal saturation. Cy3 and Cy5 intensities for each spot on the array were determined by QuantArray software (Version 3.0.0.0, GSI Lumonics). The raw data thus obtained was processed and the Cy3 to Cy5 ratios were calculated as follows: 1) subtraction of the fluorescence intensity of negative control spots as background from the intensity of each of the Cy3 and Cy5 spots, 2) normalization of the entire data set using the global normalization method, 3) elimination of spots with high background intensity for either dye, and 4) determination of the Cy3 to Cy5 ratios.

Dataset Information

Expression Analysis of Gastric Cancers

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