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目的:探讨miR-203a在膀胱癌(BC)细胞系(RT-112、T24、5637、UM-UC-3细胞)中的表达及对细胞增殖及放射敏感性的影响。方法:将miR-203a mimics、miR-203a inhibitor、CDK6 siRNA、CDK6表达质粒及相应阴性对照(NC)转染入BC细胞中。实时荧光定量PCR检测miR-203a在RT-112、T24、5637、UM-UC-3细胞和人膀胱上皮永生化细胞系(SV-HUC-1)中的表达。CCK8实验研究miR-203a和CDK6对BC细胞系增殖的调控。克隆形成实验研究miR-203a和CDK6对BC细胞系放射敏感性的影响。荧光素酶报告基因实验验证miR-203a的靶基因。蛋白印迹法检测miR-203a对CDK6蛋白表达的影响。采用单因素方差分析进行多组间比较、n t检验进行两组间比较。n 结果:与SV-HUC-1细胞相比，miR-203a在RT-112、T24、5637、UM-UC-3细胞中的表达明显降低(n P<0.05)。与NC相比，过表达miR-203a抑制BC细胞系增殖(n P<0.05)，敲低miR-203a促进BC细胞系增殖(n P<0.05)。与NC相比，过表达miR-203a增加BC细胞系的放射敏感性(n P<0.05)，敲低miR-203a减弱BC细胞系的放射敏感性(n P<0.05)。CDK6是miR-203a的作用靶点。与NC组相比，过表达miR-203a显著降低了CDK6蛋白水平(n P<0.05)，敲低miR-203a显著上调了CDK6蛋白水平(n P<0.05)。在转染miR-203a mimics的T24和UM-UC-3细胞中过表达CDK6后，与miR-203a mimics组相比，细胞增殖能力升高、放射敏感性降低(n P<0.05)；在转染miR-203a inhibitor的RT-112和5637细胞中沉默CDK6后，与miR-203a inhibitor组相比，细胞增殖能力降低、放射敏感性升高(n P<0.05)。n 结论:miR-203a在BC细胞系中低表达，可作为抑癌基因抑制BC细胞系增殖和增强放射敏感性。“,”Objective:To investigate the expression of miR-203a in bladder cancer (BC) cell lines (RT-112, T24, 5637, UM-UC-3) and evaluate the effects on BC cell proliferation and radiosensitivity.Methods:Mir-203a mimics, mir-203a inhibitor, CDK6 siRNA, CDK6 expression plasmid and corresponding negative controls were transfected into BC cells. Quantitative real-time PCR was used to detect the expression of miR-203a in BC cell lines and human bladder epithelial immortalized cell line (SV-HUC-1). CCK8 assay was used to investigate the regulation of miR-203a and cyclin-dependent kinases 6(CDK6) on the proliferation of BC cells. Colony formation assay was performed to assess the effect of miR-203a and CDK6 on the radiosensitivity of BC cells. The target gene of miR-203a was confirmed by luciferase reporter assay. The effect of miR-203a on CDK6 protein expression was detected by Western blot. Multi-group comparison was performed by one-way ANOVA and two-group comparison was conducted by n t-test.n Results:Compared with the SV-HUC-1 cells, the expression levels of miR-203a in RT-112, T24, 5637 and UM-UC-3 cells were significantly down-regulated (all n P<0.05). Compared with NC group, overexpression of miR-203a significantly inhibited the proliferation of BC cells, whereas knockdown of miR-203a significantly promoted the proliferation of BC cells (bothn P<0.05). Compared with NC group, overexpression of miR-203a significantly increased the sensitivity of BC cells to radiotherapy, whereas knockdown of miR-203a significantly weakened the sensitivity of BC cells to radiotherapy (bothn P<0.05). CDK6 was the target of miR-203a. Compared with NC group, overexpression of miR-203a significantly down-regulated the expression level of CDK6 protein, whereas knockdown of miR-203a significantly up-regulated the expression level of CDK6 protein (bothn P<0.05). After overexpression of CDK6 in T24 and UM-UC-3 cells transfected with miR-203a mimics, the cell proliferation ability was significantly increased, whereas the sensitivity to radiotherapy was significantly decreased compared with mir-203a mimics (bothn P<0.05). After CDK6 was silenced in RT-112 and 5637 cells transfected with miR-203a inhibitor, the proliferation ability of cells was significantly decreased, whereas the sensitivity to radiotherapy was remarkably increased compared with miR-203a inhibitor group (bothn P<0.05).n Conclusion:miR-203a can serves as a tumor suppressor gene to inhibit the proliferation of BC cells and enhance the radiosensitivity of BC cells.