The Research On The Effect Of DDX39A On The Malignant Biological Behavior Of Glioma Cells And Its Mechanism

ObjectiveGlioma is one of the common tumors in the central nervous system,accounting for4/5 of brain malignant tumors,the 5-year mortality rate ranks third among systemic tumors,it is easy to relapse and has a poor prognosis.Therefore,finding new biomarkers related to the progression and prognosis of glioma can provide a theoretical basis for the early diagnosis and treatment of glioma.The DEAD-box RNA helicase39A(DDX39A)belongs to the DEAD-box helicase(DDX)family,which has the function of enhancing transcription and is widely involved in RNA metabolism,cell cycle regulation,stem cell signal transduction and other processes.Studies have shown that the expression level of DDX39 A is related to the malignant biological behavior of tumors,which can promote the proliferation,invasion and metastasis of tumor cells and is a risk factor for poor prognosis of tumor patients.However,the expression,function and mechanism of DDX39 A in glioma are not clear.This study intends to detect and analyze the expression of DDX39 A in glioma,and observe its effect on the malignant biological behavior of glioma cells and related signaling pathway proteins by changing the expression level of DDX39 A.The purpose of this study is to explore the biological function and mechanism of DDX39 A in glioma,and to provide new ideas for the diagnosis and treatment of glioma.Methods1.Bioinformatics analysis: the expression of DDX39 A in different tumors was retrieved by Gene Expression Profiling Interactive Analysis(GEPIA);The expression of DDX39 A in normal brain tissue and glioma tissues was retrieved by Human Protein Atlas(HPA);The effect of DDX39 A on the overall survival(OS)of patients with different grades of glioma,the correlation between DDX39 A and cell cycle related factors,EMT related markers,WNT/β-catenin signaling pathway key factors were retrieved by Chinese Glioma Genome Atlas(CGGA).2.The m RNA expression of DDX39 A in human normal brain tissue and glioma tissues was detected by real-time polymerase chain reaction(RT-PCR).3.Small interfering RNA(si RNA)and overexpression plasmid were used in glioma cell lines U87 and U251,knockdown and overexpression of DDX39 A,the transfection effect was verified by Western Blot.CCK-8 assay,cell scratch assay,Transwell migration assay and Transwell invasion assay were used to detect the proliferation,migration and invasion of glioma cells.4.The expression of cell cycle-related proteins,EMT-related proteins and key proteins of WNT/β-catenin signaling pathway were detected by Western Blot after knockdown and overexpression of DDX39 A.Results1.The results of bioinformatics analysis showed that: DDX39 A is highly expressed in a variety of tumors,the expression level in glioma tissues was higher significantly than that in normal brain tissues(P<0.05);DDX39A was positively expressed in both low-grade and high-grade glioma tissues;The overall survival of glioma patients with high DDX39 A expression was shorter significantly than that of patients with low DDX39 A expression(P<0.05);In glioma tissues,DDX39 A was positively correlated with the expression of cyclin D1 and cyclin E1(P<0.05),it was negatively correlated with the expression of EMT marker CDH1(E-cadherin)(P<0.05),it was positively correlated with the expression of CDH2(N-cadherin),SNAI1,SNAI2,BRIC5 and TWIST1(P<0.05);It was positively correlated with the expression of CTNNB1,c-Myc and their downstream target genes MMP2 and MMP9(P<0.05).2.RT-PCR results showed that: compared with normal brain tissue,the m RNA expression level of DDX39 A was increased significantly in glioma tissues;And the m RNA expression level of DDX39 A in high-grade glioma(HGG)was higher significantly than that in low-grade glioma(LGG)(P<0.01).3.Transfection of si RNA and overexpression plasmids in glioma cells U87 and U251 can efficiently target knockdown and overexpression of DDX39 A.Compared with the si-NC control group,cell proliferation ability decreased significantly(P<0.05),cell migration ability decreased significantly(P<0.05),cell invasion ability decreased significantly in the si-DDX39 A knockdown group(P<0.05);Compared with the pc DNA3.1(+)-NC control group,cell proliferation ability increased significantly(P<0.05),cell migration ability increased significantly(P<0.05),and cell invasion ability increased significantly in the pc DNA3.1(+)-DDX39 A overexpression group(P<0.05).4.After knockdown of DDX39 A in glioma cells U87 and U251,the results of Western Blot showed: compared with the si-NC control group,the protein expression levels of cyclin D1 and cyclin E1 were decreased significantly(P<0.05);The expression level of EMT-related protein N-cadherin protein was decreased significantly(P<0.05),and the expression level of E-cadherin protein was increased significantly(P<0.05);The expression levels of CTNNB1 and c-Myc protein in the key factors of WNT/β-catenin signaling pathway were decreased significantly in the si-DDX39 A knockdown group(P<0.05).After overexpression of DDX39 A in glioma cells U87 and U251,the pc DNA3.1(+)-DDX39 A overexpression group was compared with the pc DNA3.1(+)-NC control group: the protein expression levels of cyclin D1 and cyclin E1 were increased significantly(P<0.05);The expression level of EMT-related protein N-cadherin protein was increased significantly(P<0.05),and the expression level of E-cadherin protein was increased significantly(P<0.05);The expression levels of CTNNB1 and c-Myc protein in the key factors of WNT/β-catenin signaling pathway were increased significantly(P<0.05).Conclusions1.DDX39 A is highly expressed in glioma tissue,which is related to poor prognosis in patients with glioma.2.DDX39 A can promote the malignant biological behavior of glioma cell proliferation,migration and invasion.3.DDX39 A may promote the proliferation,migration and invasion of glioma cells by cell cycle processes,EMT processes and WNT/β-catenin signaling pathways.