Altered Expression of Yes-associated Protein and β-Catenin in Non-neoplastic and Neoplastic Gastric Surface Epithelia

Abstract To investigate whether differential expression of Yes-associated protein (YAP) and β-catenin is important in gastric carcinogenesis. A total of 284 paraffin-embedded samples collected from 232 patients with gastric adenocarcinoma were used to evaluate YAP and β-catenin expression by immunohistochemistry, and the experimental findings were compared against those for gastric adenocarcinoma cell lines. Nuclear YAP expression gradually increased from non-neoplastic epithelia to tubular or papillary adenocarcinomas (TPADs) and decreased in signet-ring cell carcinoma (SRCC). Cytoplasmic β-catenin expression increased from non-neoplastic epithelia to high-grade dysplasia and was decreased in TPAD and SRCC. YAP-overexpressing cell lines exhibited marked tumor cell invasion, whereas YAP-depleted cells showed reduced invasion. Nuclear YAP and cytoplasmic β-catenin play important roles in carcinogenesis, and the differential patterns YAP and β-catenin expression between TPAD and SRCC imply the existence of different carcinogenic pathways in these conditions.