Increased Expression of Sialyl-Dimeric Lex Antigen in Liver Metastases of Human Colorectal Carcinoma

We collected a total of 78 tissue specimens, including primary colorectal carcinoma, normal colonic mucosa, and liver metastases of colon carcinoma, to examine whether the extracts of these tissues inhibited the binding of a monoclonal antibody FH6, specific for sialyl-dimeric Lex antigen. The results of inhibition assays demonstrated that: ( a ) contents of FH6-reactive molecules were greater in carcinoma tissues than in normal colonic mucosa; ( b ) metastatic foci in livers contained more FH6-reactive molecules than primary tumors; ( c ) primary tumors from Dukes' stage B1 patients contained less FH6-reactive molecules than primary tumors from Dukes' stage D patients. The inhibitory activity of these tumor tissue extracts against the binding of a monoclonal antibody FH6 to cultured colon carcinoma cells was eliminated by prior treatment of the extracts with sialidase, confirming that the FH6-reactive materials were sialyl-dimeric Lex antigen. Electrophoretic separation of tumor tissue extracts on 3% polyacrylamide gels followed by direct staining with monoclonal antibody FH6 revealed that very high molecular weight glycoproteins, presumably mucins, contained sialyl-dimeric Lex antigen.