ABSTRACT
Objective: To investigate the effect of microRNA-34b (miR-34b) on the proliferation of bladder cancer BIU-87 cells, and to exploreObjective: To investigate the effect of microRNA-34b (miR-34b) on the proliferation of bladder cancer BIU-87 cells, and to explore Methods: The expression levels of miR-34b in bladder cancer BIU-87 cells, SV-HUC-1 cells and renal tubular epithelial HK-2 cells were determined by real-time fluorescent quantitative PCR. After transfection with miR-34b mimic, the proliferation rate and clone formation rate of BIU-87 cells were detected by MTT assay and clone formation assay, respectively. After co-transfection with miR-34b mimic and ubiquitin-specific peptidase 22 (USP22)-wide type (WT) or USP22-mutation type (Mut), the specific binding ability of miR-34b to 3'-untranslated region (3'-UTR) in USP22 gene was examined by luciferase reporter system. The expression levels of USP22 mRNA and protein in BIU-87 cells after transfection with miR-34b mimic were detected by real-time fluorescent quantitative PCR and Western blotting, respectively. Results: The expression level of miR-34b in human bladder cancer BIU-87 cells was lower than those in SV-HUC-1 cells and renal tubular epithelial HK-2 cells (both P < 0.05). The proliferation rate and clone formation rate of BIU-87 cells in miR-34b mimic transfection group were lower than those of blank control cells (BIU-87 cells without any transfection) and negative control cells [BIU-87 cells transfected with miRNA mimic negative control (miRNA mimic NC)] (all P < 0.05). The result of luciferase reporter system indicated that miR-34b targeted 3'-UTR in USP22 gene. The luciferase activity of BIU-87 cells in co-transfection with miR-34b mimic and recombinant vector USP22-WT group was decreased (P < 0.05). The expression level of USP22 protein in BIU-87 cells in miR-34b mimic transfection group were lower than those in the blank control and the negative control groups (all P < 0.05). Conclusion: miR-34b can suppress the proliferation of bladder cancer BIU-87 cells. This effect may be related to the expression of USP22.