Screening And Analysis Of Prognostic Genes In Colon Mucinous Adenocarcinoma Based On Bioinformatics

Background:Mucinous adenocarcinoma(Mucinous adenocarcinoma,MAC)of colon is an unusual pathological subtype of colon cancer.Compared with common adenocarcinoma(Adenocarcinoma,AC)of colon,MAC is characterized by poor differentiation,higher lymph node and peritoneal metastasis,and poor response to chemotherapy.Due to the difficulty in the construction of colonic MAC cell lines and organoids,the molecular biological mechanisms and related signaling pathways have not been widely studied.Objective: Bioinformatics methods were used to explore the unique signaling pathways of colonic MAC,screen for key genes that can independently predict the prognosis of colonic MAC patients,and verify their expression through histological analysis,providing potential targets for the diagnosis and treatment of colonic MAC.Methods: 1.Download the transcriptome sequencing data and complete clinical data of colon cancer patients from TCGA database.After correction,gene transcription profiles of 501 colon cancer samples were obtained,of which 64 were MAC tissues,398 were AC tissues,and 39 were normal colon tissues.Differential genes(Differentially expressed genes,DEGs)between colonic MAC and AC,and between colonic MAC and normal colonic tissues were screened by DESeq2 package of R-studio software with filter condition of DFR < 0.01 and | log2 Fold Change | >1.5.Through the "Clusterprofiler" package,these differentially expressed genes were respectively analyzed by Gene ontology(Gene ontology,GO)and enrichment analysis of Kyoto encyclopedia of genes and genomes(Kyoto encyclopedia of genes and genomes,KEGG).2.The protein-protein interaction(protein-protein Interaction,PPI)network was constructed according to the differential genes between colonic MAC and AC,colonic MAC and normal colonic tissue,and the common core genes of the two groups of differential genes were obtained by using Cytoscape software.The genes that have influence on the prognosis of colonic MAC among the common core genes were screened by K-M method.Through Cox regression analysis to verify whether this gene is an independent predictor of prognosis in colon MAC patients.The expression of core genes affecting the prognosis of patients with colonic MAC was verified by immunohistochemical staining.Download the microsatellite status of colon MAC patients and test whether there is a statistical difference in the expression level of this gene among patients with different microsatellite status.Results: 1.A total of 491 differential genes were obtained between colonic MAC and colonic AC,including 317 up-regulated genes and 174 down-regulated genes of MAC.GO enrichment analysis revealed that functions of differential genes were primarily concentrated in terms of leukocyte chemotaxis and migration,nucleosome assembly,secreted granular membrane,chemokine receptor binding,etc.KEGG enrichment analysis revealed that the pathways of differential genes were primarily involved in neutrophil extracellular trapping net formation,IL-17 signaling pathway,staphylococcus aureus infection and other pathways.A total of5699 differential genes were obtained between colonic MAC and normal tissues,including 3941 up-regulated genes and 1758 down-regulated genes of MAC.GO enrichment analysis revealed that functions of differential genes were primarily concentrated in terms of extracellular structure,humoral immune response,cell lateral membrane,receptor ligand activity,etc.KEGG enrichment analysis revealed that the pathways of differential genes were primarily involved in neural active ligand-receptor interaction,cytokine-cytokine receptor interaction,IL-17 signaling pathway and other pathways.2.The results of bioinformatics analysis showed that a total of 23 core differential genes between colon MAC and AC,and 24 core differential genes between colon MAC and normal colon tissue were obtained.Among them,PTGS2,IL1 B,TLR2,CXCL8,and SPP1 were the common core genes of the two groups of differential genes.Survival analysis showed that PTGS2 was associated with the prognosis of colonic MAC,and those with high expression of PTGS2 had a longer median survival(p < 0.05).Cox analysis showed that PTGS2 was an independent predictor of overall survival(Overall Survival,OS)in colonic MAC patients(p< 0.05).Other genes were not associated with the prognosis of colon MAC(p>0.05).There was a significant positive correlation between microsatellite instability and PTGS2 expression in colon MAC patients(p < 0.05).Through bioinformatics methods and immunohistochemical staining,we found that the expression of PTGS2 in colon MAC at the m RNA level and protein level was significantly higher than that in colon AC and normal colon tissues,and the difference was statistically significant(p < 0.05).Conclusion:1.Differential genes between colonic MAC and colonic AC and normal colon tissue are mainly enriched in processes such as inflammatory response,vesicle exocytosis,bacterial infection,and IL-17 signaling pathway.These factors may be involved in the occurrence and development of colonic MAC and the mucus pool around cancer cells.2.PTGS2 is a key gene that distinguishes colon MAC from AC and normal tissues,and is an independent predictor of MAC patients.Its high expression predicts higher microsatellite instability and a better prognosis for MAC patients.We speculate that PTGS2 improves the prognosis of patients with colonic MAC by promoting MSI.