Human pancreatic ribonuclease 1 - Expression and distribution in pancreatic adenocarcinoma

BACKGROUND. Human pancreatic ribonuclease (RNase 1) is a pancreatic enzyme that is present at high levels in the serum of most patients with pancreati c adenocarcinoma. For this reason, the authors studied its patterns of expr ession at the single-cell level in pancreatic adenocarcinoma tissues by imm unohistochemical analysis and in situ hybridization (ISH). METHODS. Immunohistochemical analysis with polyclonal antibodies against RN ase 1 and by ISH with digoxigenin-labeled RNase 1 probe were used to detect RNase 1 in the neoplastic cells of ductal type pancreatic adenocarcinomas. RESULTS. Fifteen of 18 carcinoma samples were positive for RNase 1, demons trating that the expression of ribonuclease that the authors observed previ ously in human pancreatic adenocarcinoma cell lines was not an artifact of cell culture. The authors also found RNase 1 in some of the metaplastic duc ts and atrophic islets in 4 of 6 chronic pancreatitis samples, and they obs erved RNase 1 immunostaining in hyperplastic ducts adjacent to one of the w ell-differentiated adenocarcinomas. CONCLUSIONS. The expression levels of RNase 1 by tumor cells from pancreati c adenocarcinomas are consistent with the high RNase 1 levels found in the serum of most patients with pancreatic adenocarcinoma. This expression of R Nase 1, which is an acinar protein, demonstrates that the patterns of gene expression in pancreatic adenocarcinoma are distinct from those of normal p ancreatic duct cells. Conversely, RNase 1 expression levels in altered duct al cells from some chronic pancreatitis tissues and hyperplastic ducts from carcinoma tissues suggest that abnormal expression levels may be an early event in pancreatic tumorigenesis. (C) 2000 American Cancer Society.