中文摘要：

研究表明，Hsa-miR-125b在人胃癌耐氟尿嘧啶细胞株BGC823/Fu中表达下降。为进一步探讨hsa-miR-125b在获得性耐药中所起的作用，文章应用miRbase、靶基因预测软件、GeneOntology数据库及KEGG数据库对hsa-miR-125b的序列特征、进化保守性、靶基因及功能以及靶基因所参与的信号通路等进行了深入的生物信息学分析。结果显示：has-miR-125b在多个物种之间具有高度序列保守性；通过软件预测获得hsa-miR-125b靶基因79个，其分子功能包括转录调节、蛋白质结合和肽酶类活性等（P〈0．001），其所参与的生物学过程主要有细胞周期、细胞增殖、细胞凋亡的正性或负性调控以及细胞因子刺激反应性、药物反应性、DNA损伤反应性等（P〈0．001），调控包括MAPK、Wnt、p53等多条信号转导通路（P〈0．01）。上述结果表明hsa．miR．125b可能参与调控多个生物学过程和信号转导通路，而其中细胞增殖、细胞凋亡、细胞周期等生物学过程以及MAPK、Wnt、p53等信号通路已被证实与肿瘤耐药的发生有关。因此，hsa-miR-125b可能通过调控上述环节中的靶基因来影响肿瘤细胞对药物的敏感性，从而为hsa．miR．125b在肿瘤耐药中的作用机制提供新的研究线索。

英文摘要：

The expression of hsa-miR-125b is significantly downregulated in the fluorouracil-resistant cell line of human gastric cancer （BGC823/Fu）. In order to investigate the role of hsa-miR-125b in the drug-resistance acquisition process of human gastric cancer, we performed a series of analysis on the sequence characteristics, species conservation, target genes,function annotation and signal transduction pathway enrichment of hsa-miR-125b using a combined bioinformatic approach such as miRbase, TargetScan6.2, PicTar, miRanda, Gene Ontology（GO） and KEGG. The results showed that the sequence of miR-125b is highly conserved in multiple species. A total of 79 target genes related to transcription regulation, protein binding, enzyme activity （P〈0.001） were predicted by bioinformatics software. These genes involved in many biological processes including cell cycle, cell proliferation, cell apoptosis and cell responses to cytokine, drug responses and DNA damage （P〈0.001）. And these target genes mainly belong to MAPK, Wnt and p53 signal transduction pathways （P〈0.01）. The results revealed that hsa-miR-125b may regulate multiple biological processes and signal transduction pathways, and drug-resistant occurrence is associated with cell proliferation, cell apoptosis, cell cycle and signaling pathways including MAPK, Wnt and p53. We suggest that hsa-miR-125b may affect chemosensitivity by regulating target genes involved in the above processes and these target genes might be reliable candidates for exploring the role of hsa-miR-125b in tumor chemoresistance.