title: Significance of increased apoptosis and Bax expression in human small intestinal adenocarcinoma.
abstract: Human small intestine accounts for 75% of the gastrointestinal (GI) length but for only 1-5% of GI tumors. The reason remains as yet unclearly understood. Our study was designed to examine whether increased apoptosis and expression of related genes/proteins, especially those of the Bcl-2 family, contribute to this difference. For this purpose, 77 samples from patients were examined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and immunohistochemistry, including 40 cases from normal small intestine (jejunum), 7 cases from jejunum and ileum adenocarcinomas, and 30 cases from normal colon. The results showed that a significantly higher level of enterocyte apoptosis was observed in normal small intestine compared with small intestinal adenocarcinomas and normal colon (median of apoptotic index, 15.2% vs 0.1% and 1.6%, p<0.01). A similar pattern was observed for Bax (expression-positive, 77.5% vs 28.6% and 53.3%, p<0.05) but not for Bcl-2 (42.5% vs 42.9% and 46.7%, p>0.05) or Bax/Bcl-2 ratio (percent of samples having a ratio > or =1, 45.0% vs 14.3% and 36.7%, p>0.05). In conclusion, increased apoptosis and expression of Bax, not Bcl-2 or the Bax/Bcl-2 ratio, may play some role in the relatively lower incidence of human small intestinal carcinomas. However, more studies are required for a better understanding of these changes.
authors.affiliation: Department of Gastroenterology, Peking University Third Hospital, Beijing, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Gao
authors.forename: Ai-Ying
authors.initials: AY
authors.lastname: Wang
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D017209:Apoptosis; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007414:Intestinal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism* / Q000473:pathology*; D008297:Male; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
chemical_list: D051028:bcl-2-Associated X Protein