Unknown,Transcriptomics,Genomics,Proteomics

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Transcription profiling of human gastric tumors and adjacent non-cancerous mucosa compared to gastric mucosa in healthy individuals

ABSTRACT: Gastric Carcinoma is a very serious condition. Tumors are often not detected until late, and 5-year survival rates are 20%. Early diagnosis or prediction of gastric cancer is of outmost importance. Molecularly, those tumours are not well characterized.

Aim: by use of cDNA microarray to do a three-way comparison of gene expression patterns between tumour (T), flat (non-cancerous) mucosa (N) from stomachs with carcinoma, and normal mucosa in matched controls (K). Our first goal was to look at genes commonly differentially expressed between TvsN and TvsK (both criteria fulfilled) and NvsK.

Subjects and methods: We analyzed gene expression in tumor and flat mucosa biopsies from seven patients with gastric carcinoma and in age/sex matched samples from healthy individuals. Total RNA was extracted and samples (2 ug total RNA) were labeled for cDNA microarray analysis using Genisphere's 3DNA dendrimer kit. The gene expression patterns for 12759 genes were analyzed.

INSTRUMENT(S): ScanArray Express HT [PerkinElmer]

ORGANISM(S): Homo sapiens

DISEASE(S): normal

SUBMITTER: Kristin Nørsett

PROVIDER: E-MEXP-1164 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Colorectal cancer (CRC) is a genetically heterogeneous disease with several distinct morphological growth patterns. This study was aimed to investigate genes differentially expressed between ulcerative and polypoid colorectal CRC. cDNA microarray was first employed to compare the gene expression profiling of ulcerative and polypoid CRC with paired normal mucosa. Potential candidates identified by data filtering were further validated using quantitative real-time polymerase chain reaction, western blot and immunohistochemistry. Epigenetic regulation of gene expression was investigated using methylation-specific PCR (MSP). cDNA microarray identified 11 up-regulated and 14 down-regulated genes differentially expressed in both types of tumor compared to matched normal mucosa. Among them, S100P was the only upregulated gene preferentially associated with polypoid CRC (p = 0.032), whereas no genes demonstrated significantly differential association with ulcerative CRC. S100P protein and mRNA expression level of polypoid CRC was significantly higher than that of ulcerative CRC (p < 0.05, respectively). Immunoreactivity of S100P protein was localized predominantly in the nuclei and to a less extent in the cytoplasm. Overexpression of S100P occurred early in the adenoma stage. 80% (24/30) and 20% (6/30) polypoid CRC showed diffusely strong and moderate overexpression, respectively. In contrast, S100P was diffusely and strongly expressed in 15% (6/40) ulcerative CRC, with 52.5% (21/40) and 32.5% (13/40) tumors having moderate and weak overexpression, respectively. S100P overexpression was preferentially associated with polypoid CRC (p < 0.001). The relative methylation level determined by MSP was not statistically different between polypoid and ulcerative CRC (43.36% vs. 49.10%, p = 0.168), indicating that promoter hypomethylation was directly related to upregulation of S100P mRNA. The gene expression profiling of ulcerative and polypoid CRC with paired normal mucosa were compared. Dye swapping experiments with ulcerative CRC vs normal mucosa or polypoid CRC vs normal mucosa were performed and we averaged the log ratios of the duplicated spots on each slide.

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Transcription profiling of human gastric tumors and adjacent non-cancerous mucosa compared to gastric mucosa in healthy individuals

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