目的　探讨miR-125a-5P在髓母细胞瘤中的表达特点并分析其抑癌作用。方法　采用逆转录PCR方法检测58份髓母细胞瘤组织及2个髓母细胞瘤株D341细胞和Daoy细胞中miR-125a-5p表达水平；瞬时转染D341细胞miR-125a-5P寡核苷酸，免疫荧光方法检测Ki-67核增殖活性，Transwell实验检测细胞迁移力，克隆形成实验检测瘤细胞致瘤潜能；荷瘤鼠模型检测miR-125a-5p转染对体内瘤细胞的抑制效果。结果　miR-125a-5P在儿童髓母细胞瘤组织中的相对表达量明显高于正常儿童脑组织，差异有统计学意义（t=17.55，P<0.01）；miR-125a-5P在神经干细胞、髓母细胞瘤株D341细胞、Daoy细胞、神经胶质细胞和神经元细胞的相对表达量差异有统计学意义（F=9.44，P=0.002）；miR-125a-5P的表达量在神经胶质细胞和神经元细胞中较高，分别高于神经干细胞、髓母细胞瘤株D341细胞和Daoy细胞中的相对表达量，差异有统计学意义（P均<0.05）。与对照组和无义组比较，miR-125a-5p组瘤细胞增殖速度减慢，瘤细胞迁移力降低，肿瘤克隆能力减弱，荷瘤鼠肿瘤体积小，差异均有统计学意义（P<0.05）。结论　miR-125a-5P在髓母细胞瘤中表达降低或缺失，可能是潜在的抑癌基因之一。

　Objectives　To study the expression characteristics of miR-125a-5P in medulloblastoma, and its role as tumor suppressor. Methods　The miR-125a-5p level was detected by stem loop Real-time RT-PCR in 58 cases of medulloblastoma tissues and 2 medulloblastoma cell lines, D341 and Daoy cells. miR-125a-5P oligonucleotide was transfected to D341 cells, then Ki-67 expression was detected by immunofluorescence assay, cell migration was tested by transwell assay, and tumorigenicity was determined by clone formation assay. The inhibitory effect of miR-125a-5p on medulloblastoma cells in vivo was detected in tumor bearing mice model. Results　The relative expression level of miR-125a-5P in medulloblastoma tissues was significantly higher than that of normal children's brain tissue (t=17.545, P<0.01), while the expression level of miR-125a-5P in 2 medulloblastoma cells were significantly lower than other control cells (F=9.437, P<0.01). The expression level of miR-125a-5P was significantly higher than that of the neural stem cells, D341 and Daoy cells, and the difference was statistically significant (P<0.05). Compared with the control group and the non-sense group, the ability of proliferation, migration and clone of cells in miR-125a-5p group obviously declined (P <0.05), as well as the tumor volume in mice (P<0.05). Conclusions　The expression of miR-125a-5P in medulloblastoma was reduced or absent, and was supposedly a tumor suppressor gene.