Differentially Expressed Proteins Analysis Based On Mass Spectrometry In Colorectal Cancer

The occurrence and development of tumor is a process involving multiple pathophysiology in the body.And protein plays an important role in the regulation of these processes,which can be used as an objective indicator of tissue biological status.Cells adapt to changes in the internal and external environment by regulating the expression level and activity of their proteins.Therefore,proteins reflect a condition of cells in activity,both qualitatively and quantitatively.Mass spectrometry(MS)is a high-throughput method for systematic and large-scale analysis of protein abundance.As a powerful tool for structure analysis of proteomics,it can provide more information for structural qualitative and quantitative study.Colorectal cancer(CRC)is an important field of proteomics research.In recent years,proteomics and related technologies have made some progress in their application of colorectal cancer.Objective: 1.To investigate the difference of protein expression in serum between colorectal cancer patients and normal controls by mass spectrometry;2.To conduct bioinformatics qualitative classification and functional analysis of the differentially expressed proteins.We expected to provide more information about the development of colorectal cancer from the perspective of protein.Methods: A case-control study was conducted in which 50 patients with colorectal cancer and 50 healthy controls matched for age and sex were included.Basic information of the participants and clinical and pathological data of the case group were collected.The expression levels of different peptides/proteins in serum were detected by matrix-assisted laser desorption/ ionization time of flight mass spectrometry(MALDI-TOF-MS).Thermo Proteome Discoverer 2.1 software was used for protein retrieval and identification.Biological information and functional classification of differentially expressed proteins in the CRC group compared to healthy controls were further analyzed by searching the Gene Ontology(GO),DAVID and Kyoto Encyclopedia of Genes and Genomes(KEGG)databases.STRING 9.0 software was used to identify associations and interactions between proteins.Results: 1.In the CRC group and the normal control group,a total of 64 protein peaks were detected by MALDI-TOF-MS.14 proteins were differentially expressed between groups(P<0.05),among which 9 proteins were up-regulated and 5 proteins were down-regulated in CRC patients.2.Comparing the colorectal cancer group with the normal control group,further qualitative classification and functional analysis of differentially expressed substances revealed that these proteins were predominantly extracellular substances(64.4%)and were mainly involved in molecular functions associated with binding.The differentially expressed proteins were related in the activation of the complement system and the coagulation system,inflammation and immune response,signal transduction and other processes.Among all the identified proteins,kininogen-1(KNG1),clinsterin(CLU),complement C3(C3)and fibrinogen alpha chain(FGA)were related to the occurrence and development of tumors.Conclusions: 1.There is a difference in serum protein profiles between colorectal cancer and normal controls.Proteomics can partially reflect the pathophysiological processes occurring in tumor patients.2.Various proteins interact with each other and participate in the regulation of physiological processes in tumorigenesis and development.KNG1,CLU,C3 and FGA are tumor-related indicators for colorectal cancer.