ABSTRACT
Objective To investigate the influences of circular RNA(circRNA)DCUN1D4 on the proliferation,apoptosis and immune escape of lung cancer cells by regulating the microRNA(miR)-18a-5p/fructose-1,6-bisphosphatase 1(FBP1)axis.Methods The human lung cancer cell lines H1975,H1650,A549 and SPCA-1 and human normal lung epidermal cells HPL-1 were selected,qRT-PCR was used to detect the expression levels of circDCUN1D4,miR-18a-5p and FBP1 mRNA in various cells.A549 cells in logarithmic growth phase were selected and divided into the blank group,circDCUN1D4 overexpression plasmid(circDCUN1D4)group,overexpression plasmid negative control(NC)group,circDCUN1D4+miR-18a-5p mimics negative control(circDCUN1D4+mimics NC)group,and circDCUN1D4+miR-18a-5p mimics group.The cell viability of each group was detected by CCK-8 method,the cell apoptosis was detected by flow cytometry,the expression levels of circDCUN1D4,miR-18a-5p and FBP1 mRNA of cells in each group were detected by qRT-PCR,the expression levels of FBP1,caspase-3,Ki67,proliferating cell nuclear antigen(PCNA)and programmed death ligand-1(PD-L1)were detected by Western blot,the targeting relationships of miR-18a-5p with circDCUN1D4 and FBP1 were verified by dual luciferase assay.Results Compared with HPL-1 cells,the mRNA expressions of circDCUN1D4 and FBP1 were significantly decreased(P<0.05),and the expression of miR-18a-5p was significantly increased(P<0.05).miR-18a-5p had targeting relationships with circDCUN1D4 and FBP1,respectively.Compared with the blank group and NC group,the OD values at 24 hours and 48 hours,and the expressions of Ki67,PCNA,miR-18a-5p and PD-L1 of cells in the circDCUN1D4 group were significantly decreased(P<0.05),and the apoptosis rate,and the expressions of circDCUN1D4,FBP1 and caspase-3 were significantly increased(P<0.05).Overexpression of miR-18a-5p reversed the inhibitory effect of circDCUN1D4 on the malignant behavior of lung cancer cells(P<0.05).Conclusion Overexpression of circDCUN1D4 can promote lung cancer cell apoptosis,inhibit lung cancer cell proliferation and immune escape,and its mechanism may be related to the regulation of miR-18a-5p/FBP1 axis.