ABSTRACT
<p><b>AIM</b>To identify up-regulated genes specific to human normal gastrointestinal tissues.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>Human normal stomach, ileum and colon possess tissue-specific up-regulated genes, which are closely associated with physiological functions.</p>