title: [Gene expression profile of human normal gastrointestinal tract tissues: bioinformatic study].
abstract: OBJECTIVE
  To identify up-regulated genes specific to human normal gastrointestinal tissues.
  
  
  METHODS
  Study was made on human normal tissue gene expression database open to the public. Tissue-specific genes were identified using one-tailed student T test. Online software including Ingenuity and KEGG were applied for physiological function analyses. Unsupervised two-way hierarchical clustering method was used to analyze the expression profile of stomach-specific genes in gastric cancer gene expression datasets.
  
  
  RESULTS
  The analyses identified 196 stomach-specific genes, 203 ileum-specific genes and 224 colon-specific genes, respectively. The gene expression profiles reflect major organ-specific physiological functions on the molecular level. Some putative oncogenes and tumor suppressor genes were found in the tissue-specific gene list. Hierarchical clustering analysis revealed that the stomach-specific genes were up-regulated in normal stomach tissues but down-regulated in stomach cancer tissues. The normal tissues clustered together, so did the cancer tissues. At the meantime, clustering could also distinguish the moderate and severe differentiated stomach cancer.
  
  
  CONCLUSIONS
  Human normal stomach, ileum and colon possess tissue-specific up-regulated genes, which are closely associated with physiological functions.
authors.affiliation: Department of Gerontal Gastroenterology, General Hospital of Chinese PLA, Beijing 100853, China. wanggangshi@hotmail.com
authors.forename: Gang-Shi
authors.initials: GS
authors.lastname: Wang
authors.forename: Wen-Wu
authors.initials: WW
authors.lastname: Cui
authors.forename: Ben-Yan
authors.initials: BY
authors.lastname: Wu
authors.forename: Meng-Wei
authors.initials: MW
authors.lastname: Wang
mesh_terms: D016000:Cluster Analysis; D003106:Colon / Q000378:metabolism; D019295:Computational Biology; D030541:Databases, Genetic; D005753:Gastric Mucosa / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D007082:Ileum / Q000378:metabolism; D013274:Stomach Neoplasms / Q000235:genetics; D059467:Transcriptome