THE IDENTIFICATION OF A NOVEL NCA-RELATED PANCREATIC TUMOR ASSOCIATED ANTIGEN, DD9-ANTIGEN - A COMPARISON WITH THE EXPRESSION OF OTHER TUMOR-ANTIGENS BY THE PANCREATIC TUMOR-CELL LINE GER

Pancreatic tumour-associated monoclonal antibody DD9E7, raised against the GER pancreatic adenocarcinoma cell line, recognises a protein epitope on a novel family of membrane-bound cell surface glycoproteins (M(r) 80-115,000). Western blot analysis of SDS/PAGE gels of tumour biopsies and of normal adult pancreas has shown that these glycoproteins are highly expressed in most pancreatic tumours but cannot be detected in normal adult pancreas. Using monoclonal antibodies directed against other antigens that have been associated with pancreatic adenocarcinoma (Du-Pan-2, Ca 19-9, CEA, NCA-95/55, EMA, and FAP), we have been able to show that although some of the antigens are also expressed by the GER pancreatic tumour cell line, the glycoproteins identified by monoclonal antibody DD9E7 are distinct from those other antigens in both molecular weight and antibody binding characteristics. Neuraminidase, periodic acid, and tunicamycin treatment of cultured cells has shown that monoclonal antibody DD9E7 recognises an epitope on the protein core of the antigen. This epitope is also present in NCA-1, but not in CEA, which suggests that there may be an association between DD9-antigen and other members of the NCA/CEA supergene family.