Molecular characteristics of differentiated-type gastric carcinoma with distinct mucin phenotype: LI-cadherin is associated with intestinal phenotype.

Gastric carcinomas (GC) are classified into four phenotypes on the basis of the mucin expression profile: G type (gastric or foveolar phenotype), I type (intestinal phenotype), GI type (intestinal and gastric mixed phenotype) and N type (neither gastric nor intestinal phenotype). Immunohistochemistry was used to examine the expression of epidermal growth factor receptor (EGFR), E-cadherin, liver-intestine (LI)-cadherin, CD44v9 and p53 and correlation of these molecules with mucin phenotype and tumor stage was evaluated. Overexpression of EGFR and LI-cadherin, reduced expression of E-cadherin and abnormal expression of p53 were observed more frequently in advanced GC than in early GC. Among I-type GC, overexpression of EGFR and reduced expression of E-cadherin were observed more frequently in advanced tumors than in early tumors. Among G-type GC, reduced expression of E-cadherin was significantly associated with advanced tumors. With respect to the relationship between mucin phenotype and expression of cancer-related molecules, overexpression of LI-cadherin was observed more frequently in I-type (12/25, 48.0%) than in G-type (1/14, 7.1%) GC. I-type GC tended to express LI-cadherin more frequently than GI-type GC. These results provide insights into the molecular characteristics of the distinct mucin phenotype of differentiated-type GC and suggest that LI-cadherin may contribute to the biological behavior of I-type GC.