EXPRESSION OF GAL-BETA-1-4GLCNAC SEQUENCES BY HUMAN GASTROINTESTINAL NEOPLASMS AND THEIR PRECURSORS AS DETECTED BY ERYTHRINA-CRISTAGALLI AND ERYTHRINA-CORALLODENDRON LECTINS

Lectins from Erythrina cristagalli (EGA) and Erythrina corallodendron (ECorA) are well-known to detect type 2 chain oligosaccharides (Gal be ta 1-4GlcNAc). These carbohydrate moieties are the biosynthetic precur sors of various ABH and Lewis blood group antigens and are therefore a lso related to tumor-associated carbohydrate antigens. For this reason , we investigated the expression of ECA and ECorA binding sites in a s eries of gastric, colorectal and pancreatic carcinomas as well as corr esponding normal tissues. Additionally, a series of hyperplastic and a denomatous colorectal polyps was analyzed. According to our results, b oth lectins exhibited a strong reactivity with the great majority of g astrointestinal carcinomas. Regarding gastric carcinomas, a stronger r eactivity with intestinal-type compared to the diffuse-type species co uld be observed. Some poorly differentiated tumors were not or only ve ry faintly stained. In the case of colorectal carcinomas, liver metast ases which were investigated comparatively, exhibited the same binding pattern as the primary tumors. Colorectal adenomas were stained in ab out half of the cases without significant relation to the grade of cel lular atypia. Positivity observed in normal epithelia (i.e, gastric su perficial epithelia, fundus neck cells and deep pyloric mucous glands, pancreatic acini and ductal structures) is in keeping with histogenet ic relations between these normal histological structures and correspo nding neoplasms. In areas exhibiting intestinal metaplasia, various po rtions 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. T herefore, it can be concluded that Gal beta 1-4GlcNAc is overexpressed in neoplastic colorectal tissues. Summarized, ECA and ECorA are suita ble 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.