Pancreatic trypsinogen expression in 149 surgically resected extrapancreatic gastrointestinal neoplasms was evaluated immunohistochemically. Immunohistochemistry was performed using a monoclonal antibody against human pancreatic trypsinogen. Pancreatic trypsinogen expression was detected in 28 of 55 gastric carcinomas (50.9%), 22 of 44 colorectal cancers (50%), 12 of 20 gallbladder cancers (60%), nine of 10 extrahepatic bile duct cancers (90%), and none of 20 hepatocellular carcinomas. The intensity of immunoreactivity in the tumor area varied from specimen to specimen, and from area to area within the same specimen. In most cases, however, immunoreactivity was more pronounced at the infiltrative margin of the tumor. Additionally, the highly differentiated carcinoma cells tended to display a focal, fine granular immunoreactive pattern, usually present in the supranuclear cytoplasm, while the poorly differentiated carcinoma cells displayed a fine granular pattern, usually present over the entire cytoplasm. These findings suggest that some extrapancreatic gastrointestinal neoplasms express pancreatic trypsinogen immunoreactive peptides, raising the possibility that secreted pancreatic trypsinogen plays a role in carcinoma invasion and metastasis, as has been shown for other classes of proteases.

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