Nuclear translocation of beta-catenin protein but absence of beta-catenin and APC mutation in gastrointestinal carcinoid tumor.
BACKGROUND
Carcinoid tumors are a group of heterogeneous tumors with neuroendocrine differentiation and are mainly located in the gastrointestinal tract. A high frequency of cytoplasmic accumulation and/or nuclear translocation of beta-catenin with frequent mutations of exon 3 of beta-catenin gene in gastrointestinal carcinoid tumor has been previously described, but the role of Wnt/beta-catenin/APC pathway in the genesis of carcinoid tumor remains largely unknown.


METHODS
To further characterize the role of Wnt/beta-catenin/APC pathway, we investigated 91 gastrointestinal carcinoid tumors and, for comparison, 26 extragastrointestinal carcinoid tumors by immunohistochemical detection of beta-catenin protein and direct sequencing of exon 3 of the beta-catenin gene and exon 15 of the APC gene.


RESULTS
Cytoplasmic accumulation and/or nuclear translocation of beta-catenin were found in 27 gastrointestinal carcinoid tumors (29.7%) but not in any extragastrointestinal carcinoid tumors. Interestingly, neither beta-catenin nor APC gene mutation was detected in all of the cases with nuclear expression of beta-catenin.


CONCLUSIONS
Our results indicate that the role beta-catenin plays in the genesis of gastrointestinal and extragastrointestinal carcinoid tumors is different. Nuclear expression of beta-catenin does not occur in extragastrointestinal carcinoid tumors, and mutation of exon 3 of beta-catenin gene and exon 15 of APC gene does not contribute to the activation of Wnt/beta-catenin/APC pathway in gastrointestinal carcinoid tumors.
Su
Min-Cheng
MC
Department of Pathology, Min-Sheng General Hospital, 168 Ching-Kuo Road, Taoyuan City, Taiwan, ROC.
Wang
Chia-Chi
CC
Chen
Chun-Chin
CC
Hu
Rey-Heng
RH
Wang
Ting-Huang
TH
Kao
Hsin-Lien
HL
Jeng
Yung-Ming
YM
Yuan
Ray-Hwang
RH
D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics* / Q000378:metabolism; D002276:Carcinoid Tumor / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D005091:Exons / Q000235:genetics; D005770:Gastrointestinal Neoplasms / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D009154:Mutation / Q000235:genetics*; D021381:Protein Transport; D013347:Subcellular Fractions; D051176:beta Catenin / Q000235:genetics* / Q000378:metabolism
D025601:Adenomatous Polyposis Coli Protein; D051176:beta Catenin