The Discovery Of The Prognostic Value Of COPB2 In Glioma And Possible Regulation Function In Tumor Immune Microenvironment: A Bioinformatics Analysis

Background Glioma is the most common malignant tumor in the central nervous system,with high recurrence and lethality rates.According to the categories of the World Health Organization(WHO),brain gliomas are categorized into four grades(I-IV).Glioblastoma multiforme(GBM,grade IV)exhibits a malignant phenotype associated with high proliferative activity,potent invasive ability,and vascular formation with a median survival rate of no more than 15 months post-diagnosis.With the development of biomedical techniques,several biomarkers and molecular classifications of glioma have been established.However,effective and reliable biomarkers that could predict poor prognosis and direct treatment strategies are rare.Thus,the identification of efficient neuropathological biomarkers and therapeutic targets is urgently required.The coatomer protein complex subunit beta 2(COPB2),also known as beta prime-COP or Beta‐Cop,is one of the seven subunits that form coatomer complex I.COPB2 serves as a mediator in the process of protein synthesis which transports proteins from the endoplasmic reticulum(ER)to the Golgi apparatus.Recently,COPB2 has been viewed as a new oncogene and might play a critical role in the development of many cancers,such as breast cancer,prostate cancer and lung adenocarcinoma.Yet,the clinical significance of COPB2 in glioma remains unclear.Thus,this research aimed to reveal the association between COPB2 and glioma and explore the potential prognostic value of COPB2 in glioma patients based on bioinformation and human cancer database.Part Ⅰ Expression level and prognostic value of COPB2 in gliomaPurpose: Bioinformatics was used to analyze the expression level of human COPB2 gene in glioma in different databases,and further study the correlation of clinical features and COPB2,and exam the prognostic value of COPB2 among glioma patients.Method: In the Oncomine human tumor database,the expression level of COPB2 in different tumor types was analyzed using the online tool of bioinformatics,and the expression level of COPB2 in glioma was further analyzed in TCGA and GEO databases.Download the clinical characteristics information of glioma patients in TCGA database and analyze the correlation between COPB2 expression and glioma patients’ age,tumor grade,tumor type,KPS score,tumor load status,survival status,IDH1 mutation and family cancer history through Perl and R language and mann-whitney U test.Kaplan-meier was used to analyze the influence of COPB2 expression level on the total survival time of gliomas patients.Univariate and multivariate risk regression analyses were used to identify risk factors.Results: Relative to normal clinical specimens,COPB2 indicated significant hyper-expression in bladder,brain and central nervous system(CNS),breast,esophageal,head and neck,lung,lymphoma,sarcoma,and other cancers,but hypo-expressed in leukemia.In addition,COPB2’s high expression in glioma patients was further validated in the TCGA and GEO databases.Box plot showed that increased expression of COPB2 correlated significantly with tumor grade,histological type,age,KPS,tumor status and vital status but IDH1 mutation and family history of cancer.Kaplan-meier survival analysis confirmed that patients with high COPB2 expression had low survival rate and poor prognosis.Univariate analysis using logistic regression showed that patients with age >= 52 years old,dead,anvanced tumor grade,glioblastoma,with tumor,KPS score < 80 points,had higher COPB2 expression.And patients’ gender,status,race,family history of cancer and IDH1 mutations had nothing to do with COPB2 expression level.The univariate cox regression revealed that COPB2-high,age,WHO grade,histological type,KPS and tumor status correlated significantly with a worse OS.The multivariate Cox analysis identified COPB2 remained independently associated with OS,along with tumor status.Conclusion: This is the first time that overexpression of COPB2 in glioma was found to be related to the survival of glioma patients and clinical features.COPB2 overexpression can be used as an independent high risk prognostic factor among glioma patients.Part Ⅱ The relationship between COPB2 and glioma immune microenvironmentPurpose: To recognize signaling pathways involved in glioma between low and high COPB2 expression cohorts and explore the role of COPB2 in the progression of glioma.Methods: Glioma patients in TCGA database were divided into high and low COPB2 expression groups.Gene set enrichment analysis(GSEA)was used to induct KEGG signaling pathway enrichment analysis to find out the mechanism of COPB2 in the progression of glioma.Heat map displayed relationship between the COPB2 expression and seven inflammation gene sets(HCK,LCK,interferon,STAT1,MHC I,MHC II and Ig G).To validate the heatmap analysis,a GSVA was conducted to transform gene expression values into enrichment scores for each metagene set.Correlograms were generated(using the R language program)to measure correlations between COPB2 expression and the enrichment scores of the seven metagenes.Canonical correlation analysis revealed that the transcript levels of COPB2 were positively correlated with the marker genes expression of these 6 immune cell types in the TCGA datasets.Results: Gene set enrichment analysis(GSEA)showed that several signaling pathways-especially inflammation and immunity related pathways-were enriched in the COPB2 high expression phenotype,including: B cell receptor,T cell receptor,natural killer cell mediated cytotoxicity,Fc gamma R-mediated phagocytosis,antigen processing and presentation,cytokine cytokine receptor interaction,leukocyte transendothelial migration,and other pathways in cancer.Heatmaps using seven immune related metagenes demonstrated that COPB2 transcript levels were positively correlated with gene sets for HCK,LCK,interferon,STAT1,MHC I and MHC II but negatively with Ig G,a marker basically associated with B cells.These results were verified by correlograms analysis using GSVA.A positive correlation was observed between COPB2 expression and marker genes expression of all 6 immune cell types by canonical correlation analyses.Conclusion: COPB2 is involved in immune-related pathways in the microenvironment of glioma and is closely associated with inflammatory response and immune cell infiltration.