A64
Early stage pancreatic cancer protein biomarkers
Seonaid Murray, Sarah Tonack, Mark Aspinall-O'Dea, Roz Jenkins, Victoria Elliot, Cathy Lane, Bill Greenhalf, John Neoptolemos, Eithne Costello
1University of Liverpool, UK, 2Applied Biosystems, Warrington, UK
Background
Cancer cells release proteins into the blood. If we can detect and identify these proteins, they may be used as biomarkers for the disease. The objective of this study is to find protein biomarkers for early stage pancreatic cancer.
Method
Serum was taken from 5 patients with early stage pancreatic cancer (T1/3N0 tumours), 5 with late stage pancreatic cancer (T3N1 tumours), 5 with chronic pancreatitis, and 5 healthy individuals. The serum from each group of patients was pooled and depleted of 20 highly abundant serum proteins. The remaining proteins were digested with trypsin. The resulting peptides were labelled with Isobaric Tags for Relative and Absolute Quantification (iTRAQ) reagents. Each pool was labelled with a different iTRAQ reagent. The four pools were combined and strong cationic exchange (SCX) chromatography was performed followed by reversed phase liquid chromatography electrospray ionisation tandem mass spectrometry (LC-ESI-MS/MS). The proteins that were identified were mapped onto protein pathways and networks.
Results
We identified 254 proteins and quantified 234 proteins with greater than 95% confidence. Of these proteins, 19 were up-regulated (≥ 2-fold) in the early stage cancer group compared to the control groups (chronic pancreatitis and healthy individuals), and 21 were down-regulated (≥ 2-fold) in early stage cancer compared to controls.
To estimate the chance that the individual protein (or peptide) is actually present in the sample we calculated the false discovery rate, and identified 217 proteins (5773 peptides) with a false discovery rate of 1%.
Conclusion
Proteins were identified and quantified in serum samples from different patient groups. These potential protein biomarkers for early stage pancreatic cancer are now being validated.
