Differentiating pancreatic lesions by microarray and QPCR analysis of pancreatic juice RNAs

The gene expression profile of pancreatic cancer is significantly different from that of normal pancreas. Differences in gene expression are detectable using microarrays, but microarrays have traditionally been applied to pancreatic cancer tissue obtained from surgical resection. We hypothesized that gene expression alterations indicative of pancreatic cancer can be detected by profiling the RNA of pancreatic juice.

We performed oligonucleotide microarray analysis on RNA isolated from pancreatic juice obtained endoscopically after secretin stimulation from six patients with pancreatic cancer and ten patients with nonneoplastic diseases of the pancreas or upper gastrointestinal tract. Extracted RNA was subjected to two rounds of linear RNA amplification, and then hybridized with U133A or X3P gene chips (Affymetrix).

Using the U133A or X3P chips, 37 and 133 gene fragments respectively, were identified as being at least 3-fold more abundant in the pancreatic juice of patients with pancreatic cancer compared to the noncancer controls (p<0.05, Mann-Whitney test). For example, pancreatic juice from patients with pancreatic cancer contained increased levels of IL8, IFITM1, fibrinogen, osteopontin, CXCR4, DAF and NNMT RNA, genes that have been previously reported as overexpressed in primary pancreatic cancers or pancreatic cancer cell lines relative to control tissues.

These results demonstrate that RNA analysis of pancreatic juice can reveal some of the same RNA alterations found in invasive pancreatic cancers. RNA analysis of pancreatic juice deserves further investigation to determine its utility as a tool for the evaluation of pancreatic lesions.