The roles of inducible nitric oxide synthase expression in pancreatic cancer / 대한내과학회지

ABSTRACT

BACKGROUND: The finding of frequent inducible nitric oxide synthase (iNOS) expression in human cancer indicates that nitric oxide has a pathological role in tumor progression. Increased expression of iNOS in human pancreatic cancer cells was also recently reported, but the clinicopathological and biological significance of the iNOS expression remains unclear. The aim of our study was to look for possible roles and clinical significance of iNOS expression in pancreatic cancer. METHODS: 72 pancreatic adenocarcinoma tissue specimens were obtained from surgical resection. We investigated the immunohistochemical expression of iNOS in respect to variable clinicopathological characteristics, proliferation activity (assayed by Ki-67 expression), apoptosis (by TUNEL stain), and microvessel density (by CD34 expression; angiogenesis). RESULTS: Immunohistochemical positivity for iNOS in pancreatic epithelial cells was observed in 48/72 (66.7%). Apoptotic index (AI) of positive iNOS expressions were significantly higher than for negative expression (p <0.001) and increasing intensity of COX-2 expression showed a trend with increasing AI (p<0.001). No significant association was found between iNOS expression and proliferation index or microvessel density in pancreatic cancer. The expression of iNOS protein did not correlated with age, bilirubin, CA 19-9, location, size, AJCC stage, differentiation, distant metastasis or patient survival. CONCLUSION: The expression of iNOS enzyme in pancreatic cancer contributes to apoptosis of tumor cells. However, we could not find any correlation between iNOS expression and cell proliferation, angiognesis or clinical characteristics. Further in vivo investigations are necessary to determine the putative role of the iNOS expression for tumor progression in human pancreatic cancer.