Conclusion: Pancreatitis-associated protein (PAP) mRNA is expressed in some cases of gastric and colorectal cancers resulting from an ectopic expression in dedifferentiated cancer cells.
Background: The PAP gene is identical to the hepatoma-intestine-pancreas (HIP) gene, which is expressed in hepatoma. Expression in cancer might be another characteristic of PAP.
Methods: Fresh surgical specimens of 100 gastrointestinal cancers, 14 benign digestive diseases, and six normal organs were studied with nonisotopic in situ hybridization (ISH) using biotin-labeled cDNA probe.
Results: PAP mRNA was detected in 10% (6/60) of gastric cancers, 21.4% (6/28) of colorectal cancers, 20.0% (1/5) of pancreatic cancers and 0% of biliary tract (three), esophageal (one), and hepatocellular cancers (three). Reverse transcription-polymerase chain reaction (RT-PCR) detected PAP mRNA in these ISH-positive cases. PAP mRNA was not detected in noncancerous portions, benign disease tissues, or normal organs except for the small intestine. There was no relationship between PAP mRNA expression and any clinicopathological factors.