Separationand Identification Of Differentially Expressed Proteins Of Gastric Adenocarcinomas Tissue

In recent years, we have in-depth understanding of tumor related genesdue to thehigh-throughput genomics technology.Although, it is not enough toenableustoanalyzes the mechanism of tumorigenesis at the molecular level deeply,since the genomics technology cannot monitor the transcription/post-translationalmodifications and protein-protein interaction at protein level.Thus, it is necessarytoresearch on the tumor associated proteins meticulously using proteomicstechnology. Two-dimensional gel electrophoresis(2-DE),which invented by O’Farrellin1975,is a core technology of the proteomics technology. And its basic principle isto separate proteins using the isoelectric and molecular weight of them.Thistechnology can help us to separateand identifythe differentially expressed proteinsbetweencancer tissues and common tissues. These proteins can be used as specificbiomarkers of cancer and potential diagnostic tools.As a common malignant tumor, the mortality rate of gastric cancer is about750000per year around the world which is second highest among all cancers. Themajor cause of the high mortality rate is the low early diagnostic rate, less than halfof patients can be diagnosed in the early stage of gastric cancer.According to thesurvey of AJCC, the5-year survival rate of stage Ⅳ gastric cancer patients is only7%to10.1%. Meanwhile the rate of early gastric cancer (stage ⅠA) could reach78%to93.3%. Therefore, it is criticalto enhance the early diagnostic rate for improving theprognosis of gastric cancer patients. Using proteomics technology, we can study theclinical samples and find related molecular markers of tumor. Such markers cannotonly be the basis of developing new methods for early diagnosis, but also be theclues of understanding the occurrence and development of tumors.Gastric adenocarcinoma, which account for roughly90%, is the most commonpathological type ofgastric malignant tumor.We hope that the separation anddetection rate of alkaline region and low abundance proteins can be enhancedthrough the optimizing of two-dimensional electrophoresis technology. Therefore, we canimprove the proteins profile resolution of gastric cancer and normal gastric tissues.In the first part of this study, we use four gradient pH range IPG strips which pHrange overlapped to run the2-DE. Then,we have got the total protein maps ofgastric cancer and normal gastric tissue respectively. By analyzingthe2-DE profileof gastric adenocarcinoma tissues and paired normal stomach tissues, we have foundout115differentially expressed proteins. In the second part of this study, we haveidentified70differentially expressed proteins base on the MALDI-TOF-MS massspectrometry identification and database retrieval. Altogether,27types of proteinsare overexpressed and down-regulated expression in the gastric adenocarcinomatissues respectively.In the third part of the study, we have verified preliminarily thatthe expression of AKR7A3is reduced in the gastric adenocarcinoma tissues usingwestern blotting. However, the relationship between the expression level ofAKR7A3and gastric adenocarcinoma needs to be further confirmed through massiveimmunohistochemical experiment(tissue microarray).