Differential Proteomics Analysis of Tumor Tissues and Their Adjacent Normal Tissues from Patients with Colorectal Cancer by Gel Electrophoresis-Capillary Liquid Chromatography-Mass Spectrometry-based Approach

The whole protein extracts from tissue specimens (tumor and noncancerous) from patients with colorectal cancer were divided into several fractions with different molecular weight by gel electrophoresis, which were then subject to in-gel digestion and proteomics analysis by capillary liquid chromatography-mass spectrometry. A total of 29 differentially expressed proteins were identified, among which 19 were up-regulated proteins in tumor tissues, such as Fibrinogen beta chain, Vimentin, Fibrinogen gamma chain, Histone H2A type 1-B/E, Isoform 1 of Periostin, Fibrinogen alpha chain, Histone H3. 1, Alpha-enolase, Protein disulfideisomerase A3, and so on. Ten proteins were found to be down-regulated, including Sarcomeric tropomyosin kappa, Transgelin, Heat shock protein beta-1, Talin-1, Isoform 2 of Vinculin, Isoform 1 of Filamin-C, and so on. The differential expressions of Talin-1 and Alpha-enolase were selected to be verified by Western blot analysis. Bioinformatics analysis results indicated that most of the up-regulated proteins in colorectal cancer tissues had the feature of protein exocytosis, suggesting that these proteins were likely to penetrate into the circulatory system in the body, which could be detected in blood or ascites. On the other hand, most of the down-regulated proteins belonged to the cytoskeleton and extracellular matrix fibers, which were closely related to the invasion and metastasis of tumor cells into their surrounding tissues. This study provided basic data for the early diagnosis of colorectal cancer, colorectal cancer screening and other aspects, which had important significance to further study the pathogenesis of colorectal cancer.