Co-expression of human cancer-associated epitopes on mucin molecules

This work describes the immunochemical comparison of mucin-like high-molecular-weight glycoproteins associated with human malignancies that are defined by murine MAbs, DU-PAN-2, 19-9, OC-125, B 72.3, and Mov 2. These MAbs were originally elicited to human adenocarcinomas from different organ sites such as pancreas, colon, ovary, and breast, respectively. Although each antibody recognizes an antigen on tumors of the same type as the tumor used for immunization, there is often considerable cross-reactivity with adenocarcinomas from other organ sites. Additionally, these antigens have common properties of large molecular size, high carbohydrate content, and molecular size heterogeneity. Three antigens, CA 19-9, Mov 2, and DU-PAN-2, demonstrated size heterogeneity on agarose gel immunoblotting with their respective antibodies and gave different migration patterns from sera, bile, and pancreatic juice of patients with pancreatic adenocarcinoma. Data from inhibitory double determinant analyses indicated that the DU-PAN-2, CA 19-9, CA 125, TAG-72, and Mov 2 epitopes are distinct and non-cross-reactive. However, immunoblotting and affinity chromatography indicated that both 19-9 and DU-PAN-2 epitopes may be co-expressed on the same mucin molecule in varying proportions.