[Study on proliferating potential by Ag-NORs staining in human pancreatic carcinoma]

NORs (Nucleolar Organizer Regions) are loops of DNA encoding ribosomal RNA, which reflect cellular activity. The Ag-NORs staining was applied to paraffin sections of 10 normal pancreas, 10 chronic pancreatitis and 23 pancreatic cancer, with 17 gastric and 18 colonic cancers. We calculated the mean Ag-NORs number and Ag-NORs index, and defined T/N ratio. The mean Ag-NORs number was compared with the data obtained by Flow cytometry (FCM) in pancreatic carcinoma. A significant difference in Ag-NORs index was found between benign (normal: 1.86 +/- 0.38, pancreatitis: 2.14 +/- 0.53) and malignant tissues (4.02 +/- 1.19) of the pancreas (p < 0.01). Compared with the data by FCM, there was a significant correlation between the mean Ag-NORs number and the percentage of S-phase cells in pancreatic carcinoma (r = 0.59, p < 0.01). Ag-NORs index in pancreatic carcinoma showed significantly lower value than that in cancer of stomach (6.35 +/- 1.32) and colon (7.66 +/- 1.35), but there was no difference in T/N ratio among them. In conclusion, the Ag-NORs staining is useful for analyzing proliferating activity in pancreatic carcinoma. The proliferating potential in pancreatic carcinoma is lower than that in gastric and colonic ones. This may be due to the low proliferating potential of the background mucosa from which pancreatic carcinoma will arise.