Cytoplasmic beta-catenin in esophageal cancers.
beta-Catenin has 2 distinct roles in E-cadherin-mediated cell adhesion and carcinogenesis through APC gene mutation. One occurs at cell-adhesion sites, where cadherins become linked to the actin-based cytoskeleton. The others occur in the cytoplasm and nuclei and are thought to regulate cell transformation. We studied these different beta-catenins and evaluated their significance in carcinogenesis. Fresh surgical specimens were obtained from 22 patients with squamous-cell carcinoma of the esophagus. beta-Catenin in the free soluble fraction and the insoluble fraction was immunoblotted separately. At the same time, its localization was observed by immuno-histochemical techniques. In the normal esophageal epithelium, 91% of beta-catenin was detected in the insoluble fraction and beta-catenin staining occurred at the cell membrane, in co-existence with E-cadherin. In cancerous tissues, the amount of soluble beta-catenin was significantly (about 4-fold) higher than in normal tissues. Also, in cancerous tissues with higher amounts of soluble beta-catenin, immuno-histochemical techniques revealed the presence of beta-catenin in the cytoplasm and nuclei, as well as in the cell membrane. However, in samples with lower amounts of beta-catenin, expression was found only at the cell boundaries. The amount of soluble beta-catenin was not associated with the clinico-pathological grading of the tumors. Our results show that the accumulation of free soluble beta-catenin in the cytoplasm and nuclei frequently occurs during carcinogenesis of the squamous epithelium of the esophagus.
Kimura
Y
Y
Department of Surgery II, Osaka University Medical School, Suita, Japan.
Shiozaki
H
H
Doki
Y
Y
Yamamoto
M
M
Utsunomiya
T
T
Kawanishi
K
K
Fukuchi
N
N
Inoue
M
M
Tsujinaka
T
T
Monden
M
M
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004285:Dogs; D004938:Esophageal Neoplasms / Q000378:metabolism*; D004947:Esophagus / Q000378:metabolism; D017491:Genes, APC / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D015534:Trans-Activators; D014407:Tumor Cells, Cultured; D051176:beta Catenin
C495270:CTNNB1 protein, human; D003598:Cytoskeletal Proteins; D015534:Trans-Activators; D051176:beta Catenin