title: Molecular characterization of a mucin-type antigen associated with human pancreatic cancer. The DU-PAN-2 antigen.
abstract: This work describes the molecular characterization of a human pancreatic cancer-associated antigen defined by a murine monoclonal antibody (DU-PAN-2). DU-PAN-2 antigen was isolated from a pancreatic adenocarcinoma cell line (HPAF) or patient's ascitic fluid, and the antigenic activity was monitored by competitive inhibition radioimmunoassay. Affinity chromatography and CsCl/guanidine HCl density gradient centrifugation were employed to remove other populations of mucin-type glycoproteins and noncovalently associated proteins, respectively. Three electrophoretically distinct components were detected by 1% agarose gel electrophoresis and were resolved by chromatography on Sepharose CL-4B. The major fraction (FII) was subjected to carbohydrate and amino acid analyses. The sum of threonine, serine, proline, glycine, and alanine comprised more than 50% of the amino acid residues. The saccharide units, O-glycosidically linked to the peptide via GalNAc, contained fucose, galactose, GlcNAc, GalNAc, and sialic acid. The total carbohydrate content of FI and FII was 80.8% and 77.4% by weight, respectively. The molecular weight of FII antigen showed two species of molecules of 1.45 X 10(6) and 4.59 X 10(6) by analytical sedimentation equilibrium. DU-PAN-2 antigen was susceptible to neuraminidase, pepsin, Pronase, and papain digestion. These results suggest that both protein components and sialic acid residues may play important roles in the binding of DU-PAN-2 antibody.
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000912:Antibodies, Neoplasm / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology*; D002460:Cell Line; D002846:Chromatography, Affinity; D004587:Electrophoresis, Agar Gel; D000939:Epitopes / Q000276:immunology; D006801:Humans; D051379:Mice; D009077:Mucins / Q000276:immunology*; D009363:Neoplasm Proteins / Q000276:immunology; D009439:Neuraminidase; D010084:Oxidation-Reduction; D010190:Pancreatic Neoplasms / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; C042317:DU-PAN-2 antigen, human; D000939:Epitopes; D009077:Mucins; D009363:Neoplasm Proteins; D009439:Neuraminidase