B -
Catenin is closely associated with
carcinoma invasion/
metastasis and poor survival. Recent studies have demonstrated that abnormal expression of B -
catenin, especially its nuclear accumulation, also plays an important role in wingless/Wnt signaling pathway. In this study, we evaluated immunohistochemically the nuclear localization of B -
catenin in a total of 93 human-endocrine-related
tumors including 1
medullary carcinoma (thyroid gland), 12 parathyroid
tumors, 22
carcinoid tumors (digestive tract and liver), 7
islet cell tumors, 26 adrenocortical
tumors, 13
neuroblastoma (adrenal gland), and 12
pheochromocytoma (adrenal gland), and also studied genetic alterations of the B -
catenin gene. Nuclear accumulation of B -
catenin was frequently detected in 8 of 22 (36%)
carcinoid tumors and 2 of 7 (29%)
islet cell tumors. No genetic alteration in exon 3 of the B -
catenin gene encoding
serine/
threonine rich domain, which was phosphorylated by
GSK-3 B, was detected in any groups of the endocrine
tumors. However, nuclear accumulation of B -
catenin in
carcinoid tumors was significantly correlated with the proliferative marker Ki-67 (MIB-1) labeling index (p <0.001). Our findings suggest that nuclear transfer and accumulation of the B -
catenin may contribute in the
tumorigenesis of
carcinoid tumor as an
oncoprotein.