Global microRNA expression patterns of many embryologic, physiologic, and oncogenic processes have been described.
However, the description of the role of microRNAs in ductal adenocarcinoma of the pancreas is lacking.
Dr Mark Bloomston and colleagues defined the expression pattern of microRNAs in pancreatic cancer.
The research team compared it with those of normal pancreas and chronic pancreatitis.
|21 MicroRNAs with increased expression differentiated 90% of samples|
|Journal of the American Medical Association|
The team obtained specimens at a National Cancer Institute-designated comprehensive cancer center.
The team evaluated 65 patients with ductal adenocarcinoma of the pancreas, and 42 patients with chronic pancreatitis between 2000 and 2005.
All patients underwent curative pancreatectomy.
Those with pancreatic cancer were chemotherapy-naive.
RNA harvested from resected pancreatic cancers was hybridized to microRNA microarrays.
The researchers matched the RNA with benign adjacent pancreatic tissue as well as from chronic pancreatitis specimens.
The main outcome was identification of differentially expressed microRNAs that could differentiate pancreatic cancer from normal pancreas, chronic pancreatitis, or both.
The research team also observed patterns of microRNA expression predictive of long-term survival.
Significance of Analysis of Microarrays and Prediction of Analysis of Microarrays were undertaken to identify microRNAs predictive of tissue type and prognosis.
Kaplan-Meier survival curves were constructed using mean microRNA expression as threshold and compared by log-rank analysis.
The researchers found 21 microRNAs with increased expression that correctly differentiated pancreatic cancer from benign pancreatic tissue in 90% of samples.
The team identified 4 microRNAs with decreased expression that differentiated pancreatic cancer from benign pancreatic tissue in 90% of samples.
There were 15 over expressed, and 8 underexpressed microRNAs differentiated pancreatic cancer from chronic pancreatitis with 93% accuracy.
A subgroup of 6 microRNAs was able to distinguish long-term survivors with node-positive disease from those dying within 24 months.
In addition, the team found that high expression of miR-196a-2 was found to predict poor survival.
Dr Bloomston's team concluded, "Pancreatic cancer may have a distinct microRNA expression pattern that may differentiate it from normal pancreas and chronic pancreatitis."
"MicroRNA expression patterns may be able to distinguish between long- and short-term survivors, but these findings need to be validated in other study populations."