Expression of Gal beta 1-4GlcNAc sequences by human gastrointestinal neoplasms and their precursors as detected by Erythrina cristagalli and Erythrina corallodendron lectins

Abstract

Lectins from Erythrina cristagalli (EGA) and Erythrina corallodendron (ECorA) are well-known to detect type 2 chain oligosaccharides (Gal beta 1-4GlcNAc). These carbohydrate moieties are the biosynthetic precursors of various ABH and Lewis blood group antigens and are therefore also related to tumor-associated carbohydrate antigens. For this reason, we investigated the expression of ECA and ECorA binding sites in a series of gastric, colorectal and pancreatic carcinomas as well as corresponding normal tissues. Additionally, a series of hyperplastic and adenomatous colorectal polyps was analyzed. According to our results, both lectins exhibited a strong reactivity with the great majority of gastrointestinal carcinomas. Regarding gastric carcinomas, a stronger reactivity with intestinal-type compared to the diffuse-type species could be observed. Some poorly differentiated tumors were not or only very faintly stained. In the case of colorectal carcinomas, liver metastases which were investigated comparatively, exhibited the same binding pattern as the primary tumors. Colorectal adenomas were stained in about half of the cases without significant relation to the grade of cellular atypia. Positivity observed in normal epithelia (i.e, gastric superficial epithelia, fundus neck cells and deep pyloric mucous glands, pancreatic acini and ductal structures) is in keeping with histogenetic relations between these normal histological structures and corresponding neoplasms. In areas exhibiting intestinal metaplasia, various portions showed cytoplasmic staining of columnar cells and/or of goblet cell vacuoles. On the other hand, columnar and goblet cells in normal colorectal tissue were only weakly stained in a number of specimens. Therefore, it can be concluded that Gal beta 1-4GlcNAc is overexpressed in neoplastic colorectal tissues. Summarized, ECA and ECorA are suitable tools to analyze the expression of Gal beta 1-4GlcNAc, the common precursor substance of various tumor-associated type 2 chain antigens in neoplastic tissues.