Abstract:

Objective To study the effects of microRNA（miR）-4429 on the proliferation,migration and invasion of prostate cancer cells,and to investigate the potential related regulatory mechanism. Methods Real-time fluorescence quantitative polymerase chain reaction（RT-qPCR）was used to determine the relative expression of miR-4429 in prostate cancer cell lines（DU145,22rv1,PC3,LNCaP,VCaP） and human prostate epithelial cells（RWPE-1）. The subjects were classified into miR-4429 mimic group,miR-4429 inhibitor group,mimic negative control（NC） group and inhibitor NC group. The effects of miR-4429 on proliferation,migration and invasion of PC3 cells were determined by CCK-8,colony formation test,Transwell chamber test and matrix gel invasion test. The possible target genes of miR-4429 were predicted by bioinformatics analysis,and the binding of miR-4429 and metadherin（MTDH）was determined by luciferase reporter assay. The effects of miR-4429 on MTDH mRNA and protein levels were determined by RT-qPCR and western blotting. Results The relative expression of miR-4429 in 5 prostate cancer cell lines was lower than that in normal human prostate epithelial cells（RWPE-1）（P<0.05）,especially in PC3 cells（P<0.01）. After transfection with miR-4429 mimic,the relative expression of miR-4429 was higher than that in mimic NC group（P<0.01）,and the numbers of clone formation,migration and invasion cells were lower than those in mimic NC group（P<0.01）. After transfection with miR-4429 inhibitor,the relative expression of miR-4429 was lower than that in inhibitor NC group（P<0.01）,and the numbers of clone formation,migration and invasion cells were higher than that in inhibitor NC group（P<0.01）. The binding sites of miR-4429 and MTDH were confirmed by luciferase reporter assay. Compared with RWPE-1,the relative expressions of MTDH mRNA and protein in PC3 cells were increased（P<0.01）. The relative expressions of MTDH mRNA and protein in miR-4429 mimic group were lower than those in mimic NC group（P<0.01）. The relative expressions of MTDH mRNA and protein in PC3 cells transfected with miR-4429 inhibitor were higher than those in inhibitor NC group（P<0.01）. The proliferation,migration and invasion abilities of PC3 cells were promoted by MTDH overexpression. MTDH overexpression reversed the inhibitory effect of miR-4429 on proliferation,migration and invasion of PC3 cells. Conclusions Inhibit miR-4429 could inhibit the proliferation,migration and invasion of PC3 cells,and its mechanism is the down-regulation of MTDH.

Key words: MicroRNA-4429, Prostate cancer, Proliferation, Migration, Invasion