The Clinical Value Of The Serum Proteomic Profiling For Diagnosis Of The Esophageal Carcinoma And Gastric Cardia Adenocarcinoma

Objective: Esophageal carcinoma (EC) and gastric cardia adenocarcino- ma(GCA) both are the commom alimentary canal cancer with poor prognosis and low 5-year survival rate. Searching for the effective method for diagnosis, espechially early diagnosis is ciritical for improving prognosis, as well as population screening in the high-risk region. In recent years, fast development of proteomics facilitated numerous attempts of cancer biomarker discovery. Using the proteomic profiling to detection the diseases showed well potentiality and perspective. In this study, matrix-assisted laser desorption/ ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to detect the serum proteomic profiling for detection of esophageal carcinoma and gastric cardia adenocarcinoma: (1) Searching for panels of differentially expressed proteins to construct diagnositic model of EC and GCA; (2) Constructing the diagnositic model for the early detection by comparing the healthy control to stage I-II of EC/GCA, stage I-II of EC/GCA to the stage III-IV. The classification model for EC and GCA were established to evaluate the differential ability of the proteomic profiling.Methods:1 The serum samples of EC, GCA and healthy control were obtained at the Forth Hospital of Hebei Medical University during March of 2009 to May of 2010. The serum bank were established with all of the coded specimens.2 Serum protein was extracted with the weak cation exchange (WCX) protein chip system, and protein fingerprint was examined using MALDI-TOF MS. Every 7 specimens were matched with 1 standard serum.3 The preprocessed and model construction data were handled by the proteinchip data analysis system. The diagnositic models were established using genetic arithmetic (GA) combined support vector machine (SVM). The SVM model with the highest Youden's index was selected as the model. Combinations with the highest accuracy in distinguishing different groups of data were selected as potential biomarkers.4 All samples for constructing the model were randomly split into a training set and a test set. The diagnostic models were evaluated with the test set by leaving one cross validation.5 The further validation was performed with the validation set which were consisted with the new specimens.Results:1 Reproducibility of the MB-WCX separation was estimated with pooled quality control (QC) serum sample. The coefficients of variation (CVs) for peak mass and normalized intensity of the selected peaks were 0.01% and 18%, respectively. These values were consistent with the reproducibility data for the Protein Biology System reported by the manufacturer.2 Pattern 1 was constructed to evaluate the differentially expressed proteins between EC pateints and healthy controls formed by 11 peaks. The protein peaks positioned at 4 645, 4 092 and 4 210 Da were found up-regulated and the other 8 peaks down-regulated in EC group. The sensitivity and specificity from the test set by leaving one cross validation were 88.13% and 80.35% respectively. The classification model distinguished the validation set with a sensitivity of 85.43%, specificity of 83.75%.3 Pattern 2 was formed by the combination of spectral amplitudes at 7 precise M/Z values. In addition, the expression of 2 863, 3 241 Da proteins progressively increased with the clinical stage, and the level of 3 883, 3 257, 3 952, 4 194 Da proteins gradually decreased in advanced stages. When evaluated using the validation set, the sensitivity and specificity of Pattern 2 were 93.37% and 90.58%, respectively.4 Pattern 3 and 4 were compared the healthy control to stage I-II of EC, stage I-II of EC to the stage III-IV. Pattern 3 was formed by 8 protein peaks, the sensitivity was 96.21%, the specificity was 96.83%. Pattern 4 was consisted with 8 differential protein peaks, the sensitivity and specificity were 86.45% and 85.36%, respectively.5 Pattern 3 and 4 were compared the healthy control to stage I-II of GCA, stage I-II of GCA to the stage III-IV. Nine differential peaks were screen out to construct the pattern 5. The sensitivity and specificity were 90.36% and 91.59%. Pattern 6 was formed by 5 protein peaks, all of the protein peaks were down-regulated in the advanced stage of GCA . The sensitivity were 70.23%, the specificity was 88.56%.6 For the discriminating EC patients from GCA patients, pattern 7 was formed by the combination of spectral amplitudes at five precise M/Z values (1 520, 1 546, 1 866, 3 192 and 1 628 Da). When evaluated using the validation set, the sensitivity and specificity of Pattern 7 were 80.37% and 69.33%, respectively.Conclusions:1 The reproducibility of the study was ensured following the standardized protocol (ClinProt SOP) in specimens collection and processed, which ensured the the detection of the MALDI-TOF MS.2 MALDI-TOF MS based serum proteomic profiling for detection of esophageal carcinoma and gastric cardia adenocarcinoma performed high sensitivity and specificity, which were helpful for clinical diagnosis.3 The expression of the peaks of pattern 2 progressively increased or decreased with the clinical stage, which provided new clews in searching for the pathogenesy or targeted therapy of GCA.4 The patterns for diagnosis early stage of EC and GCA with high sensitivities and specificitise which were promising in early diagnosis and therapy of EC and GCA.5 The pattern for differentiation EC from GCA was helpful to the discriminate diagnosis.