A Mr 58,000 glycoprotein specifically expressed in developing hamster pancreas and reexpressed in hamster and human pancreatic carcinomas.

A glycoprotein with a molecular weight of 58,000 specifically expressed in exocrine hamster fetal pancreas was characterized using a monoclonal antibody (Mab B4). By immunoperoxidase, Mab B4 stained pancreatic tissue from the 10th day of gestation (6 days before delivery) until the 10th day after birth. The maximal expression of the Mab B4-specific protein called fetal pancreatic (FP) protein was reached between delivery and the 5th day of postnatal life. Endocrine pancreas was negative at any developmental stage. All adult pancreata examined were negative. Moreover, Mab B4 was tested against a wide variety of fetal and adult tissues; only immature pancreata were stained. Chemically induced pancreatic carcinomas were strongly stained by this Mab. On the contrary, other tumors (liver and kidney) appearing simultaneously with pancreatic carcinomas were negative. Using a nitrocellulose immunofixation assay, FP protein was found in all sera from hamsters bearing pancreatic tumors (23 cases tested). This protein was not detected in normal sera. Mab B4 cross-reacted with a protein in human fetal pancreas extracts, that behaves similarly to the hamster FP protein: it is present exclusively in exocrine fetal pancreas and is reexpressed in pancreatic adenocarcinomas. The high tissue specificity of this protein, its oncofetal character, and release into the blood circulation make the FP protein a potential tumor marker of pancreatic cancer.