The role of S100A6 in pancreatic cancer development and its clinical implication as a diagnostic marker and therapeutic target

Recent microarray analyses showed that the S100 family contains members that are candidate diagnostic markers or therapeutic targets. In the present study, to evaluate the involvement of S100A6 in pancreatic cancer and its clinical usefulness for diagnosis, we examined S100A6 mRNA expression in pancreatic tissues and pancreatic juice from patients with different pancreatic diseases. To investigate the role of S100A6 in carcinogenesis of pancreatic cancer and the potential of S100A6 as a diagnostic marker for early detection of pancreatic cancer, we did immunohistochemistry and microdissection-based mRNA analysis of pancreatic normal ducts, pancreatic intra-epithelial neoplasias, and invasive ductal carcinomas. We also used in vitro experiments and microarray analysis with RNA interference to evaluate the functional role of S100A6 and its potential as a therapeutic target for pancreatic cancer. S100A6 mRNA levels were significantly higher in carcinoma specimens than in nonneoplastic tissues. In pancreatic juice, there was a significant difference in S100A6 expression between patients with carcinoma and those with nonneoplastic disease. Receiver operating characteristic curves revealed that S100A6 might be a useful marker for diagnosis of pancreatic cancer. Immunohistochemistry and microdissection-based analysis showed differential expression of S100A6 among normal ducts, pancreatic intraepithelial neoplasias, and invasive ductal carcinomas. In vitro data showed that inhibition of S100A6 decreased proliferation and invasiveness of cancer cells, and these findings were supported by microarray data. Our present results suggest that quantitation of S100A6 mRNA is a promising tool for diagnosis of pancreatic cancer, and that S100A6 may be a promising therapeutic target for pancreatic cancer.