Comprehensive Study On Human Duodenal Juice Proteomics

Background:Pancreatic cancer is one of the most formidable malignant tumors worldwide.According to the cancer statistics report in 2007,pancreatic cancer is the fourth most common cause of cancer death in the United States.Early detection is the most feasible strategies to improve outcome.Unfortunately,the biomarkers currently available for pancreatic cancer lack adequate sensitivity and specificity.In recent years, there has been a substantial interest in applying proteomics technologies to identify protein biomarkers for early detection of cancer.There is no report on duodenal juice proteomics analysis up to date.Objectives and Methods:In the present study,we collected human duodenal juice as our study samples.Duodenal juice was first fractionated by 1-DE or 2-DE and subsequently analyzed by LC-MS/MS or MALDI-TOF/TOF.Our objectives are as following:1) to explore an effective sample preparation method;2) to establish the duodenal juice proteomics study method;3) to establish the 1-DE gel protein database of duodenal juice;4) to evaluate the feasibility of identifying biomarker from duodenal juice,substituting for pancreatic juice.Results:1) Ultra-centrifugation has great performance in salt removal and protein enrichment.When mixed with pure water,duodenal juice remained stable during the ultra-centrifugation process.2) Degradation will occur when duodenal juice is mixed with rehydration stock solution during first-dimension isoelectric focusing process. PIC is able to improve this condition.3) 1-DE images of 44 cases can be divided into three categories.4) Duodenal juice was fractionated by 1-DE and analyzed by MALDI-TOF/TOF.A total of 33 unique proteins were identified including 3 types of pepsin.5) 1-DE image and protein composition of both duodenal juice and pancreatic juice are in good concordance.Conclusions:1) Ultra-centrifugation is an effective sample preparation method in removing salt and enriching protein.When mixed with pure water,duodenal juice remains stable during this process.2) Degradation occurs during first-dimension isoelectric focusing process.3) Duodenal juice 1-DE images are divided into three categories.Contamination of gastric juice may be the cause of Typeâ…¡image.4) Establish the 1-DE gel protein database of duodenal juice.5) Duodenal juice can assist the pancreatic juice proteomics analysis study.