Bioinformatics Analysis Of Differentially Expressed Genes In Nasopharyngeal Carcinoma And Studies On The Regulation Mechanism Of Mad1/c-Myc/P53 Axis

Nasopharyngeal carcinoma(NPC)is a malignant tumor originating from nasopharyngeal epithelial cells,with a high degree of malignancy and strong metastasis ability.The symptoms of NPC patients with early stage disease are often lacking or nonspecific,which significantly reduced the accuracy of the diagnosis and prediction of the development of NPC.Clinically NPC is often diagnosed in a late stage and has a relatively poor survival rate after diagnosis.Therefore,to study the molecular mechanism of the pathogenesis and development of nasopharyngeal carcinoma and to find molecular markers for the early diagnosis,individualized treatment and prognosis of nasopharyngeal carcinoma has extremely important clinical significance.In recent years,the high-throughput platforms for analysis of gene expression,such as microarray technologies,have been broadly used to obtain general genetic alteration during tumorigenesis.Many gene expression analysis of nasopharyngeal carcinoma involved microarray technology and identified many differentially expressed genes(DEGs)in pathways,molecular functions or biological process according to the literature.However,comparative analysis of DEGs in independent studies shows that there is little overlap,and there is no reliable biomarker to identify nasopharyngeal carcinoma tissues from normal tissues.Despite this progress,the interactions among DEGs and the pathways in the interaction network remain unclear.Therefore,it is of great practical significance to use bioinformatics analysis to dig and integrate data,acquire key genes and signaling pathways related to NPC,and to explore major biomarkers to promote early diagnosis and treatment of NPC.Bioinformatics analysis is an efficient way to analyze biological data,identify genes or gene sets related to the occurrence and development of diseases,and then verified by experiments.In this study,two gene expression profiles(GSE12452 and GSE13597)containing 56 nasopharyngeal carcinoma samples and 13 normal control samples were used as materials to screen differential expression genes of nasopharyngeal carcinoma tissues and normal tissue samples using GE02R.Combined with online bioinformatics analysis tools such as DAVID,KEGG,STRING and literature search,the molecular functions,biological processes and signal pathways of differentially expressed genes were systematically analyzed.10 hub genes were obtained including TOP2A(topoisomerase ?a),CDK1(cyclin-dependent kinase 1),CCNB1(cyclin B1),PCNA(proliferating cell nuclear antigen),MAD2L1(Mitotic arrest deficient 2 such as 1),BUB1(benzimidazole 1 homologues not germinated),CCNB2(Cyclin B2),AURKA(Aurora kinase A),CCNA2(cyclin A2),CDC6(cell division cycle 6 homolog).And the upregulation of these central genes-related molecular pathways in nasopharyngeal carcinoma may activate the pathogenesis of NPC.Then,through the STRING database search analysis,Madl is in a competitive relationship with c-Myc,and Mad1 may bind to the hTERT promoter and inhibit telomerase expression by interfering with c-Myc binding.P53 and c-Myc are co-expression relations,and p53 is involved in cell cycle regulation as a transactivator and plays a role as a tumor suppressor.hTERT is a telomerase catalytic subunit that is the key rate-limiting enzyme for telomerase activity.Telomerase is highly expressed in most human malignancies,including nasopharyngeal carcinoma.PinX1(Pin2/TRF1 interacting protein X1)gene and its telomerase inhibitory domain TID domain can bind directly to human telomerase,and can specifically inhibit telomerase activity,resulting in shortened telomeres and induction of tumor cell apoptosis.Therefore,based on previous studies of the PinX1 gene-targeting telomerase inhibitory activity on nasopharyngeal stem cell activity and its regulatory mechanism of TRFs,we studied the Madl/c-Myc/p53 axis in the PinX1 gene targeting telomerase.The PinX1 over-expression plasmid,empty vector plasmid and PinXl siRNA were transfected into nasopharyngeal carcinoma CD133+ tumor stem cells obtained from the previous stage,and the expressions of PinX1,hTERT,Madl,c-Myc,and P53 genes were further examined by qPCR and Western blot.The regulation mechanism of Madl/c-Myc/P53 signaling pathway was studied.The results showed that the Madl/c-Myc/p53 axis may play an important role in PinX1 gene targeted inhibition of telomerase in nasopharyngeal cancer stem cells.