Alpha-catenin expression is decreased in patients with gastric carcinoma

To assess the expression of alpha-catenin in gastric carcinoma and to determine the role of alpha-catenin expression in gastric carcinogenesis.

alpha-catenin expression was assessed by semi-quantitative reverse transcriptase-polymerase chain reaction and immunohistochemical staining in 49 gastric carcinomas, 26 adjacent non-cancerous mucosae, and gastric biopsy specimens from 11 healthy controls.

mRNA levels of alpha-catenin were reduced or absent in 34 of 49 (69%) gastric carcinoma tissues and in 5 of 26 (19%) tumor-free gastric mucosae of carcinoma patients, respectively. Of the carcinoma samples with altered alpha-catenin mRNA levels, alpha-catenin expression was negative in 20 and decreased in 14 cases. Up to 69% of tumors were stained abnormally for alpha-catenin. Of the 34 cases whose mRNA expression of alpha-catenin was reduced, 32 (94%) showed abnormal immunostaining patterns, while only 2 showed a normal alpha-catenin expression. The frequency of reduced expression of alpha-catenin mRNA was 14% in well-differentiated carcinomas, higher than that in poorly differentiated carcinomas (86%). A significant correlation was not shown between alpha-catenin expression and both depth of invasion and lymph node metastasis. Moreover, there was no statistical difference between loss or down-regulation of alpha-catenin mRNA and Helicobacter pylori (H. pylori) infection.

Downregulation of alpha-catenin expression is common in gastric carcinoma, and alpha-catenin expression may be used as a differentiation marker. Downregulation of alpha-catenin expression may be an early event in tumorigenesis. Reduced alpha-catenin expression is not correlated with H. pylori infection.