The different expression of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) and possible roles in gastric carcinomas

The purpose of this study was to investigate the expression of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) and its effects on promoting angiogenesis in gastric adenocarcinomas.Paraffin wax sections of 222 patients with gastric adenocarcinomas having undergone surgery between 2001 and 2006 were classified into three histotypes: intestinal, diffuse, and mixed carcinomas following the Laurén classification. Immunohistochemistry (IHC) was used to study the distribution of CEACAM1, and double-labeling immunohistochemistry was used to observe the relationship between CEACAM1 expression and neovascularization in carcinoma areas.No CEACAM1 expression was found in normal non-metaplastic mucosa adjacent to the tumors; but in metaplastic mucosa, CEACAM1 was expressed on the apical surface. However, all of the collected gastric carcinomas expressed CEACAM1 with cytoplasmic or membranous staining. CEACAM1 was expressed mainly with a membranous pattern in the intestinal carcinomas, and with a cytoplasmic pattern in the diffuse carcinomas. There was a significant difference between the expression patterns and the histotypes (P<0.0001). CEACAM1 expression was classified as high (⩾66% positive cells) and low (<66% positive cells), and high CEACAM1 expression was associated with lymph nodes metastasis (P<0.05). High microvessel density (MVD) was observed more frequently in the tumors with membranous expression, and low MVD in the tumors with cytoplasmic staining (P<0.0001).The transformation of CEACAM1 distribution from membrane to cytoplasm is an important incident for the reverse effects on the tumorous angiogenesis, and high expression of CEACAM1 facilitates the metastasis of carcinoma cells to lymph nodes. Moreover, the different distribution of CEACAM1 in the intestinal and diffuse carcinomas indicates a different tumorigenic pathway.