Antigen heterogeneity in advanced colorectal and breast cancer.

The association of several monoclonal antibody defined tumour-associated antigens with colorectal and breast carcinoma tissues was investigated by immunocytochemistry. The antigens included CEA and the related antigen, NCA (NCA-1), modified blood group substances (Le(y) hapten), a tumour glycolipid antigen and the MUC1 mucin. The molecular expression of these antigens in tumour cell membranes was analysed by identification of antigens in detergent extracts by SDS-PAGE analysis and Western blotting. The capacity of viable tumour tissue to release these antigens as soluble components into short term tissue culture supernatants was further examined. The findings provide a basis for the defining those membrane-associated antigens which would be appropriate targets for monoclonal antibody based targeted therapies in colorectal and breast cancer.