| Objective: Prostate cancer is one of the most common malignant tumors of urinary system,which seriously endangers men’s health.Prostate cancer has the characteristics of concealed onset and slow development.There are almost no symptoms in the early stage.When most patients have difficulty urinating due to tumor compression of the urethra,the cancer may have already developed to the middle and late stage,which seriously affects the treatment of the disease and the prognosis of patients.Through the analysis of large sample gene expression data,this study explores the key genes affecting the occurrence and development of prostate cancer,discusses the key role of related genes in the course and development of prostate cancer,and identify diagnostic markers of prostate cancer and molecular targets affecting tumor prognosis.Methods: The RNA-Seq data and corresponding clinical information of prostate cancer were downloaded from TCGA database;The R language "limma" package was used to analyze and process the transcriptome data,and the differentially expressed genes were screened by taking |log2foldchange|≥2 and FDR<0.05 as the screening criteria;Then,GO and KEGG function enrichment analysis of differential genes was carried out;the interaction between proteins encoded by different genes is analyzed by STRING,and the protein-protein interaction network diagram is drawn by Cytoscape.The MCODE plug-in is used to screen the key sub networks and annotate the functions of genes in the sub networks.The key node genes in protein-protein interaction network are obtained by MCC,MNC and degree algorithms in cyto Hubba plug-in;The expression trend of key genes in multiple data sets was verified by GEO-meta;Chi-square test was used to explore the relationship between the expression of key genes and clinical traits of patients,and Kaplan-Meier and ROC curves were drawn to analyze the value of genes in the diagnosis and prognosis of prostate patients;Real time fluorescence RT-qPCR and IHC were used to verify the expression of key genes at mRNA and protein levels in 33 pairs of cancer and adjacent tissues.Results:The transcriptome data of 540 samples(including 489 PCA samples and 51 adjacent samples)and the clinical information of 485 patients were downloaded from TCGA.A total of 517 differential genes were identified,including 136up-regulated genes and 381 down regulated genes.The functional enrichment analysis of GO and KEGG showed that the differential genes were related to ion transport,substance secretion,hormone synthesis and drug metabolism.The genes in the sub module are mainly involved in G protein coupled receptor and glutathione related pathway.Four key genes(GAL,GNG13,ADCY8,and PENK)were screened by Cytohubba,and GAL and PENK had the same expression trend in multiple datasets.Chi-square test combined with clinical information showed that the expression of PENK was correlated with N stage and Gleason score in patients with prostate cancer(P<0.05);the expression of GAL was correlated with TMN stage and Gleason score(P<0.05).The results of diagnosis and prognosis analysis showed that GAL(AUC=0.869)and PENK(AUC=0.861)had good diagnostic value in prostate cancer,and PENK was closely related to the overall survival of patients(P=0.0033).The results of RT-qPCR showed that compared with adjacent tissues the expression of GAL in PCa increased and the expression of PENK decreased(P<0.05).GAL and PENK proteins are mainly located in the cytoplasm.IRS score analysis showed that GAL was highly expressed in prostate cancer tissues,while PENK was highly expressed in adjacent tissues(P<0.05),which means significant difference.Conclusions: This study integrated a large number of samples from TCGA and GEO,which screened and analyzed key genes in PCA,determined their expression patterns,and further verified the analysis results at the mRNA and protein levels.In conclusion,studies have shown that GAL and PENK are effective diagnostic indicators of PCa.PENK is related to the prognosis of prostate cancer and may become a prognostic marker of prostate cancer.This study found the gene GAL highly expressed in prostate cancer for the first time,which provides an experimental basis for the further study of the molecular mechanism of PCa and provides a certain theoretical and experimental basis for the clinical diagnosis and treatment of PCa. |
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