Glycolipids carrying Ley are preferentially expressed on small-cell lung cancer cells as detected by the monoclonal antibody MLuC1

The monoclonal antibody MLuC1, which reacts strongly with a high percentage of small-cell lung cancers (SCLC), as well as with various human carcinomas, has been used to immunochemically characterize the recognized epitope (CaMLuC1). To this aim 3 different approaches were adopted: (1) immunoblotting/immunostaining of extracts from various tumor-cell lines; (2) inhibition of binding by purified oligosaccharides; (3) direct binding to oligosaccharide-protein conjugates. All of these experiments indicate that CaMLuC1 is present on the Le(y) blood-group structure heterogeneously expressed on various glycoproteins and glycolipids. The expression of the glycoconjugates carrying Le(y) was then analyzed on breast and lung cancers and on their normal counterparts. Our overall results suggest that SCLC produce Le(y)-active glycolipids in higher amounts compared to other tumors of the same or of a different oncotype, as well as normal lung cells, thus indicating an SCLC-specific modification of the glycosylation pathways.