Immunohistochemical staining of Ha-ras oncogene product in normal, benign, and malignant human pancreatic tissues.

We examined immunohistochemical staining with Ha-ras oncogene product in normal, benign, and malignant human pancreatic tissues. In cases of pancreatic cancer, its relation to histologic type was evaluated. Serous cystadenoma and atypical acinar cell nodules did not react with the Ha-ras oncogene product, and ductal cells and acinar cells in normal pancreas showed lower immunoreactivity than other benign or malignant lesions. However, the positive rate of islet cells in normal pancreas was almost the same in cases of pancreatic cancer. Strongest positivity was observed in cases of chronic pancreatitis, and islet cell tumors also showed high positive staining rates. In pancreatic cancer, the positive rate of well-differentiated adenocarcinomas was rather higher than that of poorly differentiated adenocarcinomas. Our study indicates that the Ha-ras oncogene p21 product does not correlate with neoplastic transformation in human pancreas, is not a useful marker for differentiating benign and malignant lesions, and cannot be used to determine the origin of differentiation in the pancreas.